Home » News & Blogs » Dear Dr B: If photons have a mass, would this mean special relativity is no longer valid?
Bookmark and Share
Backreaction

Dear Dr B: If photons have a mass, would this mean special relativity is no longer valid?

15 May 2016, 06:17 UTC
Dear Dr B: If photons have a mass, would this mean special relativity is no longer valid?
(200 words excerpt, click title or image to see full post)

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it to exist/Maxwell’s identification of e/m waves as light because they would have to go at the appropriate velocity is no longer valid?”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(This question came up in the discussion of a recent proposal according to which photons with a tiny restmass might cause an effect similar to the cosmological constant.)Dear Brian,The short answer to your question is “No.” If photons had a restmass, special relativity would still be as valid as it’s always been.The longer answer is that the invariance of the speed of light features prominently in the popular explanations of special relativity for historic reasons, not for technical reasons. Einstein was lead to special relativity contemplating what it would be like to travel with light, and then tried to find a way to accommodate an observer’s motion with the invariance of the speed of light. But the derivation of special relativity is much more general than that, and postulating that the speed of light is invariant is unnecessary.Special ...

Latest Vodcast

Latest Podcast

Advertise PTTU

NASA Picture of the Day

Astronomy Picture of the Day

astronomy_pod