Many theists believe there is an objective morality to be discovered. However, since you can't uncover such a morality in the same way you can lift a stone and find a pill bug, empirical systems are not use for this process. Instead, many rely on various works that they give implicit trust to, except when the advice of such books goes against their innate beliefs. Hence, we see homosexuals barred from military service, but don't see single women non-virgins barred in such a fashion, much less executed for being a single non-virgin.
Some attempt a seemingly more sophisticated approach of creating a morality based upon a few accepted notions and creating a formal system to reflect it. That's when you see people like the Maverick Philosopher examining the details on what their basic positions entail when examined in detail. Below the fold, I'll go into why I think this helps to pinpoint the inherent lack of objectivity in this construction of a moral system.
I'm not really concerned with the particular argument that Dr. Vallicella is making in his post, rather, I want to highlight what happens when he finds his argument is inadequate. In particular, he doesn't like the breadth of the conclusion of the argument, so he proposes a new starting point. That is, in creating this supposedly objective moral position, he changed his starting point to get the conclusion that he felt was the right one.
Now, I have no objections to this activity per se. In fact, this is one of the better advantages of operating strictly within a formal system. If the starting positions lead you to a situation you can't use, changing the starting positions is to be expected. If you are tracking the movements of ships on the surface of the earth, you don't pretend that the surface of the earth matches Euclid's parallel postulate; instead you assume that no lines (aka great circles) are parallel and use a Riemannian geometry. It will have the tools you need to look at ship movements around a globe.
However, the process of choosing these starting positions is strictly based on the conclusions you want to derive. That makes the starting positions arbitrary, and those positions will be carefully chosen so the results conform to the desired outcome. So, far from getting some objective morality that can be applied to all, you get a tailored morality designed to support a specific set of positions. Some of these systems, like natural law, were debated for hundreds of years before they were codified, and even then still generate disagreements around the edges.
When people come up with another method of knowing things that can exhibit certainty, reality, and demonstrability, that method of know may indeed lead to an objective morality. Until that time, there will be no such creature. All the construction within formal systems will not be able alter the shaky foundation upon which they rest.
Tuesday, December 7, 2010
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2,208 comments:
«Oldest ‹Older 401 – 600 of 2208 Newer› Newest»One Brow said: "Well, that depends on the "valid" reference frame. For example, both could be shortened by the exact same amount."
I said: His yardstick is not "ordinary." It is shortened and therefore defective.
Unless yours is the one that is shortened.
Why do you keep saying this? It is irrelevant and meaningless, like saying "You're right, unless you're wrong."
Mine will NOT be shortened, relative to his, if I'm not the one who has been accelerated to a higher speed. Acceleration is absolute. That's what SR tells us. SR does NOT tell us that "you can't know" although Al tried to claim that at first, causing mass confusion amongst some ever since.
The earth orbits the sun, unless the sun orbits the earth. Aint that special?
It's nighttime where I am right now, unless it's day.
The moon is made of green cheese, unless it isn't.
What is the significance of such "observations?"
One Brow said: "I'm not sure what you mean by "right" and "equally valid", and you have not offered a direct defintion of what you mean. The EEP says you can't distinguish between different frames under certain conditions."
If by EEP you mean Einstien Equivalence Principle, that is not it. That was a Machian postulate he temporarily (like for about 20 years) adopted. He did have hypothetical examples involving such notions, but those are not the principle.
allieo made the passing observation, when explaining his tranformations, that a person in a windowless ship would not know if he was moving, so long as his speed and direction was constant. He was basically explaining how inertial motion worked, and why a ball doesn't land far away from you when thrown straight up if the earth is moving in orbit. It was not a "principle" on which his transformations were based, and it isn't for SR either.
It is not "part of the theory." It is the starting point for a Liebnitzian, Machian, positivistic philosophy, can't you see that? SR does NOT tell you that you there is no way of knowing whose instruments have shortend. It shows you how you can tell (see who has accelerated, who ages slower, etc.).
You have to go "outside" medical theory to know if you have a cold, so what. That's true with EVERY theory in EVERY case, can't you see that? You act like this is unique or unusual. I can't have a theory about what causes fire, but that theory won't, and can't, tell me if a house on Flatbush Avenue in Brooklyn is burning right now. So what?
If I throw a ball, it has been accelerated, not me. That's taken for granted. We all know it. Physics presupposes it. What purpose does it serve to say that it "could be" that I am moving away from the ball, not it from me?
Just the purpose of being willfully contrary, obstinate, and ignorant, that it?
One Brow said: "I am someone who sees the whole over empahsis on the parts. That doesn't makes the parts "the same" thing, but it clarifies what their limitations are withing the whole.
From the Encyclopedia Britannica:
I didn't see anything in the article that would dispute the notion of science being a unified process that combines empirical and theoretic methods."
Did you see anything which distinguishes empirical observation from scientific theory?
The failure/refusal to recognize and acknowledge significant distinctions does not make one "holistic." or wise. It's like saying all behavior (e.g., slitting a guy's throat in an alley for the 37 cents he has in his pocket) is just "behavior," and that it's senseless to speak of "right" or "wrong" behavior, because it's all "just behavior."
Do you dispute this?:
"A theory may be characterized as a postulational system (a set of premises) from which empirical laws are deducible as theorems."
Do you dispute this?:
"Thus, it is evident that theories are imaginative constructions of the human mind—the results of philosophical and aesthetic judgments as well as of observation—for they are only suggested by observational information rather than inductively generalized from it."
You were going to write a topic about "inductive" logic. Do you agree that scientific theories are NOT a product of inductive logic? The so-called "empirical laws" are inductively created, but not the postulated axioms which generate a "theorem" that matches "empirical laws."
Scientific theories, like Euclidean geometry, formulate postulates from which the phenonmena can purportedly be deduced (not induced).
One Brow said: "One Brow said: "Well, that depends on the "valid" reference frame. For example, both could be shortened by the exact same amount."
Arbitrary and imaginative "reference frames" can't, and don't, change facts or in any way affect them. They're irrelevant. If I load up a ship with rocket fuel and blast it off into space, it has accelerated, relative to me, (and not me, relative to it) REGARDLESS of whether anyone else knows it and REGARDLESS of whether they want to pretend they're standing on the sun, or some such supposition. How someone else might "see" it is irrelevant.
You still can't see this?
One Brow said: "Mathematical theories get abandoned when they get boring or stale. Scientific theories get altered when then stop agreeing with experiemental results, no matter how interesting or boring they may be."
The difference is supposedly when and why they are "abandoned?" You're not even addressing the issue. If Euclidean geometry stops accurately telling me the angles at which I must cut my lumber when framing a roof with a 7/12 pitch, I might stop using it. I was bored with roof trusses a good while back, but that has nothing to do with the usefulness of geometry.
Noting recurring regularities in nature, such as the fact that the seasons recur in a regular manner, the fact that the time period for one oscillation of a pendulum is constant, regardless of length or angle, the fact that objects "always fall" when unsupported, and in fact fall with the same rate of acceleration, regardless of mass, etc., is certainly a worthwhile thing to do. Call it "science" if you want. But it is NOT the creation of a scientific theory. It is merely an observation of regularities in nature. Via induction, one may generalize such observations as matters of "empirical law." Newton actually had no "theory" of gravity, he simply had a formula which fit the observable, recurrent facts.
Joining 3 lengths with ratios of 3, 4, and 5 on a plane surface will give you a right angle as a matter of empirical law. No need for Euclid, there. No need of a "theory," it just happens regularly.
What Euclid did with a known way to produce a right angle, was not really different than what Al did with the known fact that "things fall." Granted, Al's math was much more complicated, but, still....
Kinda funny that what presumably seems intuitively obvious (and certainly not theory-laden) to you never even crossed the minds of brilliant analysists like Newton, Gallieo, etc. For some damn reason they didn't immediately say that a ball fell to the ground when dropped from a tower because "space behaved as though it is curved."
I guess they just aren't as observant as you, eh, Eric? Any fool can see....
"I hold that space cannot be curved, for the simple reason that it can have no properties. Of properties, we can only speak when dealing with matter filling the space. To say that in the presence of large bodies space becomes curved, is equivalent to stating that something can act upon nothing. I, for one, refuse to subscribe to such a view" -- Nikola Tesla
Principles, like Tesla's there, aside, maybe nobody "saw" how obvious it is that space "behaves like it's curved" because it really aint noticeable, eh?:
"The curvature of space alone has almost no effect on the movement of objects...With the exception of only the most extreme cases (black holes), space is very, very close to flat. For example, the total stretching of space due to the Earth amounts to less than 1 cm."
http://www.askamathematician.com/?p=4448
Less than one cetimeter caused by the whole earth, eh? Kinda hard to "see" that--maybe you need some theory to make that kinda claim.
So what does cause gravity, then? Accordin to this guy:
"...anything that moves forward in time will find its trajectory pointing down slightly. This takes the form of downward acceleration. This acceleration (time pointing slightly down) is entirely responsible for the motion of the planets, and every other everyday experience of gravity."
So, it's "time" that causes gravity, eh? Heh, talk about math taking on a "life of it's own," ya know?
An ancient greek religious/mystical sect was the Pythagoreans (of hypotenuse fame). They "worshipped" numbers, as numbers, and attributed all kinds of transcendental qualities and powers to numbers, such as the power of prophecy. For them, numbers were the ultimate reality, and all the substratum for all existing things.
It seems like there are many pythagoreans, often masquerading as theoretical physicists, astrophysicists, and cosmologists still extant today, if ya ax me.
Mine will NOT be shortened, relative to his, if I'm not the one who has been accelerated to a higher speed.
Here is the initial scenario you offered: "Suppose that an object is approaching me at the rate of about 350,000,000 mph (about half the speed of light)." You said nothing about that object having been accelerated, or you not accelerated. I agree that if the object in question was accelerated to .5c, it would have the shorter yardstick, although I disagree that this make the yardstick defective.
Acceleration is absolute. That's what SR tells us.
Technically, acceleration does not play into SR at all. You can use SR and the notion of acceleration to solve certain problems not solvable exclusively by SR, but but solve them without invoking GR.
If you disagree, please point to one equation in SR that takes acceleration into account.
It was not a "principle" on which his transformations were based, and it isn't for SR either.
The notion of an inability to deteect inertial motion is a fundamental part of the EEP.
You have to go "outside" medical theory to know if you have a cold, so what. That's true with EVERY theory in EVERY case, can't you see that?
I'm quite aware of that. Since you can also see that, why do you have an issue with saying you need to go outside SR to resolve the twin scenario?
If I throw a ball, it has been accelerated, not me. That's taken for granted. We all know it. Physics presupposes it. What purpose does it serve to say that it "could be" that I am moving away from the ball, not it from me?
I don't remeber the details on how the EEP works into relativity, but I do remember it is essential for deriving the equations.
Did you see anything which distinguishes empirical observation from scientific theory?
I can distinguish even numbers from odd numbers. That doesn't mean the counting process consists of two widely separated, distinct notiuons of counting an odd number and counting an even number.
The failure/refusal to recognize and acknowledge significant distinctions does not make one "holistic." or wise. It's like saying all behavior (e.g., slitting a guy's throat in an alley for the 37 cents he has in his pocket) is just "behavior," and that it's senseless to speak of "right" or "wrong" behavior, because it's all "just behavior."
The insistence on treating different aspects of a single process as being irreconcilable does not make one analytic or precise.
Do you dispute this?:
No.
You were going to write a topic about "inductive" logic. Do you agree that scientific theories are NOT a product of inductive logic?
No. In fact, I think that the claim that using empirical results to inform the contructions of the mind is not a case of inductive reasoning to be quite a curious claim.
The so-called "empirical laws" are inductively created, but not the postulated axioms which generate a "theorem" that matches "empirical laws."
While you could point to some differences in the induction, I find both to be examples of inductive thinking.
Scientific theories, like Euclidean geometry, formulate postulates from which the phenonmena can purportedly be deduced (not induced).
Scientific theorists use inductively created posulates and the form of thinking prevalent in formal systems to make predictions, just like experiementers use use empirical laws determined by inductively created postulates and the form of thinking prevalent in formal systems to make predicitons.
The difference is supposedly when and why they are "abandoned?"
That's one difference that illustrates the differences in their natures. Did you want an exhaustive list?
If Euclidean geometry stops accurately telling me the angles at which I must cut my lumber when framing a roof with a 7/12 pitch, I might stop using it. I was bored with roof trusses a good while back, but that has nothing to do with the usefulness of geometry.
I don't think there are any mathematicians who specialize in developing Euclidean geometry, producing new theorems, etc., even though we both agree it is useful. Certainly there are not as many as in, for example, large cardinal theory.
What Euclid did with a known way to produce a right angle, was not really different than what Al did with the known fact that "things fall." Granted, Al's math was much more complicated, but, still....
Euclid started with ideas that have no reality by their nature (point, line, etc.). Einstein started with idealized extensions of real, measured phenomena.
Kinda funny that what presumably seems intuitively obvious (and certainly not theory-laden) to you never even crossed the minds of brilliant analysists like Newton, Gallieo, etc.
That is because I can stand on the shoulders of the men who stood on the shoulders of the men ... who stood on the shoulders of the men who stood on Newtons shoulders, and even more so for Galileo. It says nothing special about me, certainly.
Less than one cetimeter caused by the whole earth, eh? Kinda hard to "see" that--maybe you need some theory to make that kinda claim.
Or a much more massive object than the earth.
So, it's "time" that causes gravity, eh? Heh, talk about math taking on a "life of it's own," ya know?
Maybe.
One Brow said: "Technically, acceleration does not play into SR at all. You can use SR and the notion of acceleration to solve certain problems not solvable exclusively by SR, but but solve them without invoking GR.
If you disagree, please point to one equation in SR that takes acceleration into account."
That's the whole point. SR doesn't provide any equations for acceleration because acceleration is absolute, not "relative," and SR doesn't apply to accelerating objects.
As for previously accelerated objects, thereafter travelling at a uniform speed, in a straight line, it deals with them just fine, and tells you that the previously accelerated object will have slower time. If you're lookin for equations describing that, just go the the wiki page for the twin paradox, eh?
One Brow said: "The notion of an inability to deteect inertial motion is a fundamental part of the EEP."
The "equivalence principle" as I understand it, has two forms, and merely deals with the supposed "equivalence" of gravity and acceleration.
The "weak" form merely says, as Newton did, that gravitational mass equals inertial mass. This is actually the "Galliean" equivalence principle. Wiki says: "The principle does not apply to physical bodies, which experience tidal forces, or heavy point masses, whose presence changes the gravitational field around them. This form of the equivalence principle is closest to Einstein's original statement: in fact, his statements imply this one."
So it doesn't apply to physical bodies, eh?
Al went a step further, and claimed that: "The outcome of any local experiment (gravitational or not) in a freely falling laboratory is independent of the velocity of the laboratory and its location in spacetime." This is the EEP.
As noted by wiki, it is problematic. " For example, "The Einstein equivalence principle has been criticized as imprecise, because there is no universally accepted way to distinguish gravitational from non-gravitational experiments (see for instance Hadley[11] and Durand[12])...
Modern scientists have since developed a "strong equivalence priniciple," which allows strictly limited gravitational, as well as non-gravitational, experiments to be included, but that's not really the EEP.
In any event, the Einstien equivalence principle, such as it is, simply applies to gravity and its supposed "equivalence" to acceleration. It has nothing to do with SR, per se.
This was important to him because:
"From this principle, Einstein deduced that free-fall is actually inertial motion. Objects in free-fall really do not accelerate, but rather the closer they get to an object such as the Earth, the more the time scale becomes stretched due to spacetime distortion around the planetary object (this is gravity)...So the original equivalence principle, as described by Einstein, concluded that free-fall and inertial motion were physically equivalent. This form of the equivalence principle can be stated as follows. An observer in a windowless room cannot distinguish between being on the surface of the Earth, and being in a spaceship in deep space accelerating at 1g. This is not strictly true, because massive bodies give rise to tidal effects (caused by variations in the strength and direction of the gravitational field) which are absent from an accelerating spaceship in deep space.
Although the equivalence principle guided the development of general relativity, it is not a founding principle of relativity but rather a simple consequence of the geometrical nature of the theory."
So, they say, it is neither a "founding principle" of GR, nor is it even "true."
A couple of other things worth noting: "Einstein combined the equivalence principle with special relativity to predict that clocks run at different rates in a gravitational potential, and light rays bend in a gravitational field, even before he developed the concept of curved spacetime." The bending of lightrays is NOT a function of curved space to begin with--it is the variable speed of light or, alternatively, the supposed "curvature" of time, not space. Spacetime supposedly "curves, but as noted in one of the posts above, it is the "time" element, not the "space" element, which supposedly accounts for gravity (except near black holes).
http://en.wikipedia.org/wiki/Equivalence_principle
Everything in that last post is just a sidetrack, though. In my previously posts, I was NOT referring to the EEP when talking about the supposed (but erroneous) "equilavence" of each perspective of two observers moving relative to each other. That "principle" has nothing to do with SR as a physical theory, but it only an extraneous philosophical claim.
I just referred to a "last post" which no longer appears and presumably got swallowed by your spam filter. Chance are, now the post with the reference to the "last post" will also disapper.
One Brow asked: "I'm quite aware of that. Since you can also see that, why do you have an issue with saying you need to go outside SR to resolve the twin scenario?"
Because you appear to be asserting it to imply that SR does not predict the effects of acceleration, even if the theory does not purport of be a catalog of every accelerated object in the past, present, and future.
My question is, why do you assert it as somehow relevant? I's sure that you think it's relevant due to the Machian "relational" philosophy to want to profound. But the point is, it aint relevant to SR, as a physical theory.
Edit: "I'm sure that you think it's relevant due to the Machian "relational" philosophy you want to propound."
Got a little hasty there, eh?
One Brow said: "The insistence on treating different aspects of a single process as being irreconcilable does not make one analytic or precise."
Nice strawman, there, eh, Eric? I have never said that experimental science and/or raw empirical observation were "irreconicilable" with theoretical science. I have simply been trying for months to get you to distinguish the two, so that we can analyze your claim that scientific theory is "completely different" from formal theories which may be developed with respect to geometry, ethics, or any other topic.
The theory is NOT observation, and it is NOT the attempt to experimentally falsify the necessary implications of the theory. The theory is it's own thing, just like theories of morality, of economics, or of plane geometry are.
I said: "The so-called "empirical laws" are inductively created, but not the postulated axioms which generate a "theorem" that matches "empirical laws."
One Brow said: "While you could point to some differences in the induction, I find both to be examples of inductive thinking...
Euclid started with ideas that have no reality by their nature (point, line, etc.). Einstein started with idealized extensions of real, measured phenomena.
You seem to have a notion of what "inductive reasoning" is that differs from what I take to be the common view, Eric. A few observations:
1. Popper, for example, took the position that there is no such thing as "inductive logic" and said that every inference, of every kind, is in fact an instance of deductive logic.
2. Euclid started with known facts and measurements too. Anyone can look for constant relationships in spheres, circles, rectangles, squares, etc. and this was done by Euclid. He did not just start in a vacuum. The pythagorean theorem was know, as a matter of empirical fact, long before Pythagoras "proved" it (which was long before Euclid creates his postulates to "deduce" these known facts).
3. Einstien, for one, disagrees with you. He was very emphatic in asserting that his theories were NOT the result of empirical observation, but rather freely and creatively produced by an inventive mind. He said the same of all other theories, too, of course.
But here's the general process:
First, regularities are noted, via empirical observation. Then, later, someone creates a "hypothesis" which, if true, would necessarily imply the known regularities. The observations don't "create the theory." The Indians, Egyptians, Persians, and many others had put geometrical relationships to good practical use for hundreds or thousands of years before there was any formal "theory" from which those known relationships could supposedly be deduced.
The mere fact that you are trying to theoretically explain known phenomena does NOT make the concoction of a set of postulates "empirical."
Native Americans supposedly had only a very few terms to express quantities, something like a word for "one" a word for "two" and a word (such as "many") for all other quantities. If they saw 20 buffalo, that was "many" buffalo, same as if they saw 3 or 3,000. But there were still actually 3, or 3,000, or whatever actually there by definition of our arithmetical theories. Seeing 20 buffalo doesn't "give" you the notion of "20" as a numerical quantity.
But, undoubtedly, arithmetic systems relied on observable quantities when developed. Same with any theory, really.
As I'm sure you know, a major "theoretical" break-through in numerical systems came when some arab decided to treat the quantity of "zero" as it's own number. Of course this would "correspond" to the familiar empircal circumstance when there are no ducks on the lake, as opposed to 2, 3, or 4 ducks. That doesn't make the absence of ducks the "empirical" basis for the numerical concept of "zero," know what I'm sayin?
Inductive logic is often described as forming a general conclusion from an exposure to special cases where it has been true.
I might say, for example, that in all known cases, unsupported objects fall toward earth. I might call this phenomenon "gravity" and I might generalize it by claiming that is it ALWAYS true, and hence have myself a "universal (empirical) law of gravitation."
But that would NOT be a "theory of gravity," One hypothetical premise allows you to form no secondary conclusions. If your "hypothesis" is merely that "things always fall," all you can "deduce" from that is that "things always fall."
To have scientific (explanatory) theory of gravity, you must create at least one additional postulate, along the lines of "things always fall because....."
The fact that one of your postulates is inductively derived does not mean the additional postulates are also inductively generated. In fact, they never are.
I said: "Less than one cetimeter caused by the whole earth, eh? Kinda hard to "see" that--maybe you need some theory to make that kinda claim."
You responded: "Or a much more massive object than the earth."
What I've been addressing here, Eric, is your incredibly naive denial that the statement that "space behaves as if it's curved" is NOT theory-laden. Of course it is, in an extreme degree. As you often do with your preferred conclusions, you tend to act as though they are simple products of empirical observation. They are not. They're not even accurate, from what I can tell.
If the earth theoretically "stretches" space by a total of 1 cm, how in the hell would the "curvature of space" explain why a ball falls straight down from a 20-story tower at an ever-increasing rate of speed?
Again, it is "spacetime" (a mathematical notion that can also be applied to Newtonian mechanics) not "space" that is said to be "curved" (in a geometrical/mathematical sense).
Don't bring up (theoretical) conditions that you speculate may exist "elsewhere" to explain to me why a ball might appear to follow a curved path if I hit it with a bat here on earth. It that because "space is curved?" No one seems to think so, except you.
Of course, the "downward pointing of time" (curved time) as a "cause" of gravity is just as abstract and just as derived solely from mathematical (geometrical) models as is the claim that curved space causes gravity.
The reification of purely conceptual notions such as "space" and "time" amazes me. The Phythagoreans thought numbers had spatial extension and were sort of a "atom" from which everything else was composed. Numbers, for them, were "things" in the literal, physical sense of the word. Same with "space and time" for relativists. They can't see the forest for the trees.
What possible sense (other than a mystical one) could it make to say "time causes gravity?" It's an utterly empty notion in a physical, as opposed to mathematical, sense. It "explains" nothing as a physical matter, yet these mathematicians have no problem glibly stating that "This acceleration (time pointing slightly down) is entirely responsible for the motion of the planets, and every other everyday experience of gravity," and apparently being satisfied that they have "explained" everything.
And you, of all people, want to claim that your preferred geometry is "true" while at the same time trying to claim that geometry, as a formal system, has no relation to "truth." Which is it?
One Brow said: "Euclid started with ideas that have no reality by their nature (point, line, etc.). Einstein started with idealized extensions of real, measured phenomena."
This isn't right either. In "reality" we all knnow what a line and a point is. Granted, Euclid "idealized" these notions for formal purposes, but, in "reality," imperfect lines can be established (e.g., by stretching a string tautly between two points)as can "points" (e.g. by putting a painted "dot" on the floor). Time, distance, and, therefore speed, which Einstein dealt with in SR, implicitly assume the validity (and "reality") of points and lines, so you can't claim that he dispensed with these "unreal" notions.
