Why in the world would Einstein suggest....

This thread is going on 40 pages, and I hope you'll understand if I don't want to read every page.

To briefly summarize what I've tried to discuss in this thread:

1. The "relative simultaneity" which was addressed in the first post just boils down to this: Any two relatively moving observers MUST make contradictory claims about who is moving. Without that required conflict, the theory completely falls apart. It is this very conflict (together with assumptions which are external to the theory) that creates all the paradoxes that plague SR.

2. Theories of motion which do not impose this artificial and very dubious requirement on observers make all the same predictions, just as well, as does SR. "Relative simultaneity" is by no means required to explain relative motion. SR cannot be said to be superior on the basis any experimental findings or other empirical grounds. SR is not a "proven fact."

3. In practice (e.g., the gps, astronomers, etc.) SR is not used for calculations. Instead a theory which incorporates the synchronization methods of an AST (absolute simultaneity theory) is used to calculate and to achieve practical results. These theories work just as well in non-inertial frames, where SR falls apart and must be rejected.

4. Einstein himself was never satisfied with the theory. By 1907 or so, he had rejected it. In general relativity, the speed of light is NOT claimed to be constant.

5. The premises of SR are, at bottom, metaphysical claims.

6. I have seen no one in this thread meaningfully deny or debate these claims, notwithstanding the seeming consensus that SR is superior to any alternate theory.

In Section 11.2, we introduced the two postulates of special relativity, namely the speed-of-light postulate and the relativity postulate....It's interesting to see what happens if we relax these postulates....it's easy to imagine a universe where the speed of light depends on the reference frame. Light could behave like a baseball, for example. (Page XI-38)

[First Postulate:] The speed of light has the same value in any inertial frame. I don't claim that this statement is obvious, or even believable...This is a rather bizarre statement. It doesn't hold for everyday objects...The truth of the speed-of-light postulate cannot be demonstrated from first principles. There is one more postulate in the Special Relativity theory, namely the "Relativity" postulate (also called the Principle of Relativity). It is much more believable than the speed-of-light postulate...(Page XI-8)

It is remarkable that we were able to prove so much by using only the relativity postulate....Any difference in the numerical value of V can be absorbed into the definitions of the unit sizes for x and t. Given that V is finite, it has to be something, so it doesn't make sense to put much importance on its numerical value. There is therefore only one decision to be made when constructing the spacetime structure of an (empty) universe. (Page XI-40)

...nearly all of special relativity can be derived by invoking only the second postulate. The first postulate simply fills in the last bit of necessary info by stating that something has the same finite speed in every frame. It's actually not important that this thing happens to be light. It could be mashed potatoes or something else...it's sufficient to state the first postulate as, "There is something that has the same speed in any inertial frame." (Page XI-9)

Experimental Basis for Special Relativity in the Photon Sector
Daniel Y. Gezari
NASA/Goddard Space Flight Center, ExoPlanets and Stellar Astrophysics Laboratory,
Code 667, Greenbelt, MD 20771
and
American Museum of Natural History, Astrophysics Dept., New York, NY 10024

One of the most reassuring things we know about modern physics is that the special theoryof relativity has faced a century of experimental challenges, and passed every test. This prompts the question, what has been tested and what has not?

The three new matter effects are time dilation, mass increase and E = mc2. The five new photon effects are:

invariance of the speed of light (c) to motion of the observer
Lorentz-FitzGerald length contraction
relativistic Doppler effect
relativistic stellar aberration
relativistic source brightening

Surprisingly, none of the five new optical effects assumed or predicted by special relativity have ever been observed to occur in nature or demonstrated in the laboratory...The local Lorentz invariance of c can now only be inferred,... but there are serious difficulties with this view: Observations of moving sources cannot discriminate between special relativity and the classical ether hypothesis (Section 2.1), the equivalence of source and observer motions has not been established experimentally (Section 2.1), [and] the well-known ether drift experiments (e.g., Michelson and Morley 1887) have recently come into question (Section 3.3)

By the time modern instrumentation became available in the 1960’s special relativity had already become part of the fabric of quantum mechanics and modern particle physics. A definitive historical study by Brush (1999) suggests that the early acceptance of special relativity was based more on its mathematical beauty than on the strength of the available experimental evidence, and the fact that it had been embraced by a few influential physicists (e.g. , Planck; Pauli 1921).

One of the most familiar arguments for the validity of special relativity is that the Global Positioning System (GPS) navigation system would not achieve high accuracy without making special relativistic corrections....But the Sagnac effect is a purely classical, first-order effect that has somehow been incorrectly re-classified in this application as a special relativistic effect...a first-order timing correction must be made for the accurate performance of the GPS system, just the amount attributable to the velocity component of the satellite constellation along the line-of-sight in the ECEF frame. The fact that this first-order timing correction is required at all is in direct conflict with special relativity.

At least one of the five relativistic optical effects predicted by the special theory of relativity should be confirmed by direct observation; the most significant of these would be the invariance of c to motion of the observer. To this end we have made a two-way lunar laser ranging measurement of the speed of light with a moving detector (Gezari 2009) and we are pursuing one-way laser ranging observations outside the Earth’s atmosphere (Gezari et al. 2010) as well as ultra-fast pulse timing measurements in the laboratory (Gezari et al. 2010).

