How can we actually prove that photon is its own antiparticle?

Question

As we know that photon is its own antiparticle so how can we confidently say this is true? Is there any theory that describes it?

That is a necessary feature of, for instance, QED which is the physical theory that can lay claim to the most precisely tested agreement between theory and experiment in all of science. That's pretty much as good as 'proof' gets. This isn't mathematics. — dmckee --- ex-moderator kitten, Aug 28 '17 at 17:31
Yes. Quantum ElectroDymanics (QED) is the theory of light in terms of photons. — dmckee --- ex-moderator kitten, Aug 28 '17 at 17:38

score 1 · Answer 1 · answered Aug 28 '17 at 16:22

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This is part of the standard model. But experimentally, two photons may collide to form an electron-positron pair.

answered Aug 28 '17 at 16:22

Dr Xorile

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A single photon can spontaneously convert to an electron-positron pair under certain conditions, so this proves nothing about the anti-particle of the photon. – StephenG - Help Ukraine Aug 28 '17 at 16:29
@StephenG not on its own, while conserving energy and momentum. But the point of two photons colliding to form an electron position pair is that photon number is clearly not a conserved quantity, unlike lepton numbers (with a bit of flooding over vector bosons in weak interactions) – PhillS Aug 28 '17 at 16:41
@dr-xorile You're missing the point. The production of a pair of antiparticles by a photon or multiple photons does not imply anything about a photon being it's own anti-particle (or otherwise). – StephenG - Help Ukraine Aug 28 '17 at 16:48
@StephenG so it is not confirmed that photon has it's antiparticle Right? – Mental Shakya Aug 28 '17 at 17:13
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I would say we had no evidence at this time that the photon's antiparticle is not a photon. – StephenG - Help Ukraine Aug 28 '17 at 17:24
@StephenG so is it wrong to say that light is made up of combination of photon and anti photon? – Mental Shakya Aug 28 '17 at 17:32
It's not exactly wrong, but it's misleading in that you may give the impression that there is a difference between the photo and it's anti-particle. – StephenG - Help Ukraine Aug 28 '17 at 18:08
@mentalshakya The standard theory describing light and how it interacts with matter, QED, says that the photon is its own antiparticle, and there is zero evidence contradicting this. All the predictions of QED match observations extremely well, so we have great confidence in it. – PM 2Ring Aug 28 '17 at 19:08
A collision of two photons producing an electron-positron pair has not been experimentally observed to date. – safesphere Aug 29 '17 at 02:56
Maybe in future it will be @safesphere – Mental Shakya Aug 29 '17 at 09:43

score -3 · Answer 2 · answered Aug 28 '17 at 16:25

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Due to the photon being electrically neutral, it can be said to be its own antiparticle, given that an antiparticle has the opposite charge as the original particle.

answered Aug 28 '17 at 16:25

NaturalNonThinker

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Neutrinos are electrically neutral, but there is a clear distinction between neutrinos and anti-neutrinos – PhillS Aug 28 '17 at 16:38
@PhillS is there any relation between photon and neutrinos.? – Mental Shakya Aug 28 '17 at 17:14
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NaturalNonThinker, your post attempts to draw a straight line between neutrality and a particle being it's own antiparticle. Any clear counter example calls that in to question. Mind you, I would have used the neutron or the neutral kaon as an example because the Fermi or Majorana character of the neutrino is still a matter of inquiry and if they are Majoranic (as predicted by the standard model) they would not represent a good example. @PhillS – dmckee --- ex-moderator kitten Aug 28 '17 at 17:29
So what is the good example @dmckee – Mental Shakya Aug 28 '17 at 17:38
The neutron or the neutral kaon. Just like I said. – dmckee --- ex-moderator kitten Aug 28 '17 at 17:39

How can we actually prove that photon is its own antiparticle?

2 Answers2