Eli5: why is there a lot of matter but no antimatter if they both appear simultaneously?
In: Physics
There had to have been some ‘process’ in the early universe that treated matter different from antimatter. We actually already know of such a process (namely some part of the weak nuclear interaction) but the difference it creates between matter and antimatter is not large enough to explain how much more matter than antimatter there is in the universe. This means there has to be some other process that we don’t know of that is responsible.
This is actually one of the big unanswered questions in physics. In theory they should have been created in equal measures and then turned back into energy, but there was slightly more matter which became all the stuff in the universe (You, Me, Planet Earth, The Reddit servers, galaxies etc)
We don’t have a definitive answer on that one. The two hypothesis that I hear the most is
1) There was much more matter and antimatter at the big bang, but there was a little bit more matter. So after everything annihilated itself with antimatter-matter reaction, the little bit more of matter is what make our universe.
2) There is this view that antimatter could just be matter but going backward in time. Maybe at the big bang two universe were created. One going forward in time made of matter and one going backward in time made of antimatter. I know it’s weird, it’s melting my brain too.
[https://www.youtube.com/watch?v=IutpODdk4rU](https://www.youtube.com/watch?v=IutpODdk4rU)
Here a video about it. But of course it’s all mostly speculation, and different scientist disagree with each other on the subject.
This is a very good question, and one that physicists are still looking for an answer for. Based on the current theory, the big bang probably should have created equal amounts of matter and anti-matter. Matter and anti-matter don’t get along well, but scientists were expecting to seem clumps of anti-matter in the universe when looking through telescopes, along with occasional explosions when anti-matter drifted into matter. We haven’t observed any of this, which means that the entire universe appears to be made of matter.
Scientists are struggling to come up with an explanation. It could be that for some reason the big bang only created matter, but we don’t know why this would be the case. It is also possible that the anti-matter and matter created by the big bang reacted with each other in a second bang, and that second bang resulted in only matter forming. Or, it could be that our fundamental theory of physics is missing something. Given that we can’t account for 99% of the matter and energy in the universe, which we call dark matter or dark energy, I lean towards this last theory.
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