The speed of laser light pulses launched from Earth and returned by a retro-reflector on the Moon was calculated from precision round-trip time-of-flight measurements and modeled distances. The measured speed of light (c) in the moving observers rest frame was found to exceed the canonical value c = 299,792,458 m/s by 200+/-10 m/s, just the speed of the observatory along the line-of-sight due to the rotation of the Earth during the measurements. This is a first-order violation of local Lorentz invariance; the speed of light seems to depend on the motion of the observer after all, as in classical wave theory, and implies that a preferred reference frame exists for the propagation of light.

...
To briefly summarize what I've tried to discuss in this thread:

1. The "relative simultaneity" which was addressed in the first post just boils down to this: Any two relatively moving observers MUST make contradictory claims about who is moving. Without that required conflict, the theory completely falls apart. It is this very conflict (together with assumptions which are external to the theory) that creates all the paradoxes that plague SR.
...

that a man on a moving train does NOT know he is moving relative to the earth's surface, and not vice versa? Who in the world would get on a train, feel himself being accelerated, and then, once a uniform speed has been attained, conclude that the trees, stop signs, houses, etc. are moving past him while he remains completely motionless. Isn't this rather absurd?

Who would ask the conductor if Chicago stops here?

Yet this presumption is the sine qua non of special relativity theory, isn't it?

I think the point is not so much that the mover must make a claim or know/not know anything....I think the point is not so much that the mover must make a claim or know/not know anything.

Instead, what physical experiment could he perform (not resorting to commonsense, naive realism) to prove whether he was moving or the earth was? Speaking in pure physical terms, the effects are identical, as far as I know.

...But the point is accurate, even if metaphorical. As a matter of (adjusted) mathematics, SR requires that, again, metaphorically speaking, that "A sees B as moving and B sees A as moving." "Seeing" just means assuming, in this context.

Well, this, in part, is what Thomas and I were discussing. This proposition goes back to Gallileo, and many relativists cite him as saying "you can't determine who's moving."

Gallilo never said any such thing. In fact he said the opposite. What he DID say was that, in a closed, uniformly moving environment (a ship's cabin below deck), no physical experiment can tell you you're moving. Fair enough. But "physics" in not limited to what blind-folded observers chained to a wall can "determine."

Gallileo also said that, as soon as he went up on deck, the sailor would have a variety of information that would inform him that he was moving, even if he didn't couldn't "feel" it. He's the one, after all, who insisted that the earth was "really' moving around the sun.

It is correct to say that physical experiments in a closed environment won't tell you if you're moving (if the motion in uniform). It is totally incorrect to say that therefore "physics" tells you that you can't know you're moving, as (some) relativists want to claim.

3. I am using "moving" here in a strictly relative, not absolute, sense. What, as between the sailor and the shore, is moving? What, as between the sun and the earth, is revolving around what?

It true that both the earth and the sun are also (jointly) moving toward the constellation Leo at the rate of about a million miles an hour, but the question if NOT about their absolute motion. It's just a question involving one versus the other.

And that brings up another confusion induced by relativists--the vague suggestion that if you don't have an ABSOLUTE frame of reference, then nothing can be said about motion. But, of course, they have plenty to say about relative motion (not all of it credible).

That is missing a necessary caveat: "You can't know whether or not you're moving given only the data at hand" seems accurate.

I'm not sure that the physics would be affected if the movers were scientifically literate people who were able to take stock of the situation and conclude, "I can't tell whether it's me moving or the other guy or both of us."

Well, spherical cows exist for a reason, and I don't think that reason is to disingenuously skew results of experiments. Artificially limiting parameters is necessary to select for ones that help you specifically and unambiguously answer the question you're investigating.

I'm not aware of anyone who says that the lack of an absolute frame means nothing can be said about motion

Quote:

I'm not sure that the physics would be affected if the movers were scientifically literate people who were able to take stock of the situation and conclude, "I can't tell whether it's me moving or the other guy or both of us."

Well, physics would be, in many ways. Not long ago, in this thread, I posted a link to a paper by a Professor saying, just for example, that an AST would "tell" us something entirely different about the rate of universal expansion than SR would "tell" us.

Quote:

I'm not aware of anyone who says that the lack of an absolute frame means nothing can be said about motion

Well, "nothing" was hyperbole, of course. But, if I recall correctly, you were taking the position that, as between A and B, it couldn't even be known whether both "at rest" when they were relatively moving. To me, that's a "know-nothing" stance if I ever heard one.

SR tells us that there's no absolute frame of reference.

My understanding is that SR tells us that it doesn't matter whether you treat the situation as if the earth were moving or if the person were. You get the same answer. It's more like saying that it's a nonsense question. You can work the equations equally well by treating A as stationary and B moving or both moving. Since the answers will come out the same, it doesn't make any sense to choose either one as the one that's "really" moving.

I don't recall making any statement about not being able to know whether both were at rest. Seems to me that might be the only time you could be certain.