First historical experiment disproving Ritz emission theory?

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Discussion Overview

The discussion revolves around the historical context and experimental evidence related to Ritz's emission theory and its validity compared to special relativity (SR). Participants explore the timeline of experiments that may have disproven Ritz's theory, particularly focusing on early tests and the implications of extinction effects in light propagation.

Discussion Character

  • Debate/contested
  • Historical
  • Technical explanation

Main Points Raised

  • Some participants note that Ritz's theory proposed a speed of light dependent on the source's speed, contrasting with SR's constant speed of light.
  • There is mention of early tests, such as de Sitter's experiment in 1913, which some argue were problematic due to optical extinction.
  • Participants discuss the Sagnac effect and its implications for emission theories, suggesting it may provide evidence against Ritz's theory since it occurs in vacuum conditions.
  • Some express skepticism about the sufficiency of early experiments to conclusively rule out Ritz's theory, questioning whether any direct disproof existed before 1964.
  • Others assert that the Sagnac effect and De Sitter's double stars experiments were sufficient to rule out Ritz's original theory, despite the complexities introduced by extinction effects.
  • Questions arise about the existence of indirect evidence against Ritz's theory from a multitude of other experiments, with participants seeking clarification on what these might be.
  • There is a discussion about the Fizeau experiment, which some believe also contributed to rejecting ballistic emission theories.

Areas of Agreement / Disagreement

Participants do not reach a consensus on whether Ritz's theory was conclusively disproven before 1964, with some asserting early experiments were sufficient while others remain unconvinced. The discussion reflects multiple competing views on the interpretation of historical experiments and their implications for emission theories.

Contextual Notes

Participants highlight limitations in the historical understanding of extinction effects and the varying interpretations of experimental results over time. The discussion also notes the complexity introduced by different formulations of emission theories.

Who May Find This Useful

This discussion may be of interest to those studying the historical development of theories in physics, particularly in the context of special relativity and emission theories, as well as those exploring the implications of experimental evidence in theoretical physics.

bcrowell
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Ritz proposed in 1908 that SR was wrong, and that the speed of light would depend on the speed of the source according to Galilean addition of velocities, c+v. The review linked to from PF's sticky on the experimental basis of SR has a nice section on this: http://www.edu-observatory.org/physics-faq/Relativity/SR/experiments.html#moving-source_tests

These results are typically described in terms of a limit on k, where the speed of light is c+kv, k=0 being SR and k=1 being the Ritz theory.

Early tests such as de Sitter's in 1913 http://en.wikipedia.org/wiki/De_Sitter_double_star_experiment were later realized to be problematic because of optical extinction. The earliest test they list that disproves k=1 and is not subject to optical extinction or other issues is a pair of experiments in 1964.

It seems impossible to believe that the Ritz theory was really viable until 1964. Of course nobody believed it by then, and it was indirectly inconsistent with a gazillion other experiments, but was there really no direct disproof of k=1 until 1964? Were the early tests such as de Sitter's sufficient to falsify k=1, even given extinction? (De Sitter claimed k<.002, but he didn't consider extinction.) Historically, what was the first direct test that ruled out the Ritz theory?
 
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Good question. I don't think I've seen any particular experimental test acknowledged in the literature which definitely rules out the Ritz theory. As you mention, it's typically reasoned away on the basis of additive velocities, De Sitter's reasoning (which I find pretty unconvincing) and lack of compliance with the Oseen extinction theory (which I find even less convincing).

However, a full analysis of the Sagnac experiments (1913?) and all related ones including the Michelson-Miller experiment a couple of decades later very clearly shows that emission theories do not apply in the case where two light sources having different paths to the detector are compared. If the Ritz theory were correct no shift in phase of the 2 signals would occur, right?
 
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PhilDSP said:
Good question. I don't think I've seen any particular experimental test acknowledged in the literature which definitely rules out the Ritz theory.

No, please take a more careful look at what I wrote in #1, and read the edu-observatory.org link. It was definitely directly disproved by experiments in 1964. The only question is whether it was directly disproved before then.

PhilDSP said:
As you mention, it's typically reasoned away on the basis of additive velocities, De Sitter's reasoning (which I find pretty unconvincing) and lack of compliance with the Oseen extinction theory (which I find even less convincing).

No, that's not what I said.
 
bcrowell said:
Historically, what was the first direct test that ruled out the Ritz theory?

