RE: Matter and Antimatter – An Explosive Couple! (Particle Physics Series – Episode 4B)

[irelandscape]

Hi, thanks for a very interesting article.
I have 2 questions.

Does the photon itself have its anti-particle?

If our universe was made mostly of anti-matter, instead of matter, would the laws of physics be any different?

Thanks!

Comments

[muphy]

Does the photon itself have its anti-particle?

Yes, the photon has an anti-particle... itself :-)

If our universe was made mostly of anti-matter, instead of matter, would the laws of physics be any different?

That is a very interesting question.

My gut instinct would be to say yes: If they were identical for matter and antimatter, that would mean a perfect symmetry between matter and antimatter, which is obviously not observed.

However, if you imagine that all matter in the universe changed to antimatter in an instant, I am not sure you would notice a difference in your daily life. The consequence of differences in physics laws would be unnoticeable on a human timescale. Only over an extensive amount of time, maybe eons, the slight assymetry would maybe show up as a gradual increase of background gamma radiations over the ages.

You can also say that the terms matter and antimatter are relative. The inhabitants of an universe where antimatter is favored would call it matter, because that's what they are made of, and vice versa (our matter would be their antimatter). ;-)

[procrastilearner]

I think the photon being a boson (integer spin) is its own antiparticle.

I think if the universe was antimatter everything would be just the same.

Per wikipedia:

Antimatter may exist in relatively large amounts in far-away galaxies due to cosmic inflation in the primordial time of the universe. Antimatter galaxies, if they exist, are expected to have the same chemistry and absorption and emission spectra as normal-matter galaxies, and their astronomical objects would be observationally identical, making them difficult to distinguish.

I seem to remember that one decay pathway for some antiparticle is slightly different but thats about it.

[lemouth]

I think the photon being a boson (integer spin) is its own antiparticle.

This is not a generality, The W-boson is charged and we have thus W⁺ and W^- particles around. None of them, are however classified as 'matter' as they are more connected to the interaction side.

In the case of the photon, it is however true that it is its own antiparticle.

[irelandscape]

Ah, thanks for the clarification!

[muphy]

Thank you, for the great question!

[lemouth]

Does the photon itself have its anti-particle?

No, the photon is its own antiparticle.

If our universe was made mostly of anti-matter, instead of matter, would the laws of physics be any different?

Probably not. We should just reverse a few signs here in there in the equations :)

[muphy]

Probably not. We should just reverse a few signs here in there in the equations :)

ha! a disagreement (See my response to @irelandscape 's question).
Cool, That might open an interesting discussion :-)

[lemouth]

At the end, I see just this as a rewording of what is a particle and an antiparticle. Therefore, things should not change :)