Many theists believe there is an objective morality to be discovered. However, since you can't uncover such a morality in the same way you can lift a stone and find a pill bug, empirical systems are not use for this process. Instead, many rely on various works that they give implicit trust to, except when the advice of such books goes against their innate beliefs. Hence, we see homosexuals barred from military service, but don't see single women non-virgins barred in such a fashion, much less executed for being a single non-virgin.
Some attempt a seemingly more sophisticated approach of creating a morality based upon a few accepted notions and creating a formal system to reflect it. That's when you see people like the Maverick Philosopher examining the details on what their basic positions entail when examined in detail. Below the fold, I'll go into why I think this helps to pinpoint the inherent lack of objectivity in this construction of a moral system.
I'm not really concerned with the particular argument that Dr. Vallicella is making in his post, rather, I want to highlight what happens when he finds his argument is inadequate. In particular, he doesn't like the breadth of the conclusion of the argument, so he proposes a new starting point. That is, in creating this supposedly objective moral position, he changed his starting point to get the conclusion that he felt was the right one.
Now, I have no objections to this activity per se. In fact, this is one of the better advantages of operating strictly within a formal system. If the starting positions lead you to a situation you can't use, changing the starting positions is to be expected. If you are tracking the movements of ships on the surface of the earth, you don't pretend that the surface of the earth matches Euclid's parallel postulate; instead you assume that no lines (aka great circles) are parallel and use a Riemannian geometry. It will have the tools you need to look at ship movements around a globe.
However, the process of choosing these starting positions is strictly based on the conclusions you want to derive. That makes the starting positions arbitrary, and those positions will be carefully chosen so the results conform to the desired outcome. So, far from getting some objective morality that can be applied to all, you get a tailored morality designed to support a specific set of positions. Some of these systems, like natural law, were debated for hundreds of years before they were codified, and even then still generate disagreements around the edges.
When people come up with another method of knowing things that can exhibit certainty, reality, and demonstrability, that method of know may indeed lead to an objective morality. Until that time, there will be no such creature. All the construction within formal systems will not be able alter the shaky foundation upon which they rest.
Tuesday, December 7, 2010
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«Oldest ‹Older 1001 – 1200 of 2208 Newer› Newest»One Brow said: "Which makes no sense. No one sees it taking 100 years. The traveler sees the light going from star to start in 10 years. The non-traveler see the light going from star to star in ten years."
Why does it make no sense? Isn't that exactly how we, on earth, will percieive it, as I said? SR tells us his clocks have slowed down by a factor of ten. Therefore we know that if we see the journey completed in 10 years, it will be 90 more earth years before he does, right?
What you are saying makes no sense in the context of SR (it makes perfect sense otherwise--many learned people have denied that any time dilation was possible).
But look, you are saying it's
1. 10 lightyears for both him and us, and
2. And that both of us will see it make it journey in 10 earth years (unless you misread my repeateded statements and are saying it will make the journey in 10 of "his" years, which is 100 of our years).
But SR says there will be time dilation (no length contraction in this case). SR also says that he is aging at a much slower rate (same thing), but he can't be doing that if 10 years for him is the same 10 years for us.
aintnuthin said...
Would he have any reason to believe that he was now going "closer to the speed of light" than he was when he left earth, ya figure?
Is he comparing himself to the earth, or to a local light beam?
What would prevent him from reasonably beleiving that? I mean even if his ship had no speedometers, no acceleration detectors, or any other sophisticated instruments.
The better question is, "What would cause him to believe he was closer to the speed of light"? The only answer is 'comparing his current inertial state to his previous inertial state'.
Well, at least that gives me some physical idea of the effects you are talking about. Let me ask this: Is this "flattened appearance" just an illusory appearance,
No. It's real, and has real effects, but it is not local to the yardstick. It's a feature of the difference between the inertial states.
or do physical objects actually get foreshorteden in the direction of motion as the image clearly suggests?
They foreshorten, but not locally, rather as a difference in inertial states.
So "seeing more of my clock" makes you think time runs slower for me, how?
Time doesn't "run slower" for you in any local way. You just run through time differently, due to the difference in intertial states.
Do my clocks actually slow down, as Hafele-Keating et al, claim?
The clocks run through less time, thus appear to have been slowed.
One Brow said: "Except, light is moving at 186,000mph for him."
SR does not say that (although logical positivist advocates of SR certainly do). It says he MEASURES light to be going 186,000 relative to him. What one "measures" is not necessarily accurate and can, in fact, be presumed to be inaccurate if his clock speed has just been decimated as a matter of "reality" (per SR).
What is subjective is to say: If that's what he measured, that's what it is. That's elevates his erroneous miscalculations (i.e., that he is motionless) and his inaccurate conclusions based on misperceptions to the status of fact. Again, just the kinda thing Al (later) railed against in Mach and logical positivists.
One Brow said: "Is he comparing himself to the earth, or to a local light beam?"
Whatever he wants to compare himself to. Probably earth, but maybe "absolute space," (AKA the ether, AKA spacetime) it wouldn't make any difference with respect to the issue of whether he was now travelling closer to the speed of light than when he left earth.
aintnuthin said...
Why does it make no sense? Isn't that exactly how we, on earth, will percieive it, as I said? SR tells us his clocks have slowed down by a factor of ten. Therefore we know that if we see the journey completed in 10 years, it will be 90 more earth years before he does, right?
Yes, I think. He will have moved 90+ lightyears further away when the second star received it's light, so we would have to add that to our calculations of when he will see that event. However, that doesn't seem to be what youare saying.
But look, you are saying it's
1. 10 lightyears for both him and us, and
2. And that both of us will see it make it journey in 10 earth years (unless you misread my repeateded statements and are saying it will make the journey in 10 of "his" years, which is 100 of our years).
But SR says there will be time dilation (no length contraction in this case). SR also says that he is aging at a much slower rate (same thing), but he can't be doing that if 10 years for him is the same 10 years for us.
I think there is a confusion here between what he observes (that is, how he calculates the light to travel from start to star using his inertial frame as a rest frame) and what he sees. In nis inertial frame, the light takes ten years to travel from star to star. Because the stars are moving away from him so quickly in that frame, he sees the events differently.
One Brow said: "The better question is, "What would cause him to believe he was closer to the speed of light"? The only answer is 'comparing his current inertial state to his previous inertial state'."
Sure, that's one good reason. Another might be the contents of the message he got from earth.
Yet another might be his knowledge of SR and it's predictions. Armed with that, he really wouldn't need anybody on earth to tell him how fast they perceived him to be going. He would know that.
And, being a smart cookie, he would NOT reciprocally impute a speed of .99 to earth. He knows better. He's know he, not the earth, is the moving party under these circumstances.
One Brow said: Yeah, that's not what I'm saying, and I didn't also say this to "equalize" the views of him and earth:
"These two stars happen to be moving away from us, and toward him at a rate which keeps them equidistant from both us and the spacehip at all times. So we both see those stars as moving away from us, but the distance remains the same (not that that is important)."
One Brow said: "I think there is a confusion here between what he observes (that is, how he calculates the light to travel from start to star using his inertial frame as a rest frame) and what he sees. "
As I keep saying, I am not concerned with his perspective in this analysis, just ours, and how we might percieive him and his condition from our perspective. As as long as he keeps moving at a rate of .99c relative to us, his clocks will be slowed down by a factor of 10, that's the main thing. Additional delays in travel time can be offset by proper calculational adjustments (by us, and him, as it pertains to the 2 stars).
One Brow said: "They foreshorten, but not locally, rather as a difference in inertial states."
By "difference in inertial states" are you really just saying "difference in relative speed?" I take the difference to be between him and the object he's observing. What does "not locally" mean? Does that mean "globally," or what?
One Brow asked: "How can one object have a state of motion?
How can it not have a state of motion? Is your question about what "can" happen, or are you really just indirectly referring to your conviction that if it did have motion, you, personally, would not know how to ascertain that motion?
One Brow said: Well, Al finally had to conclude (to his utter dismay) that if there was only one globe in the entire universe, and it was spinning, you would know that by it's equatorial bulge (caused by so-called "inerial forces." By the same measure, you would know it if was not rotating.
Last post was in response to this comment of yours:
"You keep talking about things having inertial motion as if it was a property of that one object. As far as I can tell, it isn't."
One Brow said: A contradiction is a statement of the form A & ~A. So, I assume you want to start with a statement such as "The viewpoints of Alice on the ground and Bob on the train are equally valid." [part of this quote didn't copy]
No I prefer to start with a different statement (see below) that you, our phsycist friend, and countless others have made when referring to two relatively-moving objects carrying occupants each of whom assumes he is at rest:
STATEMENT ONE: Based on the following premises, the conclusion stated necessarily follows:
1. Motion exists, whether you want to call it genuine, true, absolute, real, actual, or whatever, I don't care. The main point is a denial of the Parmenidean claim that all motion is an illusion and that motion does not, and can not, exist "in reality."
2. If two observers are moving with respect to each other, it necessarily follows that at least one of them is "really" moving.
3. If each of those two observers assume, claim, or otherwise assert that they are "at rest," then
4. AT LEAST ONE OF THEM MUST BE WRONG.
STATEMENT TWO, made to contradict myself.
No, neither one of them (let alone only one) is wrong because BOTH ARE CORRECT in assuming that they are motionless.
This is the basic fallacy advocated by the alien relationalist "interpreters" of SR. It also ignores the content of SR, but I'll save that for another post (already said it about 50 times, actually).
The contradiction (to common sense and elementary logic) stands on it's own, unless you want to question premise 1. But the relationists never do this. Instead, they ratify SR, in all it's aspects (SR is a theory of "real" motion, not illusory motion), and pretend they understand it better than anyone else. They assure you that, according to SR, all motion is strictly "relative" (by which they mean strictly relational).
They simply refuse to seriously address or acknowledge (as Al finally had to) the implications raised by SR's resolution ofthe twin paradowx (stemming from the LR transforms). All while pontificating for hours about doppler effects, frames of reference, ad nauseum, in the context of the "problem" set up by the twin paradox. This problem, all by itself, presupposes an absolute standard of motion, in light of its resolution. They just continue to deny that there is any way to know or tell which of two relatively-moving observers is "really" moving. Therefore, they claim, each observer is "completely correct" if he assumes he is motionless. By the time they are through, they completely contradict themselves. with their mispreresentations and misinterpretations of SR.
If two objects are moving, relatively to each other, then almost invariably (with the rare exception of two objects whose prior history of acceleration result in them having the exact same speed), then, logically, one is moving faster than the other.
1. That is true EVEN IF we, personally, in our state of ignorance, haven't the slightest clue of which one is moving faster.
2. That is true EVEN we know no (and even if there is no) point which can be shown to be at "absolute rest." We do not have to know their "absolute velocity" to know that one must most certainly be faster than the other.
3. In terms of SR theory, we could presumably ascertain which one is actually moving faster by determining which one is aging less, etc.
Of course all of the above presupposes my basic premise that objects move, collide, explode, etc. in nature even if no living human being knows just how, when, or why those things occur (or occurred in the past). The question of which one is "faster" does NOT reduce to "how can you tell" as a matter of theoretical physics. Physics, as a discipline, presuppose the existence of an independent "real" objective reality consisting of matter in motion. It further presupposes that material objects may have qualities, attributes, and histories which we do not fully know or fully understand. Nonetheless, physics plows on, and only the solipisists claim that is it merely a metaphysical, fiction-based enterprise.
One Brow said: "Then it is wrong, experiementally. If a light source is moving at v with respect to a laboratory, the light from the light source does not proceed at v + c in the laboratory, it only proceeds at c."
You still don't seem to get what I'm saying. I already said:
"Within LR, the relativity principle is upheld via the usual invariant gallilean transformations. That said,it also predicts, and deals with, the consequences of the LR transformations because they exist and must be considered and accounted for in any theory of motion."
Let me elaborate. As I understand it (I'm certainly no expert, but....)
1. In LET, the effects caused the lorentz transforms exist, and they explain why observers measure the speed of light to be constants in all inertial frames, just as in SR. It would be more historically accurate to say that SR mimics LR in this respect, but that's really just a sidenote.
2. The Gallilean transforms cannot work if t (time) is not kept constant from frame to frame.
3. Al couldn't consistently apply the Gallilean transformation to Maxwell's equations, and the problem vexed him for years. He was apparently unaware of Hertz's refinement of Maxwell's equations which rendered them gallilean invariant within the context of Newtonian mechanics. What he would have made of Hertz's equations, had he been aware of them, I cannot say.
4. Al ending up throwing out time as a constannt from frame to frame. Dumping time as a constant left him free to devise a new postulate which would establish Gallileo's relativity principle and apply it to electro-magnetic phenomena. This resulted in the "invariant speed of light" postulate.
5. LET retains "abolute" time, i.e., a single time which is derived from a preferred frame and then extended to all inertial frames.
6. Keeping time constant allowed a reversion to Gallilean relativity, but it precluded the existence of an invariant speed of light in all inertial frames.
7. To convert all frames to a univeral time, LET must first "correct" the time and length distortions caused by increased motion. After that, each frame does not have it's own "unique" time any more than did Newton's frames.
continued in next post:
Ether is not essential to LET, but a preferred frame is. These days it's gravition that supples the preferred frame. Einstein, I'm told always insisted that spacetime in GR was gravity. Not as something that contained, or interacted with, gravity but the exact identical thing. Spacetime=gravity in GR, per Al, so there may be more similarities than is commonly assumed. Recall that also later said that GR would be "unthinkable" without the ether, and that the absolute space of Newton, the ether, and spacetime were basically all the same thing: A conceptual background without which physics could say nothing meaningful.
Basically, LR just kept time constant, which I personally believe is more appropriate since "time" is really just a very abstract concept with no corporeal existence. These days, many "new-age" theorists want to impute a tangible, physical existence to time and reify it into something you can move rhough. SR did a lot to start a trend toward this kind of abstract, metaphysical treatment of physics.
Speed is nothing more than a dividend of time and length, and they are therefore primary to it, conceptually. Furthermore, speed is a rate, and that creates it's own complications. As they say, "you can't square a speed."
Trying to make a particular speed constant, come hell or highwater, while refusing to correct what are known to be distorted standards of time and length, leads to a lot of confusion, "paradoxes" ambiguities, vague concepts, etc. and I think SR is inferior to LR on that score. Having a different time for virtually an infinite number of "frames" does not help either.
Since time and length combine to determine speed, the 3 concepts are intimately related, and can, mathematically speaking, be manipulated in many diffent ways to get the same results. That's why SR works just as well as LR in a mathematical/predictive sense. If you like SR slogans, then you might be inclined to say that SR and LR are "equally valid."
One further response to this question:
One Brow said: "You keep talking about things having inertial motion as if it was a property of that one object. As far as I can tell, it isn't."
One way of looking at "inertial motion" is that a particle partaking of it is a "free particle" (free, because not be acted on or influenced by other forces, including accelerating forces). Why couldn't any given particle be a free particle (again, whether you have any way of assuring yourself that that is it's true status, or not)?
As long as you keep asking the question, I'll keep giving my best response. I don't think inertial motion, per se, depends on my knowledge of it. Yet I think that's your underlying assumption..i.e., that unless you have some means of confidently labelling it as a "free particle" then it "can't" be one). I think, and will probably always think, that this is a mistaken view which puts the focus and emphasis on the wrong thing (for physics). What you know is nice to know, but the motions, interactions, etc. of particles in the universe will be what they are, whether you know it or not.
aintnuthin said...
Sure, that's one good reason. Another might be the contents of the message he got from earth.
That's just relying on the earth to make the same comparison.
Yet another might be his knowledge of SR and it's predictions. Armed with that, he really wouldn't need anybody on earth to tell him how fast they perceived him to be going. He would know that.
However, accordin to SR, it could have been the earth that was traveling at .99c all along, and him that just slowed to to 0. So, he would be further from the spped of light.
And, being a smart cookie, he would NOT reciprocally impute a speed of .99 to earth. He knows better. He's know he, not the earth, is the moving party under these circumstances.
He knows earth didn't accelerate from 0 to .99c. How does the smart cookie know earth wasn't moving at .99c all the time?
As I keep saying, I am not concerned with his perspective in this analysis, just ours, and how we might percieive him and his condition from our perspective.
Then, you're going to stop talking about what he sees? OK.
By "difference in inertial states" are you really just saying "difference in relative speed?"
We could use that.
I take the difference to be between him and the object he's observing. What does "not locally" mean? Does that mean "globally," or what?
It means the change is dependent on the difference in inertial states, and does not belong to the oberver nor the yardstick.
One Brow asked: "How can one object have a state of motion?
How can it not have a state of motion?
Either way. How can one object have ornot have a state of (inertial) motion? What does that mean?
Is your question about what "can" happen, or are you really just indirectly referring to your conviction that if it did have motion, you, personally, would not know how to ascertain that motion?
I'm saying that inertial motion is a relative state that requires at least two objects (or an object and an inertial frame), onr of which is not moving.
"You keep talking about things having inertial motion as if it was a property of that one object. As far as I can tell, it isn't."
Well, Al finally had to conclude (to his utter dismay) that if there was only one globe in the entire universe, and it was spinning, you would know that by it's equatorial bulge (caused by so-called "inerial forces." By the same measure, you would know it if was not rotating.
Rotation is not inertial motion, it is accelerated motion.
No I prefer to start with a different statement (see below) that you, our phsycist friend, and countless others have made when referring to two relatively-moving objects carrying occupants each of whom assumes he is at rest:
Except, those various positions you are quoting from mainstream SR don't even recognize the concept of "assumes he is at rest".
STATEMENT ONE: Based on the following premises, the conclusion stated necessarily follows:
1. Motion exists, whether you want to call it genuine, true, absolute, real, actual, or whatever, I don't care. The main point is a denial of the Parmenidean claim that all motion is an illusion and that motion does not, and can not, exist "in reality."
2. If two observers are moving with respect to each other, it necessarily follows that at least one of them is "really" moving.
3. If each of those two observers assume, claim, or otherwise assert that they are "at rest," then
4. AT LEAST ONE OF THEM MUST BE WRONG.
STATEMENT TWO, made to contradict myself.
No, neither one of them (let alone only one) is wrong because BOTH ARE CORRECT in assuming that they are motionless.
I'm sorry, was there supposed to be a "statement (see below) that you, our phsycist friend, and countless others have made when referring to two relatively-moving objects carrying occupants each of whom assumes he is at rest". They would recognize motion exists in relation to things that are not moving, but the notions of "really moving" and asserting that they are "at rest" are not part of mainstream SR.
Your effort was very sloppy and filled with equivocation. Feel free to try again. Be careful and precise, this time. If it helps, use my starting point.
This is the basic fallacy advocated by the alien relationalist "interpreters" of SR. It also ignores the content of SR, but I'll save that for another post (already said it about 50 times, actually).
That your understanding of this is so sloppy and imprecise says much about the degree to which you understand the content of SR.
Basically, LR just kept time constant, which I personally believe is more appropriate since "time" is really just a very abstract concept with no corporeal existence. These days, many "new-age" theorists want to impute a tangible, physical existence to time and reify it into something you can move rhough. SR did a lot to start a trend toward this kind of abstract, metaphysical treatment of physics.
This is one of the problem areas of LET, for me. If time does not have a coporal existence, but is just an abstract concept, why should it be consistent from frame to frame? How does an abstract concept impose itself to upon real objects? This is like saying I drove from St. Louis to Davenport in 450 miles, so every time you make the trip, even if you go through Chicago, Lincoln, or Minneapolis on the way, it's going to be exactly 450 miles.
Sory, but mainstream-SR doesn't see time as being more (or less) tangible than distance. There is no reification, no corporeal existence, just noting that the very notion you that the existence of different times means come kind of dimensional quality that can be measured. If it couldn't, then there would be no concept of speed to begin with. It time does not pass in some regular, measurable way, then there is no difference between going 60 mph and 1 mph. Either way, you'll travel a mile. If time is not regular and measurable, then there is no way to say you arrive first by going 60 mph. The whole concept doesn't make sense.
You're welcome to LET, but the paradoxes it proposes are far more fundamental and troublesome, to me. I see no reason why time should have so much power over matter that it decides how matter moves through it.
Still, we come across a good test to separate mainstream-SR from LET (as you have come to describe it). Put an obervation unit in fast motion compared to someting at rest, and then compare clocks while the observer is moving. If the moving observer see the clock at rest moving faster, LET is verified. If not, mainstream-SR is verified. Let me know when they do this experiement.
Trying to make a particular speed constant, come hell or highwater, while refusing to correct what are known to be distorted standards of time and length, leads to a lot of confusion, "paradoxes" ambiguities, vague concepts, etc. and I think SR is inferior to LR on that score. Having a different time for virtually an infinite number of "frames" does not help either.
The paradoxes of SR are those of using vastly different inertial frames, and seem like aradoxes because they are outside of our experiences. The paradoxes of LET submit the universe to domination by an abstract concept.
One way of looking at "inertial motion" is that a particle partaking of it is a "free particle" (free, because not be acted on or influenced by other forces, including accelerating forces). Why couldn't any given particle be a free particle (again, whether you have any way of assuring yourself that that is it's true status, or not)?
Since the circumstances of being free are related tot he environment, and not the particle itself, any particle could be free.
As long as you keep asking the question, I'll keep giving my best response. I don't think inertial motion, per se, depends on my knowledge of it.
I agree.
Yet I think that's your underlying assumption..i.e.,
Yet, you are wrong, again, and seem to prefer persisting in your error rather than correcting it.
One Brow said: "Then you have discovered an experiemntal way to verify LET over SR (as understood by the vast mahjority of physicists). Mention this to a few LET-friendly physicists, have one of them get grant money, and test it."
You misinterpreted my response.
You had said: "One Brow said: "There is no "requirement" for reciprocity. It exists, required or otherwise. What we do or not not require does not affect reality."
My response was: "The demand for reciprocal transformations comes from relationalists, and "exists" only to that extent."
You basically presented the reciprocity as a empirical fact which existed totally independently of the conceptual framework established by SR. It isn't, to the extent we have been able to demonstrate it, at least. It is a conceptual interpretation, as is LR's non-reciprocal interpretation.
But, on the conceptual level, SR's "requirement" of reciprocity leads to difficulties (such as the one I'm going to address where, suddenly, Jack must use binoculars). As I have already argued in other posts, the insistence that reciprocity is "real" basically leads to a Parmenidean notion of reality. Why? Because, at bottom, it requires each and evey observer to assume that he is at rest. But if every single observer is "at rest" then, as Parmenides claimed, all motion is simply an illusion.
One might say that it (the reciprocity requirement) only says that you must consider any object moving "relative to you" to be the one moving. It all leads to the same place, in the end, and, taken literally, it requires me to assume I'm "at rest" if I'm riding my motorcycle through the country. If I don't, then I'm not adhering to the "reciprocity of frames" requirement.
The supposed "necessity" of frame reciprocity is the ultimate origin of the assertion, in the typical "person on the embankment vs person on the train" presentation, that the person on the train "assumes he is at rest and "is correct." If he is not correct, then the earth has been implicitly established as a "preferred frame." If that is done, then the observer on the train will no longer see the relativity principles as being true. The speed of light will not be 186,000 mps for him if he uses the earth as the proper reference frame.
So SR "prohibits" that perspective. But any fool and his brother would adopt it anyway. Nobody "really" assumes that the entire earth is moving while they are perfectly motionless on the train.
One Brow said: "This is like saying I drove from St. Louis to Davenport in 450 miles, so every time you make the trip, even if you go through Chicago, Lincoln, or Minneapolis on the way, it's going to be exactly 450 miles.
Sory, but mainstream-SR doesn't see time as being more (or less) tangible than distance. There is no reification, no corporeal existence, just noting that the very notion you that the existence of different times means come kind of dimensional quality that can be measured. If it couldn't, then there would be no concept of speed to begin with. It time does not pass in some regular, measurable way, then there is no difference between going 60 mph and 1 mph. Either way, you'll travel a mile. If time is not regular and measurable, then there is no way to say you arrive first by going 60 mph. The whole concept doesn't make sense."
Heh, and you want to accuse me of "sloppy thinking?"
One Brow said: "Yes. I went back and read it again. There is no hint of Jack not being able to see his own clock, nor of getting a speed of light ther than the usual. That was you."
Well, you just demonstrated how easily students can be fooled by clever "sleight of hand." Read it again. How does Jack arrive at his conclusion about the speed of light as he sees it on the train? Did he ever refer to his clock in order to arrive at the "distance travelled/time elapsed" components which he used to arrive at the "proper" speed of light?
I said: "Nobody "really" assumes that the entire earth is moving while they are perfectly motionless on the train."
For more accurate expression "Nobody assumes that the entire earth is "really" moving while they are perfectly motionless on the train."
Yet that is what SR insists that you MUST do--at least if Al's relativity principle is to be honored.
And I could have added: And anyone who did probably needs to check in Bellevue.
One Brow said: "They would recognize motion exists in relation to things that are not moving, but the notions of "really moving" and asserting that they are "at rest" are not part of mainstream SR."
Please speak for yourself, rather than "mainstream SR."
No notion of "at rest," eh? How about "at rest with respect to everything else in the universe?" As in "frame of reference."? Isn't that what each and every "frame of reference is presumed to be--at rest? Frame of reference = at rest with respect to every other thing in the universe in SR, right?
Isn't that what "Bill's frame of reference is?" And "Mary's frame of reference?" And every other of an infinite number of frames of reference? In SR, your "frame of reference," whatever it is, MUST be your preferred frame.
No notion of "really moving," eh? When you explain to every ignorant fool just how the twin paradox isn't any kind of paradox at all because (w, y, & z), isn't the travelling twin presumed to be "really moving?" Or are his "travels" merely illusionary?
One Brow said: "They would recognize motion exists in relation to things that are not moving..." What things are "not moving?"
aintnuthin said...
You basically presented the reciprocity as a empirical fact which existed totally independently of the conceptual framework established by SR. It isn't, to the extent we have been able to demonstrate it, at least. It is a conceptual interpretation, as is LR's non-reciprocal interpretation.
However, each interpretation is empirically verifiable. If you have two objects at rest, and accelerate one of them, either each will see the other's clock going slower (reciprocity) or the moving one will see the stationary clock going faster (non-reciprocity) after adjusting for the effects of gravity. It should be visible right now, from GPS satellites.
That is, unless you hyave an explanation for the appearance of reciprocity that fits into your notion that one clock has really slowed down. You never offered one.
Because, at bottom, it requires each and evey observer to assume that he is at rest.
Incorrect. You are confusing the notion of a valid point of view with an assumption of some ontological fact.
If he is not correct, then the earth has been implicitly established as a "preferred frame." If that is done, then the observer on the train will no longer see the relativity principles as being true. The speed of light will not be 186,000 mps for him if he uses the earth as the proper reference frame.
If the observer on the train does the proper conversions to the earth-at-rest reference frame, the speed of light will still be 299,792,458 meters per second in that reference frame. You've been getting different numbers by trying to mix reference frames together. However, the EEP does not claim light is constant under any conceivable reference frame, just under frames based on inertial states. When you mix two different inertial frames together, it is no longer an inertial frame.
Heh, and you want to accuse me of "sloppy thinking?"
I'm not trying to persuade you, so I'm not worried about the rigor there. To get really rigorous, I'd have to go back into mathematics that I haven't used in 25 years, and have mostly forgotten.
Well, you just demonstrated how easily students can be fooled by clever "sleight of hand." Read it again. How does Jack arrive at his conclusion about the speed of light as he sees it on the train?
From the notion that the speed is light is constant.
Did he ever refer to his clock in order to arrive at the "distance travelled/time elapsed" components which he used to arrive at the "proper" speed of light?
No. Now, how does that prevent Jack from observing his own clock?
Please speak for yourself, rather than "mainstream SR."
Since we are in accord here, there is no difference.
No notion of "at rest," eh? How about "at rest with respect to everything else in the universe?" As in "frame of reference."? Isn't that what each and every "frame of reference is presumed to be--at rest? Frame of reference = at rest with respect to every other thing in the universe in SR, right?
