The basic scenario: clock1 and Jack are at rest, sitting six light-seconds apart, and Jack has a clock (clock2) synchronized to clock1. Jill, holding a clock, passes by clock1 traveling inertially at .6c and synchronizes her clock to clock1 (so they now both read 0), and them passes by Jack. When Jill passes Jack, her clock reads 8 seconds and Jack's clock reads 10 seconds. If you use the Lorentz Transformations (LT) from the view that Jill's inertial state is the rest frame, Jill gets 6.4 seconds for clock2. The disagreement is over whether the 6.4 seconds is supposed to be what jack sees on his clock, as far as I can tell. My answer is below the fold.
My response is that the 6.4 seconds is the time Jill measures for clock2, not the time Jack measures for clock2. You can show it is the former with basic algebra. First, because of light-speed delay, Jill sees jack's clock to read -6 when Jill passes clock1. As Jill passes Jack, her clock has gained 8 seconds while Jack’s has gained 16 seconds. Jill can use that and her relative velocity of .6c to tell how much time passes on Jack's clock for her, without using the LT. I will load a diagram to help illustrate this.
This diagram is based on clock2 sending out an image reading -6 and then an image reading -4, and Jill receiving those images 1 second apart in time. Jill can measure how far apart the images were when they were sent, and therefore how much time passed in Jill's frame between when the first image was sent and when the second image was sent.
In between the times when clock2 reads -6 and clock2 reads -4, the image of clock2 reading -6 travels at c (as measured by Jill), while the clock2 itself travels at .6c. (Edit: adding sentnces) That means the rate of separation between the image of clock1 readin -6 and the actual clock 1 is c-.6c, or .4c. Thus, the ratio of the distance traveled by the image of clock1 reading -6 to the distance traveled by clock1 is c/.4c, or 1/.4 (End of edit). Since the image of clock2 reading -6 and the image of clock2 reading -4 are 1 light-second (ls) apart, the total distance from where clock2 generates the image of -6 and where that image is when clock2 generates the image of -4 is 1/.4 which is 2.5 ls. Since the image of clock2 travels at c, the image takes 2.5 seconds to travel 2.5 ls. So, Jill measures 2.5 seconds to pass while Jack’s clock moves from -6 to -4, or two seconds. 2/2.5 = .8, so for every second Jill observes on her clock, she observes .8 seconds to pass on Jack's clock, the amount predicted by the LT. Over the course of all 8 seconds Jill observes on her clock, this becomes 8 * .8 = 6.4 seconds. Again, this is what she observes to pass on the clocks, not a prediction of what Jack observes.
To forestall an objection, none of this is an explanation for the time delay. It is only a measure of the time delay that Jill can make without using the LT.
(Edit: adding sentnces) I also want to note that Jack can use the exact same process to measure the time delay for Jill, without using the Lorentz equations. Jack does not see the image of Jill passing clock1 until 6 seconds after it happens, when his clock read 6. So, Jack sees the entire trip in 4 seconds. In that time, Jill's clock moves from 0 to 8. Jack can use the same logic as above to measure Jill's clock to tick off .8 seconds for every seconds of his. (End of edit).
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228 comments:
1 – 200 of 228 Newer› Newest»What does Jack see on Jill's clock using this "method?"
A few questions:
1. You first say "without using the LT," at one point, then later say "for every second Jill observes on her clock, she observes .8 seconds to pass on Jack's clock."
Where does the ".8" come from?
2. Who's frame tells her that only .8 seconds pass in her frame?
3. You say:"Since the image of clock2 reading -6 and the image of clock2 reading -4 are 1 light-second (ls) apart."
How does she determine that they are 1 light second apart?
4. You say: "Over the course of all 8 seconds Jill observes on her clock, this becomes 8 * .8 = 6.4 seconds. Again, this is what she observes to pass on the clocks..."
If she's looking at this second clock the whole time (beginning with "seeing" it read -6) why does she "see it" end up displaying (according to you) 6.4 seconds when it actually says 10 seconds when she gets there? She blind, that the idea? Or does she, like many people, have a way of "seeing" whatever she feels like seeing?
Physicists typically prove time dilation at very high velocities, don't they, OB?? And use the LT, which are not exactly algebra but calculus (the old delta notation in Einstein's own book on SR and GR, and space and time collapsed via Minkowski) ...Gold nuclei in an accelerator, etc. At even high speeds (supersonic jets) it is negligible--few nanoseconds. At 60% C...still negligible, wouldn't it be--though the different frames of references has been demonstrated empirically (ie the clocks in planes--no shit you probably say): either way, if the LT are not used, then's it's still the Gallilean-Newtonian tran.. So Jill (and Jack) needs to ramp her ride near to C, IMHE--tho another issue (yll probably scoff) presents itself.. would human vision/eyes even function near C? Not very well, if at all.
One Brow said: "The disagreement is over whether the 6.4 seconds is supposed to be what jack sees on his clock, as far as I can tell."
The issue arises from the question of what Jill, not Jack, sees on Jack's clock 2 when she reaches it (which is 10 seconds, not 6.4).
Why all this work to "prove" that she "sees" something that she does not see, and cannot see if she is moving, as is supposed?
I'm serious, Eric. You give an entire thread the heading
"Finding the delay of a clock without using the Lorentz transformations" and then, within seconds, you are using the lorentz factor of .8 to "prove" your claim.
All of this without ever realizing that you quickly disproved your own claim. What is it about your thinking process that leads you to such obvious self-contradiction, all while being oblivious to it? Ever try to answer that question? You really should.
Let me apologize for my last few comments. I couldn't follow your example and I thought you had drawn the .8 factor from the LT. I still can't follow it, but it does appear that you are getting the .8 figure by some other means.
I really can't follow your example at all, and get lost as soon as you say this: "is 1/.4 which is 2.5 ls."
Where does the .4 come from?
In any event, you have clearly overlooked the fact that each succeeding image will have less far to go to reach her.
To illustrate this, if the total distance for her in her frame is 4.8 light seconds, then, after 7 seconds, she will be only .6 light seconds away from clock 2. Yet you have tried to establish an implicitly "constant" travel distance of 2.5 light seconds for every subsequent image received.
By your reasoning, when she saw his clock read 8 (i.e. when her clock reads 7), it would have to travel 2.5 light seconds to reach her. How could it travel 2.5 light seconds if the TOTAL distance is only .6 light seconds?
The whole example is inherently illogical. I can see that much even if I can't discern how you arrive at your figures
I do think it shows something about your thought patterns, all the same. You start out with a goal in mind, i.e. to establish a "constant rate" of .8. As soon as you think you have found the "answer" you are seeking, all further reflection on your part ceases.
Eric, I don't think you'll understand this, but you seem to having completely ignored, or misunderstood, the crucial distinction Hogg was trying to make between "seeing" and "observering." You consistently claim to be honoring, respecting, and adhering to this distinction when you are in fact abusing it and crapping all over it.
Hogg is trying to make the crucial distinction between subjective and objective factors. Between fundamental (objective) differences and mere differences of perspective. He is insisting that all subjective factors be eliminated, not intensified and emphasized.
He says, for example:
"A common confusion for students of special relativity
is between that which is real and that which is apparent...How [moving things] appear depends on the particulars of the observation,
including distance to the observer, viewing angles,
times, etc...All apparent e ects, including the Doppler
Shift, stellar aberration, and superluminal motion...[should be separated] from the basics,
which are not dependent on the properties of the
observer."
What does he mean here by "the basics?" He is trying to distinguish the "fundamental details of
the observational procedure"(i.e., the "basics) from the "non-fundamental" ones (i.e., those which are dependent on the properties of the
observer).
One can only discover the "basics" by separating "real" (objective)phenomena from "apparent" (subjective) phenomena. He tries to illustrate the diffence in the context of length contraction:
"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...The observer nds that they are shortened
only after correcting for these non-fundamental details of
the observational procedure."
The above is from his introduction. In his text he uses the word "see" to encapsulate apparent, subjective factors. He says: "to see" will be reserved for
apparent e ects, or phenomena which relate to the fact
that we look from a particular viewpoint with a particular
pair of eyes."
In a somewhat circular fashion, he reserves the word "observe" as something which is applied to "real" effects. He says: "to observe" will be
used to mean "to measure a real effect with a correct experimental
technique." But even that "measurement" is a highly qualified one, because it applies to only a certain type of "observer," to wit: "an ideally knowledgeable
observer."
Therefore, what might, on the surface, appear to be an observation (measurement) could in fact just be the equivalent of a mere "appearance" if it is made by one who is less than "ideally knowledgeable."
In our case, Jill could make an accurate measurement which is NOT an "observation" by Hogg's definition. Any "measurement" she made which she believed indicated that Jack's clock was running slower than hers would have to be based on less than "ideal knowledge" because any such appearance is not of a "real effect." The fact of the matter is that her clock is running slower than Jack's, not the other way around. Furthermore, to the extent assumes she is stationary, she cannot be "ideally informed," since she is in fact moving.
Any attempt by Fowler to legitimatize her erroneous conclusions must therefore reduce to an attempt to make "mere appearance" seem "real" and to make what is mere "seeing" into an "observation" (which it aint).
That's one reason why I asked you why you are working so hard to "prove" that a false conclusion by Jill (that the time in Jack's frame was 6.4 seconds rather than 10) was a legitimate "observation." It can't be. It is not made by an "ideally knowledgeable" observer. Her conclusions are those of an "observer" who is fundamentally mistaken about her own state of motion.
I don't think you are capable of accurately and consistently separating "real" from "apparent" effects, because you don't appear to even think in those terms. For you, there are no "real" effects. All is mere appearance. All subjective sensations are "real" for you because they "really occur." You don't appear to even think in terms which presuppose an "objective reality." This was, of course, the mathguy's main beef against Dingle (who, by the way, changed his view when he matured, intellectually speaking, just as Einstien did).
You may pay lip service to the notion of an objective reality, but your thought patterns indicate otherwise. An underlying presumption that subjective phenomena are indicative of what you call "objective" reality and/or that "objective reality" does not exist seems to emerge in your claims. Many people think the same way. When that is their tacit assumption they can't really even think in terms of an objective reality.
Hogg, by the way, appears to be fully aware of where his distinction between "real" and "apparent" effects could ultimately lead.
He says, for example:
"By symmetry, E must also measure D's speed to be u with respect O@(to E's rest frame. If this is not obvious to you, notice that there is no absolute difference between D and E. 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."
Here he stops short of an "objective" point of view on the grounds that "the principle of relativity precludes this." That merely states that he is "respecting" the PR.
Elsewhere he says that: "When D is not moving with respect to E the
wristwatch and light-clock tick at the same rate, but when D is moving at high speed, they tick at different rates because, by supposition, one is time-dilated and the other is not."
Here he acknowledges the fact that the dogma of "mutual reciprocity" can't be literally true. Only ONE watch can be time dilated, not both. He goes on to say:
"D could use the relative tick rates of the watch and clock to determine his speed, and thereby violate the principle of relativity."
What does this mean? Putting it in the context of Jack and Jill I take it to mean this: Jill could acknowledge that her clock records 8 while Jack's records 10 (this would be the difference in the "relative tick rates") and thereby determine her speed relative to Jack (which is .6c, not zero, as she claims). But she can't do that because it is forbidden. To do so would be to "violate the principle of relativity."
So, here we are...First he acknowledges that time dilation is not mutually reciprocal. That implies a way to determine which one is really moving. Logically speaking, it would be an effective way of determining one's relative speed. But such logic is forbidden because that would undermine the principal of relativity.
Of course he does not, at any point, ever suggest rejecting the principle of relativity as a way of carrying his preference for measuring "real" effects to it's logical conclusion. He can't. He's there to teach SR, not question it.
J said...
Physicists typically prove time dilation at very high velocities, don't they, OB??
As clocks have become more accurate, the speed have decreased. A decade or two ago they did exeriments in airplanes.
And use the LT, which are not exactly algebra but calculus (the old delta notation in Einstein's own book on SR and GR, and space and time collapsed via Minkowski) ...
You only need calculus in situations when one or more objects are constantly accelerating (such as in orbit).
Gold nuclei in an accelerator, etc. At even high speeds (supersonic jets) it is negligible--few nanoseconds.
OK. Why does that matter?
At 60% C...still negligible, wouldn't it be--though the different frames of references has been demonstrated empirically (ie the clocks in planes--no shit you probably say): either way, if the LT are not used, then's it's still the Gallilean-Newtonian tran..
However, the Galileo-Newton translations give the wrong answers, as is wrong outside the error bars. At 60% of c, it's hugely wrong.
So Jill (and Jack) needs to ramp her ride near to C, IMHE--tho another issue (yll probably scoff) presents itself.. would human vision/eyes even function near C? Not very well, if at all.
Why would that be an issue?
It's been five years, Eric. I sometimes wonder: Did you ever wise up to the obvious fact that SR, while fine as a mathematical tool (a al Lorentz), has no coherent physical meaning?
aintnuthin,
If you want to claim shadows have no coherent physical meaning, or changes in orientation represent no coherent physical change, then in that same sense SR has no coherent physical meaning. However, if you think it means something physically to cast a larger or smaller shadow, that looking at a sheet of paper edge-wise is different from looking at it's face, then SR also means something physically. Personally, I don't see where it makes a difference if you label all three phenomena as having coherent physical meaning or not, as long as they all get the same label in that regard.
"If you want to claim shadows have no coherent physical meaning, or changes in orientation represent no coherent physical change, then in that same sense SR has no coherent physical meaning.
I should have known that you would respond to this question with a semantics slant. I'm not talking about abstract nominal concepts. I'm talking about meaningful physical substance. Substance, not form, not categorization. Concrete objective reality, not amorphous word phrases, ya know?
Onebrow said: "Personally, I don't see where it makes a difference if you label all three phenomena as having coherent physical meaning or not, as long as they all get the same label in that regard."
Ever read Plato's "allegory of the cave?" It goes something like this, as I recall:
People are in a cave, chained to their seats and restrained in such a way that they can only look at one wall.
Behind them is a huge bonfire. In front of that fire, but still behind the observers, are men behind a parapet wall holding puppets above the wall, so that the puppets cast shadows on the wall the observers can see.
According to Plato, the observers think they are seeing "reality" when all they are seeing is shadows of shadows (puppets). If you want to call subjective perception "reality," and if you want to say that every hallucination of a raving psychotic is "real to them," then we'd all know what you mean.
But to argue that you must equate subjective "reality" to objective "reality" would be, in Plato's opinion anyway, a monumental mistake.
My apologies, I was insufficiently clear. On the other hand, you have not been clear regarding what you think qualifies as a coherent physical change.
By "shadow", I meant the relationship of whether on object is in the path of the light between you and the light source. Does this relationship of being in the path of light between you and another object constitute, to you, a coherent physical phenomenon? If so, does the difference between being in the path of the light, and not being in the path of the light, in and of itself describe a coherent physical change?
By "orientation", I meant the facing in which you see an object. For example, a object in the shape of a rectangular prism that measures 100mm x 100mm x 1mm. If your line of sight to the object is perpendicular to a 100x100 base, it obscures much more of the background than if your line of sight is perpendicular to a 100x1 edge. Does the difference between these two orientations, in and of itself, constitute a coherent physical change?
If your answer to all of these questions is "No", then I would agree that, by the definition you are using, probably SR also does not described a coherent physical change. In all three changes (shadow, orientation, SR), any physical change comes from the relationship between the objects, and is not internalized within an object.
Eric, you're getting completely off track with respect to my question. You posit a three-dimensional rectangular object as a "whole" (100mm x100mm x 1mm), then ask if a partial view constitutes a coherent physical change. Is a part equal to the whole? No. But that's not even the point.
A subjective (limited) viewpoint is an actual viewpoint, sure, but what does a limited perspective tell you about the whole if that's all you have?
Hallucinations are "real" to the psychotic, sure. But that's where you get stuck. You want to make the "subject" the sole arbitrator of what is "real."
One thing I find rather incongruous in your thought patterns, Eric, is that you will readily concede that math has nothing to do with reality, per se. But, when it comes to SR, you insist that the math encapsulates "reality," when SR in inherently self-contradictory when it comes the the physical interpretation of the mathematical formulations it proffers (which by the way, are the very same formulations used by theories of relative motion which posit absolute, as opposed to relative, simultaniety--such as neo-lorentzian relativity).
What's up with that?
I've forgotten the details, but I'm sure you've heard the old fable about the 6 blind men who come across an elephant and each attempts to determine, but touch, just what kind of object they have stumbled upon.
1. The guy feeling the elephant's leg says it's a tree trunk.
2. The guy grabbing the trunk says it's a huge anaconda snake.
3. The guy grabbing the tail says it's a piece of rope.
4. Etc.
As with anything else. you must view SR from a holistic viewpoint, and not just ratify one part, or one part at a time while ignoring the implications that each solitary part adds to the totality. A thing cannot be BOTH a snake and a tree trunk. If given such conflicting assertions, you would naturally conclude that you're not getting the "big picture" from the limited information you're being supplied with.
When you refuse to acknowledge that any inconsistency exists, you are just being willfully ignorant. It doesn't help to say well, if one guy thinks it a tree then it IS a tree (to him) and if another thinks it's a snake then it IS a snake (to him). Both are absolutely correct, and both are basing their conclusions on a "coherent physical aspect of reality" so their subjective interpretations of that reality are irrefutable.
Know that I'm sayin?
I took the time to re-read the commments I posted in response to this thread 5 years ago. Almost all of them were designed to illustrate (using Hogg to help elucidate) the difference between objective and subjective considerations.
You have never responded to a word of it. I'm not sure why, but, as I repeatedly said above, I don't think it's a distinction that you have any real grasp on. Perhaps that is why you don't respond.
By hypothesis, Jill is the one moving in the instructor's example. Her denial of this fact is therefore mistaken, and should not be treated as being "true."
If, in fact, no one can ever know which of two objects is the one moving, then the instructor has no damn business presuming to know the unknowable. He should shut up, and say that relative motion is too mysterious to understand and concede that SR tries to elucidate a topic which it has, ab initio, proclaimed to be beyond the bounds of physical knowledge.
The folly here is clearly apparent in Einstein's own explanation of the basis for his claim that simultaneity is "relative." In his mature years, he was adamantly opposed to the type of positivism that he employed in formulating SR, but he never went back and corrected his earlier mistakes in this regard (although he did admit that a lot of what he said at the time was "nonsense").
Reference for my last post:
Werner Heisenberg "Encounters with Einstein (1926)
“To my astonishment, Einstein was not at all satisfied with this argument.... And when I objected that in this I had merely been applying the type of philosophy that he, too, has made the basis of his special theory of relativity, he answered simply: "Perhaps I did use such philosophy earlier, and also wrote of it, but it is nonsense all the same."
Einstein repeated the same sentiments in 1949, when writing a response to a collection of essays about him and his work.
"We represent the sense-impressions as conditioned by an “objective” and by a “subjective” factor. For this conceptual distinction there also is no logical-philosophical justification. But if we reject it, we cannot escape solipsism. It is also the presupposition of every kind of physical thinking....
"What I dislike in this kind of argumentation is the basic positivistic attitude, which from my point of view is untenable, and which seems to me to come to the same thing as Berkeley’s principle, esse est percipi." [my comment: To be is to be percieved--put another way, the moon does not exist unless we look at it--it has no independent existence].
https://www.marxists.org/reference/archive/einstein/works/1940s/reply.htm
Yet another example of Einstein mocking his own theory of SR as a Joke:
From Isaacson, Walter. (2007). Einstein: His Life and Universe. Simon and Schuster, NY (p. 332)
The following is an example of a conversation between Einstein and friend Philipp Frank that illustrates Einstein’s personal feelings towards emerging quantum theories.
Einstein: “A new fashion has arisen in physics, which declares that certain things cannot be observed and therefore should not be ascribed reality.”
Frank: “But the fashion you speak of was invented by you in 1905!”
Einstein: “A good joke should not be repeated too often.”
====
As a young man, Einstein was a devout disciple of the ultimate proto-positivist, Ernst Mach. He later ridiculed Mach's approach to physics. The quote from the last post was addressed to an essay by Percy Bridgman, a stout advocate of (the now discredited) "operationalism" expounded in his philosophy of science book "The Logic of Modern Physics" (1927).
The conversation between Frank and Einstein quoted here was generally directed against Bridgman's notion that only "operational definitions" (which were reducible to measurements) were acceptable to science.
Bridgman later said of his own theory: "I feel that I have created a Frankenstein, which has certainly got away from me. I abhor the word operationalism or operationism..."
Eric, you're getting completely off track with respect to my question. You posit a three-dimensional rectangular object as a "whole" (100mm x100mm x 1mm), then ask if a partial view constitutes a coherent physical change. Is a part equal to the whole? No. But that's not even the point.
My question is not about whether a view constitutes change, but a difference in orientation by one object constitutes change (more specfically, what you deem to be a coherent, physical change) in the relationship between the two objects.
Perhaps this is too detailed. To, can there be such a thing as a relationship between two distinct, distant object? If so, is this relationship in part a coherent, physical entity? If so, does a change in the orientation of one object constitute a coherent, physical change?
If you answer to any of these questions is no, then I will be happy to grant that, by your definition, SR talks about no coherent physical change.
A subjective (limited) viewpoint is an actual viewpoint, sure, but what does a limited perspective tell you about the whole if that's all you have?
A limited amount, obvious, but that's not really relevant to my point.
One thing I find rather incongruous in your thought patterns, Eric, is that you will readily concede that math has nothing to do with reality, per se. But, when it comes to SR, you insist that the math encapsulates "reality," when SR in inherently self-contradictory when it comes the the physical interpretation of the mathematical formulations it proffers (which by the way, are the very same formulations used by theories of relative motion which posit absolute, as opposed to relative, simultaniety--such as neo-lorentzian relativity).
If you treat the results of SR as ontological statements, the results are self-contradictory. If you treat them as epistemological statements, they are not.
Again, I make no commitment to the reality of a single grounding for all relativistic viewpoints. Whether you posit such does exist, or posit it does not, I don't see how it changes anything.
You seem to be assigning to me the position that there is no true reference frame. I don't take that position. For all I know, there may be an ultimate reference frame. There may not be one. Tell me how it makes a difference in my life (or the life of any human), and I will be more inclined to take a position.
For all your observations that I am taking a mathematical formula as reality, the reverse is true here. You seem to be insisting that one person is normal, and the other squeezed. I do not accept that.
I took the time to re-read the commments I posted in response to this thread 5 years ago. Almost all of them were designed to illustrate (using Hogg to help elucidate) the difference between objective and subjective considerations.
Is epistemology objective or subjective, as you areusing the terms here? SR discusses how things are measured (epistemology).
One Brow said: "If you treat the results of SR as ontological statements, the results are self-contradictory. If you treat them as epistemological statements, they are not."
Your definition of epistemology is apparently different than mine.
You also say: Is epistemology objective or subjective, as you areusing the terms here? SR discusses how things are measured (epistemology).
Taken alone this seems to imply that you think the question of "how things are measured" is synonymous with epistemology. Is that your definition?
Not that it really matters, as far as terminolgy goes, but I'm trying to understand what you're sayin.
I surprised to hear you say that SR is self-contradictory as a matter of ontology. I agree, but why do you say that?
I would also agree that the math used in SR is internally consistent and non-contradictory, if that's all you mean by epistemological (but again, I wouldn't personally use that term for it)>
One Brow said: "Tell me how it makes a difference in my life (or the life of any human), and I will be more inclined to take a position."
Does "science" make any difference in your life, or that of any other person?
As Bohm, J.S. Bell, and many others have pointed out, it would make a huge difference in our understanding of the physical universe.
