Of course I was thinking to objects moving relative to humans frame of reference.
Yet, I am not sure this is absolutely necessary, but it may help a discussion.
I also implied inertial frames of reference, which is maybe really necessary.
I was asking this question because I could not find so many examples.
"
What is the experimental basis of Special Relativity?" doesn't give so many.
I reproduce them below.
The OPERA results are interresting in this respect.
They remind us that electromagnetic waves, neutrinos and other things share the same limit speed.
I did not see measurements of fast neutrons, maybe they are not fast enough in our labs.
I did not see astronomical objects.
Naïvely speaking, a huge database of observed speeds (relative to us) would be an overwhelming proof of SR, I believe.
Specially if objects like neutrinos are involved, which are supposedly not related to the electromagnetic interactions.
Of course any sort of object, including planets, screws of plasma jets could be useful.
It is difficult to decide what "close to c" may exactly mean.
However, in the end the data should illustrate that c is indeed the limit.
Massless particles are of course the most convincing.
However, speeds of protons measured as function as their energy could also be convincing: would you know about such measurements? What about data from cyclotrons, are the energies large enough? What about CERN data?
I have no doubt that such speed data are common.
But it would be interresting to have them compiled, somehow.
Experiments that Show the Limiting Velocity c
Alspector et al., Phys. Rev. Lett. 36, pg 837 (1976).
A comparison of neutrino and muon velocities, at Fermilab.
Kalbfleisch et al., Physics Review Letters 43, pg 1361 (1979).
A comparison of muon, neutrino, and antineutrino velocities over a range of energies, at Fermilab.
Guiragosian et al., Phys. Rev. Lett. 34 no. 6 (1975), pg 335.
Relative velocity measurements of 15 GeV electrons and gammas. No significant difference was observed within ~2 parts in 107. See also Brown et al.
G.L. Greene et al.,“Test of special relativity by a determination of the Lorentz limiting velocity: Does E=mc2?” Physical Review D 44 (1991) R2216.
An analysis combining the results of several experiments gives the result that the Lorentz limiting velocity must be equal to the speed of light to within 12 parts per million.
Stodolsky, “The Speed of Light and the Speed of Neutrinos”, Phys. Lett. B201 no. 3 (1988), pg 353.
A comparison of neutrino and photon speeds from supernova SN1987A puts a limit of about 1 part in 108 on their speed difference.