Again, the issue is not that you misunderstood what a frame of rest is, but that you have confused a valid claim with a statement of ontological fact.
What things are "not moving?"
That can't be deternmined within SR. Fortunately, the answers to any physical problems are the same regardless of which assumption you make about things that are or are not moving.
One Brow said: "However, each interpretation is empirically verifiable. If you have two objects at rest, and accelerate one of them, either each will see the other's clock going slower (reciprocity) or the moving one will see the stationary clock going faster (non-reciprocity) after adjusting for the effects of gravity. It should be visible right now, from GPS satellites.
That is, unless you hyave an explanation for the appearance of reciprocity that fits into your notion that one clock has really slowed down. You never offered one."
This is just wrong, on many counts. You have been given the explanation dozens of times, you just refuse to, or can't, understand it. Nobody "SEES" the other's clocks moving slower, they "see" a difference, at best. From that difference, the question of which one is moving slower is a matter of deduction based on assumptions. That, and no more.
You've been TOLD, so many times, that each "sees" the other's clock as moving slower by relationalists, and you have unquestionably swallowed it, uncritically and undigested, that you can't imagine it not being 100% true as a matter of empirical fact. Think about the guy on the train, or the guy on the embankment watching him. Think what either of them would "see" if they didn't BOTH "assume" they were at rest and the other guy was moving (a mutually exclusive situtation).
Scientists have never figured out an empirical way to "test" SR vs. LR, yet you have, on the spot. Many you should publish in Physics Letters, eh? Who knows, mayber you'll end up winning a Nobel Prize for you ingenious insight.
One Brow said: "Because, at bottom, it requires each and evey observer to assume that he is at rest.
Incorrect. You are confusing the notion of a valid point of view with an assumption of some ontological fact."
No, I am not. For SR to "hold true," every observer MUST assume he is "at rest" and that everything else is moving relative to him. If they don't, they will not conclude that the speed of light in constant. The whole theory is based upon mutually exclusive assumptions of facts, based on what each observers is told he must believe, even if he doesn't belive it (e.g., that he is motionless with respect to the earth, and the earth is moving past him, when he is on a moving train).
Without SR dictating how an individual must perceive his own state of motion, it all falls apart. Of course, any theory based on each observers subjective belief, or idiosyncratic perspective, is, to begin with, not really a physical theory at all. It is new age woo. Physics doesn't depend on what a particular individuals "believes."
The post before this one was deleted. Maybe my last post will be too, now that I've made this one.
One Brow said: "If the observer on the train does the proper conversions to the earth-at-rest reference frame, the speed of light will still be 299,792,458 meters per second in that reference frame."
Sure he would. That exactly what LR would (and does) do, i.e., make the proper conversions.
One Brow said: "When you mix two different inertial frames together, it is no longer an inertial frame."
What are you talking about? What is "it?" The earth is an inertial frame, and the train is an inertial frame. If I naturally and rightfully assume that I, on the train, am moving with respect to the earth and that it is not moving past me while I remain absolutely motionless, then that changes nothing about "inertial frames." It does, however, mean that I won't see the speed of light to be constant in all inertial frames.
I asked: How does Jack arrive at his conclusion about the speed of light as he sees it on the train? Did he ever refer to his clock in order to arrive at the "distance travelled/time elapsed?
You responded: "From the notion that the speed is light is constant."
Earlier you said: "There is no hint of Jack not...getting a speed of light other than the usual. That was you."
The "usual" method of measuring speed is to (1) measure the distance travelled and (2) divide it by the time elasped (on a clock). It is not to forego this simple empirical means of determining speed and assuming, a priori, that you already know what it is.
This professor makes a big to-do about Jack testing clocks and comparing them. He never does any such thing. Ask yourself what he would have seen if he had simply looked at both light clocks simultaneously, rather than going through elaborate and convoluted algebraic and geometical calculations to "deduce" time and distance.
It doesn't really strike me as odd that you would call this the "usual" method of "demonstrating" your point. You simply reassert your conclusion (the point you are purporting to "demonstrate") and call it done.
Like the time you refused to listen to a word anyone said, and just kept referring them to the computer simulations which incorporated your mistaken (but absolutely unshakable) assumptions, remember? You haven't changed.
One Brow said: However, accordin to SR, it could have been the earth that was traveling at .99c all along... How does the smart cookie know earth wasn't moving at .99c all the time?"
You are partially right about your "according to SR" claim. Actually, according to SR, it's not the the earth "could have" been moving. SR REQUIRES our highly accelerated traveller to believe it has been moving. No "could" about it.
Do you really expect me to have to answer your question about how he knows the earth wasn't moving away from him while he remained absolutely motionless all that time? The answer is too obvious to require restatement.
I asked: "Is your question about what "can" happen, or are you really just indirectly referring to your conviction that if it did have motion, you, personally, would not know how to ascertain that motion?
You responded: "I'm saying that inertial motion is a relative state that requires at least two objects (or an object and an inertial frame), onr of which is not moving."
No it doesn't. That only required for YOU to perceive it. Nothing I know of would prevent a single object, alone in the universe, from moving at a constant rate of speed in the same direction.
Even when I ask a question specifically designed to understand and acknowledge that there is (or at least could be) a difference between your perception and an object's motion, you still can't see the difference.
One Brow said: "It should be visible right now, from GPS satellites."
All clocks in the GPS satellites read the exact same time as does the clock in the ECI frame. You might ask yourself why that is. When Keating, et al, send a clock in motion, the one moving comes back reading less time. Why should it see the earth clock the same? Only one of the two has slowed down, not both. One says, for example, that it's now 5:00 o'clock, and the other might say it's now 5:05. Why should the one saying it's 5:05 think it's reading 5:00 and the other is reading 5:05 (or vice versa)?
This post may be in the spam bin (but I think it failed to post because I was editing it as it was trying to post:
One Brow said: "It means the change is dependent on the difference in inertial states, and does not belong to the oberver nor the yardstick."
Doen't belong to the yardstick, eh? Then this is not the "real physical change" that Hogg (following Al) says it is. A "change in appearance" due to a change in perspective is not a "physical change," sorry. Only you would think that.
Doen't "belong" to the observer either? So the yardstick doesn't change, and neither does the observer's perception of it? Then why would anyone bring up the notion of any "change" at all? Ever ask yourself that?
I said: "A "change in appearance" due to a change in perspective is not a "physical change," sorry."
To illustrate the difference, consider a square table top, five feet by five feet. That's what the top measures.
That said, the table top never "appears" square to us, unless we are standing over it with our head right in the middle of the table. As we move around the room and look at the table top, it takes on the "appearance" of many different shapes and sizes (of the respective sides).
But the table top does not physically change. It always remains 5 feet by 5 feet, if you measure it. All the variation in appearance is caused solely by perceptual changes, not physical changes.
You want to say that the changes are "real" and are "physical changes" because an observer "really" sees them and because "seeing" is a physical process. Fraid it don't work that way.
aintnuthin said...
This is just wrong, on many counts. You have been given the explanation dozens of times, you just refuse to, or can't, understand it. Nobody "SEES" the other's clocks moving slower, they "see" a difference, at best. From that difference, the question of which one is moving slower is a matter of deduction based on assumptions. That, and no more.
You can compare the ticks of clock A to the ticks of clock B to wee which one is faster. If the ticks are for a short enough time, you can do this in a way that makes this comparison fairly straight-forward.
Scientists have never figured out an empirical way to "test" SR vs. LR, yet you have, on the spot. Many you should publish in Physics Letters, eh? Who knows, mayber you'll end up winning a Nobel Prize for you ingenious insight.
Frankly, I'm not sure the position you are putting forth is standard LET to begin with.
No, I am not. For SR to "hold true," every observer MUST assume he is "at rest" and that everything else is moving relative to him.
No. You are confusing the notion of the validity of a claim with an expression of ontological fact.
If they don't, they will not conclude that the speed of light in constant.
The speed of light is considered constant in a constant medium for a single inertial frames. It is not supposed constant when interpreted simultaneously in different inertial frames. Your example of how person A interprets person B interpreting an event mixed inertial frames. There is no reason in standard SR to expect light would hold to a constant speed under those circumstances, just like it is not expected under conditions of acceleration (which is basically a change in intertial frames).
One Brow said: "When you mix two different inertial frames together, it is no longer an inertial frame."
What are you talking about? What is "it?"
Your analysis of how the earth would interpret the the view of the traveler who saw the light betw2een two stars as taking ten years to make the journey.
The "usual" method of measuring speed is to (1) measure the distance travelled and (2) divide it by the time elasped (on a clock).
Light is not usual.
This professor makes a big to-do about Jack testing clocks and comparing them. He never does any such thing. Ask yourself what he would have seen if he had simply looked at both light clocks simultaneously, rather than going through elaborate and convoluted algebraic and geometical calculations to "deduce" time and distance.
Jack sees his light and Jill's light going at the same speed, and Jill's light taking longer to make the transition within the light clock than Jack's light takes. Nothing there contradictory to SR.
Like the time you refused to listen to a word anyone said, and just kept referring them to the computer simulations which incorporated your mistaken (but absolutely unshakable) assumptions, remember? You haven't changed.
I see it a an excellent example that I do acknowledge my mistakes, when I get a good explanation of why they need to change. You have failed to provide a good explanation.
Do you really expect me to have to answer your question about how he knows the earth wasn't moving away from him while he remained absolutely motionless all that time? The answer is too obvious to require restatement.
Re-statement implies statement. There has been no statement, beyond a simple philosophical preference to which I have no objection.
You responded: "I'm saying that inertial motion is a relative state that requires at least two objects (or an object and an inertial frame), onr of which is not moving."
No it doesn't.
You have already acknowledged that it does, by agreeing that motion has to be in relation to something not moving.
Nothing I know of would prevent a single object, alone in the universe, from moving at a constant rate of speed in the same direction.
Not did I claim anything would prevent that.
Even when I ask a question specifically designed to understand and acknowledge that there is (or at least could be) a difference between your perception and an object's motion, you still can't see the difference.
Your so bound up in your absolutism that you can't see the difference between relative, relational, and perceptual. Only the first describes my understanding.
All clocks in the GPS satellites read the exact same time as does the clock in the ECI frame.
As they should, and not relevant to the point that, according to your interpretation, after adjusting for the differences in gravity, they should see the clocks on earth running faster they do, rather than slower.
When Keating, et al, send a clock in motion, the one moving comes back reading less time.
As expected, but again dodging the point rather than responding to it.
One Brow said: "It means the change is dependent on the difference in inertial states, and does not belong to the oberver nor the yardstick."
Doen't belong to the yardstick, eh? Then this is not the "real physical change" that Hogg (following Al) says it is.
Incorrect. You can have physical changes in a system of things that are not changes specific to the individual things. Hogg's exposition in no way contradicts this.
A "change in appearance" due to a change in perspective is not a "physical change," sorry. Only you would think that.
I neither think that nor have claimed that.
Doen't "belong" to the observer either? So the yardstick doesn't change, and neither does the observer's perception of it?
The observer's perception, based upon real changes in the system of things, changes.
But the table top does not physically change. It always remains 5 feet by 5 feet, if you measure it.
If you return to the view where you are directly above it, and measure it, it will always be a 5 foot square. Just as if you return the yardstick to your inertial frame and measure it, it will be be a yard long.
All the variation in appearance is caused solely by perceptual changes, not physical changes.
Lights set at different places will create different shadows, causing different amounts of heat to be absorded by the table versus the background, or absorbtion in different parts of the background, even though the table and the light are not altered. A change in the position of the light to the table is a physical change, even though the light and the table are unaffected. This is true whether there is an observer or not.
You want to say that the changes are "real" and are "physical changes" because an observer "really" sees them and because "seeing" is a physical process.
I say that because there are real, physical effects.
"This is one of the problem areas of LET, for me. If time does not have a coporal existence, but is just an abstract concept, why should it be consistent from frame to frame?"
For you to even ask this question reveals that you don't know what a "concept" is. Perhaps you should go back and re-read Al's explanation of the question of length. You know, the one where Al was castigating the positivists' understanding of the concept of length, and the explanation you said, at the time, that you agreed with?
One Brow said: "The paradoxes of LET submit the universe to domination by an abstract concept."
Heh, well they should call Al, not Lincoln, "the great emancipator," eh? Lincoln only freed a small population of one race in one country from slavery. Al freed the entire universe from domination--all observers, all places, all times. No comparison, really. Never mind that he dictates the way they must see their own state of motion.
I had no idea this was such an emotional issue for you, Eric, although it does tend to explain a lot about the claims you make and the answers you give. If I thought LET was out to dominate the universe, I would git bizzy slappin some buckshot in my sawed-off shotgun every time I heard some LET advocate was floatin around my parts, too.
One Brow said: "You are confusing the notion of the validity of a claim with an expression of ontological fact."
No, I'm not talking about an expression of ontological fact, I'm talking about the logical structure of a purportedly "physical" theory of motion. The theory, qua theory, requires that each observer presume that he is motionless and that all other things are moving with respect to him when evaluating the speed of light as being either constant or not.
The "speed of light" can only be "constant" if every observer makes an assumption about the other observer which opposes and contradicts the assumption that the other observer makes about that same matter. As soon as both I (on the train) and you (on the embankment) actually AGREE on who's moving, then SR is off. No more constancy of the speed of light. The theory requires that two observers disagree on the basic state of facts. Both cannot be right, and "disagreement" (or lack thereof) is not the basis for analyzing physical motion to begin with.
That's what the theory requires. It certainly is not an "ontological fact" that both are simultanously moving and both are simultaneously not moving. That's just what the theory requires you to assume about two observers. That is also why every "explanation" of SR constantly says "but if you look at it from the other guy's frame of reference, then...."
It's like if I said Bin Laden was dead, then I would immediately be told that I now have to perceive all the reports of his death from the perspective that he never really died. I must constantly switch from presuming he's dead to assuming he's not dead. Only to be told that both (he's dead, and he's not dead) are equally valid, equally possible, equally true because the only truth is that there is no truth, and that all is "relative."
The internal contradiction is apparent to anyone who cares to think about it. That is the flaw in the theory.
One Brow said: "Jack sees his light and Jill's light going at the same speed, and Jill's light taking longer to make the transition within the light clock than Jack's light takes. Nothing there contradictory to SR."
What? Jack sees nothing of the sort. He deduces all that from untested premises.
Assuming the two sets of mirrors are the same distance apart, Jack would see the light beam hit the top of his mirror at the same time it hit the top of her mirror, and see it then hit the bottom of his mirror at the same time it hit the bottom of her mirror. The duration would be the same.
If he perceives her light to have travelled farther in the same amount of time than his travelled (one way to look at it), then he could only conclude that, within his own frame of reference, the speed of light is not constant. He just saw two different light beams travel different distances in the same duration. She would see it the same way--different speeds of light in her own frames. Again, this supposes they just look at their clocks, instead of deducing time and distance from an a priori postulation of what it MUST be.
How could he conclude that light has different speeds within their own frame? Because now he has done the very thing that is strictly PROHIBITED by SR. He had used his frame to determine the speed of light on a moving object. He has "mixed frames" and has failed to obediently adhere to the strict "reciprocity of frames" requirement.
I said. "When Keating, et al, send a clock in motion, the one moving comes back reading less time."
You said: "As expected, but again dodging the point rather than responding to it."
What fucking point? Your endless regurgitation of the relationalist propaganda you have swallowed?
Keating:
1. Two clocks, one moving, one not.
2. They end up reading different times.
3. Who is claiming that each clock runs slower than the other or is "seen" that way by anybody? A 5:00 vs a 5:05 reading on two different clocks is seen that way by everybody who sees them. Or are you talking about how some delusional psychotic might see them? It's not a question of deducing time from a theoretical light clock by assuming your conclusion as your premise. It's readings on two actual clocks.
One Brow said: "I see it a an excellent example that I do acknowledge my mistakes, when I get a good explanation of why they need to change. You have failed to provide a good explanation."
Well, I think you see it wrong. On that occasion I repeatedly explained to you why you were wrong. You refused to listen to a word of it. You simply told me repeatedly that I just didn't understand statistics, and you did. It was only after some guy working on his doctorate in physics pronounced you wrong that you felt obligated to fess up. Even that guy first pronounced that you were right.
But when I questioned his assertion, and undermined it with my question, he listened. He reconsidered. He re-read the scenario. And then he said you were wrong.
The simple question I asked him was like this: "If the odds of flipping three heads in a row is 7 to 1, and I have just flipped two straight heads, are the odds of me now flipping heads once again 7 to 1?" He saw the point. When I asked you the same question you ignored it, told me to look at your computer simulations, and basically assumed that you can never be wrong.
aintnuthin said...
For you to even ask this question reveals that you don't know what a "concept" is.
A "concept" can be much more than "just an abstract concept". Try to respond to what I write. If you're saying that time is not just an abstract concept, but that there is some physical phenomenon of time measured by clocks (just as their is a physical phenomenon of distaqnce measured by yardsticks), then it's not just an abstract concept.
No, I'm not talking about an expression of ontological fact, I'm talking about the logical structure of a purportedly "physical" theory of motion.
Then, you shold be better able to understand the difference between making a valid claim of a particular state being at rest (a part of the logical structure) and a assumption that something is really at rest (an ontological claim). Instead, you keep using teh second as the first.
The theory, qua theory, requires that each observer presume that he is motionless and that all other things are moving with respect to him when evaluating the speed of light as being either constant or not.
The theory, as a theory, works equally well no matter which rest frame you claim is a valid rest frame, and not matter what you assume is the ontological truth of that claim.
The "speed of light" can only be "constant" if every observer makes an assumption about the other observer which opposes and contradicts the assumption that the other observer makes about that same matter.
The constancy of light does not change, regardless of whether a person uses their own intertial state or a different inertail state as a baseline for the measurements, as long as the use of that state is consistent. It's only by switching inertial states mid-stream that you get a non-constant speed, which is standard SR.
As soon as both I (on the train) and you (on the embankment) actually AGREE on who's moving, then SR is off.
Our agreement, or refusal to agree, does not change SR or its applicability in the slightest. Weren't you complaining to me that I was too subjectivist?
That's what the theory requires. It certainly is not an "ontological fact" that both are simultanously moving and both are simultaneously not moving. That's just what the theory requires you to assume about two observers.
Again, you've confused a valid claim with a statement of ontological fact.
One Brow said: "Jack sees his light and Jill's light going at the same speed, and Jill's light taking longer to make the transition within the light clock than Jack's light takes. Nothing there contradictory to SR."
What? Jack sees nothing of the sort. He deduces all that from untested premises.
Incorrect. Jack can directly compare the light in his clock, and it's path, with the light in Jill's clock, and it's path. Jack sees Jill's light take longer than his own light.
Assuming the two sets of mirrors are the same distance apart, Jack would see the light beam hit the top of his mirror at the same time it hit the top of her mirror, and see it then hit the bottom of his mirror at the same time it hit the bottom of her mirror.
Incorrect. Jack sees the light go top-to-bottom faster in his clock than top-to-bottom in Jill's, because the light travels over a longer distance, at the same speed. Remeber, it's been experimentally verified that the speed of light does not change based on the speed of the emitter.
What fucking point? Your endless regurgitation of the relationalist propaganda you have swallowed?
Keating:
Two clocks start in the same frame. ONe clock leaves the frame and returns to it. It shows less time passed. Standard SR.
Your point: while the plane was in the air, there was a mutual, non-reciprocal way of seeing that the clock in the air was running slower, and the one on th eground was running faster.
My point: if that is true, then when the plane passes over the clock on the ground, there should be an at-that-moment detectable way to show that the ground clock really looks to be running faster to the people in the air.
3. Who is claiming that each clock runs slower than the other or is "seen" that way by anybody?
Not you. It is a natual, straight-forward result of your claims that you are avoiding saying.
Well, I think you see it wrong. On that occasion I repeatedly explained to you why you were wrong.
You did so poorly, at least for me. densuprun described it in a manner I understood better. It's always hard for someone trying to teach something to acknowledge to themselves they are not particularly good at conveying information in a way a different person can understand it. I go throught that with the occasional student.
If you think I am refusing to acknowledge error because of some personal animosity, ask colton about your interpretations. Or, try some other mainstream physicist. Link me in so I can watch.
I said: "The internal contradiction is apparent to anyone who cares to think about it. That is the flaw in the theory."
That is not precise either. That is not a flaw in the theory, because, strictly speaking, the theory itself does not require that. That's only "required" by relationalist parasites who seek to claim that SR "proves" their philosophical position.
Al had extremely strong relationalist sympathies when he came out with SR, and had no problem saying that each observer's position was "equally valid" and in pretending that there was no 'preferred frame" in SR. But neither is correct in terms of what the theory itself (apart from "explanations") holds.
1. SR predicts what it predicts, and Al himself explained that rods and clocks must become deformed with motion in order for all observers to "see" light as travelling at the same speed. This is just another way of saying that they would NOT "see" it that way if they weren't using distorted measuring instruments. Later, he explicitly disavowed the positivist claim that "what you measure is what is true."
2. There is, and always was, a "preferred frame" in SR. It's not one frame for all observers, everywhere, just as it never was in classical physics, either. It is the frame with "proper length" and "proper time." It is only because there is a preferred frame that the travelling twin can "really" (rather than just apparently) age more slowly.
One Brow said: "Incorrect. Jack sees the light go top-to-bottom faster in his clock than top-to-bottom in Jill's, because the light travels over a longer distance, at the same speed. Remeber, it's been experimentally verified that the speed of light does not change based on the speed of the emitter."
How has it been "expermentally verified?" Certainly not by THIS example. There is no question of "relativity of simultaneity" for remote events involved here. All observers, wherever located, see two events which happen at the same time and at the same place (such as a light striking a mirror) as simultaneous, however they are located.
In these types of examples, no one claims that Jack sees the light striking her mirrors as "being slow" or different. The claim of a "time" difference simply comes from the fact that he perceives the other's light to TRAVEL farther in the same amount of time. If the speed of light is to be constant, then it MUST have taken more time. But the "more time" is imputed to the other's frame, not one's own. Time for Jack doesn't change just because he assumes it did for Jill. That's why he can't compare his clock to hers and get the desired answer. He must assume he already knows the answer, and then deduce a time change for her.
aintnuthin said...
Al had extremely strong relationalist sympathies ...
Yawn. I'm not a relationalist.
... rods and clocks must become deformed with motion ...
Only in the sense that the deformation is due to the differences in motion, and not a fature of teh rods and clocks spcifically.
It is only because there is a preferred frame that the travelling twin can "really" (rather than just apparently) age more slowly.
You mean, in some non-preferred frame that exists only as a mathematical construction within SR, the traveling twin does not age more slowly? What frame is that?
On the other hand, if the traveling twin ages more slowly in every frame so constructed, why does the notion of a preferred frame become relevant?
One Brow said: "Your point: while the plane was in the air, there was a mutual, non-reciprocal way of seeing that the clock in the air was running slower, and the one on th eground was running faster."
No, not my point at all. There is no practical way of "seeing" an earth clock while the plane was in the air. What is your point? That, while it's in the air the clock on the plane reads 5:05 while the one on the ground reads 5:00, but that, as soon as it lands, both clocks reverse themselves and the plane clock reads 5:00, while the earth clock changes to 5:05?
One Brow asked: "On the other hand, if the traveling twin ages more slowly in every frame so constructed, why does the notion of a preferred frame become relevant?"
You tell me. Why is it always the "moving clock" which runs slower? How do you know which one is "really moving" (i.e., which frame is "preferred" for the purpose of ascertaining which one is really moving)? By seeing which one ages less, that's how. It's not that SR says 'it could be either one." It doesn't. It is the MOVING clock, and only the moving clock, which slows down.
How has it been "expermentally verified?"
http://en.wikipedia.org/wiki/Emission_theory
Certainly not by THIS example.
Duh. Thought experiments do not bverify.
There is no question of "relativity of simultaneity" for remote events involved here. All observers, wherever located, see two events which happen at the same time and at the same place (such as a light striking a mirror) as simultaneous, however they are located.
Jack observes Jill's light to relect slower between the plates than his own light does, because Jill's light moves further.
In these types of examples, no one claims that Jack sees the light striking her mirrors as "being slow" or different. The claim of a "time" difference simply comes from the fact that he perceives the other's light to TRAVEL farther in the same amount of time.
Wrong. Travel farther, taking more time. This is a very basic result of Lorentz' equations.
If the speed of light is to be constant, then it MUST have taken more time. But the "more time" is imputed to the other's frame, not one's own. Time for Jack doesn't change just because he assumes it did for Jill. That's why he can't compare his clock to hers and get the desired answer. He must assume he already knows the answer, and then deduce a time change for her.
The time changed deduced for Jill is not the basis for Jack's ability to visually observe that the light bounces back and forth in his clock more quickly than in Jill's.
One Brow said: " It's always hard for someone trying to teach something to acknowledge to themselves they are not particularly good at conveying information in a way a different person can understand it...blah, blah"
Heh, straight back to the "I'm such a highly skilled expert that crude beings such as yourself can't even begin to communicate with me" stance, eh?
Well, Mr. know-it-all expert, see if you can understand, and correctly answer, one simple question, eh?:
If the odds of flipping three heads in a row is 7 to 1, and I have just flipped two straight heads, are the odds of me now flipping heads once again 7 to 1?
aintnuthin said...
There is no practical way of "seeing" an earth clock while the plane was in the air. What is your point?
So, you agree the experiment is possible, but just not practical?
My point is that this is an experiemnt that can distinguish mainstream SR from what you are proposing.
One Brow asked: "On the other hand, if the traveling twin ages more slowly in every frame so constructed, why does the notion of a preferred frame become relevant?"
You tell me.
My answer is that it is not relevant.
Why is it always the "moving clock" which runs slower?
Are you using "moving" as a claimed state or an ontological state here?
How do you know which one is "really moving" (i.e., which frame is "preferred" for the purpose of ascertaining which one is really moving)? By seeing which one ages less, that's how.
What if the difference in ages is always the same, regardless of what the moving state happens to be?
It's not that SR says 'it could be either one." It doesn't. It is the MOVING clock, and only the moving clock, which slows down.
Again, are you saying that SR will give a different answer depending on whether or not the unaccelerated twin is "really moving"? You dodged that question, try answering it instead.
aintnuthin said...
Heh, straight back to the "I'm such a highly skilled expert that crude beings such as yourself can't even begin to communicate with me" stance, eh?
No, that's not what I was saying at all. I communicate with students who have far less knowledge than you in math every day. Interesting that you would take it that way. What do you think your inferral says about you?
"Jack observes Jill's light to relect slower between the plates than his own light does, because Jill's light moves further."
BECAUSE it is perceived (by him, but not her) to TRAVEL further, you say. That's exactly what I said. Time hasn't changed for him, the distance has.
One Brow said: "The time changed deduced for Jill is not the basis for Jack's ability to visually observe that the light bounces back and forth in his clock more quickly than in Jill's."
He does NOT visually observe this, hence the need for labyrinthian, circuitous "explanations" for why he "concludes" that her clock is slow. Again, you merely demonstrate how easily students can be fooled.
Show me a physicist who says that Jack "sees" the light leaving and returning to her top mirror in any different duration than Jill sees it. It's not the duration between those events which causes a "time" difference in these examples. It is the "longer distance" supposedly travelled.
One Brow said: "Wrong. Travel farther, taking more time. This is a very basic result of Lorentz' equations."
You mean the Lorentz equations formulated by Lorentz? The guy who said that time does NOT change from frame to frame (but only the perception does) and whose theory has been repeatedly confirmed to precisely the same degree that SR has? Those Lorentz equations?
One Brow asked: "Are you using "moving" as a claimed state or an ontological state here?"
SR treats it as an ontological status. The travelling twin "really," not just apparently, ages slower, per SR. Might not be true, but, if it aint, then SR aint.
Dingle and Mach say it can't be true, because they would have to age the same. As would any good relationalist. And they too would mean it in an ontological sense, oddly enough.
One Brow said: "Again, are you saying that SR will give a different answer depending on whether or not the unaccelerated twin is "really moving"? You dodged that question, try answering it instead."
