Question

I understand the general argument that, without some breaking of symmetry, all the matter in the universe would annihilate all the anti-matter and we'd be left with nothing but photons and some other relativistic particles. I've read several posts and articles claiming there must be a broken CP symmetry somewhere for a small fraction of baryons to be left over. I have never seen any discussion of why a broken time symmetry couldn't result in the same imbalance.

Let's say, for the sake of argument, that every second was shorter than the second that came before by a teeny-tiny amount. Is there an argument to be made in particle physics that the deceleration of time can favor one form of matter over the other?

Answer 1

The asymmetry between matter and antimatter in the universe is due to a small CP symmetry violation observed in particle physics, particularly in K-meson decays, rather than a deceleration of time.

The small asymmetry resulted in slightly more matter than antimatter in the early universe, leaving the matter-dominant universe we see today.

Step-by-step explanation:

Your question addresses the intriguing asymmetry between matter and antimatter in the universe, and whether a broken time symmetry could account for why we see more matter than antimatter.

According to current scientific understanding, especially in the realm of particle physics, the discrepancy comes from a slight asymmetry in physical laws, particularly during certain particle decays such as the decay of neutral K-mesons, which produce slightly more matter than antimatter.

This broken CP (charge parity) symmetry is responsible for the imbalance observed, leading to a universe dominated by matter.

While your idea of time deceleration is creative, it is not currently supported by experimental evidence or theoretical models in physics.

Time symmetry breaking has not been observed in such a way that could favor matter over antimatter. Instead, the asymmetry we see is thought to arise from CP violation within the basic forces, a phenomenon that has been studied and confirmed in various experiments with particles like the K-mesons.

If the universe exhibited perfect symmetry, there would've been near-total annihilation of both matter and antimatter, leaving very little to form the stars and galaxies.

However, because of the slight asymmetry, a minuscule fraction of matter survived, which now makes up the observable universe. This small difference highlights a fundamental and remarkable aspect of our universe, and it is a subject of great interest for physicists.