As relatively recent article addressing this particular issue can be found here:
http://journals.plos.org/plosone/article/asset?id=10.1371/journal.pone.0115550.PDF
According to this author: "This study shows that a valid AST would have significant
implications for cosmology, including universal time dilation, increased ages and
distances for high-redshift objects, and a linear, non-accelerating rate of universe
expansion during the most recent era." [AST means absolute simultaneity theory)
The article I cited correctly (as far as I know) states that:
"The Lorentz transformation/ALT time dilation equation functions robustly in
conditions that have classically not been associated with Minkowski spacetime.
The Lorentz transformation/ALT equation can accurately calculate the time
dilation of objects traveling in non-inertial frames [12]. It can also accurately
predict the time dilation of muons traveling in a circular cyclotron using only the
speed of the muons as input; and this motion is, by definition, accelerated motion
[51]. Further, the Lorentz transformation/ALT equation accurately predicts the
time dilation of subatomic particles traveling through Earth’s atmosphere [52],
which is neither empty nor flat, with densities of matter and curvature of space
that are significantly higher than that found in intergalactic space. This wide
applicability is consistent with ALT for which there is no theoretical basis to limit
its application to inertial reference frames."
This is one reason why Einstein was dissatisfied with SR--It's application was too limited, too "special." He sought to make GR a theory of relative motion that also applied to accelerating objects and those in gravitational fields. According to most commentators, he failed in this goal. In GR, gravitational effects on time are absolute, not relative. That's the way it's always been for accelerating objects, i.e, the time dilation is "directional" (using this author's terms) not "reciprocal."
Aside from being ontologically ridiculous, the "reciprocity" requirement of SR will not hold up in most everyday (whether terrestrial or extra-terrestrial) circumstances. SR is so highly conditioned and qualified as to be useless as a practical matter. It is simply a "novelty," as far as physics goes.
This is just one more reason to adopt as AST theory in preference to an RST. SR incorrectly predicts the observed effects of experiments such as Hafele-Keating, whereas an AST, and only an AST, correctly predicts the outcomes.
This is true, notwithstanding the widespread claims that the H-K experiments served to "confirm" SR, which it does NOT. It does, however, confirm the legitimacy of the LT. SR adherents seems to think the LT are the exclusive domain of SR. But that just goes to show how little thought they put into the assumptions underlying SR. They routinely conclude that the employment of an AST is an application of SR. It aint.
" You seem to be insisting that one person is normal, and the other squeezed."
What does this mean?
"A limited amount, obvious, but that's not really relevant to my point."
What is your point, exactly? You're talking about something completely different than I am.
"...does a change in the orientation of one object constitute a coherent, physical change?"
Sure it's a change, but it "explains" nothing.
Suppose I'm sitting at my desk, then stand up and move two feet to the south. Is this a change? Sure, but so what? That's not the issue. Here's the issue:
Suppose you ask me how and why this "change" occurred and I responded along these lines: Some might think I moved, but they are wrong. I never moved one inch. What "really" happened was that
1.The earth turned 90 degrees. If you want to call "down" south, my feet were then facing east, and no longer south.
2.The back of my chair went from "north" to "west," and my back followed course, so then only my legs were bent, but the knees down.
3. Then a force pushed me forward to a standing position.
4. Then the entire earth shifted two feet to the north, leaving me in new, standing position, two feet south of my chair.
Although you might speculate that it's "theoretically possible" that this is the true explanation for the change in my posture and position, it would NOT be a coherent (plausible) explanation of the change. It is not within the realm of physical possibility as we know it to be.
I'm talking about plausible EXPLANATIONS of changed circumstances, not whether or not a change has actually occurred, as you seem to be.
If someone told me that "red is not red," I would say their claim is incoherent.
If someone told me that each of two clocks runs slower than the other, I would say the same.
Just in case it's not 100% clear, my last two posts were designed to elaborate on what I intended by the phrase "coherent physical meaning," which I thought was obvious from the beginning.
Coherent, as opposed to incoherent. Physical, as opposed to metaphysical or mathematical.
The endless sophistry, solipsism, and slavish adherence to incomprehensible dogma that I encounter when talking to those whose wish to defend SR as "objectively true" always baffles me. It's a cult, I tellya.
On a more general topic, I wonder why clocks slow down in a gravitational field and with increased speed. What causes that? I think we have some sensible physical theories as to why the shape of physical objects, and the rate of activity of their atomic components, vary with increasing/decreasing temperatures.
But what's up with gravity and motion? Why should gravity or motion affect a clock? Since, as far as I know, there is no widely accepted understanding of what "gravity" even is, I guess that alone makes it difficulty to say why it should affect anything.
Did you happen to notice that even Hogg is, indirectly by way of self-contradiction, confusing SR with LR? He say all of the following things:
1."... they tick at different rates because, by supposition, one is time-dilated and the other is not."
But, as incoherent as it is, SR says BOTH clocks slow down. Well, it says that until the time comes for it to solve an actual problem, such as the twin paradox, anyway. Only LR says what Hogg claims here, and only the application of LR gives a satisfactory explanation of the twin "paradox." There is no hint of a paradox when LR is employed.
2. "For instance, length contraction is often mistakenly thought to be some optical illusion. But moving things do not "appear" shortened, they actually ARE shortened."
LR says that lengths are shortened, which explains why those travelling at higher speeds get the same MEASUREMENT of the speed of light (which actually changes and is not ACTUALLY constant or isotropic in most frames of reference). Of course this lack of constancy is acknowledged by physicists when it comes to accelerated motion.
In contrast, SR says, in effect, that lengths (which applies to physical objects) doesn't change, but rather that space (distance, which is the measurement to the space BETWEEN two objects) itself changes (which is an absurd notion).
3. "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....D could use the relative tick rates of the watch and clock to determine his speed, and thereby violate the principle of relativity."
Of course here he is, presumably knowingly, referring to the methods employed by LR (or, more generally, what the other author called an AST). But he mistakes the the "principle of relativity" for Einstein's second, unproven, postulate, i.e., that the speed of light actually IS (not just appears to be, because of altered clocks and rulers) constant is all frames of reference. LR fully satisfies the "relativity principle,' so THAT is not (as Hogg suggests) what differentiates it from SR.
As I said above, if Hogg himself wanted to observe his own standards about what constitutes an "observation," as opposed to merely "seeing," (which is a subjective matter), he would say something like:
"Since lengths actually do contract (and clocks actually do slow down) an as OBJECTIVE matter, then we must discard the perceptions of a less than ideally knowledgeable observer who treats his measuring instruments as unaltered by his speed and deems them to be accurate."
I can't say for sure, but it appears to me that, much like his colleague who teaches physics at Harvard, Moran, Hogg appears to deem SR as being fundamentally false, even though mathematically self-consistent.
The principles of SR are NOT consistently respected when instructors purport to teach SR. They must resort to an LR perspective to even propose a hypothetical example where Jill's clock is slowing down because she is travelling faster than Jack. Einstein did the same thing (i.e., assumed that the train was moving) when he tried to explain the "simultaneity of relativity." But he had to prohibit the train passenger from acknowledging the state of motion which Al imputed to him in order to concoct his bogus concept. Al ratified, rather than eschewed, ignorance, in this example. He actually glorified it by making it (ignorance) mandatory for all SR observers.
These are some of the reasons why I say SR is "incoherent" as a matter of physics. Are they part of the reasons that you say that SR is "ontologically self-contradictory?"
Edit: In my last post i said "simultaneity of relativity."
It should be obvious, but I meant the "relativity of simultaneity." In SR, I suppose, the two expressions would refer to the same thing anyway.
Your definition of epistemology is apparently different than mine.
You also say: Is epistemology objective or subjective, as you are using the terms here? SR discusses how things are measured (epistemology).
Taken alone this seems to imply that you think the question of "how things are measured" is synonymous with epistemology. Is that your definition?
How things are measured, and what we learn of things from measuring, are epistemological concerns. I understand there is more to epistemology than that. Not "synonymous with", but "is one of subareas of". What branch of philosophy would you put measurement under?
Not that it really matters, as far as terminolgy goes, but I'm trying to understand what you're sayin.
I surprised to hear you say that SR is self-contradictory as a matter of ontology. I agree, but why do you say that?
More precisely, if SR consisted of statement of ontology, it would be self-contradictory, as (given objects with nearly identical measurements) each would be saying that the other weighed more, was slimmer, etc. This is not an issue because SR is not an ontological theory.
I would also agree that the math used in SR is internally consistent and non-contradictory, if that's all you mean by epistemological (but again, I wouldn't personally use that term for it)>
I agree that would be a poor usage of "epistemological".
Does "science" make any difference in your life, or that of any other person?
Sure.
As Bohm, J.S. Bell, and many others have pointed out, it would make a huge difference in our understanding of the physical universe.
As relatively recent article addressing this particular issue can be found here:
http://journals.plos.org/plosone/article/asset?id=10.1371/journal.pone.0115550.PDF
A quote:
In their experiment, atomic clocks were flown in airplanes eastward and westward around the Earth, and time dilation was calculated relative to the ECI [11, 12]. Flying eastward, in the direction of the Earth’s rotation, increased the speed of the airplane relative to the non-rotating ECI; while flying westward, in the direction opposite of the Earth’s rotation, produced a slower speed relative to the ECI.
These planes flew around the planet. They each would have flown faster and slower than the ECI during their journey, in about equal amounts. When your source makes a silly mistake about a detail and attaches importance to it, I find it unlikely to be worth my time to read the rest. You may think this hide-bound of me. I call it prudent.
The Lorentz transformation/ALT time dilation equation functions robustly in conditions that have classically not been associated with Minkowski spacetime. The Lorentz transformation/ALT equation can accurately calculate the time dilation of objects traveling in non-inertial frames [12]. It can also accurately predict the time dilation of muons traveling in a circular cyclotron using only the speed of the muons as input; and this motion is, by definition, accelerated motion [51].
While the equations of SR preceded those of GR, SR is still a simplification of GR. It's not surprising that a similar simplification of GR would appear independently in different contexts.
Further, the Lorentz transformation/ALT equation accurately predicts the time dilation of subatomic particles traveling through Earth’s atmosphere [52], which is neither empty nor flat, with densities of matter and curvature of space that are significantly higher than that found in intergalactic space. This wide applicability is consistent with ALT for which there is no theoretical basis to limit its application to inertial reference frames."
These rates of decay are also consistent with GR.
This is one reason why Einstein was dissatisfied with SR--It's application was too limited, too "special." He sought to make GR a theory of relative motion that also applied to accelerating objects and those in gravitational fields. According to most commentators, he failed in this goal. In GR, gravitational effects on time are absolute, not relative. That's the way it's always been for accelerating objects, i.e, the time dilation is "directional" (using this author's terms) not "reciprocal."
The effects of acceleration are also absolute, not relative. Do you mean Einstein was trying to make a theory where gravity and acceleration were relative? That would be doomed to failure, but that is not my understanding of the basis of GR.
Aside from being ontologically ridiculous, the "reciprocity" requirement of SR will not hold up in most everyday (whether terrestrial or extra-terrestrial) circumstances.
I agree that theories only apply in the circumstances that are assumed in their creation, and rarely will you have two distinct inertial frames each conducting their own measurements.
This is just one more reason to adopt as AST theory in preference to an RST.
Since you will rarely have two distinct inertial frames each conducting their own measurements, AST offers no advantage.
SR incorrectly predicts the observed effects of experiments such as Hafele-Keating, whereas an AST, and only an AST, correctly predicts the outcomes.
GR correctly predicts the outcomes, but I'm not so sure AST does.
This is true, notwithstanding the widespread claims that the H-K experiments served to "confirm" SR, which it does NOT.
The claim I saw is that it is consistent with SR/GR (aka GR), as opposed to SR on its own.
" You seem to be insisting that one person is normal, and the other squeezed."
What does this mean?
In AST, there is a frame which measures accurately that the other observer is squeezed in their direction of travel, and one measures the same thing, but inaccurately.
"A limited amount, obvious, but that's not really relevant to my point."
What is your point, exactly? You're talking about something completely different than I am.
My point is that the changes of SR come from differences in perspective (of a type), not differences physical characteristics, and that I take no position on whether this difference in perspective is a "coherent physical difference" or not.
"...does a change in the orientation of one object constitute a coherent, physical change?"
Sure it's a change, but it "explains" nothing.
It explains why you get a different measurement for the amount of surface area you can see. That's all I need it to explain.
It is not within the realm of physical possibility as we know it to be.
I'm talking about plausible EXPLANATIONS of changed circumstances, not whether or not a change has actually occurred, as you seem to be.
SR does not discuss nor predict changed circumstances. It is restricted to unchanging circumstances. You were just pointing that up above its scope is so limited as to be a novelty.
If someone told me that each of two clocks runs slower than the other, I would say the same.
OK.
Just in case it's not 100% clear, my last two posts were designed to elaborate on what I intended by the phrase "coherent physical meaning," which I thought was obvious from the beginning.
Coherent, as opposed to incoherent. Physical, as opposed to metaphysical or mathematical.
Philosophically, "coherent" means "internally consistent". Since SR discusses what two different observers measure, there is no incoherence. A has measurement x and y, B has measurements x' and y'. There is no inconsistency unless you add in the requirement that x = x' or y = y', but there is no reason to add this requirement.
Are measurements physical, metaphysical, or mathematical?
On a more general topic, I wonder why clocks slow down in a gravitational field and with increased speed. What causes that?
The short answers is "they don't".
I think we have some sensible physical theories as to why the shape of physical objects, and the rate of activity of their atomic components, vary with increasing/decreasing temperatures.
I don't think you can come up with a physical impedence theory that explains why the slowing is uniform against every type of time measurement tried. There is no reason atomic decay would slow down in lock-step to gears and springs based on temperature, ether, or anything else.
But what's up with gravity and motion? Why should gravity or motion affect a clock?
They don't affect the clock. They affect the path of the clock.
Only LR says what Hogg claims here, and only the application of LR gives a satisfactory explanation of the twin "paradox." There is no hint of a paradox when LR is employed.
The twin paradox relies on one twin (at least) taking a non-inertial path. SR offers no answer, because SR does not apply to non-inertial paths. By contrast, GR offers the correct answer to the twin non-paradox.
2. "For instance, length contraction is often mistakenly thought to be some optical illusion. But moving things do not "appear" shortened, they actually ARE shortened."
LR says that lengths are shortened,
Aka the moving object is squeezed.
which explains why those travelling at higher speeds get the same MEASUREMENT of the speed of light (which actually changes and is not ACTUALLY constant or isotropic in most frames of reference).
Just inertial frames in a vacuum, in both SR and LR.
Of course this lack of constancy is acknowledged by physicists when it comes to accelerated motion.
Yes, your measurements are affected by acceleration.
In contrast, SR says, in effect, that lengths (which applies to physical objects) doesn't change, but rather that space (distance, which is the measurement to the space BETWEEN two objects) itself changes (which is an absurd notion).
More accurately, your path through space-time (not just space) changes.
I can't say for sure, but it appears to me that, much like his colleague who teaches physics at Harvard, Moran, Hogg appears to deem SR as being fundamentally false, even though mathematically self-consistent.
Possibly.
Al ratified, rather than eschewed, ignorance, in this example. He actually glorified it by making it (ignorance) mandatory for all SR observers.
Rather, he said this particular knowledge had no effects on the measurements taken.
These are some of the reasons why I say SR is "incoherent" as a matter of physics. Are they part of the reasons that you say that SR is "ontologically self-contradictory?"
With the caveat above that SR is not an ontological theory.
"These planes flew around the planet. They each would have flown faster and slower than the ECI during their journey, in about equal amounts. When your source makes a silly mistake about a detail and attaches importance to it, I find it unlikely to be worth my time to read the rest. You may think this hide-bound of me. I call it prudent."
You call it prudent, I call it just plain wrong (what you're saying that is). The author is correct. Have you read the HF paper? Apparently not. You often do this. You deduce indisputable "facts" from your mistaken assumptions, then say that anyone who disagrees is "silly." You REFUSE to read the article if it disagrees with your mistaken preconceptions. You can't learn anything that way, eh?
The plane on the clock running eastward was slower, because it was going faster, and vice versa. This could not be explained by SR. Only an LR calculation using the ECI as the "preferred frame" correctly predicted this effect by the amount the clocks actually differed.
Think about it.
"Since you will rarely have two distinct inertial frames each conducting their own measurements, AST offers no advantage."
What!? An AST offers the "advantage" of making the correct prediction is ALL frames, not just inertial ones, caincha see?
"It explains why you get a different measurement for the amount of surface area you can see. That's all I need it to explain."
Heh, we've been through all this before, and nothing seems to have changed. A blindfold can "explain" why a guy doesn't see the door in front of his face, but what does it say about the existence of the door? Does the blindfold make the door objectively disappear?
You seem to have a great deal of trouble distinguishing between subjective preception and objective reality. If a psychotic sees a Viking with a bloody sword standing in front of him, but 50 other people in the room don't, is he still "right" (objectively) about the existence of the Viking. It goes without saying (it's a mere tautology) that he sees what he sees, and he's "right" in that sense. But does it reflect "reality?"
'
Philosophically, "coherent" means "internally consistent". Since SR discusses what two different observers measure, there is no incoherence. A has measurement x and y, B has measurements x' and y'. There is no inconsistency unless you add in the requirement that x = x' or y = y', but there is no reason to add this requirement."
I agree. There's nothing inherently inconsistent about two people disagreeing due to having different assumptions to begin with. It's to be expected. That's not what the twin "paradox" is about. The paradox only arises because SR claims they are BOTH right. At least one of them must be wrong. In the twin case, it is the travelling twin who is wrong when he claims the earth twin in the one aging slower. He does that because he wrongly assumes that HE is not moving.
There IS a reason not to claim that each of two clocks runs slower than the other. It's called fundamental logic, eh?
"On a more general topic, I wonder why clocks slow down in a gravitational field and with increased speed. What causes that?
The short answers is "they don't".
They don't, eh? Ever heard of the GPS? It proves they do.
"The twin paradox relies on one twin (at least) taking a non-inertial path. SR offers no answer, because SR does not apply to non-inertial paths. By contrast, GR offers the correct answer to the twin non-paradox."
Heh, we've only been through this 4 or 5 times, and you never learn. I remember when you called Essen an "idiot" and refused to read his article because he was "stupid" for thinking that SR applied to a round-trip path. When I pointed out that he was merely quoting Einstein, you basically said that Einstein was stupid too. You obviously know SR better than Al, eh? Just another case when you are incapable of questioning, or relinquishing, after having been proved wrong time an time again, your mistaken preconceptions.
Once again look up the "clock hypothesis," which is now said to be an "axiom" or SR. It has, in any event, been proven many times over in the laboratory. As far as time dilation goes, acceleration has not effect whatsover.
"GR correctly predicts the outcomes, but I'm not so sure AST does."
Only part right. Yeah, GR, which is a theory of gravity, not motion, DOES correctly predict the gravitational influence on relative time. It does NOT predict the speed effects. SR does, but it's predictions are wrong.
"Just inertial frames in a vacuum, in both SR and LR."
Wrong. You don't understand LR, that's clear. I have no idea why you think you do.
Al ratified, rather than eschewed, ignorance, in this example. He actually glorified it by making it (ignorance) mandatory for all SR observers.
"Rather, he said this particular knowledge had no effects on the measurements taken."
No, that's not what he said, not in substance, anyway. In SR it is MANDATORY that every observer (except accelerating ones) DENY that they are, or could be, in motion. There MUST be a conflict for SR to work out right. As soon as the guy on the train says he is moving, and that therefore his clock has slowed down, not the guy at rest with respect to the earth's surface, SR goes out the window. Light speed in no longer constant.
So, that kind of (lack of knowledge) is CRUCIAL to Al's theory. The astronaut launched to the moon MUST insist that he is motionless while the moon moves toward him and the earth moves away from him. How ridiculous.
"So, that kind of (lack of knowledge) is CRUCIAL to Al's theory. The astronaut launched to the moon MUST insist that he is motionless while the moon moves toward him and the earth moves away from him. How ridiculous."
By the way, Al was merely repeating what Poincare had said before him. It was not a new "insight" on Al's part. Poincare noted that you could achieve a "subjective" sense of relativity if all observers failed to acknowledge their own motion. Of course he never bought into this concept as being "true." Like Lorentz, he viewed "local time" as merely a convenient mathematical shortcut with no physical meaning whatsoever. Al decided to say that local time was "real" (objective) time. As I noted earlier, he later called this type of positivism "nonsense."
I said: "Think about it."
Let me help you. Pretend the earth was like a transparent beach ball that is rotating. If you were at the center of if it, and not rotating, you would see a "spot" (such as the Naval Obseratory in Maryland), moving east. You would see a plane flying away from that spot at the rate of 500 mph moving to the east even faster than the spot. For the same reason you would see a plane flying away (westward) from the spot as also moving east, but not as fast as the spot, and even less fast than the other plane.
This is exactly what the atomic clocks used showed (as the experiment has been repeated, with much more accuracy, many times since.
SR would say that if two clocks were flying away from the observatory at equal speeds, the time dilation for each would be identical (which is what you are saying). Unfortunately for you and SR, the experimental data proved otherwise.
There's a video on youtube where Hafele and Keating are repeating their experiment. At any given moment of their journey, they can tell you exactly how much time they are losing compared to a stationary earth clock. Lo and behold, when they land and compare their clock to the one that remained on earth, theirs shows less time elapsed.
They can ONLY do this because they know, and don't deny, as SR would require them to do, that they are moving with respect to the earth. They do not assume that the earth is moving while they remain stationary. If they did, their predictions would be completely wrong.
Of course they factor in GR effects too, but that is not germane to their calculation regarding dilation due to speed alone (SR).
I said: "So, that kind of (lack of knowledge) is CRUCIAL to Al's theory. The astronaut launched to the moon MUST insist that he is motionless while the moon moves toward him and the earth moves away from him. How ridiculous."
So, by some type of magic, when the rocket fuel ignites, the astronaut remains motionless while, suddenly, the earth is pushed away from him, and the moon is attracted him and starts approaching him accordingly, eh? Yeah, that's the ticket! That's PHYSICS, I tellya.
"The twin paradox relies on one twin (at least) taking a non-inertial path. SR offers no answer, because SR does not apply to non-inertial paths. By contrast, GR offers the correct answer to the twin non-paradox."
Mainstream science rejects Einstein's supposed GR "resolution" of the twin paradox. If they didn't have such respect for him the term would be "ridicules" rather than rejects. His invocation of a suddenly appearing fictitious gravitational field to resolve a physical problem would be viewed as the kind of magical, metaphysical hocus pocus that a "crank" would resort to.
He made it clear that he did not believe that any of the (many) other attempts to resolve the paradox were viable, and of course he was right about that, however. Hence the need for desperate measures on his part.
"On a more general topic, I wonder why clocks slow down in a gravitational field and with increased speed. What causes that?
The short answers is "they don't".
Seriously now, Eric: Are you confused? Have you stopped thinking? Are you denying the obvious out-of-hand because the facts don't square with your pet theories?
Do you have any basis whatsoever for denying that experiments like the H-K, others like them, and the GPS don't prove, as a factual matter, that clocks slow down due to speed (and speed alone, since acceleration has no direct effect on such time dilation)?
"SR does not discuss nor predict changed circumstances. It is restricted to unchanging circumstances. You were just pointing that up above its scope is so limited as to be a novelty."
Well, yes and no. Of course it tries to explain lots of "changed circustances." Like one twin changing his circumstances and heading for a distant star, for example. The "changed" circumstances of at least one (SR says two) clocks slowing down in every SR calculation, etc.
