Dear Dr B: If photons have a mass, would this mean special relativity is no longer valid?

Einstein and Lorentz.[Image: Wikipedia]

�[If photons have a restmass] would that mean the whole business of the special theory of relativity being derived from the idea that light has to go at a particular velocity in order for it to exist/Maxwell�s identification of e/m waves as light because they would have to go at the appropriate velocity is no longer valid?�


~ Brian Clegg

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