Primordial Hum

[Psnarf]

"In the first few hundred thousand years after our Universe was born, a primordial hum ripped through a plasma of superheated particles. Scientists are listening in with the hope of gaining new insights about the mysterious force known as dark energy."

https://www.bbc.com/future/article/2023 ... e-universe

[Psnarf]

If there were equal parts of matter particles and anti-matter particles way back when, why didn't everything just annihilate leaving no particles at all? The fact that we now find a lot more matter than anti-matter, suggests something separated the remaining particles at some point in time. Perhaps it was baryon acoustic oscillations that kept a relative handful of anti-matter separated?

[Chris Peterson]

If there were equal parts of matter particles and anti-matter particles way back when, why didn't everything just annihilate leaving no particles at all? The fact that we now find a lot more matter than anti-matter, suggests something separated the remaining particles at some point in time. Perhaps it was baryon acoustic oscillations that kept a relative handful of anti-matter separated?

I think the general view is that there were not an equal number of each at the beginning. That matter outmassed antimatter by a tiny, tiny, tiny percentage.

[Markus Schwarz]

If there were equal parts of matter particles and anti-matter particles way back when, why didn't everything just annihilate leaving no particles at all? The fact that we now find a lot more matter than anti-matter, suggests something separated the remaining particles at some point in time.

This is indeed an unsolved question. The known mechanisms that distinguish between matter and anti-matter are insufficient to explain the observed matter anti-matter asymmetry.