Where has there been any experimental proof that light particles are masseless?

Question

The description of energy and mass

There really is no proof is there?

Answer 1

That is an interesting question as the fact that light bends in a gravitational field can only be explained if the light photons has mass. The fact that photons are moving at the speed of light is not in itself proof that photons don't have mass...The reason for that logic lies with the famous Einstein equation, BUT E=mc^2 is for particles, and a photon is not a particle (strictly speaking) also the mass (m) in the equation actually referes to the particle mass at rest, and light photons are never at rest so the equation doesn't really provide exact results when working with photons.
So yes light photons have mass, its just a big exercises to prove it!

Answer 2

This question comes up in the context of wondering whether photons are really "massless," since, after all, they have nonzero energy and energy is equivalent to mass according to Einstein's equation E=mc2. The problem is simply that people are using two different definitions of mass. The overwhelming consensus among physicists today is to say that photons are massless. However, it is possible to assign a "relativistic mass" to a photon which depends upon its wavelength. This is based upon an old usage of the word "mass" which, though not strictly wrong, is not used much today.

The old definition of mass, called "relativistic mass," assigns a mass to a particle proportional to its total energy E, and involved the speed of light, c, in the proportionality constant:

m = E / c2.

This definition gives every object a velocity-dependent mass.

The modern definition assigns every object just one mass, an invariant quantity that does not depend on velocity. This is given by

m = E0 / c2,

where E0 is the total energy of that object at rest.

If the rest mass of the photon was non-zero, the theory of quantum electrodynamics would be "in trouble" primarily through loss of gauge invariance, which would make it non-renormalizable; also, charge-conservation would no longer be absolutely guaranteed, as it is if photons have vanishing rest-mass. However, whatever theory says, it is still necessary to check theory against experiment.

It is almost certainly impossible to do any experiment which would establish that the photon rest mass is exactly zero. The best we can hope to do is place limits on it. A non-zero rest mass would lead to a change in the inverse square Coulomb law of electrostatic forces. There would be a small damping factor making it weaker over very large distances.

The behavior of static magnetic fields is likewise modified. A limit on the photon mass can be obtained through satellite measurements of planetary magnetic fields. The Charge Composition Explorer spacecraft was used to derive a limit of 6x10-16 eV with high certainty. This was slightly improved in 1998 by Roderic Lakes in a laborartory experiment which looked for anomalous forces on a Cavendish balance. The new limit is 7x10-17 eV. Studies of galactic magnetic fields suggest a much better limit of less than 3x10-27 eV but there is some doubt about the validity of this method.

Answer 3

fairly, easy isn't "massless". For the needs of expertise how physics works, the only element that is fairly massless is the "element particle", theoretical build designed make certain ideas much less complicated to inspect. easy, while that's behaving as a wave, has no mass through fact the seen mass is incomprehensible in that context. while that is behaving as a particle, although if, it has the close-to-0 mass of a photon. in case you will choose to work out a photon (because you seem prepared on experiments and not spelling), lock your self in a depressing place with a wintergreen lifesaver. in case you snap the lifesaver, you will destroy the crystal lattice and launch capacity contained in certainly one of those photons. while you're fortunate, and that is dark sufficient, you will see some! there is no longer something uncertain in any respect approximately E=mc^2, you may coach it to your self while you're clever sufficient to do some basic experiments. Mr.Einstein already did each and all the aggravating artwork for you, the least you may desire to do is to be grateful!

Answer 4

Hi. An atom can give off an unlimited number of photons. If photons had mass this would not be possible. The fact that they travel ONLY at the speed of light with no acceleration can only happen with a mass-less particle.

Answer 5

No where. It is a strongly supported theory.

Most experiments suggest light is without mass but that's the closest we can get at the moment.

Did you know that even though we can measure the speed of light, that number is still a theory? We accept it to be true but every scientist has every fact in his head as a theory. A fact is a strong as the theory supporting it.

Answer 6

Your question is part of the wave-particle duality of light some time acts as it had mass, it bends towards a mass object, and other times it acts as a wave of electromagnetic energy massless.

Answer 7

It is not massless. Relativity has proven that it has mass. Besides, de Broglie's equation, lambda=h/mc also reaffirms this fact.

Answer 8

Einstein was a genius.