But you're right in the sense I intend the phrase (which is not how you intend it). It really makes no attempt to give any kind of physical explanation for the changes it deals with. It gives mathematical descriptions (which are not explanations) for some things. A "geometrical" explanation of SR is NOT an explanation. Changing frames of reference (an abstract concept), for example, upon "turn-around" (which, by the way, is not necessary in accelerationless twin paradox puzzles), with the supposed physical consequence of perhaps a million years "passing" suddenly for people on a distant planet, is NOT an explanation for anyone but those who ignore physics and think math IS physics (it aint).
Your very adherence to a geometrical interpretation shows that you think that math "explains" things. Only real, tangible things "out there," in the world, are capable of causing an effect. Math can never do that.
"These planes flew around the planet. They each would have flown faster and slower than the ECI during their journey, in about equal amounts. When your source makes a silly mistake about a detail and attaches importance to it, I find it unlikely to be worth my time to read the rest. You may think this hide-bound of me. I call it prudent."
You call it prudent, I call it just plain wrong (what you're saying that is). The author is correct. Have you read the HF paper? Apparently not. You often do this. You deduce indisputable "facts" from your mistaken assumptions, then say that anyone who disagrees is "silly."
Well, it was wrong to say they would have flown equal amount with respect to the ECI, because one plane did not make a complete circle with respect to the ECI, while the other would have made more than a circle.
The plane on the clock running eastward was slower, because it was going faster, and vice versa. This could not be explained by SR.
Observed from any *inertial* frame, the clock on the eastward plane runs slower. This is exactly what SR predicts.
Only an LR calculation using the ECI as the "preferred frame" correctly predicted this effect by the amount the clocks actually differed.
Think about it.
If you really want to think about it, the ECI is the "Earth-centered non-rotating inertial reference frame", which is already a fiction, because the Earth is not in an inertial frame, it is in constant acceleration.
However, if you calculate using SR from the ECI, the eastward clock runs slower.
"Since you will rarely have two distinct inertial frames each conducting their own measurements, AST offers no advantage."
What!? An AST offers the "advantage" of making the correct prediction is ALL frames, not just inertial ones, caincha see?
To use the AST, you have to calculate from an inertial frame, just like with SR. AST only allows one frame to be used, SR allows any inertial frame.
"It explains why you get a different measurement for the amount of surface area you can see. That's all I need it to explain."
Heh, we've been through all this before, and nothing seems to have changed. A blindfold can "explain" why a guy doesn't see the door in front of his face, but what does it say about the existence of the door? Does the blindfold make the door objectively disappear?
No.
You seem to have a great deal of trouble distinguishing between subjective preception and objective reality. If a psychotic sees a Viking with a bloody sword standing in front of him, but 50 other people in the room don't, is he still "right" (objectively) about the existence of the Viking. It goes without saying (it's a mere tautology) that he sees what he sees, and he's "right" in that sense. But does it reflect "reality?"
The only way I can sensibly interpret your paragraph is to being saying that the results of a measurement process are just as subjective and ephemeral as a hallucination, and do not have a coherent physical meaning. If that is indeed your position, than by that definition SR does not discuss anything with a coherent physical meaning. However, that position has additional consequences that you don't seem willing to accept.
Philosophically, "coherent" means "internally consistent". Since SR discusses what two different observers measure, there is no incoherence. A has measurement x and y, B has measurements x' and y'. There is no inconsistency unless you add in the requirement that x = x' or y = y', but there is no reason to add this requirement."
I agree. There's nothing inherently inconsistent about two people disagreeing due to having different assumptions to begin with. It's to be expected. That's not what the twin "paradox" is about. The paradox only arises because SR claims they are BOTH right. At least one of them must be wrong. In the twin case, it is the travelling twin who is wrong when he claims the earth twin in the one aging slower. He does that because he wrongly assumes that HE is not moving.
In order to say he is not moving, the spaceship twin has to invoke immense surges of pseudo-gravity to explain the behavior of the planetary twin, and the time contraction effects of the acceleration used to counter this gravity (as derived from GR) mean the the planetary twin still comes out younger.
There IS a reason not to claim that each of two clocks runs slower than the other. It's called fundamental logic, eh?
Right. They both run at the same rate.
"On a more general topic, I wonder why clocks slow down in a gravitational field and with increased speed. What causes that?
The short answers is "they don't".
They don't, eh? Ever heard of the GPS? It proves they do.
The effect is called "time dilation", not "clock impedence". The need to adjust clocks only proves there is a difference in the times they read. It does not prove one clock is slower.
"The twin paradox relies on one twin (at least) taking a non-inertial path. SR offers no answer, because SR does not apply to non-inertial paths. By contrast, GR offers the correct answer to the twin non-paradox."
Heh, we've only been through this 4 or 5 times, and you never learn.
I remembered it badly. SR does actually provide the correct solution to the twin "paradox" as long as you calculate it from any inertial frame.
Just another case when you are incapable of questioning, or relinquishing, after having been proved wrong time an time again, your mistaken preconceptions.
We each have our bad habits on this topic.
As far as time dilation goes, acceleration has not effect whatsover.
This is one of your errors. Acceleration causes time contraction.
"GR correctly predicts the outcomes, but I'm not so sure AST does."
Only part right. Yeah, GR, which is a theory of gravity, not motion, DOES correctly predict the gravitational influence on relative time. It does NOT predict the speed effects. SR does, but it's predictions are wrong.
Since SR is a subset of GR, not a separate thing, your position here makes zero sense.
Also, GR is not a "theory of gravity", but a theory of the effects of gravity on objects.
"Just inertial frames in a vacuum, in both SR and LR."
Wrong. You don't understand LR, that's clear. I have no idea why you think you do.
In your LR/AST, there is only one true frame of reference, and the speed of anything needs to be measured in reference to that frame. The speed of light is a constant in LR.
Now, perhaps you meant "the difference between the speed of light and the speed of a moving object", but you did not say that.
No, that's not what he said, not in substance, anyway. In SR it is MANDATORY that every observer (except accelerating ones) DENY that they are, or could be, in motion.
No, it's not mandatory at all. You can always make measurements under the assumption you are moving at any speed under c, than adjust those measurements match the frame you are assuming is motionless. You confuse permission with requirement.
Under any understanding of relativity (SR, LR, AST, pick-your-poison), what you can't do is find experimental evidence within your environment that your inertial frame is in motion. You are nonetheless allowed to assume it is.
There MUST be a conflict for SR to work out right. As soon as the guy on the train says he is moving, and that therefore his clock has slowed down, not the guy at rest with respect to the earth's surface, SR goes out the window. Light speed in no longer constant.
Completely, totally incorrect. Once you choose an inertial frame as the non-moving speed, you will always calculate light to be moving at c in that frame. In that frame which you are not in, the difference in speed between light and you will not be c, but light will still move at c in the frame you have chosen.
So, that kind of (lack of knowledge) is CRUCIAL to Al's theory. The astronaut launched to the moon MUST insist that he is motionless while the moon moves toward him and the earth moves away from him. How ridiculous.
Yes, your twisting of SR is completely ridiculous.
Al decided to say that local time was "real" (objective) time. As I noted earlier, he later called this type of positivism "nonsense."
Perhaps he only meant that the ridiculous interpretations of his theory were nonsense.
SR would say that if two clocks were flying away from the observatory at equal speeds, the time dilation for each would be identical (which is what you are saying). Unfortunately for you and SR, the experimental data proved otherwise.
In SR, the observatory is under acceleration, and has no inertial point of view. SR only makes calculations from an inertial point of view, and is not capable of making calculations from the point of view of the observatory.
So, by some type of magic, when the rocket fuel ignites, the astronaut remains motionless while, suddenly, the earth is pushed away from him, and the moon is attracted him and starts approaching him accordingly, eh? Yeah, that's the ticket! That's PHYSICS, I tellya.
Any time you treat an accelerated frame as an inertial frame, the results are nonsense.
His invocation of a suddenly appearing fictitious gravitational field to resolve a physical problem would be viewed as the kind of magical, metaphysical hocus pocus that a "crank" would resort to.
A fictitious gravitational field for a fictitious change from an accelerated viewpoint to an inertial one. So, this is explaining one fiction using another.
He made it clear that he did not believe that any of the (many) other attempts to resolve the paradox were viable, and of course he was right about that, however. Hence the need for desperate measures on his part.
He responded desperately to a fiction?
"On a more general topic, I wonder why clocks slow down in a gravitational field and with increased speed. What causes that?
The short answers is "they don't".
Seriously now, Eric: Are you confused? Have you stopped thinking? Are you denying the obvious out-of-hand because the facts don't square with your pet theories?
The facts square just fine with my understanding of the theory.
Do you have any basis whatsoever for denying that experiments like the H-K, others like them, and the GPS don't prove, as a factual matter, that clocks slow down due to speed (and speed alone, since acceleration has no direct effect on such time dilation)?
Your question has so many false assumptions, it's hard to unpack this into a simple answer. I don't deny the observations from the H-K experiments or the GPS numbers (although, above, *you* claim that measurement is just as subjective as a hallucination of a Viking, from what I can tell, so I'm not sure why you are so insistent that it is a real thing here). Clocks don't slow down. Time contracts for objects under acceleration, like those on the surface of a planet or (to a lesser degree) in planetary orbit.
"SR does not discuss nor predict changed circumstances. It is restricted to unchanging circumstances. You were just pointing that up above its scope is so limited as to be a novelty."
Well, yes and no. Of course it tries to explain lots of "changed circustances." Like one twin changing his circumstances and heading for a distant star, for example. The "changed" circumstances of at least one (SR says two) clocks slowing down in every SR calculation, etc.
SR doesn't have any clocks slowing down.
Your very adherence to a geometrical interpretation shows that you think that math "explains" things. Only real, tangible things "out there," in the world, are capable of causing an effect. Math can never do that.
Are distance and time real, tangible things? Or, are you saying distance and time can never cause an effect? Is there a physical reason that Olympic 1500-meter runners take longer get to the finish line that 400-meter runners not interior to the runner's bodies?
"Observed from any *inertial* frame, the clock on the eastward plane runs slower. This is exactly what SR predicts."
Wrong, according to SR, from the frame of the inertially moving eastward plane itself (for just one example), the Naval Station clock has slowed (because it is supposedly moving away from that plane), and, for the same reason, the westward-bound clock has slowed even more.
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"In order to say he is not moving, the spaceship twin has to invoke immense surges of pseudo-gravity to explain the behavior of the planetary twin, and the time contraction effects of the acceleration used to counter this gravity (as derived from GR) mean the the planetary twin still comes out younger."
You said it, "PSEUDO-gravity." Nobody buys that ridiculous argument any more (well, except for you, maybe).
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"If you really want to think about it, the ECI is the "Earth-centered non-rotating inertial reference frame", which is already a fiction, because the Earth is not in an inertial frame, it is in constant acceleration."
It is in free-fall, just like everything else it is a standard for (the ECEF and the satellites). According to the GPS experts, this free-fall is the equivalent of an inertial frame. Think about this, eh? The GPS WORKS to a marvelous degree of accuracy. And, again, reseach the clock hypothesis--acceleration has no effect on time dilation.
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There IS a reason not to claim that each of two clocks runs slower than the other. It's called fundamental logic, eh?
"Right. They both run at the same rate."
Wrong. Even if you use the ridiculous GR argument, they do NOT run at the same rate. That's the whole point of the argument--to try to explain WHY they don't run at the same rate.
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"The effect is called "time dilation", not "clock impedence". The need to adjust clocks only proves there is a difference in the times they read. It does not prove one clock is slower."
What!? Are you aware of how clocks (any clock, including pendulum clocks, hour glasses, etc.) operate? A clock doesn't "think" or act according to metaphysical dictates. It is a completely mechanical operation. Maybe the H-K experiment makes it clearer to you that all atomic clocks slow down when in motion---some more than others, depending on their speed. The frequency of the oscillations which the clock uses to mark time slow down. That's the only reason the clocks don't read the same.
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"This is one of your errors. Acceleration causes time contraction."
NO, it does not. That's exactly what the SR axiom called the clock hypothesis tells you. Accelertion, as such, has NO effect on time dilation. Only the instantaneous speed does is this (non-GR) context. Acceleration may cause an increase in speed, sure, but it does not clause time dilation.
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GR, which is a theory of gravity, not motion, DOES correctly predict the gravitational influence on relative time. It does NOT predict the speed effects. SR does, but it's predictions are wrong.
'Since SR is a subset of GR, not a separate thing, your position here makes zero sense.
Also, GR is not a "theory of gravity", but a theory of the effects of gravity on objects."
Gravity has it's own separate effect, as the GPS engineers know well. Don't confuse the two. It's proven every day by the GPS that gravity is not the only thing that affects clocks, and time dilation due to speed cannot be reduced to time dilation due to gravity. SR has no satisfactory physical explanation for the twin paradox. So, even assuming that one is a "subset" of the other (I don't agree in the least with that, but...), then they both fail to explain it equally. Figures, sho nuff.
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"The speed of light is a constant in LR."
Well, it is isotropic in only one frame--the established preferred frame (and frames which shares that state). In other frames, light does not travel the same regardless of direction, so it is NOT constant in that respect--just as the H-K experiment showed. Furthermore, an AST does NOT posit the speed of light as one that can't be exceeded.
"No, it's not mandatory at all. You can always make measurements under the assumption you are moving at any speed under c, than adjust those measurements match the frame you are assuming is motionless. You confuse permission with requirement."
No, this is wrong. Check it out with any physicist who knows what he's talking about. I could cite you to a Harvard physics professor, it you need it, but you shouldn't, really. Just think about it. There MUST be a disagreement between any two relatively moving parties about who is moving for the math to work out according to SR dictates. If they ever agree, then you're right back to an AST theory. The guy on the train MUST say he is motionless, and that all things affixed to the earth are moving.
Sure, SR sucks you in by first saying there is no reason to prefer one frame over another, which sounds reasonable enough. But, then it tells you (without admitting it) that there is ALWAYS a preferred frame, which you MUST use to comply with SR. That preferred frame is always the one YOU are in. Anything in the universe that is moving relative to YOU, whether it's moving one inch per century or at .99 C, is MOVING. You are NOT. You are the ether is all SR calculations. It is always the MOVING clock that runs slow. In SR, that is always, and must always be, the other guy's clock, never yours.
Think about it, eh? That's why the guy on a moving train will ask the conductor if Chicago stops here, ya know? That's why the twin paradox arises. But the travelling twin is FORCED to claim that the earth's clock is slow. If he wasn't, and admitted he was the one moving, they would be in perfect agreement--he is aging less slowly, because he is the one moving. That's what LR would say, and that's what a traveller subscribing to LR would conclude. At it IS the case, that his clock slows down, not the earth's. SR is forced to admit this. That's why it needs to explain (but can't) why it's theory says that each clock runs slower than the other.
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"Completely, totally incorrect. Once you choose an inertial frame as the non-moving speed, you will always calculate light to be moving at c in that frame. In that frame which you are not in, the difference in speed between light and you will not be c, but light will still move at c in the frame you have chosen."
What? If I'm reading to correctly, you are saying exactly what I'm saying (and LR says). So how am I "totally incorrect?"
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"Under any understanding of relativity (SR, LR, AST, pick-your-poison), what you can't do is find experimental evidence within your environment that your inertial frame is in motion."
What in the hell do you mean by "within your enviroment?" Is the the windowless cabin envirnoment, which you're trying to make exclusive? Look out the window, fool.
Or ask the recent Nobel-prize winner for his CMB work, George Smoot, who says the CMB is a "cosmic rest frame" which you can use to determine the earth's (and the entire galaxy's for that matter) speed and direction through space. Smoot, by the way, says this does not conflict with SR, because SR does not hold that there is no "ether." They just didn't know how to detect it in Einstein's day.
"In SR, the observatory is under acceleration, and has no inertial point of view. SR only makes calculations from an inertial point of view, and is not capable of making calculations from the point of view of the observatory."
Physics is capable of making such observations, and that is acknowledged by physicists in the SR context. They will tell you that, even in SR (which acknowledges that acceleration is absolute), it is not always the "other guy's" clock which runs slow. When one is accelerating, BOTH parties will say the non-accelerating clock is running slower (which is exactly what LR would say). Physicists just revert to LR principles of understanding in such cases.
You want to keep insisting that SR "just doesn't apply," even when any difference is beyond measurement accuracy. Your "go to" response to any inconsistency is that SR "doesn't apply." Would you also agree then that none of the many terrestrial experiments which adherents claim "confirm" SR in fact say ANYTHING about SR? You don't seem to.
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Again: "In SR, the observatory is under acceleration, and has no inertial point of view. SR only makes calculations from an inertial point of view, and is not capable of making calculations from the point of view of the observatory."
Guess what? LR IS capable of making (completely accurate) predictions in those circumstances. The H-K experiment proves that.
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"you* claim that measurement is just as subjective as a hallucination of a Viking, " Heh, I made no such claim about measurement in general. As always, you completely miss the point. And that point is simple--perception is not objective reality. Any given perception, or measurement, can be mistaken because of a misunderstanding of objective reality. I say can be, not must be.
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"clocks don't slow down. Time contracts for objects under acceleration, like those on the surface of a planet or (to a lesser degree) in planetary orbit."
You don't seem to realize how ass-backwards this claim is. Tell me, what is "time," exactly? It is a thing that makes clocks mechanically malfunction? Does "time" reach into clocks and make their readings change? Do you think clocks measure "time" an as abstract entity? They don't. They simply make recurring motions and then WE (not time) use that knowledge to mark the duration of a minute, an hour, or whatever. Freeze a clock and it will slow down. "Time" didn't make it slow down, physically changed circumstances did that. They have slowed the speed of light to 35 mph in temperatures near absolute zero. Do you think "time" made light go slower, too?
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"SR doesn't have any clocks slowing down." Just keep telling yourself this. Hogg (and just about any other physicist, including Al himself) will tell you that these changes are actual, objective ones, not just "apparent." The experimental facts tell you otherwise, but don't let that stop your idiosyncratic metaphysics, eh?
"Or, are you saying distance and time can never cause an effect? Is there a physical reason that Olympic 1500-meter runners take longer get to the finish line that 400-meter runners not interior to the runner's bodies?"
As usual, you seem to take any remote kind of correlation as the equivalent of a cause. If a runner can only run 10 mph, tops, then that is because of a lot of physical factors. His anatomy (heart condition, metabolism, leg muscles, etc.), for example. And the conditions he's running in--the humidity, the incline of the surface he's running on, snow or mud, the wind, etc.
If he can only run 10 miles per HOUR, it's not "caused by" either the distance (10 miles) or the time (one hour). Who would ever think that? Sure, he can't run to the moon in 10 seconds flat, but who would say the distance "causes" that. Numbers are not causes, sorry. They are, at best, descriptive conveniences.
Edit: I said; "BOTH parties will say the non-accelerating clock is running slower (which is exactly what LR would say)."
I meant "running faster," not slower.
"No, it's not mandatory at all. You can always make measurements under the assumption you are moving at any speed under c, than adjust those measurements match the frame you are assuming is motionless. You confuse permission with requirement."
Heh, coming back to this mistaken claim, it reminds me of the time we were arguing about how Jill would "view" (deduce is the proper word here, not view) Jack's clock if she admitted she was the one moving (as was postulated in the example being considered).
The physicist from Jazzfans (forgot his name) said it would be the same either way. Obviously wrong.
I then went to a physics forum, and, after much discussion (and initial misdirection and equivocation from the relativists there) it was finally admitted that the figures I gave were, in fact, on the minkowski chart BUT that SR would not permit that viewpoint. Nothing in "reality" prevented her from being the one moving (as postulated) but the mathematical "protocols" of SR prohibited that point of view. Which is just a roundabout way of saying that SR mandates that the frame that YOU are in must be deemed to be motionless.
Even so Colton (is that it? it just kinda came to me) was simply wrong in saying that Jill would see Jack's clock as reading the same whether he or she were actually moving. The simplest reflection will tell you that. The LT says the moving clock will run slow. If you are moving (faster) that will be your clock. If he is moving, his will be the slow clock, and yours will be faster, not slower. Using the LT, they could not possibly be the "same either way." The LT does NOT, itself, say that each clock runs slower than the other. As Hogg acknowledged, if one is running slower, then the other must be running faster. John can't be taller than Jim while Jim is taller than John. Any schoolboy can tell you that.
Just another obvious contradiction that relativists never seem to recognize. They will say things like "if they are walking away from the other, then each will see the other as shorter." Heh, how specious. "Appearance" is not reality. The question is, who is taller when they are standing next to each other? THAT will not change, no matter how much they separate and regardless of perceptual illusions. They don't ACTUALLY each get shorter as they separate. But that is the kind of fact that you will routinely deny (or overlook, whatever).
I said: " Do you think clocks measure "time" an as abstract entity? They don't."
To elaborate, if a wristwatch is miscalibrated so that it runs slow by 5 minutes per hour, is that because "time" changed and it always measures "time?" If 10 wrist watches all give you a different reading, is that because "time" changed in 10 different ways, one for each of them? How in the world could abstract "time" (whatever you think that is) affect the mechanicals workings of a clock? Does it use a sledge hammer? Tweezers? What?
I already know that you can't even understand the question. So, I'll answer it myself. A clock only slows down (or speeds up) because it's internal "regular durations" have changed. A grandfather clock (or a wristwatch) will slow down, then stop, if you don't keep it wound up. But that is not because "time" has changed, it it? There is a physical, not a metaphysical, explanation for it. Mechanical clocks cannot possibly measure "time," per se.
You said it, "PSEUDO-gravity." Nobody buys that ridiculous argument any more (well, except for you, maybe).
Interesting that you interpret the use of "pseudo" to indicate I might believe something is real. It speaks volumes of you.
Before discussing SR/GR further, I would like to focus on a particular issue.
If he can only run 10 miles per HOUR, it's not "caused by" either the distance (10 miles) or the time (one hour). Who would ever think that? Sure, he can't run to the moon in 10 seconds flat, but who would say the distance "causes" that.
If distance is not a real, physical phenomenon (regardless of whether it is a "cause" or not, whatever that means), why can't he run from New York, NY to Los Angeles, CA in 10 minutes? Some unreal notion? Some non-physical notion?
And that point is simple--perception is not objective reality. Any given perception, or measurement, can be mistaken because of a misunderstanding of objective reality. I say can be, not must be.
Mistaken in the manner of seeing a hallucination, or mistaken in a systemic, predictable manner? If the measurements from a given perspective do not match the measurements from a different (supposedly more correct) perspective, are they therefore hallucinations?
Are length and time real phenomena? Are they physical (not necessarily meaning material)? Are they merely subjective and perspective?
"Before discussing SR/GR further, I would like to focus on a particular issue."
Ok, sure.
"If distance is not a real, physical phenomenon (regardless of whether it is a "cause" or not, whatever that means), why can't he run from New York, NY to Los Angeles, CA in 10 minutes? Some unreal notion? Some non-physical notion?"
You say: "(regardless of whether it is a "cause" or not, whatever that means),..."
I as went to elaborate lengths to explain, I am talking about the plausibility of causal explanations, NOT whether x or y "exists." You keep trying to talk about a different topic, all while acting like it's the same topic. It aint.
With that understanding I will give my answer to your question. Distance in a concept, a mental construct. That doesn't mean it isn't "real," but it does mean it's not a physical object which exists in three dimensions, like a rock, for example. It is "real" in a different, mental way. In my opinion, and that of any realist, mental concepts do not, and cannot, "cause" effects in the objective world. The 100 yard distance between two goalposts on a football field can be measured. The fact that they are separated by space is true. We will commonly call the gap between them "space," and the measure (not cause) of that space "distance." "Space" too is just a mental concept. It's not something tangible that you can go out and have a beer with.