Eric, you rountinely seem to point out some supposed "flaw" in any position you disfavor, usually followed by a peremptory dismissal of that position, without taking the time you see if, in fact, your "favored" positions are not themselves imbued with the same so-called "flaws."
I said: "I might say, for example, that in all known cases, unsupported objects fall toward earth. I might call this phenomenon "gravity" and I might generalize it by claiming that is it ALWAYS true, and hence have myself a "universal (empirical) law of gravitation."
But that would NOT be a "theory of gravity,"
And this is the precise problem involved in trying to interpret Gould (and others) as if they were talking about an actual theory when they claim that "evolution" is just a well established as "gravity."
As empirical laws, sure. As theories? Well, all theories of gravity, as well as those of evolution, are certainly subject to reasonable (non-"perverse") debate.
We discussed the particular Gould "fact vs theory" passage several times. To me, in is quite clear that he is NOT saying, and in fact goes out of his way to deny that he is saying, that "theories" are certain. He does say that not even so-called "facts" are absolutely certain, but that they are so well accepted that it would be perverse to deny them. It's hard to reasonably deny that "things fall" in the everyday meaning of "fall."
But YOU insist that he is saying a particular THEORY of evolution (for which you go so far as to reduce to "common descent") cannot be debated. Why? Because you consistently refuse to acknowledge nature of a scientific theory, as opposed to an "empirical law."
I have a sister who always "justifies" her desires not to do thing X, or thing Y, by finding some possiblity, however seemingly remote, that some undesirable event could occur in the event one were to actually undertake action X or Y. Maybe you know the type. If they can point out one thing that could "possibly" be wrong with a course of action, that's the end of the discussion.
The truth is, that's never her reason for rejecting action X or Y to begin with, even if she doesn't consciously know it. Invariably she has some emotional, intuitive and/or irrelevant motivation not to do X, or Y. She is just unable, or unwillingly, to disclose and articulate the "true" reasons for her rejection. She thinks, and wants you to think, that her decision-making process is rational and objective, but she really aint foolin nobuddy, except maybe her own damn self.
Of course, the exact same frivilous procedure could be used to reject any course of action which she does advocate undertaking. She just doesn't employ it for things she wants to do to begin with.
You kinda remind me of her, with your "could be a flaw, so end of discussion" approach to rejecting things you don't like, and thereby continuing to faithfully embrace the things you do like. The whole "some rational people think the moon is made of green cheese" response to information which you want to reject is one of the more extreme examples to which I am referring.
Back to the EEP (gravity = acceleration) and the "motion is strictly relational" propositions for a minute:
It's quite a stretch to go from saying that a person going downsteam on the Mississippi in a steamboat would not know he is moving while sleeping in his bunk to saying that, while standing on deck watching the trees and towns go by, he would not know if the trees were moving (previously accelerated) relative to him rather than him relative to the trees. This is just as absurd as saying that when he leaves his bunk, he has no way of knowing if the bed is moving away from him, instead of him from it. That is NOT the "principle of relativity."
One makes perfect sense, the other is prima facie absurd. Gailleo never made such an absurd claim, and there was no need for Al to try to do so either. But, absurd or not, the claim is irrelevant to physics and it's laws, which do NOT depend on whatever subjective notion a given individual might happen to entertain.
I just can't see how it's relevant to talk about what a person might "think" if you strictly limit the information available to him and then cut of his means of obtaining it. It has nothing to do with physics. GR itself freely grants that "gravitation" must involve mass, and that it is a quite different phenomenon in FACT, even if not in subjective perception, from constant acceleration far from all massive bodies. The supposed "equivalence" between the two is strictly subjective at best, not objective; strictly mathematical, not physical.
The type of subjectivist characterization of "reality" suggested by the EEP is astonishingly misleading. If true, there simply could be no physics. There could, of course, still be heaps of metaphysical mumbo jumbo, but....
You should remember that Al reversed notions of inertial motion with a particular end, of particularly powerful appeal to him, in mind. He wanted to claim that acceleration is relative. He was convinced he succeeded when he published his final theory, but was mistaken.
Good things may have come from GR, but NOT because gravitional effects are physically (objectively) indistinguishable from acceleration.
True, or false, ya figure:
If one does not have an absolute, physically quantified, definition of "tall" then it is meaningless and nonsensical to say John is taller than Mike.
A bumble bee does a dance for the tribe to communicate the location and existence of nourishment which he has discovered to his homeys. I have no doubt that the motions involved in this dance could be ploted on graph paper, whether in "spacetime" or simply space and time.
But who in the hell would suggest that the slope of the lines on the graph paper is what "causes" the other bees to fly straight to the discovered treasure, eh?
One Brow said: "I agree that if the object in question was accelerated to .5c, it would have the shorter yardstick, although I disagree that this make the yardstick defective."
Assume that we ran across a tribe of people who routinely tortured, sodomized, and then cannibalized their own 3 year old children. Most of us would say such behavior is warped, or distorted, or unnatural, or wrong, or demented or worse.
The cultural relativist would agree that this standard of behavior is "different" from ours, but would deny that it is "wrong" or that any other type of perjorative characterization of the behavior is appropriate. Then he might congatulate himself for his cosmopolitan, sophisticated, and unbiased analysis.
I still would not agree. Nor would I agree that a person's refusal to acknowledge any standards would nullify all standards.
If the accelerated party's measurments have "really" shrunk, then they are defective. Assuming he knows, by virtue of the g-forces he experienced while being accelerated, etc., that he has been accelerated, then he will also KNOW that his measurements are no longer reliable, and would convert them to his pre-acceleraton equivalents rather than insist that they are not deviant, but rather "correct."
That's the whole point. SR doesn't provide any equations for acceleration because acceleration is absolute, not "relative," and SR doesn't apply to accelerating objects.
Glad we agree.
The "equivalence principle" as I understand it, has two forms, and merely deals with the supposed "equivalence" of gravity and acceleration. ... Al went a step further, and claimed that: "The outcome of any local experiment (gravitational or not) in a freely falling laboratory is independent of the velocity of the laboratory and its location in spacetime." This is the EEP.
Did you notice the "velocity" in there? That the part that refers to inertial conditions.
In any event, the Einstien equivalence principle, such as it is, simply applies to gravity and its supposed "equivalence" to acceleration. It has nothing to do with SR, per se.
Initial SR assumptions (rough approximations):
1) The speed of light is the same for any observer.
2) Identical experiments in different inertial conditions have identical results.
Initial GR assumptions (rough approximations):
1) The speed of light is the same for any observer.
2) Identical experiments in different inertial conditions have identical results.
3) Identical experiments in identically acceleratiing conditions have identical results.
This is one reason SR is actually a special case of GR.
Although the equivalence principle guided the development of general relativity, it is not a founding principle of relativity but rather a simple consequence of the geometrical nature of the theory."
So, they say, it is neither a "founding principle" of GR, nor is it even "true."
Historically, the EP precedes the use of differential geometry by better than five years, and the EP does specify the need for a uniform gravitational field, so it is true while referring to an idealized situation (much as many earlier laws of physics relied on frictionless media and objects that did not absorb heat upon impact.
The bending of lightrays is NOT a function of curved space to begin with--it is the variable speed of light or, alternatively, the supposed "curvature" of time, not space.
http://en.wikipedia.org/wiki/History_of_general_relativity
Also the deflection of light by massive bodies was predicted. ... But the actual value for the deflection that he calculated was too small by a factor of two, because the approximation he used doesn't work well for things moving at near the speed of light. When Einstein finished the full theory of general relativity, he would rectify this error and predict the correct amount of light deflection by the sun.
Only after you use the the equations that make space act like it is curved do you get accurate prediciton for the bending of light. Time dilations effects are insufficient.
That "principle" has nothing to do with SR as a physical theory, but it only an extraneous philosophical claim.
Every theory that generates the equations of SR uses some version of the intertial equivalence principle, or some assumtion that is a superset of it, to produce the equaitons. That does include LET.
Because you appear to be asserting it to imply that SR does not predict the effects of acceleration, even if the theory does not purport of be a catalog of every accelerated object in the past, present, and future.
I acknowledge and understand that SR can be used, with other physics, to predict the effects of acceleration.
My question is, why do you assert it as somehow relevant?
I think it's important to be clear which parts of our understanding come from which parts of the theories we use. That makes it easier to know which parts of our understanding will need to be changed when those theories are revised.
Nice strawman, there, eh, Eric?
I wanted to make it the equal of yours.
The theory is NOT observation, and it is NOT the attempt to experimentally falsify the necessary implications of the theory. The theory is it's own thing, just like theories of morality, of economics, or of plane geometry are.
While I don't want to argume from definitions, I'm hoping the one from American Heritge will clarify rather than confuse.
1. A set of statements or principles devised to explain a group of facts or phenomena, especially one that has been repeatedly tested or is widely accepted and can be used to make predictions about natural phenomena.
2. The branch of a science or art consisting of its explanatory statements, accepted principles, and methods of analysis, as opposed to practice: a fine musician who had never studied theory.
3. A set of theorems that constitute a systematic view of a branch of mathematics.
4. Abstract reasoning; speculation: a decision based on experience rather than theory.
5, A belief or principle that guides action or assists comprehension or judgment: staked out the house on the theory that criminals usually return to the scene of the crime.
6. An assumption based on limited information or knowledge; a conjecture.
When I refer to a scientific theory, I am usually thinking of it in terms of 1) or 2), in no small part because the blogs I tend to read in which scientists do the writing portray the notion of theory that way. You seem to be leaning more to 3). Under either 1) "repeatedly tested" or 2) "methods of analysis", in science the observations and attempts to falsify are important parts of making it a theory to begin with. Scientific theories have formal aspects, and we can certainly discuss those formal aspects separated from the other parts fo the theory, but we would then only be discussing a part of the theory, and not the theory as a whole.
Both 2) and 3) can apply to purely formal systems. The difference between 2) for scientific theories and 2) for formal theories is the "methods of analysis". The method of analysis for a formal system is primarily a formal calculus, such as classical logic, and the assurance that the results are mutually consistent and desirable. The method of analysis for a scientific theory is experimentation, and the assurance that the results are observable and reflect an underlying reality.
You seem to have a notion of what "inductive reasoning" is that differs from what I take to be the common view, Eric.
Well, the common view among people who try to formalize inductive thinking into an inductive logical system.
2. Euclid started with known facts and measurements too.
Euclid was looking for a useful model that would comport with known facts and measurements. That was his goal, and I have no doubt he revised his model many times to reach the goal he desired. However, his inital ojects did not include a single empirical phenomenon.
3. Einstien, for one, disagrees with you. He was very emphatic in asserting that his theories were NOT the result of empirical observation, but rather freely and creatively produced by an inventive mind.
Yet, he started with empircal observations and phenomena (speed of light, experimental results).
The mere fact that you are trying to theoretically explain known phenomena does NOT make the concoction of a set of postulates "empirical."
I agree.
But, undoubtedly, arithmetic systems relied on observable quantities when developed. Same with any theory, really.
Please identify the observalbe quantities used in, for example, large cardinal properties.
That doesn't make the absence of ducks the "empirical" basis for the numerical concept of "zero," know what I'm sayin?
I agree completely. Of course, "0" is a mathematical construct, not a scientific construct.
I might say, for example, that in all known cases, unsupported objects fall toward earth. I might call this phenomenon "gravity" and I might generalize it by claiming that is it ALWAYS true, and hence have myself a "universal (empirical) law of gravitation."
But that would NOT be a "theory of gravity,"
I agree.
The fact that one of your postulates is inductively derived does not mean the additional postulates are also inductively generated. In fact, they never are.
It's impossible to use two or different, inductively derived postulates in a single scientific theory? It's possible, but has never actually been done? What is "never" supposed to mean here?
Which of the two postulates of SR mentioned above (constant speed of light, inertial equivalence) do you think was not generated/confirmed inductively before the creaton of SR?
What I've been addressing here, Eric, is your incredibly naive denial that the statement that "space behaves as if it's curved" is NOT theory-laden. Of course it is, in an extreme degree.
Only to the same degree that any other claim of the general behavior of objects is theory-laden. If you are saying that the conservation of mass-energy it theory-laden, that "the pressure of a gas increases as the temperature increases" is theory-laden, etc., then I'll acknowledge that term applies to the notion of space curvature.
If the earth theoretically "stretches" space by a total of 1 cm, how in the hell would the "curvature of space" explain why a ball falls straight down from a 20-story tower at an ever-increasing rate of speed?
By the cumulative effects of the curvature being applied constantly.
Don't bring up (theoretical) conditions that you speculate may exist "elsewhere" to explain to me why a ball might appear to follow a curved path if I hit it with a bat here on earth. It that because "space is curved?" No one seems to think so, except you.
Ask any physicist who accepts GR.
The reification of purely conceptual notions such as "space" and "time" amazes me.
In what medium do spacelike and timelike differences exist, if not spacetime? For that matter, earlier you were (incorrectly) expressing the view that time dilation alone accounted for the bending of light. If time is just a concept with no external reality, how can dilating it bend light?
I do agree we need to be cautious about thinking of space and time as if they are concrete things, because if they are concrete, it is in a very different way than a chair, for example, is concrete. However, if there are empirical differences in space and/or time postions between two phenomenon, than those differences are not purely conceptual. So, I disagree that it is impossible for something we can meusre to have an effect on other things.
What possible sense (other than a mystical one) could it make to say "time causes gravity?" It's an utterly empty notion in a physical, as opposed to mathematical, sense. It "explains" nothing as a physical matter, yet these mathematicians have no problem glibly stating that "This acceleration (time pointing slightly down) is entirely responsible for the motion of the planets, and every other everyday experience of gravity," and apparently being satisfied that they have "explained" everything.
I don't think there are more than a handful of people who think "everything" is explained, and fewer still that are scientists. As for what is explained by saying time pointing down causes acceleration, again I agree we should be not be assigning time the same type of existence that we assign mass. I disagree that means we can assign it no form of empircal existence at all.
And you, of all people, want to claim that your preferred geometry is "true" while at the same time trying to claim that geometry, as a formal system, has no relation to "truth." Which is it?
???
Euclidean geometry is stuffed to the gills with a variety of truths, as any well-constructed formal system should be. Truth in a formal system is determined within the system.
My "preferred" geometry (which is not the one I would prefer) is ther better model of reality, and so is "true" in the sense that the universe acutally is best described by a geometry of negative curature. It is a superior model. However, I don't know that it is any more "true" than Euclidean geometry. No formal system can lay claim to being true in an empircal sense.
This isn't right either.
It was imprecise. I was referring to the lack of an empircal basis for the existence of points, lines, etc.
Well, all theories of gravity, as well as those of evolution, are certainly subject to reasonable (non-"perverse") debate.
Based upon what you consider a theory to be, it's perfectly natural for you to feel this way.
I just can't see how it's relevant to talk about what a person might "think" if you strictly limit the information available to him and then cut of his means of obtaining it.
You don't see why the IEP (inertial equivalence principle) relevant to developing the eqautions of SR. Got it. At this point, you could take the word of the various sources which describe it as a postulate. Another option would be to delve further into the issue by seeing just how the formulas themselves are derived. Whether you use the group model (the group axioms insure the transformaiton behave according the IEP) or the classical model (where the IEP is incorprtated directly), it is a fundamental part of the derivation. Of course, you could just keep protesting that you don't see the relevance.
The type of subjectivist characterization of "reality" suggested by the EEP is astonishingly misleading. If true, there simply could be no physics.
You mean, if physics were limited to relativity theory only, and had nothing else to it, it would be almost useless? I agree. I don't see how that stops relativity theory from being one among a number of tools in the box of physicists. No formal construct in physics is an all-in-one tool that can be applied to every situation to get any conceivable answer.
Good things may have come from GR, but NOT because gravitional effects are physically (objectively) indistinguishable from acceleration.
Without the EEP in one form or another, GR does not exist. It is as important to GR as the IEP is to SR.
But who in the hell would suggest that the slope of the lines on the graph paper is what "causes" the other bees to fly straight to the discovered treasure, eh?
Yet, we aould agree there is a correlation between that slope and the flight of the bees, based on their connection to the phenomenon the slope modeled. Are you saying the original phenomenon does not exhibit slope?
I still would not agree. Nor would I agree that a person's refusal to acknowledge any standards would nullify all standards.
OK.
If the accelerated party's measurments have "really" shrunk, then they are defective.
It's a curous defect that comes and goes, then, with no sign friction or unusual transfer of energy. For example, let's say the yardstick is 1 yard long, 1 inch wide, and 0.1 inches thick when you measure it on earth. Then, is goes with an astronaut on a ship accelerated (for the convenience of the math) to 0.6c. By your interpretation, when the yard stick has it's long axis in the direction of travel, it is really .8 yards long, 1 inch wide, and 0.1 inches thick. When the medium axis is in the direction of travel, it is 1 yard long, 0.8 inches wide, and 0.1 inch thick. When the small axis is in the direction of travel, it is 1 yard long, 1 inch wide, and 0.08 inches thick. Do you agree?
Now, when the astronoaut rotates the yardstick to change which axis is in the direction of travel, say from long to short, according to you he is really stretching it by 0.2 yards and flattening it by 0.02 inches. Yet, he won't need to exert any more energy to do that than you would to make the same motion at home. He won't notice any increase in heat from friction as the molecules reposition themselves into a longer, flatter stick. That's part of the IEP. So when you say the yardstick is really defective, what does that mean empirically?
One Brow said: Also the deflection of light by massive bodies was predicted. ... But the actual value for the deflection that he calculated was too small by a factor of two, because the approximation he used doesn't work well for things moving at near the speed of light. When Einstein finished the full theory of general relativity, he would rectify this error and predict the correct amount of light deflection by the sun.
Only after you use the the equations that make space act like it is curved do you get accurate prediciton for the bending of light. Time dilations effects are insufficient.
YOU say it's curved space. I already quoted Al saying it's variable light speed, and the "math expert" saying it's distorted "time" that causes "gravity," not "curved space." Curved spacetime is not curved space.
One Brow said: "The method of analysis for a scientific theory is experimentation, and the assurance that the results are observable and reflect an underlying reality."
We've been through the different meanings that "theory" can take on before. American Heritage conflates theory with experimentation, so I'm not talking about a definition that says observations and/or experimental attempts to disprove a theory ARE the theory. They are not, by my definition, and anyone who uses that definition is simply conflating completely different concepts.
But I quoted your statement primarily for this part: "...and reflect an underlying reality."
Despite lip service paid by some scientists to the (limited) expectations due from a scientific theory, they often equate confirmation of a theory's predictions with confirmation of their HYPOTHETICAL explanations of the underlying cause. Then they want to talk about the "underlying reality" that the theory "proves."
Both geocentricism and heliocentrism can predict the next solar eclipse. Naive supporters of each view will then claim that the accurate prediction of the eclipse PROVES that their explanation is "correct" and represents the "underlying reality." It is, of course, no such thing.
See next post.
This guy makes a point I'm trying to convey. I'm not saying he's right or wrong in his science, but he's certainly right, I think, in his analysis of what is "confirmed" by experiment, and what isn't. He acknowledges the validity of the major "confirmations" of GR, but argues that the (unconfirmed) interpretations of the causes is what has made GR incompatlible with QM.
Some excerpts:
"The most important confirmed predictions of relativity (SR and GR) are that (1) mass increases with motion and is interchangeable with energy; (2) there is an exact equivalence between the gravitational and inertial masses of all matter, (3) clock rate decreases with motion and with a decrease in gravitational potential (altitude); (4) the measured speed of light is the same in every inertial and gravitational frame of reference; (5) light coming from a source with a lower gravitational potential is shifted toward the red; and (6) a star observed near the rim of the sun during an eclipse is displaced away from the sun by 1.75 arcseconds...
Problems with the unification of QM and relativity have arisen because interpretations of the equations of relativity have been made which impute a causal reality that cannot be tested by direct observation. [He then summarizes the standard interpretation of the events, and then notes]: These six interpretations of the relativity theories are interdependent, internally consistent and compatible with the predicted observations....
The observable predictions of the relativity theories have been confirmed beyond any reasonable doubt. It is the untestable explanations of these predictions that have been challenged here. An alternate reality to six of these explanations is .presented that is not only compatible with quantum mechanics but uses the quantum field to explain gravity and unify it with inertia."
http://physicsessays.org/resource/1/phesem/v23/i1/p48_s1?isAuthorized=no
The point is this: Confirming a prediction of a theory cannot confirm that the theory represents "underlying reality."
I suspect you will freely acknowledge this point, and then continue into the indefitinite future with statements involving "underlying reality," which contradict your acknowlegement.
Prefatory note: The "next post" I referred to was made, but does not appear.
One Brow said: "Which of the two postulates of SR mentioned above (constant speed of light, inertial equivalence) do you think was not generated/confirmed inductively before the creaton of SR?
I can quote Al directly on this if you still think his axiom was "empirically" or "inductively" arrived at.
The "constant" speed of light, obviously. That was merely postulated by Al and is the fundamental axiom of his theory. As such, it cannot be confirmed or disconfirmed, merely accepted or rejected. It has never been confirmed, just assumed. By "constant," I do not mean "measured" to be constant, I mean Al's hypothesis that it is, in physical fact, constant, and all that is implied by that.
This assumption is NOT made by LR, and LR explains and predicts all experimental outcomes just as well as SR. Of course LR's refusal to adopt this axiom cannot be directly confirmed or disconfirmed either.
One Brow said: "You don't see why the IEP (inertial equivalence principle) relevant to developing the eqautions of SR."
No, you miss the point completely. I did not say it is irrelevant to "developing equations." It IS an equation, and it "develops" itself in that sense. I'm making the distinction between theoretical/mathematical formalism and physical reality. No one says gravitation is "physically" equivalent to acceleration.
To clarify: I have not really paid a lot of attention to your useage of the new phrase "IEP." I was addressing the EEP, not what you are calling the IEP.
I have addressed what I take you to mean by the term "IEP" at some lenghs in prior posts. Let me just ask: I don't think so, but by "IEP." do you mean the proposition that it is "impossible" to distinguish which of two relatively moving objects is in motion? If so, as I have said, that is NOT a "principle" of either Galliean or Einstienian "special" relativity. Do you disagree?
We can all agree that the motion of a ball being thrown "straight up" and down on a ship moving at sea will have a different appearance to an observer standing on the shore. But to go further and say "Therefore, no one can ever know which one is moving (has been previously accelerated) relative to the other" is not implied, is not a physical principle, and is not even accurate.
One Brow said: "Yet, we aould agree there is a correlation between that slope and the flight of the bees, based on their connection to the phenomenon the slope modeled. Are you saying the original phenomenon does not exhibit slope?"
Yes, I'm saying that "slope" on a piece of graph paper is something completely independent of, and distinct from, a bee's dance, it's significance and the resulting behavior of his homey's. Lines on paper have NOTHING to do with the phenomenon, as an objective occurence in nature. They would occur just the same if no one ever invented graph paper and the formal constructs involved in employing graph paper. Lines on paper can in no way "cause" the phenonemon or the phenomena which follow.
One Brow said: "So when you say the yardstick is really defective, what does that mean empirically?"
Good question. There are those of both the SR and LR persuasion who deny that there is any "real" length contraction effect, and, as far as I know, such an effect has never been unequivocally confirmed experimentally.
That said, an imputed "length contraction," at least in appearance, is an integral aspect of SR, and I was simply assuming it's validity when discussing what SR says "really happens."
John Stuart Bell has a good (I think) answer to your question, but I can't find it right now (haven't really looked). But, as I recall, it involves the notion that everything in one's perceptions (not JUST the yardstick) changes simultaneously when a yardstick is rotated which makes it sound like an illusory change, but I'm not sure about that.