Are you trying to claim some difference between acceleration and movement in this case? For Newton, which SR reduces to in most cases, F=MA. So, if I bash a baseball with great force, it "acclerates," but doesn't move, that the idea?
I swear, Eric, you think all issues can be decided by the linguistic defintions you choose to create and apply, without regard to the context.
One Brow asked: "Again, are you saying that SR will give a different answer depending on whether or not the unaccelerated twin is "really moving"?"
I'm saying that exactly what SR says, yeah. Al, and about every physicist I've seen address the question, merely refer to the "moving" clock (but actually mean the accelerated clock, as I understand it--the same thing in this case).
One Brow asked:"What if the difference in ages is always the same, regardless of what the moving state happens to be?"
In that case, you, Mach, Dingle, and all the other relationalists would be correct. The difference would always be the same--it would always be zero difference.
One Brow said: "So, you agree the experiment is possible, but just not practical?
My point is that this is an experiemnt that can distinguish mainstream SR from what you are proposing."
To the extent it can be tested it has been tested by the Keating type experiments. Turns out, only one clock (the moving clock) actually runs slower. They do not both run slower than the other, and both reading an earlier time than the other.
Who's the one ducking questions here? What reason do you have to even begin to think that the situation is reversed for the moving clock while it is in the air, and that both clocks magically reverse time when it lands? Why would anyone on a plane think that, or see that, assuming such an experiment was practical? Clocks are mechanical devices giving read-outs, right or wrong. A slow clock will "tell" you that it's only 5:00 when it's actually 5:05. But it does not base it's readings on deductions or upon the subjective desire to strict comply with the unsubstantiated claims of relationalists.
One Brow said: "Only in the sense that the deformation is due to the differences in motion, and not a fature of teh rods and clocks spcifically."
You just keep telling yourself that, eh? If you say it enough times, it will certainly be true. Dingle, like all good relationalists, insists that any such changes are strictly an illusion, as you do. They don't really happen, and, of course, as a consequence, there can be no real age difference.
Unfortunately, Hogg, Al, and others say the changes must be real, not illusory. Real "physical" (not perceptual) changes, they say. They could be wrong. In that case, SR is wrong, and you are right. But how can you claim SR is right AND that you are right?
It's all about "inertial frames pointing away" and objects taking "different paths through time," you say. These explanations have exactly ZERO physical content. Analogies to "tilted yardsticks" and "shadows" explain nothing. If the clocks do not really slow down, and the rods really contract, then SR is wrong. Saying SR is right, because, as only you, but not SR theorists know, it's really all just an illusion does not display much understanding of the concepts or theory at issue, I'm afraid. If the effects are illusory, then (1) it's not a theory about physics, and (2) any claim that the speed of light is perceived to be constant is illusory and simply wrong.
Insisting that perceptual changes cause "real, physical changes" in external objects does not display even the most rudimentary understanding of the difference between physical changes and perceptual changes caused by a changed perspective. Of course, since you don't understand this, you see no difference, and therefore there is no difference to be understood.
One Brow said:
"http://en.wikipedia.org/wiki/Emission_theory"
1. Denial of the adequacy of an emission theory (which only relates to the speed of light being independent of it source, and does not address the question of light also being independent of the motion of the receiver) does not establish the "truth" of SR. That is only one-half of the SR postulates. The mere assumption that light does not travel at a speed that is relative to it's emitter says nothing about how the speed of light would be perceived by a moving observer.
Although your wiki article refers to "confirming special relativity," one should be clear about what is intended by that. And the article makes it clear that by "special relativity" they only mean the "independent of the speed of the source aspect" of SR. It says, for example: "...confirms special relativity, i.e. the source independence of light speed. This experiment was executed in vacuum, thus extinction effects play no role."
2. The article which you cite claims that after Fox made what he (Fox) called "a simple and natural modification of the (Ritz) hypothesis concerning the velocity of radiation," then the resulting theory "is in harmony with the electron theory of dispersion, accounts satisfactorily for aberration, the first-order Doppler effect from moving sources and interferometer experiments on binary stars. There is no evidence from binary stars which contradicts it. It is compatible with the second-order Doppler effect and possibly the Fizeau experiment since arguments are advanced which indicate that these phenomena depend essentially on the momentum and energy of radiation." Not every emission theory is the same, to begin with.
3. Whatever the ultimate merits of an "emission theory," those considerations have no bearing on the "light clock comparison" example used the the professor which we have been discussing.
Typical relationist propaganda infiltrating "explanations" of time dilation, eh?:
"When two observers are in relative uniform motion and uninfluenced by any gravitational mass, the point of view of each will be that the other's (moving) clock is ticking at a slower rate than the local clock. The faster the relative velocity, the greater the magnitude of time dilation. This case is sometimes called special relativistic time dilation. It is often interpreted as time "slowing down" for the other (moving) clock. But that is only true from the physical point of view of the local observer..."
If it's "only true from the physical point of view (a "point of view" is not a physical thing, but let's ignore that) of the local observer, then the travelling twin could not "truly" age less (because for him, it is "true" that his clock is correct and that earth's clock have "truly" slowed down--if you listen to the relationalists). Isn't that much obvious? It goes on to say:
"The point of view of the other observer will be that again the local clock (this time the other clock) is correct and it is the distant moving one that is slow...the point of view of each will be that the other's (moving) clock is ticking at a slower rate than the local clock."
http://en.wikipedia.org/wiki/Time_dilation
All this is saying is that each observer "will" assume that he is motionless and that any other clock he sees is the one "moving." It is always the "moving clock" which is slower, but both claim that the "other" clock is the one moving. But, again, those "assumptions" are mutually exclusive. If one does not assume that he is motionless, then he will not "see" the other clock to be the one which is moving. In that case, his clock will be the moving clock, and he will have to conclude that HIS (not the other guy's) clock is the one which slowed down.
Could it be any more obvious where the claim that each observers "sees" the other's clock as slow orginates from? They "see" no such thing, they deduce it from the assumption that they are motionless(which SR says they must do). But again, it can't be "truth" that both are motionless when they're moving relative to each other.
Of course, it would only be "obvious" to one who was willing to reflect on the matter. Without thought, nothing is "obvious." The claim that the spirit world causes observers to see clocks slowing down would not be "obviously" true or false to one who does not reflect on the ramifications of it all.
You might notice that this same article also purports to explain time dilation by virtue of a difference in perception of distance travelled (only). In the example, the time elapsed does not change for each observer, only the perception of distant travelled. If one assumes that the speed of light is constant, then one must assume that time is "different" in the other frame. Why? Because he doesn't think it travelled as far in the SAME AMOUNT of time. But it MUST travel the same distance in the same amount of time. Why? Because Al posits that, that's why! So, the "same" amount of time must necessarily be less for the "other guy." How else could the principle of relativity (speed of light is perceived to be the same in all inertial frames) be possible?
This is exactly what Al says in his own words (which I have previously quoted). He says, in effect, that if you want to say that the speed of light is perceived to be constant, then you MUST say that time (and distance) has changed in that other frame. Why has it "changed?" Because, per Al the measuring instruments have changed. Changed clocks and rods result in changed perceptions of time elapsed and/or distance travelled. In effect, he's only saying that it is MEASURED to be constant, not that it actually IS constant. If you said the instruments had not changed, then you could not achieve the perception of an identical speed of light in inertial frames moving at different speeds relative to each other.
Read the article critically, instead of as a cheerleader and "yes man" for the "truth" of SR. With respect to time dilation it also contradicts itself.
1. On the one hand, it trys to suggest that the relativity of simultaneity somehow explains things. "...the question of whether something happening at one location is in fact happening simultaneously with something happening elsewhere, is of key importance. Calculations are ultimately based on determining which events are simultaneous. Furthermore, establishing simultaneity of events separated in space necessarily requires transmission of information between locations, which by itself is an indication that the speed of light will enter the determination of simultaneity."
So, now, the transmission speed of light affects calculations of time elapsed in another frame, eh? How so, in any way relevant to the calculation of elaped time? It doesn't. This same article aknowledges that when it says...
2. "From a local perspective, time registered by clocks that are at rest with respect to the local frame of reference (and far from any gravitational mass) always appears to pass at the same rate." So the time on a stopped train would be the same as ours even if it were a million miles away. The rate of time passage is NOT affected by a separation in distance.
It always much easier to "explain" things when you can have it BOTH (or, really, ALL ways) just depending on what point you are trying to explain at the time, eh? As long as consistency is not a factor. I can just as easily explain to adults that Santa Claus does NOT really exist as I can explain to kids that Santa Claus DOES really exist. Piece of cake, as long as I figure consistency be damned.
One other statement of interest in this article is this: "As there is no such thing as absolute motion in relativity (as is also the case for Newtonian mechanics), both the green and the red fleet are entitled to consider themselves motionless in their own frame of reference."
This makes a couple of points:
1. There is no absolute motion in Newtonian mechanics, either, so SR did not suddenly come up with a whole new "reality" about space and time based on the lack of absolute motion.
2. Assuming that each observer is "entitled to consider themselves motionless" cannot open up the possibility that both ARE motionless (as SR insists you must assume if the relativity principle is to be "true"). Even if the geocentric hypotheses is "equally valid" as contrasted with a heliocentric one, the fact remains that the earth cannot revolve around the sun while the sun simultaneously revolves around the earth. Even Mach understood that.
It's one thing to say you can't know which one is moving (even if you can), and another to say both are true. If you merely say you can't know, you disregard all physical theories of motion as metaphysical hogwash, and go on about your way. If you say both are true, because they are equally "entitled" to be true, then you are in serious need of some logic lessons. John and Mary might both be "entitled" to eat the whole damn pie Mom baked, but they can't both actually eat the whole damn pie.
aintnuthin said...
One Brow said: "The time changed deduced for Jill is not the basis for Jack's ability to visually observe that the light bounces back and forth in his clock more quickly than in Jill's."
He does NOT visually observe this,
Sure he does. What prevents him from seeing it?
Show me a physicist who says that Jack "sees" the light leaving and returning to her top mirror in any different duration than Jill sees it.
What is "different duration" supposed to mean here? That Jack measures Jill's light to take at 1.001 picosecond while Jill sees 1 picosecond? Standard SR/LR/LET. Otherwise, I have no idea what you mean.
Those Lorentz equations?
They are the same equations in mainstream SR and in LET.
One Brow asked: "Are you using "moving" as a claimed state or an ontological state here?"
SR treats it as an ontological status.
Mainstream SR treats is as a claimed state.
The travelling twin "really," not just apparently, ages slower, per SR.
Yes, that is mainstream SR.
Dingle and Mach say it can't be true, because they would have to age the same. As would any good relationalist.
As does LET, for that matter. In LET, the twins went through the same amount of time, and so are the same age, despite their different appearances. Only in mainstream SR is one twin actually younger.
One Brow said: "Again, are you saying that SR will give a different answer depending on whether or not the unaccelerated twin is "really moving"? You dodged that question, try answering it instead."
Are you trying to claim some difference between acceleration and movement in this case?
I'm not sure how to answer that. Acceleration is one facet of movement. It is not inertial movement.
For Newton, which SR reduces to in most cases, F=MA. So, if I bash a baseball with great force, it "acclerates," but doesn't move, that the idea?
Depends on whether you were moving backward when you bashed the ball. If you're moving backward at 100 mph, and you normally bash a ball at 100 mph forward, the ball doesn't move backward or forward.
I swear, Eric, you think all issues can be decided by the linguistic defintions you choose to create and apply, without regard to the context.
Yet, I'm the one constantly inserting proviso and conditions into answers, because I want to avoid that very thing.
One Brow asked: "Again, are you saying that SR will give a different answer depending on whether or not the unaccelerated twin is "really moving"?"
I'm saying that exactly what SR says, yeah.
Then you're wrong. If both twins are moving, and the accelated twin pulled up to a stop, and then caught up to unaccelerated twin, the accelerated twin *still* ages less. Standard, mainstream, SR. You get the same answer whether the non-accelerating twin is moving or not.
One Brow asked:"What if the difference in ages is always the same, regardless of what the moving state happens to be?"
In that case, you, Mach, Dingle, and all the other relationalists would be correct.
I'm discussing relativity, not relationalism.
The difference would always be the same--it would always be zero difference.
Incorrect. The accelerated twin always ages less by the end of the scenario, the only time they can be compared without bias.
One Brow said: "So, you agree the experiment is possible, but just not practical?
My point is that this is an experiemnt that can distinguish mainstream SR from what you are proposing."
To the extent it can be tested it has been tested by the Keating type experiments.
Incorrect. The Keating experiment only compared clocks after the jet had landed, when they were both in the same inertial state again. It did not compare how observers on the ground saw the clocks in the air run whil the plane was in flight, nor how observers on the plan say the clocks on the ground run. Again, that would be a fairly simple way to test your theory against standard SR.
Who's the one ducking questions here?
Name one question I haven't answered, that did not depend on the false notion I am promoting relationalism.
What reason do you have to even begin to think that the situation is reversed for the moving clock while it is in the air, and that both clocks magically reverse time when it lands?
I don't think that.
Why would anyone on a plane think that, or see that, assuming such an experiment was practical?
I'm not asking what they think, just what they observe.
Clocks are mechanical devices giving read-outs, right or wrong. A slow clock will "tell" you that it's only 5:00 when it's actually 5:05. But it does not base it's readings on deductions or upon the subjective desire to strict comply with the unsubstantiated claims of relationalists.
Exactly.
You just keep telling yourself that, eh?
Since it's true, I will.
Dingle, like all good relationalists, insists that any such changes are strictly an illusion, as you do.
Except, I don't claim they are an illusion.
Unfortunately, Hogg, Al, and others say the changes must be real, not illusory.
As do I.
Real "physical" (not perceptual) changes, they say.
Exactly.
They could be wrong. In that case, SR is wrong, and you are right. But how can you claim SR is right AND that you are right?
Because I am defending and explaining mainstream SR.
It's all about "inertial frames pointing away" and objects taking "different paths through time," you say. These explanations have exactly ZERO physical content.
Incorrect.
Analogies to "tilted yardsticks" and "shadows" explain nothing.
Analogies are for the purpose of vizualization, not explanation.
If the clocks do not really slow down, and the rods really contract, then SR is wrong.
They do slow down and contract, as a matter of the system, and not due to effects local to the rod or clock. That's one reason the effects are reciprocal.
Saying SR is right, because, as only you, but not SR theorists know, it's really all just an illusion
I don't think it's an illusion.
Insisting that perceptual changes cause "real, physical changes" in external objects
I don't think the changes are solely perceptual, but are real changes based in physical phenomena. I believe we agree they are perceptual in that they can be perceived.
Of course, since you don't understand this, you see no difference, and therefore there is no difference to be understood.
I'm tired of pointing out that I don't think the effect is illusory. Very tired. I'm done responding to those claims. If you still don't understand the difference between an illusionary effect and real physical effects based on the juxtapositon of different objects, it might just be a failure of my ability to descibe them, or it might not. Either way, I'm not going to bother to continue in this thread.
1. Denial of the adequacy of an emission theory (which only relates to the speed of light being independent of it source, and does not address the question of light also being independent of the motion of the receiver) does not establish the "truth" of SR.
Of course not. It was only offered to show Jack sees Jill's light as traveling at the same speed he sees his own light traveling at.
, then the travelling twin could not "truly" age less (because for him, it is "true" that his clock is correct and that earth's clock have "truly" slowed down--if you listen to the relationalists). Isn't that much obvious?
It's not only not obvious, it's wrong in mainstream SR. I don't care what relationalism says.
All this is saying is that each observer "will" assume that he is motionless and that any other clock he sees is the one "moving." It is always the "moving clock" which is slower, but both claim that the "other" clock is the one moving. But, again, those "assumptions" are mutually exclusive.
Since no one person is making both of those assumptions (as a valid assumption) at the same time, their mutual exclusivity is not relevant.
If one does not assume that he is motionless, then he will not "see" the other clock to be the one which is moving.
Why should his assumptions prevent him from seeing a clock move more slowly? What blocks his vision?
Could it be any more obvious where the claim that each observers "sees" the other's clock as slow orginates from? They "see" no such thing,
What stops them from comparing clock motions?
The claim that the spirit world causes observers to see clocks slowing down would not be "obviously" true or false to one who does not reflect on the ramifications of it all.
This coming from a person who puts a magical impedence into the ability of one person to see the clock of another person.
You might notice that this same article also purports to explain time dilation by virtue of a difference in perception of distance travelled (only).
It uses that reasoning to describe what is expected to be a visible effect.
Read the article critically, instead of as a cheerleader and "yes man" for the "truth" of SR. With respect to time dilation it also contradicts itself.
*chuckle*
So, now, the transmission speed of light affects calculations of time elapsed in another frame, eh?
No, questions of simultaneity. In standard SR, the same amount of time elasped for two different things can result in non-simultaneous events. For example, assuming the twin are 20 when the journey starts and the unaccelerated twin is 30 when it finishes, the twins no longer celebrate their 40th birthday at the same time. Time elasped is a different thing.
The rate of time passage is NOT affected by a separation in distance.
Corrrect.
It always much easier to "explain" things when you can have it BOTH (or, really, ALL ways) just depending on what point you are trying to explain at the time, eh?
It's much easier to dismiss things when you conflate different concepts like "simultaneous" and "equal time elapsed".
It's one thing to say you can't know which one is moving (even if you can), and another to say both are true.
It's yet another, distinct thing to say both positions are equally valid.
One Brow said: "Try to respond to what I write. If you're saying that time is not just an abstract concept, but that there is some physical phenomenon of time measured by clocks (just as their is a physical phenomenon of distaqnce measured by yardsticks), then it's not just an abstract concept."
You don't understand what's being responded to, or what the response even is, despite us going over it many times. Recall Newton's distinction between true (conceptual) time, and "apparent, common, and relative time" (time as measured, with the concept as a guiding exemplar). Al discussed the same thing in his response to the positivists.
Newton never believed that "time" was anything other than a necessary concept. Likewise, Newton did not use the concept of "absolute space" to establish "absolute motion." Mach, following Hume, Liebniz, Berkeley, and other relationalists, insisted that space was a "fiction" that could not properly be resorted to explain motion or the separation of physical objects. A strictly philosophical view, one which disintegrates upon analysis and which is "violated" by it's own advocates.
At that time Al bought into Mach's call for the banishment of "absolute space" from physics, and actually boasted that he had done so. He hadn't. It was never part of physics to begin with, except as a conceptual background necessary for context. To the extent Newton relied on "absolute space" to explain things, Al did also, to that same extent. Al later stated his regret about over-reaching with his claims about abolishing the ether, absolute space, and absolute motion.
If nothing in SR can be said to be really moving, how about light? Does it move? Does it have a certain known, and immutable speed? And what is that speed "relative to?"
It is relative to frames of reference, those "things" that are always motionless with respect to all other objects in the universe, know what I'm sayin? Those things that point, and tilt, etc. Like arrows of time pointing downward to create gravity. Who knew the reason I can't dunk on an 11-foot basket was all on account of arrows on a piece of graph paper holding me down, eh? Time is what keeps me earthbound. They all make the same amount of physical sense, which is to say nada, zilcho, no seegar. If you want to talk about time having power, then you're much better off talking to mathematicians who think their concoctions actually cause events in objective physical reality. Newton would have been aghast at such nonsense.
One Brow said: "Depends on whether you were moving backward when you bashed the ball. If you're moving backward at 100 mph, and you normally bash a ball at 100 mph forward, the ball doesn't move backward or forward."
If I make contact with the ball, it will accelerate away from me whether I'm going 0 MPH or 10 million MPH at the time I hit it. By the way, what absolute frame of reference are you using to come up with this perspective?
One Brow said: "If both twins are moving, and the accelated twin pulled up to a stop, and then caught up to unaccelerated twin, the accelerated twin *still* ages less. Standard, mainstream, SR. You get the same answer whether the non-accelerating twin is moving or not."
I have no idea of what you are trying to say here that is relevant to the question. Are you trying to say that the one twin ages slower only during such times as he is actually going at a higher rate of speed? That's a given, and has nothing to do with which twin ages less when he ages less. If your last reference is somehow to Al's desperate resort to fictitious gravitational fields, that "account" is rejected by modern physicists, as I have quoted them as saying. Physics does not deal with fantastical fictitious gravitational fields, they rightfully say.
One Brow said: "Why should his assumptions prevent him from seeing a clock move more slowly? What blocks his vision?"
Vision!? It's not a matter of vision, can't you understand this? Show me one person who ever claims to have "seen" time moving slower in another inertial frame. That is not the claim. The claim is simply about what a person will deduce if he adheres to the theoretical dictates of SR.
One Brow said: "Incorrect. The Keating experiment only compared clocks after the jet had landed, when they were both in the same inertial state again."
And exactly how is this supposed to make a damn bit of difference? Again, are you claiming, that while flying, the clock on the plane was moving faster, but reversed itself when it landed? What difference does it make? Please explain how and why that matters in the least. If I'm a clock on the plane, and I'm displaying a time of 5:00 while the (previously synchronized) earth clock is displaying 5:05, why would I claim THAT clock is running slower, instead of me?
One Brow said: "What is "different duration" supposed to mean here? That Jack measures Jill's light to take at 1.001 picosecond while Jill sees 1 picosecond? Standard SR/LR/LET. Otherwise, I have no idea what you mean."
Simple. Forget about Jill's frame for a minute. If Jack simply looked at both clocks (his and Jill's) from his frame, the light beams he sees in both clocks will each hit the top and bottom mirrors (respectively) at the same time, hers will just travel farther (for him) in that time. That duration is the same, however measured.
Since, according to him, hers travelled farther, it could simply be seen as a case where he saw two light beams travelling at different speeds in his own frame. The speed of light would not be constant.
But he doesn't compare the clocks. He deduces what Jill must see while ignoring what he could see, but refuses to look at. Instead he deduces all distance from time, and all time from distance. Always with the assumption that he already knows what the speed of light is in both frames.
Jack does not "see," and no professor or anyone else claims he "sees," her light hitting the mirrors at any different time than the light in his clocks does. It's all a deduction from untested premises. Wiki on the topic:
First: "Consider a simple clock consisting of two mirrors A and B, between which a light pulse is bouncing. The separation of the mirrors is L and the clock ticks once each time it hits a given mirror."
So the distance between the mirrors remains constant, and the clock ticks when it hits the mirrors.
Now: "From the frame of reference of a moving observer traveling at the speed v (diagram at lower right), the light pulse traces out a longer, angled path."
So, while the time (the number of ticks, which is the number of times the light hits the mirrors) remains unchanged as between the two observers. But the distance the light travels between those two ticks changes (not the number of ticks--if you think otherwise, look it up). From there it's all a matter of deduction from premises dictated by SR, not by comparing durations.
Wiki expressly acknowledges that the "lengthening of the period of this clock" is "implied" (not observed) by Al's postulates. Once you make all these assumptions, it's a simple matter to "show" the assumed changes in a "computer simulation" while claiming the simulation "demonstrates" this truth of the assumption.
But in this professor's example, Jack doesn't compare his clock to hers, or her distances to his distances. He sees her clock only register a given number of ticks (as his does, too). But now he uses distance as perceived from HIS FRAME (not hers) to deduce that her clock is slowed.
Likewise, when he deduces what lengths apply in her frame, he then, and only then, looks at his clock. Then he deduces her perceived lengths by using his time to deduce what her length has to be to equal c.
So, first he combines (1)time as measured by her clock, with his own distance measurements, and then, once again crossing frames, he combines (2) time as measured with his clock to deduce her distances. Something fishy here, ya think? Generally you measure time with a clock, not a ruler. Conversely, generally you measure distance with a ruler, not a clock. Only after all this convoluted cross-matching and deduction does he conclude that her clock must be running slower. Of course, she does the same with him.
What's overlooked is that his light only travelled one light second in his frame, and hers "travelled" 3 light seconds (or whatever the difference was). Therefore the speed of light is not constant for him if he uses his clocks to measure light in her frame. He may always measure light to be the same within his frame, but this does not hold when he calculates the speed of light in another frame.
aintnuthin said...
You don't understand what's being responded to, or what the response even is, despite us going over it many times. Recall Newton's distinction between true (conceptual) time, and "apparent, common, and relative time" (time as measured, with the concept as a guiding exemplar). Al discussed the same thing in his response to the positivists.
Is that similar to the distinction between true (conceptual) distance, and "apparent, common, and relative distance" (distance as measured, with the concept as a guiding exemplar). Because that's pretty much my understanding. If not, you'll have to be much more specific. In particular, is true (conceptual) time a physical phenomenon, in the manner that distance is a physical phenomenon, or not?
If nothing in SR can be said to be really moving,
Define "really moving". I don't recall your defintion.
how about light? Does it move?
Compared to anything that is not light, yes.
Does it have a certain known, and immutable speed?
Compared to any other object, light has a specific, immutable speed in a vacuum.
And what is that speed "relative to?"
Any other object.
Who knew the reason I can't dunk on an 11-foot basket was all on account of arrows on a piece of graph paper holding me down, eh?
No one claims that.
... mathematicians who think their concoctions actually cause events in objective physical reality.
I haven't met any such mathematicians. Some of them think numbers are real, some think they are not. Neiter view endorses the the notion that reality is changed by their concoctions.
One Brow said: "Depends on whether you were moving backward when you bashed the ball. If you're moving backward at 100 mph, and you normally bash a ball at 100 mph forward, the ball doesn't move backward or forward."
If I make contact with the ball, it will accelerate away from me whether I'm going 0 MPH or 10 million MPH at the time I hit it.
That's what I said.
By the way, what absolute frame of reference are you using to come up with this perspective?
I wasn't using one at all.
I have no idea of what you are trying to say here that is relevant to the question. Are you trying to say that the one twin ages slower only during such times as he is actually going at a higher rate of speed?
I'm saying that whether the unaccelerated twin is moving or not does not change the resolution of the twin scenario, at all.
That's a given, and has nothing to do with which twin ages less when he ages less.
I discerned no meaning from that sentence.
One Brow said: "Why should his assumptions prevent him from seeing a clock move more slowly? What blocks his vision?"
Vision!? It's not a matter of vision, can't you understand this?
Why do you want to exclude what people see from a discussion of what people observe? It's very strange.
Show me one person who ever claims to have "seen" time moving slower in another inertial frame. That is not the claim.
That is a claim of mainstream SR.
And exactly how is this supposed to make a damn bit of difference?
I'm proposing a test that would distinguish LET from SR. The test requires observation while in different intertial states. Talking about comparisons while in the same inertial state will not satisfy that test.
Again, are you claiming, that while flying, the clock on the plane was moving faster, but reversed itself when it landed?
I discerned no meaning in that question to which I could respond.
What difference does it make?
You don't think there is any value is confirming LET over SR, or vice-versa?
... why would I claim THAT clock is running slower, instead of me?
What you claim is irrelevant to this experiment.
Simple. Forget about Jill's frame for a minute.
OK.
If Jack simply looked at both clocks (his and Jill's) from his frame, the light beams he sees in both clocks will each hit the top and bottom mirrors (respectively) at the same time, hers will just travel farther (for him) in that time.
Wrong. Jack will see Jill's light take longer to make the trip. If Jack sees his bounce in 1 picosecond, Jill's might take 1.001 picosecond (depending upon Jill's speed relative to Jack). Remeber, Jack sees Jill's light travel a longer path than he sees his own light travel. This is the result in mainstream SR, in LET, in GR.
Until we clear that up, there's not much point in discussion the rest of the scenario.
But the distance the light travels between those two ticks changes (not the number of ticks--if you think otherwise, look it up).
You're relying on the absence of the wiki spefically mentioning the increased time to be evidence of no increased time. You are mistaken.
For example, check the caption to the second diagram in the wiki page on time dilation. Specifically, "Observer moving parallel relative to setup, sees longer path, time > 2L/c, same speed c." The time seen by the moving observer (or by the stationary observer of a moving platform) is longer than the time seen by the observer in the same inertial state as the clock.
One Brow said: "Because that's pretty much my understanding."
