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I always wonder why photon is its own anti matter. If it was not so, we wouldn't be able to study anti matter with lasers for example. Also, why is the anti pa

I always wonder why photon is its own anti matter. If it was not so, we wouldn't be able to study anti matter with lasers for example. Also, why is the anti particle pair of a charged particle the opposite charge, but neutral particle/anti particle pair are both chargless? Though it does make sense that in order to cancel each other out, it must be so.. I would say we live in a strange world but I don't know if a non strange world would even exist.

danbruc 10y ago
Also, why is the anti particle pair of a charged particle the opposite charge, but neutral particle/anti particle pair are both chargless? That's just the definition of an antiparticle - same as the particle put opposite charges. Though it does make sense that in order to cancel each other out, it must be so.. That's right, this is required to maintain charge conservation in annihilation processes.
- MereInterest 10y ago
  > That's just the definition of an antiparticle - same as the particle put opposite charges. Well, a bit more is needed. If a particle has no charge, then it is possible for it to be its own antiparticle, but it is not necessarily so. The photon is neutral and is its own antiparticle. The neutron, on the other hand, is neutral but is distinct from the antineutron. It is still an open question whether the neutrino is its own antiparticle.
  - danbruc 10y ago
    If a particle has no charge, then it is possible for it to be its own antiparticle, but it is not necessarily so. [....] The neutron, on the other hand, is neutral but is distinct from the antineutron. The neutron is only electrically neutral, there are also weak isospin and color charge. Antimatter is not only concerned with electrical charge but with charges in general. In case of the neutron and antineutron this becomes obvious if you compare the quark content of both.
    - hwillis 10y ago
      wikipedia: https://en.wikipedia.org/wiki/Charge_(physics) https://en.wikipedia.org/wiki/Charge_(physics)
eternalban 10y ago
> I always wonder why photon is its own anti matter. I speculate that that is because Photons are 'transcendent' (in some some sense).

danbruc 10y ago

Also, why is the anti particle pair of a charged particle the opposite charge, but neutral particle/anti particle pair are both chargless? That's just the definition of an antiparticle - same as the particle put opposite charges. Though it does make sense that in order to cancel each other out, it must be so.. That's right, this is required to maintain charge conservation in annihilation processes.

MereInterest 10y ago
> That's just the definition of an antiparticle - same as the particle put opposite charges. Well, a bit more is needed. If a particle has no charge, then it is possible for it to be its own antiparticle, but it is not necessarily so. The photon is neutral and is its own antiparticle. The neutron, on the other hand, is neutral but is distinct from the antineutron. It is still an open question whether the neutrino is its own antiparticle.
- danbruc 10y ago
  If a particle has no charge, then it is possible for it to be its own antiparticle, but it is not necessarily so. [....] The neutron, on the other hand, is neutral but is distinct from the antineutron. The neutron is only electrically neutral, there are also weak isospin and color charge. Antimatter is not only concerned with electrical charge but with charges in general. In case of the neutron and antineutron this becomes obvious if you compare the quark content of both.
  - hwillis 10y ago
    wikipedia: https://en.wikipedia.org/wiki/Charge_(physics) https://en.wikipedia.org/wiki/Charge_(physics)

eternalban 10y ago

> I always wonder why photon is its own anti matter. I speculate that that is because Photons are 'transcendent' (in some some sense).