But the more essential point is the equivocation involved in the "standard" interpretation of SR. This equivocation has been discussed in it's mathematical details in posts I have already made.
Basically it kinda boils down to this. One guy's miles may be another guy's half-miles. Fair enough, and easy enough to understand. The equivocation comes in when one tries to treat them as identical lengths because (supposedly), after all, a MILE is a MILE.
You can't legitimately treat a half-mile and a mile as being the SAME length. They aren't. Comparing "apples to oranges" is no comparison at all if you claim they are identical fruits.
Put another way, the "myth" that SR is a theory which adopts a "strictly relational" view of relative motion and that the principles of SR require one to adopt such a view is FALSE. It is nonetheless a position which is routinely asserted by textbooks and other advocates of SR. SR is NOT a relational theory of relative motion NOTWITHSTANDING the attempts of Al to originally claim otherwise, which attempts have been perpetuated in crude form by many ever since.
SR is in fact incompatible with a relational view. But that does not stop those who have been "taught" otherwise from insisting that the two are compatible, and from pretending that they understand why this supposed "compatibility" exists, when it doesn't.
One Brow said: "Initial SR assumptions (rough approximations):
2) Identical experiments in different inertial conditions have identical results."
I don't think number 2 is correctly stated, depending on what you mean. The laws of physics, in their simplest form (i.e., without the "fictitious forces" which result from an accelerating frame of reference), will be the same, sure.
But that does not mean the two frames will get the same results. OTHER than light, no other speed is constant. In discussing the moving train and the stationary track-side observer, Al himself points out that if each looks at a flock of flying birds, they will get different answers as to the speed of those birds--this is just the familiar old Galliean relativity.
The implicit question raised by the last post is this:
If the speed of a horse running, a car moving, or the sun moving across the sky is not the same for a person sitting on the ground as one sitting on a moving train, then how can you say the two frames are "equivalent?" And, if they are equivalent, why would they not also be "equivalent" if the speed of light also differed in the two frames? Why would a "constant speed of light" be required to establish "equivalence" to begin with?
I said: "The type of subjectivist characterization of "reality" suggested by the EEP is astonishingly misleading. If true, there simply could be no physics."
You responded: "You mean, if physics were limited to relativity theory only, and had nothing else to it, it would be almost useless?"
Although I have stated it repeatedly, I think you still overlook the point I am getting at.
Let me start with this example, which I have used before. Let's say I cannot subjectively distinguish between (1) an illusionist "appearing" to make a elephant suddenly materialize out of thin air and (2) an elephant really and actually just suddenly materializing out of thin air.
Would that make the two "equivalent," in any OBJECTIVE sense? Subjectively, maybe, but physics is NOT about subjective misperceptions, and least not in the sense of claiming that mistaken appearances reflect "reality."
This approach is strictly subjectivist, and pretends that subjective perceptions dictate reality. It is NOT scientific.
===
One Brow said: "At this point, you could take the word of the various sources which describe it [what you are calling the IEP, whatever that is supposed to mean] as a postulate."
Better yet, maybe you could find such a source and, rather than "take their word for it," independently analyze the true role, if any, it plays in the theory for yourself.
If, by IEP, you are trying to imply the claim that "it is not possible to tell which of two relatively moving objects has previously been accelerated, then I think you would, if you actually analyzed , conclude that it is merely an extraneous and irrelevant attempt to erroneously and inappropriately superimpose a misguided and strictly philosophical claim on a physical theory.
Anyway, Eric, to settle this whole question, once and for all...
I gotcho objective morality richeea, eh?
[pointing to crotch, in case that aint obvious]
This Chink, and his homeys, don't cut Will much slack, and basically call him a fool, eh?
"The concept that coordinates don't matter in the interpretation of Einstein's theory ... necessarily leads to mathematical results which can hardly have a physical interpretation and are therefore a mystification ofthe theory." Moreover, the "covariance principle" is in conflict with Einstein's equivalence principle....for a given frame of reference, there is at most one gauge is physically vaJid among diffeomorphic metrics [6, 7]. Thus, although the Schwarzschild solution 2) is diffeomorphic to the harmonic solution, at most one of them is valid in physics, and thus they are not equivalent in physics....
...as pointed out by Morrison, the "covariance principle" is invalid because it disrupts the necessary physical continuity
from special relativity to general relativity [14, 15]. In fact, Einstein's "principle of covariance" has no theoretical basis in
physics or observational support beyond what is allowed by the principle of general relativity [15]. Nevertheless, Bodenner & Will [16] claimed that their "covariance" results ofthe deflection of light to second order further illustrates the"principle of covariance" and the belief that coordinates in general relativity are completely arbitrary. Such a claim is clear incorrect...
Moreover, an implicit assumption in [Bodenner and Will's] paper is that all the gauges are valid in physics. This misled them to believe that things can be solved with a modification of the definitions. However, physics is not a matter of just definitions alone as in mathematics. 6) It will be shown that there are more such gauges that are invalid in physics....
Will [21] invalidly regards the "covariance principle" as an integral part of general relativity because Will does not understand it. Since physical quantities such as vectors and tensors are measurable and their components are expressed in terms of coordinates. The claim of arbitrariness of physical coordinates, if put Zhou's [5] statement in a clear language, just make no sense in physics....Bodennor and Will [16] also have a problem in distinguishing physics from mathematics. 6) They seem to believe that physics is just a matter definition....Will often does not make enough efforts to see his assumptions have a good ground to be valid."
http://lss.fnal.gov/archive/other1/apri-th-phy-2005-08.pdf
As between two guys, A and B, one of whom has been accelerated to .5c relative to the other, is it "meaningless" to ask whose rulers and clocks "really" changed?
Even if we didn't know the answer, the question would certainly not be "meaningless," but in the case of SR, we have a definite answer, so even better.
But that doesn't stop many people, like yourself, Eric, from making the assertion (as you did in our last relativity thread) that such a question is "meaningless." Why do people say that? Because that what some teacher told them, who himself was told that by his teacher, etc. Funny how even those who have never even considered the implications of logical positivism have no problem asserting its proposition with absolute confidence that they are saying something "meaningful" and correct, ya know?
It is not SR that is hard to understand and which is replete with contradictions/paradoxes. It is the mythical lore about what it is "really" telling you that creates those problems. Much of this lore has been bred from philosophical views that are fundamentally incompatible with SR to begin with.
Al started this, so it's his fault. He was a naive and devout advocate of logical positivism for many years. He later saw the error of his ways and renounced this type of philosophy, but to no avail for many. They just look at his early claims, assume that, since he is a genius, he must be correct, and continue to promulgate his renounced views.
One Brow said: "The method of analysis for a scientific theory is experimentation, and the assurance that the results are observable and reflect an underlying reality."
I agree that physical objects, like rocks and trees, are of a completely different order of things than are elusives concepts like right or wrong, good or bad. It therefore seems like there should be a more objective, concrete reality to any statements about rocks or trees than there is to statements involving moral concepts. To some extent this is certainly true.
But not all statements about rocks and trees take the form of scientific theory. And, to some extent, as we have aleady noted, every scientific theory starts with some postulated assumptions that are not empirical and which cannot, within the context of the theory, be tested. The postulated "constant theory of light" is just such an "untestable" assumption. If you choose to assume it, it is thereafter "self-proving" because you have assumed it from the get-go, and every measurement you make and every logical conclusion you draw will presuppose it. If you refuse to assume it, the logical consequences of that assumption are also "self-proving."
Can it be "falsified?" Well, yes, and no. If the predictions of your theory of gravity don't work out as planned, you can refuse to concede that your theory is falsified, and simply posit unseen, and theoretically unseeable, explanations to save it, such as "dark matter." If things appear to exceed the speed of light, you can always say, however nonsensical, that the objects which are apparently receding from each other at speeds faster than ligt are in fact motionless, and that space is merely expanding, thereby "saving" your theory.
So, actually, no it can't really be falsified any more than it can be proven, although there does come a point where the "epicycles" just become a little too much to stomach, from an aesthetic perspective.
When an otherwise useful theory encounters observable phenomena which the theory says will NOT happen, and even when no satifactory ad hoc creation appears plausible to save it, it is seldom seen as a "falsification" of the theory. Instead it is merely seen as an unexplained "anomaly," not a "falsificaton."
For many, it is actually seen as a confirmation of the theory, and they will rejoice that "the exception proves the rule."
Historical contingencies often play an important role in which theories get accepted. For example:
"The failure of Maxwell's equations to exhibit invariance under the Galilean transformation was corrected by Hertz through a simple, but today largely forgotten, mathematical trick. This involves substituting total (convective) time derivatives for partial time derivatives wherever the latter appear in Maxwell's equations. By this means Hertz derived a formally Galiean-invariant covering theory of Maxwell's vacuum electrodynamics...Had Hertz's mathematical accomplishment received wider recognition, his invariant covering theory of Max-well's could have furnished the formal key (almost two decades before Minkowski's "covariance") to unification of the "relativistic" properties of electrodynamics and Newtonian mechanics, explanation of the Michelson-Morley result, etc..
Although Hertz's invariant equations went down the drain, they depend only on certain immutable mathematical facts and thus are subject to continual rediscovery. (The modem independent rediscoverers include S. Kosowski, F.D. Tombe, C.I. Mocanu, and the present writer - all originally ignorant of Hertz's priority.)...
There has existed in the published literature for one hundred years an invariant covering theory of Maxwell's electromagnetism due to Hertz. It should be emphasized that a covering theory really "covers." That is, the empirically validated electromagnetic "physics of one laboratory," wherein field detectors are at rest, is identical in Maxwell's and in Hertz's theories....we are entitled to speak of the Hertz equations as manifestly invariant at first order. This means that they obey a Galilean relativity principle: the laws of electromagnetism, like those of Newtonian mechanics, are invariant under transformations among different inertial systems...
His theory did not become physics, because physics is never equations alone but equations plus physi-cal interpretation. As often as not, and certainly in this case, interpretation proves the stumbling block. On the side of interpretation Hertz made a fa-tally bad guess...."
http://www.angelfire.com/sc3/elmag/files/phipps/phipps01.pdf
Maybe the problem Al was trying so hard to "solve" had already been solved by Hertz, eh?
Many who argue that SR is "superior" to LR, argue that Lorentz arrived at his equations on an "ad hoc" basis. Lorentz, and many others, deny {ied} this. The real underlying criticism is probably that Lorentz's attempt to provide a rational physical interpretation were less than 100% satisfactory.
Even assuming that's true, one simply takes the weakest point of SR and tries to make it a strength using that line of argument. Al merely POSTULATED his conclusions, and made no attempt whatsover to provide a physical interpretation of his postulates. Like Newton, with his mathematical formula for gravitation, Al "fingered no hypotheses." Al himself conceded that such a "theory" was vastly inferior to a theory which also provided a plausible and testable physical interpretation.
You want to attack any attempt to phsyically explain the Lorentzian transformations, yet seem to think Al did a wonderful job by refusing to provide any explanation whatsover for the theory he was propounding. Go figure, eh?
Note, a long-ass post I just made about Hertzian electrodynamics just disappeared, eh? It was number 464, until it was replaced as such by the "ad hoc" post I just made.
Eric, last I looked, there were supposedly 465 comments here. I see that you have reimported some from the spam bin, and that might raise it to 467 or so. But I'm reading a count of 471. I am assuming that, as before, you have added some comments which I can't see.
Somehow, that got rectified last time, but I don't know how. It is something you did?
You have indicated that you cannot see why I give any credence to LR over SR. It should be obvious, but let me elaborate, once again.
I object to the mystical, subjectivist, mode of thought that SR advocates almost invariably display. Their arguments are fallacious and are not about physics, but rather about a philosophy that is incompatible with an objective view of physics. For better or worse, the discipline of physics presupposes an "objective" reality which reality does not depend on the perceptions of the subjects who observe it.
SR can convincingly demonstrate how and why two relatively moving observers will have different perceptions of time and distance (space). Fine, I appreciate that. It cannot, however, demonstrate that both perceptions are "equally valid," and such a suggestion is inherently anti-physical.
To me, anyone who can't see that would have just as much trouble seeing that there is any question about whether Jesus walked on water or multplied fish out of thin air. If they uncritically accept such propositions at the outset, there is really nothing you can say from a "logical" standpoint to dissuade them. They don't even think in such terms.
Eric, last I looked, there were supposedly 465 comments here. I see that you have reimported some from the spam bin, and that might raise it to 467 or so. But I'm reading a count of 471. I am assuming that, as before, you have added some comments which I can't see.
Somehow, that got rectified last time, but I don't know how. It is something you did?
No, nothing I did, except continue to post comment. The comment counter that appears on the screen and the comment counter that actually puts comments into pages seem to be in disagreement. When the screen counter exceeds 600, I beleive you will again see a blank final page of comments until the pagination counter also exceeds 600. Based on my observation, I am sure the screen counter is in error, I don't know about the pagination counter.
YOU say it's curved space. I already quoted Al saying it's variable light speed, and the "math expert" saying it's distorted "time" that causes "gravity," not "curved space." Curved spacetime is not curved space.
Again, time distortions in and of themselves proved insufficient by half to explain the bending of light. Also, it's curious that you think time could be curved without space also being curved as a result; to the degree they exist, they are too well inter-connected for that to be true.
They are not, by my definition, and anyone who uses that definition is simply conflating completely different concepts.
I understand that you like to form a broader separation between them than I would form, or the dictionary and the various scientists whose blogs I read would form. You seem to see theoritical aspects and emprical aspects of science as being largely disjoint, connected primarily by subject matter, with the theory free to take on a life of its own. I see them as interwoven, the theory being subordinate to the empircal data, shaped by the data as much as by the human imagination.
Despite lip service paid by some scientists to the (limited) expectations due from a scientific theory, they often equate confirmation of a theory's predictions with confirmation of their HYPOTHETICAL explanations of the underlying cause. Then they want to talk about the "underlying reality" that the theory "proves."
I agree. Careless thinkers often confuse the notion that science can prove anything. More careful thinkers are clear that science provides evidence that can be a counter-example to various ideas, but never an afirmation of an idea except in our inability, at the time, to form said counter-example. That gets combined with the human need to keep things simple in our description (among other preferences, of course) to create minimal theories, but again, careful scientists understand these are simplifications, not proofs.
I suspect you will freely acknowledge this point, and then continue into the indefitinite future with statements involving "underlying reality," which contradict your acknowlegement.
I suspect you will continue to take statements of behavior as statements of immutable fact, and try to correct me on my misunderstandings and apparent inconsistencies.
One Brow said: "Which of the two postulates of SR mentioned above (constant speed of light, inertial equivalence) do you think was not generated/confirmed inductively before the creaton of SR?
I can quote Al directly on this if you still think his axiom was "empirically" or "inductively" arrived at.
The "constant" speed of light, obviously. That was merely postulated by Al and is the fundamental axiom of his theory. As such, it cannot be confirmed or disconfirmed, merely accepted or rejected. It has never been confirmed, just assumed. By "constant," I do not mean "measured" to be constant, I mean Al's hypothesis that it is, in physical fact, constant, and all that is implied by that.
I asked you what postulate was not generated/confirmed on an empirical basis, and you say the constancy of the speed of light, but then acknowledge that the speed was acutally measured to be constant regardless of the motion of the observer? I'm not sure if we have a disconnect here on "empirical" (the outcomes of teh experiements) or on "inductive" (the use of emprical data to suggest broader conclusions).
This assumption is NOT made by LR, and LR explains and predicts all experimental outcomes just as well as SR. Of course LR's refusal to adopt this axiom cannot be directly confirmed or disconfirmed either.
LR actually does use, recognize, and rely upon the constancy of the two-way speed of light. If it did not, it would no more be a theory than Newton had a theory of gravity, it would just be a collection of equations with no underlhying explanation. If light could travel at c - a in one direction and c + a in the other direction, and you would still wind up with an overall speed of c, that would be an interesting and reasonable suggestion. However, if light traveled at c - a in one direction, it would need to travel at c + ca/(c - 2a) in the other direction to maintain an average of c. I fully acknowledge that I reject that possibility based on the rather arbitrary-looking nature of the relationship, even though it could be true. It makes more sense that if c is a two-way constant (as acknowledge and used by LR and SR), it is a one-way constant.
No one says gravitation is "physically" equivalent to acceleration.
The EEP also makes no such claim.
I have addressed what I take you to mean by the term "IEP" at some lenghs in prior posts. Let me just ask: I don't think so, but by "IEP." do you mean the proposition that it is "impossible" to distinguish which of two relatively moving objects is in motion? If so, as I have said, that is NOT a "principle" of either Galliean or Einstienian "special" relativity. Do you disagree?
The IEP is a pairs of claims that the speed of light is a constant, and that when looking at the results of experiements conducted entirely within an interial frame you can't tell if that frame is moving or not compared to some rest frame. The "enitrely within" would mean it is possible to make this determinaition if your experiments go outside your frame (such as opening a wimdow).
Yes, I'm saying that "slope" on a piece of graph paper is something completely independent of, and distinct from, a bee's dance, it's significance and the resulting behavior of his homey's.
I disagree. While the observer can certainly choose different means of recording actions before the recording begins, if the recording is properly done all of those decisions are made beforehand. At that point, it is the bee's dance that controls the slope within the framework of those decisions (and the limits of measurement error, etc.). If you simply mean there is no feedback from the graph to the bee, as you indicated below, I agree. Still, the connection from the bee to the graph is clear. The connection from the bee to the behavior of the other bees is obvious. Thus, the graph and the behavior of the other bees are indirectly linked. If the link is strong enough, the graph can be used to preduct the behavior of the other bees, even though it does not control them.
Good question. There are those of both the SR and LR persuasion who deny that there is any "real" length contraction effect, and, as far as I know, such an effect has never been unequivocally confirmed experimentally.
Not directly, but these two sites confirm the existence of a predicted result of length contraction: magnetic fouces in a copper wire.
Basically it kinda boils down to this. One guy's miles may be another guy's half-miles. Fair enough, and easy enough to understand. The equivocation comes in when one tries to treat them as identical lengths because (supposedly), after all, a MILE is a MILE.
You can't legitimately treat a half-mile and a mile as being the SAME length. They aren't. Comparing "apples to oranges" is no comparison at all if you claim they are identical fruits.
I agree. YOu need to be careful to distinguish between the various ways the "half-mile" is, and is not, an actual mile.
I'm not interested in defending a relational view of the universe.
Al himself points out that if each looks at a flock of flying birds, they will get different answers as to the speed of those birds--this is just the familiar old Galliean relativity.
My apologies for not being clear. It is limited to experiements within the inertial frame only. If both observers are looking at a flock of birds, each is going outside his inertial frame.
If the speed of a horse running, a car moving, or the sun moving across the sky is not the same for a person sitting on the ground as one sitting on a moving train, then how can you say the two frames are "equivalent?"
The equivalence is for experiments within the inertial frame only. That is all the equivlence SR postulates and all it requires to produce its equations.
And, if they are equivalent, why would they not also be "equivalent" if the speed of light also differed in the two frames?
They would be. The constancy of light is a separate, independent postulate (as you have pointed out with LR).
Although I have stated it repeatedly, I think you still overlook the point I am getting at.
Your point seems to be that, because the postulates of relativity refer to limitations that seem arbitrary to you, and not reflective of a broader philosophical reality, they aren't saying anything real. I agree that the postulates refer to limitations that can seem arbitrary and do not reflect the totality of a broader physical reality. However, for me, it is more important they accurately reflect the aspects of reality that they are trying to incorporate. That you can gather data not relevant to the theories, and use it say things the theories don't say, does not invalidate SR/GR. It is important to keep in mind what these limitations are, though. I have been agreeing with that all along.
If, by IEP, you are trying to imply the claim that "it is not possible to tell which of two relatively moving objects has previously been accelerated,
If both frames are currently inertial, then using experiments conducted within each frame of reference only, it is not possible to compare the results and determine which frame is accelerated. This does not rule out other means of making that determination, and those other means are not relevant to SR.
This Chink, and his homeys, don't cut Will much slack, and basically call him a fool, eh?
Einstein proposed the "covariance principle" because he was unable to give a meaning to coordinates ofa physical space. Unexpected by Einstein, his equivalence principle was practically substituted by Pauli's version [8] in spite of strong objections from Einstein. The popularity ofthis substitution was assisted by the incorrect belief that Einstein's equivalence principle is not needed or only approximately valid. The former is, in part, due to that the general case of obtaining space contractions and the time dilation has not been adequately studied. Thus, the crucial role of Einstein's equivalence principle was not understood. Due to conceptual errors, efforts to obtain a metric for uniform gravity had failed.
Basically upholding the EEP. What was your point here?
As between two guys, A and B, one of whom has been accelerated to .5c relative to the other, is it "meaningless" to ask whose rulers and clocks "really" changed?
Unless you know which one was accelerated, pretty much, at least in that it's a question you can't answer.
And, to some extent, as we have aleady noted, every scientific theory starts with some postulated assumptions that are not empirical and which cannot, within the context of the theory, be tested. The postulated "constant theory of light" is just such an "untestable" assumption.
I agree with you about the existence of untestable assumptions, such as the isotropy of space. I disagree about the particular of the constancy of the speed of light not being testable. At a very basic level, you set up a two light sources (one on a moving platform), a mirror, and a clock, and measure the time it takes when the light source is moving or stationary. The speed of light has been measured in many different times, manners, and places. The leap from those measurements to a general rule is inductive thinking, not pulling a notion from thin air. I do not understand why you insist on saying it is not empirical, unless you mean that all such inductive leaps become non-empirical by the nature of their being universal.
Can it be "falsified?" Well, yes, and no. If the predictions of your theory of gravity don't work out as planned, you can refuse to concede that your theory is falsified, and simply posit unseen, and theoretically unseeable, explanations to save it, such as "dark matter."
I agree dark matter is more a place-holder, or a sign that theory needs improvement, than a likely reality.
If things appear to exceed the speed of light, you can always say, however nonsensical, that the objects which are apparently receding from each other at speeds faster than ligt are in fact motionless, and that space is merely expanding, thereby "saving" your theory.
That reads like you are conflating three different points of view (our view, the view in the other galaxy, and the view of the CMB) as being the same thing. It's basic SR that a third, inertial observer could see each of two acceleragted objects as separating by more than c (say, 0.6c in soppsite directions), but the accelerated objects don't see each other that way. We still see light from those objects, for example, just with a very strong redshift. If they were moving faster than c from our perspective, how could we see their light?
Many who argue that SR is "superior" to LR, argue that Lorentz arrived at his equations on an "ad hoc" basis.
I don't see the relevance of that claim, regardless. Whether Lorentz specifically did or not is nor relevant, as long as the theory itself can be so used.
Note, a long-ass post I just made about Hertzian electrodynamics just disappeared, eh? It was number 464, until it was replaced as such by the "ad hoc" post I just made.
It was a nice read. Were you attempting to draw a parallel between Maxwell/Hertz and SR/LET?
I object to the mystical, subjectivist, mode of thought that SR advocates almost invariably display.
I agree that many people who don't understand relativity give a mystical interpretation to it,and I approve of your objection to that.
If I remember my high school geometry correctly, the "formula" for the area of a circle is typically stated as "2*pi*R." I have always thought this way of stating the formula was misplaced, in a sense. I always thought of it as pi * D.
The two are completely equivalent, mathematically, so it really makes no difference, result-wise, which formulation you use. But why would you first cut something (the diameter of a circle) in half (the radius) and then multiply your result by 2, just to get back to where you started (the diameter)? Seems rather circuitious, ya know?
But that's not even why I prefer the formulation of pi * D. I think my formulation is more likely to expose, rather than disguise, the nature of the relationship of the area of a circle, as opposed to a square.