OK, mine too. Both time and distance are concepts (ideal mental constructions), they are not tangible "things." Rods and clock are said to "measure" distance and time, and they do, imperfectly or not. But the measurements are not distance or time, per se, and "measuring" time and distance does not make them any less abstract as concepts. For me the phrase "abstract concept" is really just a redundancy. There are no "concrete concepts" and concepts exist only as an abstraction.
You had said: "This is one of the problem areas of LET, for me. If time does not have a coporal existence, but is just an abstract concept, why should it be consistent from frame to frame?"
Time does not have a "coporeal existence," although clocks do. But that doesn't make time a physical thing, nor, of course, as the logical positivists want to say, does a yard define distance. Time and distance are both idealized concepts, and measuring something to be 22' 10 3/4" long does nothing to change that. The measurement is not distance itself (although we may commonly refer to it as a "distance"). Because concepts are idealizations, they NEVER change, and they certainly don't change from "frame to frame." They are not matters of "perception," because they are even perceivable by the senses.
So time, as a concept, could never change from frame to frame. Measurements of time could, but, again, they are not the "concept of time" (except for positivists, maybe, but we know about them). But you appear to have been influenced by the positivistic philosophy and show a number of positivistic leanings, I think.
You had said: "... the notions of "really moving" and asserting that they are "at rest" are not part of mainstream SR."
Then, we I ask a question about what you are trying to say, you tell ME to define it.
One Brow said: ""Define "really moving". I don't recall your defintion."
I trying to plumb your intended meaning, not mine. What did you mean by "really moving" when you denied that it was part of "mainstream SR?" And what did you mean by saying it's "not a part of?"
1. Did you mean SR does not purport to be Webster's and undertake to define common words, like "moving" and "real," or
2. Did you mean that SR rejects the notion that things can be "really moving?"
One Brow said: "I'm saying that whether the unaccelerated twin is moving or not does not change the resolution of the twin scenario, at all."
Still not clear what you are trying to say. As I've said many times, it is a matter of which one is moving "faster," and of course one can be faster than any other object that is also moving.
But are you trying to say that motion is irrelevant to which one ages more slowly?
One Brow said: "If both twins are moving, and the accelated twin pulled up to a stop, and then caught up to unaccelerated twin, the accelerated twin *still* ages less. Standard, mainstream, SR. You get the same answer whether the non-accelerating twin is moving or not."
What does this mean? What does "pulled up to a stop" mean? Does that mean he achieved a state of absolute motionlessness? From what frame of reference would he be seen to "stop?" I asked what your frame was, and you said there was none.
Kinda ironic after the thousands of times you have mentioned that "you have to specify a frame of reference."
I said: "All this is saying is that each observer "will" assume that he is motionless and that any other clock he sees is the one "moving." It is always the "moving clock" which is slower, but both claim that the "other" clock is the one moving. But, again, those "assumptions" are mutually exclusive."
You responded: "Since no one person is making both of those assumptions (as a valid assumption) at the same time, their mutual exclusivity is not relevant."
Wrong. Ontology aside, SR, as a theory, requires that if there are two relatively moving observers, each must AT THE SAME TIME, assume the other is moving. If they don't, the theory falls apart. If both the guy on the ground and the guy on the train agree that the train is moving, SR is done. For the theory to "work," both must simultaneously assume that the other party is moving.
One Brow said: "Until we clear that up, there's not much point in discussion the rest of the scenario....You're relying on the absence of the wiki spefically mentioning the increased time to be evidence of no increased time. You are mistaken.
Actually, I was relying on what Hogg had said, as I remembered it. When talking about light clocks and length contractions, here's what he says:
"Imagine that E observes D’s clock to tick 100 times during a journey from planet A to planet B, two planets at rest in E’s rest frame.
D must also observe 100 ticks during this same journey."
Got the picture so far? He says E (earth) will not see more ticks of the clock that D does, or vice versa. So it is not the NUMBER of ticks that is in question. If D's time dilation factor is 50%, he says E will not see 200 while D only sees 100. E's clock is not "ticking slower" than D's in this scenario, at least not as measured by the number of clock ticks.
So where's the time dilation? Hogg goes on:
"However, they do not agree on the rate at which D’s clock ticks."
Why not? He's going from planet A to B and everyone agrees on that. In the time it takes him to go from point A to point B, we both see 100 ticks of the light clock.
Because, says Hogg: "While E measures the distance between A and B to be = 100u ∆t, D measures it to be = 100u ∆t = /γ. Since
γ >1, D measures ashorter distance than E."
http://www.scribd.com/doc/12440845/Special-Relativity
So now we're at the scenario I was describing. Same number of clock ticks, but each observer has a different notion of how far the object travelled in that same duration. Again, when I say the "same duration" I simply mean that all parties agree on the moment he left planet A and on the moment he arrived at arrived planet B (after adjusting for the time it takes light to travel to get to us on earth). But since he thinks he travelled less distance in that same time, his clock must be slow.
It's all just one circular can of crap, really.
Truth be told, what Hogg is saying doesn't sound right to me. I'm not convinced that SR really holds that the number of clock ticks will be the same for each party as D goes from planet A to planet B.
But you hear so many poor, inconsistent, and varying explanations from various authorities, that you start to wonder if there is really any such thing as "mainstream SR." Everybody seems to have his own notion of what it holds, and his own way of trying to explain it.
Here's an apparent inconsistency from Hogg in this very example. He says: "In addition to agreeing on the number of ticks, Dand E also agree on their relative speed."
How can they agree on their relative speed if D always sees the distance separating him from E to be less? Because he also supposedly sees time as slower all due to length contraction? That would be the ultimate boot-strapping. And, if he does see the same relative speed, then they must not "really" be travelling at the same relative speed, because he is using instruments with different calibrations to arrive at the same speed we do. Which means that, underneath it all, the measurements are not "the same."
I said: "Truth be told, what Hogg is saying doesn't sound right to me. I'm not convinced that SR really holds that the number of clock ticks will be the same for each party as D goes from planet A to planet B."
What's he's saying does seem to make inherent sense, though. How could a traveller see light hitting his mirrors 100 times and we on earth see the light hitting his mirrors 200 times? We couldn't, not if we're looking at the same clock.
We could see our own light clocks ticking 200 times, and I left consideration of that possibility out of my post. Hogg does not explicitly say that we wouldn't, but it's implied. Why? Well...
1. In that case, you can't explain the "time dilation" by virtue of the length contraction, as he does here.
2. Then would D also see our clocks stike it's mirrors 200 times? If so, then where's the reciprocity? In that case:
A. We see our clock making 200 ticks, and his only 100, so his clock is slow, but...
B. He sees our clock making 200 ticks, but his only 100, so our clock is fast to him, not slow
One Brow said: "That can't be deternmined within SR. Fortunately, the answers to any physical problems are the same regardless of which assumption you make about things that are or are not moving."
There you go with your inconsistencies again, Eric. You make a pronouncement, then abandon and contradict it when it seems convenient.
How is (1) "the twin in the space ship aged less" the "same [answer] regardless of the assumptions you make" as (2) "the twin in the space ship ages MORE?"
This depends on the assumptions you make, and you will not get the same answer regardless. I can certainly understand that it IS the "same answer" in the sense that it is always the moving twin who ages less. But, not long back, you refused to acknowledge that this was a consistent prediction of SR. "Generic predictions" won't do, you said, only "specific predictions." If that's the case the "specific prediction" of which twin ages more definitely depends on the assumptions you make (which you now deny makes a difference).
I said: "Show me one person who ever claims to have "seen" time moving slower in another inertial frame. That is not the claim."
You responded? "That is a claim of mainstream SR."
It is? Who do they claim has "seen" it? Neil Armstrong, or someone like that? You mean they deduce, from their postulates, that that is what one would if he could see it, right? Which is just another way of saying it's their deduction, not their empirical knowledge.
The question for SR is, how can the twin "see" earth clock running slow when, in fact, HIS clock is running slow?
How can a guy in orbit, looking at a clock right next to him which reads 5:00 and then, using "binocuars" look at an earth clock which says 5:05, "see" the earth clock as running slower? How would that work, exactly?
That's the problem. Relationalists like yourself want to constantly shout from the rooftops that all effects are reciprocal between frames in SR while ignoring that, according to SR itself, they are NOT. Only the moving clock runs slower, not both clocks.
I've said this before but I'll say it again, because I want to ask you a question. The "relativity" principle is not new, by any means. It goes back hundreds of years to Galileo. Al did not discover a new truth about the universe in that respect.
Although using the principle to theoretically demonstrate the principle of inertia (a ball dropped from the mast on a moving ship does not "suddenly" lose it's forward momentum just because it is no longer "attached to" the ship), he noted that FROM WITHIN THE MOVING SYSTEM (only) one's own motion could not be detected.
Nobody ever took this as conclusive proof that nothing can be "really moving" and/or that you can never have good grounds for deciding which of two objects is moving, nor should they have. We have means of looking "outside" of our little moving system. Not in hundreds of years was the claim that "no one can ever tell who's really moving" taken as the "lesson" of the relativity principle. Al's new transformation equations, in themselves, did NOTHING to change the centuries old view of the matter.
In fact, Galileo's relativity principle was used for the exact opposite conclusion. Scientists began to accept that there were "good reasons" to assume that the earth was not motionless EVEN THOUGH we couldn't "feel" it moving or otherwise directly detect it.
You act as though SR "proved" the opposite. It didn't. Never claimed to (as a theory). For centuries it was assumed that the "laws of physics" were the same on all inertial systems, and no scientist (generally speaking) came to the conclusions that Mach was insisting upon--that all frames were "equally valid." For them, there were hundreds of (good) reasons to believe that the earth was NOT motionless and was in fact "really moving."
Why is it that you seem to think that SR came up with, or incorporates, some new insights about such questions?
This post is kinda following up on one that went into the spam bin that I hope you can retrive.
Up a little I quoted from a wiki article on time dilation which said: ""As there is no such thing as absolute motion in relativity (as is also the case for Newtonian mechanics), both the green and the red fleet are entitled to consider themselves motionless in their own frame of reference."
Newton relied on no absolute frame and everyone has known since the time of Galileo that the laws of physics are the same in all inertial frames, and are "equally valid" for that purpose. This was not a sudden revelation that the world of physics encountered for the first time in 1905. Almost 400 years earlier Galileo had shown that only relative velocities are measurable, not absolute velocities.
Physics has often been described as the study of "matter and (or in) motion." How could there be any study of "motion" if no one can tell what it is when they see it? All physical scientists, including, but certainly not limited to, physicists take the "reality" of motion for granted, as people and as professionals.
So why is it that only in relativity do you get, repeatedly, statements of "fact" from guys like our physicist friend who flatly tell you "you can never know who's moving" (with reference to a video which demonstrates the opposite). Why do people think THAT is part of SR? It isn't, it's simply the philosophical claims advanced by relationalists who have "taken over" SR, kinda like the Marxists took over Russia. The claims of relativists in that respect are totally contrary to what every other ordinary scientist believes and acts upon every day.
A professor of biochemistry doesn't constantly caution himself and his students that they can't know if the microbe they are seeing through a scope is really moving because it could be that the whole earth is moving while the microbe remains motionless. Engineering professors don't constantly warn their student that they can never know if levers, cranes, trains, and planes really move. Why not?
Ever ask yourself those kinda questions, Eric? They do have answers, I believe.
The attempt to impose standards, all while denying there are any standards, and the attempt to present a "theory of motion," all while claiming that the motion of individual objects is undetectable and unknown, is not a winning proposition. The hypocrisies, double standards, inconsistencies, and incoherencies always surface, and are readily seen by all except the devoted faithful.
There are historical reasons why Al came up with SR that I've presented in this thread (even though it seems quite apparent that you have little interest in historical or philosophical considerations).
In a nutshell, here it is: Maxwell's equations came up with formula which included the "speed of light," but the formula did not say what the speed was relative to (was it it's source? the earth? the fixed stars? the surrounding atmosphere? the ether? What?). Most scientists at the time assumed it was relative to the "motionless" ether. If that were the case, then the relativity principle would still apply in all inertial frames. In that case the speed of light would not be constant in all frames, but each such frame would still base its "physics" on the one and the same unvarying referrent--the ether.
When that didn't pan out, Al, who was obsessed with uniformity in physics, came up with an ingenious scheme. Why not just say the speed is relative to YOU (whoever you are, wherever you are--so long as it's an inertial frame--and whatever speed YOU'RE going!? Yeah, that's the ticket. All physics will be relative to YOU.
Sounds good, but it really doesn't work out except in the most superficial way. To begin with, you have to explain "why" each person sees the speed of light the same. No real problem there, Lorentz had already figured out the equations, and it's because each person's rods contracts and clocks get retarded with speed. And as it turns out, this (or some close variation of it) does seem to be the factual case.
Continued in next post
But, even so, you now have to try to base objective physics on subjective individual perception. That's it's own independent problem, which I will come back to. And it doesn't help that you've already posited that their "perceptions" are based on deformed measuring instruments. In that case, all you are really saying is that their "perceptions" cannot be uniform (except to themselves), so where's the uniformity in physics? How can you say physics and its laws are "uniform" when you must change your standards for lenghth and distance for every one of an infinite number of varying speeds?
Worse yet, all individual perceptions (deformed measuring instruments aside) are inherently dependent upon perspective, which varies from person to person. Furthermore, how one "perceives" things (i.e., what conclusions he draws about the meaning and import of his sense impressions) is further dependent upon the assumptions he makes. If someone makes the "wrong" assumptions (e.g., if he doesn't assume he is motionless with respect to all things moving relative to him) then the whole purpose is defeated--the relativity principle is nor longer valid for HIM (as Al said it must be).
The very attempt to makes the laws of physics relative to YOU, the subjective individual, is counter to the very foundations of physics, which relies on impersonal matter and forces, not subjective perceptions, to explain external reality.
In an attempt to make these flaws appear to be acceptable, it first became apparent that a dictatorial way of MAKING people adopt the assumptions about their state of motion that you wanted them to adopt had to be developed. One such tactic, adopted early and used often, was developed as a response to "stupid" people who might ask "but what if I'm the one moving?" The tactic was to treat the with derision and scorn, suggesting that their question was utterly, naive, stupid, and meaningless by shouting at them "NOBODY CAN TELL WHO'S REALLY MOVING! That's what the relativity principle dictates. Your question is stupid."
Of course the relativity principle says no such thing. And that is just one of many "tactics" used to enforce heterodox views about one's own motion. Likewise, if a person asked why an admittedly deformed yardstick should be used as a standard for comparison with undeformed rods, he would be told that "A YARD IS WHAT A YARDSTICK MEASURES, NO MORE, AND NO LESS. IF YOUR YARDSTICK SAYS IT IS A YARD, THEN IT *IS* A YARD."
It goes on and on. As much as SR advocates shout that their pet philosophical presumptions have been "tested and confirmed numerous times" (they haven't), insist that there are no contradictions between insisting that all frames are reciprocal when the theory predicts otherwise, and generally proclaims themselves indisputably victorious in their philosophical battles, the inherent problems still don't go away for some reason. Go figure, eh?
The "next post" has apparently been dumped in the spam box, eh?
A five foot square table top does not simultaneously contort itself into 100 different shapes so that 100 different observers in the room can all see it "just as it really is." Neither perceptions or objective reality work that way, I'm afraid.
Likewise, two planets a given distance apart, do not simultaneosly move nearer to, and farther from, each other so that 1 million observers who perceive the distance between them differently can all see the distance "just as it really is." This problem doesn't disappear if one wants to says that rods don't contract, but space does.
It's all logically impossible. One distance cannot simultaneously be 1 million different distances. Of course the gullible subjectist will always ask "why not?"
Back to Newton for a minute. Newton never claimed that the motion of objects could or should be gauged with respect to some "absolute" motionless point. He fact he disclaimed such a possibility.
What he did say was that, with respect to the solar system and the objects in it, the center of mass of the system was motionless with respect to those material bodies (even if the whole system was flying through space at some unknown speed). The sun itself orbits that spot. So do all the planets, meteors, astroids, and other material bodies which belong to the "system."
That point (the center of mass) could therefore reasonably and consistently be used as a reference point for the relative motions and velocities of the objects in the solar system. Nothing "absolute" about it. Nothing mystical, metaphysical, or unreasonable about it. Relavtists trumpetting Al's destruction of Newton's "abolute space" don't really even understand what they're talking about.
aintnuthin said...
... they are not tangible "things." Rods and clock are said to "measure" distance and time, and they do, imperfectly or not. But the measurements are not distance or time, per se, and "measuring" time and distance does not make them any less abstract as concepts.
Maybe this is just vocabularly, but it seems to me you can't measure a concept. I agree they are not tangible. I disagree that makes them concepts. I see them as real, external, and not tangible.
For me the phrase "abstract concept" is really just a redundancy. There are no "concrete concepts" and concepts exist only as an abstraction.
I would see "abstract" and "concrete" as referring to a person's real experience with a concept. An IT worker has a very concrete concept of a computer, an impoverished desert nomad has an abstract concept of one. But that's a tangent.
Time does not have a "coporeal existence," although clocks do. But that doesn't make time a physical thing, ...
"Corporeal" was a bad choice of word. But if time had no physical existence at all, it would not effect physical things.
I trying to plumb your intended meaning, not mine. What did you mean by "really moving" when you denied that it was part of "mainstream SR?"
The notion that inertial motion is a property of an object unto itself, as opposed to an object as a part of a system of objects.
And what did you mean by saying it's "not a part of?"
SR makes no use of it. It only uses the inertial motion of an abject as a part of a system of objects.
1. Did you mean SR does not purport to be Webster's and undertake to define common words, like "moving" and "real," or
No.
2. Did you mean that SR rejects the notion that things can be "really moving?"
No.
But are you trying to say that motion is irrelevant to which one ages more slowly?
I am saying that the notion the unaccelerated twin is at rest is irrelevant to which one ages more slowly.
What does this mean?
If both of the twins are initally moving together (by whichever method you determine something is moving), and one twin stops moving (according ot that determination), and then catches up to his unaccelerated twin, the accerated twin still ages less.
What does "pulled up to a stop" mean? Does that mean he achieved a state of absolute motionlessness?
By whichever method you decide a state is motionless, yes.
From what frame of reference would he be seen to "stop?"
For whichever inertial state is your method decides is motionless.
Wrong. Ontology aside, SR, as a theory, requires that if there are two relatively moving observers, each must AT THE SAME TIME, assume the other is moving.
You just said "Ontology aside", and then made a statement with deep roots in an ontological determination of the system. Neither observer has to assume the other is wrong, becasue they are examining valid claims, not ontological proclamations.
Here's an apparent inconsistency from Hogg in this very example. He says: "In addition to agreeing on the number of ticks, Dand E also agree on their relative speed."
How can they agree on their relative speed if D always sees the distance separating him from E to be less?
In mainstream SR, D does not see a different distance separating him and E than E sees of D.
What's he's saying does seem to make inherent sense, though. How could a traveller see light hitting his mirrors 100 times and we on earth see the light hitting his mirrors 200 times? We couldn't, not if we're looking at the same clock.
We could see our own light clocks ticking 200 times, and I left consideration of that possibility out of my post. Hogg does not explicitly say that we wouldn't, but it's implied. Why? Well...
1. In that case, you can't explain the "time dilation" by virtue of the length contraction, as he does here.
I'm not sure what you mean here.
2. Then would D also see our clocks stike it's mirrors 200 times? If so, then where's the reciprocity?
D would see our clock strike its mirrors 50 times. One way to think it is that the other 150 times D has not seen are still in transit from D to E.
In that case:
A. We see our clock making 200 ticks, and his only 100, so his clock is slow, but...
B. He sees our clock making 200 ticks, but his only 100, so our clock is fast to him, not slow
B would be the prediction of the version of LET you have been promoting. Note the difference between what I said above (D would observe 50 ticks) and yours.
How is (1) "the twin in the space ship aged less" the "same [answer] regardless of the assumptions you make" as (2) "the twin in the space ship ages MORE?"
(1) and (2) are not the same, but (2) is not a prediction of mainstream SR. In mainstream SR, the only time you can effectively and unbiasedly compare the twins ages is after they have been rejoined. At that time, the accelerated twin will have always aged less. (2) never occurs after the twins have been rejoined.
I said: "Show me one person who ever claims to have "seen" time moving slower in another inertial frame. That is not the claim."
You responded? "That is a claim of mainstream SR."
It is? Who do they claim has "seen" it?
Experiments on muon decay show a greatly extended half-life when the muons are traveling near light-speed. It not a direct as clock observation, I agree.
The question for SR is, how can the twin "see" earth clock running slow when, in fact, HIS clock is running slow?
How can he not see it? While they are in different inertial states, there is no one controlling state.
You act as though SR "proved" the opposite. It didn't.
Your misunderstanding of me here has persisted for several pages of comments.
Why is it that you seem to think that SR came up with, or incorporates, some new insights about such questions?
I don't know why I seem to think that way, because I don't think that way with regard to the validity of relative frames of motion. You'll have to answer the "seem" part yourself, because I don't "seem" to be anything such thing to myself.
So why is it that only in relativity do you get, repeatedly, statements of "fact" from guys like our physicist friend who flatly tell you "you can never know who's moving" (with reference to a video which demonstrates the opposite).
You've just been defending the notion that, uses the assumptions that relativity uses, you can't know who is really in motion, and that you need to use other methods to make such a determination. Why askl a question you just answered? Is your real complaint that relativity theory needs to expanded to include all concepts from physics, instead of the concepts it curretly incorporates? Why is it wrong to just look at the effects of a subset of the principles of physics? If that flatly contradict other aspects of physics, then physics is wrong as a formal structure. If not, you get a decent idea of which aspects of reality are responsible for certain effects. How is such knowledge wrong to have?
Ever ask yourself those kinda questions, Eric? They do have answers, I believe.
You have asked me such questions, and I answered them quite a while ago. There is little change in the questions this time around. People incorporate the principles of physics they need to get teh answers they need at the time.
There are historical reasons why Al came up with SR that I've presented in this thread (even though it seems quite apparent that you have little interest in historical or philosophical considerations).
I read every word. There isn't much to say about it.
But, even so, you now have to try to base objective physics on subjective individual perception.
Again, you confuse "subjective, individual perception" with "objective, situational observation".
In that case, all you are really saying is that their "perceptions" cannot be uniform (except to themselves), so where's the uniformity in physics?
Isotropy and homogeneity, which are both preserved under SR.
How can you say physics and its laws are "uniform" when you must change your standards for lenghth and distance for every one of an infinite number of varying speeds?
You don't change your standards. You keep your standards the same. You use the same meter sitck, light wavelength or whatever to define distance. You use the same clock, or elcetron orbut count, or whatever to define time.
If someone makes the "wrong" assumptions (e.g., if he doesn't assume he is motionless with respect to all things moving relative to him) then the whole purpose is defeated--the relativity principle is nor longer valid for HIM (as Al said it must be).
Again confuses the empirical (a valid claim) with the ontological (a statement of an overriding reality).
... by shouting at them ...
You must have had some really bad teachers.
A five foot square table top does not simultaneously contort itself into 100 different shapes so that 100 different observers in the room can all see it "just as it really is." Neither perceptions or objective reality work that way, I'm afraid.
Of course not. That's why I say rods don't actually contract and clocks don't acutally slow down.
On th eother hand, casting light from 100 different angles can allow for real effects deriving from the juxtaposition of the 100 different light to the same table. So, even though the table does not change, the different positioning of the lights with respect to the table is a real physical phenomenon (although not a corpoeal one) that can have real, coporeal effects.
It's all logically impossible. One distance cannot simultaneously be 1 million different distances.
But it can be meansured as 1 million different distances, each with an equally valid claim to being correct.
Unlike Newton, who never attempted to offer an absolute velocity, relative to a point completely at rest with respect to every other thing in the universe, Al did just that. He tells you that in that frame of reference (necessarily an inertial one) the speed of light is 186,000 mps. So now we know, eh? According to Al, the speed of light in Maxwell's equations is relative to a motionless "ether."
One Brow said: "D would see our clock strike its mirrors 50 times. One way to think it is that the other 150 times D has not seen are still in transit from D to E."
Why would anybody think about it that way? The guy is going from planet A to planet B. The light from each and every tick will eventually reach earth, and they can ALL be counted.
One Brow said: "Note the difference between what I said above (D would observe 50 ticks) and yours." I certainly note the difference from what you said and what Hogg (not me) said. Professor Hogg seems very sure of himself on this point. Later he uses this very scenario to illustrate what a "scalar" is.
"A scalar is a quantity that is the same in all reference frames, or for all observers. It is an invariant number...In Chapter 2, the number of ticks of D's clock in going from planet A to planet B is a scalar because although observers disagree on how far apart the ticks are in time, they agree on the total number."
Maybe you should inform him that he just doesn't understand "mainstream SR" (which I interpret to mean whatever claim you care to make on a blog), eh? How ya figure he done went and gone all kinda wayward, eh?
Your scenario makes so sense at all. We both see the ticks on his clock to total 100, but on OUR clock, he sees 50 and we see 200? Heh.
One Brow said: "In mainstream SR, D does not see a different distance separating him and E than E sees of D."
Maybe you best tell wiki they don't understand "mainstream SR" either, eh?
wiki: "SPECIFIC EXAMPLE: Consider a space ship traveling from Earth to the nearest star system outside of our solar system: a distance d = 4.45 light years away...In [the ship's] rest frame the distance between the Earth and the star system is εd = 0.5d = 2.23 light years (length contraction), for both the outward and return journeys."
So, the distance between the earth and the star is cut it half on both legs of the journey, but they always see the distance between the two as 4.45 light years, just the way earthlings see it? How does that work, exactly?
One Brow said: "In mainstream SR, the only time you can effectively and unbiasedly compare the twins ages is after they have been rejoined."
What, the Lorentz transformation equations, upon which SR is totally based and dependent, is now a "bias?" The equations tell you who is aging slower and at what rate WHILE THEY ARE MOVING, not when they are at rest. The equations do not say they only hold true if the moving party returns.
I think I now understand what "mainstream SR" really is. It appears to be the doctrinal handbook passed out by relationalists telling their disciples how to rewrite SR to make it compatible with their claims.
I said: "The question for SR is, how can the twin "see" earth clock running slow when, in fact, HIS clock is running slow?"
You responded: How can he not see it? While they are in different inertial states, there is no one controlling state.
What does "one controlling state" have to do with anything? One clock (the satellite one) reads 5:00, and the other (the earth clock reads 5:05) per Keating, et al. Are we supposed to be looking at clock's or some unspecified and irrelevant notion that you have about "controlling states." Keating and them just look at the clocks, best I can tell.
One Brow said: "Is your real complaint that relativity theory needs to expanded to include all concepts from physics, instead of the concepts it curretly incorporates? Why is it wrong to just look at the effects of a subset of the principles of physics? If that flatly contradict other aspects of physics, then physics is wrong as a formal structure."
The point is that this claim is NOT a part of the physical theory of SR. It simply a continuation an age-old philosophical dispute, such as Liebniz picked with Newton. A minutely small minority (Liebniz, Berkeley, Mach, and a few others)have tried to invalidate physics on philosophical grounds and that faction infiltrated SR with a vengence. It had nothing to do with physics, and physicists who took (or take) an interest in it do so because are interested in philosophy, not physics.
The principle of relativity NEVER said you can't tell who's moving. All inertial frames of reference are "equally valid" for the purpose of applying physical laws, but that does not mean no one could tell that Gallileo's moving ship was moving across the sea.
The claim that the "relativity principle" tells you that all motion is indiscernable is simply false, and no one but philosophical fanatics believes it or subscribes to it
One Brow said: "Of course not. That's why I say rods don't actually contract and clocks don't acutally slow down."
You're obviously welcome to "hold" whatever view you choose, but don't impute it to SR. SR says they do. If they don't, then that reverses SR's presumption about the matter and reverses all of it's conclusions. Maybe you should develop some anti-lorentz equations and get us back to where Al started, eh? To once again quote Hogg:
"A common confusion for students of special relativity is between that which is real and that which is apparent. For instance,length contraction is often mistakenly thought to be some optical illusion. But moving things do not "appear" shortened, they actually are shortened."
