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On 5/9/10 5:00 PM, Henry (Ralph) Wilson DSc wrote:
> OWLS from a moving source has never been measured.

http://math.ucr.edu/home/baez/physics/Relativity/SR/experiments.html#one-way_tests

> 3.2 One-Way Tests of Light-Speed Isotropy
>
> Note that while these experiments clearly use a one-way light path and find isotropy, they are inherently unable to rule out a large class of theories in which the one-way speed of light is anisotropic. These theories share the property that the round-trip speed of light is isotropic in any inertial frame, but the one-way speed is isotropic only in an æther frame. In all of these theories the effects of slow clock transport exactly offset the effects of the anisotropic one-way speed of light (in any inertial frame), and all are experimentally indistinguishable from SR. All of these theories predict null results for these experiments. See Test Theories above, especially Zhang (in which these theories are called “Edwards frames”).
>
> Cialdea, Lett. Nuovo Cimento 4 (1972), pg 821.
> Uses two multi-mode lasers mounted on a rotating table to look for variations in their interference pattern as the table is rotated. Places an upper limit on any one-way anisotropy of 0.9 m/s.
>
> Krisher et al., Phys. Rev. D, 42, No. 2, pg 731–734, (1990).
> Uses two hydrogen masers fixed to the Earth and separated by a 21-km fiber-optic link to look for variations in the phase between them. They put an upper limit on the one-way linear anisotropy of 100 m/s.
>
> Champeny et al., Phys. Lett. 7 (1963), pg 241.
> Champeney, Isaak and Khan, Proc. Physical Soc. 85, pg 583 (1965).
> Isaak et al., Phys. Bull. 21 (1970), pg 255.
> Uses a rotating Mössbauer absorber and fixed detector to place an upper limit on any one-way anisotropy of 3 m/s.
>
> Turner and Hill, Phys. Rev. 134 (1964), B252.
> Uses a rotating source and fixed Mössbauer detector to place an upper limit on any one-way anisotropy of 10 m/s.
>
> Gagnon, Torr, Kolen, and Chang, Phys. Rev. A38 no. 4 (1988), pg 1767.
> A guided-wave test of isotropy. Their null result is consistent with SR.
>
> T.W. Cole, “Astronomical Tests for the Presence of an Ether”, Mon. Not. R. Astr. Soc. (1976), 175 93P-96P.
> Several VLBI tests sensitive to first-order effects of an æther are described. No æther is detected, with a sensitivity of 70 m/s.
>
> Ragulsky, “Determination of light velocity dependence on direction of propagation”, Phys. Lett. A, 235 (1997), pg 125.
> A “one-way” test that is bidirectional with the outgoing ray in glass and the return ray in air. The interferometer is by design particularly robust against mechanical perturbations, and temperature controlled. The limit on the anisotropy of c is 0.13 m/s.
>
> 3.3 Tests of Light Speed from Moving Sources
>
> If the light emitted from a source moving with velocity v toward the observer has a speed c+kv in the observer's frame, then these experiments place a limit on k. Many but not all of these experiments are subject to criticism due to Optical Extinction.
>
> Experiments Using Cosmological Sources
>
> Comstock, Phys. Rev. 10 (1910), pg 267.
> DeSitter, Koninklijke Akademie van Wetenschappen, vol 15, part 2, pg 1297–1298 (1913).
> DeSitter, Koninklijke Akademie van Wetenschappen, vol 16, part 1, pg 395–396 (1913).
> DeSitter, Physik. Zeitschr. 14, 429, (1913) http://www.datasync.com/~rsf1/desitter.htm.
> DeSitter, Physik. Zeitschr. 14, 1267, (1913) http://www.datasync.com/~rsf1/desitter.htm.
> Zurhellen, Astr. Nachr. 198 (1914), pg 1.
> Observations of binary stars. k < 10−6. These are all subject to criticism due to Optical Extinction.
>
> K. Brecher, “Is the Speed of Light Independent of the Velocity of the Source?”, Phys. Rev. Lett. 39 1051–1054, 1236(E) (1977).
> Uses observations of binary pulsars to put a limit on the source-velocity dependence of the speed of light. k < 2×10−9. Optical Extinction is not a problem here, because the high-energy X-rays used have an extinction length considerably longer than the distance to the sources.
>
> Heckmann, Ann. d. Astrophys. 23 (1960), pg 410.
> Differential aberration, galaxies versus stars. This experiment is subject to criticism due to Optical Extinction.
>
> Observations of Supernovae
> A supernova explosion sends debris out in all directions with speeds of 10,000 km/s or more (known from Doppler broadening of spectral lines). If the speed of light depended on the source velocity, its arrival at Earth would be spread out in time due to the spread of source velocities. Such a time spread is not observed, and observations of distant supernovae give k < 5×10−9. These observations could be subject to criticism due to Optical Extinction, but some observations are for supernovas considerably closer than the extinction length of the X-ray wavelengths used.
>
> Experiments Using Terrestrial Sources
>
> Alvaeger F.J.M. Farley, J. Kjellman and I Wallin, Physics Letters 12, 260 (1964).
> Arkiv foer Fysik, Vol 31, pg 145 (1965).
> Measured the speed of gamma rays from the decay of fast π0 (~0.99975 c) to be c with a resolution of 400 parts per million. Optical extinction is not a problem for such high-energy gamma rays. The speed of the π0 is not measured, but is assumed to be similar to that measured for π+ and π−.
>
> Sadeh, Phys. Rev. Lett. 10 no. 7 (1963), pg 271.
> Measured the speed of the gammas emitted from e+e− annihilation (with center of mass v/c ~0.5) to be c within 10%.
>
> This experiment was criticized in Lo Savio, Phys. Lett. A, 1988, Vol 133, pg 176. It is certainly true that at the instant of annihilation the e+ need not be traveling in the same direction it had initially, or have the same speed (most annihilations occur at very low energy as the positrons stop). This experiment is inconclusive at best.
>
> Babcock and Bergmann, Journal Opt. Soc. Amer. Vol. 54, pg 147 (1964).
> This repeat of Kantor's experiment in vacuum shows no significant variation in the speed of light affected by moving glass plates. Optical Extinction is not a problem. k < 0.02.
>
> Filipas and Fox, Phys. Rev. 135 no. 4B (1964), pg B1071.
> Measured the speed of gamma rays from the decay of fast π0 (~0.2 c) in an experiment specifically designed to avoid extinction effects. Their results are in complete disagreement with the assumption c+v, and are consistent with SR. k < 0.5 with a confidence level of 99.9%.
>
> Beckmann and Mandics, “Test of the Constancy of the Velocity of Electromagnetic Radiation in High Vacuum”, Radio Science, 69D, no. 4, pg 623 (1965).
> A direct experiment with coherent light reflected from a moving mirror was performed in vacuum better than 10−6 torr. Its result is consistent with the constant velocity of light. This experiment is notable because Beckmann was a perennial critic of SR. Optical Extinction is not a problem.
>
> Operation of FLASH, a free-electron laser, http://vuv-fel.desy.de/.
> A free-electron laser generates highly collimated X-rays parallel to the relativistic electron beam that is their source. If the region that generates the X-rays is L meters long, and the speed of light emitted from the moving electrons is c+kv (here v is essentially c), then at the downstream end of that region the minimum pulse width is k(L/c)/(1+k), because light emitted at the beginning arrives before light emitted at the downstream end. For FLASH, L=30 meters, v=0.9999997 c (700 MeV), and the observed X-ray pulse width is as short as 25 fs. This puts an upper limit on k of 2.5×10−7. Optical extinction is not present, as the entire process occurs in very high vacuum.
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