In such terms, where one side of a given square is the same as the diameter of a particular circle, the "area" of a square would be D-squared. For the corresponding circle that would fit completely within such a square, just touching the sides of the square at select points, it is obvious that the area of the circle would HAVE to be less than D-squared, because a circle will never include all the area contained by a square with a side length equal to it's diameter.
The degree by which it is less is strictly proportional. If you round pi to 3, then the proportion is 3/4. When I looked at it this way, "pi" didn't seem quite so mysterious to me. Pi has the appearance of taking on much more mysterious, even "magical," powers when the formula is expressed as 2 pi R from my perspective.
The point? Well, I don't know, exactly. I have seen many (often mathematicians) seem to pontificate in awe about the qualities of pi and, like a pythagorean, seem to impute some cosmic mystical significance to the number. Sometimes the very way you choose to frame a question can influence the answer you give to it, and the impressions of what meaning your answer has, once given, I guess. Not objectively, but subjectively.
One Brow said: "I'm not sure if we have a disconnect here on "empirical" (the outcomes of teh experiements) or on "inductive" (the use of emprical data to suggest broader conclusions)."
We definitely have a "disconnect" on what is empirical and what is hypothetical. I guess we'll never agree, unless and until you reflect more on the difference, at least.
I'll try to give one more example, although I really don't expect much to come of it. Heraclitus, a brilliant pre-socratic greek philosopher, was also known at "the Dark One" for his seemingly obscure pronouncments. Heraclitus was the first "relativist," but that is really neither here nor there for the point I am trying to make. You probably know the guy. He said "You can't step in the same river twice," among other things. He also said that the only thing which permanent is impermanence itself (or words to that effect).
Now for my example. Heraclitus said "The sun is the size of a man's foot." What is that supposed to mean? Well, I take it this way: If I'm laying out on the beach, just catchin a few rays, and all, and some Babe comes by and says sumthin to me, I'm gunna want to see just what she looks like, head to toe. But when I look up at her while the sun is behind her, I won't be able to see her. In that case, I can, if I'm agile enough, simply lift my left foot and position it in such a way as to block out the entire sun. So the sun is the size of (actually smaller than) my foot in that sense.
This is EMPIRICAL. But it would not be an "empirical" conclusion for me to say that, therefore, the sun REALLY is exactly the size of my foot. That statement, as made by Heraclitus, is merely an observation about the relative effects of perspective. If I transmute his claim into one of purported immutable fact, then I have gone far past mere empirical observation and have incorporated a number of physical assumptions (however tacit) as premises for my conclusion. That process is theoretical and mental, not "empirical." This is basically what Al did with his "constancy of light" conclusion.
One Brow asked: "If they were moving faster than c from our perspective, how could we see their light?"
If I understand your question, then you once again simply demonstrate the human tendency to assume that one's tacit assumptions are indisputably true. Eiher that, or just the standard equivocation is at play.
Let's say they are moving away from us at a speed exceeding roughly 700 million miles an hour. Is that "faster than the speed of light?" Not if light can, move, just for example, at the rate of 10 billion miles per second. Whether they are truly moving faster than the speed of light depends on what you suppose the speed of light to be.
One Brow said: "Basically upholding the EEP. What was your point here?"
Point? The point is that the chink was dissin Will, mainly, and I approve of that wholeheartedly.
Seriously, though, I saw the part you quoted, and that too was interesting. That I did not quote that portion should tell you that it did not make the "point" that I was focusing on. Actually, there are two or three points being made which are relevant to issues we have recently touched on in this thread, i.e.,
1. The significance, especially the physical significance, of the alleged "co-variance" of GR. I took "co-variance" to somehow be crucial (for you) to what you were calling the "IEP."
2. The failure to distinguish physics from math and the alleged tendency of some physicists to believe that physical problems can be meaningfully "solved" by definition.
3. The "mystification" of a theory that can result from an over-reliance on mathematical symbolism without regard for physical meaning. This is just the type of thing that I took your quote of Von Neumann to be addressing.
While on the topic of the "basic axioms" of relativity, let me address this one more time:
One Brow said: "The IEP is a pairs of claims that the speed of light is a constant, and that when looking at the results of experiements conducted entirely within an interial frame you can't tell if that frame is moving or not compared to some rest frame."
You have skipped a step. "What you can tell" about movement is NOT the proposition which the "relativity principle" addresses, although it may be a logical deduction from the RP. The RP merely says the laws of physics will be the same. Again, the essential underlying point is that all objects (desks, chairs, pencils) etc. within a given moving system will share the same intertial motion (tendency to continue in a straight line UNLESS acted upon by an external force). The essential point IS not about what you can discern, although that is not entirely irrelevant either.
Again, Gallileo made the point to counter the long-standing traditional argument that the earth could not possibly be moving because, if it was, we could not throw a ball straight up and have it come straight down. The traditional argument failed to appreciate what later became Newton's law of inertia.
But the fact that we supposedly can't "tell" that we are revolving around the sun does NOT prove that we are not. Nor does it by any means show that we can "never know." Nor does it even prove that we cannot, from the framework of earth itelf, detect if the earth is moving.
We can and do know, by virtue of such things as stellar abberation, foucault's pendulum, the appearance of coriolis forces, the sagnac effect, etc. It doesn't hurt of have pictures from outer space which evidence this motion, but they are not necessary.
Nonetheless SR advocates often seem to think that the relativity principle "proves" that there is no "absolute motion," that there is no possible way to detect that the earth is moving, etc. They argue such conclusions with a straight face, not even aware of how fallacious their claims are. All supposedly based on what you are calling the "IEP," which, again, is NOT the RP (relativity principle).
Just made another post (about the chink and your "IEP") which was swallowed by the spam filter. Will leave off for now.
One Brow said: "It was a nice read. Were you attempting to draw a parallel between Maxwell/Hertz and SR/LET?"
Well, the primary point was, as stated, that historical contingencies can make a big difference as to which competing theories end up being accepted as "standard," but, yeah, this bears on several points we have been discussing.
The "empirical" (or not) basis of Al's theory, for example. Historians seem to agree that one "premise" in the reasoning that led Al to his conclusion was that "maxwell's equations" were impeccable and accurate beyond dispute. He was therefore trying to account for the fact that they don't exhibit Galliean invariance. If that "premise" was mistaken, and he knew it, he presumably would never have ended up were he did.
According to Phipps, Hertz had already completely "covered" maxwell's equations while making mathematical adjustments that rendered them galliean invariant. So, in that sense, Al was operating on mistaken assumptions and was trying to "solve" a non-existent problem. He could have dispensed with his SR theory just as readily as he dispensed with an ether theory. Neither were needed.
If several factors (assumptions, measurements, whatever) have to be combined to give you an ultimate result, then you have the option of making adjustments at different places. If I want to reach a certain number as the "speed" of something, for example, I can adjust either the time, the distance, or both to some degree, to get my desired result. Likewise, you can change your calculations for all of physics if you want them to be compatible with maxwell's equations or you can, as Hertz did, simply changes your calculations of maxwell's equations to make them compatible with "all of physics." Same result, either way. No immediate way to prove that either way is "right," let alone that one way is obviously correct while the other is obviously incorrect.
I'm now elaborating on a post that was dumped, but I presume you will restore it in good time.
Here's one thing I find ironic: Eistien's "principle of relativity" was, in form, exactly the same as the prevailing galliean principle. Basically it said that the laws of physics were the same in all inertial frames of reference.
But, as I have noted, Galliean used some of the logical implications of the principle to explain how, despite the lack of "apparent" motion, the earth REALLY was rotating and revolving around the sun. It was, in a sense, intended to explain why deceptive appearances should be mistaken for, or substituted for, "reality."
Naive (and illogical) "logical positivists" (relationalists) have completely inverted the essential lesson to be learned from the principle of relativity. In essence, they claim that deceptive appearances SHOULD BE identified with, and substituted for, "reality." And they think that Al's theory dicates such a view when it does no such thing.
Go figure, eh?
Edit: "It was, in a sense, intended to explain why deceptive appearances should [NOT] be mistaken for, or substituted for, "reality."
Heh, I got a kick out of this statement by Phipps:
"Maxwell's luminiferous ether faded like the Cheshire cat's smile and was replaced physically by ... nothing (the most infrangible substance known - with the possible exception of mathematical vectors, the material of which the present writer was taught that electric and magnetic fields are fabricated)."
The theory that is most immune to refutation is, the one that relies on NOTHING to explain it. The "possible exception" being one which relies exclusively on "mathematical vectors."
You probably don't think it's a humorous as I do, but, then again, it aint my turf that's being attacked here. I aint no mathematician.
Phipps does not seem to appreciate having been taught that electircal and mathematical fields are fabricated from "mathematical vectors." As I read him, he is making the same objection (with which you disagree) that I am making about any claim that sloping lines have ANYTHING (physical) to do with dancing bees.
I read the wiki page on the "relativity of simultaneity" which you cited, btw. What a bunch of self-referential mumbo jumbo. That author actually seems to think he is "explaining" something in a physical sense.
The "relativity of simultaneity," as I see it, is nothing special or distinct in itself. It merely follows from any supposed relativity of time and/or distance. Yet these authors often act like one explains the other somehow. It's like saying the conclusion proves the premise, and the premise proves the conclusion. Entirely circular and empty.
That whole page again strikes me as written by one who cannot distiguish abstract concepts from concrete entities, one who cannot distinguish formal mathematical symbolism from physical interpretation, and one who, as Al put it, has seen a thousand trees, but never a forest.
I will note, however, that at least it makes some valid points that I have repeatedly tried to convey in these discussions, for example:
It does correctly identify the principle of relativity and it doesn't conflate this with some supposed principle of "IEP" which says "all motion is relative" when it notes that "Special relativity does not postulate that all motion is 'relative'; the postulates are that the laws of physics are the same in all inertial frames and..."
It cautions one from believing that SR and GR are based on the same concepts when it says: "It is important for advanced students to be aware that special relativity and General Relativity differ about the nature of spacetime. General Relativity, in the form championed by Einstein, avoids the idea of extended space and time and is what is known as a "relationalist" theory of physics. Special relativity, on the other hand, is a theory where extended spacetime is pre-eminent."
But, as many of the sources I have already cited demonstrate, GR does not really function as a "relationalist theory of physics," as claimed here. Granted, Al wanted it to be that, but....
I was confusing the formula for the circumference of a circle with the one for area in my previous post, which just shows you how detached I am from all those formulaes. The point is the same, but the details are off.
The "circumference" (perimeter) of a square is 4D is the sense I was using it, while the circumference of a circle is approximately 3/4 of that. That's what I was trying to say.
With respect to a quote from a wiki article, I said: "But, as many of the sources I have already cited demonstrate, GR does not really function as a "relationalist theory of physics," as claimed here. Granted, Al wanted it to be that, but...."
In fairness to the wiki author, he appears to be acknowledging the distinction between an actual relationalist theory and a wannabe relationalist theory. He does say, after all: "General Relativity, in the form championed by Einstein, is what is known as a "relationalist" theory of physics."
How many "forms" of GR are there, I wonder? One of those "forms" appears to be a form which Einstein "championed." I don't think this is simply referring to a field versus a geometrical interpretation, but it's not 100% clear. I actually take the author to be hinting at the fact that Al originally thought he had fulfilled Mach's principle and argued that accleration had been rendered "relative" rather than absolute. Whatever is intended, the author does seem to distinguish between the meaning which Einstein gave to GR and other, presumably more consistent, "forms" of GR.
I always thought of it as pi * D.
There are mathematicians who actively try to replaice pi with tau (tau = 2 * pi). You could join in their chorus.
The point? Well, I don't know, exactly. I have seen many (often mathematicians) seem to pontificate in awe about the qualities of pi and, like a pythagorean, seem to impute some cosmic mystical significance to the number. Sometimes the very way you choose to frame a question can influence the answer you give to it, and the impressions of what meaning your answer has, once given, I guess. Not objectively, but subjectively.
I agree with you here. I realize you don't think I do, or that I'm being inconsistent. But I do, and I'm not. for me, math is simply a good way to model the behaviors we see around us, a very useful method of simplfying and categorizing the world. It makes no more sense to me to pontificate on the wonders of pi or e than it does to marvel at the beauty of an alphabetacal storage system. Of course, I do occasionally see the art in a particular proof (and have even come up with a variation on one I haven't seen before that is particularly nice, in my opinion), but I don't attribute any greater mystical significance to that than I would to the Mona Lisa (although some people seem to find mysticism there, as well).
That statement, as made by Heraclitus, is merely an observation about the relative effects of perspective. If I transmute his claim into one of purported immutable fact, then I have gone far past mere empirical observation and have incorporated a number of physical assumptions (however tacit) as premises for my conclusion. That process is theoretical and mental, not "empirical." This is basically what Al did with his "constancy of light" conclusion.
It is quite possible the constancy of light is a local phenomenon, or only appears two-way, or any other number of things. However, what you're really questioning here is not the constancy of light, but the isotropy and homogeneity of space. I absolutely, fully grant you that these are untestable assumptions that scientists use, simply because without them I'm not sure the process we know as science is even possible. In that regard, maybe light, gravity, and electric charges behave differently near Alpha Centauri, or in the Andromeda galaxy, or on the other side of the universe. Perhaps there are even different frequencies of light, yet untested, that propogate at different speeds than the light frequencies tested so far in our local environment.
Ultimately, photons seem to have no consciousness, and don't decide how fast they go. They go at the speed of light, whatever it is, because they are light. The notion that if you fire two photons in identical conditions, they will achieve the same speed, isn't mystical, it's an assumption that behavior is regular.
The measuring of the speed of light is not a matter of perspective. We can measure it directly by bouncing it off things, or indirectly by using wavelenghts and interference patterns. Either way, the results appear the same to all observers. I agree that your example is a good reason why observations in science should be repearted often, by different people, in different venues, using different means. This has been done for measuring the speed of light.
If I understand your question, then you once again simply demonstrate the human tendency to assume that one's tacit assumptions are indisputably true. Eiher that, or just the standard equivocation is at play.
Let's say they are moving away from us at a speed exceeding roughly 700 million miles an hour. Is that "faster than the speed of light?" Not if light can, move, just for example, at the rate of 10 billion miles per second. Whether they are truly moving faster than the speed of light depends on what you suppose the speed of light to be.
You are correct, I am taking for granted that my assumptions of homogeneity and isotropy are true. However, even if they are not, c would still be whatever the speed of light is locally. If you want to claim that on the other side of the universe c is 10 billion miles per second, there is no method by which that cvan be disputed, and you are free to believe it. It still means the galaxy is slower than c. If teh galaxy was faster than c, then the light would be moving away from us when it was released, and we wouldn't see it.
You have skipped a step. "What you can tell" about movement is NOT the proposition which the "relativity principle" addresses, although it may be a logical deduction from the RP. The RP merely says the laws of physics will be the same.
I find "the laws of physics will be the same" to be a little broad, since that would apply even if physics was not relativistic. Perhaps a little more precision, yet still making your point, that the results of local (confined to the inertial frame) experiements will be the same.
We can and do know, by virtue of such things as stellar abberation, foucault's pendulum, the appearance of coriolis forces, the sagnac effect, etc. It doesn't hurt of have pictures from outer space which evidence this motion, but they are not necessary.
I believe that, except for stellar aberration, those are proofs of rotation, not revolution. Otherwise, you are of course correct. We have many tools besides relativity that say we are orbiting the sun, rather than the converse.
Nonetheless SR advocates often seem to think that the relativity principle "proves" that there is no "absolute motion," that there is no possible way to detect that the earth is moving, etc.
After everything I've said on the subject, I expect you are not referring to me.
All supposedly based on what you are calling the "IEP," which, again, is NOT the RP (relativity principle).
It's the RP combined with the constancy of light, even if you preferred a different wording.
Well, the primary point was, as stated, that historical contingencies can make a big difference as to which competing theories end up being accepted as "standard," but, yeah, this bears on several points we have been discussing.
I think you, and probably Phipps, are also underestimating the appeal of the space-time symmetry in Maxwell's equations, that Phipps acknlwedges he must surrender for Hertz's variation.
The "empirical" (or not) basis of Al's theory, for example. Historians seem to agree that one "premise" in the reasoning that led Al to his conclusion was that "maxwell's equations" were impeccable and accurate beyond dispute. He was therefore trying to account for the fact that they don't exhibit Galliean invariance. If that "premise" was mistaken, and he knew it, he presumably would never have ended up were he did.
That's the basis for one person, perhaps. However, relativity was inevitable, regardless of whether you use Maxwell or Hertz. It is the inevitable consequence of Galiean relativity and the constancy of light, both of which were experimentally confirmed. If not Einstein motivated by Maxwell, the same equations would have come about 10 or 20 years later, the same paradoxes, the tendencies to create mystical features around simple descriptions, and you would be proposing that if Feynman had not been searching for a space-time symmetrical notion of light, because Maxwell's theory had fallen by the wayside, he never would have come upon relativity. Relativity is not a fad, a nice thought, or a work of art. It's a model of how the universe actually works, and its creation was inevitable.
Same result, either way. No immediate way to prove that either way is "right," let alone that one way is obviously correct while the other is obviously incorrect.
Why would anyone try to prove Hertz's equations incorrect? Why sould there be a problem with different ways of expressing the same thing? Over the course of six years of studying math, I came across at least four different variations on the "Fundamental Theorem of Algebra", each stated with a different hypothesis and a different conclusion,yet all really the same idea.
The theory that is most immune to refutation is, the one that relies on NOTHING to explain it. The "possible exception" being one which relies exclusively on "mathematical vectors."
You probably don't think it's a humorous as I do, but, then again, it aint my turf that's being attacked here. I aint no mathematician.
I don't think it's funny. Do you think that's out of anger because I disagree with Phipps or out of sadness because agree with him?
As I read him, he is making the same objection (with which you disagree) that I am making about any claim that sloping lines have ANYTHING (physical) to do with dancing bees.
Where did I make a claim that sloping lines have anything *physical* to do with dancing bees?
The "relativity of simultaneity," as I see it, is nothing special or distinct in itself. It merely follows from any supposed relativity of time and/or distance. Yet these authors often act like one explains the other somehow. It's like saying the conclusion proves the premise, and the premise proves the conclusion. Entirely circular and empty.
If the point of the page were to prove relativity, you would have a cogent point. Since the point is to illustrate aspects of something assumed to be a reliable model, your criticism is not really relevant.
How many "forms" of GR are there, I wonder?
I would be surpised if there were less than four. GR probably looks very different in different envronments and for different uses, even though they would all be reflections of a common set of ideas and equations.
One Brow said: "I think you, and probably Phipps, are also underestimating the appeal of the space-time symmetry in Maxwell's equations, that Phipps acknlwedges he must surrender for Hertz's variation."
Maybe Phipps is, but I aint, because I have no estimation whatsoever inasmuch as I really have no clue what the broad implications would be, either way. Phipps does seem to understand that a meaningful physical interpretation is important and does not appear to feel confident that he has one for Hertz's equations. But, what else is new? There is no established physical interpretation for SR, either, and Al didn't even attempt to advance one.
One Brow said: "However, relativity was inevitable, regardless of whether you use Maxwell or Hertz. It is the inevitable consequence of Galiean relativity and the constancy of light, both of which were experimentally confirmed."
Well, you could say the Lorentz transformations were inevitable, especially since they had already been devised before Al. And, of course, the relativity principle had been around for centuries.
But Al was trying to reconcile properties that were supposedly unique to electromagnetic phenomena, which is basically light. If the "constant speed of light" had it's own, self-contained, "explanation" within the framework of electromagnetic "theory" itself, why would there any need to mess with it when it comes to material bodies?
The thing you appear to keep overlooking is that, even now, there is no need to assume a "constant" speed of light (which is what I assume that you think is the essential part of "relativity" that is unavoidable). Assuming a preferred frame with a preferred time that other frames are "synchronized" to (as is done with the GPS) seems to work out just fine in both theory and practice. This allows at least theoretical speeds for light which exceed the absolute limit posited by Al, but so what? There is is simply no experimentally meaningful distinction between SR and LR, so SR is certainly not indispensable in that sense.
One Brow said: "[Relativity is] a model of how the universe actually works, and its creation was inevitable."
It's not clear just exactly what you intend to convey here, but talk about how the "universe actually works" always makes me suspicious. And, of course, there is always (with you) the question of what "relativity" you are even talking about. To me SR is "Einstienian relativity," not GR. Most all agree, Einstien included, that the inclusion of the term "relativity" in the "name" of GR is a misleading misnomer, and bascially inappropriate. The discussion we are having about Hertzian vs Mawellian electrodynamical equations has nothing whatsoever to do with GR (as opposed to SR) that I can see.
Would you also agree with this?: "[Lorenztian Relativity is] a model of how the universe actually works, and its creation was inevitable."
Somehow I doubt it, but I'm sure you see why I ask the question.
One Brow said: "It still means the galaxy is slower than c. If teh galaxy was faster than c, then the light would be moving away from us when it was released, and we wouldn't see it."
Well, Eric, this is the equivocation I was talking bout. The "speed of light" can be interpreted in two ways. One is simply the tautological "meaning" which is "the speed light travels at," and which would be independent of us having even the slightest clue as to what that speed is. This is a hollow, empty meaning, and is NOT the definition anyone uses in the context of physics.
Talk about objects receding from each other at a speed "faster than light" in physics is a claim that the distance between is increasing at a rate higher than 186,000 mps, that's all. Why pretend otherwise, or pretend that I can't even understand a tautology?
One Brow said: "Either way, the results appear the same to all observers. I agree that your example is a good reason why observations in science should be repearted often..."
Well, whether it's an example of that or not, that was not the point of the example. The basic point was to illustrate the difference between empirical conclusions (observations) and theoretical conclusions which depend up additional, freely created, non-empirical hypotheses.
The point is this--there is a definite difference between the following two statements, even if some can't see the distinction:
1. The sun IS the size of a man's foot, and
2. The sun can be measured (seen) as being the size of a man's foot.
All of your statements about how we have measured the "constancy" of the speed of light establish a proposition along the order of statement number 2 above, but they do NOT establish a statement along the order of statement number 1.
One Brow asked: "I don't think it's funny. Do you think that's out of anger because I disagree with Phipps or out of sadness because agree with him?"
The very fact that you asked this question, in this form, tells me what your answer would be. You would say its out of sadness because you agree with him.
But why be sad? Just yuk it up, like I do, ya know? I'm not kidding, this really does stimulate my sense of humor, and I can only chuckle.
But Al was trying to reconcile properties that were supposedly unique to electromagnetic phenomena, which is basically light. If the "constant speed of light" had it's own, self-contained, "explanation" within the framework of electromagnetic "theory" itself, why would there any need to mess with it when it comes to material bodies?
At some point, some one would have noticed that Galilean relaitivity did not apply to light, and tried to reconcile the two notions. When that happens, relativity will pop out. It was inevitable, not a feature of culture or a preferred way of thinking (although those could play a role in the when). You keep emphasizing the role that human creativity plays in developing theories, but now you seem to want to discard that role.
The thing you appear to keep overlooking is that, even now, there is no need to assume a "constant" speed of light (which is what I assume that you think is the essential part of "relativity" that is unavoidable).
What theories of relativity do not use the constancy of light? Please don't answer LET, which relies on the constancy of the two-way speed of light. With what other intuitive leaps do you think the constancy of light could be replaced, that do not imply the constancy of light. YOu need something else if you are going to create something that excludes Galilean relativity.
Assuming a preferred frame with a preferred time that other frames are "synchronized" to (as is done with the GPS) seems to work out just fine in both theory and practice.
Well, duh. That's one of the main ideas behind relativity theory.
This allows at least theoretical speeds for light which exceed the absolute limit posited by Al, but so what?
