Monday, 8 January 2018

special relativity - Constancy of speed of light in vacuum?




Have scientists tried their best to calculate speed of light in vacuum? It seems very absurd to me that light of all frequencies have same velocity in space. Can someone find in future if this speed in reality differ to even some small amount?



Answer



What you describe is the phenomenon called optical dispersion. For example in most optical media the refractive index and therefore the velocity of light depend on frequency. The question is whether empty space shows the same effect.


This has been studied as part of attempts to detect any granularity in spacetime due to quantum gravity effects - short wavelengths should be affected more then long wavelengths by any underlying granularity. Light emitted by distant quasars or gamma ray bursters is inspected for any signs of dispersion, but so far none has been detected.


So experiment finds that the speed of light in vacuum is independent of frequency.


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