In this case, the question is why matter vastly predominates over antimatter, when it’s not clear from nature why it should:
An international collaboration of theoretical physicists has published a new calculation relevant to the search for an explanation of the predominance of matter over antimatter in our universe. The new calculation gives a more accurate prediction for the likelihood with which kaons decay into a pair of electrically charged pions vs. a pair of neutral pions.DOE/Brookhaven National Laboratory, “New calculation refines comparison of matter with antimatter” at ScienceDaily
Our physics color commentator Rob Sheldon writes to say,
Short summary: an extensive calculation of the decay of kaons (a subatomic particle) confirmed that the “standard particle theory” put together in 1979, accurately describes the experimental data.
This dashes yet another attempt to find something that the standard model could not explain. Surprisingly, this is what depresses particle theorists, who have yet to find anything new in the last 40 years, despite thousands of publications. This is why Sabine Hossenfelder argues that there is something wrong with the entire field that has spent $billions without progress.
What was the motivation for this incredibly lengthy calculation?
The Big Bang model claims that the matter of the universe was made out of pure energy in the beginning, beresheet. Particle symmetry would suggest that there should be equal amounts of anti-matter as matter. But everything we look at is normal matter. Furthermore, if some distant galaxy was made from antimatter, there would be a glowing “wall” separating it from matter galaxies, where their matter and antimatter collide and turn into gammarays. Astronomers report there just aren’t any glowing walls in their observations. So the cosmological question has been “Where is all the anti-matter?”
Particle physicists argue that quirk of nature has produced only antimatter in the BB. The CP-symmetry violation (1980 Nobel Prize) was the hoped-for reason that the universe is made of matter. The experiments said that the effect was really, really small. That pretty much eliminates CP-symmetry violation as the cause for our unusual universe. The theorists doubted them, so they did this extensive calculation, which said the effect was really, really small. Here’s the money quote:
“Any differences in matter and antimatter that have been observed to date are far too weak to explain the predominance of matter found in our current universe,” he continued.
And now the physics explanation.
The 1980 Nobel prize in Physics was awarded for the discovery of CP (charge-parity) symmetry violation that permitted more matter than antimatter to arise in “weak interaction” decays.
Now there are 4 fundamental forces in nature arranged by increasing strength: gravitational, electromagnetic, weak, and strong.
We’ve never found anti-gravity, so there is no symmetry law to break there; every bit of matter just keeps adding to the total. So even though it is 34 orders of magnitude smaller than the next force, this sum just keeps getting bigger, dominating the other forces once there are more than 10^34 particles in the box.
The electromagnetic force comes in + and – flavors, which normally neutralize in objects larger than a dust grain. It dominates in the size range of molecules and atoms, holding negative electrons to their positive nuclei. The electromagnetic symmetry is not broken in particle physics.
The strong force, which holds positively charged protons together in the nucleus despite their electromagnetic repulsion, has a symmetry that is not broken in particle physics.
That leaves the weak force, which holds a proton and an electron together inside a neutron, as the only force that violates symmetry in particle physics. This calculation, involving 63-million particle reactions, supercomputers and brand new computer science techniques, was performed to see if the standard model weak force explained the results of kaon (a subatomic particle) decay.
It did. Sabine is right again. Particle physics and BB models still do not agree. And the rest of the article is spin.