No, it doesn't. It allows for two separate objects, each with a speed below 299,792,458m/s, but going in different directions to that distance between them exceeds 299,792,458m/s. However, a disatnce between two objects is not itself an object, and certainly not limited to 299,792,458m/s. Nothing about choosing a preferred frame allows light to exceed 299,792,458m/s.
There is is simply no experimentally meaningful distinction between SR and LR, so SR is certainly not indispensable in that sense.
LR also relies on a limiting velocity for light, so there is no theoritical difference in that regard.
Would you also agree with this?: "[Lorenztian Relativity is] a model of how the universe actually works, and its creation was inevitable."
Somehow I doubt it, but I'm sure you see why I ask the question.
I don't know why you would doubt it. Are you saying LR is not an accurate model of the universe, or that there is some sort of creative force that would come up with SR, but not LR?
Well, Eric, this is the equivocation I was talking bout. The "speed of light" can be interpreted in two ways. One is simply the tautological "meaning" which is "the speed light travels at," and which would be independent of us having even the slightest clue as to what that speed is. This is a hollow, empty meaning, and is NOT the definition anyone uses in the context of physics.
That's because in the context of physics, the assumptions or homogeneity and isotropy are basically unquestioned. By these assumptions, the speed of light in a vacuum is 299,792,458m/s locally, so that's what is at the other side of the universe, and there is no need to distinguish between 299,792,458m/s and c.
However, you wish to remove homogeneity and/or isotropy, and have the speed of light move at different speeds in different parts of the universe. You've been trying to say all along that c is not necessarily 299,792,458m/s, but now I'm at fault for pointing out an elementary consequence of your position? If c is at some point not 299,792,458m/s, but is still constant locally and Galilean relativity still applies locally, then the Lorentz equations are still in effect with whatever value c has.
Talk about objects receding from each other at a speed "faster than light" in physics is a claim that the distance between is increasing at a rate higher than 186,000 mps, that's all. Why pretend otherwise, or pretend that I can't even understand a tautology?
Then, when I said that we would be unable to see such objects, why did you counter with a variable speed of light?
The point is this--there is a definite difference between the following two statements, even if some can't see the distinction:
1. The sun IS the size of a man's foot, and
2. The sun can be measured (seen) as being the size of a man's foot.
Absolutely. There is even a difference between:
1. The sun IS the size of a man's foot, and
2. The sun can be measured (seen) as being the size of a man's foot from a particualr point of view.
3. Regardless of all the different points of view we have tried to use to falsify the notion, the sun is always measured to be the same size as a man's foot.
While they are different, we often take 3. to indicate 1.
All of your statements about how we have measured the "constancy" of the speed of light establish a proposition along the order of statement number 2 above, but they do NOT establish a statement along the order of statement number 1.
False characterization.
But why be sad? Just yuk it up, like I do, ya know? I'm not kidding, this really does stimulate my sense of humor, and I can only chuckle.
Sometimes we get so sad we laugh, true enough.
One Brow said: "At some point, some one would have noticed that Galilean relaitivity did not apply to light, and tried to reconcile the two notions."
Well, you're overlooking the claim by Phipps, that if Hertz's equations had been used, the equations would have been 100% Galilean invariant, aren't you? There would have been nothing to reconcile. The Michelson Morley experiment would have had a ready-made explanation, provided by electromagnetic theory itself. That seems to be the claim.
One Brow said: "What theories of relativity do not use the constancy of light? Please don't answer LET, which relies on the constancy of the two-way speed of light."
We seem to be encountering some confusion about what the "constancy of the speed of light" is about. According to Al, the speed of light in a vaccuum is "constant" in two ways:
1. It is INVARIABLE, and constant in that sense, and
2. It is ABSOLUTE (cannot be exceeded) and constant in that sense also. Al himself noted that c "played the role of the infinite" in SR.
LR makes no such assumptions, whether 1 or 2, although it does acknowledge the curious fact that we always seem to MEASURE the speed to be the same. That is a "constancy" in measurement, perhaps, but it does not indicate, per LR, a true constancy of "actual" speed, just like me blocking out the sun with my foot does not make the size of the sun "actually" equal to the size of my foot.
An analogy:
It is an established fact that, as the temperature rises, a clock with a metallic pendulum will slow down. But this does not mean that "time" has slowed down, nor does it mean that the readings, as measured by an inaccurate clock, are accurate. Such a clock may give the "appearance" that only an hour has passed when it has actually been 65 minutes, but we would all presumably acknowledge that this anomaly is simply a deceptive appearance and not an accurate measurement of "underlying reality."
Moving at a relatively accelerated speed will, like temperature change, affect the readings of clocks according to LR, but that does not mean that "time" has changed, just the rate of clock ticking, that's all.
I actually thought we had discussed, and agreed upon, this difference between LR and SR before.
I said: "Assuming a preferred frame with a preferred time that other frames are "synchronized" to (as is done with the GPS) seems to work out just fine in both theory and practice."
You responded: "Well, duh. That's one of the main ideas behind relativity theory."
Yes it is. It is the main idea behind LORENTZIAN relativity theory. However, it is contrary to the supposed thesis of EINSTIENIAN relativity, which purportedly eschews "preferred frames" and denies the existence a "universal" time frame.
I said: "This allows at least theoretical speeds for light which exceed the absolute limit posited by Al, but so what?"
You responded: "No, it doesn't."
Well, Eric, once again you seem to forget a lot of our prior discussions about the differences between LR and SR.
Do you remember my relatively recent example where, from our (earth's) perspective a beam of light was 700 million miles from us after an hour, while a spaceship passing us at the exact moment the light beam was 350 million miles from us after the same hour?
As I said then, we would say that the beam of light was only travelling at .5c with respect to the spaceship. He would see it otherwise. According to LR the light really is only travelling .5c with respect to the spaceship, his erroneous measurments to the contrary notwithstanding.
But, actually, with SR, he would not be making "erronous" measurments, because he would not "assume" he was "at rest" when he knows he has been accelerated. After adjusting for the known effects of high speed motion on his rods and clocks, he two would conclude that he and the light beam are separating at the rate of only .5c, not c.
One Brow said: "LR also relies on a limiting velocity for light, so there is no theoritical difference in that regard."
I don't pretend to be well-versed in any of the variations of LR, and I don't think they all predict exactly the same thing. That said, I remember seeing one claim that, although there is no "theoretical" limit on the speed of light (i.e, there would be no violation of the "causality" principle if light--or more generally--information, went faster than 186,000 mps) that as a practical matter speeds exceeding 2c would not be anticipated. But the 2c "speed of light" would, according to LR, be the "actual" speed, not just an apparent one. Hence the theory rejects Al's constancy hypothesis.
One Brow said: "Then, when I said that we would be unable to see such objects, why did you counter with a variable speed of light?"
I don't recall doing this, but if I did, it's entirely consistent with me recognizing that the "speed of light" can have a (irrelevant for this purpose) tautological meaning, devoid of all content. I was NOT using that definition of c at any point, in anything I said.
One Brow commented: "3. Regardless of all the different points of view we have tried to use to falsify the notion, the sun is always measured to be the same size as a man's foot.
While they are different, we often take 3. to indicate 1."
Yes, "we" do. In fact SR explicitly does this, while LR does NOT do it. The point I was making is simply this: Taking 3 to indicate 1 is NOT a matter of empirical observation. It is a product of theoretical (hypothetical) premises that we ADD to the empirical observations.
A few quotes of possible interest, eh:?
"As the relativity of motion is taught today, Einstein’s special relativity has been observationally confirmed so often that there is no longer reason to doubt it...
The proof that faster-than-light (FTL) propagation is not allowed by nature is simple. Special relativity (SR) forbids it because, in that theory, time slows and approaches a cessation of flow for any material entity approaching the speed of light. So no matter how much energy is brought to bear, the entity cannot be propelled all the way to, much less beyond, the point where time ceases. The entity’s inertia simply increases towards infinity as the speed barrier is approached...
relativists are confident that SR is a valid theory because it has passed eleven independent experiments confirming most of its features and predictions. Moreover, the very successful theory of general relativity (GR) is based on SR, and has likewise passed several major experimental tests. So SR is confirmed by observations and forbids FTL propagation and travel...
Historically, de Sitter, Sagnac, Michelson, and Ives concluded from their respective experiments that they had falsified SR in favor of the Lorentz theory. [[†]] In each case, subsequent re-interpretation of SR allowed that theory to survive these objections. [from footnote]: De Sitter argued that the forward displacement of starlight (aberration) depended on absolute, not relative, speeds because both components of a double star, each with some unique velocity, had the same aberration. Sagnac argued that the fringe shifts expected but not seen in the Michelson-Morley experiment are seen if the experiment is done on a rotating platform. Michelson argued in the 1925 Michelson-Gale experiment that the Earth was just such a rotating platform. Ives argued that ions radiated at frequencies determined by absolute, not relative, motion because they had to pick a specific frequency to radiate at. In each case, a complex-but-now-familiar SR explanation could account for the same observed results."
Well, there ya have it then, eh?
http://metaresearch.org/cosmology/gravity/LR.asp
Well, you're overlooking the claim by Phipps, that if Hertz's equations had been used, the equations would have been 100% Galilean invariant, aren't you?
If Phipps is claiming that light follows relativity, to the point that an observer who is stationary sees light from a moving source as moving faster or slower compared to the light he emits, he's wrong. This notion has been tested. No matter how fast the light source is moving compared to the observer, the speed of light remains constant. In that particular fashion, light does not follow Galilean relativity. As I have pointed out before, all you have to do is put this together with Galilean relativity and you get the Lorentz equations, and relativity in general.
There would have been nothing to reconcile. The Michelson Morley experiment would have had a ready-made explanation, provided by electromagnetic theory itself. That seems to be the claim.
Since I am not basing my position on the need to reconcile something, but rather pointing out that even without that need for reconciling relativity was an eventuality, repeating that there would have been nothing to reconcile is not relevant.
We seem to be encountering some confusion about what the "constancy of the speed of light" is about. According to Al, the speed of light in a vaccuum is "constant" in two ways:
1. It is INVARIABLE, and constant in that sense, and
2. It is ABSOLUTE (cannot be exceeded) and constant in that sense also. Al himself noted that c "played the role of the infinite" in SR.
The absoluteness for massive objects is a result of relativity, not an initial postulate, and is equally true in any system that has teh Lorentz equations, including LR. The absoluteness for other, non-massive-yet-substantive phenomena (such as gravity waves) is not a part of SR at all.
LR makes no such assumptions, whether 1 or 2, although it does acknowledge the curious fact that we always seem to MEASURE the speed to be the same.
If LR did not use the constancy of light, it could not form the Lorentz equations. Look again at all the places "c" appears in the equations. If the speed of light is not a constant of some sort, the equations are random and unpredictable.
That is a "constancy" in measurement, perhaps, but it does not indicate, per LR, a true constancy of "actual" speed, just like me blocking out the sun with my foot does not make the size of the sun "actually" equal to the size of my foot.
If that really were true, LR would be no more of a theory than Newton had for gravity, just a random collection of equations that seemed to work.
Moving at a relatively accelerated speed will, like temperature change, affect the readings of clocks according to LR, but that does not mean that "time" has changed, just the rate of clock ticking, that's all.
In your analogy, an increase in temperature affects different clocks in different ways. However, if LET actually works as you are claiming it to, not only is every clock of every kind of construction affected the exact same way by moving through this ether, but the degree of this effect should change depending on the "true" local speed of light. There is no reason for mechanical and atomic clocks to be affected the same way, it just happens. There is no reason that this effect should always match c = 299,792,458m/s even when the object does not move in two directions, that just happens.
Yes it is. It is the main idea behind LORENTZIAN relativity theory. However, it is contrary to the supposed thesis of EINSTIENIAN relativity, which purportedly eschews "preferred frames" and denies the existence a "universal" time frame.
1. Saying something is not findable or not relevant to the problem at hand does not deny it's existence.
2. The ability to make an arbitrary choice as to the preferred inital frame is central tot he various uses of SR/GR we have discussed so far.
3. That, after all this discussion, you seem to think there is something about SR/GR that prevents you from choosing a reference frame in order to use them says you really, really don't understand anything we have been discussing. Really.
Do you remember my relatively recent example where, from our (earth's) perspective a beam of light was 700 million miles from us after an hour, while a spaceship passing us at the exact moment the light beam was 350 million miles from us after the same hour?
I don't remeber anything in that example about something exceeding c, and your recap brought out no such detail.
But the 2c "speed of light" would, according to LR, be the "actual" speed, not just an apparent one. Hence the theory rejects Al's constancy hypothesis.
Again, if it does not treat the two-speed as a constant, then there are just a bunch of unrelated equations.
I don't recall doing this, but if I did, it's entirely consistent with me recognizing that the "speed of light" can have a (irrelevant for this purpose) tautological meaning, devoid of all content. I was NOT using that definition of c at any point, in anything I said.
Again, if it does not treat the two-speed as a constant, then there are just a bunch of unrelated equations.
Yes, "we" do. In fact SR explicitly does this, while LR does NOT do it.
Of course LR does it, just to a lesser degree. Otherwise it couldn't say light was faster than a tortoise, because the next time someone lit a flashlight, the light from it might be slower than the tortoise.
The point I was making is simply this: Taking 3 to indicate 1 is NOT a matter of empirical observation. It is a product of theoretical (hypothetical) premises that we ADD to the empirical observations.
Well, of course is. If you hadd nothing to the observations, all yo have is a bunch of data lying around.
A few quotes of possible interest, eh:?
...
Well, there ya have it then, eh?
So, theories aren't supposed to accomodate experimental data? That would be a strange science, indeed.
Hmmm, where to start? How about at, or near, the end?
One Brow said: "Well, of course is. If you hadd nothing to the observations, all yo have is a bunch of data lying around."
"Is" what? A product of theory, or simply an empirical observation (or "fact"). It seems you are agreeing with me, but I'm not 100% sure.
If you are, fine. We won't have later argue about any appearance that you are suggesting that scientific theories are "empirical observations."
You asked: "So, theories aren't supposed to accomodate experimental data? That would be a strange science, indeed."
Did you go to the website and read the full article? It appears to give answers to some of the questions propounded in your last post.
For example, you say: "No matter how fast the light source is moving compared to the observer, the speed of light remains constant. In that particular fashion, light does not follow Galilean relativity. As I have pointed out before, all you have to do is put this together with Galilean relativity and you get the Lorentz equations, and relativity in general."
1. Waves do not, in general, follow the same "rules" as particles in Galilean relativity, but that's nothing new. The speed at which a wave propogates is always independent of the speed of it's source, or so they say.
2. The formulas listed there for LR contain no reference to c. That said, even the Lorentz tranformations reduce to Galilean relativity at speeds not approaching c to begin with. So we're really only dealing with electromagnetic phenomena as being somehow "different" as a practical matter. I don't understand exactly how Hertz's equations "explain" the Michelson-Morley (and similar) results to begin with, but the claim is that they do. Such a result would be expected by, and predicted by, Hertz's equations, Phipps says.
aintnuthin said...
If you are, fine. We won't have later argue about any appearance that you are suggesting that scientific theories are "empirical observations."
Why would we have ever argued about that? Scientific theories are based on, restricted by, and guided by empirical, but I have never said they were empirical.
1. Waves do not, in general, follow the same "rules" as particles in Galilean relativity, but that's nothing new. The speed at which a wave propogates is always independent of the speed of it's source, or so they say.
So, you think light is constant, then?
2. The formulas listed there for LR contain no reference to c.
Of course, c is present in the formulas not listed in the table for how much the clocks slow down and the rulers shrink, formulas pointed out higher up in the page as the Lorentz trnasformations. You remember, teh ones that are the same for SR and LR.
That said, even the Lorentz tranformations reduce to Galilean relativity at speeds not approaching c to begin with.
Depends on the speed and the accuracy of the measuring device.
So we're really only dealing with electromagnetic phenomena as being somehow "different" as a practical matter. I don't understand exactly how Hertz's equations "explain" the Michelson-Morley (and similar) results to begin with, but the claim is that they do.
Again, I really don't see how this is relevant to whether SR was going to be developed or not.
One Brow said: "If that really were true, LR would be no more of a theory than Newton had for gravity, just a random collection of equations that seemed to work."
Like SR is, ya mean? I don't see how your conclusion follows. As I have said before, physics, for better or worse, is a discipline which presupposes an "objective reality" that is independent of the subjective perceptions of any given individual.
As such, it aspires to describe the "true" causes and effects of matter in motion, etc. As noted, Galileo used the relativity principle (which presupposes the law of inertia), to help explain why deceptive appearances do not dictate "reality."
LR, unlike SR, attempts to explain, in a rational, physical way, why things appear to us as they do. That is not just a "random collection of equations." There is, no doubt, a formula which captures the degree to which a metal pendulum lengthens with temperature increases, thereby affecting the period of its oscillation. That is not a random collection. The equations are coupled with a theoretical PHYSICAL (not merely mathematical) explanation of the changes being quatified.
One Brow said: "In your analogy, an increase in temperature affects different clocks in different ways. However, if LET actually works as you are claiming it to, not only is every clock of every kind of construction affected the exact same way by moving through this ether"
Exactly, that's the claim. It has nothing to do with clock construction per se, it has to do with the frequency of recurrent events. As I understand it, all matter, regardless of composition, ceases all motion at absolute zero. But only a formalist would claim that this means "time itself" stops. Our standard methods of MEASURING time would stop, sure, but "time itself?"
For LR adherents, time is not a thing, it is a dimension. It is a mental construct, a concept, not a physical force or entity. As such, it cannot be "stopped" by temperature changes or anything else. It doesn't even exist in a "physical" realm.
One Brow asked: "So, you think light is constant, then?"
I didn't say that, I just said that the speed of light does not depend on the speed of it's source. The claim that the speed of light is also independent of the speed of an observer is what I aint buyin.
As I understand it, the GPS system, as constructed and implemented, has ONLY ONE frame in which the speed of light is constant, i.e. the preferred ECI frame. The speed of light for the satellites, guys driving around in cars, etc. varies. This is because the clocks are synchronized to the ECI frame. The method of synchonization used dictates such things, not "light itself."
Like SR is, ya mean?
Like neither SR nor LR, actually.
LR, unlike SR, attempts to explain, in a rational, physical way, why things appear to us as they do.
You think SR is not rational or not physical? *chortle*
That is not just a "random collection of equations." There is, no doubt, a formula which captures the degree to which a metal pendulum lengthens with temperature increases, thereby affecting the period of its oscillation. That is not a random collection.
Yes, because the equation is tied to an explanation of how the heat affects the pendulum.
The equations are coupled with a theoretical PHYSICAL (not merely mathematical) explanation of the changes being quatified.
The physical explanation that LR gives for the slowing down of every clock in an identical manner (compression of atoms) does not make sense when the molecular structure of these cloacks varies to greatly.
Exactly, that's the claim. It has nothing to do with clock construction per se, it has to do with the frequency of recurrent events.
That is the problem I am pointing out. Anything physical, like ether is supposed to be, interacting with other physical things will interact with them differently, according to their components.
As I understand it, all matter, regardless of composition, ceases all motion at absolute zero.
Yet, you are not claiming ether has the same mechanism as a temperature drop, but merely making yet abnother bad analogy.
For LR adherents, time is not a thing, it is a dimension. It is a mental construct, a concept, not a physical force or entity.
If time were nothing but a mental construct, it would have no physical implications. Everything would be instantaneous. A coordinate system to measure time is a mental construct, time is not.
I didn't say that, I just said that the speed of light does not depend on the speed of it's source. The claim that the speed of light is also independent of the speed of an observer is what I aint buyin.
What sort of experiment would convince you this is true?
So the question is not simply "is the speed of light constant," but rather, is it constant in all inertial (or non-inertial, for that matter) frames?
As I understand it, the GPS system, ...
You mean, as Van Flandern explains it. The GPS clocks, when on earth, run more slowly that other atomic clocks. They get adjusted as their orbits change. Their programming is fully SR/GR. How many links would you like confirming this? Here's one:
http://www.brighthub.com/science/space/articles/32969.aspx
Constant in all non-interial frames? I'm not sure that's a postulate of SR/GR.
The wiki page limits it to inertial frames:
The speed of light, usually denoted by c, is a physical constant important in many areas of physics. Light and all other forms of electromagnetic radiation always travel at this speed in empty space (vacuum), regardless of the motion of the source or the inertial frame of reference of the observer.
One Brow said: "The physical explanation that LR gives for the slowing down of every clock in an identical manner (compression of atoms) does not make sense when the molecular structure of these cloacks varies to greatly."
Molecular structure? As I understand it, current theory seems to think that at its most basic levels, matter is just the same damn stuff, on both the atomic and sub-atomic levels. That "same stuff" may simply be strings, I dunno.
Again, theory seems to be that the frequency of ALL recurrent events becomes ZERO at absolute zero temperature, regardless of "molecular structure." I'm not gunna try to explain "why" this is, because I don't have the background or knowledge to even understand it. Why should reduced temperatures slow things down? I dunno...why can light itself be slowed to 38 mph in extremely cold temperatures? I don't know. But they say these things actually do, or at least would, happen. And, no doubt, there are at least hypothethical reasons for believing they do.
I won't try to explain why speed should effect frequencies anymore that I do why temperature supposedly does. It's all a mystery to me. That doesn't mean it doesn't happen. Maybe you understand exactly why it CAN"T happen. If so, please tell. As far as I know, experiments have showed that clocks do slow down with increased speed, and this is supposedly consistent with SR theory and predictions, but maybe you know something I don't.
Correction:
Van Flandern does use c in his LR equations in the table on his page, they are hidden behind the greek letter gamma.
gamma = 1/sqrt(1 - (v^2)/(c^2))
One Brow said: "You mean, as Van Flandern explains it. The GPS clocks, when on earth, run more slowly that other atomic clocks. They get adjusted as their orbits change. Their programming is fully SR/GR. How many links would you like confirming this? Here's one:
Van Flandern explains it just like everyone else who knows what they are talking about explains it. "Fully" SR/GR? What does that even mean, do you think? The synchronization method is not "SR," it is LR, so why not say it is "fully LR/GR?
That "same stuff" may simply be strings, I dunno.
Same stuff, different arrangements, different effects.
Why should reduced temperatures slow things down?
Because heat *is* molecular movement, and removing heat is accomplished by stilling the movement.
As far as I know, experiments have showed that clocks do slow down with increased speed, and this is supposedly consistent with SR theory and predictions, but maybe you know something I don't.
While I know you are loathe to regard time as a physical entity, how would you feel about thinking of it as a part of a path? Just as a path goes through space, we also follow a path through time. If you think this is an idea you might be willing to embrace, it's quite possible to explain the effects of SR and not operating on the clocks themselves, but rather the clocks being taken on a different path. In other words, just like your actions can control your spatial path, they can control your temporal path.
One Brow said: "Correction:
Van Flandern does use c in his LR equations in the table on his page, they are hidden behind the greek letter gamma.
gamma = 1/sqrt(1 - (v^2)/(c^2))"
OK, thanks for the correction. Those symbols mean nothing to me, so I would not know.
One Brow asked: "While I know you are loathe to regard time as a physical entity, how would you feel about thinking of it as a part of a path?"
On principle, I have no objection to "thinking about" things in any given way, no matter how formal, abstract, or apparently divorced from physics as physics. But that doesn't mean I will accept strictly mathematical conceptions as a "physical" explanation.
I can, for example, "think about" a bees dance as being represented in a geometrical model on graph paper. All very interesting, to be sure, but...
I'm sure Phipps could "think about" magnetic and electrical fields as being "fabricated by" mathematical vectors, too. That wasn't the basis of his objection to what he was "taught" as I understand him.
