C, P, and T Symmetries

Symmetry is an interesting topic that extends beyond highschool geometry. In fact, it was/is believed that particles and forces should obey the laws of symmetry. C symmetry, known as charge conjunction, is the idea that particles and their respective antiparticles should obey the same laws. It is believed that all of the known forces except for one obey this(electromagnetism, the strong nuclear force, and gravity obey, weak nuclear force does not).

P symmetry means that particles and their mirror images should obey the same laws. The discovery that the weak force does not obey P symmetry means that a chiral universe, one where spins of particles like electrons were in the opposite direction, would be completely different than our own. This is interesting to say the least, because an abstract notion of spin or handedness of subatomic particles doesn't seem to have much bearing on macroscopic scales (at least to us laymen).

T symmetry is the one that relates to being able to rewind time. Newtonian mechanics assumes T symmetry as there should be no difference between moving forward or backward as long as you have all of the initial conditions and equations at play.

The issue at hand is that a theory that both incorporates Einstein's theory of relativity with quantum mechanics must follow these three symmetries. This is obviously a conundrum, because theoretical physicists are unable to think of any such theory of our universe. (There is even recent talk of a so-called 5th force that is needing to undergo a strong peer review process to verify if it is valid). Without a doubt, we are currently without a complete theory of our universe. Perhaps the search and understanding of dark matter and dark energy will enlighten us to a more solid theory.

Gif from Wikipedia