What is Charge,Parity, and Time symmetry in physics?

Question

does the weak force break this symmetry

Answer 1

There is a theorem in physics known as CPT theorem.  It states that if you reverse the charge (from positive to negative, but this refers not only to electric charge, but also to weak and strong charges), invert the parity (go to a mirror image of the system) and reverse the time that all the physics will be exactly the same.

The theorem assumes that special relativity applies and that interactions are local.

It use to be thought that parity was a good symmetry.  It was then found that some weak interactions violate this symmetry.  The combined symmetry of CP was then focused on, but alas, this symmetry too was violated.

As far as anyone knows CPT symmetry is a good symmetry.

The problem is, if this symmetry is good, then baryon number should be conserved.  Specifically, the number of matter particles minus the number of antimatter particles should stay the same.

But we also think that the universe started out with as many baryons as antibaryons, so how did we get from there to here?

The is one of the big outstanding problems of physics.  No one really knows how this happened.

This is why there are some physicists that are actively seeking various CP violating processes, to study them so that they can maybe understand how many came to dominate the universe.