One Brow said: "That is the problem I am pointing out. Anything physical, like ether is supposed to be, interacting with other physical things will interact with them differently, according to their components."
Really? Then why doesn't gravity interact differently with objects, depending on their composition?
Van Flandern is making a claim about GR here that I am not qualified to evaluate, but it sounds credible, at least:
"Conspicuously missing from the list of experimental results is any experiment testing reciprocity of the Lorentz transformations. Specifically,Conspicuously missing from the list of experimental results is any experiment testing reciprocity of the Lorentz transformations. Specifically, GR is built on SR using only one-way Lorentz transformations relative to the local gravitational potential field (center-of-mass reference frame), which can be identified physically with “elysium” (the light-carrying medium). [[v]] GR is therefore just as consistent with LR as is SR. (center-of-mass reference frame), which can be identified physically with “elysium” (the light-carrying medium)." GR is therefore just as consistent with LR as is SR."
This is the part I am emphasizing: "...GR is built on SR using only one-way Lorentz transformations relative to the local gravitational potential field..."
GR uses only "one-way" and not reciprocal Lorentz transformations? Sound right to you?
I don't know how that quote got so messed up, but you can read it youself if it's too confusing to be intelligible with all the random repetition my redention contains, eh?
I said: "I didn't say that, I just said that the speed of light does not depend on the speed of it's source. The claim that the speed of light is also independent of the speed of an observer is what I aint buyin."
One Brow asked: "What sort of experiment would convince you this is true?"
It's not a matter of "experiment," it's a matter of meaningful physical explanation. No experiment is "self-explanatory," so experiment alone is not even the issue. I can agree with the "results" of all the experiments that "confirm" SR. I am not questioning those results, I'm just not satisifed with SR purported "explanation" of why they occur. It's not even an explanation, just an ipse dixit postulation that has not been, and presumably cannot be, experimentally demonstrated.
Another analogy. I assume that we can agree that, just as with SR vs LR, both heliocentricism and geocentricism can and do make the same predictions as far as "observable phenomena" goes, but they differ dramatically in their respective explanations of "why" things appear as they do.
That said, the explanations do NOT make an equal appeal to common sense as filtered by other things we have reason to believe. I don't think *any* experiment could convince me that geocentricism provides a "more reasonable" explanation of the phenomena than does heliocentricism. All the same, there is no experiment which, by itself, could "disprove" a geocentric premise.
But that doesn't mean I will accept strictly mathematical conceptions as a "physical" explanation.
Since what I am talking ab out will treat time as a dimension, it won't be "physical" in that sense. However, the hard part is, can you accept time as being a dimension, in the same way that space has three dimensions? In particular, can you see changing your path in time, much as you change your path in space, as being a real phenomenon? Or, do you see time as completely different than spatial dimensions? I am not talking about a mathematical construct, I mean time as we experience it.
Really? Then why doesn't gravity interact differently with objects, depending on their composition?
Gravity is a physical object? Or, is ether supposed to a force with no physical presence?
GR uses only "one-way" and not reciprocal Lorentz transformations? Sound right to you?
Not really, but he could mean a couple of different things, so I'm not sure. If he's referring to the equations, they are self-invariant, so there is no such thing as one-way invariance. If he's referring to the notion that we have not accelerated a laboratories to high rates of speed and then looked for Lorentz effects on ground (so we have only tested them one way), that could be true. But I think he means that in developing GR, you look for Lorentzian-type effects of the gravitational field (changes in time passage, etc.), but you don't look for the gravitational field to be altered by the speed of an object passing through it. I don't know why you would look for such an effect.
As for his claim that LR is compatible with GR, I have no doubt that this is true for the equations, although I thinks the theories are probably irreconcilable.
It's not even an explanation, just an ipse dixit postulation that has not been, and presumably cannot be, experimentally demonstrated.
I agree. It's an inductive leap based on the results of experiements, and can not be proven (although it can be demonstrated in the particular).
I don't think *any* experiment could convince me that geocentricism provides a "more reasonable" explanation of the phenomena than does heliocentricism. All the same, there is no experiment which, by itself, could "disprove" a geocentric premise.
In the sense you can always add ad-hoc reasons to explain phenomena like Focault's pendulum, that's true. The actual disproof comes notions like conservation of energy, which itself is another intuitive leap from experimental evidence.
One Brow asked: "In particular, can you see changing your path in time, much as you change your path in space, as being a real phenomenon? Or, do you see time as completely different than spatial dimensions? I am not talking about a mathematical construct, I mean time as we experience it."
Yes, I see it as completely different. Don't get me wrong here, because I also see how it can be mathematically and geometrically "treated" as either it's own dimension or as a mongrelized component of a combined space and time (spacetime). I further see how this can provide some convenient mathematical shortcuts when making calculations, etc. So I don't argue with the formal validity of such views and techniques.
But, as I have indicated, it is utterly nonsenical (to me) to suggest that "time causes gravity." By that I mean, it just doesn't carry any intelligible meaning to me in a physical sense. Just as comprehensible would be a claim like "the sun crosses the sky because it is pulled by Mercury in a chariot."
Actually, the Mercury claim would be much more "comprehensible," as far the clarity of the meaning intended to be conveyed. But they would be equally unsatisfactory as an acceptable "explanation" of the events in question.
Any numerologist sect might have seemingly plausible explanations for asserting something like: "5, being the combination of 2 (which corresponds to universal ying and yang) and 3 (which has historically represented conflict due to imbalance) is a moderating number which can resolve many conflicts, create unity from duality, and help effectuate peace on earth."
I just made all of that up as I went along, but there are people so immersed in a particular way of analyzing things from a particular view of "reality," that they might well find such claims to be quite reasonable and persuasive.
I wouldn't. And, for me, the propositions that space and time are "things" which "cause" physical reality is just as metaphysically obtruse and absurd. I acknowledge the "reality" of space and time in a certain sense, but not with that kind of ontological priority.
I'm just kinda shootin from the hip here, but I don't see how we could have any concept of "time" without change. If "reality" were really nothing more than an eternally static, immutable, Parmenidean "being" (as constrasted with "becoming"), we couldn't be cognizant of "time." Kinda like we would have no concept of "night" if everything were just one long eternal "day."
So change and contrast are essential to our conception of "time" as I see it. Now, as for measuring, or quantifying, "time" we must rely on what seem to be regularly recurring events that appear to happen with a constant frequency. The earth completes a full rotation every (sidereal) day, complete a full revolution about the sun every (sidereal) year, so these become "standard" and "reliable" recurrences.
In truth, I believe that the earth's speed in it's revolutionary orbit varies during the year, and the exact duration of a rotation probably varies some too, so these are not ideally equal periods. But they're close.
And in that sense, a "day" has a real, physical meaning. If we divide it up into parcels of hours, minutes, seconds, etc., those parcels retain their "objective' meaning. So time is not merely a subjectively measured concept which actually "flies" when you're having fun and "drags" when you're in a dentist's chair.
If the speed of the earth's rotation increased by, say, 10%, we might not have any objective way of knowing it even if we thought we subjectively detected some difference from "yesterday" by virtue of our "biological clocks."
So what? Well, so, as I see it, mechanical clocks, atomic or otherwise, do not, and cannot directly meaure "time," as such. We merely calibrate them to count the frequency of certain recurring events that we deem to be "equal" in duration, such as an electron's orbit in a celsium atom.
They do not measure "time" per se. Even less so does "time" control them. "Time" is not some all-powerful dictator, capable of bullying all and compelling compliance with it's whimsical changes. If some change in the physical environment of a "timepiece" occurs which changes the duration of the recurring events which we have previously supposed would remain "equal" then it will not give us the expected outcomes we had in mind when designig them. A pendulum clock exposed to heat, for example.
We've talked about this before. Same with distance. Wearing an inch off the tires on your car will decrease their diameter, which will in turn perhaps cause your odometer to indicate that the distance to the post office, formerly 10 miles, is "now" 10.3 miles. But the distance to the post office has not changed.
For such reasons, I find it absurd to claim that "time," as some kind of independent entity, controls how clocks measure it. Such a conception is completely backwards, not to even mention metaphysically unsound.
Edit: I said: "We merely calibrate them to count the frequency of certain recurring events that we deem to be "equal" in duration, such as an electron's orbit in a celsium atom."
This was poorly worded. What I really meant was "We merely calibrate them to count the RAW NUMBER [not "frequency"] of certain recurring events that we deem to be "equal" in duration, such as an electron's orbit in a celsium atom."
One Brow said:
"1. Saying something is not findable or not relevant to the problem at hand does not deny it's existence.
2. The ability to make an arbitrary choice as to the preferred inital frame is central tot he various uses of SR/GR we have discussed so far.
3. That, after all this discussion, you seem to think there is something about SR/GR that prevents you from choosing a reference frame in order to use them says you really, really don't understand anything we have been discussing. Really."
Finally, after all these millions of posts, we are kinda gittin to the bottom of all the dispute.
As for your number 1, this is true, and is a point I tried repeatedly, without success, to get you to acknowledge a year or so ago.
As for 2 & 3, I made a post earlier in this thread that you probably didn't even read. To what extent are the supposed "differences" between SR and LR actually implied by the physical theory, as opposed to simply being philosophical add-ons imported without necessary cause? I don't really know.
Van Flandern makes a contrasting list of differences between LR and SR, but are these valid differences of the actual theories, or just a reflection of more-or-less arbitrary "explications" of the math involved?
I'm no longer sure. The post I referred to discussed a theoretical physicist (philosopher of science, maybe) who purported to prove that, operationally speaking, SR and LR were literally "identical" theories. He didn't just mean that they made identical predictions, but rather that whatever one might imply (if anything) about the nature of space or time, about the constancy of the speed of light, the existence/non-existence of ether, or any other matter, the other also necessarily implied.
I have heard so many different claims about what SR "tells" us about such things that they can't all be true, because some contradict each other. And when I say "heard" I mean read on presumably reputable .edu websites sponsored by major universities, and the like.
I still haven't reflected on it enough to form my own conclusion, but I suspect his claims may well be true. The supposed "differences" might not be part and parcel of necessary implications of the respective theories, but more just an expression of the preferences of a particular advocate.
I have seen, for example, "relativists" explain the theory by saying that clocks and rulers "really" change with speed. It seems to me that the "relativity of simultaneity" site you referenced made such a claim (i.e., that length contraction is "real"). Does that mean "distances" really change? If so, would that include the "rulers?" If the "rulers" really change, then, in a sense, the distance hasn't, but our means of measuring distance has. How could it even be one without the other? How could a yardstick remain inviolate while "speed" caused the "distance itself" to change? Why would the "change of distance" be selective in that way?
I can't buy the claim that the "distance" to a star is immediately cut in half by accelerating to a speed near that of light. I can believe that the time it takes to get there changes (shortens) sure, but the actual distance?
If, as you seem to suggest, one can immediately turn SR in LR by arbitary choice, then how can there be a "real" difference? Doing that would simply import all the "LR" assumptions into SR and make it comprehensible. All the "mystical," metaphysically dubious, claims associated with SR would just disappear.
Is a single "innocent" theory of relative motion merely being artificially divided into two supposedly "different" theories, with each "half" being enslaved and impressed into "service" by those with different philosophical views to promote?
Maybe.
Yes, I see it as completely different.
OK, you see a fundamental difference in time as a dimension versus other three dimensions of space. However, you don't go on to specify what that difference is. Is there anyting more to the difference than you can move freely back-and-forth across a distance, but not across a time period?
But, as I have indicated, it is utterly nonsenical (to me) to suggest that "time causes gravity."
I have no intention of going there.
I wouldn't. And, for me, the propositions that space and time are "things" which "cause" physical reality is just as metaphysically obtruse and absurd. I acknowledge the "reality" of space and time in a certain sense, but not with that kind of ontological priority.
How do you see time and space differing?
So time is not merely a subjectively measured concept which actually "flies" when you're having fun and "drags" when you're in a dentist's chair.
OK.
If the speed of the earth's rotation increased by, say, 10%, we might not have any objective way of knowing it even if we thought we subjectively detected some difference from "yesterday" by virtue of our "biological clocks."
Or comparison to other, independent measurements. If you have 50 different, independent things that time to a day (so they are all in agreement), and sudeenly one of the goes out of agreement while the other 49 do not, the natural conclusion is that the odd duck is the one that changed. Aklthough, I suppose you could say that is a subjective preference.
They do not measure "time" per se. ... Same with distance.
So far, your description have made time sound very much like distance. What about them makes you think they are so dissimilar?
As for your number 1, this is true, and is a point I tried repeatedly, without success, to get you to acknowledge a year or so ago.
You mean, I claimed that relativity means an absolute reference frame could not exist (as opposed to could not be detected within relativity)? What remarkably poor wording on my part.
As for 2 & 3, I made a post earlier in this thread that you probably didn't even read.
If it's relevant now, repost it and I'll read it, as long as the wieght of text is not crushing.
I have heard so many different claims about what SR "tells" us about such things that they can't all be true, because some contradict each other. And when I say "heard" I mean read on presumably reputable .edu websites sponsored by major universities, and the like.
I'll grant you that many interpretations seem to contradict each other.
I can't buy the claim that the "distance" to a star is immediately cut in half by accelerating to a speed near that of light. I can believe that the time it takes to get there changes (shortens) sure, but the actual distance?
What if that acceleration puts you on a different path? Could taking a different path shorten your trip?
Is a single "innocent" theory of relative motion merely being artificially divided into two supposedly "different" theories, with each "half" being enslaved and impressed into "service" by those with different philosophical views to promote?
Maybe.
You know, you could be on to something there.
One Brow said: "How do you see time and space differing?"
Well, the answer to that seems obvious to all. It is only when you try to make "speed," which is a product of time and distance, and which is hence a resultant quantity (rate, actually), into the PRIMARY thing that such indiscriminate and misguided "blurring" of the two occurs.
I have already noted the utter circularity and logical inconsistency of attempting to actually DEFINE distance as a result of speed, rather than vice versa. You can't know the speed until you know both the time and the distance, but with the thinking applied by relativists, you only know the distance BECAUSE you "know" the speed beforehand.
I made the same point with the physicist who was explaining (as Al did) how "distance" is "known" (postulated actually) by observing light.
One Brow said: "What if that acceleration puts you on a different path? Could taking a different path shorten your trip?"
This talk about "paths" just doesn't compute. If I want to reach a town 10 miles east of me, the path I take can obviously make a major difference. I would be foolish to head west and keep going until I eventually get there. But acceleration would be totally irrelevant to that "difference."
A "path" through a forest I can understand, a "path" through time makes no sense. It's like talking about the size of a color.
One Brow asked: "So far, your description have made time sound very much like distance. What about them makes you think they are so dissimilar?"
Who doesn't think they are different? Even if I'm talking about speed, they are obviously two very different things which are not "interchangable."
Let's say I run a 100 yard dash in 10 seconds. The units of distance are defined, measured, and established by using lengths. The units of time are estabished by, for example, dividing a day into supposedly different parts, and measured by a timekeeping piece (a stopwatch, for example). The "10 seconds" are of an entirely different order than are the "100 yards." The "speed" would be the same if I ran 200 yards in 20 seconds, but even people who can run 100 yards in 10 seconds can't run 200 yards in 20 seconds, so you can't just extrapolate "speed."
That's a sidepoint, though. The main point is that you must know BOTH time, and distance, as distinct things, before you can ever know "speed." If they are "the same thing," then the whole concept of speed is meaningless.
Meant so say: "The units of time are estabished by, for example, dividing a day into supposedly EQUAL (not "different") parts, and measured by a timekeeping piece (a stopwatch, for example).
Well, the answer to that seems obvious to all.
Isn't that the type of answer you usually distrust?
A "path" through a forest I can understand, a "path" through time makes no sense. It's like talking about the size of a color.
We call the directions in space dimensions (three of them), and the direction in time a dimension. You clearly think there is something fundamentally different in the time dimension that makes shortcutting through it not possible. Why? Is it just a brute reality for you, with nothing behind it?
Who doesn't think they are different?
There is the difference that you can reverse direction in one, but not the other. I'm asking if you see any other fundamental differences.
That's a sidepoint, though. The main point is that you must know BOTH time, and distance, as distinct things, before you can ever know "speed." If they are "the same thing," then the whole concept of speed is meaningless.
A scale factor is a distance divided by a distance (such as 1 inch to 50 miles). I assume you think a distance is much more "the same thing" as another distance than any version of time would be to distance. Yet, I don't think you believe scale factors are meaningless. So, I don't think you should assume speed is meaningless simply because time might be a dimension interconnected with the three dimensions of space.
One Brow said: "So, I don't think you should assume speed is meaningless simply because time might be a dimension interconnected with the three dimensions of space."
I didn't say it was meaningless. To my knowledge, whatever other modern innovations in physics might entail, the definition of speed as distance travelled divided by time elapsed has not changed.
My point is simple, and I have made it repeatedly: By definition, you cannot know the speed unless and until you first know the distance travelled and the time elapsed. If you ALREADY know the speed, then, of course, you can deduce the distance travelled if you know the time elapsed and the time elapsed if you know the distance travelled.
But, again, you wouldn't "already know" the speed unless you knew those components to begin with, so there is no need or call for "deducing" time or distance. You just measure, not "deduce," time and distance. Well, unless you're a relativist, maybe.
This is truly a side note, but on a practical level, you can use speed measured from a smaller ratio, along with a time traveled, to measure an unknown distance. It does require an additional assumption of isotropy, but that is standard. For example, if you have a robot that travels 1 mile per hour, which you have painstakingly verifed on smaller distances you have measured, and set him loose to cross a plain, you don't need a fifteen-mile measuring tape when the robot crosses the plain in 15 hours.
I agree that the notion of speed is dependent on some level as measuring a distance and a time, but calculating a distance from a speed and a time, or a time from a speed and a distance, is not just a formal exercise, it has practical applications. It is useful.
However, that's a distraction. Your example still treated distance and time as basically having equal status in forming speed, so it was not useful in determining what differences you think there are between distance as a dimension and time as a dimension, beyond the difference that you can reverse direction in one, but not the other. Again, is this fundamental difference some brute fact you just accept? Do you propose any other fundamental differences.
One Brow asked: "Your example still treated distance and time as basically having equal status in forming speed, so it was not useful in determining what differences you think there are between distance as a dimension and time as a dimension"
I'm not even sure what you mean by "time as a dimension" vs "space as a dimension." Time and space can be represented as "dimensions" on a graph, but that's not what they "are." In one sense, every dimension is equal to every other "as a dimension" if you're just talking about mathematical concepts, as opposed to actual times and distances in a physically meaningful setting.
There is a physical distance associated with a football field, and an amount of elapsed time associated with one complete rotation of the earth. Neither of those things is a "dimension" in a geometrical model.
That's the whole point. Although you can perhaps symbolize or "represent" distance and/or time in a geometrical model, the symbols and representationss are NOT time and distance. Any talk that treats them as equivalent is a language I don't understand.
I mean, I might in an unthinking way, point to a "purple" patch on a model globe and tell a child "That is the united states." But, in any physically meaningful sense, it is obviously NOT the U.S. It is merely a purple-colored area on a small ball.
The kid might take me literally and thereafter think that the "united states" refers to that patch on that ball, but that's only because I have failed to properly communicate my intended meaning to him. If I explain it properly, but he nonetheless continues to believe that the purple patch literally "is" the U.S., well, then, that's on him, not me.
There is a physical distance associated with a football field, and an amount of elapsed time associated with one complete rotation of the earth. Neither of those things is a "dimension" in a geometrical model.
I don't recall asking if they were dimensions in a geometric model. Is that your method of saying that they are at a brute level fundamentally different and dissimilar, and any similarities in how they are treated are facets of the treatment and not the reality the treatment is trying to model? Or, were you just objecting to the word "dimension"? Do you think there are any fundamental similarities to one aspect of reality that we measure by counting ticks on a ruler, and another we measure by counting ticks on a clock? If so, what sort of similarities would you recognize?
Now, if I noted that statistics show a significant increase in the recent number of mexicans immgrating into the U.S., and if the kid tried to "explain" this phenomena by saying that it is well known that purple is the favorite color on the average mexican, and that's why they are coming here, I would just laugh.
One Brow asked: " Or, were you just objecting to the word "dimension"?
I merely said I don't know what you're getting at when talking about space or time "as a dimension."
You can generally find some limited and imprecise "similarities" between any two things, even if they are generally quite dissimilar. Humans are "similar to" both tapeworms and plants in that they are all "alive," for example. Is there something in particular you're trying to get at that you think is significant?
Great. Now that we've established that you don't want to confuse models of time with time, and models of space with space, can you expand a little more on what you see as the fundamental differences (and similarities, if you recognize any) between time and length?
Is there something in particular you're trying to get at that you think is significant?
There are two or three different places I think I could take this conversation to, depending what sort of notions youdo or don't accept can apply to being real notions. So far, I;m seeing a lot of what you don't accept, but very little of what you do accept.
For example, were you saying that any similarity between distance and time is "limited and imprecise" because they are fundamentally different, with few genuine similarities?
I could, if I devoted my existence to it come up with, a list of at least a 100 things that could be considered "similiar" between space and time and at least 100 that are dissimilar (although they would just reduce to the same types of things).
I have already said that I consider BOTH distance (more generally "space") and time to be abstract concepts, NOT spatially extended "things," and not "forces", theoretical or otherwise, which "act on" matter in motion. In that sense they are similar to each other, and dissimilar from physical objects.
I have also said that, even though they are mere abstract concepts, they do have physical counterparts which "exemplify" or "instantiate" them in the physical realm. I could go on, maybe, but I don't care to. Is there a point you want to make, or a particular question you want to ask to clarify what I'm sayin?
Let me ask you a question or two, Eric. Take this scenario:
Two people are playin catch with a baseball on a large military cargo-carrying jumbo jet, which itself is travellin east at the rate of 500 mph relative to the earth. They are, needless to say, at least "apparently" motionless with respect to each other. Now they throw the baseball back and forth to each other at the rate of 100 mph(in the jet's inertial frame). As perceived by the players, will the ball travel faster when thrown toward the front of the plane from the rear than it does when it is thrown toward the rear of the plane from the front?
... , they do have physical counterparts which "exemplify" or "instantiate" them in the physical realm.
Since I'm tryong to explain a phenomenon as it would be instantiated, I'm much more interested in what you think of how the physical counterparts may or may not interact than of the abstract concepts. Of course, if you prefer not to elucidate, fine.
The answer to your question is no, as long as the players only look at what is in the plane. The players will see no difference in the speed of the ball, unless they compare it to something outside of the plane.
One Brow said: "Since I'm tryong to explain a phenomenon as it would be instantiated, I'm much more interested in what you think of how the physical counterparts may or may not interact than of the abstract concepts. Of course, if you prefer not to elucidate, fine."
Well, it still not clear to me what you are trying to understand (about what I think). "Distance," as a term, is merely an abstraction. Take two goalposts, whether 10 yards apart, 100 yards, or two feet, it doesn't really mater.
We see that they are not in the exact same place. We therefore say they are separated from each other. By what? Well, space, which we might also call distance, inasmuch as there is a distance between them. If we want to try to quantify just how small or great that distance is, then we will contrive to design "standard" distances, such as those measured by a ruler or yardstick and count em up. This has the convenience of being able to compare the proportion of two (or more) different distances which may be in other locations or not readily apparent.
Just looking at a post which is 100 yards away from me and one which is 99.5 yards away from me in another direction, I would be hard pressed to know which one is farher away, if either. But, if I really want to know, I can measure each distance separately, then compare the result.
My metaphysical presumption would be that if two goalposts are 100 yards apart today, and no one moves them (and they don't move themselves) then they will also be 100 yards apart tomorrow. The notion that the space, or distance, between them could just up and expand without them moving would not occur to me.
