Question

do photons have the most energy than any other particle
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Answer 1

Explanation:

Photons have a rest mass of zero, which just means that you will never observe a photon standing still, or moving with any velocity less than c, the speed of light. Photons have an energy, E, given by Quantum Mechanics, which states that;

E=hf, where f is its frequency in Hz, and h is Plank’s constant.

Einstein derived the famous equation, as part of his Special Theory of Relativity, which states that; E=mc^2.

If we just equate these two expressions, for a photon, we get;

mc^2 = hf, so, m = hf/c^2

Then, the momentum of the photon, p, is given by; p = mv = mc = hf/c.

So, in words, we can say that a photon has mass because it has energy, and it has momentum because it has mass. These three formulae have been confirmed many times, in many and varied, different kinds of experiments. They are all very well established.

There is another formula from Special Relativity, also derived by Einstein, which gives the mass of an object, m, at a velocity, v, in terms of its rest mass, m(0). It states that;

m = m(0) / (1 - v^2/c^2)^1/2

For a photon, m(0)= 0, so at all values of v less than c, m = 0, i.e. the photon doesn't exist at such velocities. When, however, v=c, m = 0/0, which is indeterminate, so m could have any value; it happens to have the value hf/c^2.

Another group of particles which also have zero rest mass are ‘gluons’. Photons carry the electromagnetic force, and gluons carry the strong nuclear force, which binds protons and neutrons together in the nucleus of an atom.

There may be one other particle with zero rest mass, but it is, as yet, undetected by any experiment. It carries the gravitational force, and is called a ‘graviton’. Opinion is divided over the issue of its existence. It is actually predicted by Superstring Theory, but the status of this theory is as much in doubt as the status of the graviton that it predicts