Do Photons Have Mass When Moving Close to the Speed of Light?

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Photons are defined as packets of energy that travel at the speed of light and have zero rest mass, meaning they do not gain mass even when moving close to light speed. The equation E=mc^2 is not applicable to photons since they do not possess rest mass; instead, the relationship E^2 = p^2 c^2 + m^2 c^4 is more relevant, where momentum (p) is linked to energy. Discussions highlight that while the effective velocity of light can change during refraction, the speed of individual photons remains constant. The concept of mass in relation to light is clarified, emphasizing that anything moving at light speed cannot have mass. Overall, photons are best understood as energy quanta rather than traditional particles.
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They Say Photons Move In The Velocity Nearly Equal To Light ...
If A Body Approaches Velocity Of Light The Mass Increases ...

If U Think The Photons As Packets Of Energy Then E=mc^2 Or
E/c^2 Is M Then... Will Energy Should Have Mass...
 
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Mr.Socrates said:
They Say Photons Move In The Velocity Nearly Equal To Light ...
"They" should say that photons, being light, move exactly at the speed of light.

If A Body Approaches Velocity Of Light The Mass Increases ...
That is one way of looking at massive particles (particles with a non-zero rest mass). But it doesn't apply to photons, which have zero rest mass.
If U Think The Photons As Packets Of Energy Then E=mc^2 Or
E/c^2 Is M Then... Will Energy Should Have Mass...
A better formula to use is this:
E^2 = p^2 c^2 + m^2 c^4, where "m" is the rest mass of the particle (which is zero for a photon) and "p" is its momentum.
 
then what do u think is momentum related with ... i think there is a small conection with mass... photon whose " rest mass " is only 0 not the mass when it moves... so the momentum should vary in each case where the velocity varies like in refraction...
+
 
The momentum of a photon is related to its energy. (E = pc)

Note: The effective (group) velocity of light varies during refraction, but not the photon speed.
 
ok if the group velocity changes won't there be a change in phase velocity with some uncertainity... if the v changes the p changes.. what will be the velocity change in the relativistic frame of referance and if so there is a v change it is approaching c so what will happen to mass
 
Anything that moves at the speed of light has no point-mass, so it is always in motion so it cannot have mass. Even if it had a tiny-tiny-tiny amount of mass, with the speed of light multiplied to it it would be gigantic.

Sorry Doc, Didn't see your explanation.
 
Has anybody noticed that Socrates posts with all words capitalized, or all lower-case?
 
Photons are actually just light. Photon is a model, a short name for the fact that light has quanta of energy that sometimes show particle like beahvior on interaction with matter.

They are not separate particles that happen to travel at the speed of light.

Good observation, Mk!

http://www.geocities.com/physics_all"
 
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