But it's ridiculous to claim that distance "actually" changes with speed. If 5 different observers are flying over a football field at different speeds, the goalposts do NOT suddenly move in multiple ways and "set themselves up" 5 different distances apart just because different observers might (subjectively) "see" them that way. It is ALWAYS the same distance unless the goalposts ARE actually moving with respect to each other. You can measure that distance in an infinite number of ways if your measuring rods are miscalibrated, but it will STILL always be the same distance. Measuring it differently CANNOT change that.
I hope that serves to answer this question also: "If the measurements from a given perspective do not match the measurements from a different (supposedly more correct) perspective, are they therefore hallucinations?"
No, not "hallucinations" at all. Just mismeasurements, based on mistaken assumptions. Each of the 5 observers can insist that "his" yardstick is right, but simple logic tells you that at least 4 of them MUST be wrong. I mean, let's just stipulate than one yardstick is .98 yards, one .99 yards, one 1.00 yards, one 1.01 yards, and the last is 1.02 yards. Then one of them is right, all the others wrong. Not because anyone was "halluncinating," but simply because they mistakenly assumed their yardstick was accurate in 4 of the 5 cases.
I trust that what I've said so far answers this question also: "Are length and time real phenomena? Are they physical (not necessarily meaning material)? Are they merely subjective and perspective?"
They are not "merely" subjective, but they certainly have a subjective aspect to them--time especially. You can set two posts 100 yards apart and keep them stationary for repeated measurements indefinitely, but you cannot "freeze" time. You can't physically measure time with a 3 dimensional yardstick as you can with length. The process of establishing measurable durations of time is deductive, based on ultimately unprovable assumptions.
You also asked "..., why can't he run from New York, NY to Los Angeles, CA in 10 minutes?Some unreal notion? Some non-physical notion?"
No, for the reasons I mentioned to begin with, which are strictly physical reasons. The "metaphysical" notion I was speaking of was your presumptions that clocks measure abstract "time," and that "time" (not mechanical gears, or whatever) is what directly causes them to run faster or slower. Time does not "stop" when a wristwatch runs down and quits moving altogether. That's obvious, isn't it?
Newton on "time:"
Relative time is time measured relative to some perceptible motion. E.g., we measure time by clocks or by motions of heavenly bodies (sun, stars). Measures of relative time may not be accurate. A clock can
run fast or slow. The heavenly bodies don’t move with exactly constant speeds. What we are trying to measure by these means is absolute time. It “flows uniformly.” But we can’t perceive absolute
time directly, which is why we use relative time.
http://patrick.maher1.net/317/lectures/newton1.pdf
Newton makes the same kind of distinctions (between "relative," sensibily measuremened aspects of time and the unchanging concept itself, which he calls absolute time) with respect to both space and motion, too, as these lecture notes show.
Some positivists refuse to acknowledge any such distinctions. Of course their philosophy of science has been throughly refuted, mainly because it is self-refuting.
Al once since said, in a positivistic vein, that "time is what a clock measures," with the implication being that time simply IS whatever a clock measures. This is an inherently ridiculous notion and Al later noted when he said that a good joke should not be repeated too often.
Distance in a concept, a mental construct. That doesn't mean it isn't "real," but it does mean it's not a physical object which exists in three dimensions, like a rock, for example. It is "real" in a different, mental way.
But it's ridiculous to claim that distance "actually" changes with speed.
If distance is a mental concept, why is it ridiculous that it would change with speed? Many other mental concepts would change with speed.
Does a length between two goalposts exist even if there is no mind to see it? If so, how is it a mental concept, when it exists without a mind?
You can set two posts 100 yards apart and keep them stationary for repeated measurements indefinitely, but you cannot "freeze" time.
You can measure the same time interval with different clocks, correct?
I agree you can't measure time with a yardstick any more than you can measure distance with a clock.
The "metaphysical" notion I was speaking of was your presumptions that clocks measure abstract "time," and that "time" (not mechanical gears, or whatever) is what directly causes them to run faster or slower.
That's not my position.
Each of the 5 observers can insist that "his" yardstick is right, but simple logic tells you that at least 4 of them MUST be wrong. I mean, let's just stipulate than one yardstick is .98 yards, one .99 yards, one 1.00 yards, one 1.01 yards, and the last is 1.02 yards. Then one of them is right, all the others wrong.
If length is a mental construct, how can any yardstick be classified as right or wrong?
"If distance is a mental concept, why is it ridiculous that it would change with speed? Many other mental concepts would change with speed."
Read what Newton said (or Plato, if you prefer). Such concepts are, by their very nature, immutable and unchanging in theory. They are "abolute" to use Newton's terms, not relative. Practical obstacles to "measuring" them do NOT change the concept.
Tell me what you have in mind when referring to a "mental concept" that changes with speed.
"If distance is a mental concept, why is it ridiculous that it would change with speed? Many other mental concepts would change with speed."
I asked you a question about this, but the question misses the point, in any event.
Unless the goalposts are ACTUALLY moving with respect to the other, the distance between them cannot physically change. That is implicit in the very concept of distance. Changing your concept would not have any effect on the objective world in any event, which was the original point.
Concepts are what we invent and utilize to aid us in understanding the objective world, but they are not the objective world themselves. They are akin to what Kant called "catagories of understanding."
You tell me: Suppose you had a measuring stick that was 18 inches long, but you were somehow under the impression that is was 36 inches long. Using it, you measure a football field to be two hundreds yards long.
Does that "make" it 200 yards long? If I measure it with a standard yardstick and conclude that it is one hundred yards long, does that mean I have measured a different "distance?" Are both measurements "right" as a matter of objective reality?
Does the distance change? Yes or no? If you say "yes," then you obviously don't understand the concept, which is objective, not subjective.
From Wiki:
"Contemporary philosophical realism is the belief that some aspects of reality are ontologically independent of our conceptual schemes, perceptions, linguistic practices, beliefs, etc....as opposed to skepticism and solipsism."
https://en.wikipedia.org/wiki/Philosophical_realism
To quote Al on the topic again:
"We represent the sense-impressions as conditioned by an “objective” and by a “subjective” factor. For this conceptual distinction there also is no logical-philosophical justification. But if we reject it, we cannot escape solipsism. It is also the presupposition of every kind of physical thinking...."
The presumption of realism underlies every kind of physical thinking. If you're a solipsist, then nothing exists except in your mind.
Which are you? Do you think that "some aspects of reality are ontologically independent of our conceptual schemes, perceptions, linguistic practices, beliefs," or do you think that NOTHING exists or is true unless YOU think it does/is?
If the latter, then you should never try to talk about physics. There is no such thing from that perspective.
For what it's worth, I disagree with Al about this statement: "For this conceptual distinction there also is no logical-philosophical justification."
If all he means is that there is no ultimate proof that there is a distinction between objective reality and subjective perception, then I agree.
But I don't agree that there is no logical-philosophical JUSTIFICATION, for thinking there is a distinction. Such a belief is not only "justified" (even if not absolutely proven) by our experience, but it is virtually mandated, in my opinion.
The "metaphysical" notion I was speaking of was your presumptions that clocks measure abstract "time," and that "time" (not mechanical gears, or whatever) is what directly causes them to run faster or slower.
That's not my position.
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Really? You always want to take both sides of contradictory conclusions, it seems.
First you say: "I don't deny the observations from the H-K experiments or the GPS numbers." OK, fine, the observations are that clocks do, in fact, slow down with increased speed (and certainly not "reciprocally).
But then you contradict yourself by saying:
Clocks don't slow down. Time contracts for objects under acceleration..." Well, which is it that you actually subscribe to? The observations in the foregoing experiments, or your metaphysical postulation that "clocks don't slow down?" You say "time contracts," as amorphous as that claim is. What does that mean? Clocks don't slow down, but "time" does? You can't see either the contradictions or the implications of your claims?
As you have said more explicitly in the past, TIME slows down, NOT clocks. Well, then, if that's true, then clocks would change in the least (contrary to what is actually observed).
Or, as I put it (and as you have yourself on other occasions) you think "time" causes the clocks to have different readings. Time controls the clocks somehow. Clocks are therefore like loyal, cognizant creatures than understand and obey the commands of their ruler, "Time," not physical laws of mechanics. They change only when "time" tells them to.
Edit: I meant to say " Well, then, if that's true, then clocks would NOT change in the least (contrary to what is actually observed).
"I agree you can't measure time with a yardstick any more than you can measure distance with a clock."
I'm glad to hear you agree that you can't measure distance with a clock. SR thinks you can. Since speed equals distance/time, it would perhaps seem, at first blush, that you can deduce the measurement of any of the 3 terms (S, D, and T) if you already know 2 of the 3. If, for example, you already know the RATE of speed, and the distance traversed at that rate, the amount of time elapsed would follow as a matter of mathematics.
But the problem with what SR does is that, as an empirical matter, you CAN'T know the rate of speed unless you ALREADY know the time and distance (which are the necessary elements needed to ascertain rate of speed in the first place). There is no way to say that you can "deduce" the amount of time elapsed without already knowing it. You can't "deduce" it mathematically. You must FIRST measure BOTH the time elapsed and the distance traveled BEFORE you can have the knowledge required to determine what the rate of speed is.
You said: "However, if you calculate using SR from the ECI, the eastward clock runs slower."
You prove the point I made earlier, which is that many call LR SR, and then say SR has been confirmed. You are not "using SR," if and when you posit the ECI as the preferred frame which is the ONLY one that gives correct predictions. If and when you do that, you are using LR, not SR.
If you are "using SR" from any OTHER frame of reference, then it's predictions are incorrect. The H-K observations are only consistent with the notion of absolute simultaneity, not relative simultaneity. In order to correctly calculate the observed differences in clock readings, you must synchronize ALL clocks to the "master" clock at the ECI.
Some of your claims cumulated:
1. "There IS a reason not to claim that each of two clocks runs slower than the other. It's called fundamental logic, eh?
Right. They both run at the same rate
They "run at the same rate," eh?
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2. "SR doesn't have any clocks slowing down."
You disagree with Hogg and other distinguished physicists about this, but but let's leave that be. You are free to deny the facts claimed by others, whether you do so consistently, or not. I just want to look at YOUR claims here.
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3. "clocks don't slow down. Time contracts for objects under acceleration" I thought we were talking about SR here, and you (in)consistently (and incorrectly) claim that SR can make no calculations for accelerating objects. But let's leave that aside, for now. Your claims is that clocks DON'T slow down, but rather that "time" contracts.
I've already pointed out that the clocks DON'T run at the same rate, and that neither SR nor GR claim they do. Yet you somehow think your mistake in consistent with both SR and GR, or GR, but not SR, according to some of your claims.
If there were no difference in clock rates, the LT would be totally unnecessary, unwarranted, and inapplicable for questions of motion. Simple Galilean transformations would answer all questions. Yet you ratify the need for the LT. The LT PRESUMES a difference in clock rates. If there were no difference then all clocks would agree everywhere. You would have absolute simultaneity without any need for "adjustments" between frames.
But my real question here is this: Just what do you think you are saying when you say "time contracts" while clock "don't slow down?" I have tried to give this inherently contradictory claim some semblance of meaning by assuming you are trying to say something like" "Even though clocks in inertial frames moving relative to each other do, IN FACT, record different amounts of time elapsed, it is NOT because of ANY internal change in the rates at which they tick. It is only because the rate at which they tick is irrelevant, and the clocks obey the dictates of time, even when they tick at the same rate."
The way I put it makes no sense, either, not to me at least. But apparently you think it is quite sensible. How, in your words, do you get different readings from clocks which tick at the same rate?
Coming back to this for a minute:
2. "SR doesn't have any clocks slowing down."
How can you even begin to think that SR, and the LT, DOESN'T hold that clocks slow down with speed? NO one thinks that. It's incomprehensible how you can claim to "know" SR and say that. If clocks didn't change with speed, then there's no "problem" for SR to attempt to solve. Time would be the same everywhere, irrespective of relative motion, just as Newton supposed.
I get the feeling that you were taught SR by some professor with half-baked ideas and a poor understanding the overall implications SR, and that you have never critically analyzed the "right answers" you memorized to pass the course.
If the reason why observers supposedly mistakenly "think" that clock rates have changed was simply because of a different perspective causing an illusory perception, who would even care (except maybe psychologists)? The subject matter of physics is not subjective perception. If clocks didn't change at all with speed, then there would be nothing for physics to even pay any attention to in the first place.
If distance is a mental concept, why is it ridiculous that it would change with speed? Many other mental concepts would change with speed."
Read what Newton said (or Plato, if you prefer). Such concepts are, by their very nature, immutable and unchanging in theory. They are "abolute" to use Newton's terms, not relative. Practical obstacles to "measuring" them do NOT change the concept.
To Newton, distance and time are not just mental concepts, they have a physical (immaterial) reality. In fact, you are the only person I can recall denying that distance and time exist outside of our minds; the only one who needs to put the scare-quotes around real. The notion of an immutable mental concept seems almost self-contradictory to me.
Tell me what you have in mind when referring to a "mental concept" that changes with speed.
You ever look at the tracks on the other side of the Metrolink? When the train is running 30 mph or so, their picture changes, and all the ties and spaces between them blend into a single surface. Your picture of the track alters with speed. The ties themselves don't blend, but then, the ties themselves have a physical reality, unchanging in the short term.
Unless the goalposts are ACTUALLY moving with respect to the other, the distance between them cannot physically change. That is implicit in the very concept of distance. Changing your concept would not have any effect on the objective world in any event, which was the original point.
If distance is just a mental concept, with no physical reality, then "the distance between them cannot physically change" is a void statement. It's like saying the beauty in a sunrise can't physically change. If distance is just a mental concept, it can mentally change, according to the mind of the particular concept bearer.
Concepts are what we invent and utilize to aid us in understanding the objective world, but they are not the objective world themselves. They are akin to what Kant called "catagories of understanding."
I agree. For example, if you called a particular unit of measurement, such as a "yard", a mental concept, and said we use it to measure and understand the objective, physical notion of distance, I would agree completely, just as I would agree that the measurement of "ounce" is a mental concept, even though the mass measured is real.
Since yard is a mental concept, everyone has a slightly different idea on what a yard looks like, absent some standard that we can measure against. If you offer four unmarked sticks of 34, 35, 36, and 37 inches to ten different people, do you think all ten will choose the same stick as being a yard long? Similarly, depending on mood and activity and absent a standard, we can different concepts for how much time has passed.
Since we agree on what a concept is, let's return to where we seem to disagree. If distance and time are mental concepts, why can't people see them differently, just as different people interpret different sticks to be yards?
You tell me: Suppose you had a measuring stick that was 18 inches long, but you were somehow under the impression that is was 36 inches long. Using it, you measure a football field to be two hundreds yards long.
Does that "make" it 200 yards long? If I measure it with a standard yardstick and conclude that it is one hundred yards long, does that mean I have measured a different "distance?" Are both measurements "right" as a matter of objective reality?
So, distance is just a mental concept which can only be "real" as opposed to real, but the notion of a "yard", designed to measure this concept of distance, converts what was a mental concept of distance into an objective reality?
Is the measurement process what takes it from "real" to objectively real? If not, how does that transformation occur?
However, since you asked me to tell you my answer, my answer is that the distance, being a real thing, is not altered by calling it two different numbers (an abstract concept) of different measurements (another abstract concept) which happen to have the same name (another abstract concept). My answer is that what is objective and physical is the distance itself, and not any measurement we apply to it.
Does the distance change? Yes or no? If you say "yes," then you obviously don't understand the concept, which is objective, not subjective.
If distance is just a mental concept to you, then you need to justify why it can't change. It's not a problem for me, because distance is not a mental concept to me.
Which are you? Do you think that "some aspects of reality are ontologically independent of our conceptual schemes, perceptions, linguistic practices, beliefs," or do you think that NOTHING exists or is true unless YOU think it does/is?
This is amusing to me, since I accept objective realities (distance and time) you have claimed to deny.
t's not my position.
====
Really? You always want to take both sides of contradictory conclusions, it seems.
Actually, it's taking neither side of those conclusions.
First you say: "I don't deny the observations from the H-K experiments or the GPS numbers." OK, fine, the observations are that clocks do, in fact, slow down with increased speed (and certainly not "reciprocally).
All the experiments show is that the clocks went through fewer ticks (or whatever else they used to measure time). To say "clocks do, in fact, slow down" is an (ontological) interpretation of the (epistemological) measurement of their having gone through fewer ticks. I have a different ontological interpretation. I have discussed my interpretation before, and for now, it seems fruitless to do so again, because my interpretation depends upon accepting something as a reality that you deny is real. So, for now, I declining to discuss my interpretation in further detail. I expect that you will nonetheless rant on about what you consider my interpretation to be.
But then you contradict yourself by saying:
There is no contradiction.
You say "time contracts," as amorphous as that claim is. What does that mean?
We'll come back to that.
You said: "However, if you calculate using SR from the ECI, the eastward clock runs slower."
You prove the point I made earlier, which is that many call LR SR, and then say SR has been confirmed. You are not "using SR," if and when you posit the ECI as the preferred frame which is the ONLY one that gives correct predictions. If and when you do that, you are using LR, not SR.
The ECI is not the only frame that give that answer in SR. In the SCI (sun-centered), you get the same answers as the ECI using SR. In the MeCI, VCI, MaCI, JCI, SCI, UCI, and NCI (planets in order), you get the same answers as the ECI. From any *inertial* frame, SR, gives the same answers as from any other inertial frame. LR does not give you the flexibility to choose any inertial frame of your convenience, SR does.
If you are "using SR" from any OTHER frame of reference, then it's predictions are incorrect.
They are correct from any inertial frame of reference.
I have tried to give this inherently contradictory claim some semblance of meaning by assuming you are trying to say something like" "Even though clocks in inertial frames moving relative to each other do, IN FACT, record different amounts of time elapsed, it is NOT because of ANY internal change in the rates at which they tick.
Ontologically, yes.
It is only because the rate at which they tick is irrelevant, and the clocks obey the dictates of time, even when they tick at the same rate.
No.
The way I put it makes no sense, either, not to me at least.
Nor to me.
But apparently you think it is quite sensible. How, in your words, do you get different readings from clocks which tick at the same rate?
We'll get back to that. For now, I'm curious how you take a mental concept which is "real" instead of real (distance, time), apply another mental concept (yard, second), and somehow come out with an objective reality.
How can you even begin to think that SR, and the LT, DOESN'T hold that clocks slow down with speed?
The difference between what you measure and what exists.
The subject matter of physics is not subjective perception.
According the you, it contains phenomena that is not real, but only "real". So, I find your rant just a little hypocritical.
"If distance is just a mental concept..."
Eric, you often seem to think in all or nothing terms. You were doing this before, but I didn't take time to directly respond, because I thought it would become (if not be) clear after more posts. I've said, for example: "They are not "merely" subjective, but they certainly have a subjective aspect to them--time especially."
Let me quote Al on this point one more time: ""We represent the sense-impressions as conditioned by an “objective” and by a “subjective” factor."
See that? There are TWO, not just one, aspects to perceptions. Distance is not "merely" or "just" a mental concept, but it is a concept, not a tangible thing like a rock or a tree. You can travel the whole world over and never see a thing that's called "distance." You will see spaces between objects, and you can call (the measurement of) that gap "distance," but distance doesn't exist, per se, "out there." It's a mental abstraction from what we see. Doesn't make it ONLY a mental concept (as some solipsist might claim). A solipsist would say it's "merely" a mental impression, with no possible correspondence to anything in objective reality, because, for them, there is NO objective reality.
For a realist, mental concepts and tangible objects are different things but there is, or at least can be, a real correspondence between the two.
I am not using the term "concept" as a synonym for "thought" or "impression." Truth and Justice for examples, are concepts. The manner in which a train track appears to me is NOT a concept. It is a sense impression.
Just about every response you make is a question based on a hypothetical..If distance is JUST a mental concept, etc. I will ignore all the rhetorical questions. I never said it was "just" mental. In fact I said the opposite, long before you started down this "IF" track.
"...the distance, being a real thing, is not altered by calling it two different numbers"
OK, good, so far we agree on the fact that two (different) measurements of the same thing don't change it's identity by splitting it into two different things, one real for each person. The distance is what it is, however you may measure it.
But now you say this: "This is amusing to me, since I accept objective realities (distance and time) you have claimed to deny."
You're already on the road to solipisim when you call "distance" an "objective reality." It is NOT an object. Once you start thinking that your conceptions are the things that are "objectively real," then it there is no limit to what "idea" you might call "objective reality.' Soon strictly SUBJECTIVE reality seems to fit that definition of "objective reality." This is were I think you go wrong. You have trouble distinguishing what's subjective from what's objective.
But, again, as long as we agree that 5 different measurements by 5 different observes DOESN'T turn the distance in question into 5 different things, we're on the same page. SR seems to think otherwise, though. The same distance can, in SR, "really" be an infinite number of different things, and they're all "true" or "real." SR will say things like; "Since he he travelling at .6c, the distance for him is only one light year away, not two."
The distance does NOT change, even though the time it takes you to travel it might be less. An "hour's drive" make get someone going 50 mph from point A to B. The fact that someone going 100 mph can go from A to C, with B at the midpoint, does not mean the distance from A to B is shorter for him. The distance from A to B is always the same, assuming that A and B are not moving relative to each other.
If you still agree, then please keep your agreement in mind during the course of future discussion.
"From any *inertial* frame, SR, gives the same answers as from any other inertial frame."
This is just plain wrong, and the whole point of SR is to DENY what you just said here.
Do I really have to say why? Let's take a frame of reference and call it the sun, but let's also pretend to every object is this example is not subject to gravitational forces. Now let's put it two more non-accelerating objects, A (on the left from the sun's point of view) and B on the right, which are separating from each other at .5c.
In relation to object D, which the sun uses as a background, A is not moving, but B is moving to the right at .5c.
So let's look at what "answer" will be given, per SR, from each of these inertial frame.
The sun will say that A is stationary, and that B is moving at 5.C
A will say the same.
B will saying that both A and the sun are moving away from it at .5c.
Clearly this is wrong: ""From any *inertial* frame, SR, gives the same answers as from any other inertial frame."
To carry that on through. The sun will say that B clock is slower than it's own. B will say the sun's clock is slower than its own. This is NOT the "same answer." Nor can both be right. One clock will be slower than the other, but the answer as to "which one and by how much" will NOT be the same.
If you wanted to take it a step further. You could posit a point E, from which all the other 3 are moving at the rate of .25c.
"LR does not give you the flexibility to choose any inertial frame of your convenience, SR does."
That's for sure. LR does not claim that there are an infinite number of motionless "ethers" (the frame of reference YOU are in), all of which are moving relative to each other but all of which are simultaneously at absolute rest when convenient for you. An infinite numbers of standards is NO standard, whatsoever.
This is NOT a virtue of a physical theory, I'm afraid. It's like string theory, where an infinite number of postulated scenarios all get you the same answer. Which one, then, is "correct," pray-tell?
How can you even begin to think that SR, and the LT, DOESN'T hold that clocks slow down with speed?
"The difference between what you measure and what exists."
You are free to concoct your own mystical theory of ontology, no matter how self-contradictory. You are free to utterly reject SR because your preferred theory is not in accord with it. But that STILL will not make SR say what you want it to say. You shouldn't ascribe your idiosyncratic interpretation of "reality" to SR when that's just distorting SR.
