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Ferdricklove
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Does a photon have a mass?
Did you look on the Relativity FAQ list for the answer to this Frequently Asked Question?Ferdricklove said:Does a photon have a mass?
According to the theory of relativity, photons do not have a rest mass. However, they do have a form of mass called relativistic mass, which is a measure of their energy and momentum. Therefore, the answer is both yes and no, depending on the context.
Photons have energy because they are constantly moving at the speed of light. In the theory of relativity, energy and mass are equivalent, so the energy of a photon can be thought of as its mass in a different form. This is why photons are sometimes referred to as "massless particles."
Yes, photons can be affected by gravity because they have energy and momentum, which are affected by gravity according to the theory of general relativity. This is why light can be bent by massive objects, such as stars, in a phenomenon known as gravitational lensing.
The rest mass of a photon does not change when it travels through a medium. However, its speed and direction can be affected by the interactions with the particles in the medium, which can alter its energy and momentum. This is why light can appear to slow down when passing through certain materials.
Since photons do not have a rest mass, their mass cannot be measured in the traditional sense. However, their energy and momentum can be measured, and this can be used to calculate their relativistic mass. This is often done through experiments involving the interaction of photons with other particles or fields.