Ritz's original theory doesn't involve extinction effects, and therefore it was conclusively ruled out by DeSitter's double stars and the Sagnac effect, both in 1913.

As regards the modified "extinction emission theory" (which wasn't discussed before the 1960ies), they were also conclusively ruled out after 1964 by a lot of experiments in vacuum (Sagnac type or with moving sources) and Brecher's modified version of DeSitter's experiments.

However, if there were also relevant experiments before 1964 which were overlooked by Fox, I don't know.

* Fox, J. G. (1962), "Experimental Evidence for the Second Postulate of Special Relativity", American Journal of Physics, Volume 30, Issue 4, pp. 297-300
* Fox, J. G. (1965), "Evidence Against Emission Theories", American Journal of Physics 33 (1): 1–17
* Fox, J. G. (1967), "Constancy of the Velocity of Light," J. Opt. Soc. Am. 57, 967-968
http://mysite.verizon.net/cephalobus_alienus/papers/Fox_1967.pdf

Regards,
 
Histspec said:
Ritz's original theory doesn't involve extinction effects, and therefore it was conclusively ruled out by DeSitter's double stars and the Sagnac effect, both in 1913.

Sorry, but I don't follow you here. Doesn't extinction exist regardless of whether you believe in SR or an emission theory?

But it sounds like a good answer to my original question is simply that the Sagnac effect disproves emission theories, since the Sagnac effect occurs in vacuum, and you don't get extinction in a vacuum.

I guess it's odd, though, that the edu-observatory.org page doesn't even mention the Sagnac effect in its discussion of moving source tests. Maybe that's because the waters are muddied by the existence of multiple versions of the emission theory that make different statements about what happens in reflection: http://en.wikipedia.org/wiki/Emission_theory#History

Thanks!

[EDIT] Oh, I see, the Fox 1967 paper says that in Ritz's original formulation, he assumed that scattering would leave the velocity of the light unaffected. That seems bizarre to me, but I suppose there was never really any plausible set of physical mechanisms for the Ritz theory anyway.
 
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bcrowell said:
But it sounds like a good answer to my original question is simply that the Sagnac effect disproves emission theories, since the Sagnac effect occurs in vacuum, and you don't get extinction in a vacuum.

It sounds like the Wikipedia article compounds some confusion about extinction. According to the Ewald-Oseen extinction theory, incident radiation suffers extinction from any charge that is relatively free to move in response to the radiation within the specified spatial area regardless of whether its embedded in a vacuum or media (including the charges in the detector). Astronomers though, might be most focused on secondary extinction occurring in intervening matter while the light is in transit.

But since the paths of light are circular in the Sagnac experiment (the mirrors are symmetrically situated), any possible extinction effects from the mirrors should cancel out.
 
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PhilDSP said:
[..]
However, a full analysis of the Sagnac experiments (1913?) and all related ones including the Michelson-Miller experiment a couple of decades later very clearly shows that emission theories do not apply in the case where two light sources having different paths to the detector are compared. If the Ritz theory were correct no shift in phase of the 2 signals would occur, right?

Yes I would think so. But we can trace the disprove of ballistic emission theories to much earlier in time, as I think Einstein understood before writing his 1905 paper. What many people (incl. Ritz?) seem to overlook is the Fizeau experiment that was meant to test the Fresnel drag coefficient. Not only the results were consistent with Fresnel's theory, at the same time the results rejected the whole class of ballistic emission theories.

See also http://en.wikipedia.org/wiki/Fizeau_experiment

Cheers,
Harald
 
I have a few questions regarding this topic:

1) I would like to know a little bit more about these gazillion mentioned by bcrowell:
bcrowell said:
... and it was indirectly inconsistent with a gazillion other experiments, ...
What are some examples of these indirect experiments?

2) I would also be interrested in the most recent experiences disproving the Ritz emission theory.

3) Curious also about te most precise experiences disproving the Ritz theory.

4) Finally, are there some recent experiences putting some opposite evidence, or some remaining doubts?

Thanks,

Michel
 
lalbatros said:
I have a few questions regarding this topic:

1) I would like to know a little bit more about these gazillion mentioned by bcrowell:

What are some examples of these indirect experiments?
One example was mentioned in the foregoing post. :wink:
[..]
3) Curious also about te most precise experiences disproving the Ritz theory. [..]
Perhaps ring laser gyroscopes?
- http://en.wikipedia.org/wiki/Sagnac_effect
 

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