Don't say "clocks don't slow down in SR," when all you're really saying SR is wrong and ER (Eric's relativity) is right. "In ER, clocks don't slow sown."
From the day it was invented, SR posited that moving clocks slow down.
Aristotle disagreed with Plato on some points. If you agree with Aristotle on those points, you might call yourself an Aristotelian. But don't say that Plato agrees with Aristotle so you're a Platonist. Don't say that since Plato is obviously wrong, what he really meant to say is exactly what Aristotle said. The thought pattern here seems to be: "Since I am right, I can only conclude that EVERYONE agrees with, and they are saying exactly what I'm saying, even when they explicitly deny that they agree."
According to you:
1. . "SR doesn't have any clocks slowing down." (false, but let's go on)
2. "[clocks in relative inertial motion] both run at the same rate" (also false, but let's go on)
Yet, even so...
3. Clocks in relative motion, despite no clock slowing down, and even though they run at the same rate. will record different amounts of elapsed time.
Because? I'm not surprised that you don't respond to this question.
The sun will say that A is stationary, and that B is moving at 5.C
A will say the same.
B will saying that both A and the sun are moving away from it at .5c.
Clearly this is wrong: ""From any *inertial* frame, SR, gives the same answers as from any other inertial frame."
=====
Therein lies the primary difference between SR and LR. In LR, B will concede that HE is the one moving and that, therefore, his clocks have slowed down relative to the sun, not vice versa. Then, everyone is in agreement. There is absolute simultaneity.
As I said before, SR REQUIRES outright conflict between two different observers, and REQUIRES that each one insist, to his dying day, while fighting for his claim until his dying breath, that HE could not possibly be moving. Only the other guy moves. Without that conflict, SR breaks down. As soon as two observers in relatively moving inertial frames agree about who's moving. SR goes out the window. Now you have LR. If you ever grasp that, you may get a better feel for the difference between SR and LR.
The LT, by the way, were developed by Lorentz (and others, including Poincare) to describe just that scenario. In LR, the train passenger will concede that, as between him and the earth's surface, he is the one nmoving (faster), not the earth, as it obvious from all the circumstance. Both the earth and the train could ALSO be travelling, in tandem, through space at the rate of a million miles an hour, but that would be irrelevant to the question of which of the two clocks will slow down.
The LT does NOT say who is moving. But it does mandate that the moving clock is the one which will slow down.
If you read the article I cited (you suggested that you didn't), then you would also know that theory and experiment that there is not one, and only one, proper "preferred frame" in the universe. As Al said, "All physics are local." The standard for "absolute time" in any given environment will be the dominant center of gravity. On and near earth, that would be the ECI. For the solar system and it's planets, as a whole, it would be the solar system's barycenter.
For measurements on a galactic scale, it would be the center of gravity of the Milky Way, and so on. For the universal as a whole, the CMB is the "cosmic rest frame," according to George Smoot and others.
If you put a large boulder on the ground it will stay there indefinitely. It will never move "on it's own." It will only move if and when some type of force is applied? Why? Good question, ultimately, but one thing seems obvious: What we call gravity holds it in it's place (that and the earth's surface, which prevents it from descending to the center of the earth). It takes work, which requires energy, for anything to overcome the "force" of gravity, even if you're only talking about getting out of bed in the morning. It is work (which requires energy) to get a train going 80 mph and to blast a rocket off to the moon. These are measurable things and there are not beyond our capacity to see and recognize. Once accelerated any object tends, according to the law of inertia, to keep moving (coasting) at the same accelerated rate of speed, even after the accelerating force is no longer being applied.
It is just pig-ignorance to claim that a guy on a uniformly moving train has no way to tell if he is the one moving, relative to the earth.
For whatever reason, the expenditure of energy, resulting in increased speed (from the frame of reference of the local center of gravity), is correlated to a decrease in clock time in the frame of the object which has been accelerated.
Of course what I just said is oversimplified. If energy is used to move an object vertically the clock running with that object will tick slower due to increased speed, but this clock difference will be somewhat offset by that fact that, as it gets farther and farther away from the center of gravity, it clock will speed up for that reason. As it happens, there two effect precisely offset each other at sea level anywhere on the planet. At higher latitudes, objects affixed to the earth move slower (the distance they travel "through space" due to one complete rotation of the earth is less, but it takes the same amount of time an an object at the equator. But, because the earth is an oblate spheroid, the earth's surface at the equator is farther from the center of gravity, which makes the clocks there slow down due to that factor.
Al didn't think is was "mere coincidence" that heavier items fall at the same rate as light ones (i.e., that gravitational mass was equivalent to inertia mass). I would be surprised if it's "just conincidence" that clock rates are the same everywhere on the planet (as sea level, at least), due to seemingly different causes of clock dilation. There must be some underlying connection which we have yet to recogize, I figure.
If the same force is applied to different masses, the one with less mass will be accelerated more. If I hit a bowling ball with a baseball bat, it will probably break the bat, and won't go very far. If I hit a golf ball with the exact same amount of force, it will go hundreds of feet. So one old question was: If gravity is a force, why isn't it a uniform force. It seems to apply more force to heavier objects than it does lighter ones, because it accelerates them the same. Such questions help illustrate the difference between abstract concepts and unadorned empirical observation.
A long standing ancient argument against the claim that the earth was revolving around the sun was that, if it was, a ball that was thrown straight up in the air would not land at the same place it left from because, while it was in the air, the earth would have moved beneath it. The "concept" of inertia had yet to be invented. The Aristotelian concept of an "impetus," which was finite and could therefore only put an object in motion temporarily, prevailed before Galileo. "Inertia" is a concept. You can't directly "observe" it. You can infer it, from what you do see, but you can never "see" inertia. Nor is the cause of inertia observable or apparent. We still can't explain why it exists. It is a concept. It may correspond well (i.e., help explain) what we do see, and be "real" in that sense, but it is not something we can empirically see. We "see" it only through the mind's eye--via deduction.
You would, I guess, say that inertia is "objective reality." Most philosophers would say that it is NOT objective reality, but that it is a mental construct that seems to "correspond" to, and explicate, objective reality as we observe it. Those are two different things.
Reification and hypostatization of mental constructs can, like metaphors or personification, serve as useful linguistic shortcuts and help us "visualize" the concepts under consideration. That said, death does not "really" take the form a person called "the grim reaper."
Time is not "really" some kind of entity, prowling around out there in the world, either.
See the difference?
"[Inertia] may correspond well (i.e., help explain) what we do see, and be "real" in that sense, but it is not something we can empirically see. We "see" it only through the mind's eye--via deduction.
This is a point I have made before to you, but I'm sure it fell on deaf ears at the time. It probably will again.
SR adherents are fond of saying things like "A will see B's clock as running slow, and B will see A's clock as running slow."
But neither A nor B "see" anything of the kind. They DEDUCE it. From premises, whether mistaken or not. In the case or SR, both A and B are deducing (not seeing) how the other's clock is running based on the PREMISE that (in each case) they are not the one moving. But at least one of them must be moving, so at least one of them is basing his deductive conclusions on a mistaken premise.
Witness, for example, the travelling twin in the twin paradox. His deductions give false conclusions because they are based on false premises (i.e., that he is not moving).
But SR disciples will always say he "sees" the clock. They try to turn a mental process (deduction) into an objective physical phenomenon--empirical observation. And they do a great job of fooling themselves, too.
Don't let yourself fall into the same trap of thinking your deductions are indisputable empirical observations. It is fair to say that every "empirical observation" has some kind of deductive element to it. WE are the ones who impute some "meaning" (assuming we bother) to what we see. As Al said, there is both an objective and a subjective element to every sense perception.
I said: "The distance does NOT change, even though the time it takes you to travel it might be less. An "hour's drive" may get someone going 50 mph from point A to B. The fact that someone going 100 mph can go from A to C in the same amount of time, with B at the midpoint, does not mean the distance from A to B is shorter for him. The distance from A to B is always the same, assuming that A and B are not moving relative to each other.
If you still agree, then please keep your agreement in mind during the course of future discussion."
=======
Do you agree, or not?
You said: "Since yard is a mental concept, everyone has a slightly different idea on what a yard looks like, absent some standard that we can measure against."
1. You said it yourself: "...absent some standard we can measure it against." We DO have such standards. And our "idea" of it does not change when we are trying to estimate a number of yards. The "concept" of a yard does not change in the least just because we are not currently in a position to precisely determine just how long a "yard" is because we lack the standardized tools necessary to do so. Again, I am not using the term "concept" as a synonym for "idea," in the sense of a "guess," as you are.
This is something you do often, Eric, as I alluded to in my very first response to you in this latest series of exchanges when I said: "I should have known that you would respond to this question with a semantics slant. I'm not talking about abstract nominal concepts. I'm talking about meaningful physical substance. Substance, not form, not categorization."
You like to think in terms of categories, and you like to treat all items in a category as being identical just because they might share *some* common trait.
You're doing it again here. You establish a category, which you call "mental." Into this category you throw anything that you think is "mental" such as "ideas, concepts, sense impressions, hallucinations, speculation, guesses, etc. Now you treat all these things as identical to each other because, after all, they're all mental phenomena, right?
Perhaps the surest and most common way to go wrong in drawing conclusions is to over-generalize. As a matter of informal logic, this can be categorized as "equivocation," i.e., treating two different things as identical just because, for example, we might use the same word to describe them.
Amongst relativists, the required response to any mention of an "ether" is to smirk, guffaw, and/or ridicule the person mentioning it. Such is the nature of ideology, also known, in some forms, as "political correctness." The idea is to immediately quash all dissenting thought, and to reinforce the dogma one has adopted.
They will typically say: "Einstein PROVED there is no ether over a hundred years ago. fool!!" Heh, they conveniently forget that Al first said he overstepped his bounds if he implied there was no ether and then later said that GR without an ether would be unthinkable ("According to the general theory of relativity space without aether is unthinkable...").
They still howl at the word "ether" because their indoctrinators shield them from that "blasfemy" (assuming the instructors are aware of it in the first place, which they usually are not---they too have been indoctrinated by their predecessors).
"Robert B. Laughlin, Nobel Laureate in Physics, endowed chair in physics, Stanford University, had this to say about ether in contemporary theoretical physics:
The word 'ether' has extremely negative connotations in theoretical physics because of its past association with opposition to relativity. This is unfortunate because, stripped of these connotations, it rather nicely captures the way most physicists actually think about the vacuum....It is ironic that Einstein's most creative work, the general theory of relativity, should boil down to conceptualizing space as a medium when his original premise [in special relativity] was that no such medium existed...The modern concept of the vacuum of space, confirmed every day by experiment, is a relativistic ether. But we do not call it this because it is taboo." [ Laughlin, Robert B. (2005). A Different Universe: Reinventing Physics from the Bottom Down. NY, NY].
Taboo, eh?
I have not read Laughlin's book, but I have come across some interesting excerpts which mirror the thoughts of Carl Woese (in reference to biology and evolution) which I have quoted to you before as I recall. For example:
"Much as I dislike the idea of ages, I think a good case can be made that science has now moved from an Age of Reductionism to an Age of Emergence, a time when the search for ultimate causes of things shifts from the behavior of parts to the behavior of the collective. It is difficult to identify a specific moment when this transition occurred because it was gradual and somewhat obscured by the pretense of myths, but there can be no doubt that the dominant paradigm now is organizational.
Over time, careful quantitative study of microscopic parts has revealed that at the primitive level at least, collective principles of organization are not just a quaint side show but everything – the true source of physical law, including perhaps the most fundamental laws we know....The Transition to the Age of Emergence brings to an end the myth of the absolute power of mathematics. This myth is still entrenched in our culture, unfortunately, a fact revealed routinely in the press and popular publications promoting the search for ultimate laws as the only scientific activity worth pursuing, notwithstanding massive and overwhelming experimental evidence that exactly the opposite is the case...
The myth of collective behavior following law is, as a practical matter, exactly backward. Law instead follows from collective behavior, as do things that flow from it, such as logic and mathematics. The reason our minds can anticipate and master what the physical world does is not because we are geniuses but because nature facilitates understanding by organizing itself and generating law."
http://www.physicscentral.com/explore/writers/laughlin.cfm
I suddenly got interested in this Laughlin book and am showing it here. You may not be the least bit interested, Eric, who knows?
This recommendation is from Phil Wilson, a mathematician who also chides Laughlin for "being rude to his friends" (apparently Laughlin does not elevate math to the same omnipotent status as some mathematicians do):
"Read this book, because there is a lot of well-argued and deeply-insightful science in it. Laughlin is a radical but brilliant scientist firmly rooted in a tradition of observations of nature guiding the way. The prose is often well-crafted and funny, his explanations vivid. The bibliography and notes section is extensive with many useful references and websites."
https://plus.maths.org/content/different-universe
"LR does not give you the flexibility to choose any inertial frame of your convenience, SR does."
This is wrong, by the way. Lorentz, not Al, came up with the notion of "local time." He did so for the sole purpose of using it as a mathematical convenience. Nothing about subscribing to LR as the correct physical theory prevents one from resorting to that convenience.
Lorentz (and Poincare) denied that local time had any physical significance, however To them, it was just a convenient "fiction," which did not represent "true time.
Although he didn't invent it, Al simply claimed that local time was "true time." So, it's not a "matter of convenience" that distinguishes SR from LR. It is an ontological claim about what is "true."
For what it's worth, Lorentz's "local time" was far from the only thing he "borrowed" from Lorentz and/or Poincare.
Al: "I introduced the principle of the constancy of the velocity of light, which I borrowed from H. A. Lorentz’s theory of the stationary luminiferous ether..." (1912)
In 1904 Poincaré wrote: "From all these results, if they were to be confirmed, would issue a wholly new mechanics which would be characterized above all by this fact, that there could be no velocity greater than that of light, any more than a temperature below that of absolute zero.
"Poincaré saw more than a mathematical trick in the definition of local time, which he called Lorentz's "most ingenious idea"...In 1900 Poincaré interpreted local time as the result of a synchronization procedure based on light signals. He assumed that 2 observers A and B which are moving in the ether, synchronize their clocks by optical signals....However, from the point of view of an observer at rest in the ether the clocks are not synchronous and indicate the local time. But because the moving observers don't know anything about their movement, they don't recognize this....contrary to Einstein, who later used a similar synchronization procedure which was called Einstein synchronisation, Poincaré had the opinion that clocks resting in the aether are showing the true time.
In 1901 Poincare said: "There is no absolute space, and we only conceive of relative motion ; and yet in most cases mechanical facts are enunciated as if there is an absolute space to which they can be referred. There is no absolute time. [However, Poincaré himself never abandoned the ether hypothesis].
He [Poincare] spoke literally of "the postulate of relativity"... he noticed that the Lorentz transformation is merely a rotation in four-dimensional space about the origin by introducing ct{\sqrt {-1}}} ct{\sqrt {-1} as a fourth imaginary coordinate, and he used an early form of four-vectors"
That was five years before Al wrote his paper. Lorentz and Poincare were both geniuses. Lorentz won the Nobel prize in 1902. They saw the full implications of Al's theory long before him, and they rejected it. Poincare saw that there were "interesting" parallels to geometry long before Minkowski, but didn't see it as worth pursuing. It wasn't "physically meaningful."
https://en.wikipedia.org/wiki/Lorentz_ether_theory
With respect to the speed of light, Poincare saw the "constancy" as being illusory, due to the kind of fundamental mistake I have pointed out before, saying:
"For an observer, participating himself in a motion of translation of which he has no suspicion, no apparent velocity could surpass that of light, and this would be a contradiction, unless one recalls the fact that this observer does not use the same sort of timepiece as that used by a stationary observer, but rather a watch giving the “local time."
Not surprisingly, according to the wiki article, "Some claim that Poincaré and Lorentz are the true founders of special relativity, not Einstein. For more details see the article on this dispute."
Back to Laughlin's book. A Princeton professor of physics had this to say about it:
"A Different Universe is a book about what physics really is; it is not only unique, it is an almost indispensable counterbalance to the recent proliferation of books by Brian Greene, Stephen Hawking and their fellows, who promulgate the idea that physics is a science predominantly of deep, quasi-theological speculations about the ultimate nature of things. The enterprise of writing this book has my strong endorsement, then, and any disagreements or criticisms should be read in that light.
Those who devour the work of Greene, or decorate their coffee table with Hawking, will find this book a useful antidote. It should spike the interest of those who read the physics popularizers, although in its personalized coverage and opinionated style it is sui generis. My message is this: buy the book."
http://www.nature.com/nature/journal/v434/n7034/full/434701a.html
distance is just a mental concept..."
Eric, you often seem to think in all or nothing terms.
I'm trying to understand your terms.
You were doing this before, but I didn't take time to directly respond, because I thought it would become (if not be) clear after more posts. I've said, for example: "They are not "merely" subjective, but they certainly have a subjective aspect to them--time especially."
Let me quote Al on this point one more time: ""We represent the sense-impressions as conditioned by an “objective” and by a “subjective” factor."
Einstein is, in that article, rejecting a statistical-only interpretation of quantum mechanics, insisting there must be some underlying physical reality, and merely using a statistical description of that reality is insufficient (for him, anyway). Using that quote to attempt to justify the denial of a physical reality is pretty close to quote-mining.
See that? There are TWO, not just one, aspects to perceptions. Distance is not "merely" or "just" a mental concept, but it is a concept, not a tangible thing like a rock or a tree.
I return the compliment: you often seem to think in all or nothing terms. I refer to your apparent insistence that every phenomena is either a mental concept of a tangible things, while physics uses the concepts of physical, non-tangible phenomena, such as the dimensions of spacetime.
You can travel the whole world over and never see a thing that's called "distance."
I have before described distance as physical and non-material. Continuing to say it is not material does not mean it is not physical.
You will see spaces between objects, and you can call (the measurement of) that gap "distance," but distance doesn't exist, per se, "out there."
I disagree. I call that gap distance, whether it has been measured or not, whether it has been perceived or not. Just like mass exists, whether it has been measured in grams or not. A mass does not become a mental concept simply for not being measured, a distance does not become uncertain or void for being unseen. Different amounts of mass are associated with different physical effects (such as the pull of gravity between the two objects), whether the mass is seen or unseen. Different amounts of distance are associated with different physical effects (such as the pull of gravity between the two objects), whether the distance is seen or unseen.
If you want to remove the physicality from distance and make a convincing world-view, you need to come up with a reason why the process of measurement induces an objectivity on the subjective.
I am not using the term "concept" as a synonym for "thought" or "impression." Truth and Justice for examples, are concepts. The manner in which a train track appears to me is NOT a concept. It is a sense impression.
Narrow guage track has a different appearance than standard guage, even if the rails are made from essentially identical bars. Distance is part of the sense-impression.
You're already on the road to solipisim when you call "distance" an "objective reality." It is NOT an object.
Again: you often seem to think in all or nothing terms. I refer to your apparent insistence that every phenomena is either a mental concept of a tangible things, while physics uses the concepts of physical, non-tangible phenomena, such as the dimensions of spacetime.
OK, good, so far we agree on the fact that two (different) measurements of the same thing don't change it's identity by splitting it into two different things, one real for each person. The distance is what it is, however you may measure it.
Once you start thinking that your conceptions are the things that are "objectively real," then it there is no limit to what "idea" you might call "objective reality.' Soon strictly SUBJECTIVE reality seems to fit that definition of "objective reality." This is were I think you go wrong. You have trouble distinguishing what's subjective from what's objective.
When does a separation between two goal posts go from being subjective (in the second paragraph) to being an objective distance in the first paragraph?
SR seems to think otherwise, though. The same distance can, in SR, "really" be an infinite number of different things, and they're all "true" or "real." SR will say things like; "Since he he travelling at .6c, the distance for him is only one light year away, not two."
You still need to explain at what point in the process of converting from what you call a separation to what you call a distance, this particular item becomes impossible.
The distance from A to B is always the same, assuming that A and B are not moving relative to each other.
If you still agree, then please keep your agreement in mind during the course of future discussion.
In my understanding of reality, this is true within a shared inertial frame of A and B. I would not agree more generally until I have more details about how you change their subjective separation into an objective distance.
"From any *inertial* frame, SR, gives the same answers as from any other inertial frame."
This is just plain wrong, and the whole point of SR is to DENY what you just said here.
I was referring specifically to the HK experiment.
Clearly this is wrong: ""From any *inertial* frame, SR, gives the same answers as from any other inertial frame."
I think I have mentioned this before. When you measure phenomena to numbers x and y in frame R, and numbers on the same phemenon R' which are x' and y', they are not supposed to be directly compared. You need to convert x' and y' from frame R' to frame R, and then the numbers will match x and y.
There will be occasions to directly compare observations z in R and z' in R'. In SR, these observations always match.
How can you even begin to think that SR, and the LT, DOESN'T hold that clocks slow down with speed?
It is impossible to discuss this intelligently without a viable theory of space and time.
Don't say "clocks don't slow down in SR," when all you're really saying SR is wrong and ER (Eric's relativity) is right. "In ER, clocks don't slow sown."
I'm not.
From the day it was invented, SR posited that moving clocks slow down.
I agree that from the day it was invented, SR and LR have posited that fewer ticks (or the equivalent thereof) are measured to have passed on one clock. The clock slowing down is one interpretation of this measurement, but not the only.
According to you:
1. . "SR doesn't have any clocks slowing down." (false, but let's go on)
2. "[clocks in relative inertial motion] both run at the same rate" (also false, but let's go on)
Yet, even so...
3. Clocks in relative motion, despite no clock slowing down, and even though they run at the same rate. will record different amounts of elapsed time.
Because? I'm not surprised that you don't respond to this question.
I answered this the last time we had this discussion. Because each measures the other as going through less time. As for which is correct, you would have to bring them side-by-side twice to see which really went through less time, which won't happen in straight-line inertial frames that SR is limited to.
If you read the article I cited (you suggested that you didn't), then you would also know that theory and experiment that there is not one, and only one, proper "preferred frame" in the universe. As Al said, "All physics are local." The standard for "absolute time" in any given environment will be the dominant center of gravity. On and near earth, that would be the ECI. For the solar system and it's planets, as a whole, it would be the solar system's barycenter.
For measurements on a galactic scale, it would be the center of gravity of the Milky Way, and so on. For the universal as a whole, the CMB is the "cosmic rest frame," according to George Smoot and others.
If, running an experiement on earth, I dont use the ECI, but use teh CMB, do I get incorrect answers in LR? If not, that's basically SR with a preferred preference tacked on.
"Inertia" is a concept. You can't directly "observe" it. You can infer it, from what you do see, but you can never "see" inertia. Nor is the cause of inertia observable or apparent.
Again, you insistence on all-or-nothing misleads you.
You would, I guess, say that inertia is "objective reality." Most philosophers would say that it is NOT objective reality, but that it is a mental construct that seems to "correspond" to, and explicate, objective reality as we observe it. Those are two different things.
Again, you insistence on all-or-nothing misleads you. This is from Wikipedia, which describes inertia as innate to matter, not as a concept:
Inertia is one of the primary manifestations of mass, which is a quantitative property of physical systems. Isaac Newton defined inertia as his first law in his Philosophiæ Naturalis Principia Mathematica, which states:[1]
The vis insita, or innate force of matter, is a power of resisting
by which every body, as much as in it lies, endeavours to preserve
its present state, whether it be of rest or of moving uniformly
forward in a straight line.
"[Inertia] may correspond well (i.e., help explain) what we do see, and be "real" in that sense, but it is not something we can empirically see. We "see" it only through the mind's eye--via deduction.
This is a point I have made before to you, but I'm sure it fell on deaf ears at the time. It probably will again.