Granted, an earthquake could disturb the earth, perhaps pushing them farther apart, but it that case they will have moved. As long as they don't move, they are the same distance apart, even if I get a different measurement later with a different yardstick with a different calibration. And, contrary to what Berkeley might say, they will still be there, 100 yards apart, all night long, even if I go to bed and don't see them.
Now suppose I am accelerated and all the "lengths" in my frame of reference contract, including my yardsticks and the distance between the goalposts. Now I will still measure them to be 100 yards apart, and nothing "appears" to be changed, so has it?
Yes, it has, which we've already stated by stipulating that everything contracted. The goalposts have "moved" (not only through space at an accelerated rate, but also closer together by virtue of the length contraction). The goalposts are no longer 100 yards apart, even though I still measure them to be that.
How about things outside my frame of reference, like, say, 2 stars which were one lightyear apart before I was accelerated. Are *they* still the same distance apart? Yeah, because that distance hasn't contracted, just lengths in my frame of reference. Even if I now measure them, with my shortened yardstick, to be more than 1 lightyear apart, they won't be any closer together or farther apart than they were yesterday. That distance has remained unvaried, whether it's "really" two lightyears, one lightyear, or any other distance (assuming that they two have not been accelerated).
How do I *know* which lengths have changed, and which haven't? By trusting in the Lorentz transformations, that's how. If SR is wrong, then I am too.
Preface: I just responded to your first question, but it is not currently being displayed.
One Brow said: "The answer to your question is no, as long as the players only look at what is in the plane."
OK, thanks. Would your answer be any different if they were playing "catch" with light beams? Like one guy would turn on a flashlight pointed at the other, then vice versa? Would the speed of light going toward the front of the plane vary from it's speed going toward the rear?
Let's say you have an accordian you want to play. You start with it all stretched out, arms' lengths about (say 5 feet). Then you push on both ends to make some noise, and your two hands end up only 2 feet apart. Has the distance (space) between the two ends changed? Yeah, it was 5 feet, now it's 2 feet. So, did the "space" between them "contract." No, not literally. The two ends MOVED closer to each other, with the result that there is now less distance separating them, that's all. The "space" between them did not contract while the two ends remained motionless. And, no, it's not the "same thing, either way."
The Lorentz transformations are designed to explain why a moving observers will still "see" (measure) light to be moving at the same speed as it was prior to his acceleration, even though it really isn't. Isn't this obvious? They are designed to explain why the observer is deluded, NOT why the speed of light is "really" constant (which it aint). If it was "really" constant, no tranformations would be needed.
Let's go back to my example: An object approachs us at the speed of 350 million miles per hour. When it is exactly even with us, we flash a light beam in the direction it is travelling. One hour later we measure the light beam to be 700 million miles from us, and the object to be 350 million miles from us. So, we see the light to be "outrunning" him at the rate of only 350 millions miles per hour, not 700 million.
Why doesn't he see it the same way? BECAUSE, per SR, he is being deceived by distorted measuring devices. But for the distortion he too would "see" (know) that the light is receding from him at the rate of only 350 million miles per hour, NOT 700 million, which is what he might believe if he mistakenly relied on miscalibrated measuring instruments.
The thing to keep in mind here is that SR tells us that his lengths "really" have shrunk, and that his clocks have "really" slowed down. That's why he falsely measures the light to be receding from him at the rate of c, when it really isn't.
The typical relativist wants to deny that there is a "real" change in the traveller's measuring instruments, EVEN THOUGH SR says there is. If he wants to maintin that there is no "real" change, OK, but it that case he must REJECT SR rather than insist it is correct.
How do they "deny" that it is real? Well, by claiming, for example, that the measuring instruments of the traveller are "just as valid" as are the non-traveller. But they aint "just as valid," at least not if SR is correct.
SR, just like Gailileo's RP, is designed to reveal why certain appearances are FALSE and do not properly represent "reality."
We see that they are not in the exact same place.
So, distance is real, measuring it is an abstraction. Would you say the distance between two objects is the amount you would travel on the smallest path between them? That if you take a different path through space, you can travel a different distance to get to that point, even though it does not change the actual distance (the length of a minimal path)?
I presume that similarly, time is real, measuring it is an abstraction. Now, does time share that latter property? Not as a mathematical model, not as an abstraction, not as a measurment, but as a reality. Do you acknowledge it could be possible to alter your movement through time, much as you alter your movement in space, even if not to the same degree? No wrong answer, btw, just different ways to interpret the results of experiements.
OK, thanks. Would your answer be any different if they were playing "catch" with light beams? Like one guy would turn on a flashlight pointed at the other, then vice versa? Would the speed of light going toward the front of the plane vary from it's speed going toward the rear?
No, it would not.
The two ends MOVED closer to each other, with the result that there is now less distance separating them, that's all. The "space" between them did not contract while the two ends remained motionless. And, no, it's not the "same thing, either way."
I agree.
Edit: This reallly isn't accurate: "SR, just like Gailileo's RP, is designed to reveal why certain appearances are FALSE and do not properly represent "reality."
I probably should have said: SR, just like Gailileo's RP, SERVES [not "is designed"] to reveal why certain appearances are FALSE and do not properly represent "reality."
Einstein did not "design" SR with that purpose in mind, and in fact originally believed (and tried to claim) that the perspectives of each observer were in fact "equally valid." Only later did he come to understand the true function of SR, which was to deny, not AFFIRM, false appearances.
Once this became apparent, Mach and the relationists rejected SR, as they had to do to remain consistent with their philosophy. Al came to realize that SR was NOT the relationalist theory he desired and intended it to be. He held out hope, however, that he could make GR fully relational, and thereby achieve his goals with GR, even though he failed to do so with SR.
One Brow said: "So, distance is real, measuring it is an abstraction."
No, that's not what I'm trying to say. The "separation" between two objects is "real." We use the abstraction of "space" to help mentally conceptualize and verbally explain this reality.
Measuring the (abstract) distance is not itself an "abstraction" even though the "thing" we are measuring is an absract concept. The act of measurement is a concrete, "real" activity taking place in space and time. The results we obtain from the act of measuring also make use of some abstract conceptualization, but the act of measuring, itself, is not abstraction.
The concept of a "yard," for example, is also an abstraction. A yardstick is not a "yard," per se, but it exemplifies or instantiates what our mental construct of a "yard" represents.
Measuring the (abstract) distance is not itself an "abstraction" even though the "thing" we are measuring is an abstract concept.
Even better. The distance is real, the measurement is real, the abstraction is matching it to some mental standard we might call a yard. So, similarly, time periods are real, the measurement is real, the abstraction is matching to something we think of as a second?
Looking forward to answers to the other questions, as well.
I said: "The concept of a "yard," for example, is also an abstraction. A yardstick is not a "yard," per se, but it exemplifies or instantiates what our mental construct of a "yard" represents."
One more elaboration, which I think is implied but perhaps not explicit. A "yard" is an abstract, idealized concept, not a "thing." If a yardstick expands or contracts, due to temperature changes, for example, it may no longer "correspond" to our concept of a yard in the same way it did before. The exemplification/instantiation of our concept is now even less perfect (it was never absolutely perfect to begin with).
Even so, our "concept" of a yard remains totally unfazed and unaltered. Again, the yardstick is not a yard, per se.
A logical positivist might want to claim that a yardstick is a yard, and nothing else is, or could be, a yard. But, of course, he would be wrong.
The post I am responding to appeared on my screen only after I made my last post prior to this (which may also help explain what I'm trying to say).
One Brow said: "The distance is real, the measurement is real, the abstraction is matching it to some mental standard we might call a yard."
We still don't seem to be on the same page. Your summary here seems to make a constrast between what is "real" and what is "abstract." This is a dichotomy which I do not adhere to. To me, the difference between something which is concrete and physically tangible and something like a concept, which isn't, is NOT that one is "real" and the other isn't "real."
They both have a degree of "reality" to them, as I see it, it's just a different "form" of reality.
One Brow said: "So, similarly, time periods are real, the measurement is real, the abstraction is matching to something we think of as a second?"
Well, yeah, "time periods" are real, if by "time period" you mean a "duration" or difference (separation in "time"). Time itself is still an abstraction.
The sun, for example, does not appear to us to rise and set at the exact same time. There is an intervening "duration" during which it appears to cross the entire visible sky before setting. This duration is "real." Even though "duration" is itself an abstract concept, it has a correspondence in the physical world which we can perceive and distinguish.
Everything which we can capable of speaking about involves some conceptualization, so it is AlWAYS at least of part of anything we discuss, even if we are discussing physically extended "things." "Rock" is an asbstact concept, for example, even if we are talking about a specific, concrete example, like the rock of Gilbraltar.
I have stated my opinion that "space" and "time" are NOT phsyically extended, tangible "things," but rather conceptual notions that do not partake of the kind of existence. Problems which might arise in measuring time and space are different questions. The answers one might give to such questions would NOT, in any way, change the conceptual nature of time and space as I see it, however.
I said: "Problems which might arise in measuring time and space are different questions. The answers one might give to such questions would NOT, in any way, change the conceptual nature of time and space as I see it, however."
So, for me, it follows that any "answer" to any question (whatever it is) that presupposes space or time to be physical objects or things with a concrete, tangible, spatially-extended existence is, ipso facto, necessarily a "wrong" answer. A category error, ya might say.
Do you care to comment on this claim of mine, Eric?:
"SR, just like Gailileo's RP, serves to reveal why certain appearances are FALSE and do not properly represent "reality....the true function of SR, [is] to deny, not AFFIRM, false appearances."
Actually, more accurate is the claim that certain "interpretations" of the appearances are false, not the appearances themselves, which cannot themselves be "false" in an objective sense. It may well be true that the earth does not "appear" to move and/or that the sun does "appear" to travel across the sky in and east-to-west direction everyday.
The "appearances" are what they are. They are not be "false" in the sense that they are not "real." The interpretation of those appearances can be false, though.
I said: "The "appearances" are what they are. They are not be "false" in the sense that they are not "real." The interpretation of those appearances can be false, though."
The failure to adequately distinguish between (1) appearances and (2) the proper interpretation of those appearances can cause definite conceptual problems.
An example comes to mind: An archeologist came across the skull of a dog-like animal which had a particular bone that was reminiscient of a bone found it whales. After documenting this fact, a PBS special then said "What is beyond dispute is that the descendants of this creature became whales," or words to that effect.
You seemed to whole-heartedly ratify the indubitability of this conclusion (interpretation). I could only laugh that any one would actually make such an extravagant claim, based on such minute and ambiguous "evidence." No one denies the appearance of an ancient animal skull. THAT is not in question. But.....
A logical positivist might want to claim that a yardstick is a yard, and nothing else is, or could be, a yard.
Did you know that at one time a meter was defined to be the length of a specific meter stick? Was that logical positivism?
We still don't seem to be on the same page. Your summary here seems to make a constrast between what is "real" and what is "abstract." This is a dichotomy which I do not adhere to. To me, the difference between something which is concrete and physically tangible and something like a concept, which isn't, is NOT that one is "real" and the other isn't "real."
Funny, you've awfully insistent that the slope of a graph has no relationship (as opposed to the mere lack of a causal relationship) the flight of some bees, even though one is an abstraction of the dance of a bee and the other is a reaction to that dance. If two real events have the same cause in part, how can they be said to have no relationship?
The sun, for example, does not appear to us to rise and set at the exact same time. There is an intervening "duration" during which it appears to cross the entire visible sky before setting. This duration is "real." Even though "duration" is itself an abstract concept, it has a correspondence in the physical world which we can perceive and distinguish.
Distance is real, but duration refers to an abstract concept with a real correspondence? OK. Can you pick a word you like to refer the real thing that a duration corresponds to? I'm good with time-period, if you have nothing better.
"Rock" is an asbstact concept, for example, even if we are talking about a specific, concrete example, like the rock of Gilbraltar.
Now we seem to be descending into a brain-in-a-jar conversation. I have no interest in that.
The answers one might give to such questions would NOT, in any way, change the conceptual nature of time and space as I see it, however.
However, you don't see them as being purely conceptual, in that you acknowledge there is some real thing that is "distance", possible some real thing that refers to two objects being in different directions relative to a thrid object, and that even a path you take moving from one object to another object is a real thing. I'm trying to see how many of these concepts you think apply to the reality of time-periods.
So, for me, it follows that any "answer" to any question (whatever it is) that presupposes space or time to be physical objects or things with a concrete, tangible, spatially-extended existence is, ipso facto, necessarily a "wrong" answer. A category error, ya might say.
Yes, I understand.
Do you care to comment on this claim of mine, Eric?:
"SR, just like Gailileo's RP, serves to reveal why certain appearances are FALSE and do not properly represent "reality....the true function of SR, [is] to deny, not AFFIRM, false appearances."
I think that is a reasonable philosophical take on SR, which can be consistent with certain beliefs of the nature of the universe (beliefs you seem reluctant to express directly, your preference seems to be to emphasize what you don't accept repeatedly). I don't think it's the only or exclusively accurate take on SR. One of the things I'm trying to valuate is if you might look as SR as a description of perspectives/optical illusions.
One Brow said: "One of the things I'm trying to valuate is if you might look as SR as a description of perspectives/optical illusions."
Well, I think it definitely IS a description of perspectives in many ways. The "optical illusion" part I'm not sure about. On the face of it, changing meters sticks and clocks are NOT merely the product of an optical illusion. Such phenomena are presented as "real," not just illusory, within the framework of SR itself. Like, if a clock stopped when reading 5:00, it would not be an "illusion" that the clock really reads 5:00. 5:00 would be the wrong time (if you want to call that "illusory"). Myself, I would say that the "appearance" given by the clock reading 5:00 is simply misleading or inaccurate, not "illusory."
Now, is there "really" a perceived length contraction? I don't know. Many deny this on theoretical grounds, and it has not been experimentally confirmed that I know of (I say that after reading the website you cited saying the contraction was "real"). Some say the imputation of a length contraction is merely a reference to an "illusory" effect caused by time dilation.
Experiments (and experince, such as with GPS) do seem to have confirmed that time actually changes with speed, as predicted by SR, however, so I take that part as a "real," non-illusory effect
One Brow said: "Funny, you've awfully insistent that the slope of a graph has no relationship (as opposed to the mere lack of a causal relationship) the flight of some bees, even though one is an abstraction of the dance of a bee and the other is a reaction to that dance. If two real events have the same cause in part, how can they be said to have no relationship?"
You seem to have either misread or forgotten what I said about graphs and bees. I can understand how a graph can "represent" or "model" the actual movements of bees. But, you're right, I would never take some exposition about lines on graph paper, no matter how long-winded, erudite, and scholarly, to be an acceptable explanation of the "cause" of the behavior being modelled.
One Brow said: "Distance is real, but duration refers to an abstract concept with a real correspondence? OK. Can you pick a word you like to refer the real thing that a duration corresponds to? I'm good with time-period, if you have nothing better."
With respect to your first sentence, again, no, I don't share the assumption or contrast you seem to be making. "Distance" and "duration" are both abstract concepts, and they are both "real" in some sense, even if they do not have a physical existence.
"Time-duration" is fine, but I might prefer "instant," for this reason: Measuring, or "counting," time generally consists of compiling the numbers of "instances" of some event(s) that presumably recur with a regular frequency. Each such "instance" would be an "instant," in that sense. A virtually infinite number of events could be used as an "instant" for that purpose. Rotations of the earth, swings of a pendulum, orbits of an electron, whatever.
In each of those cases, the "instant" being counted is one that is empirically ascertained and countable (quantifiable). Or at least so we presume. Is each "instant" TRULY equal to the last? We can't know that for sure, but we assume so.
One Brow said: "I don't think it's the only or exclusively accurate take on SR."
Here are just a few examples of "interpretations" of SR that I encounter on a regular basis:
1. SR proved there is no ether
2. The relativity principle proves that all motion is relative
3. SR proves that absolute time and absolute space do not exist
4. SR proves that all inertial frames are "equally valid."
I could go on, but I can't see any of these claims as just another alternative, reasonable philosophical interpretation of SR. Do you?
They are wrong, and some of them are wrong by the very terms of SR itself. As I said, you're welcome to take the philsophical position that "all reference frames are equally valid" if you want, but DON"T then try to also claim that SR is "valid." Only one of those two claims can be true, not both.
Take the twin example, once again. Both twins "see" the other's clock as running slow (IF, and only if, they each assume that they are at rest, and the other is moving, i.e., has been previously accelerated relative to the other). But both are not, and can not be, simultanously at rest, and SR acknowledges, in fact presupposes, this. Insofar as the travelling twin undertake to presume that he is at rest, he is WRONG and his assumption that his clocks have not slowed down, but his twin's clocks have. That view is INVALID, hence not "equally valid" with his twins view, which is valid as between the two.
One Brow said: "However, you don't see them as being purely conceptual, in that you acknowledge there is some real thing that is "distance"..."
Here again, you continue to equate "conceptual" with "unreal." We're simply not on the same page. You can make that equation, if you wish, but don't keep imputing it to me. I disagree with that suggestion
I said: "Rock" is an asbstact concept, for example, even if we are talking about a specific, concrete example, like the rock of Gilbraltar."
You responded: "Now we seem to be descending into a brain-in-a-jar conversation."
I have no clue where you think a brain-in-a-jar would come in. I'm simply elucidating the difference between an abstract concept and a concrete physical entity, as I see it. Nothing mystical or mysterious about it. I'm sure many, if not most, mainstream philosophers of epistemology, ontology, metaphysics, or whatever would agree in principle with this claim.
There are many individual stones, pepples, boulders, etc. in the world, often of quite distinctive composition, size, shape, etc. Although we "abstract" a few shared characteristics from all these things to form the "concept" of a rock, no one of them is "THE ROCK." There is no such (physically existent) thing as THE ROCK, which sets the standard for all other rocks. Rock is merely an abstract concept.
In general response to some of the other "questions" you seemed to be asking, let me say this:
Suppose my homey asks me, at the end of the day, what "path" I took that day. I would deem it to be a "complete" answer is I just said something like:
Well, first I went down 34th street to the liquor store. Then I went to the 7/11 on 27th and vine and robbed it. Then I went to the mall and blew some money. Then I went to the theatre down the road and watched a movie. Then I drove to Fayetteville to bang a ho. Then I came back here.
If he starts pressing me for the exact times at which all of these things occurred, I would be unable to tell him, exactly. And I would just say: "You asked me what path I took, and I done told ya. Don't go axxin what time, it aint got nuthin to do with my path, and I aint got a watch to begin with."
Would knowing the time make my whole narration more "precise?" Yeah, I spoze. Would it change the "path" I took? Not the way I see it, no.
As far as how we define the "distance" between two points, that often depends on the context. As strictly theoretical matter, yeah, we often say it is the most direct path. For two points on a plane, this would be a straight line. On a globe it would also be a straight line going right through a portion of the earth, if the globe in question is the earth. I could also say it is the distance entailed by traversing a great circle. If someone asked me "the distance" from St. Louis to Bejing, China, I could answer in more than one way.
But, as a practical matter, we often take practicalites into consideration when stating the "standard" distance. The "distance" between two towns is often stated as the distance travelled along a well established road, which may be longer than the distance measured "as the crow flies."
If I have some idiosyncratic way of routinely going from A to B (what I consider to be the "scenic route, or the route where I am most likely to come across an unattended bicycyle I can steal, for example), then, for me, the distance is the length of that particular route, however meandering.
All a matter of convention, really. There is no one, immutable way in which to express the distance between two points, that I am aware of.
On the other hand, if someone asked me how far it is from town A to town B along interstate 55, I would not say: Well, that depends entirely on your means of transporation. It's one distance if you walk, another distance if you ride a bike, another distance if you drive a raggedy-ass Ford with 4th gear missing, and yet another distance if you're driving a Ferrari full-throttle.
That would simply be a case of confusing distance travelled with time travelled.
One Brow asked: "Did you know that at one time a meter was defined to be the length of a specific meter stick? Was that logical positivism?"
Yeah, I knew that, if we're thinking of the same thing. I believe the definition was a little more detailed, and was limited to the length of this "standard" meter at a certain temperature, at a certain height above sea level, and a certain barometeric pressure, etc. It was also presumed to represent a certain portion of the earth's diameter (like, say, 1/100,000th) at noon on April first in some equatorial seaport when the tides were neutral, or something like that. As I recall, it was kept in a glass case in Paris.
This is an "operational definition," which logical positivists love. Operational definitions are fine, and often very desirable in scientific theories, but they do not automatically resolve all of the numerous issues which can arise when one tries to precisely specify an exact length which a "meter" supposedly has. The same is true with respect to any other particular abstract concept.
As suspect or unwieldy as that defintion of a meter was, it was far superior to the current one, for reasons I have stated more than once.
By the way, you gave the same answers to the playing catch on a plane that I would be inclined to give. That said, it those answers are correct, other questions arise. For example:
1. Why, given those premises, would anyone expect the Michelson-Morley experiment to "detect" absolute motion to begin with? If objects, including light, carry with them the inertia of their source, then the expectation would be that you can't detect the earth's motion, it seems.
2. Given the oft-confirmed Sagnac effect, these answers would seem incorrect. Experiments have shown that the speed of light travels at a different rate of speed, as measured by an observer in the earth's frame of reference, when it is going east (against the earth's rotation) that when it is going west. The explanation is presumably that the distance to remote locations on earth effectively increases or decreases while the light is "in transit," effectively rendering "stationary" points to the west closer, and points to the east farther away. The "correction" for this is strictly Galilean.
Why wouldn't the same hold true on an airplane?
I should have said that light "appears" to travel at a different rate of speed. If you consider the distance to San Francisco from New York and the distance to New York to San Francisco to be "equal," then you get a varying rate of speed because light takes longer to go one way than the other. If the distances are not the same, then not necessarily. Either way, it seems to contradict the oft-heard claim that the speed of light is completely independent of the speed of either the emitter or the receiver. Although some say this is strictly seen in rotatioal motion, some recent experiments purport to show the same effect with linear motion in a straight line.
aintnuthin said...
Well, I think it definitely IS a description of perspectives in many ways. The "optical illusion" part I'm not sure about. On the face of it, changing meters sticks and clocks are NOT merely the product of an optical illusion.
On the other hand, if their not changing...
Myself, I would say that the "appearance" given by the clock reading 5:00 is simply misleading or inaccurate, not "illusory."
Nor woud I claim that.
Experiments (and experince, such as with GPS) do seem to have confirmed that time actually changes with speed, as predicted by SR, however, so I take that part as a "real," non-illusory effect
I thought your position was that the clocks slowed.
But, you're right, I would never take some exposition about lines on graph paper, no matter how long-winded, erudite, and scholarly, to be an acceptable explanation of the "cause" of the behavior being modelled.
I can see not being the cause, but not being an explanation of the cause? Would an investigator have to bring a bee along with him to every lecture to explain the cause? I chalk that up to poor wording, and will assume you meant the exposition was not a sufficient cause. I agree with that.
"Time-duration" is fine, but I might prefer "instant,"
I'll go with "instant" for now, although I think the connotations might prove troubling later.
Is each "instant" TRULY equal to the last? We can't know that for sure, but we assume so.
Science does presume isotropy, and can't really function without it.
1. SR proved there is no ether
2. The relativity principle proves that all motion is relative
3. SR proves that absolute time and absolute space do not exist
4. SR proves that all inertial frames are "equally valid."
I could go on, but I can't see any of these claims as just another alternative, reasonable philosophical interpretation of SR. Do you?
1, 2, and 3 are not valid. 4 is valid, except that you don't prove anything in science to begin with. Rather, "when using SR all inertial reference frames are valid".
Insofar as the travelling twin undertake to presume that he is at rest, he is WRONG and his assumption that his clocks have not slowed down, but his twin's clocks have.
