Thread: if a photon of light has 0 rest mass but it has momentum then ..
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Old 24-April-2008, 02:58 AM
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tommac tommac is offline
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so is it safe to say that the momentum of light diminishes as space-time expands and the momentum of light increases as space-time contracts.

In other words ... as time slows down light gains momentum as time speeds up light loses momentum.












Quote:
Originally Posted by cjl View Post
No. For a photon, momentum is dependent on energy, which is proportional to frequency. That can be determined with the equation E2=(pc)2+(mv2)2. As photons are massless, the second term drops out, simplifying the equation to E2=(pc)2 in that case.

Oh, and you are right about the momentum going to infinity for a massive object as it approaches c.