I agree with this point as stated, deaf ears or no. We only see it via deduction, but it is not dependent on our deduction for its existence.
SR adherents are fond of saying things like "A will see B's clock as running slow, and B will see A's clock as running slow."
But neither A nor B "see" anything of the kind. They DEDUCE it.
Actually, they measure it. Depnding on the perspective, these measurements may or may not involves deductions, in some conditions they are directly seen.
You said: "Since yard is a mental concept, everyone has a slightly different idea on what a yard looks like, absent some standard that we can measure against."
1. You said it yourself: "...absent some standard we can measure it against." We DO have such standards. And our "idea" of it does not change when we are trying to estimate a number of yards. The "concept" of a yard does not change in the least just because we are not currently in a position to precisely determine just how long a "yard" is because we lack the standardized tools necessary to do so. Again, I am not using the term "concept" as a synonym for "idea," in the sense of a "guess," as you are.
OK. How are you using it, specifically?
"Robert B. Laughlin, Nobel Laureate in Physics, endowed chair in physics, Stanford University, had this to say about ether in contemporary theoretical physics:
The word 'ether' has extremely negative connotations in theoretical physics because of its past association with opposition to relativity. This is unfortunate because, stripped of these connotations, it rather nicely captures the way most physicists actually think about the vacuum....
In many ways the Higgs field could be considered an ether.
"Using that quote to attempt to justify the denial of a physical reality is pretty close to quote-mining."
Eric it's impossible to discuss things with you. Once you get an idea in your head, you will never shake it, no matter how many times you're corrected. You seem to read things to say what you expect or want them to say, regardless of what they actually say.
If you read that quote, especially the WHOLE thing, which I posted twice before, Al is INSISTING that we MUST assume that there IS an objective reality. He's NOT denying it. NOR AM I, as have said REPEATEDLY.
"I return the compliment: you often seem to think in all or nothing terms. I refer to your apparent insistence that every phenomena is either a mental concept of a tangible things, while physics uses the concepts of physical, non-tangible phenomena, such as the dimensions of spacetime."
It never ends. As Al says, sense impression have BOTH an objective and subjective aspect. "Every phenonmena?" There you go again. Thinking in terms of categories, making them absolute, and treating every member of a class as being identical to the other. You just don't seem capable of making nuanced distinctions.
1. There are (we presume) objects. Real objects with 3 dimensions, "out there" in the real world.
2. There are "subjects" (who also have a corporeal existence "out there') who have minds. They have both a physical and a mental aspect to their existence. and
3. There is an ultimately mysterious interaction between the two, that we are far from completely understanding.
This is just basic Cartesian dualism, not by any means a novel notion. Although they may argue about details, just about everybody acknowledges and understands this simple distinction. Apparently you are not one of them, though
" while physics uses the concepts of physical, non-tangible phenomena, such as the dimensions of spacetime."
Here you use the word "concepts" as I do. Concepts can REFER to the world, but they are not IN the physical word, pre-existing. The thing(s) the concept refers to may well CORRESPOND to the objective word, but the concept originates with the subject, not the object. To me, the phrase "physical, non-tangible phenomena" is a contradiction in terms. "Phenomena" has it's root in the Greek language, and basically means "to appear," or a thing that "appears," as I recall. "Spacetime" as conceived by Minkowski, for example, never "appears" to anyone in the physical world It is an abstraction, an interpretation, a speculation, etc. It is a CONCEPT, not a thing. If you don't understand that, then I guess you are a subscriber to what is called "naive realism."
"Naive realism is the common sense theory of perception. Most people, until they starting thinking philosophically, are naive realists....Plausible though naive realism may be, it has serious problems, among which is the problem of the variability of perception. The same object may appear differently to different people, or to the same person at different times."
http://www.theoryofknowledge.info/theories-of-perception/naive-realism/
" The naive realist view is that objects have properties, such as texture, smell, taste and colour, that are usually perceived absolutely correct. We perceive them as they really are."
https://en.wikipedia.org/wiki/Philosophical_realism
Perceptions are NOT always "absolutely correct." That's the point here. One you can't seem to grasp.
"I disagree. I call that gap distance, whether it has been measured or not, whether it has been perceived or not.
We DON'T disagree. That's exactly what I'm saying.
Maybe you should do some research on topics like "perception" to get a feel for the kinds of distinctions I'm trying to eludidate here.
Just because not everyone shares your "naive" view, that does NOT mean that they are denying "objective reality." They may simply be denying your definition of it, or your conception of the connection between subject and object.
" Different amounts of mass are associated with different physical effects (such as the pull of gravity between the two objects), whether the mass is seen or unseen."
You give geniuses like Newton, who formulated (invented, conceptualized) mechanics with his F = MA, no credit. You talk as if everybody and his brother walks down the street and physically sEES mass, with their eyeballs. Mass is a concept, sorry. It is not somebody you DIRECTLY "see" in the world.
"In my understanding of reality, this is true within a shared inertial frame of A and B."
See, there you go. This is how it always works will you. You will simultaneously confirm and reject a proposition. Later you will say, selectively, "I've already (affirmed/denied, as suits your purposes at the time) that proposition.
Your use of the qualifying phrase "Wwthin a shared inertial system" implies the OPPOSITE of what you just said you affirmed. So, now, if 5 different observers "see" the same distance differently, now it IS 5 different distances. The goalposts "actually" move around and change the distance between themselves, to accommodate how a subject perceives them.
Sorry, but such a notion implies that you absolutely REJECT, not affirm, the notion of an objective reality.
"This is just plain wrong, and the whole point of SR is to DENY what you just said here.
"I was referring specifically to the HK experiment."
And that's where you're wrong (and in any other contexts, too). In SR (or LR, for that matter) you do NOT get the same answer regardless of which frame you deem to be "at rest." You will always get a differently answer, if and when you switch "frames of reference." To say it's always the same is absurd.
Take The H-K. To simplify let's say that, after the trips were completed, the eastbound (EB) clock, which was the slowest, read 4:59, while the "stationary" Naval observatory (NO) clock (which was in the middle) read 5:00, and the westbound clock (WB) read 5:01.
Remember, these were (in spirit) the ACTUAL observed readings on the clocks when compared after they all came back to rest at the NO and were put next to each other. This was NOT a speculative "thought experiment."
Such an outcome would NOT be predicted by SR. In SR each of the different frames in consideration here would give you DIFFERENT answers, NONE of which would comport with the observations. Nor would the "sun-centered" frame of reference give you this same answer, or the "mars-centered" one. There is only one frame which would predict these precise differences, as actually observed.
"If, running an experiement on earth, I dont use the ECI, but use teh CMB, do I get incorrect answers in LR?"
As I understand it, yes you would get different (incorrect) answers.
"If not, that's basically SR with a preferred preference tacked on."
Yeah, right, it's LR. SR PROHIBITS (or so it says, despite positing one in every calculation it makes) the establishment of a preferred frame. What you saying is about like saying "a cat is a dog if you change all the essential distinguishing characteristics of a cat and substitute those of a dog for them."
"If not, that's basically SR with a preferred preference tacked on."
LR does not require an ether. It does not require something that is absolutely and universally "at rest" with respect to all other things. It simply requires the establishment of a standard "preferred frame" and then using it consistently to ascertain things like time and distance. That's not to say that "just any old preferred frame will do," though. Read what I just said about the H-K experiment.
In the resolution of the twin paradox, there IS a preferred frame which gives you the "right answer." It is the frame of the non-travelling twin. It is NOT the frame of the travelling twin, nor is it some other frame, such as the the CMB.
"In the resolution of the twin paradox, there IS a preferred frame which gives you the "right answer." It is the frame of the non-travelling twin. It is NOT the frame of the travelling twin, nor is it some other frame, such as the the CMB."
I don't know how or why some people deny this. It's implicit in the very premise, which is that one twin is "travelling" while the other is "staying at home." The set-up TELLS you which one is "moving" (relative to the other) and which one isn't.
"he clock slowing down is one interpretation of this measurement, but not the only."
You can interpret things in an infinite number of ways, if you ignore all facts. So what? In the H-K experiment, and everyday in the GPS, clocks do, IN FACT, slow down. And they don't do it whimsically, willy-nilly. They slow down by PRECISE and predictable amounts, depending on the circumstances. Whatever "interpretation" matches the observed facts would be preferred by any scientist over one that sounds metaphysically amazing, but which generates false predictions (such as "no clock will slow down").
" The naive realist view is that objects have properties, such as texture, smell, taste and colour, that are usually perceived absolutely correct. We perceive them as they really are."
Coming back to this subject for minute, just think about it. Does the "object" have a smell? A taste? A color?
To have those things you must have a SUBJECT with the anatomical ability to perceive and process such sensations. Does a snake "see colors." I don't know, but if the color were actually IN the object, and if the snakes sense impressions saw things "as they are," then they would HAVE to see colors.
The "color" we see is, in part, determined by our ability to perceive and interpret things (such as wave lengths of light). The wave length may be "in the object" (we posit that it is) but "color" is not. Such things as smell, taste, and color are what Locke called "secondary'(as opposed to "primary") qualities. According to him, they were not "in" the object, but rather "in" the subject (or, perhaps, "in" the interaction between subject and object).
As I recall, Locke said "objects" have only very few "primary" qualities. Things like length, breadth, depth, solidity, and a few others, maybe.
I am reminded of a funny story about Samuel Johnson, who was a fat ass and apparently didn't bathe too regularly.
He got a on a carriage one day and plopped his ass down next to little girl.
The girl said: "Mister, you SMELL!"
Johnson said. "You're wrong, little girl. I don't smell, YOU smell."
Then he continued: "I stink."
In this tale, Johnson could be seen as the "object" and the little girl as the "subject>'
But neither A nor B "see" anything of the kind. They DEDUCE it.
"Actually, they measure it. Depnding on the perspective, these measurements may or may not involves deductions, in some conditions they are directly seen."
====
As I said, relativists do a great job of convincing themselves. In the typical SR hypothetical, such as the one we were originally dicussing in this thread, where one party (well both, heh) is travelling .8 C or whatever), there are no actual "measurements." What it IF is supposed that each party will "see," is derived SOLELY from deduction based on (contradictory) assumptions being imputed to each observer. You CAN'T understand that, for some reason. Either you just don't give it any real thought, or you're just inherently incapable of recognizing the different between sense mental versus physical "reality>"
Hogg made this point, at some length, and I quoted him, but you apparently can't understand the point. If you use the postulates of SR as your premises then X will follow. If you don't then something else, say Y, will follow. What you are calling "measurements" are not a result of something "seen." They are the logical/mathematical consequence of applying the LT, IN ACCORDANCE WITH, given (unproven and unseen) assumptions.
Now, you can, in some instances, see the thing you're measuring, I agree. With a sensitive enough clocks you can, for example, actually "see" one clock speed up (due to graviational effect) if you raise it two feet. Now, to me, THAT is a measurment, and not merely a deduction (although you assume things about he clocks, etc, of course).
To my knowledge there ha never been, and never will be, a measurement of this kind where EACH clock begins to run slower than the other.
That last post had some typos in it, which makes it confusing to read, but I trust that you can still get the sense of it.
I said: "What you are calling "measurements" are not a result of something "seen." They are the logical/mathematical consequence of applying the LT, IN ACCORDANCE WITH, given (unproven and unseen) assumptions."
SR adherents, for example, like to talk about what you will "see" if you look at "light clock" that is moving. But, tell me, what would you "see" if YOU were the one moving, and the light clock you are looking at was at rest?
My answer: You would "see" exactly the same thing. What you "see" can not, by itself, tell you which clock is running slower. If you were the one moving, and you knew it, you would interpret what you
"see" in the other light clock at being the result of the fact that YOU are moving and the other clock is at rest.
See the point? Mere sense impressions can't answer those kinds of questions. You must posit some premise in order to deduce what you think is the correct interpretation of what you are "seeing."
"If you were the one moving, and you knew it, you would interpret what you "see" in the other light clock at being the result of the fact that YOU are moving and the other clock is at rest."
Just to be explicit, in that case you would conclude that YOUR clock has slowed down, NOT the one you are looking at in the distance. This would, as a said, be a deductive process and not a direct and necessary consequences of the sense impressions you are "seeing."
Somehow, I have the feeling that you will still fail to understand what I'm saying, so let me use an example that's more mundane and less abstract.
What would you "see" if the sun and the planets were revolving around the earth?
What you "see" if the earth and the planets were orbiting the sun?
Answer: The same thing. You simply see what you see. What it "means" or what it "tells you" about "reality" is strictly a matter of interpretation (deductions following from premises).
What would you "see" if the sun and the planets were revolving around the earth?
What you "see" if the earth and the planets were orbiting the sun?
Answer: The same thing. You simply see what you see. What it "means" or what it "tells you" about "reality" is strictly a matter of interpretation (deductions following from premises).
=====
What the "naive" realist "sees" as "objective reality" is the sun rising in the east, and setting in the west while the seasons change on a regular basis.
What a more scientific views "sees" (deduces) is the earth rotating on it's axis while orbiting the sun in an elliptical pattern.
Which of these two (or some third view, if you prefer it) views do you hold to be "objective reality?" How did you arrive at your conclusion? Was it on the basis of "seeing" the earth rotate, or remain motionless, as the case may be? Or was it upon the basis of deductions, which assume certain (ultimately unprovable) assumptions? Do you really think your assumptions MUST be infallible and directly apprehend "objective reality?"
You ask me what is meant by a concept.
If you want to argue about specific details, you might want to read this wiki article, and those it refers you to. A couple of excerpts:
"A concept is an abstract idea representing the fundamental characteristics of what it represents. Concepts arise as abstractions or generalisations from experience or the result of a transformation of existing ideas....In metaphysics, and especially ontology, a concept is a fundamental category of existence.....
It is important to realize that a concept is merely a symbol, a representation of the abstraction. The word is not to be mistaken for the thing. For example, the word "moon" (a concept) is not the large, bright, shape-changing object up in the sky, but only represents that celestial object. Concepts are created (named) to describe, explain and capture reality as it is known and understood."
https://en.wikipedia.org/wiki/Concept
Maybe I should have quoted this excerpt, too:
"Concepts do not encompass all mental representations, but are merely a subset of them."
I am not really all that interested in epistemological discussions for their own sake, Eric, but you seem to be. With that in mind, I will refer you to this wiki article also:
"Abstract and concrete are classifications that denote whether a term describes an object with a physical referent or one with no physical referents. They are most commonly used in philosophy and semantics. Abstract objects are sometimes called abstracta (sing. abstractum) and concrete objects are sometimes called concreta (sing. concretum). An abstract object is an object which does not exist at any particular time or place, but rather exists as a type of thing, i.e., an idea, or abstraction.[1] The term 'abstract object' is said to have been coined by Willard Van Orman Quine.[2] The study of abstract objects is called abstract object theory.....
Another popular proposal for drawing the abstract-concrete distinction contends that an object is abstract if it lacks any causal powers. A causal power has the ability to affect something causally. Thus, the empty set is abstract because it cannot act on other object."
https://en.wikipedia.org/wiki/Abstract_and_concrete
That second paragraph repeats what I was saying when I said that time, as an abstract concept, cannot "cause" effects in the objective world.
That article cites this one:
"It is widely supposed that every entity falls into one of two categories: Some are concrete; the rest abstract. The distinction is supposed to be of fundamental significance for metaphysics and epistemology. This article surveys a number of recent attempts to say how it should be drawn....It is widely agreed that the distinction is of fundamental importance."
http://plato.stanford.edu/entries/abstract-objects/
Speaking to "time" again, I can't, won't, and don't, take some of the statements physicists are fond of making about time literally. Statements like:
1. At the speed of light, time "stops"
2. Time began (was created) with the big bang.
I think it is true that our perception of "time" presupposes change (of one kind or another, not necessarily matter in motion). If nothing ever changed, I don't see how we could have any sense of "time passing." But questions of how and why we perceive time and how we measure it are distinct from the concept of time itself.
Time does not stop when I die, just because I no longer perceive change. I agree with you that time, as we conceive it, does not cease to exist if there are no sentient creatures around to perceive it. That's inherent in the concept (which Newton stated well). Even assuming that there was "nothing" (or at least nothing changing) prior to the big bang, it still makes perfect sense to say that there was a "time" when the universe didn't exist. Like Newton, I think that "true time" (time as a concept, as opposed to time as measured by a clock) flows uniformly, regardless of how (or whether) we perceive it.
That said, I simply cannot conceive of "time" as being the kind of thing that "makes clocks tick." We abstract the notion of "time" from our experiences of events of differing and finite duration. It doesn't make clocks run (slow, fast, or perfectly). It can't. It's simply not that kind of thing
The same is true of distance, as far as I can see. If a football game is being played at Busch Stadium, it's length doesn't change it the middle of game if someone flies over at .8 C and "perceives" it to be longer than it is.
The "length contraction" supposedly "observed" by that craft is in the perception, not in the football field. Even assuming it's yardsticks are longer than ours, the distance between the goalposts does NOT change.
That's one problem with the (in my view completely fictitious) Minkowskian device of "space-time." It conflates two different things and treats them as one thing. Space (distance, if you prefer) and time are NOT the same thing. The fact that we need to know BOTH time and distance to determine "speed," doesn't change that in the least.
Colloquially, people may say that "taking the freeway is shorter" when all they really mean is that you will get there faster by that route. But the actual distance traveled may, in fact, be significantly longer that the distance as measured by an alternate route consisting of surface streets containing a 30 mph speed limit and a multitude of stoplights. Time is not distance, and distance is not time. One doesn't affect or change the other, and least not directly. Speed is not primary. It is merely a composite of (relationship between) it's two separate and distinct elements, time and distance.
However "convenient" the bogus concept of "spacetime" may be when working out mathematical equations, it is not "objectively real." And it is not, as some might claim, a necessity for understanding what we observe. Every description relying on the concept of "spacetime" can be made just as accurately, and much more coherently, in terms of 3 space dimensions and 1 (separate and distinct) time "dimension."
So, in one sense I agree with you (except in reverse) Clocks may slow down with speed. But (true) time doesn't. Clocks may change, and run at a different rate, but "time," as a concept, doesn't. It does seem, however that with increased speed, the natural processes which we use to measure time DO slow down. And that is not "merely" a subjective event or perception. It is a real, objective change. So whereas you say clocks don't change, but time does, I would say the opposite: clocks may change, but time doesn't.
An analogy might be made to the concept of a yard. If a yardstick is frozen, it's length may actually contract as an objective, measurable physical fact. But the length of a yard, as a concept, does NOT change, just because some particular yardstick does.
I also agree with what I take to be your suppositions.
If one can mangle his notion of "objective reality" to the point where he believes it is the "nature of spacetime" which "causes" time dilation and length contraction, then those things (time dilation and length contraction) cannot ALSO be objectively "real," as Hogg (and most others) say they are. It's one or the other, but not both. Any "perception" of distortions to clocks and rods would HAVE to be illusory in that case.
But the whole "spacetime explains it" line of thought is just woefully misconceived to begin with. And, as an empirical matter, clocks DO, actually and demonstrably, show down with speed as an objective matter. So even it the "geometrical" explanation weren't ridiculous, it would be falsified in any event.
Five years ago I said:
In our case, Jill could make an accurate measurement which is NOT an "observation" by Hogg's definition. Any "measurement" she made which she believed indicated that Jack's clock was running slower than hers would have to be based on less than "ideal knowledge" because any such appearance is not of a "real effect." The fact of the matter is that her clock is running slower than Jack's, not the other way around. Furthermore, to the extent assumes she is stationary, she cannot be "ideally informed," since she is in fact moving.
Any attempt by Fowler to legitimatize her erroneous conclusions must therefore reduce to an attempt to make "mere appearance" seem "real" and to make what is mere "seeing" into an "observation" (which it aint).
======
I don't recall all the details of his example now, but Fowler's initial PREMISE was that Jack, not Jill, was the one moving. He then tried to explain why Jill was "perfectly justified" in believing otherwise.
After all kinds of attempts at subterfuge, replete with vague references to the (irrelevant) delay of light signals, fancy-ass terms likes "the relativity of simultaneity," etc., what his "argument" ultimately boiled down to was this: Jill will (without a basis) adamantly DENY that she is moving. She will insist that his clock does NOT read what it reads.
Utterly unconvincing. Preposterous, actually.
Ipse dixit, eh? I have proved I'm not moving because I say I'm not moving.
If you buy that line of "reasoning," then you might also believe that no criminal should ever be convicted of a crime if he denies he did it.
The ancient greek philosopher Parmenides deduced, from his understanding and definition of the word "being," that change was impossible. He went on to say that, therefore, any perception that something was moving was necessarily illusory and false.
One of his disciples, Zeno, a sophist, constructed some very ingenious "paradoxes" concerning motion and change, with the only possible conclusion being, he said, that change and motion were in fact illusory and non-existent.
At the time, nobody seemed to have any satisfactory solutions to the puzzles he proposed. Even so, for some damn reason, he didn't recruit many followers. People still trusted their own senses and experiences, which told them that change was "real".
To me, physics teachers who attempt to demonstrate that SR is "true" are simply modern-day counterparts to the sophistic Zeno. And in a literal as well as figurative way, too. When you boil it down SR requires you to reject the notion of objective motion. Karl Popper used to tease Einstein about his views on time and motion by calling him "Parmenides."
Perceptions are NOT always "absolutely correct." That's the point here. One you can't seem to grasp.
I agree with that completely.
If you read that quote, especially the WHOLE thing, which I posted twice before, Al is INSISTING that we MUST assume that there IS an objective reality. He's NOT denying it. NOR AM I, as have said REPEATEDLY.
Good. However, you were less clear in the quote below.
Sure, he can't run to the moon in 10 seconds flat, but who would say the distance "causes" that. Numbers are not causes, sorry. They are, at best, descriptive conveniences.
A distance is not a number.
To me, the phrase "physical, non-tangible phenomena" is a contradiction in terms.
Good for you. This is a completely non-standard interpretation of physics, but it's a free country.
"Within a shared inertial system" implies the OPPOSITE of what you just said you affirmed. So, now, if 5 different observers "see" the same distance differently, now it IS 5 different distances.
In the frame of the goalposts, there is one distance. Others experience it differently.
The goalposts "actually" move around and change the distance between themselves, to accommodate how a subject perceives them.
No.
"I was referring specifically to the HK experiment."
And that's where you're wrong (and in any other contexts, too). In SR (or LR, for that matter) you do NOT get the same answer regardless of which frame you deem to be "at rest." You will always get a differently answer, if and when you switch "frames of reference." To say it's always the same is absurd.
I don't know if you are deliberately ignoring the requirement of "inertial" or not. From any inertial frame, SR calculates the same result for the HK experiment. SR does not contain the machinery to make calculations from within a non-inertial rest frame.
In the resolution of the twin paradox, there IS a preferred frame which gives you the "right answer." It is the frame of the non-travelling twin. It is NOT the frame of the travelling twin, nor is it some other frame, such as the the CMB.
Certainly, you are showing ignorance by including the CMB in that list. In any inertial from (the stationary twin, the outbound frame of the traveling twin, the inbound frame of the traveling twin, or the CMB), you get the exact same difference in aging (or same difference on clocks) between the two twins.
Whatever "interpretation" matches the observed facts would be preferred by any scientist over one that sounds metaphysically amazing, but which generates false predictions (such as "no clock will slow down").
Again, a person trying to carefully to parse concepts out confuses "has gone through fewer ticks" (which I agree with) with "slowed down (in the sense the clock has changed its behavior)", which I don't agree with. My interpretation matches the observed facts, because all you can observe is having gone through fewer ticks.