"actually are shortened," get it?
One Brow said: "You don't change your standards. You keep your standards the same. You use the same meter sitck, light wavelength or whatever to define distance. You use the same clock, or elcetron orbut count, or whatever to define time.'
Heh, you make a claim like this, and then try to pretend you're not a Machian logical positivist? Did you even read the source I referred to where Al rebutted this claim when advanced by a logical positivist? Of course the positivist imputed the claim to Al (as they always do--i.e., they always claim Al agrees with their absurd philosophical premises), which pissed him off.
One Brow said: "But it can be meansured as 1 million different distances, each with an equally valid claim to being correct."
Anybody, and I mean ANYBODY, who insists that a train passenger has an "equally valid" claim to being at rest while the earth rushes past him, as people sitting on benches at the station as he pulls out having to claiming he's moving, doesn't have a lick of common sense. Talk about "brain in a vat" philosophy, eh?
One Brow said: "Wrong. Ontology aside, SR, as a theory, requires that if there are two relatively moving observers, each must AT THE SAME TIME, assume the other is moving.
You just said "Ontology aside", and then made a statement with deep roots in an ontological determination of the system. Neither observer has to assume the other is wrong, becasue they are examining valid claims, not ontological proclamations.
You keep using the word "ontological" as if you understand how and when it applies, but you don't.
If I say 2+2 = 4 and 2+3 does not equal 4, I am NOT making an ontological statement. I am describing the a priori implications of the postulates of a formal mathematical system.
Likewise, if I say that the relativity principle, as AL describes it, will NOT hold true if both parties agree on which of them is moving, I'm not saying anything ontologically different than I am when I say 2+3 does not equal 4.
aintnuthin said...
Why would anybody think about it that way? The guy is going from planet A to planet B. The light from each and every tick will eventually reach earth, and they can ALL be counted.
I think there was some confusion here. We, as E, see D's clock tick 100 times whiles ours ticks 200 times. In teh time D sees his clock tick 100 times, he sees our clock tick 50 times. The reson for this difference is the transit time of light between the destinations.
Let's add something to illustrate. Lets say the color in D's clock changes from green to blue after the 100 ticks. Then, when the blue light reaches our clock, our clock's light will change from red to orange. We and D both see Ds clock change after the 100 ticks. However, what D also sees is our clock having made 50 ticks before his light changes, and then our clock making another 150 ticks before our clock's color changes. We see our clock and Ds clock changing color at thesame time, D sees them as greatly separated occurences.
Your scenario makes so sense at all. We both see the ticks on his clock to total 100, but on OUR clock, he sees 50 and we see 200? Heh.
Light does not travel instantaneously.
One Brow said: "In mainstream SR, D does not see a different distance separating him and E than E sees of D."
Maybe you best tell wiki they don't understand "mainstream SR" either, eh?
My error, I should have said speed, not distance. They always see each other with the same relative speed.
One Brow said: "In mainstream SR, the only time you can effectively and unbiasedly compare the twins ages is after they have been rejoined."
What, the Lorentz transformation equations, upon which SR is totally based and dependent, is now a "bias?"
The Lorentz equations allow you transform one coordinate system into another coordinate system. They do not establish any particular coordinate system as unbiased. No mere equation can do that. Equations don't dictate reality. Stop being a logical positivist.
The equations tell you who is aging slower and at what rate WHILE THEY ARE MOVING, not when they are at rest.
They also work for objects that are at rest.
What does "one controlling state" have to do with anything? One clock (the satellite one) reads 5:00, and the other (the earth clock reads 5:05) per Keating, et al.
You are confusing net change with instataneous change.
The point is that this claim is NOT a part of the physical theory of SR.
SR is a thoery of the knowledge you can derive based on specific principles. Those principles insist that any inertial state can be validly treated as a rest state. As you pointed out, this has been know since Galileo (unless you are about to retract several paragraphs of your history). So, according to you, this claim is not only a part of SR, but goes back to Galileo. Your association of it with a specific minority of philosophers is simply wrong.
All inertial frames of reference are "equally valid" for the purpose of applying physical laws,
You just acknowledged mainstream SR. Finally.
but that does not mean no one could tell that Gallileo's moving ship was moving across the sea.
Which has what to do with the price of tea in China?
The claim that the "relativity principle" tells you that all motion is indiscernable is simply false,
As well as not being a claim of mainstream SR.
You're obviously welcome to "hold" whatever view you choose, but don't impute it to SR. SR says they do.
LET says they do. SR says the contraction is a feature of the system in which they are location, not a feature of the rods/clocks themselves.
"actually are shortened," get it?
Yes. You're the one who's missing it. They actually are shortened, but not because of some change to the physical rods and clocks.
Let's play a game. Why don't you quote 100 different physicists who say the shortening is real, and see at some point I deny it is real. Who knows, maybe one day I'll be flu-ridden and so feverish that I'm delusional, and actually deny the shortening is real. Until then, all your accomplishing is to miss the point. I agree the shortening is real. Quoting that it's real won't change that.
One Brow said: "You don't change your standards. You keep your standards the same. You use the same meter sitck, light wavelength or whatever to define distance. You use the same clock, or elcetron orbut count, or whatever to define time.'
Heh, you make a claim like this, and then try to pretend you're not a Machian logical positivist?
Yes, it was careless. I should have said "define units of distance" and "define units of time". Other than that, my statement stands.
Anybody, and I mean ANYBODY, who insists that a train passenger has an "equally valid" claim to being at rest while the earth rushes past him, as people sitting on benches at the station as he pulls out having to claiming he's moving, doesn't have a lick of common sense.
Anyone who disagrees doesn't understand what valid means.
If I say 2+2 = 4 and 2+3 does not equal 4, I am NOT making an ontological statement. I am describing the a priori implications of the postulates of a formal mathematical system.
I agree. How was that supposed to correct my understanding of ontology?
Likewise, if I say that the relativity principle, as AL describes it, will NOT hold true if both parties agree on which of them is moving,
Then you're just wrong. What people agree or disagree upon does not change physical reality. I'm not surprised to see your inner subjectivist shine through, though.
I didn't see anything that addressed my comments about the deep ontological roots of your statements, much less corrected them.
One Brow said: "You must have had some really bad teachers."
Ya know, Eric, when I first came across SR in my early teens, I was fascinated by it. I felt I had just been introduced to some mysterious secrets about the universe. It all sounded so natural and logical at the time. I read several books on it to try to get a fuller understanding. After a while, I got the nagging feeling that something just wasn't consistent in all the seemingly impeccable explantions I was reading, but couldn't quite put my finger on what it was.
The more I read about it, and closely analyzed what I read, the more convinced I became that the explanations I was reading were highly selective in what they said and didn't say, that they were rife with equivocation, and that they ultimely all just assumed, beforehand, the indisputable truth of their conclusions rather than in any way demonstrate really demonstrating them. Still, I couldn't quite put my finger on just what was going on.
When I later asked questions that the books never really seemed to answer (except by assertion), I soon found out. Certain thought patterns are simply not allowed to be uttered in SR. To even ask why a guy on a train would think he was motionless was NOT a proper topic of dicussion. They guys came across as "instructors" at commie "re-education" camps. The topic was open for discussion, it was to be swallowed hole, memorized, and regurgitated at test time, that's all. It wasn't a question of whether is was consistent...I mean the question of consistency could not be raised. Just memorize it, and "know" it--don't worry, we wise ones all know it's 100% true so you don't need to worry your pretty little head about that.
Now I see more clearly how self-deluded, unsophisicated, uncritical, and lacking in true analysis some of these muddled jack-asses, like our physicist friend, really are. They assert, they do not explain, and they assert non-sensical things thinking it must somehow make perfect sense (presumably because they believed their teachers when they were so assured).
[carried away again--post too long--continued in next post]
Al clearly said that if his postulates were true, then by necessary logical implication, observers in different frame MUST measure time and length differently. I understand that. I also understand that his postulates are just that (postulates, not "facts") and as such, they never have been and never will be empirically established or confirmed.
If teachers would just put it like that, they wouldn't have to browbeat students who asked questions they couldn't really give a good answer to. If they had just said: "Look, no one said it is right, I'm just teaching you what the theory implies, right or wrong, and everything I'm telling you simply assumes it's premises to be true, even if they are 100% wrong. These circular explanations I'm giving you are simply a result of that--I am assuming that the premises are correct, in fact, the conclusion are my premises. That's how these kinds of "explanations" work. You CANNOT EVER question the validity of the postulates within the context of a theory, even if they produce ludicrous conclusions"--or something along those lines, I would have said "OK."
But they didn't. Like our jackass physicist friend, they felt obligated to assure you that everything they were telling you was indisputable empirical fact proven to be so by numerous experiments. They had to pretend that they personally knew exactly how things are and were simply trying their best to beat, I mean instill, the truth in their ignorant students. Not a good stance to take when you really don't even know what you're talking about.
They all had what seemed like a million "canned answers," none of which were "answers" at all, but rather assertions which evaded, not addressed, questions. Such as "it makes no sense to even think about which one is moving because YOU CAN NEVER TELL WHO'S MOVING."
Of course then you wonder why they are constantly talking about one observer moving and another not. Why do they even talk about absolutely unknowable things, and pretend they know what they're talking about?
One Brow said: "As you pointed out, this has been know since Galileo (unless you are about to retract several paragraphs of your history). So, according to you, this claim is not only a part of SR, but goes back to Galileo."
Please...as I said, Galileo noted that WITHIN A COMPLETELY CLOSED SYSTEM you cannot determine that you are moving. He immediately followed this with the acknowledge that if you were on deck, watching the shore go by, you would know you were moving.
To reiterate, the relativity principles does not now, nor did it ever, in and of itself, imply that you can never tell if you or anyone else is moving. These relativists want to take a very carefully restricted statement and pretend that it is univerally true under any and all circumstances. That is simply a philosophical add-on, courtesy of Berkeley.
One Brow said: "You are confusing net change with instataneous change."
What is this supposed to mean? I asked you before: Are you suggesting, that until such time as the plane clock landed, it read 5:05 while the earth clock read 5:00, but when it landed, it quickly changed it's reading to 5:00 while the earth clock, hearing the plane land, quickly reversed itself to read 5:05?
If you're not trying to say something like that, I have no clue what you're talking about.
One Brow said: "The reson for this difference is the transit time of light between the destinations."
No, Eric, transit times, which can always be corrected for, do not, and cannot explain your claim. A clock a millions miles away (a few seconds in light time) will be "seen" to run at the same rate our clocks do if it shares our inertial frame. How could WE see his clock make 100 ticks, and HIM also see his clock make 100 ticks, under your mistaken scenario to begin with, if what you're saying is right?
What you are saying that we both see his clock the same (100 ticks) but we each see our clock, and ONLY our clock, to tick differently? Where's the reciprocity of frames? Is there a time delay in light going one way only?
This is just the kind of "reasoning" and "explantion" SR advocates always seemingly resort to.
Put another way: Hogg claims the number of ticks is a scalar, invariant in all frames and completely frame independent. Is the number of ticks a scalar ONLY if we are both looking at his clock, but not if we are both looking at our clock, ya figure?
One Brow said: "They actually are shortened, but not because of some change to the physical rods and clocks."
Eric: "That's why I say rods don't actually contract and clocks don't acutally slow down."
Hogg:"... moving things do not "appear" shortened, they actually are shortened."
He explictly says they are "actually shortened" you explicitly say the are NOT actually shortened, yet of course, as always, all experts agree with YOU.
Eric you can misunderstand and misapply words and concepts like "physical changes" "real" versus apparent, all you want and apparently easily convince yourself with your equivocal word play. But don't expect others to be fooled as easily as you fool yourself.
If there is no real physical change, then the change is "only apparent," which Hogg clearly denies. For you a shadow is to be treated a real, tangible, three-dimensional object, which demonstrates how unrefined your ability to draw critical distinctions really is.
You want to talk about "casting light" on table tops to create strictly perceptual effects and treat them as being a "real, physical change" to the table top itself. It aint, sorry.
One Brow said: "Then you're just wrong. What people agree or disagree upon does not change physical reality. I'm not surprised to see your inner subjectivist shine through, though."
Al formulation of the relativity principle is NOT "physical reality," sorry. It is a physical theory. It claims that all people in inertial frames will perceive the speed of light to be 186,000 mps. A passenger on a train will NOT so percieve the speed of light if he assumes that he is moving, not the earth. Al's assertion about the perceived constancy of the speed of light in all frames fails at that point. It has nothing to do with "physical reality." His theory is not based on physical reality insofar as it talks about what every subjective observer will conclude about the universality of the "laws of physics."
One Brow said: "I didn't see anything that addressed my comments about the deep ontological roots of your statements, much less corrected them."
Nor, apparently, will you ever see anything that doesn't already comport with your existing assumptions, reach your conclusions, define things in the same idiosyncratic way you do, etc. Anything that doesn't presume that your pre-existing conclusions are right is incomprehensible to you. You wouldn't "see" a correction if it pistol-whipped you half to death.
aintnuthin said...
Certain thought patterns are simply not allowed to be uttered in SR. To even ask why a guy on a train would think he was motionless was NOT a proper topic of dicussion.
Well, I can see that. Relativity theory doesn't care whether the guy thinks he is motionless or not.
Al clearly said that if his postulates were true, then by necessary logical implication, observers in different frame MUST measure time and length differently. I understand that. I also understand that his postulates are just that (postulates, not "facts") and as such, they never have been and never will be empirically established or confirmed.
You mean, it hasn't been established nor confirmed that the speed of light has always been measured at c? What other speed has it been measured at? Or, do you mean it hasn't been established or confirmed that identical experiemnts in inertails states gives identical results? Are you referring to common scientific assumptions like isotropy and homogeneity? I'm not aware of any other assumption needed by mainstream SR.
They all had what seemed like a million "canned answers," none of which were "answers" at all, but rather assertions which evaded, not addressed, questions. Such as "it makes no sense to even think about which one is moving because YOU CAN NEVER TELL WHO'S MOVING."
So, you think you can tell who's moving from the results of experiements conducted within a system? Galileo was wrong?
Please...as I said, Galileo noted that WITHIN A COMPLETELY CLOSED SYSTEM you cannot determine that you are moving.
Yes, this is the assumption used for mainstream SR. No further assumption about reciprocity is needed, except for the constancy of light. If you agree with it, then mainstream SR is no more relational than you are.
He immediately followed this with the acknowledge that if you were on deck, watching the shore go by, you would know you were moving.
Mainstream SR ignores that. It does not reject it, nor accept it. It just ignores it.
What is this supposed to mean? I asked you before: Are you suggesting, that until such time as the plane clock landed, it read 5:05 while the earth clock read 5:00, but when it landed, it quickly changed it's reading to 5:00 while the earth clock, hearing the plane land, quickly reversed itself to read 5:05?
No. I am saying that the difference between what you are proposing and mainstream SR is not the total mount of time the clock will read, but how fast the pico-seconds are ticking at that given moment in time where it passed overhead.
No, Eric, transit times, which can always be corrected for, do not, and cannot explain your claim. A clock a millions miles away (a few seconds in light time) will be "seen" to run at the same rate our clocks do if it shares our inertial frame.
I agree. But D and E do not share an inertial frame.
How could WE see his clock make 100 ticks, and HIM also see his clock make 100 ticks, under your mistaken scenario to begin with, if what you're saying is right?
What forces us to stop counting ticks? In moving from point A to point B, the clock ticks a specifc number of times. I don't understand your question.
What you are saying that we both see his clock the same (100 ticks) but we each see our clock, and ONLY our clock, to tick differently?
Both E and D see that their respective clocks tick differently from each other, but that doesn't seem to be what you asked. Differently from what?
Where's the reciprocity of frames? Is there a time delay in light going one way only?
No, it works both ways.
This is just the kind of "reasoning" and "explantion" SR advocates always seemingly resort to.
Did you understand the light-changing-color scenario I described? Do you have a specific objection to why things wouldnot work that way?
One Brow said: "You are confusing net change with instataneous change."
Eric, as you may have heard (if not look it up), they have developed extremely sensitive and accurate atomic clocks these days. Set two of them on a desktop next to each other, and hour after hour, day after day, they will agree with each other.
But raise one by a foot and you will instantly see the rates of the two clocks change (due to gravitational time dilation). You can look at them simultaneously, they're only a foot apart. Same with speed. These clocks are so sensitive that they reflect dilation due to motion at very low speeds, like walking across a room with one. Same thing: The moving one reads slower. The guy carrying the moving clock can see the same changes that a guy staying in his chair does. They both see the moving clock running slower and the stationary clock running faster, even though one guy is moving right along with the moving clock and one guy isn't. How could they possibly see digital readouts differently to begin with?
Put another way: Hogg claims the number of ticks is a scalar, invariant in all frames and completely frame independent. Is the number of ticks a scalar ONLY if we are both looking at his clock, but not if we are both looking at our clock, ya figure?
D's clock is the that is actually mooving between the points we are using as a frame of reference. E's clock is nowhere near those points. So yes, only D's clock appears to register 100 ticks to all observers, because only it has a negligible spacetime difference to point A and then Point B.
He explictly says they are "actually shortened" you explicitly say the are NOT actually shortened, yet of course, as always, all experts agree with YOU.
As you quoted, I say they are actually shorten, but not because of a physical change to the rods and clocks themselves. If you can find a quote from Hogg saying there is a change internal to the rods and clocks, I will acknowledge he disagrees with me. Right now, we are both saying there is a real change, that the rods are shorter and the clocks are slowed. I am adding the information that this is not due to an internal change to the rods or clocks, while Hogg has not added that information nor added anything that disagrees with it.
But don't expect others to be fooled as easily as you fool yourself.
I'm not trying to fool you. However, you are fooling yourself.
If there is no real physical change,
Moot. There is a real physical change. but not onw internal to the rods and clocks.
For you a shadow is to be treated a real, tangible, three-dimensional object, ...
We both agree that some effects of shadows are real, tangible, and three-dimensional, even if the shadow is not.
You want to talk about "casting light" on table tops to create strictly perceptual effects and treat them as being a "real, physical change" to the table top itself. It aint, sorry.
I agree, it isn't a change to the table top/rod/clock. That's my point.
A passenger on a train will NOT so percieve the speed of light if he assumes that he is moving, not the earth.
What about that assumption changes his measurement? If you have two people on a moving train, and both lay out 10 yards using a yardstick, both time the two-way speed of light over those 20 yards, will they get different amounts of time if one assumes he is moving and the other assumes he is stationary? How do their thoughts affect the amount of time their clocks show? just what type of subjectivity are you pushing for here?
Nor, apparently, will you ever see anything that doesn't already comport with your existing assumptions, reach your conclusions, define things in the same idiosyncratic way you do, etc.
I didn't set the scope of relativity theory, and I'm not the one demanding it incorpoarte concpets like who is really moving. That would be your ontological insertion.
Anything that doesn't presume that your pre-existing conclusions are right is incomprehensible to you. You wouldn't "see" a correction if it pistol-whipped you half to death.
Is it jsut a little possible that there might be an ontological aspect to saying "who is really moving" that you had not considered?
These clocks are so sensitive that they reflect dilation due to motion at very low speeds, like walking across a room with one. Same thing: The moving one reads slower. The guy carrying the moving clock can see the same changes that a guy staying in his chair does. They both see the moving clock running slower and the stationary clock running faster,
Link?
even though one guy is moving right along with the moving clock and one guy isn't. How could they possibly see digital readouts differently to begin with?
Differently than what? Each other? How can they not, with lightspeed delay being a factor?
I said: I also understand that his postulates are just that (postulates, not "facts") and as such, they never have been and never will be empirically established or confirmed.
You asked: "You mean, it hasn't been established nor confirmed that the speed of light has always been measured at c?"
Of course not, I meant what I said. You could measure the round-trip speed of light to always measure c a million times a day for a million years, and that would not prove the theory's postulates, at least insofar as the "theorems" are concerned. LR predicts the same thing, based on different postulates.
I must make the distinction between "theorems" and postulates here because, I agree with the author's analysis who concluded that, from a mathematical perspective, LR and SR are identical theories.
Al "postulated" a way of determining which distant events are "simultaneous" based upon a definition which made assumptions about the behavior of light. This "definition was purportedly structured so that it could "tested," but actually ended up serving as a a priori stipulation in the nature of a postulate. As we have seen, it never was tested by Al, and would have, by his own terms, failed his test had it been.
The fact that the earth has been confirmed to resolve around the sun every 365 days or so does not prove the postulates of a geocentric theory of planetary motion, even though that outcome is predicted by it.
One Brow said: "D's clock is the that is actually mooving between the points we are using as a frame of reference. E's clock is nowhere near those points. So yes, only D's clock appears to register 100 ticks to all observers, because only it has a negligible spacetime difference to point A and then Point B."
I see you making an assertion here, but I see no intelligible explanation of the issue being addressed.
To see his clock we have to look across some amount of space. To see our clock, he must do the same.
We both see his clock to tick 100 times, even though he's sitting next to it and we are some distance away. But when he looks back at our clock, he sees only 50 ticks when we see 200? And this is because he is farther from us than we are from him, that the idea? What does his distance from the planets have to do with our clock when he looks at IT (not the planets) from a distance?
I know this all makes perfect sense to you, even if you just made it up on the spot. What is the general principle here that Hogg neglected to mention? Clock ticks are scalar only if you are on earth, looking at a distant clock, but clock ticks are NOT scalar if you are looking at an earth clock from the same distnce in space? That it?
One Brow said: "Mainstream SR ignores that. It does not reject it, nor accept it. It just ignores it."
Ignores, eh? Why would it ignore a crucial aspect of understanding the relativity principle, I wonder? Galileo did NOT say that if you were in a closed ship cabin, you would have no way of knowing whether a bug moving across the cabin floor was really moving with respect to the cabin or if the bug was actually motionless while the ship moved.
One reason he did not say it is because that would completely overthrow the principle of relativity and the related concept of inertial motion being unaltered in the absence of an external force. The bug could NOT stay motionless while the ship moved, because he would necessarily share in the ship's motion, with no ability to "detach himself" from it.
A bug on the cabin floor is no different than a train moving across the face of the earth. Yet our physicist friend tells us train passenger knows Mary misperceives the correct timing of the light flashes because she thinks she's motionless, while he knows beter because HE is the one who is motionless while she is moving and, guess what, HE IS CORRECT!
One Brow said: "What about that assumption changes his measurement? If you have two people on a moving train, and both lay out 10 yards using a yardstick, both time the two-way speed of light over those 20 yards, will they get different amounts of time if one assumes he is moving and the other assumes he is stationary? How do their thoughts affect the amount of time their clocks show? just what type of subjectivity are you pushing for here?"
It really doesn't take much thought to understand this Eric. Just read the physicist's explanation of why each one thinks the opposite about whether event A happened before event B. Analyze what he is saying, and why. Each knows how the other will (supposedly incorrectly) perceive the "true sequence," but why is that?
What would the guy on the train conclude about which event happened first if he assumed he was moving down the tracks? What conclusion would he arrive at about the speed of light, as perceived ("observed" in Hogg's nomenclature)from a moving train if he did that?
He would conclude that even though he "saw" the light from the front of the train first, it could not have actually occurred first if he assumes he is moving relative to the earth. Al, on the other hand, tries to dictate that his subjective and uncorrected perception of which happened first must reflect "reality" and SR accordingly forbids him from adopting the view that the train is moving. All the laws of physics are supposedly uniform because he is precluded from reflecting on, and adjusting, his raw and perspective-resultant perceptions.
It's like saying that if I see a super-nova "explode" in the sky now, I have to forever after insist that it happened at the very instant I became aware of it. I can't acknowledge that, even though I see it now, it had to have happened centuries ago.
The difference in the train passenger's assumptions about his own motion is basically the only difference in assumptions between SR and LR. As I said before, if the guy on the train acknowledges that it is him, not the earth, that is moving relative to the other, he has implicitly designated the earth to be the preferred frame. That CANNOT be allowed in SR. If that is done, the speed of light will be "observed" to vary from frame to frame, and NOT remain constant, once the deformed measurements are corrected.
Both SR and LR acknowledge that his measuring instruments are deformed, and that this creates the "appearance" of a constant speed of light. LR simply understands that raw appearances can be deceiving and permits considered adjustments to one's immediate sense impressions. It doesn't say that because a guy hears a thunderclap from 1 mile away before he heard one orginating two miles away, the one he heard first HAD TO HAVE actually happened first.
Upon even rudimentary reflection anyone could easily understand that when he heard them, standing alone, says virtually nothing about when they happened. Any cognizant person would have to conclude that any of the following 3 possibilities could be the actual (as opposed to the "apparent") case:
1. The one he heard first could have happened first (as Al's methods FORCE him to conclude while excluding the other two possibilities).
2. They could have happened at the same time, and one was farther away, or
3. They could well have happened at different times, and, for that matter, the one he heard second could have happened first.
It is easy to understand that the time at which he hears them, in itself, tells you nothing about the time they occurred. When he personally hears them is simply a function of his idiosyncratic and contingent perspective.
By the way Eric, just so you know, I don't see your new posts unless I make a post myself. Until that time they remain invisible. I usually kinda proof-read my own posts (after, but not before, I post them which is one reason I generally see plenty of typos, ommissions, etc.) But I don't always think to go back and scan for intervening posts which are not displayed.
As a result, I get started on a whole new train of thought before I ever end up responding to yours. But that's obviously not because I think those posts are responsive to yours--I didn't even see yours.
One Brow said: "Link?"
Plenty around, I'm sure. This one is from NPR:
Earlier this year, scientists built the most precise clock on Earth, an aluminum ion clock. These are among the most precise clocks ever built.
And now researchers have used a pair of these clocks to test Einstein's theory of relativity at a very, very tiny scale. They've been able to measure the miniscule changes in time that occur when you are sitting in a moving car or standing at the top of a staircase. The research appears this week in the journal Science.
Joining me now is Tom O'Brian, chief of the Time & Frequency Division I love that title - at the National Institute of Standards and Technology in Boulder, Colorado....
TOM: ...What happened in this experiment at NIST was that the scientists made a clock that is so accurate and so precise that instead of having to go at close to warp speed or something like that or be near a black hole, you can actually see the ticking, the change in the ticking rate of the clock just by lifting the clock up about a foot or by making the ion, which is the ticking part of the clock, just move at even walking or jogging speed."
http://www.npr.org/templates/story/story.php?storyId=130104039
I may not have remembered the facts exactly right, but I've read about this in various sources. Basically you see an instantaneous change in clock rate with even a slight increase in motion, right on the spot.
As far as light speed delay goes, that is easily correctable and must be corrected for proper "observation." Hogg put it as follows:
"in Chapter 2, when E measured the rate
of D's clock, she did not simply measure the time between light pulses she received, she corrected them for their light-travel times in getting from D's clock to her eyes."
Do you think Hogg is not aware of such effects, and provides answers based on a lack of such corrections? I don't.
Yet you said are arguing that one guy sees only 50 ticks while another sees 200 on the very same clock because, as I understand you, of light signal delay which is unaccounted for:
One Brow said: "In teh time D sees his clock tick 100 times, he sees our clock tick 50 times. The reson for this difference is the transit time of light between the destinations....D would see our clock strike its mirrors 50 times. One way to think it is that the other 150 times D has not seen are still in transit from D to E."
Why didn't Hogg say we both only see 100 ticks on his clock because of unaccounted for loss of signals from time delay and otherwise we would have seen 200? Instead he says the ticks are invariant to all observers.
That's why I said that the only natural implication would be that the space traveller would see 200 (not 50) ticks on our clock if that's how many times we saw our clock tick. Unless you assume a lack of reciprocity for a scalar effect, the will both see the same number of ticks in each others frames, even if the ticks they see are different. If our light hits our mirrors 200 times, that's the number he too would see if this is a scalar effect particularly, but even without that, based on the mere presumption of reciprocity of frames that is what you would expect him to see.
Light delay, eh? As I said before, typical of the kind of reasoning you typically get from an SR advocate. Consistency counts for nothing. Light delay doesn't occur on a one-way only basis, unless perhaps you think that assertion would help you "prove" your point.