I agree he is wrong, but this does not invalidate 4, since he is wrong about having been in an inertial frame.
Here again, you continue to equate "conceptual" with "unreal."
I did include the word "purely", first of all. We can debate whether purely conceptual have a reality another day, perhaps.
I have no clue where you think a brain-in-a-jar would come in.
I was referring to a conversaion that came down to demanding a sort of evidence that can not be supplied in principle, such as proof that a person is not a brain in a jar.
Suppose my homey asks me, at the end of the day, what "path" I took that day. I would deem it to be a "complete" answer is I just said something like:
See, now you're just playing with definitions. If your homey asked you for a schedule, that the various streets you took would be irrelevant. If he asked for an itinerary, both would be relevant. Further, you could describe a schedule as precisely using an accepted time marker (such as a watch) as you could describe a path using accepted location markers (names of places).
As far as how we define the "distance" between two points, that often depends on the context.
Could this also be true for instants? Again, not as a model, but as a physical reality.
1. Why, given those premises, would anyone expect the Michelson-Morley experiment to "detect" absolute motion to begin with? If objects, including light, carry with them the inertia of their source, then the expectation would be that you can't detect the earth's motion, it seems.
My understanding was that Michelson-Morley was a test to detect ether, not absolute motion. Supposedly, light travelling perpendicular to the ether (whose rest frame was presumed to be an absoute rest frame) would be out-of-phase with light traveling back-and-forth in the ether. I always understoon (and recall being taught) their result to mean that the ether could not be detected, not as a disproof of absolute motion.
Experiments have shown that the speed of light travels at a different rate of speed, as measured by an observer in the earth's frame of reference, when it is going east (against the earth's rotation) that when it is going west. The explanation is presumably that the distance to remote locations on earth effectively increases or decreases while the light is "in transit," effectively rendering "stationary" points to the west closer, and points to the east farther away. The "correction" for this is strictly Galilean.
Why wouldn't the same hold true on an airplane?
To which experiements do you refer? I found this:
http://vixra.org/pdf/1008.0035v1.pdf
Based on GPS timing, Marmet [13] observed that a light signal takes about 14 nanoseconds longer than the average time (where average time equals distance divided by c) traveling Eastward from San Francisco to New York while the signal takes about 14 nanoseconds less than the average time traveling Westward from New York to San Francisco. Kelly [14] also noted that time measurements using the GPS show that a light signal takes 207.4 nanoseconds longer to circumnavigate the Earth Eastward at the equator than the average time while a light signal takes 207.4 nanoseconds less in the Westward direction around the same path.
In the airplane, all the observers and the light beam are in an inertial frame. However, for light to get from New York to San Francisco, it has to change frames by being reflected at least once. I don't pretend to be enough of a physicist to examine all the consequences of that, but it's clear enough that if you change inertial frames you aren't likely to get the same conclusion as you do when you have inertial frames. My first impression would be that this is not proof of the inconstancy of light due to that change. However, my impression could be wrong. I'm not pretending to speak authoritatively.
Although some say this is strictly seen in rotational motion, some recent experiments purport to show the same effect with linear motion in a straight line.
http://prl.aps.org/abstract/PRL/v39/i17/p1051_1
Of course, that's 1977. To which experiements do you refer?
By the way, the comment counter is approching 600. As a reminder, the paginator counts comments differently, so for a while the last page of comments will appear to be blank.
One Brow said: "I agree he is wrong, but this does not invalidate 4, since he is wrong about having been in an inertial frame."
I'm not sure what you mean by this. I thought everyone agreed he was in an inertial frame (excluding the time during which he initially accelerated and turned around).
We've been through all this too many times already, I spoze, but this "answer" from a mathematician appears to me to incorporate and number of logical and physical fallacies. I can easily explain his claims as being the "result" of a philosophical view, but I can't see how, even if you take that view, the inherent fallacies become coherent and consistent, and certainly not if you assume that SR is correct.
http://www.askamathematician.com/?p=4696
Take just this part, for example:
As the train, with Bob sitting in the exact center, passes Alice they high-five each other. Suddenly, both ends of the train are struck by lightning. Alice knows this because, very soon after the lightning strikes, the light from them get to her. Being smart, she realizes that the strikes must have happened at the same time, because they happened equally far away from her, and the light took the same amount of time to get to her (see picture). Moreover, really milking her cleverness, she predicts that Bob will see the lightning bolt at the front of the train first, and the lightning bolt at the back of the train second (see picture, some more)....Alice’s reasoning is completely solid, and she’s right when she says that the lightning bolts happened at the same time...
...Using the same reasoning Alice did, [Bob] figures that the speed of light is fixed (whether or not you’re moving), and the distance from him to the front and back of the train is the same, so since he saw the front bolt before the back, it must have happened first. And he’s right. Moreover, he thinks that the reason that Alice saw both at the same time is that she’s moving to the left, away from the first bolt and toward the second (picture).
Can't you see the rampant equivocation and circular reasoning in this "explanation?" Ironically, this author prefaces his explanation with the comment that:
"I should note here that the language physicists use makes the situation sound subjective; “the observer sees…”, “the person experiences…”, etc. However, none of the effects (covered in a minute) are due to observer based effects, like the delay caused by the time it takes light to get from place to place. Everything here is literal and physically real."
"Everything" in his explanation is definitely NOT "literal and physically real." His explanation obviously relies heavily on subjective perception and a priori assumptions, but he thinks otherwise.
Note that the ground observer assumes that the train traveller will see the lightning beam striking the front of the train first. This is presumably because, from her perspective, he is moving toward that flash, and away from the one which strikes the rear of the train (the sagnac effect?).
Just to elaborate and repeat what I've aleady said many times:
One thing to keep in mind here is that only one of these two observers bought a train ticket, boarded a train, and experienced accelerating forces prior to achieving his current "state of rest." Knowing this, why would he assume that she is the one moving? ["he thinks that the reason that Alice saw both at the same time is that she’s moving to the left, away from the first bolt and toward the second"]?
The underlying presumption given in this "explanation" is clearly that observer motion toward or away from the source of emission WILL have an effect on how "soon" you see the light reach you. This is because the distance the light must travel to reach you changes as you move. But since both travellers assume, in this example, that the speed of light never varies, even if you are moving, they simply conclude that one emission "occurred first," and one second. Without that assumption, the train passenger would simply assume that the two strikes did indeed happen simultaneously, but that he did not see them simultaneously BECAUSE he is moving.
I'm not sure what you mean by this. I thought everyone agreed he was in an inertial frame (excluding the time during which he initially accelerated and turned around).
The knowledge that he is the one who accelerated more than his twin means that he has not been in an intertial frame. Why try to be all relativistic about it?
Note that the ground observer assumes that the train traveller will see the lightning beam striking the front of the train first.
It does have a shorter path.
Knowing this, why would he assume that she is the one moving?
Because this is a hypothetical to illustrate a point, not a serious examination of an actual phenomenon.
Without that assumption, the train passenger would simply assume that the two strikes did indeed happen simultaneously, but that he did not see them simultaneously BECAUSE he is moving.
When you see one bolt of lightning strike, followed very closely by a second, how often do you think to yourself they were really simultaneous, but you were moving?
When one claims that inertial frames are "equivalent" he is really simply claiming that, as a matter of mathematics, you can get the same numerical "results" regardless of which of two relatively moving frames you wish to treat as moving.
In the above example, the two light flashes will NOT reach both observers at the same time, regardless of which one you treat as "motionless." But, so what? What does that have to do with "equivalence" as a matter of physical "reality?" As we know, you will get the same result as to the time of the occurrence of the next solar eclipse whether you choose a geocentric or a heliocentric premise. Does this mean that it is physically true that the earth orbits the sun AND, at the same time, it is ALSO physically true that the sun orbits the earth?
One Brow said: "The knowledge that he is the one who accelerated more than his twin means that he has not been in an intertial frame. Why try to be all relativistic about it?"
Well, Eric, we've been through all this before. Einstien himself acknowledged, and particle accelator experments have shown, that acceleration, per se, has no effect whatsover on the passage of time that is over and above the normal prediction that, the faster you go, the more "time" (clocks, OK) shows down.
The change in the rate of time passage occurs WHILE he is in inertial motion, not before or after. Of course, even this is not mathematically true, I guess, given the non-sensical mathematical "time slippage" that guys like Van Flandern rightly ridicule on physical (but not mathematical) grounds.
The traveller has made a mistake, that's true. But his mistake in not that he is in an inertial state while travelling, because he is. It is the mistake that he makes when he assumes that he is "at rest" when he has in fact been previously accelerated relative to his twin and he knows it.
One Brow said: "When you see one bolt of lightning strike, followed very closely by a second, how often do you think to yourself they were really simultaneous, but you were moving?
Probably never, but that irrelevant to the point. What I "think" does not dictate what "is," that's the point. I agree that a blind man cannot, and does not, see a door in front of his face, but I do not therefore conclude that there is, and can be, no door in front of him.
If I was riding on a train, and if I saw two event on two different parts of the train as (non)"simultaneous," and if I wanted to think about it, then I would know that me travelling toward/away from the two events would have an effect on my perception.
One Brow said: "Because this is a hypothetical to illustrate a point, not a serious examination of an actual phenomenon."
OK, and what "point" is being illustrated? It can only be the point that moving toward or away from the source of an emission of light WILL affect the time it takes to reach you. Both the ground observer and the train passenger presuppose that fact.
I said: "Note that the ground observer assumes that the train traveller will see the lightning beam striking the front of the train first.
You responded: "It does have a shorter path."
OK, then you agree with the point. The "length" of a standard meter does not shrink with motion, it's simply that light must travel farther in terms of "standard" meters. Knowing this, the passenger would not properly conclude that the lightning actually struck the front of the train first. He would, of course, still know he "saw" it first, but he would also know why. That's because it travelled less distance to reach him, NOT because light travels at a constant speed, regardless of his motion and that therefore the flash at the front of the plane "REALLY" did strike first. The "appearance" of it having struck first would be only that, an appearance. That appearance would be a distorted one caused by his motion and not an accurate refection of the actual circumstances.
... that acceleration, per se, has no effect whatsover on the passage of time ...
I don't recall saying the acceleration did anything. We were discussing how the twins would know which clock movement had really changed.
OK, and what "point" is being illustrated?
Thet your notion of whether events are simultaneous or not can be dependent on what you choose for a rest frame. I agree that in the story around the analogy, one choice is more natural. But that's not always the case.
YOu didn't answer this:
As far as how we define the "distance" between two points, that often depends on the context.
Could this also be true for instants? Again, not as a model, but as a physical reality.
One Brow said:
YOu didn't answer this:
As far as how we define the "distance" between two points, that often depends on the context.
Could this also be true for instants? Again, not as a model, but as a physical reality.
I guess I didn't answer that particular question because I don't understand what you are asking.
I will just say this. We might choose to "define" the distance to the nearest town either "as the crow flies" or as measured along meandering route 66. Either way the distance "as the crow flies" would remain the same and the distance "along 66" would likewise remain the same. The two "distances" would be different from each other, but unvarying with respect to themselves. How we chose to define the distance from A to B, would in NO WAY affect our definition of a mile or of a yard.
Let's say two guys throw a ball toward me at the same time but they don't reach me at the same time. What am I to conclude from this?
Well, it could be a number of things. Maybe they're the same distance away, but simply not throwing the ball at the same speed. On the other hand, maybe they're both throwing the ball at the same speed, but one is farther away. And, of course, it could be any combination of things. Maybe (1) they're not the same distance from me AND (2) they're not throwing the ball at the same speed either.
IF I assume, as a matter of immutable fact, that they ARE the same distance from me, then I MUST conclude that they are NOT throwing the ball at the same speed.
On the other hand, if I assume, as a matter of immutable fact, that they ARE throwing the ball at the same speed, then I MUST conclude that they are not throwing the ball to me from the same distance.
My assumptions therefore dictate my conclusions.
Now, let's look at the guy on the train. He concludes that the light at the front of the train "really" did strike first BECAUSE, as the author implies, he assumes he is not moving. His assumption is that, had they really struck "at the same time" THEN he would have seen them at the same time? Why? Because again, as the author indirectly says, he assumes that they have to travel the same distance to reach him (because he is at the midpoint of the train).
But the author also clearly implies that the light DOES not have to travel the same distance to reach him, and you agree with this. Therefore that assumption is, by the author's own premises, WRONG. Wrong assumptions generate wrong conclusions. The guy can only conclude that the light hit the front first IF he assumes that both must travel the same distance to reach him.
I assume you agree, but I could be making a wrong assumption here. Do you agree?
I said: "But the author also clearly implies that the light DOES not have to travel the same distance to reach him, and you agree with this. Therefore that assumption is, by the author's own premises, WRONG. Wrong assumptions generate wrong conclusions. The guy can only conclude that the light hit the front first IF he assumes that both must travel the same distance to reach him."
I misstated this, and/or stated it in a misleading way. Let me backtrack...
The guy on the train "sees" the light from the front of the train first, and therefore assumes it actually happened first. His reasoning is this:
(1) The two beams are equidistant from me.
(2) They are travelling at the same speed, yet
(3) They did not reach me at the same time,
Therefore, the one I saw first had to have happened first.
The equivalent conclusion in my two guys throwing balls example would be: The two guys did not throw the ball at the same time, despite the fact that I thought they did, that's all.
Either way premise number (1) is mistaken, once the effects of motion are considered, or at least so this author assumes ab initio.
Speed is comprised of two components, time and distance and all three concepts (speed, time, and distance) are therefore interrelated.
I can assume that both speed and distance are absolute, and still get the same answer, if I alter time.
I can assume that both speed and time are absolute, and still get the same answer, if I want to alter distance.
Or, of course, I can assume that time and distance are absolute, but in that case I will not always get the same speed. The "actual" speed will be dictated by the actual time elapsed and the actual distance travelled, not predetermined, a priori.
Of course, this (latter) is as it should be, since speed is computed reference to time and distance. Distance is not defined by speed.
I should have added "nor is time" to my last post.
One Brow said: "Thet your notion of whether events are simultaneous or not can be dependent on what you choose for a rest frame. I agree that in the story around the analogy, one choice is more natural. But that's not always the case."
Well, that's true, but that's not my real point, which is basically that...
1. My "notion" about how things occur is not what physics seeks to establish
2. What I happen to "choose' for a reference frame says nothing about which rest frame might be "actual" (think geocentricism vs heliocentricism)
3. The mere fact that no "natural choice" may be readily apparent to me also says nothing about what "choice" accurately reflects nature.
4. And, of course, the simple assumption that even if you have two (or more) options from which you can choose, then regardless of which one you do choose, they can't BOTH be the "right" choice if they are mutually exclusive and contradictory.
The basic reasoning and conclusions of the relationalists is as follows:
1. Both the passenger and the stationary observer can view the other as moving and themselves as at rest.
2. Therefore, it is impossible to conclude that either one is "really" moving.
3. Therefore the notion that something is 'really moving" is metaphysical, fictitious, and meaningless.
There are many logical absurdities that result from such premises (and the tacit assumptions they contain), but, even if one had no objection to them on those grounds, they are strictly "philosophical" views which have nothing to do with physics. Or, put another way, the whole discipline of "physics" is just a hollow, empty, fictitious, and meaningless form of metaphysics given those premises.
A collateral observation, which may or may not be pertinent to your questions about distances, etc.
Let's say, just for the hell of it, that Mars follows a seemingly circular, but actually "straight" geodesic path around the Sun. It follows this path only because space is curved, and, for this reason, curved space "forces" it to follow that path.
Now, then, at any given moment, how far is Mars from us, and how would we define it? Well, I can tell you what we wouldn't normally do.
We wouldn't measure the length of it's orbit around the sun, and we wouldn't assume that would be the shortest path by which we could reach it, curved space, or not.
We would assume that we could head right for it, in a straight euclidean line, and reach it most directly and in the most timely fashion, by doing that. We would just follow the same path that we assume that a light beam which we bounce off of it follows.
Why don't we conclude that the light beam can never reach it because the "curvature" of space would make it impossible for the light beam to go straight for it? Would we have to direct our light beam toward some point in the orbit of mars, perhaps in the opposite direction from where we currently see Mars to get there? That way light could reach a point where the same "curved space" which Mars is compelled to submit to would also force light to go toward Mars, eh?
We don't seem to think so. We seem to think we can just cut straight across "curved space" unaffected. As if, for example, we could just go directly from St. Louis to China by "cutting through" the earth.
One Brow said: "To which experiements do you refer? I found this:
http://vixra.org/pdf/1008.0035v1.pdf"
I was actually thinking of the 1971 Hafele-Keating experiment. Many strongly criticized this experiment when it was later revealed that they had, without disclosing it, manipulated and massaged the raw data before presenting their conclusions.
Some have argued that the actual data shows that Einstein's light postulate is invalid and that the experiment actually supports the "universal time postulate" which apparently holds that "in a coordinate system in which the source is in motion, the velocity of light is not a constant c but is c + v, where v is the instantaneous velocity of the source."
See, e.g., http://www.shaping.ru/congress/english/spenser1/spencer1.asp
A wiki article on the topic says the experiment has since been repeated with the same results. But the only point I was making here was that, even in the Keating experiment, adjustments were made for the Sagnac effect: "the atomic clocks in the westbound plane actually operated at a faster rate than the stationary clock due to kinematic effects, but that the eastbound plane operated at a slower rate than the stationary clock due to kinematic effects."
http://www.teslaphysics.com/Chapters/Chapter030-H-K.htm
The GPS system also corrects for the sagnac effect:
"The Sagnac effect has an important influence on the system. Since most GPS users are at rest or nearly so on earth's surface, it would be highly desirable to synchronize clocks in a rotating frame fixed to the earth (an Earth-Fixed, Earth-Centered Frame or ECEF Frame). However because the earth rotates, this is prevented by the Sagnac effect, which is large enough in the GPS to be significant...Thus the Sagnac effect forces a different choice for synchronization convention. Also, the path of a signal in the ECEF is not "straight." In the GPS, synchronization is performed in the ECI frame; this solves the problem of path-dependent inconsistencies."
http://www.leapsecond.com/history/Ashby-Relativity.htm
I said: "4. And, of course,... even if you have two (or more) options from which you can choose, then regardless of which one you do choose, they can't BOTH be the "right" choice if they are mutually exclusive and contradictory."
This author routinely and consistently ignores this logical "truth" when he says such things as: "Both Alice and Bob are completely correct."
As a physical matter, they cannot both be at rest and both be moving, all at the same time. Granted, they can each "assume" they are not moving, but both simply cannot be right.
The claim this guy makes to the contrary is obviously logically flawed for that reason alone, even apart from the illogic stemming from the implied assumption that, all at the same time, (1) moving toward/away from a light source will alter the time it takes to get to you because the distance is changing and (2) the distance the light must travel to reach you remains unchanged even if you are moving.
The just want to keep having it both ways, and has no inkling of how impossible his claims are. He even has the gall to claim that his explanation: "However, none of the effects (covered in a minute) are due to observer based effects, like the delay caused by the time it takes light to get from place to place. Everything here is literal and physically real."
The question he is asked is: "According to relativity, two moving observers always see the other moving through time slower. Doesn’t one have to be faster?"
His answer is "no." His answer is also wrong. By his own reasoning, and that of SR, the one which has been previously accelerated is faster.
Each observer can SEE the other's clock as running slower, but they cannot, as a matter of either physics or logic, both "really" run slower than the other. The either run the same, or else one is slower/faster than the other.
As long as there are people (and there are plenty) who continue to claim that "Both Alice and Bob are completely correct," there will continue to be arguments over the true meaning and implications of the resolution to the "twin paradox" (which debates keep raging after over 100 years).
One Brow said:
"Although some say this is strictly seen in rotational motion, some recent experiments purport to show the same effect with linear motion in a straight line.
http://prl.aps.org/abstract/PRL/v39/i17/p1051_1
Of course, that's 1977. To which experiements do you refer?"
The wiki article of the Sagnac effect says (among other things): "Recent experiments demonstrated that there is a travel-time difference Δt = 2vΔL / c2 between two counterpropagating light beams in a fiber segment of length ΔL moving at a speed v, whether the motion is uniformly translational or rotational in a loop."
http://en.wikipedia.org/wiki/Sagnac_effect
In "rebuttal" wiki also notes that: "Tartaglia and Ruggiero (in an arXiv preprint) argued that this effect is "due to the closeness of the path followed by light and to the relative motion of the observer with respect to the physical system obliging the beam to bend and come back to the observer" - and it is thus perfectly consistent with special relativity."
However, if you read the Tartaglia and Ruggeriero article, they clearly state that:
"Recently Wang, Zheng, Yao, and Langley[1] (WZYL) have verified by experiment an effect, which is indeed the Sagnac effect seen by a uniformly moving observer....If this is correct the Sagnac effect has nothing to do with rotations and accelerated motion, rather it is a peculiarity of relative motion relevant to the old debate about the one- or two-ways measurement of the speed of light."
http://arxiv.org/PS_cache/gr-qc/pdf/0401/0401005v1.pdf
In one of this expositions on SR, Einstein clearly postulates that the one-way speed of light is the same, regardless of direction. To his credit, he fully acknowledges that this is a totally unproven claim, and asserts that he is making it freely and voluntarily, without proof, in order to establish an operational definition of "simultaneity." I could probably find it, if I had to, but haven't looked for it again.
The following are excerpts from the Einstien passage I had in mind:
"We encounter the same difficulty with all physical statements in which the conception “simultaneous” plays a part. The concept does not exist for the physicist until he has the possibility of discovering whether or not it is fulfilled in an actual case. We thus require a definition of simultaneity such that this definition supplies us with the method by means of which, in the present case, he can decide by experiment whether or not both the lightning strokes occurred simultaneously....
By measuring along the rails, the connecting line AB should be measured up and an observer placed at the mid-point M of the distance AB. This observer should be supplied with an arrangement (e.g. two mirrors inclined at 90°) which allows him visually to observe both places A and B at the same time. If the observer perceives the two flashes of lightning at the same time, then they are simultaneous...
But an examination of this supposition would only be possible if we already had at our disposal the means of measuring time. It would thus appear as though we were moving here in a logical circle...I maintain my previous definition nevertheless, because in reality it assumes absolutely nothing about light. There is only one demand to be made of the definition of simultaneity, namely, that in every real case it must supply us with an empirical decision as to whether or not the conception that has to be defined is fulfilled...That light requires the same time to traverse the path A —> M as for the path B —> M is in reality neither a supposition nor a hypothesis about the physical nature of light, but a stipulation which I can make of my own freewill in order to arrive at a definition of simultaneity.”
http://www.bartleby.com/173/8.html
As I mentioned in my comment about the "meter stick," operational definitions are usual but they do NOT resolve underlying questions which can arise about their accuracy.
Edit: "As I mentioned in my comment about the "meter stick," operational definitions are USEFUL [not usual"] but they do NOT resolve underlying questions which can arise about their accuracy.
This "definition" later gets turned around, as evidenced by the excerpt from the physicist I quoted from a while back.
In effect he said, if you recall, that you know that two objects (mirrors) in different direction are equidistant from you if the light you direct to them simultaneously returns to you simultaneously. And, he claimed, that you could therefore correctly deduce that the light you sent hit them simultaneously, thereby establishing "distant simultaneity."
As I commented then, the circularity should be obvious. Now "equal distance" is being derived from the supposed constancy of the speed of light. If it were not "constant" (as suggested by the Sagnac effect) then the mirrors would NOT be equidistant from you.
As I have stated (an shown) recently, your assumptions DICTATE your conclusions. If you haven't proven your assumption, then you certainly haven't proven your conclusion, even if it necessarily follows from your conclusion. And, needless to say, it would be fallacious (affirming the consequent) to say that, if your conclusion turns out to be true, then that proves your premises are true.
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