What it IF is supposed that each party will "see," is derived SOLELY from deduction based on (contradictory) assumptions being imputed to each observer.
There is no reason to forbid observers from looking at each other's clock. In the example in this post (the two directly approaching each other), has Jill seeing Jack's clock tick off two seconds for every one one she sees tick off on her own clock. Jack sees two seconds tick off on Jill's clock for every second on his. You can run an experiment on this in a lab for sensitive enough clocks.
That said, I simply cannot conceive of "time" as being the kind of thing that "makes clocks tick."
I do not think of time that way. Clocks measure time, but time does not control clocks.
Space (distance, if you prefer) and time are NOT the same thing.
They are different, but both are dimensions of existence.
Every description relying on the concept of "spacetime" can be made just as accurately, and much more coherently, in terms of 3 space dimensions and 1 (separate and distinct) time "dimension."
Unfortunately not true.
"In any inertial from (the stationary twin, the outbound frame of the traveling twin, the inbound frame of the traveling twin, or the CMB), you get the exact same difference in aging (or same difference on clocks) between the two twins."
Heh, is the same difference the "same answer?" Of course not.
Question to guy number 1: Do you hate Hitler? Answer: Yes.
Question to guy number 2: Do you love Hitler? Answer: Yes.
They both gave the "same answer" (yes), eh? Cmon. Are you that dense, or do you just think I am.
Q: Whose clock is running slower, yours or his?
Travelling twin: His
Earth twin: His
The "same answer," eh?
Every description relying on the concept of "spacetime" can be made just as accurately, and much more coherently, in terms of 3 space dimensions and 1 (separate and distinct) time "dimension."
"Unfortunately not true."
Ya think? Why would you say that? Have any examples which demonstrate that, or any "authority" which agrees with that? I've never seen any. I think my statement is taken for granted by physicists.
"In the frame of the goalposts, there is one distance. Others experience it differently."
What do you mean by "experience it differently?" The original question was, does the distance change? Is it a different distance?
You said it's the same distance, then. Are you still saying that? Does the distance change in a different inertial frame. I'm not asking about the "perception" of the distance by a particular subject, I'm asking about the distance itself.
"From any inertial frame, SR calculates the same result for the HK experiment. SR does not contain the machinery to make calculations from within a non-inertial rest frame."
Completely wrong. Assuming they were in an inertial frame, SR would give completely different predictions than were observed AND every other inertial frame would a different answer than another. You STILL can't grasp that?
If the naval observatory's frame were used, it would say that both the other clocks are slowing down equally. (Not what happened, one was faster, one was slower).
The EB plane would say both of the the other's slowed, with the WB slowing more.
The WB plane would say just the opposite of what the EB plane said.
Do you think there is some magical about an ideally inertial frame of reference that would suddenly make the clocks on the plane conform to the all these different predictions? Would all clocks run slower than all others in "an inertial frame," ya think?
Yes or no?
" In the example in this post (the two directly approaching each other), has Jill seeing Jack's clock tick off two seconds for every one one she sees tick off on her own clock. Jack sees two seconds tick off on Jill's clock for every second on his. You can run an experiment on this in a lab for sensitive enough clocks."
No, that's not what the example said at all. Fowler made it clear that the "conclusions" Jill arrived at were done on the basis of deduction, not on the basis of "seeing" Jack's clock.
An excerpt:
"Therefore, Jill will conclude that since C2 reads 10 seconds as she passes it, at that instant
C1 must be registering 6.4 seconds. Jill’s own clock reads 8 seconds at that instant, so
she concludes that C1 is running slow by the appropriate time dilation factor of 4/5."
That whole example involved multiple clocks. At first Fowler concedes that:
"As Jill passes Jack’s second clock, both see that his clock reads 10 seconds, hers reads 8 seconds"
This would mean that Jill's Clock is the one running slower, and that, therefore, she would be the one moving.
But then she "calculates," using the LT and assuming that she is NOT moving, what some other (unseen) clock MUST say. That way she "proves" what she presupposes, even though the clock evidence right in front of her face disputes her conclusions.
Looking at Fowler's example again, the cheap trick he uses is obvious. He creates a set of data based on the fact that Jill is moving (her clock shows 8 seconds elapsed, his shows 10, the distance is 6 light seconds, etc.
Then he tells you to look at it from her perspective, because she thinks she's not moving. But, if she really thought that, then she would not expect to see ANY of the facts which Fowler claims ARE facts. But, all the same, according to him, she uses this "false" (to her) data as the basis for her assumptions. She would NOT use that data if she thought she were the one at rest.
If that's what she thought, she would compute this distance to be six light seconds, just as Jack did. She would expect her own clock to read 10 seconds (as his did), not 8 seconds, etc.
He simply takes some date from Jack's frame as "true" then says Jill will perceive, and use that "false' (to her), that very same data to make her calculations in her frame, which she WOULDN'T do if she really thought Jack was moving at .6c while she remained stationary.
I'm sure you will be unable to see this, so I'm really just talking to myself, I suppose.
There are other obvious flaws in his sophism, too, of course. He attempts to use "photography" to prove how well Jill knows SR. If she knew shit about it, she would know that the lorentz transformations have exactly NOTHING to due with light speed delay, and she would not use that irrelevant data to try to "explain" why her LT calculations are supposedly "right."
"In any inertial from (the stationary twin, the outbound frame of the traveling twin, the inbound frame of the traveling twin, or the CMB), you get the exact same difference in aging (or same difference on clocks) between the two twins."
They both gave the "same answer" (yes), eh? Cmon. Are you that dense, or do you just think I am.
Q: Whose clock is running slower, yours or his?
Travelling twin: His
Earth twin: His
The "same answer," eh?
I thought that, at one point, we went over this in detail.
Let's use the three-clock version to make this simpler. Clock A stays on planet. Clock B passes by A, going at .5c (the start point) relative to A. After 10 ls (light seconds), clock C passes clock B going directly toward clock A. If the speed of C relative to A is also .5c, then the speed of C relative to B is .8c. C synchronizes to B when they meet (rendezvous point). Then, when C passes A, they compare (comparison point).
Viewpoint of clock A: it takes 20 seconds for B to move to the rendezvous point, and 20 seconds for C to move to the comparison point. 40 seconds pass on clock A. Meanwhile, on clock B, (approximately) 17.32 seconds pass between the start and the rendezvous, and then 17.32 seconds pass on clock C between the rendezvous and comparison. Clock C reads 34.64 compared to clock A reading 40.
Viewpoint of clock B: for 17.32 seconds between the start point and the rendezvous point, clock A is moving at .5c before clock C goes by at .8c. After clock C passes, it takes another 28.86 seconds on clock B (it's a simple algebra equation) before clock C catches up to clock A. In that 28.86 seconds moving at .8c, clock C ticks another 17.32 seconds, making a total of 34.64. Meanwhile, clock A moved for a total of 46.18 seconds at .5c, ticking off 40 seconds. Clock C reads 34.64 compared to clock A reading 40.
Viewpoint of clock C: clock B is moving toward clock C at .8c, clock A at .5c. The 17.32 seconds between the start point and the rendezvous point on clock B takes 28.86 seconds on clock C to cover what in C's frame is 23.09 ls. Clock A is moving at .5c, and takes 46.18 seconds in clock C's frame. Clock A has 40 seconds pass in that time. Clock C synchronizes with B's 17.32 at the rendezvous, and has another 46.18-28.86=17.32 seconds pass, so has 34.64 at the comparison point. Clock C reads 34.64 compared to clock A reading 40.
In all three frames, clock C reads 34.64, clock A reads 40. The prediction is the same using any inertial frame.
Every description relying on the concept of "spacetime" can be made just as accurately, and much more coherently, in terms of 3 space dimensions and 1 (separate and distinct) time "dimension."
"Unfortunately not true."
Ya think? Why would you say that? Have any examples which demonstrate that, or any "authority" which agrees with that? I've never seen any. I think my statement is taken for granted by physicists.
To use GR at all, space-time is interpreted as a four-dimensional manifold of negative curvature, IIRC, regardless of what you think.
"In the frame of the goalposts, there is one distance. Others experience it differently."
What do you mean by "experience it differently?" The original question was, does the distance change? Is it a different distance? You said it's the same distance, then. Are you still saying that? Does the distance change in a different inertial frame. I'm not asking about the "perception" of the distance by a particular subject, I'm asking about the distance itself.
If distance is defined as an invariant mental concept, obviously not.
If distance is defined as the path length of the shortest geodesic on a manifold of negative curvature, it can change.
So, let's say the distance does not change, but the length of the shortest path changes.
Completely wrong. Assuming they were in an inertial frame, SR would give completely different predictions than were observed AND every other inertial frame would a different answer than another. You STILL can't grasp that?
Again, I could have sworn that you knew otherwise. As in the example above, if you use an inertial frame, the times on all three clocks in the HK experiment read the same.
If the naval observatory's frame were used, it would say that both the other clocks are slowing down equally. (Not what happened, one was faster, one was slower).
Not an inertial frame.
The EB plane would say both of the the other's slowed, with the WB slowing more.
Not an inertial frame.
The WB plane would say just the opposite of what the EB plane said.
Not an inertial frame.
Do you think there is some magical about an ideally inertial frame of reference that would suddenly make the clocks on the plane conform to the all these different predictions? Would all clocks run slower than all others in "an inertial frame," ya think?
All inertial frames give the same predictions. They do not force the clocks to do anything.
" In the example in this post (the two directly approaching each other), has Jill seeing Jack's clock tick off two seconds for every one she sees tick off on her own clock. Jack sees two seconds tick off on Jill's clock for every second on his. You can run an experiment on this in a lab for sensitive enough clocks."
No, that's not what the example said at all.
I agree, Fowler did not say this in his example. It is nonetheless true, and nothing he said contradicted this.
I'm sure you will be unable to see this, so I'm really just talking to myself, I suppose.
It's not that I don't see your point of view, it's that I find it unnecessarily limiting.
Let's use the three-clock version to make this simpler. Clock A stays on planet. Clock B passes by A, going at .5c (the start point) relative to A. After 10 ls (light seconds), clock C passes clock B going directly toward clock A. If the speed of C relative to A is also .5c, then the speed of C relative to B is .8c. C synchronizes to B when they meet (rendezvous point). Then, when C passes A, they compare (comparison point).
Viewpoint of clock A: it takes 20 seconds for B to move to the rendezvous point, and 20 seconds for C to move to the comparison point. 40 seconds pass on clock A. Meanwhile, on clock B, (approximately) 17.32 seconds pass between the start and the rendezvous, and then 17.32 seconds pass on clock C between the rendezvous and comparison. Clock C reads 34.64 compared to clock A reading 40.
Viewpoint of clock B: for 17.32 seconds between the start point and the rendezvous point, clock A is moving at .5c before clock C goes by at .8c. After clock C passes, it takes another 28.86 seconds on clock B (it's a simple algebra equation) before clock C catches up to clock A. In that 28.86 seconds moving at .8c, clock C ticks another 17.32 seconds, making a total of 34.64. Meanwhile, clock A moved for a total of 46.18 seconds at .5c, ticking off 40 seconds. Clock C reads 34.64 compared to clock A reading 40.
Viewpoint of clock C: clock B is moving toward clock C at .8c, clock A at .5c. The 17.32 seconds between the start point and the rendezvous point on clock B takes 28.86 seconds on clock C to cover what in C's frame is 23.09 ls. Clock A is moving at .5c, and takes 46.18 seconds in clock C's frame. Clock A has 40 seconds pass in that time. Clock C synchronizes with B's 17.32 at the rendezvous, and has another 46.18-28.86=17.32 seconds pass, so has 34.64 at the comparison point. Clock C reads 34.64 compared to clock A reading 40.
In all three frames, clock C reads 34.64, clock A reads 40. The prediction is the same using any inertial frame
=== I just started looking at this and there are a few things that are not clear to me, but let me start with this:
1. "In all three frames, clock C reads 34.64, clock A reads 40. The prediction is the same using any inertial frame."
Assuming for the moment that this is accurate and relevant (which I don't, yet), as it relates to the H-K, the first question would be "so what?" If all three are wrong (not in accordance with what the clocks actually read), who cares?
2. You say : "After clock C passes, it takes another 28.86 seconds on clock B (it's a simple algebra equation) before clock C catches up to clock A." Where does this come from. As I understand you, it takes only 17.32 seconds on B's clock for A to move (in his view) 10 ls away from from him. Presumably it would take another 17.32 seconds for A to move ANOTHER 10 ls away from him. So why should it take MORE (28.86 vs only 17.32) time to get the SAME distance to A (10 ls) when C is moving away (in his view) even faster?
This is just another example of selectively grabbing data from one frame and imputing to another. It's no wonder the results are self-contradictory.
3. You say: "Viewpoint of clock C: clock B is moving toward clock C at .8c, clock A at .5c" For one thing, as I uderstood your example, clock B would, at this point, be running AWAY from C, not toward him.
I will stop here, for now. Either I'm misreading the problem, or else you are not stating it correctly
"To use GR at all, space-time is interpreted as a four-dimensional manifold of negative curvature, IIRC, regardless of what you think."
I thought we were talking about SR, not GR. Within the framework of SR the "4 dimension" view just leads to physically absurd "explanations" of what's happening in the real world. You don't get those kind of absurdities using a 3 + 1 format.
I won't try to talk about GR in detail, because I really don't know either the mathematical or the conceptual details well enough. But, generally speaking, Newton's gravity explain things quite well. They say the mission that got us to the moon and back used ONLY newtonian notion of gravity (no GR). Assuming that GR predicts a couple of things better (like Mercury's orbit), that does not mean that any particular view of space and time is more accurate. There are tons of things that GR DOESN'T explain too, like phenomena in QM and the "expansion" of the universe (unless you dream of fantastical amounts of "dark matter" and "dark energy" on an ad hoc basis.
It's all still a matter of "interpretation." Al took a "field" view of GR, as I understand it, which is quite different than the "geometrical" interpretation, which you seem to be suggesting is the ONLY proper view.
"If distance is defined as the path length of the shortest geodesic on a manifold of negative curvature, it can change." I really have no idea of what this is supposedly to be saying about objective, physical reality.
"So, let's say the distance does not change, but the length of the shortest path changes."
What is a "path?" in this sense? I gave an example of times when people might say taking the freeway is "shorter," but ONLY because they are confusing a measurement of TIME with a measurement of distance. Is that the kind of thing you mean?
Like saying: "the "PATH" to the Chicago is shorter if you take the freeway?" Is that the kind of thing you're saying?
Back to this example for a minute (still pending further explanation). You say:
1. Viewpoint of clock A: it takes 20 seconds for B to move to the rendezvous point, and 20 seconds for C to move to the comparison point. 40 seconds pass on clock A.
2. "Clock C reads 34.64 compared to clock A reading 40."
3. "In all three frames, clock C reads 34.64, clock A reads 40. The prediction is the same using any inertial frame."
Again, assuming this is "true," can't you see that it contradicts the basic claim of SR that "each observer will "see" the other's clock as going slower?"
If both A and B see A's clock as being 40 and B's as being 34.64, THEN they AGREE on who's clock is slower and they share the belief that A is stationary while B is moving.
"If both A and B see A's clock as being 40 and B's as being 34.64, THEN they AGREE on who's clock is slower and they share the belief that A is stationary while B is moving."
Once again you have shifted to an LR viewpoint, all while claiming that you are expounding upon SR. This is actually pretty standard for SR advocates. They consistently alternate between adopting "absolute" vs "relative" theories (suppositions). They have to. There can be NOTHING that's both meaningful concrete said about any motion from a strictly relative viewpoint. At some point, they must, as in the twin paradox, say that one really is moving faster DESPITE the fact that their theory supposedly says this can never be known.
I'm sure you will be unable to see this, so I'm really just talking to myself, I suppose.
"It's not that I don't see your point of view, it's that I find it unnecessarily limiting."
Well, I suppose that from one perspective, rejecting rather than accepting, and condemning rather than extolling, fallacious sophistry is "limiting." And it would only be deemed "necessary" by someone who respects, and insists upon adherence to, acceptable standards of logic, I suppose.
But I will accept those "limits" even though they may put some restraints on me accepting my fondest wishes as being "true."
I just said: " At some point, they must, as in the twin paradox, say that one really is moving faster DESPITE the fact that their theory supposedly says this can never be known."
Fowler has a section entitled: "You Really Can’t Tell You’re Moving!" That's it, exclamation mark and all. I don't know how to reproduce it in this format, but in his title the word "really" is italicized for special emphasis.
I have addressed this sophistry with you at great length in the past, including pointing out what Galileo, in his "parable of the ship," really said (as opposed to what many SR advocates claim he said), and I won't repeat it here. The whole "you can't tell you're moving" narrative is so obviously at odds with fundamental physics that it really shouldn't require any "debunking." But, nonetheless, SR adherents will insist that it is physically "true."
For a whole host of valid physical reasons, a guy on an inertially moving train KNOWS that he is moving relative to the earth surface, and not vice versa. That's one reason SR, as a physical theory (as opposed to a mathematical scheme for making calculations), is irredeemable (to use Hillary Clinton's words) from the get-go. To base an entire physical theory on an obviously invalid premise does not hold much promise. Kinda like Parmenides concluding, on the basis of bogus a priori deduction, that change is impossible.
Although of interest from both an historical perspective and on the basis of it's logic, Parmenides' theory of "Being" is (almost) universally rejected as being practically "true."
"For a whole host of valid physical reasons, a guy on an inertially moving train KNOWS that he is moving relative to the earth surface, and not vice versa."
And, needless to say, this is true even if he can't "feel" his motion. Basing your notion of objective truth and reality on what a subject "feels" is just bad policy for physical theories. Positivistically basing your definition time and distance on what any (and every) subject "perceives" it to be is just as bad.
"Basing your notion of objective truth and reality on what a subject "feels" is just bad policy for physical theories."
And to repeat myself, this is precisely what Galileo was ultimately demonstrating. He concluded that the earth is in fact moving, even though we don't "feel" it, and that we can "know" this by systematic analysis, contrast, and comparison of our collective sense perceptions, i.e., by reason or deduction founded upon empirical observations.
" LR does not claim that there are an infinite number of motionless "ethers" (the frame of reference YOU are in), all of which are moving relative to each other but all of which are simultaneously at absolute rest when convenient for you. An infinite numbers of standards is NO standard, whatsoever.
This is NOT a virtue of a physical theory, I'm afraid. It's like string theory, where an infinite number of postulated scenarios all get you the same answer. Which one, then, is "correct," pray-tell?
====
To illustrate the point here, which I suspect you do not quite understand, let me give a concrete example.
I tell you that x + y + z + a + b + c = exactly 10,201.00093. Then I ask you: What are the values of x, y, etc.?
You have a variety of possible responses. One could simply be that there is not enough information given to definitely answer the question.
Another possible answer would be to start attributing various arbitrary values to all those variables in such a fashion as to make their sum be 10,201.00093. And then claim that all those (infinite) possible values are "correct." That's what SR does. No one else would, of course, but still......
In an interesting 2010 paper, entitled "Lorentzian theories vs. Einsteinian special relativity - a logico-empiricist reconstruction," Laszlo E. Szabo says the following:
"Due to the popular/textbook literature on relativity theory, there is a widespread
aversion to a privileged reference frame. However, like it or not, there is a privileged
reference frame in both special relativity and classical physics. It is the frame of reference
in which the etalons are at rest. This privileged reference frame, however, has nothing to do with the concepts of “absolute rest” or the aether; it is not privileged by nature, but it is privileged by the trivial semantical convention providing meanings forthe terms “distance” and “time”;...."
I think I have cited you to this "logical analysis" before. Perhaps you would like to read it some time and show, line by line, why it is false, it you deny his claims, eh?
Regarding "spacetime," he also says this, for example:
According to this widespread view, special relativity was, first of all, a radically new theory about space and time....[But] , in comparison with the pre-relativistic Galileo-invariant conceptions, special relativity tells us nothing new about the geometry of space-time....the two theories provide identical description of the behavior of moving physical objects....Special relativity and the Lorentz theory are completely identical in both senses, theories about space and time and as theories about the behavior of moving physical objects.
http://philsci-archive.pitt.edu/5339/1/leszabo-lorein-preprint.pdf
object
Another excerpt from the Szabo paper:
"Many of those, like Einstein himself (see Point 25), who admit the “empirical equivalence” of the Lorentz theory and special relativity argue that the latter is “incomparably more satisfactory” (Einstein) because it has no reference to the aether...the role of the aether could be played by anything else; the aether does not constitute a privileged reference frame...the hypothesis about the existence of aether is logically independent of both the theory and special relativity."
=====
This guy has obviously studied both theories, from both a historical and analytical standpoint, at great length. Although I don't pay any attention to the math, what he says makes perfect sense to me. It seems there are a lot of unwarranted "myths" about SR that don't hold up to logical analysis. It would follow that those who subscribe to these myths don't really comprehend the logical structure of the theory.
He also denies that SR allows for an interpretation (like yours) that says there are no "real" changes in physical objects (clocks and rods, for example):
"Many believe that it is an essential difference between the two theories that relativistic deformations like the Lorentz–FitzGerald contraction and the time dilatation are real physical changes in the Lorentz theory, but there are no similar physical effects in special relativity... relativistic deformations are real physical deformations also in special relativity theory. One has to emphasize this fact because it is an important part of the content of relativity theory. It must be clear, however, that this conclusion is independent of our main concern."
Another way of looking at Fowler's obvious inconsistencies:
Fowler posits the two "ground clocks" to be synchronized in Jack's frame. Jill seems to be perfectly aware of this and is trying to "test" it. For that reason, they agree to set their respective clocks to zero at the first clock, and then to "take pictures" of the first clock when the second clock is reached by Jill.
When she gets to clock number 2, she sees that it reads 10 seconds. Because her clock only shows 8 seconds (which indicates that SHE is the one moving), she promptly asserts that clock 1 "cannot possibly" read 10 seconds. But, given the premises, it would HAVE to. They both know the two clocks are synchronized in Jack's frame. Therefore clock 1 MUST read the same as clock 2, whether Jill wants to deny it, or not. She aint really all that bright, now, is she?
Nick Percival, who has a degree in physics from Harvard and who co-founded TeacherWeb.com (which provides technologically patents programs used by educators to communicate with students and parents),
has a number of blog entries (and published articles) pertaining to the GPS, SR, and similar subjects. In one such entry, he says:
"[SR] was NOT derived to be used by a 3rd party to compare clock A and B as the results will vary widely depending on the state of the 3rd party."
"Vary widely,: eh? Apparently, like me (and everyone else with an understanding of the topic who I read), but unlike you, he does NOT believe that SR will give you the same answers in every inertial frame. I've already explained to you why that CAN'T be the case, but you haven't been deterred in the least. You just keep repeating, over and over, your mistaken claim, and asserting it as though it were an established fact. In the blog entry I'm citing here, he too explains WHY this cannot be true. Maybe you will understand him, if you can't understand me, eh?
He also acknowledges the obvious implications of the GPS data, as follows:
"The empirical data shows that absolute velocity causes a change in the proper time accumulation rate of clocks. This is a physical, asymmetric, absolute effect and affects clocks in inertial and non-inertial (e.g., accelerating, rotating) frames. Special Relativity’s time dilation equation is a function of relative velocity and, as such, is inherently symmetric and observer dependent and cannot be the cause of asymmetric decreasing of proper time accumulation rates."