I said: "It is easy to understand that the time at which he hears them, in itself, tells you nothing about the time they occurred. When he personally hears them is simply a function of his idiosyncratic and contingent perspective."
Show me the physicist that says the time of the physical event which leads to observers later hearing a thunderclap is NOT determined in accordance with the time at the place it happened, but rather only in accordance with when it is heard by various observers. Show me the physicist who claims, that, as a consequence, each thunderclap happens at hundreds or hundreds of thousands of different times, just depending on your frame of reference. Show me the one who says it impossible to say whose subjective perception could possibly be correct with regard to such questions. Lightning striking a cloud is what causes and leads to observers hearing "thunder" and physicists explain the phenomenon by reference to such objective external events, not by reference to the subjective perceptions of each observers. The observer hearing the sound in no way "causes' the sound---well, unless maybe you're a Berkeleyite, of course.
You've no doubt heard the old "philsophical" question: If tree falls in a forest and no one is around to hear it hit the ground, does it still make a sound?
Physicists would say sound waves are produced, whether anybody actually "hears" them or not. Others might say sounds waves are not sound, and that there is no such thing as a "sound" without an organ of auditory perception. Berkeley would say there can be no tree to fall in the first place if there is no subject there to to "create" it with his subjective perception to begin with.
To be is to be perceived. As soon as the observer looks away, the tree ceases to exist, and it never existed at all until he looked at it in the first place. Brain in a vat, I tellya! Of tremendous inspiration to, and influence upon, Hume, Mach, and the logical positivists, however.
One Brow said: "In mainstream SR, the only time you can effectively and unbiasedly compare the twins ages is after they have been rejoined."
I asked: "What, the Lorentz transformation equations, upon which SR is totally based and dependent, is now a "bias?"
You said: "The Lorentz equations allow you transform one coordinate system into another coordinate system. They do not establish any particular coordinate system as unbiased. No mere equation can do that. Equations don't dictate reality. Stop being a logical positivist."
You have it backwards, Eric, because you are playing to logical positivist here, not me.
The LT tells you (you don't have to believe it, of course, but either way it tells you) that the moving clock will always be slower, and the equations don't give a damn in you never in your entire lifetime ever figure out, even once, which one is moving. It will STILL be the moving clock which slows down, per SR, whether you ever know which one it is or not. The LT do not claim to apply ONLY IF you personally believe you know which one is moving. It is impervious to your state of knowledge in it's application. It is totally "unbiased," in that sense.
The logical positivists tend to want to equate what can be, and is, "true" with your subjective ability to know it. They confuse epistemology with physics. In effect, they try to suggest that O.J. Simpson can not possibly have either (1) killed his wife, or (2) not killed his wife unless YOU know for an empirical fact that he did or did not. There can be no "fact" of the matter if you, subjectively, don't know the facts. Other (normal) people would say: "Well, he either killed her or he didn't, as a matter of fact, but damned if I know which."
aintnuthin said...
Of course not, I meant what I said.
I listed both the postulates. You didn't specify which one was unconfirmed.
You could measure the round-trip speed of light to always measure c a million times a day for a million years, and that would not prove the theory's postulates, at least insofar as the "theorems" are concerned. LR predicts the same thing, based on different postulates.
Which postulate is different for LR?
Al "postulated" a way of determining which distant events are "simultaneous" based upon a definition which made assumptions about the behavior of light.
The only circumstance that allows you to determine whether events are truly simultaneous or not is when the events in question have a neglible distance between them. Your characterization here is wrong. I have no idea why you think this is a postulate of SR.
One Brow said: "D's clock is the that is actually mooving between the points we are using as a frame of reference. E's clock is nowhere near those points. So yes, only D's clock appears to register 100 ticks to all observers, because only it has a negligible spacetime difference to point A and then Point B."
I see you making an assertion here, but I see no intelligible explanation of the issue being addressed.
To see his clock we have to look across some amount of space. To see our clock, he must do the same.
We both see his clock to tick 100 times, even though he's sitting next to it and we are some distance away. But when he looks back at our clock, he sees only 50 ticks when we see 200? And this is because he is farther from us than we are from him, that the idea? What does his distance from the planets have to do with our clock when he looks at IT (not the planets) from a distance?
His distance from our clock causes his seeing fewer ticks than we see, not his distance from the planets. D's distance from the planets is what allows both of us to see the same 100 ticks of D's clock for the same events. But if it doesn't affect the number of ticks seen on E's clock.
I know this all makes perfect sense to you, even if you just made it up on the spot. What is the general principle here that Hogg neglected to mention?
I don't recall everything he mentioned, but the part you are missing is the part why the number of ticks is a scalar for D in that one sequence of events: the lack of separation in space between D's clock and planet A when the journey starts, and the lack of separation in space between D's clock and planet B when the journey is over. E's clock has no similar closeness to A or to B.
Clock ticks are scalar only if you are on earth, looking at a distant clock, but clock ticks are NOT scalar if you are looking at an earth clock from the same distnce in space? That it?
No.
Ignores, eh? Why would it ignore a crucial aspect of understanding the relativity principle, I wonder?
It's interested in the effects that can be derived from a specific subset of the types of knowledge available.
Galileo did NOT say that if you were in a closed ship cabin, you would have no way of knowing whether a bug moving across the cabin floor was really moving with respect to the cabin or if the bug was actually motionless while the ship moved.
Not really relevant.
while he knows beter because HE is the one who is motionless while she is moving and, guess what, HE IS CORRECT!
Correct in the sense that he is using a valid world view. The ontological sense of correctness you are inferring is not implied nor addressed.
One Brow said: "What about that assumption changes his measurement? If you have two people on a moving train, and both lay out 10 yards using a yardstick, both time the two-way speed of light over those 20 yards, will they get different amounts of time if one assumes he is moving and the other assumes he is stationary? How do their thoughts affect the amount of time their clocks show? just what type of subjectivity are you pushing for here?"
It really doesn't take much thought to understand this Eric. Just read the physicist's explanation of why each one thinks the opposite about whether event A happened before event B. Analyze what he is saying, and why. Each knows how the other will (supposedly incorrectly) perceive the "true sequence," but why is that?
I assume from you lack of response to the question I acutally asked that you agree their clocks show the same thing, even though one thinks he is moving and the other does not think that. So, whether you think you are moving or not doesn't change what you observe.
As for the explanation of the relativity of simultaneity, each person can use the Lorentz transformations to determine how the other person observes the event sequence.
What would the guy on the train conclude about which event happened first if he assumed he was moving down the tracks?
He would conclude that observation suppporting that determination is dependent on the inertial state of the observer, and that if you add an ontological preference for a specific inertial frame, you can get a specific answer for that frame.
What conclusion would he arrive at about the speed of light, as perceived ("observed" in Hogg's nomenclature)from a moving train if he did that?
That the speed of light is c in either frame.
He would conclude that even though he "saw" the light from the front of the train first, it could not have actually occurred first if he assumes he is moving relative to the earth.
Right.
Al, on the other hand, tries to dictate that his subjective and uncorrected perception of which happened first must reflect "reality" and SR accordingly forbids him from adopting the view that the train is moving.
Wrong. SR is silent on adopting the view that the train is moving. It neither forbids nor requires such an adoption.
..., he has implicitly designated the earth to be the preferred frame. That CANNOT be allowed in SR.
Incorrect.
If that is done, the speed of light will be "observed" to vary from frame to frame, and NOT remain constant, once the deformed measurements are corrected.
Incorrect. The speed of light remains c in the frame where the earth is at rest.
Upon even rudimentary reflection anyone could easily understand that when he heard them, standing alone, says virtually nothing about when they happened.
Yup. Unless he knew exactly where the lightning struck for each thunderclap, and both of those distances to him where equal (as withthe case of the train). Then the one he hears first is the one that struck first.
By the way Eric, just so you know, I don't see your new posts unless I make a post myself.
It might be a page caching issue. Try refrshing (on Internet Explorer, that's ).
Plenty around, I'm sure. This one is from NPR:
This did not discuss an experiement where the clocks compared rates while one clock was in motion. However, that sort of experiement should be easy to do now.
Do you think Hogg is not aware of such effects, and provides answers based on a lack of such corrections? I don't.
Nor do I. Do you have anything from Hogg that says D will not observe 50 ticks from E's clock when D over the time D completes her journey.
Why didn't Hogg say we both only see 100 ticks on his clock because of unaccounted for loss of signals from time delay and otherwise we would have seen 200? Instead he says the ticks are invariant to all observers.
The ticks on D's clocks are invariant to all observers between two specific events in which D's clock is effectively not separated from said events by distance. These conditions don't apply to E's clock.
That's why I said that the only natural implication would be that the space traveller would see 200 (not 50) ticks on our clock if that's how many times we saw our clock tick.
Natural or not, it's wrong.
Unless you assume a lack of reciprocity for a scalar effect,
E has no events to make his number of ticks a scalar. He can't piggyback on D's events, because his distance from them is not negligible.
based on the mere presumption of reciprocity of frames that is what you would expect him to see.
You misunderstand reciprocity.
Light delay doesn't occur on a one-way only basis, unless perhaps you think that assertion would help you "prove" your point.
If you go back to my example of the color-chaning lights, you'll notice I used light delay in both directions to describe the effects.
Show me the physicist that says the time of the physical event which leads to observers later hearing a thunderclap is NOT determined in accordance with the time at the place it happened, but rather only in accordance with when it is heard by various observers.
If you have observers in different locations, you can use the separtion of the thunderclaps each observers experiences to pinpoint their locations, but I don't think that is what you meant. Nor is what you seem to have meant relevant to discussing mainsteam SR, because mainstream SR does not claim the observations of the person control the timing of the lightning strikes.
The LT tells you (you don't have to believe it, of course, but either way it tells you) that the moving clock will always be slower,
But they can't tell you which clock is moving. so they can't tell you which clock is slowed until the clocks are both in the same reference frame again. Just like SR.
The LT do not claim to apply ONLY IF you personally believe you know
Well, duh.
One Brow said: "The only circumstance that allows you to determine whether events are truly simultaneous or not is when the events in question have a neglible distance between them. Your characterization here is wrong. I have no idea why you think this is a postulate of SR."
1. Al's "light synchronization" scheme posits and assumes a one-way speed of light that have never been verified and which is essential to his denial of isotrophy in all frames and the rejection of a Galilean type of transformation.
2. I know that you really don't think in any other terms that what you already believe, Eric, but there is not a shred of "relativity of simulataniety in SR. There is never a question or doubt about which events are simultaneous.
2.
One Brow said: "Which postulate is different for LR?"
As I already said, "I must make the distinction between "theorems" and postulates here because, I agree with the author's analysis who concluded that, from a mathematical perspective, LR and SR are identical theories."
That restated, (1)Al's relativity principle does not apply in SR (Galilean relativity applies), (2) and the speed of light is not the same in all inertial frames.
aintnuthin said...
1. Al's "light synchronization" scheme posits and assumes a one-way speed of light that have never been verified and which is essential to his denial of isotrophy in all frames and the rejection of a Galilean type of transformation.
A. No light synchronization scheme is a postulate of SR.
B. SR is based on isotropy in all inertial reference frames. I do agree that isotropy can't be verified.
2. I know that you really don't think in any other terms that what you already believe, Eric, but there is not a shred of "relativity of simulataniety in SR. There is never a question or doubt about which events are simultaneous.
Such determinations can only come from SR for events that have a neglible separtion of distance, or after the preferred reference frame has been fixed.
That restated, (1)Al's relativity principle does not apply in SR (Galilean relativity applies), (2) and the speed of light is not the same in all inertial frames.
LR doesn't use Galilean relativity, either, because the compressed rods mean that the velocities will not be additive between reference frames. If (2) were really a part of LR, you could perform a Michael-Morley experiment on a moving track and different speeds of light in the direction of travel versus the direction perpendicular to travel.
Unless, you mean that LET adds in some ontological postion about a locally absolute reference frame that makes some of the measurements more real than others. So, LET would be an extension of SR.
One Brow said; "I don't recall everything he mentioned, but the part you are missing is the part why the number of ticks is a scalar for D in that one sequence of events: the lack of separation in space between D's clock and planet A when the journey starts, and the lack of separation in space between D's clock and planet B when the journey is over. E's clock has no similar closeness to A or to B."
Where did Hogg say that? Where did I miss it? Where does he say it applies to only this example? Where does he say a single thing about proxmity to a planet. Where does Hogg even begin to suggest that it is a scalar only in this particular circumstance?
You are just making up "facts" that Hogg never mentioned as you go. He is using this example to illustrate length contraction, so we're not talking about perpendicular motion. For all we know, Earth is exactly halfway between A and B on the line that connects them.
I don't buy a word of it, Eric, and I have no clue what your basing your unqualified assertions on. Not any math calculations, I'm sure. You act like he's going half and inch to get from A to B, but it wouldn't make any difference either way. The ticks on his clock are what they are, as the number of those ticks are invariant to ALL observers, all over the universe. How does him being close to a planet, assuming he was, have a thing to do with that? We're close to a planet too--in fact we're on one.
One Brow said: "His distance from our clock causes his seeing fewer ticks than we see, not his distance from the planets. D's distance from the planets is what allows both of us to see the same 100 ticks of D's clock for the same events. But if it doesn't affect the number of ticks seen on E's clock."
One Brow said: "His distance from our clock causes his seeing fewer ticks than we see..."
And his distance from us is different than our distance from him, somehow? We BOTH see 100 ticks on his clock, whatever the distance, an equal amount, but he sees 50 (four times as many) on ours as we do? How is the reciprocal LT being applied here? It does seem the least bit reciprocal the way you tell it.
Do you have anything other than raw assertion to back this up? Simultaniety, or lack thereof, has NOTHING to do with counting his ticks the same the whole universe over, that I could imagine.
Quit bluffing. Say or do something to demonstrate or prove (i.e., explain how it works and why it's relevant) your claim, citing a credible source). I don't care how cocksure you are (or try to act), you haven't said a single which supports anything you've claimed. Light delay.....heh.
One Brow said: "A. No light synchronization scheme is a postulate of SR."
Are you just quibbling about words, or what? I never said it was literally a postulate, in fact I said it wasn't, back when, if you care to read it. All it a "stipulated definition of simultaniety," "the Einstien synchronization convention," a theorem, an axiom, or whatever the hell you want. He makes assumption about the behavior of light that are essential to his theory and which have never been proven, and in fact, are deemed to be untestable.
Al, on the other hand, tries to dictate that his subjective and uncorrected perception of which happened first must reflect "reality" and SR accordingly forbids him from adopting the view that the train is moving.
Wrong. SR is silent on adopting the view that the train is moving. It neither forbids nor requires such an adoption.
Yes it does. Unless you adopt "your" frame of reference (by defintion absolutely motionless with respect to all else), Al's relativity principle will not hold for you. To be consistent, you (on the train) will take the earth's speed 186,000, and transform it to yourself, and get a speed for yourself which does not equal 186,000 mps. Like the guy we accelrated to .99c. He will not impute that transformation to the earth, but rather to himself if he considers himself to be the one moving and the earth not moving. His clock will the the moving one, not the earth's. He will regard his own clocks as misleading and deceptive, and will contract that he is now moving .99c with respect to the earth, not vice versa, and he will no longer give an credence to his distorted measurement readings. As a consequence, he not "observe" the speed of light to be 186,000 mps vis-a-vis his own frame.
..., he has implicitly designated the earth to be the preferred frame. That CANNOT be allowed in SR.
Incorrect.
If that is done, the speed of light will be "observed" to vary from frame to frame, and NOT remain constant, once the deformed measurements are corrected.
Incorrect. The speed of light remains c in the frame where the earth is at rest.
Sure, for the earth. But it won't be what he "observes" (as opposed to merely measure) the speed of light to be with respect to the train frame he's inhabiting.
Even when you make a speficic pretense to looking at the issue from something other than an ultra-orthodox SR viewpoint, Eric, it seems you still want to pre-emptorily settle all issues by assertions of "fact" drawn straight from SR.
Not for the guy on the train, it don't.
One Brow said: "Unless, you mean that LET adds in some ontological postion about a locally absolute reference frame that makes some of the measurements more real than others."
In LR there is a preferred (not absolute) frame, just as there always is in SR. This frame is used as reference point for establishing consistent standards, just as astronomers routinely use the CMB these days. Time does NOT change from frame to frame. I've already summarized this.
Time and distance still gets (mis)measured in different frames, but those distortions get corrected in LR, whereas SR relies on uncorrected distortions to superficially establish an insubstantial "appeance" of the constancy of light, in order to claim laws of physics are the "same," because of the postulated constancy of light, when they're actually not (for that reason).
One Brow said: "Yup. Unless he knew exactly where the lightning struck for each thunderclap, and both of those distances to him where equal (as withthe case of the train). Then the one he hears first is the one that struck first."
The crucial qualification and "flaw" what you just said was "to him were equal." Al himself shows just why it is a mistake for him to think is at (an remains at) the "midpoint" of the train when he is moving. He wouldn't make that mistake if he had the least bit of sense, and then it would no longer be "equal to him." He would then know the one he "heard" (saw) first did not actually happen first other than by virtue of his mistake. Then it would no longer be "equal to him."
If he recognizes that he is moving, the relativity principle based on the "constancy" of the speed of light goes up in a puff of smoke "for him" at that point.
Of course Al doesn't allow him to recognize his mistake (even though Al, telling the story, clearly sees it). Al says something like "he can't help but judge" himself to be at the midpoint. Nice to have useful fools to co-operate with misjudgment to help you establish your theory, eh?
One Brow said: "You misunderstand reciprocity."
Maybe you can explain it to me, eh? What is that inverse (or "reverse") Lorentz transformation all about?
One Brow said: "If (2) were really a part of LR, you could perform a Michael-Morley experiment on a moving track and different speeds of light in the direction of travel versus the direction perpendicular to travel."
Yeah, ya sure could. And what would that tell you? What would you know then?
For ease of reference, "(2)" was:
"(2) and the speed of light is not the same in all inertial frames."
One Brow said: "2. I know that you really don't think in any other terms that what you already believe, Eric, but there is not a shred of "relativity of simulataniety in SR. There is never a question or doubt about which events are simultaneous.
I meant LR, not SR, in that post.
One Brow said: "So, LET would be an extension of SR."
You got it backwards. SR is an "extension" of LR, always was. There is no reciprocity of frames in LR, and there never was. They were not designed for that. Al chose to make them reciprocal so the speed of light can always be relative to YOU, but that was unwarranted.
You might ask yourself how the frames can NOT be reciprocal. And then you might ask yourself why anybody ever claimed they were in the first place, Then you might for once, carefully analyze these same "light clock" and "train" examples that have been used for almost 100 years now, and take the time to understand what they are really based on. Why about them makes you think any observer would ever "see" both clocks slow down? Do you realize that they "show" no such thing?
You also seem to have trouble with the notion that LR could possibly (in any consistent manner) keep time constant in all frames. Why is that?
One Brow said: "SR is silent on adopting the view that the train is moving."
Heh, it is, eh? I guarantee you that you will NEVER see one of these light clock or moving train presentations where the guy on the train does not get treated as motionless. Listeners are AlWAYS assured that he will "naturally" assume his frame in motionless (when what they mean is SR only works out if and when the "frame of reference" is universally motionless for every observer, who is always treated as adopting that exclusive view for himself--he has to, for their examples to work out). Of course they will also assure you that his viewpoint is equally valid and you will almost invariably be told that the relativity principle says you can't tell who is moving (it doesn't, but....).
I don't know if you're really that naive and uncritical (when you makes statements like this) or if you just think I am and will readily accept your glib assurances.
I said: "Galileo did NOT say that if you were in a closed ship cabin, you would have no way of knowing whether a bug moving across the cabin floor was really moving with respect to the cabin or if the bug was actually motionless while the ship moved."
One Brow said: "Not really relevant."
Not really revelant to what? Your philosophy? It's quite relevant to the issues I'm raising, but, of course, if you can't, or won't, understand those issues, you won't see the relevancy of anything which relates to them.
====
while he knows beter because HE is the one who is motionless while she is moving and, guess what, HE IS CORRECT!
Correct in the sense that he is using a valid world view. The ontological sense of correctness you are inferring is not implied nor addressed.
He's not? The guy who says everything he tells you is fact proven by experiment? The guy who makes the ontological claim that "you can never tell who's moving?" The guy who "guarantees" one of his commentators (who corrected him) that if a person A could look at person B's watch he would see something that SR says he wouldn't see?
This guy is a know-it-all who actually seems to know little and understand even less. Of course he's making ontological claims to (presumably impressionable) young students. Know-it-all thrive on making claims about "reality."
One Brow said: "I assume from you lack of response to the question I acutally asked that you agree their clocks show the same thing, even though one thinks he is moving and the other does not think that. So, whether you think you are moving or not doesn't change what you observe."
I didn't fully address your question because I was trying to get you to answer it for yourself. Of course knowing whether (or not) you are moving affects what you "observe" (in Hogg's useage). Here's one example.
It turns out that it takes light longer to go from San Francisco to New York than it does from New York to San Francisco. But it's the same distance, either way. Does this mean light goes slower one way than the other? It might well appear that way, and that would be what you "observed" if you didn't think the earth was rotating.
Likewise you would "observe" different amounts of time for light to go from the back of a train to the front, depending on whether you knew it was moving or believed it was standing still.
One Brow said: "
If you have observers in different locations, you can use the separtion of the thunderclaps each observers experiences to pinpoint their locations, but I don't think that is what you meant. Nor is what you seem to have meant relevant to discussing mainsteam SR, because mainstream SR does not claim the observations of the person control the timing of the lightning strikes."
"Mainstream SR" (our physicist friend and many others in his position) says that if a guy insists he's not moving on a train, and then, solely on account of the motion he denies exists, see one flash from the front (coming toward him) sooner that he does one from the rear, he will (erroneously) conclude that the one he's see first occurs first. And guess what? HE IS ABSOLUTELY CORRECT!
That's one problem with all these thought experiments. The "explainer" plays God, and sees and knows all things. He can explain to you exactly why the poor chump on the train is deceived by motion which he insists doesn't exist. But, then, they show how their theory is quite willing to call these mistaken assumptions "correct" (to get a relativity principle"). The chump's mistaken perception's end up being "the truth," so he does end up controling simultaneity and the "speed of light" with his misperceptions. The theory transforms his (mistaken) impressions into "reality."
I said: "He can explain to you exactly why the poor chump on the train is deceived by motion which he insists doesn't exist. But, then, they show how their theory is quite willing to call these mistaken assumptions "correct" (to get a relativity principle")."
And this exact same model of scenario permeates virtually every explantion of SR. First you must:
1. Establish 2 observers, each with their own unique "frame of reference." Recall that "frame of reference" is code for "motionless" in this context.
2. Now you start talking about one of them moving while they continue, (by virtue of the "frame of refence" they have been assigned) to see things as though they were both simultaneously motionless.
3. Now you have handy points of equivocation along virtually every front, which you can cleverly exploit to "prove" any point you want, just depending on what pieces of information you take from what frame of reference. Especially handy is that you at all times keep a third frame of reference in your back pocket which you can haul out as needed: The God frame of reference where you can point out what's really happening as needed.
These guys end up confusing themselves more than the hapless listeners they suck in, I swear. When every conceivable piece of evidence (subjective perception) can be called true, false, or "unknown" depending on your polemical requirements at the time, it's quite a rhetorical advantage. They all seem quite satisified with themselves after an extended journey into such sophistry, too. I guess it could be kinda fun....
I said: "That's one problem with all these thought experiments. The "explainer" plays God, and sees and knows all things. He can explain to you exactly why the poor chump on the train is deceived by motion which he insists doesn't exist."
I want to try to be very clear about what I'm saying here, Eric, because I've said it repeatedly, but you have seemed to understand what I'm saying yet.
1. All their insistence that "you can never tell who's moving notwithstanding," there's always a guy in these SR problems who knows exactly who is moving, when, why and where. That guy is the one who is explaining just how SR works.
2. This guy always foists upon the useful idiots (aka "observers") who he exploits for his explanation some false and/or mutually exclusive assumptions which he requires them maintain throughout his explanation. He then exploits the ignorance of the fools he just created to show what's really happening, and to thereby explain how and why the theory works.
3. But the question that never gets answered after he's all done is this: Why do you make a physical theory that is premised on known errors and then insist those errors are "true?" What's up with that?
You should be able to tell from that that I'm simply talking about SR as a theory. Forget entirely about whether or not SR is "true" as an ontological matter--that's entirely irrelevant to what I'm saying, either way.
What I'm saying is that, as a theory, SR relies on the adoption of mutually contradictory premises on the part of it's theoretical (not ontological) observers to establsh it's premises and dictate it's conclusions. Without that, the explanations, examples, and illustrations of how SR "works" will not lead to the necessary and desired conclusions. Without that, there will be no "observation" of light as being constant in all inertial frames.
In all these explanations, if the observers don't mutually assume they are at rest, none of that will work out. We know one of them is moving, but we're not allowed to make use of our knowledge, other than to explain why our observers are mistaken. But, again, they have to remain forever deceived about the state of their own motions for the "explanations" to hold.
These "light clock" examples used to "explain" time dilation and length contraction are nothing new. Scientists have been easily resolving such "puzzles" for centuries without violating the relativity principle and without "seeing" someone else's time and length being distorted in any way.
The "solution" is simple in each such case. An observer in one intertial frame will simply not observe a moving object in another frame as having the same speed (relative to him) as the oberserver in the other frames see it as having (relative to him). No mysterious warping of time and space required.
====
That said, it remains (best we can tell) an objective physical fact that lengths and clocks get distorted with speed. Given that fact, the examples of SR serve admirably to illustrate and explain the types of psychological consequences that can result, and the types of incorrect conclusions an observer can arrive at, if when his perceptions are affected by motion which he assumes isn't there.
Like the last post, this post is really designed to anticipate and "respond to," in advance, what I assume some of your responses might be to the things I've said.
Some people think the genius of Al was that he came along and said: "Looky here: We measure the speed of light to be the same in all inertial frames so here's my brilliant insight: Let's just say it IS the same in all inertial frames of reference, whaddaya say!?"
It certainly wouldn't take a genius to come up with that proposal, and it wouldn't solve anything.
If it actually IS the same, now you have created a new problem. Now you have to explain how, if it is the same, we can possibly also measure it to be the same in all frames. If it "really is" the same speed in all frames, then we couldn't possibly measure it to be the same.
It really doesn't solve this problem to go on, as Al does, to explain how rods and clocks become deformed with motion. That does, in fact, explain why we "measure" it the same, but now it excludes the claim that it "really is" the same. All that is implying is that you start out by comparing two speeds which are "really" different, but end up measuring them as the "same" only because you do not use consistent standards of time and distance to do so.
If it were as simple as "the speed of light REALLY IS the same in all frames of reference," then you would not have any transformation formulaes in your theory. They would all have to be chucked out. To incorporate a transformation formula into your theory that the speed of light "really is" the same in all reference frames would be to refute your own theory.
I said: "To incorporate a transformation formula into your theory that the speed of light "really is" the same in all reference frames would be to refute your own theory."
Al certainly saw that. Of course he also didn't ever claim that the speed of light "really is" the same in all inertial frames of reference. He simply noted that it is measured to be so, then went on to explain how the the distortion of rods and clocks was therefore necessarily implied.
I should add that, for a while, Al wasn't adverse to, and even kinda endorsed, the logical positivistic claim that "a yard is whatever a yardstick says it is." In that limited and indirect sense, Al might be interpreted as having pretended, for a while, that the speed of light "really is" the same in all frames. By that (throroughly discredited) standard of thinking, a speed "really is" whatever your measuring instrument say it is.
Al later posisitively rejected such a naive view, of course. He was a young disciple of Mach when he came up with SR. Later, after independently reflecting on Mach's claim at greater length, he saw the completely solipsistical implications of the claim.
I said: "The "solution" is simple in each such case. An observer in one intertial frame will simply not observe a moving object in another frame as having the same speed (relative to him) as the oberserver in the other frames see it as having (relative to him). No mysterious warping of time and space required."
