anti-matter and anti-photons

drakken1985

Granted its not cost effective to produce anti-matter in great amounts; however if one where to apply energy to matter, eventually that matter will release a photon or light. I can't find any information where its not the same with anti-matter. So assuming one can excite anti-matter to give of photons, how would an anti-photon (if thats an accurate discription) behave in our universe. Or is a photon emitted from matter the same as one given off from anti-matter. Can an anti-photon actually exist in this universe, even if it doesn't encounter another photon

The_Duck

This. The photon is its own antiparticle.

Rorkster2

If a photon is its anti partical then I take it that photon=anti photon? If so then does this imply that if a photon collides with another photon they won't scatter, they'll anihalate?

The_Duck

Yes, photons can "annihilate," producing charged particles like electrons. It's possible to send two sufficiently energetic gamma ray photons at each other and have them collide and produce an electron-positron pair. This is exactly the reverse of the annihilation of an electron-positron pair into photons.

It's also possible for photons to scatter off each other. This can happen basically when the electron-positron pair that get produced in the photon-photon collision immediately annihilate each other again and turn back into photons. So you started with two photons and ended with two photons, so effectively the photons scattered off each other. Since this requires two interactions--the initial production of the electron-positron pair and then its subsequent annihilation--the probability of this "light-by-light scattering" event happening is pretty low.

Rorkster2

So a gamma ray collision can only produce an electron/positron or is their another partical that can pop up? In an electron-positron collision how many photons are emitted? It's sounding like 2 gamma ray photons collide and can form 1 electron and 1 positron, but a photon is massles and we can measure the mass of an electron, wouldn't that essentually create energy?

The_Duck

Gamma ray collisions can produce any charged particle and it's antiparticle, or, if they gamma rays have lots of energy to spare, they can produce many particles at once. This is just like in particle accelerators where we collide particles like protons with very high energy and lots of other particles come out, since there is so much energy to go around. The idea here is that mass is a form of energy, so if we collide any two particles, including photons, that have enough energy, new particles can be formed in the collision, which the mass of the new particles coming out of the total energy available in the collision. *Energy* is conserved, but not *rest mass*--the energy of gamma rays can be turned into the mass energy of electrons and positrons during a collision.