"The earliest data on time dilation just measured that A observed “clock” B rates to be slower than his “clock” A rates – however, what B would observe was NOT measured. These one way measurements were consistent with Special Relativity and were interpreted as confirming Special Relativity. However, subsequent data that directly measured both the A and B perspectives has shown that clock rate differences as a function of velocity are NOT symmetric as Special Relativity predicts, but rather are asymmetric."
With respect to the H-K computations in particular, he says:
"Even though one is using an equation that looks like Special Relativity time dilation and one is using velocity “relative” to the ECI frame, one is NOT actually using Special Relativity time dilation. If one actually just used Special Relativity and measured the relative velocities of the airborne clocks, one would NOT compute what the data results were
You can read about the basis he uses for his conclusions here, if you care to:
http://www.naturalphilosophy.org/site/nickpercival/2015/06/02/empirical-data-does-not-match-special-relativity-time-dilation/
This video is rather humorous, although one really shouldn't laugh because it's so sad. Two people are asked to solve a "trick" question about rate of speed.
The "logic" used is unfathomable. Certain obvious and necessary implications seem to completely overlooked by some people. These two are not alone. There are videos all over the internet involving people who are completely stumped by this trick question.
https://www.youtube.com/watch?v=tOFJpsDmKvU
This one is even funnier. The person answering the question says she is making sense, while her questioner is not. She says he doesn't know the right answer, but she does. Quite typical, eh?
https://www.youtube.com/watch?v=Qhm7-LEBznk
This physicist says:
"It's a common misconception that special relativity cannot handle accelerating objects or accelerating reference frames. Sometimes it's claimed that general relativity is required for these situations, the reason being given that special relativity only applies to inertial frames. This is not true. Special relativity treats accelerating frames differently from inertial frames, but can still deal with accelerating frames."
http://math.ucr.edu/home/baez/physics/Relativity/SR/acceleration.html
Here again we see confusion about what SR is and what the theory logically entails. He says "Special Relativity can still deal with accelerating frames," but all he's really saying is that physics in general, not SR, can deal with accelerating frames.
Physics uses, and has ALWAYS used, LR, not SR, when dealing with accelerating frames. LR has ALWAYS made accurate predictions in these cases while SR NEVER has. Why anyone would prefer a theory that only deals with a minute fraction of observed motion, with one that accurately predicts ALL motion is a mystery to me.
All the more so when the all-encompassing theory gives perfectly clear, reasonable, and comprehensible physical explanations while the limited one does NOT.
This guy also says:
"Note that the speed of light is rarely a constant in non-inertial frames, and this has been known to cause confusion."
Exactly. This is what LR tells you.
NY and LA are always the same distance from each other. They do not move RELATIVE TO EACH OTHER. SR says, that in inertial frames at least, the speed of light is independent of the motion of the receiver, and hence should be constant even if two objects are moving with respect to each other, but this is especially obvious when the two objects are NOT moving relative to each other.
In practice, using synchronized clocks, we find that, as an empirical matter, it takes light longer to go from NY to LA than it does for it to go from LA to NY. This is just what LR would predict. "SR" will predict the same thing if you mix in some LR with it. But then it's no longer SR.
Edit; I said: it takes light longer to go from NY to LA than it does for it to go from LA to NY."
This should be reversed. I should have said "less time" instead of "longer."
Eric, I'm going to try one more time get you to understand the difference between LR and SR. Keep in mind that neither SR or LR depend on the notion of "absolute rest" or an "ether." That seems to be one of your main misconception about the two.
Boiled down, the fundamental difference is that LR retains absolute simultaneity while SR posits relative simultaneity.
So, what does that mean? Although those two terms may sound quite esoteric and complicated to some, the concept, boiled down, is really quite simple and easily understood.
1. Absolute simultaneity simply means that the LT are "directional" and not "symmetrical." And all that means is that if Observer A's clock is slowed down (and lengths contracted) as compared to observer B, then B's will observer B will agree with him. He will deem his clock to be slower also. But LR is not about "observers," it's premises apply to the "real world," not observers. If for any reason B did not "see" it that way, that would be irrelevant. According to the theory his clock did, as a matter of objective fact, slow down, whether observer B knows it, or is willing to admit it, or not.
Relatives simultaneity simply means that the LT are "reciprocal" and "symmetrical." And all that means is that if Observer A believes or assumes that B's clock has slowed down, then B MUST dispute that and claim that it is A's clock, not his own, that has slowed down when they are moving with respect to another. And, SR, says, they are "both" right insofar as (supposedly) no one can ever know who's moving, so no one can be wrong, and everyone is equally "right."
That's the difference. LR has unchanging standards for time and distance, and purports to address a knowable objective reality. SR has no uniform standards, and claims, in effect, that motion is a matter of "perception" and therefore can neither be proven nor disproven, because it's basically unknowable.
With that in mind, let's take a look at what this physicist says:
"Do moving clocks *always* run slowly?
A commonly heard phrase in the realm of special relativity is "Moving clocks run slowly". But—even in the context of special relativity—is it always true? The answer is no. It's only true when a clock's ageing is measured in an inertial frame. This assumption of inertiality might not always be stated explicitly in textbooks, but it's always there."
[But what does this mean, by this? He goes on, saying]
"The inertial clock measures the orbiting clock to age slowly . This can only mean that the orbiting clock measures the inertial clock to be ageing quickly. The frame of the orbiting clock is accelerated, and the (inertial) clock that moves within this frame ages quickly, not slowly."
[This is, simply stated, acknowledging the basic premise of LR that clock changes are directional, not reciprocal; absolute, not relative; and that simultaneity is absolute, not relative. Any analysis of accelerated frames therefore requires the employment of LR. SR doesn't apply].
Do you understand this? Do you dispute any of this?
By the way, here's the link for that last quotation:
http://math.ucr.edu/home/baez/physics/Relativity/SR/movingClocks.html
To repeat: "That's the difference. LR has unchanging standards for time and distance, and purports to address a knowable objective reality. SR has no uniform standards, and claims, in effect, that motion is a matter of "perception" and therefore can neither be proven nor disproven, because it's basically unknowable."
In common parlance, as it is understood by most people (maybe not you), this means that LR is an "objective" (realist) theory, while SR is a "subjective" (solipsistic) theory.
That second physicist from the Baez site says: "A commonly heard phrase in the realm of special relativity is "Moving clocks run slowly". But—even in the context of special relativity—is it always true? The answer is no."
But you might have noticed, that according to his own analysis, it IS the moving clock which runs slowly. What he was really asking was NOT whether moving clocks run slowly, but rather, does "reciprocity" (relative simultaneity) always apply.
"What he was really asking was NOT whether moving clocks run slowly, but rather, does "reciprocity" (relative simultaneity) always apply."
Put another way, is the accelerated observer required to say that the other clock is moving, and therefore it's clocks must be running slow?
The answer is NO. He is required to acknowledge that it is HIS clock that has slowed down, not the "other guy's." It is not that moving clocks don't always run slow, it is just that not every observer is not required to insist that the other clock is the one moving. That's what the physicist was really driving at.
In that sense, i.e., in the sense that a (false) claim that the other clock is the one moving must be treated as "true," that "moving" clocks don't always run slow.
Earlier I asked you if you thought that a "perfectly inertial" frame would "suddenly" change (from the way they are perceived in accelerating frames) the behavior of clocks. You didn't answer that question as I recall. Let me illustrate the question to you in a different way (as I have done before).
Assume that a moving train accelerates to a speed of 80 mph at the rate of one mph per day for 80 days. According to physics (including SR) acceleration is absolute, so that would mean that for those 80 days, the train clock must be treated as moving and therefore having the slower clock.
The train ultimately reaches the speed of 80 mph, and, at that point, it maintains a uniform rate of speed (80 mph) for one hour. Then it begins decelerating, again at the rate of a mph per day, until it comes to a complete stop 80 days later. During this period, his clock is running slow.
Now, how about the one hour when he was moving uniformly? Did some "magic" occur which SUDDENLY made his clock run fast and SUDDENLY made clocks on the earth's surface run slow, compared to his. Did that "magic" wear off the second he started decelerating?
Whaddaya think?
NIck Percival said: ""The empirical data shows that absolute velocity causes a change in the proper time accumulation rate of clocks. This is a physical, asymmetric, absolute effect and affects clocks in inertial and non-inertial (e.g., accelerating, rotating) frames."
He is manifestly correct.
"It is not that moving clocks don't always run slow, it is just that not every observer is required to insist that the other clock is the one moving. That's what the physicist was really driving at."
The title of his article was misstated. It should have been something like: "Is an observer *always* required to insist that HIS clock is running fast?"
To reinforce the point (I'm not sure that any amount of reinforcement will help in your case, but....): You say that SR "does not apply" in non-inertial frames. What you leave out (or completely forget about) is that even SR holds that acceleration is absolute (not "frame-dependent'). So, then, the natural question would be "what theory *does* apply in non-inertial frames?"
We have just seen the answer, which is, "Why, a theory of absolute motion (LR), of course." Which is, in fact, what the GPS uses and relies on, not SR.
More reinforcement:
If SR is "wrong," then how can it make correct predictions? That's easy. Because it imitates and simulates LR, but confines itself to inertial frames. It, like LR, merely posits a preferred frame (the one you're in) and goes from there.
As Szabo said: "... like it or not, there is a privileged reference frame in both special relativity and classical physics. It is the frame of reference in which the etalons are at rest. This privileged reference frame, however, has nothing to do with the concepts of “absolute rest” or the aether; it is not privileged by nature, but it is privileged by the trivial semantical convention providing meanings for the terms “distance” and “time”;...."
"It is the frame of reference in which the etalons are at rest....it is not privileged by nature, but it is privileged by the trivial semantical convention providing meanings for the terms “distance” and “time”;"
SR and LR are no different that any other area of physics, really. Take the notion of 212 degrees C, the "boling point," for example. We establish an etalon (standard of measurment) for it by specifying very precise and invariant conditions. Because the boiling point will vary with altitude, we must specify that (sea-level). Because it will change depending on the liquid, we must specify that we are talking about distilled water, not vinegar, or anything else. etc.
Both SR and LR establish etalons for time and distance, with certain specific conditions attached. The frame for them must be, for example, "at rest," and not moving. See what Szabo is getting at, here?
In the context of our earlier exchanges, I have said the "concept" of a yard (or an hour) does not change just because a particular yardstick (or clock) does. Another way to have said it would be to say the "etalon" (in place of "concept') does not change.
Likewise, the etalon for 212 degrees C does not change just because distilled water on top of Pike's Peak will "boil" at a different temperature than at sea level.
If a guy on top of Pike's Peak says he knows the temperature inside his pot just reached 212 C because the water just started boiling, he would be WRONG. We would not say: "You're right, of course. Every time you go up a foot, or an inch, the temperature changes, because there are an infinite number of standards for the "true" temperature, and that is because you perceive it differently. Whatever you perceive to be true is true and "real" and THAT, however variant, is THE standard for the measurement of temperature."
Did you watch those videos I posted? It amazing how, with some people, you can repeat the question, each time giving them the answer, even with hints given by stressing different words, and they will still have no clue:
Q:If you're going 80 miles per hour, how long does it take you to go 80 miles?
A: 10 minutes
Q (repeated): Listen closely, if you're going 80 miles* PER* hour, how long does it take you to go 80 miles?
A: 8 hours
Q: Once again, if you're going 80 miles per *HOUR,* how long does it take you to go 80 miles?
A: 2 1/2 minutes.
Amazing.
=== I just started looking at this and there are a few things that are not clear to me, but let me start with this:
1. "In all three frames, clock C reads 34.64, clock A reads 40. The prediction is the same using any inertial frame."
Assuming for the moment that this is accurate and relevant (which I don't, yet), as it relates to the H-K, the first question would be "so what?" If all three are wrong (not in accordance with what the clocks actually read), who cares?
The first frame (clock A) is the same frame as the one you think LR should use. Since you are arguing for LR, it would seems strange for you to claim it's wrong.
2. You say : "After clock C passes, it takes another 28.86 seconds on clock B (it's a simple algebra equation) before clock C catches up to clock A." Where does this come from. As I understand you, it takes only 17.32 seconds on B's clock for A to move (in his view) 10 ls away from from him. Presumably it would take another 17.32 seconds for A to move ANOTHER 10 ls away from him. So why should it take MORE (28.86 vs only 17.32) time to get the SAME distance to A (10 ls) when C is moving away (in his view) even faster?
This is just another example of selectively grabbing data from one frame and imputing to another. It's no wonder the results are self-contradictory.
I agree. Your taking the 10 ls from the frame of clock A and putting it into the frame of clock B is another example of selectively grabbing data from one frame and putting it into another. It's no wonder you get numbers that are self-contradictory.
However, one datum common to all frames is seeing clock B read 17.32 at the rendezvous point. So all frames know this happened.
Since A is moving at .5c relative to B for those 17.32 seconds (in B’s perspective), it moves 8.66 ls in B's perspective in that time. So, when C goes whizzing by, A has a lead of 8.66. Solve .8t = .5t + 8.66, and you get 28.86 more seconds on clock B, in which C moves 23.09 ls and A moves 14.43 ls.
3. You say: "Viewpoint of clock C: clock B is moving toward clock C at .8c, clock A at .5c" For one thing, as I uderstood your example, clock B would, at this point, be running AWAY from C, not toward him.
My viewpoint for clock C, just like for clocks A and B, runs from the start point. From the viewpoint of clock C, between the start and the rendezvous point, B is moving toward C.
"To use GR at all, space-time is interpreted as a four-dimensional manifold of negative curvature, IIRC, regardless of what you think."
I thought we were talking about SR, not GR. Within the framework of SR the "4 dimension" view just leads to physically absurd "explanations" of what's happening in the real world. You don't get those kind of absurdities using a 3 + 1 format.
When you said "Every description...", I did not realize you meant to include that limitation.
They say the mission that got us to the moon and back used ONLY newtonian notion of gravity (no GR).
There wasn't much need to align the NASA clocks to the moon capsules clocks within fractions of a second, presumably.
Assuming that GR predicts a couple of things better (like Mercury's orbit),
You forgot the GPS satellites. LR makes no provisions for the effects of gravity/acceleration on time dilation/contraction.
It's all still a matter of "interpretation." Al took a "field" view of GR, as I understand it, which is quite different than the "geometrical" interpretation, which you seem to be suggesting is the ONLY proper view.
They are not different views, just different descriptions of the same thing.
"If distance is defined as the path length of the shortest geodesic on a manifold of negative curvature, it can change." I really have no idea of what this is supposedly to be saying about objective, physical reality.
"So, let's say the distance does not change, but the length of the shortest path changes."
What is a "path?" in this sense? I gave an example of times when people might say taking the freeway is "shorter," but ONLY because they are confusing a measurement of TIME with a measurement of distance. Is that the kind of thing you mean?
A path is the amount of distance you use to go from point A to point B. The distance doesn't change, but the length of a path can change.
1. Viewpoint of clock A: it takes 20 seconds for B to move to the rendezvous point, and 20 seconds for C to move to the comparison point. 40 seconds pass on clock A.
2. "Clock C reads 34.64 compared to clock A reading 40."
3. "In all three frames, clock C reads 34.64, clock A reads 40. The prediction is the same using any inertial frame."
Again, assuming this is "true," can't you see that it contradicts the basic claim of SR that "each observer will "see" the other's clock as going slower?"
I don't see what is not true. Clock B tickes through 17.32 seconds before the rendezvous point, and 28.86 after, for a total of 46.18 seconds, compared to 40 for clock A. So, clock B measures fewer seconds on clock A than on itself. B measures even less time to pass on C (27.71 seconds).
If both A and B see A's clock as being 40 and B's as being 34.64,
Since they don't, I'll just ignore the part where you talk as if they do, unless there is somethig worth addressing.
Once again you have shifted to an LR viewpoint, all while claiming that you are expounding upon SR.
Every SR viewpoint is a potential LR viewpoint. They have the same mathematical tools.
I'm sure you will be unable to see this, so I'm really just talking to myself, I suppose.
I try to do you the kindness of not assuming you are too dense or stubborn to understand this. Think you can do that for me?
"It's not that I don't see your point of view, it's that I find it unnecessarily limiting."
Well, I suppose that from one perspective, rejecting rather than accepting, and condemning rather than extolling, fallacious sophistry is "limiting." And it would only be deemed "necessary" by someone who respects, and insists upon adherence to, acceptable standards of logic, I suppose.
We can each share unkind characterizations of each other’s positions, but I don't see how that leads to a better conversation.
The whole "you can't tell you're moving" narrative is so obviously at odds with fundamental physics that it really shouldn't require any "debunking." But, nonetheless, SR adherents will insist that it is physically "true."
Let's say you have determined the proper LR frame is clock A.
Let's says there are three clocks D, E, and F, with clock D in the same inertial frame as clock A. Clock E passes by D going at .5c, and 17.32 seconds later clock F passes D going in the exact same direction at .8c. You can perform all of the exact same calculations for this situation that I did for the framework of clock B above, and determine that when F passes E, F reads 34.64 and E reads 40. All of the calculations are the same, all of the numbers and results are the same. However, you want to say there is some essential difference between the calculation for D and the one for B. Regardless of wheter this is true, the reality is that all of the numbers are the same. In particular, even though E is really moving, it have 40 seconds compared to the combined 34.64 of B and C.
"Due to the popular/textbook literature on relativity theory, there is a widespread aversion to a privileged reference frame. However, like it or not, there is a privileged reference frame in both special relativity and classical physics. It is the frame of reference in which the etalons are at rest.
The empirical definition of a physical quantity requires an etalon measuring equipment and a precise description of the operation how the quantity to be defined is measured. For example, assume we choose, as the etalon measuring-rod, the meter stick that is lying in the International Bureau of Weights and Measures (BIPM) in Paris.
The reference frames of the etalons are not an inertial frame.
I think I have cited you to this "logical analysis" before. Perhaps you would like to read it some time and show, line by line, why it is false, it you deny his claims, eh?
He doesn't understand what an inertial frame is, or realize his etalons are not contained in one. Good enough?
He also denies that SR allows for an interpretation (like yours) that says there are no "real" changes in physical objects (clocks and rods, for example):
His saying this does not make it true.
Nick Percival, who has a degree in physics from Harvard
I read some of Nick's work. This is a quote.
Further, if we choose a “3rd party” inertial frame other than the ECI frame, we will not match the GPS data at all. Let’s pick an inertial frame that has the same constant velocity as the tangential velocity of a satellite at point A. Special Relativity would then predict that the velocity effect would make the satellite’s clock FASTER NOT SLOWER than the earth clocks below.
Mr. Percival seems to have missed that SR predicts that a GPS satellite clock in orbit would be predicted to "go slower" than a clock with the tangential velocity of a GPS satellite clock in orbit.
Physics uses, and has ALWAYS used, LR, not SR, when dealing with accelerating frames. LR has ALWAYS made accurate predictions in these cases while SR NEVER has.
Since they make the exact same predictions (as in my example), this will be hard for you to sensibly defend.
Eric, I'm going to try one more time get you to understand the difference between LR and SR.
You would need to understand SR much better to successfully explain the difference.
Keep in mind that neither SR or LR depend on the notion of "absolute rest" or an "ether." That seems to be one of your main misconception about the two.
You say that as if there is only one flavor of LR. Some flavors do indeed insist on the notion of absolute rest.
Boiled down, the fundamental difference is that LR retains absolute simultaneity while SR posits relative simultaneity.
Now, come up with a real-world scenario where this matters. Show me the calculation in LR, and then the calculations in SR, and how they differ at any point where direct, side-by-side comparisons can be made.
If you say the HK experiment or the GPS, I will respond that every mainstream source sees these results as a confirmation of SR/GR. Find something that has a direct comparison, where there could be a real difference in the numbers read.
Do you understand this? Do you dispute any of this?
I understand the passage, and dispute your interpretation.
Earlier I asked you if you thought that a "perfectly inertial" frame would "suddenly" change (from the way they are perceived in accelerating frames) the behavior of clocks. You didn't answer that question as I recall.
"All inertial frames give the same predictions. They do not force the clocks to do anything."
Did you find that sentence hard to understand for some reason?
To reinforce the point (I'm not sure that any amount of reinforcement will help in your case, but....): You say that SR "does not apply" in non-inertial frames. What you leave out (or completely forget about) is that even SR holds that acceleration is absolute (not "frame-dependent'). So, then, the natural question would be "what theory *does* apply in non-inertial frames?"
GR.
We have just seen the answer, which is, "Why, a theory of absolute motion (LR), of course." Which is, in fact, what the GPS uses and relies on, not SR.
If the GPS relied on LR only, it would fail, because LR does not allow for time changes from gravity/acceleration.
My turn to repeat:
"In the example in this post (the two directly approaching each other), has Jill seeing Jack's clock tick off two seconds for every one she sees tick off on her own clock. Jack sees two seconds tick off on Jill's clock for every second on his. You can run an experiment on this in a lab for sensitive enough clocks."
Do you understand this is what happens?
If both A and B see A's clock as being 40 and B's as being 34.64,
Since they don't, I'll just ignore the part where you talk as if they do, unless there is somethig worth addressing.
=====
"1. "In all three frames, clock C reads 34.64, clock A reads ."
Which one is it, this time?
Again, assuming this is "true," can't you see that it contradicts the basic claim of SR that "each observer will "see" the other's clock as going slower?"
"I don't see what is not true."
======
If you ever actually understand this, then maybe we can make some progress on this topic.:
"Once again you have shifted to an LR viewpoint, all while claiming that you are expounding upon SR."
"A path is the amount of distance you use to go from point A to point B. The distance doesn't change, but the length of a path can change."
Do you mean distance, or that distortion of distance relativists call"spacetime"
This is incoherent, as stated, if "lenghth of a path" is supposed to mean "distance," instead of sometime else, like time maybe.
=====
"He doesn't understand what an inertial frame is, or realize his etalons are not contained in one. Good enough?"
Hardly. You basically called Al an idiot, for supposedly not knowing what an inertial frame is and therefore not understanding the "true" (by your account) of the implications of SR. It's your standard response, generally revealing that you have no in-depth understanding of the topic.
His point is quite clear, and has nothing to do with "the earth," per se.
=====
"He also denies that SR allows for an interpretation (like yours) that says there are no "real" changes in physical objects (clocks and rods, for example):
His saying this does not make it true."
"No, of course not. He's simply doing a logical analysis of the topic. Perhaps you would like to read the article and see "why" he says it.
He doesn't actually say that SR doesn't "allow for it," but he does say, like Hogg, that the changes must be real, and not just illusory or just a "matter of perspective."
1."If both A and B see A's clock as being 40 and B's as being 34.64,
Since they don't, I'll just ignore the part where you talk as if they do, unless there is somethig worth addressing."
2. "In all three frames, clock C reads 34.64, clock A reads 40"
Which one is it, this time?
Let’s pick an inertial frame that has the same constant velocity as the tangential velocity of a satellite at point A. Special Relativity would then predict that the velocity effect would make the satellite’s clock FASTER NOT SLOWER than the earth clocks below.
"Mr. Percival seems to have missed that SR predicts that a GPS satellite clock in orbit would be predicted to "go slower" than a clock with the tangential velocity of a GPS satellite clock in orbit."
I have no idea what you're trying to say here, and obviously you don't understand what he's trying to say, as obvious and simple as it is.
1. You always want it both ways, don't you? "SR predicts that a GPS satellite clock in orbit would be predicted to "go slower" than a clock with the tangential velocity of a GPS satellite clock in orbit."
Just a minute ago you were insisting that SR makes exactly "no predictions" because it doesn't apply in non-inertial frames, eh?
2. In SR, the satellite's "frame," if viewed as inertial, would have to say that ALL other clocks are "going slower" than it.
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