I mean think about it. If a guy going past us in a car going 50 mph and, from it, throws a baseball out in front of it at 50 mph, he sees the ball moving 50 mph relative to him while we see it moving 100 mph relative to us. Why don't both parties immediately "see" that time and/or distance have both "obviously" been cut in half for the other guy? Hmmmmm?
I don't know where you could find a more explicit analysis showing that the observer's in SR do not both "see" the other's clock running slow. In fact, they both see the moving clock running slower, and the stationary one running faster. All the "seeing" is not based on sense perception at all, but based solely on elaborate deductions from (unproven) premises as I've been telling you for weeks while you deny it:
"Suppose that in Jack’s frame we have two synchronized clocks C1 and C2 set 18 x 108 meters apart (that’s about a million miles, or 6 light-seconds). Jill’s spaceship, carrying a clock C', is traveling at 0.6c, that is 1.8 x 108 meters per second, parallel to the line C1-C2, passing close by each clock.Suppose C' is synchronized with C1 as they pass, so both read zero. As measured by Jack the spaceship will take just 10 seconds to reach C2, since the distance is 6 light seconds, and the ship is traveling at 0.6c.
"If both Jack and Jill are at C2 as Jill and her clock C' pass C2, both see that his clock reads 10 seconds, hers reads 8. How, then, can Jill claim that Jack’s clocks C1, C2 are the ones that are running slow?
"Jill will conclude that since C2 reads 10 seconds as she passes it, at that instant C1 must be registering 6.4 seconds. To settle the argument, the two of them agree that as she passes the second clock, Jack will be stationed at the second clock, and at the instant of her passing they will both take telephoto digital snapshots of the faraway clock C1, to see what time it reads.
Jack, of course, knows that C1 is 6 light seconds away, and is synchronized with C2 which at that instant is reading 10 seconds, so his snapshot must show C1 to read 4 seconds. That is, looking at C1 he sees it as it was six seconds ago.
What does Jill’s digital snapshot show? ...Jill must also gets a picture of C1 reading 4 seconds.
How can she reconcile a picture of the clock reading 4 seconds with her assertion that at the instant she took the photograph the clock was registering 6.4 seconds? The answer is that she can if she knows her relativity!"
What follows is a bunch of elaborate deduction (e.g., "she deduces that at the instant she took the photograph the clock must actually have been registering 6.4 seconds, which is what she had claimed all along!") by Jill. So, it seems, she manages to deduce for a second time the same thing she deduced the first time. Well, now, aint that special, eh?
The author then claims that despite what they both see with their own eyes on their own and each other's clocks and despite what they both see in the picture of the other clock which they both took, Jill must be right in maintaining that Jack's clock is running slow, if you assume the constancy of the speed of light, anyway:
"The key point of this lecture is that at first it seems impossible for two observers moving relative to each other to both maintain that the other one’s clocks run slow. However, by bringing in the other necessary consequences of the theory of relativity, the Lorentz contraction of lengths, and that clocks synchronized in one frame are out of synchronization in another by a precise amount that follows necessarily from the constancy of the speed of light, the whole picture becomes completely consistent!"
http://galileoandeinstein.physics.virginia.edu/lectures/time_dil.html
aintnuthin said...
Where did Hogg say that?
I don't know if he explicitly said that or not, but it's a part of the relativity of simultaneity.
Where did I miss it?
Pretty much from the beginning.
Where does he say it applies to only this example?
It applies between any events that seem simutaneous to all observers, but again, I don't know that Hogg says that about this example.
Where does he say a single thing about proxmity to a planet. Where does Hogg even begin to suggest that it is a scalar only in this particular circumstance?
Again, it's a result of the relativity of simultaneity.
For all we know, Earth is exactly halfway between A and B on the line that connects them.
Changes nothing about what I said.
I don't buy a word of it,
OK.
The ticks on his clock are what they are, as the number of those ticks are invariant to ALL observers, all over the universe. How does him being close to a planet, assuming he was, have a thing to do with that? We're close to a planet too--in fact we're on one.
The issue is not the planet itself. Itg could be something as simple as D turning his light on, it makes 100 ticks, and then changes color. Everyone will see those same 100 ticks before the light changes color, because the spacetime separtion has become zero. Observersin different inertial states will see a different number of ticks on E's clock while they count the 100 ticks on D's clock.
And his distance from us is different than our distance from him, somehow?
No.
We BOTH see 100 ticks on his clock, whatever the distance, an equal amount, but he sees 50 (four times as many) on ours as we do? How is the reciprocal LT being applied here?
If we are seeing his ticks move at half the speed of ours, he is seeing our ticks move at half the speed of his. You're right that I didn't pull out the full-blown Lorentz transformations to do that math, but that's how it would work out regardless.
Do you have anything other than raw assertion to back this up? Simultaniety, or lack thereof, has NOTHING to do with counting his ticks the same the whole universe over, that I could imagine.
It's similar to the moving train example. D observes D's clock to make 100 ticks before D observes E's clock to make 100 ticks. E observes E's clock to make 100 ticks before E observes D's clock to make 100 ticks. However, both see D's clock make the 100 tick before it changes color (or whatever the events are).
Say or do something to demonstrate or prove
If I were still trying to persuade you of something, I would.
He makes assumption about the behavior of light that are essential to his theory and which have never been proven, and in fact, are deemed to be untestable.
No light synchronization scheme is essential to SR, either.
One Brow: Wrong. SR is silent on adopting the view that the train is moving. It neither forbids nor requires such an adoption.
Yes it does. Unless you adopt "your" frame of reference (by defintion absolutely motionless with respect to all else), Al's relativity principle will not hold for you.
Wrong. Regardless of whether you assume you are moving or not, you will still measure the speed of light to be c, and inertial experiments will still have the same result.
As a consequence, he not "observe" the speed of light to be 186,000 mps vis-a-vis his own frame.
Relativity does not claim that speed of light is constant when using different inertial frames at the same time, so your example does not violate mainstream SR.
Sure, for the earth. But it won't be what he "observes" (as opposed to merely measure) the speed of light to be with respect to the train frame he's inhabiting.
However, SR does not claim light is a constant when you use different inertial frames at the same time to make the comparision.
In LR there is a preferred (not absolute) frame,
Just locally absolute. Serves as an absolute frame for a local area. One frame to rule them all. Got it, thanks.
just as there always is in SR.
Mainstream SR is silent on frame preference.
The crucial qualification and "flaw" what you just said was "to him were equal." Al himself shows just why it is a mistake for him to think is at (an remains at) the "midpoint" of the train when he is moving.
I am unaware of any interpretaion of SR or LET where the man would be at the midpoint of the train when it is at rest, but the same point would not be the midpoint when the train is moving. Of course, you put it in quotes, so who knows what you mean here?
He would then know the one he "heard" (saw) first did not actually happen first other than by virtue of his mistake.
One frame to rule them all, locally.
One Brow said: "You misunderstand reciprocity."
Maybe you can explain it to me, eh? What is that inverse (or "reverse") Lorentz transformation all about?
E sees D in motion relative to E. E will use the Lorentz transformations on x, y, z, t to create x', y', z', t' which describe E's obsdervation of D. D will use the same transformations the same way on his X, Y, Z, T to create X', Y', Z', T' to describe D's observations of E.
One Brow said: "If (2) were really a part of LR, you could perform a Michael-Morley experiment on a moving track and different speeds of light in the direction of travel versus the direction perpendicular to travel."
Yeah, ya sure could. And what would that tell you? What would you know then?
That experiment would fail, and (2) would turn out to be wrong. The speed of light will turn out to be the same in all inertial frames, and it is only by mioxing different inertial frames together that you can get a different speed.
Why about them makes you think any observer would ever "see" both clocks slow down?
Mainstream SR does not claim any observer would see both clocks slow down.
You also seem to have trouble with the notion that LR could possibly (in any consistent manner) keep time constant in all frames. Why is that?
Not at all. As a locally absolute theory, the time elapsed in the locally absolute reference frame is used to measure time in all frames. Nohting troubling about it.
One Brow said: "SR is silent on adopting the view that the train is moving."
Heh, it is, eh? I guarantee you that you will NEVER see one of these light clock or moving train presentations where the guy on the train does not get treated as motionless.
I agree. The difference being that one is "adopting the view" with the other is "get treated as". The first being an ontological statement, the second is not.
I don't know if you're really that naive and uncritical (when you makes statements like this) or if you just think I am and will readily accept your glib assurances.
Neither.
Not really revelant to what? Your philosophy?
Mainstream SR, which takes no position on whether the bug or the ship is really moving.
It's quite relevant to the issues I'm raising,
Your issues are based upon insisting that a description of what peole experience, observe, and measure is an ontological commitment, and what's relevant to them is founded upon that error.
but, of course, if you can't, or won't, understand those issues, you won't see the relevancy of anything which relates to them.
They are based on a misunderstanding.
One Brow: Correct in the sense that he is using a valid world view. The ontological sense of correctness you are inferring is not implied nor addressed.
He's not?
Or, if he is, he's mistaken. Individuals often confuse ontology with epistemology.
The guy who says everything he tells you is fact proven by experiment?
A definite category error.
I didn't fully address your question because I was trying to get you to answer it for yourself. Of course knowing whether (or not) you are moving affects what you "observe" (in Hogg's useage).
You are very, very confused on Hogg's usage. Hogg is referring to correcting for angles of observation and similar things. He does not mean using an inertial state other than yhour own to base your observations in.
I'm not responding to another large section where you again insist that a description of what people measure and observe is suppsed to be an ontological declaration.
3. But the question that never gets answered after he's all done is this: Why do you make a physical theory that is premised on known errors and then insist those errors are "true?" What's up with that?
Because they are not errors, they are what is detectable to the guy on the train.
You should be able to tell from that that I'm simply talking about SR as a theory. Forget entirely about whether or not SR is "true" as an ontological matter--that's entirely irrelevant to what I'm saying, either way.
SR is primarily epistemological to begin with, being about what people can see and measure.
What I'm saying is that, as a theory, SR relies on the adoption of mutually contradictory premises on the part of it's theoretical (not ontological) observers to establsh it's premises and dictate it's conclusions.
Yes, I know that's what you are saying. You've said it many times, always based on a false that SR indicates some final ontological status.
But, again, they have to remain forever deceived about the state of their own motions for the "explanations" to hold.
No, their state of motion merely has to remain locally undetectable.
The "solution" is simple in each such case.
A solution in search of a question.
All that is implying is that you start out by comparing two speeds which are "really" different, but end up measuring them as the "same" only because you do not use consistent standards of time and distance to do so.
One frame to rule them all.
I mean think about it. If a guy going past us in a car going 50 mph and, from it, throws a baseball out in front of it at 50 mph, he sees the ball moving 50 mph relative to him while we see it moving 100 mph relative to us. Why don't both parties immediately "see" that time and/or distance have both "obviously" been cut in half for the other guy? Hmmmmm?
Because they can compare clocks and yardsticks that were the same when the car was not moving, and they very close to the same.
I don't know where you could find a more explicit analysis showing that the observer's in SR do not both "see" the other's clock running slow. In fact, they both see the moving clock running slower, and the stationary one running faster. All the "seeing" is not based on sense perception at all, but based solely on elaborate deductions from (unproven) premises as I've been telling you for weeks while you deny it:
So, why not do a test where you can watch a stationary clock while you move away from it, and see if you see it running faster or slower? If you watch the clock, rather than look at your formulas, you will see, observe, visually perceive, watch, etc. the clock run slower while you move away. No equations needed.
The author then claims that despite what they both see with their own eyes on their own and each other's clocks and despite what they both see in the picture of the other clock which they both took, Jill must be right in maintaining that Jack's clock is running slow, if you assume the constancy of the speed of light, anyway
That is what Jill would observe, see, watch, perceive visually, etc.
One Brow said: Heh, you still can't, after all this discussion, make consisent and meaningful distinctions between those things, eh? Eric, you have the philosophical sophistication of a third grader and the philosophical dispostion of a rank and file member of the KKK.
Any statement, hypothetical proposition, suggestion, etc. which does not itself fully and completely presuppose that the pre-existing assumptions, opinions, and "facts" which you have been led to adopt, undigested, and assimilate completely into your thought patterns is totally incomprehensible to you.
You kinda remind me of a guy I used to sit next to in civics class. If we were given a question calling for a short or essay answer, or which involved computation or calculation, he was never very confident and performed poorly. But when it came to true/false questions, he had them down pat! He would go straight down the list authoritatively proclaiming "that's true, that's false," etc.
Thing is, he also performed poorly on those too, but it never fazed his self-assurance. He would always just insist that the teacher was wrong about what was true and false because the teacher neither understood the question nor the answer. He could never say quite why he was right and the teacher was wrong, but that's the way it was, sho nuff.
aintnuthin said...
One Brow said: Heh, you still can't, after all this discussion, make consisent and meaningful distinctions between those things, eh?
Which two things?
I'm sorry, it really wasn't very polite of me to make comparisons of you to third graders and Klansmen, eh? That was just hyperbole, but underlying that, it's true, as I see it. It wasn't just a gratutious insult.
It seems to be that your thought patterns and your disposition is much better suited to assertion, advocacy, and engagement in a competive contest than it is to the dispasionate analysis of concepts with a view to gleaning a better understanding and insight into you own beliefs, and those of others.
One Brow said: "Which two things?"
It wasn't just two things. I intended to quote a specific reply of yours but forgot to insert it before I responded. But I don't say that because of any one, or even any dozens, of particular comments. Your last series of comments is typical of a long-standing pattern, and I see that, in light of your particular interests, it's really not worth discussing any of this further anyway.
No worries, I didn't feel insulted.
It does seem like we're talking past each other. I've been trying to respond to you by pointing out what I consider to be mistaken assumptions on your part, but it hasn't registered. I feel no need to continue.
See you around, I hope.
I'll go ahead and post a few more thoughts on this topic, Eric. If you care to respond, I hope it's in the same vein that I'm pursuing. When discussing this issue, I start with a few preliminary guidelines, such as:
1. LR and SR are empirically indisinguishable. Therefore it does little to say, for example: "LR can't possibly be right, because it doesn't agree with SR, and SR has been experimentally confirmed." The reverse is equally true: It is empty to say that SR can't be right because it doesn't agree with LR. Such arguments are not really "arguments" at all, at least not on any scientific level. Nor are they "arguments" even on a philosophical level. Such statements just serve to assert (without arguing for) one's philosohical preferences, even at that level of discourse.
2. There are reasons the two can't be distinguished. Why can't they be? Isn't there *some* way to tell the difference? Most authorities seem to agree that, in principle, no, there isn't. That alone is a topic worth pursuing, in my opinion, because if you're confident that you understand that, then the "difference" between the two becomes clearer.
3. Since they can't be empirically distinguished it seems to follow that the differences between the two are not empirical in nature. What does that tell you about the nature of the theories to begin with?
4. The primary difference between the two, as I see it, is that SR postulates that the speed of light is constant in all inertial frames, and LR doesn't (while acknowledging that the speed of light will be "measured" to be the same in all frames. Most (but not all) SR advocates seem to ignore (or even deny) any meaningful difference between what the speed of light *is* and what it is measured to be. This is one aspect of the "SR philosophy" that I reject.
5. As a practical matter, the difference between the different postulates ends up being that in SR the speed of light in constant while the conception time (and space) changes, while is LR the conception of time is constant, so the conception of the speed of light in each frame changes. There are a number of philosophical reasons why I think the SR view is suspect.
6. There are two sides to that debate, of course. What are the best reasons, respectively, for preferring one view over the other, and how does the opposing side attempt to argue that it's preferences are philosophically superior? Those are the questions that interest me more than, for example, reciting what I think the mathematical outcome of a specific SR or LR question would be (it would be the same either way). Again, I see it as misguided to try to argue that the "physical facts" are what determines why one is superior to the other.
In the sense that a change in either can cause changes in objects, motion and temperature seem to have a lot in common. Difference in temperatures can cause lenths to contract and cause the rate of physical processes to slow down.
Why is it that we don't say that "time" changes with each infintesimal change in ambient temperature? If a pendulum clocks slow down or speeds up with changes in temperature, hasn't "time" changed to the same degree, if any, that "time" changes with motion?
Again, why is it that we don't say that a single thunderclap occurred at different times if different observers heard it at different times?
I disagree with your claim that "SR" takes no position on whether a bug or the ship floor is moving. I think SR does, at least by necessary implication, take the position that you can tell which is moving("SR" being distinct, as a raw theory, from the claims of interpreters thereof). But, assuming it doesn't, why doesn't it? Every other physical science (including all of physics) treats the difference as discernible. Is SR different from physics? Is it it's own brand of "study" that is independent of, and aloof from, all other disciplines, like maybe EST or Moonieism? Is it a brand of "knowledge" that cannot be accurately be categorized under the rubric of "physics?"
Galileo noted that an observer on a moving ship would see a cannon ball drop "straight town" if dropped from the mast (just as a light clock observer that is moving with his clock sees the light beam go straight up and down) whereas an observer on the shore would see the ball taking a (longer) parabolic path (just as the outside observer of the light clock sees the same light taking a longer path).
Why didn't Galileo simply conclude that time and distance change in every frame of reference? You suggested before that the difference was not significant at slower speeds, but that is irrelevant. A longer path is a longer path, either way. Why didn't he "see" time slow down for the people on the ship? Because he was just stupid, ya figure?
If a guy in a car sees a ball moving at 50 mph relative to him, and we see it moving at 100 mph relative to us, why, again, don't we conclude that time has been cut in half for him?
Back to the temperature analogy: slight variations in temperature may result in immeasurable differences in the duration of phsyical processes and the length of objects, which may only be acute when extreme temperature changes occur. But either way, we don't alter our concepts of time and distance because of that. We don't say that every temperature has it's own unique standard for time and distance, so as to end up with an infinite number of "standards" for time and distance. Why not?
An infinite number of "standards" is the equivalent of no standards whatsoever. How is it possible to make any meaningful or coherent claims about anything at all if there are no standards by which to evaluate them?
If we say water boils at 100 celsius at sea level, then it necessarily "boils" at different temperatures at higher or lower elevations. Why don't we simply say it "always" boils at 100c, it's just that a degree celsius changes every time you change your elevation by an inch, or less?
If, on earth, you aim a missle straight at a target due south of you, you will miss it. That's because the earth is rotating, of course, and by the time the missles get to the destination in the direction it was pointed, the target will have moved.
From one perspective, the missle follows a curved path and misses the target for that reason--it didn't go straight. From another perspective, the ball travelled as straight as an arrow, it's just that the target moved. Which one is "right." Do you really want to say that "neither" could possibly be right, and then contend that your basis for saying that is because "it's all relative." Do you really want to say that we have no way of detecting whether the earth is rotating and that the question is therefore meaningless?
Whether the path the missle follows is curved or straight, one fact remains: You can hit the target you're aiming at if you make compensations in your aim for the expected movement by the target. How can that be, if the whole issue is "meaningless" because motion is undetectable?
aintnuthin said...
I'll go ahead and post a few more thoughts on this topic, Eric. If you care to respond, I hope it's in the same vein that I'm pursuing.
I appreciate your attempt to change approach.
h agree with points 1-3, overall. I did want to point out one thing this means: if you ave two of those very sensitive aluminum clocks adjacent and calibrated to each other, and you move one of them (clock A) across the room, each will observe the other clock as running behind it. That is, clock A will observe clock B running 1 picsecond behind clock A, and clock B will observe clock A running 1 picosecond behind clock B. It is not until you start to move clock A back to being adjacent to clock B that clock A will observe clock B to be running faster than it, so that clock B is ahead of A when A has been returned. This is a result of mainstream SR (and LET, to my understanding). You seemed to think it would be otherwise.
I think 4. is digging into those philosophical preferences you referred to in 1. For example, even while acknowledging there is a possible difference between the actual speed of light and the properly measured speed of light, I would also say that the actual speed of light is actually, really 299,792,458m/s in all inertial frames, and that this is part of mainstream SR. In 5., I would say that the conception of time and space does not change, but rather the orientation/juxtapostion between two distinct inertial states causes each to observe the effects of SR in the other.
I've already mentioned a couple of things about the LET version that I find very difficult to accept, such as the effects of turning a yardstick while it's moving, and changing the direction of its compression without heat. These don't trouble you as much as aspects of SR. No big deal there.
Why is it that we don't say that "time" changes with each infintesimal change in ambient temperature? If a pendulum clocks slow down or speeds up with changes in temperature, hasn't "time" changed to the same degree, if any, that "time" changes with motion?
One reason would be that cold affects different clocks in different ways under different conditions. If you remove all the moisture from the inside of an hourglass, and time it to the same interval as a water clock at 70 degrees fahrenheit, the hourglass will run faster than the water clock as 35 degrees. You can measure changes in the vicosity of the water (or the stiffness of the pendulum in your example) that are not time-related. By contrast, the effects of relativity affect all clocks and all potenial clocks in exactly the same way.
Again, why is it that we don't say that a single thunderclap occurred at different times if different observers heard it at different times?
We generally don't assign two different times to a single event, for starters.
If we say water boils at 100 celsius at sea level, then it necessarily "boils" at different temperatures at higher or lower elevations. Why don't we simply say it "always" boils at 100c, it's just that a degree celsius changes every time you change your elevation by an inch, or less?
I understand your point. It's still based on the notion that rod shrinkage and clock slowing is a physical effect within the rod and clock. Mainstream SR doesn't see it that way, rather, it says there is no physical effect within the rod and/or clock. So, it sees itself using the same standard throughout.
If, on earth, you aim a missle straight at a target due south of you, you will miss it. That's because the earth is rotating, of course, and by the time the missles get to the destination in the direction it was pointed, the target will have moved.
I think you meant, that if you aim a missle to it will move due south, it will miss a target that is due south of you. I agree with that. However, you don't actually aim at the target in this case. To get the missle to go due south, you'll wind up aiming behind the target.
Do you really want to say that we have no way of detecting whether the earth is rotating and that the question is therefore meaningless?
I've been saying all along there are methods of making that detection.
I disagree with your claim that "SR" takes no position on whether a bug or the ship floor is moving. I think SR does, at least by necessary implication, take the position that you can tell which is moving("SR" being distinct, as a raw theory, from the claims of interpreters thereof).
I would like to note the difference between saying "you can tell which thing is moving" and "you can tell from processes x, y, and z which thing is moving". It is quite possible to for the first to be true and the second to be false.
But, assuming it doesn't, why doesn't it? Every other physical science (including all of physics) treats the difference as discernible. Is SR different from physics?
SR is one theory in physics. Very few scientific theories incorporate every single aspect of a discipline in science.
For example, if you are using population genetics to predict the likely frequency of blue flowers in the fourth generation of plants in your lab, you probably won't use the percentage of blue plants in that same species found in a meadow outside your window. Nothing is stopping you from goinng outside and sampling flowers, but you don't need to do that to get accurate predictions.
Similarly, just because you have a method of determining a true inertial rest frame does not mean you actually have need of that frame, or that you derive any particular benefit from it.
Why didn't Galileo simply conclude that time and distance change in every frame of reference? You suggested before that the difference was not significant at slower speeds, but that is irrelevant. A longer path is a longer path, either way. Why didn't he "see" time slow down for the people on the ship? Because he was just stupid, ya figure?
Because the people on the ground can actually measure the ball going faster than the guy on the ship measures it. This is unlike light, where each person measures it to be going c, independently.
An infinite number of "standards" is the equivalent of no standards whatsoever. How is it possible to make any meaningful or coherent claims about anything at all if there are no standards by which to evaluate them?
I agree. However, physicists don't use an infinite number of standards, they adopt a specific standard. For example, to measure a meter, they use the wavelength of light from various sources. That would be consistent in all inertial frames.
One Brow said: "It is not until you start to move clock A back to being adjacent to clock B that clock A will observe clock B to be running faster than it, so that clock B is ahead of A when A has been returned. This is a result of mainstream SR (and LET, to my understanding). You seemed to think it would be otherwise.
No, I didn't think otherwise at all. But SR is not just a new way of descibing the doppler effect, known for centuries. That's not at all what is being addressed when the claim is that each "sees" the other's clock as running slow. It's not the least bit relevant to the theory, nor is the "delay in light speed" what it's about. Those are both long-known effects, which can adjusted for and easily compensated for. Hogg notes that you must make those adjustments, and ONLY THEN can you get to the claims SR makes about clocks.
One Brow said: "I would also say that the actual speed of light is actually, really 299,792,458m/s in all inertial frames, and that this is part of mainstream SR. In 5., I would say that the conception of time and space does not change, but rather the orientation/juxtapostion between two distinct inertial states causes each to observe the effects of SR in the other."
That's all very easy to "say," but I don't comprehend a word of it. It seems to simply misperceive the problem that drove Al and many other brilliant minds crazy for years--There is no conceivable way for light to "actually be" the same speed in all frames AND to have it be measured by each observer as the same--not without changes the standards for measurement. On the other hand, if you measured it differently, then it could easily be travelling at a single speed that simply appears different in all freames. Whatever is speed is measured "relative to," that speed has to be identical to itself. One ball cannot "really" travel at two different speeds (measured consistently)simultaneously.
Take the case of a guy in a moving car throwing a ball that we discussed. If it appeared to both observers that the ball was travelling at 100 mph, then they couldn't really be moving with respect to each other. If the ball is only going at one speed (whether to you it 50 mph, as measured from the car or 100 mph as measured from the stationary observer), they must measure it differently. Again, the basic premise that one ball cannot coherently be claimed to "actually" simultaneously travel at two different speeds?
Let's go back to a prior example: A guy passes us at .5c just as we send a flashlight beam in the direction of it's travel. One hour later, we say he has travelled half a light hour while the beam has travelled a full light hour, and that the two are now separated by a distance of 1/2 a light hour.
For him, in that same duration, he must measure it as though he had never moved an inch. He claims that light beam is just as far from him as we claim it is from us. It's as if he never moved from our spot when he passed us, in one sense.
You cannot logically say it "is" going the same speed relative to each of two relatively-moving observers. It can be measured that way, but it can't "be" that way. Not unless all motion is basically an illusion.
One Brow said: "SR is one theory in physics. Very few scientific theories incorporate every single aspect of a discipline in science."
Sure they do, at least implicitly. A "physical theory" can only be within the context of the entire realm of physics. I could come up with some perfectly (internally) consistent theory of motion or of mechanics, or whatever, but if, for it to be true, you had to ignore and contradicts all known effects of gravity, it would be flatly rejected, no matter how sensible it might seem in isolation from all other accepted physical "facts."
That is in fact the very kind of thing that is ultimately used to reject most otherwise plausible theories. A theory might be compatible with most known phenomena, yet be incompatible with, say, stellar abberation. The theory is therefore rejected, even though it never explicitly addresses stellar abberation internally.
One Brow said: "Because the people on the ground can actually measure the ball going faster than the guy on the ship measures it. This is unlike light, where each person measures it to be going c, independently.
I don't understand what you are saying here. How can he measure it to be going faster? If he measures it to be going faster, then aren't the "times" different in each frame? What's different about the light clock? Why doesn't the guy looking at the other's clock simply measure light as going faster that the co-mover does?
One Brow said: "However, you don't actually aim at the target in this case. To get the missle to go due south, you'll wind up aiming behind the target."
Yeah, that's exactly what I said. Do you think you are disagreeint with me? I didn't say that just to point it out--it was merely incidental to a different point I was making that you don't address at all.
One Brow said: "I've been saying all along there are methods of making that detection."
Yes, you have, but not consistently. If you ask me a series of true false questions and I respond to every one with the claim "that's both true and false," then whatever the correct answer turns out to be, I can claim to have got it "right."
If it's false, I simply say: "I said it was false."
One Brow said: "We generally don't assign two different times to a single event, for starters."
Well, I agree with this 100%, but you seem to have missed my implicit question. Why is simultaniety said to be "relative" in SR?
Let's take two cases--one as seen by SR, and one as usually seen.
