Photons

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ollyoxenfree
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Photons

Post by ollyoxenfree » Sun Dec 05, 2010 4:07 am

It appears photons have almost unlimited energy, yet they have no mass, unless I am mistaken isn't this against E=mc2? Since obviously there is not a very big chance that one person is going to tear down relativity, I will assume that there is an answer that I am missing and it is fortunate that the title includes "no question to easy" I guess :).

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Chris Peterson
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Re: Photons

Post by Chris Peterson » Sun Dec 05, 2010 9:49 am

ollyoxenfree wrote:It appears photons have almost unlimited energy, yet they have no mass, unless I am mistaken isn't this against E=mc2? Since obviously there is not a very big chance that one person is going to tear down relativity, I will assume that there is an answer that I am missing and it is fortunate that the title includes "no question to easy" I guess :).
Photons don't have unlimited (or even "almost unlimited") energy. They have a very specific, and individually small energy, E = h*c/lambda, where h is Planck's constant and lambda is the wavelength of the photon.

Furthermore, photons don't have zero mass. They are members of a class of particles that have zero rest mass. However, such particles are never at rest, and have a momentum, which means they also have an equivalent mass- which works out to be exactly what you'd expect from E=mc^2.
Chris

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