Take a single event, like a lightning strike hitting the front of a moving train. A guy moving with the train will "see" the lightning flasher sooner than a stationary person on the ground. Does that mean it "happened" sooner? What is the simultaneity "relative" to? The perspective of the observer? That's always been true, always will be. No new insights from SR there. If the train rider stubbornly refuses to acknowledge his motion towards the light, then he will "conclude" that the light hit the front of the train at an earlier time than he would if he acknowledged his motion. It would have struck the front of the train at the same time either way, it's just his conclusions about when that happened that varies, depending on his assumptions. We don't say the time of the occurence has changed because of either (1) his motion or (2) his perception of his motion.
In contrast let's say sounds travels at a mile every 5 seconds. Eight seconds ago a thunderclap occured 2 miles away from a given listener. Two seconds ago, another thunderclap occurred 1/2 mile away from him. He will hear the one from two miles away first (in two seconds from now. So does that mean it occurred first?
Of course not, and no one would maintain that it did except a strict subjectivist. The "time" a thing occurred does not change according to the time a particular person hears it. Why should it be different in SR?
I said: "If the ball is only going at one speed (whether to you it 50 mph, as measured from the car or 100 mph as measured from the stationary observer), they must measure it differently. Again, the basic premise that one ball cannot coherently be claimed to "actually" simultaneously travel at two different speeds?"
I want to elaborate on this point because you never seem to consider it. Just to expand, lets say a guy going 50 mph in the opposite direction will perceive the same ball to be moving at a rate of 150 mph relative to him.
Now is the ball "really" going 50 mph while it's also "really" going 100 mph, while it's also "really" going 150 mph. Of course not, the "same" speed is merely perceived differently depending on perspective. Call that speed "x." Now determine the rate of speed that "x" refers to any way you want--relative to the sun, the moon, the earth, or a butterfly in the meadow. In each and every case x = x. X is identical to itself, in all cases. And it is ONLY BECAUSE x = x that we can accurately predict and understand how observers with different perspectives, will see the relative speed as being different. Only if x did not equal x could the ball "really" simultaneously be travelling at an infinite number of different speeds. But that makes no sense.
The only way it could "really" be going the same speed relative to all of them is if they are not moving with respect to each other. In any other case, the the only reason they can "measure" it to be the same is because they are using different standards of time and/or distance.
One Brow said: "I agree. However, physicists don't use an infinite number of standards, they adopt a specific standard. For example, to measure a meter, they use the wavelength of light from various sources. That would be consistent in all inertial frames."
Heh, once again you simply demonstrate your eagerness to assume the truth your own conclusions. We've already been through the ridiculous circularity of this definition. Such a definition makes it impossible to EVER test the validity of SR's main postulate because it assumes it as true (as all these professorial lectures do--which they acknowledge).
Light sometimes goes 38 mph. Does the length of a meter change accordingly? I know that is not a point against the claim you are making (which involves the postualted speed of light in a vaccum), but that carries it's own assumption. Many have explained the effect of SR based on the "quantum vaccum" which is NEVER a vaccum in the classical sense.
I agree, though. A standard yard is a yard only under specifically defined conditions (temperature, altitude, etc.) and the standard for a yard does NOT change when the temperature changes. If a yardstick contracts to 35 inches due to temperature, we will now say it's only 35 inches long, and not claim a yard is now 35 inches long. That's the whole idea behind standards--the standard doesn't change because the conditions in which they were established change.
On the other hand, SR says that every degree of change in relative motion has a different standard for time and distance--that the standard changes whenever external conditions change. Again, it's like saying that water AlWAYS boil at 100c, and that the standard for degrees changes with elevation, not the temperature at which water boils. Such a "standard" would be intellectually repugnant, even though it would allow you to make the exact same predictions about the differences in boiling points at different altitudes.
One Brow said: "I would like to note the difference between saying "you can tell which thing is moving" and "you can tell from processes x, y, and z which thing is moving". It is quite possible to for the first to be true and the second to be false."
Thank you for noting that, because that's what I've been saying all along. These are two different claims:
1. According to the principle of relativity, the laws of physics are the same in all inertial systems. Therefore there is no physical experiment you can perform in a completely closed and isolated system that will reveal to you whether you are moving.
2. According the the principle of relativity, you can never tell which of two parties is moving (see video "Dr. Kilmer's" experiment for the proof of this claim).
One Brow said: "One reason would be that cold affects different clocks in different ways under different conditions."
Well, I know what you're saying here, but, then again, its just a matter or perspective about what you call "the same" and what is "different." I can say, for example, that temperature changes have effects on all physical objects (that part is "the same") but that the particular changes vary. Likewise, I can say that although the particular changes are different in every inertial state, the fact that motion changes in every such state is "the same."
As far as I know, for example, reduced temperature always result in a decreased rate of metabolism and other biological processes for all species, even though the particular changes may vary from species to species.
For the purpose of "communicating" information between satellites and co-ordinating it with ground observers, the GPS standardizes time. For that reason, the speed of light is isotropic and standard in only one frame (the eci frame). For the satellites clocks, the speed of light in different directions is NOT the same, nor is the raw rate of it's speed the same as it is in the eci frame.
Why? Because that's the way they structured it. It was much easier to standardize time in accordance with a single standard, not a different standard for each frame (which, they say, would have been virtually impossible for practical purposes).
The consequence? The speed of light is not the same in all inertial frames, so Einstien's principle of relativity is lost. Who cares? We still all know and understand why the system works, and changing your postulates about the speed of light in all frames has no effect whatsoever on the behavior of light or it's "actual" speed.
Everyone acknowledges that it would be an insurmountable contradiction to claim that each of two clocks is "really" running slower than the other. But there is no inherent contradiction to saying that each of two different individual assumes that his clock is running slower than the other. There is no contradiction, because what is expressly and implicitly understood is that at least one of those two individuals is wrong.
Likewise, there is no inherent contradiction to saying that each of two individuals sees the other as moving and himself as motionless. Again, it is understood that individual can, and frequently do, err. And in such a case, at least one of them is in error. What would be inherently contradictory is to claim that each one "really is" at rest while the other is really moving.
A while back you said: "However, SR does not claim light is a constant when you use different inertial frames at the same time to make the comparision."
I'm not sure what you're claiming here. If we were only concerned with one frame of reference there would be no need for SR, which was specifically delevoped for the purpose of comparing the speed of light in different frames. My point is this: If both parties consider the other party to be moving, but not themselves, then they will deduce that the speed of light is the same in both frames. If however, they both assume that only one of the two is moving, and agree on which one is not, then they will not conclude that the speed of light is constant in all frames. They will agree, for example, that only one clock has slowed down, not both. From there a different speed of light relative to each observer necessarily follows.
One Brow said: "I've already mentioned a couple of things about the LET version that I find very difficult to accept, such as the effects of turning a yardstick while it's moving, and changing the direction of its compression without heat. These don't trouble you as much as aspects of SR. No big deal there.
The whole "length contraction in the direction of motion only" strikes me as bogus too, don't get me wrong. I would have no trouble at all rejecting both LR and SR if it weren't for certain empirical facts, supposedly confirmed experimentally and in practice, such as the fact that clocks really do slow down.
But one does not solve problems by denying that they exist. To glibly say that the speed of light "really is" c in all frames and to pretend that all difficult questions of physical interpretation of the claims about length contraction and time dilation just don't exist misses the point. As I've said, if there is no length contractions and/or time dilation, you're not going to measure the same uniform speed as being the "same relative to you" in all inertial frames. If it *is* the same speed, then you will necessarily measure it differently in different frames. If you measure it to be the same, then it is because the frames in question are NOT moving with respect to each other (absent distorted measurements). On the other hand, it you're simply relying on distorted measurements, then what you're really saying it that different speeds take on the appearance of being the same due to those distortions.
But you can't have it both ways--(1)no distortion at all, yet (2) the same speed relative to the observer in all frames. If you can't see that, then, sure, anything and everything is possible. They are no limits whatsoever imposed on what "can be."
Why does the guy moving at half the speed of light see the light beam moving away from him just as fast as we see it receding from us? According to SR, it's because of a combination of two factors:
1. He measures the distance travelled by the light beam as being longer than we do (because of length contraction, and
2. Because it takes a lot more time for the light beam to travel that shorter distance (time dilation)
If you don't like that explanation then reject SR, but don't claim that your contrary assertions are SR. They aint.
I said: "2. Because it takes a lot more time for the light beam to travel that shorter distance (time dilation."
I said that wrong. For him the light goes farther in what is less time, by our standards. If he sees that, the he's obviously going to think a slower speed is faster than it is.
I said: "My point is this: If both parties consider the other party to be moving, but not themselves, then they will deduce that the speed of light is the same in both frames."
I said that wrong too. You don't really "deduce" the constant speed of light from motion or anything else. You just posit it, if you so choose. But if you so choose, now you MUST conclude that the mover's clocks slow down and/or that distance (space) contracts for him. It is the perception of "simultaneity" that changes depending on whether you think you're moving or not.
This part was right though: "If however, they both assume that only one of the two is moving, and agree on which one is not, then they will not conclude that the speed of light is constant in all frames. They will agree, for example, that only one clock has slowed down, not both. From there a different speed of light relative to each observer necessarily follows."
The basic point is that if two different observers start with the same assumptions, they will reach the same conclusions about time and space. If you start with different (and mutually exclusive) assumptions, then, of course, then will reach different conclusions.
Suppose Galileo had said: "Whenever a ball is thrown by a human being, the speed of that ball, relative all observers in all states of inertial motion will always be 100 mph." What all would that entail to be true?
For LR, light is no different that any other object as far as relative speed goes. It's speed will appear different in accordance with the motion of the observer. But you will only see that once you correct for the distortions to clocks and rods that increased speed causes.
Sound like some big-ass coincidence? Yeah, sure does. Kinda like the coincidence between inertial and gravitational masses. Maybe their is some underlying connection. Here's another big-ass coindence.
A clock on the equator travels faster than a clock on the artic circle, and should therefore operate at a slower rate.
On the other hand, given the equatorial bulge, time should run at a faster rate at the equator due to gravitational effects.
As it turns out, these two opposite effect exactly cancel out at every point on the planet which is at the same elevation (say sea level). Not approximately cancel each other, but exactly cancel each other. Is there some unseen connection between the two sources of time distortion? Either that, or just one big-ass coincidence, who knows?
I said: "Suppose Galileo had said: "Whenever a ball is thrown by a human being, the speed of that ball, relative all observers in all states of inertial motion will always be 100 mph." What all would that entail to be true?"
Now carry that comparison over to the light clock explanations. Except this time we'll use a "baseball clock" which relies on a baseball bouncing up and down at a uniform rate of speed after being thrown be a human being. Does the outside observer still just see the baseball as travelling at a different rate of speed relative to him than it is to the co-moving observer? Well, that would depend. Does he believe that Galileo's claim is true? If so then the "natural" explanation cannot be correct. Now the other person's clocks must be presumed to have slowed down, his lengths contracted, or both.
Eric, I know the blogger network you're a part of was having a lot of trouble lately. I notice that now a lot of posts have disappeared. Are the two related? Do you have any way of restoring those posts? For other reasons, I did a "system restore" on my computer (to an earlier time) in the meantime, but I can't see how that could possibly affect what appears on your blog (but I don't know enough about computers to be positive).
A while back you insisted that Hogg could not be talking about a physical change in the object itself when speaking of length contraction.. As a Cal Tech physicist, I'm sure he is aware of such considerations as are elucidated in this wiki article:
"..heavy ions that are spherical when at rest should assume the form of "pancakes" or flat disks when traveling nearly at the speed of light. And in fact, the results obtained from particle collisions can only be explained, when the increased nucleon density due to Lorentz contraction is considered."
http://en.wikipedia.org/wiki/Length_contraction
To me, as a layman, that is the kind of interpretation (explanation, "confirmation," whatever you want to call it) that is a physical interpretation.
This same wiki article also notes that: "The Lorentz transformation geometrically corresponds to a rotation in four-dimensional spacetime, and it can be illustrated by a Minkowski diagram." How a physical phenomenon would "correspond to" lines on a Minkowski spacetime graph is, no doubt, of great interest to geometricians. I understand that, even if I don't share their interest in the topic. But a "rotation in four-dimensional spacetime" is not a physical explanation. It corresponds to geometrical notions, but it cannot serve as a physical explanation in my view. A physicist who wants to use geometrical notions to "explain" what "causes" physical phenomena has crossed the line from being a physicist to being a metaphysicist, if you ask me. Philosophical Platonists, or Pythagoreans, may see that kind of talk as incorporating a full and complete "real" explanation, but I don't.
One Brow said: "No. You are confusing the notion of the validity of a claim with an expression of ontological fact."
You repeatedly make this kind of assertion, so let me ask you a couple of questions to see if I understand what you are trying to say.
1. What kind of theory is SR? Is it a "physical theory" that makes some kind of pretense to explaining physical reality, or is it simply a topic of purely philosophical debate which makes no claim of having any kind of connection to anything empirical, such as the old medieval debates about how many angels can dance on the head of a pin?
2. What does the "validity of a claim" have to do with anything relevant to physics? What do you mean by this? If I say, as Mach did, that both a geocentric and heliocentric view of the motion within the solar system are "equally valid," how is that relevant to physics? What is the intended import of the statement, and how does it bear on considerations of "actual motions?"
Perhaps to put my question in a concrete context, let me go back to the "artillery shell aimed south" contrast.
From one perpsective, the shell curves while the target remains stationary. In such a case, one could say that the shell missed the target because, for some strange reason, it curved. When one sees this happen repeatedly, he may conclude that shells fired south always curve left (and shells fired north always curve right). Given that this is the way things are, he simply aims his shell to the right (or left, if north) of his target so that, after he fires, it will "curve into" his intended target. Presto. He accomplished his goal (hitting the intended target).
2. From another perspective, his shell is following a straight path, but the target is moving. If he therefore "leads" his moving target by the right amount, he will hit it.
Either way, he hits his target, so either interpretation of the phenomenon is "equally valid" in that sense, I spoze. And, in that sense, I suppose that the view that the shell is following a curved line is "equally valid" with the view that it is following a straight line. In the "curved" view, the shell would be perceived as going further in the same amount of time, hence it must have been moving faster (or else time slowed down). So, I guess, either view could be said to be "equally valid" in that sense too--one shell either goes faster than the other than the other, or else time either does (or does not) slow down, all just depending on how you want to look at it.
But what does that theoretical point have to do with whether the target is really moving or, alternatively, really curving? If nothing, then what's the point of bringing it up in a physics (as opposed to a philosophy) class? If something, then what is that "something?"
If the question of perspective is in any way relevant to objective reality (as far as what happens in the objective world) then wouldn't one need to explain how the choice of a subjective perspective by a given individual "causes" a path to either be curved or straight and/or "causes" time to slow down. How do an individual's assumption "change" those things? If an individual's subjective assumptions do NOT determine objective reality, then why make them the basis for a physical theory?
If a kid confuses the number 3 with 4, so that if hold up three fingers he tells you that's 4, and if you hold up 4 fingers, he tells you that's 3, but if he still tells you that 3+4=7, is his way or arriving at the answer of "7" equally valid with the "right" way of looking at the numbers 3 and 4? What does "equally valid" mean, as you use it? Just getting the same answer, no more no less? If that's all it means, then is each of two theories (or each of many theories) which give you the same answer "equally valid?" If not, who cares? Why bring it up? If so, then is any endeavor to distinguish two theories which give the same answer a fruitless, meaningless undertaking? Is physics just the equivalent of the "number of angels on a pinhead" way of passing time?
I know I was intending to come back to this guy, but can't remember if I ever did. Since a lot of posts are missing, I can't check to see if I ever did, either:
"How can she reconcile a picture of the clock reading 4 seconds with her assertion that at the instant she took the photograph the clock was registering 6.4 seconds?
The answer is that she can if she knows her relativity!
First point: length contraction. To Jill, the clock C1 is actually only 4/5 x 18 x 108 meters away (she sees the distance C1C2 to be Lorentz contracted!)."
1. This is what I was talking about when I spoke of mixing and matching frames in an equivocal way in order to reach the answers you want. From whose perspective does she see the "distance...to be lorentz contracted?" His, or her own? My understanding was that she would not see the distance, from her perspective (her "frame of reference") to be affected by a factor of 4/5 or any other factor. She therefore will not calculate answers based on a 4/5 ratio.
2. There is a difference between "length" and "distance" which often gets confused in these explanations. Here he says the "distance" is contracted, whereas lorentz only posits "length" (not distance) contractions. Length is the distance between two ends of a given physical object. Distance is the amount of space between two different physical objects.
As far as I know, Lorentz only posits "length" contractions, which affect the lengths of every "thing" (space is not a thing) in Mary's frame of reference--her hands, her rulers, her spaceship, etc. Distance, per se, does not contract, but the length contractions cause her to measure distances differently, even though they haven't changed.
To go back to the example where we see the guy who passed us at .5c to be only 1/2 a light hour from the beam we sent, while he sees himself to be a full light hour from it: If his rulers have contracted by 50%, then the distance to the light beam in front of him will NOT be different for him than it is for us. He will simply measure it to be twice as far away from him. Why? Because his 6" ruler will fit into that same distance twice as many times as our rulers would. So "distance" doesn't get contracted, even though you often (as with the guy quoted) see claims to the contrary. People often claim that "space" has contracted, but SR doesn't say that, does it? SR simply says he will measure that same distance to be different than we do, due to the length contraction caused by increased motion. That's how and why he thinks shorter distance is actually longer, and why he thinks he is 1 full light hour away from the beam.
Or do I misunderstand length contraction?
Hogg is saying the same thing I've been saying, as I understand him. I said that the reciprocity of frames is simply postulated and that Al's principle of relativity precludes the observer on the train and the observer on the ground from agreeing on who is moving. If they did so, the principle would fail, because, by assuming that he is moving relative to the earth he has implicitly designated the earth as a preferred frame, which would invalidate Al's relativity principle. Hogg puts it this way:
"D measures E’s speed to be u with respect to D’s rest frame. By symmetry, E must also measure D’s speed to be u with respect to E’s rest frame...."
OK, so far, so good. Yes, of course, the speed is, and must be, measured as symmetrical "with respect to" their respective REST FRAMES. But now he goes on...
"If they did not measure the same speed, which one of them would measure a higher speed? In order for one to measure a higher speed, one of them would have to be in a special or “preferred” frame; the principle of relativity precludes this."
So, as I said, Al's particular brand of the relativity principle precludes the assumption that the train is going at a "higher" speed than the earth, which is just another way of saying that the train traveller MUST consider himself to be at rest with respect to the earth if Al's principle of relativity is to be respected. For him to do otherwise the earth would implicitly be in a "a special or “preferred” frame." SR must therefore "preclude" the possibility of him considering himself to be moving.
The thing is, according to SR, as between the two, one of them HAS to be in a preferred frame--that would be the frame in which clocks have not been distorted (the frame which has not been accelerated) and in which they (the clocks) remain uneffected by the so-called "relative" motion of the train. Since the acceleration of the train is absolute, the "accelerated" speed of the train must also be "absolute," at least with respect to the earth. As between the two, only the train traveller will now age more slowly (experience time dilation), and that is only because the motion is NOT symmetrical (not merely "relative" or "relational").
Unless you deny the predictions of SR about asymmetrical time dilation, how can you disagree with the above analysis?
Our physicist friend resorts to all the tried and true means of evasion and denial that have been establised as "standard practice" by the relationalists of all stripes to "deal with" difficult questions. The most obvious is that he promises to answer the "profound" question he is asked but never does.
The question was (as I recall) "Doesn't one have to be going faster than the other?" As a matter of straight logic, the answer has to be "yes" unless they are going the exact same speed (which they can't be doing if they are moving with respect to each other). As a matter of the math and predictions of SR, the answer also has to be "yes," because only the faster clock will "really" slow down. So what answer does he give? NONE. Instead he makes an assertion that is contrary to the premises of every branch of physics: "YOU CAN NEVER TELL WHO'S MOVING."
This would be irrelevant to the question, even if it were true, which it aint. His purported "proof" of the proposition in fact proves the opposite. Does he even see what he's doing? Is he really that much of a philosophical hack and sophist, or is he just repeating all the things he was told. I suspect it is mainly the latter.
aintnuthin said...
Eric, I know the blogger network you're a part of was having a lot of trouble lately. I notice that now a lot of posts have disappeared. Are the two related? Do you have any way of restoring those posts?
No, I'm afraid I don't. Blogger has just lost them. This is one of the reasons so many people leave Blogger.
A while back you insisted that Hogg could not be talking about a physical change in the object itself when speaking of length contraction.. As a Cal Tech physicist, I'm sure he is aware of such considerations as are elucidated in this wiki article:
"..heavy ions that are spherical when at rest should assume the form of "pancakes" or flat disks when traveling nearly at the speed of light. And in fact, the results obtained from particle collisions can only be explained, when the increased nucleon density due to Lorentz contraction is considered."
http://en.wikipedia.org/wiki/Length_contraction
To me, as a layman, that is the kind of interpretation (explanation, "confirmation," whatever you want to call it) that is a physical interpretation..
It is a physical interpretation. It does not require a physical change in the object itself.
But a "rotation in four-dimensional spacetime" is not a physical explanation.
You don't think rotation is a physical process?
It corresponds to geometrical notions, but it cannot serve as a physical explanation in my view.
I understand this is your view. I see a rotation in four dimensionts to be just a physical an explanation as rotation in three dimensions can be.
One Brow said: "No. You are confusing the notion of the validity of a claim with an expression of ontological fact."
You repeatedly make this kind of assertion, so let me ask you a couple of questions to see if I understand what you are trying to say.
1. What kind of theory is SR? Is it a "physical theory" that makes some kind of pretense to explaining physical reality, or is it simply a topic of purely philosophical debate which makes no claim of having any kind of connection to anything empirical, such as the old medieval debates about how many angels can dance on the head of a pin?
It is a physical theory about what is observed and measured.
2. What does the "validity of a claim" have to do with anything relevant to physics? What do you mean by this?
It means you can form a consistent, usuable description of the universe, one which obeys all physical laws, regardless of which inertial frame you select as a rest frame.
If I say, as Mach did, that both a geocentric and heliocentric view of the motion within the solar system are "equally valid," how is that relevant to physics?
If you are referring to geocentrism versus heliocentrism specifically, geocentric depections of the sloar system violate other principles of physics, such as the conservation of energy.
What is the intended import of the statement, and how does it bear on considerations of "actual motions?"
It means that, as long as you consistently use a particular frame as the inertial rest frame, your selection any particular rest frame carries no physical significance.
From one perpsective, the shell curves while the target remains stationary. In such a case, one could say that the shell missed the target because, for some strange reason, it curved.
If you are going to fire the missle so it trravels due south, you will not have aimed it at the target in the first place. If you aim at the target that is due south, the missle will not travel due south to begin with. It keeps the eastward momentum of the firing station, unless you specifically take steps to counter it.
If nothing, then what's the point of bringing it up in a physics (as opposed to a philosophy) class?
The ability to use any inertial rest frame you choose is a physics issue. It renders the preference for a specific frame over any other a philosophical issue.
If an individual's subjective assumptions do NOT determine objective reality, then why make them the basis for a physical theory?
Subjective assumpitons are not the basis for SR.
"How can she reconcile a picture of the clock reading 4 seconds with her assertion that at the instant she took the photograph the clock was registering 6.4 seconds?
The answer is that she can if she knows her relativity!
First point: length contraction. To Jill, the clock C1 is actually only 4/5 x 18 x 108 meters away (she sees the distance C1C2 to be Lorentz contracted!)."
1. This is what I was talking about when I spoke of mixing and matching frames in an equivocal way in order to reach the answers you want. From whose perspective does she see the "distance...to be lorentz contracted?" His, or her own?
That was not very well-written, I agree. It would have been better to say 'the distance she sees for C1C2 is Lorentz-contracted compared to Jack'.
My understanding was that she would not see the distance, from her perspective (her "frame of reference") to be affected by a factor of 4/5 or any other factor. She therefore will not calculate answers based on a 4/5 ratio.
The author is trying compare what Jill sees to what she calculates Jack to see, as I understand it.
Length is the distance between two ends of a given physical object. Distance is the amount of space between two different physical objects.
That's an interesting distinction, but for SR it makes no difference. In SR, distance contracts just like length does.
As far as I know, Lorentz only posits "length" contractions, which affect the lengths of every "thing" (space is not a thing) in Mary's frame of reference--her hands, her rulers, her spaceship, etc. Distance, per se, does not contract, but the length contractions cause her to measure distances differently, even though they haven't changed.
The is true of LET or neo-Lorentzian relatvitiy, because of the adoption of a locally absolute reference frame, by which all distances are to be compared.
People often claim that "space" has contracted, but SR doesn't say that, does it?
It does, according to most physicists. It's one of the effects of the four-dimensional rotation.
"If they did not measure the same speed, which one of them would measure a higher speed? In order for one to measure a higher speed, one of them would have to be in a special or “preferred” frame; the principle of relativity precludes this."
So, as I said, Al's particular brand of the relativity principle precludes the assumption that the train is going at a "higher" speed than the earth, which is just another way of saying that the train traveller MUST consider himself to be at rest with respect to the earth if Al's principle of relativity is to be respected. For him to do otherwise the earth would implicitly be in a "a special or “preferred” frame." SR must therefore "preclude" the possibility of him considering himself to be moving.
Hagg was discussing why they measure each other to have the same relative speed. When measuring, you make all measurements from the inertial frame you are in. This is not the same thing as saying that you have to give your current inertial frame a priviledged position.
Unless you deny the predictions of SR about asymmetrical time dilation, how can you disagree with the above analysis?
You are assuming the earth was at rest, and the train is now moving faster. However, if the earth was not at rest, it is possible for the train to be moving 50 mph slower than the earth. So, perhaps they both started with "distorted" clocks, and now the one on the train is less distorted, or even correct. Then the train traveller will age more rapidly.
One Brow said: "It keeps the eastward momentum of the firing station, unless you specifically take steps to counter it."
But not at the same rate as the spot you're firing at. Different latitudes has different lineal speeds due to greater/lesser circumferences. A missle in the air with a north/south bearing does not "go east" at the same rate as does the ground under it. The old Coriolis effect, ya know?
What you perceive to be the "cause" of this depends on your assumptions about the rotation and curvature of the earth.
I said: "People often claim that "space" has contracted, but SR doesn't say that, does it?"
One Brow said: "It does, according to most physicists. It's one of the effects of the four-dimensional rotation."
Every account I've every seen of the lorentzian length contractions says it applies to "objects." Leave it to the metaphysical cult of minkowski geometricians to treat space as an "object" which shrinks, eh? The ironic thing is, these are the same mystical mathematicians that want to complain about Newton's sensible and innocuous notion of space. Why does space "contract?" Because some guy somewhere is moving, that's why. Well, actually, millions of guys in millions of places and "space" contorts itself to serve them all, simultanously. Heh.
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One Brow said: "When measuring, you make all measurements from the inertial frame you are in. This is not the same thing as saying that you have to give your current inertial frame a priviledged position."
No, it isn't, and that's not what Hogg is suggesting. "Your inertial frame" is not what would have to be privileged. It would have to be one of the two, not both.
But in one sense, yeah, every single frame of reference is always the "privileged" one in SR, it that's what you're saying. Every one is at rest. Both are at rest when there are two objects moving relative to each, and millions are all simultanously at rest with respect to all others when millions are moving. How much more "privilege" could "your" frame have, in that sense?
The point Hogg is making is the one I said he was making. For one to be going "faster" you would have to end the internal contradiction and stop saying that each is going faster than the other. SR precludes this, though. That would be making one of the two "privileged," just like the privileged twin who ages slower.
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One Brow said: "You are assuming the earth was at rest, and the train is now moving faster."
Not at all. I assume that the earth IS moving, just like the ship with the bug crawling across the floor. Both the train and the bug share equally in the inertial motion of the moving ship. It's just that the bug and the train then "add" something to that motion. It's called acceleration, ya know?
One Brow said: "However, if the earth was not at rest, it is possible for the train to be moving 50 mph slower than the earth."
Compared to what? Mars? Mars aint got nuthin to do with it. Or is this the forbidden (to all but the high priests of SR) "god frame" you're hauling out?
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