[vivzkestrel]

so basically one of the articles talks about why there should be an equal amount of matter and antimatter in the universe but in reality we havent been able to find antimatter, is it possible that our entire observable universe is a small area with matter rich concentration and there exists a much much bigger structure of the order of 1 decillion light years where random areas have concentrations of matter and antimatter and we are unfortunately stuck in the area with matter?

[wongarsu]

That would violate the Cosmological principle - the idea that viewed on a sufficiently large scale, the properties of the universe are the same for all observers. Also the Copernican principle - the idea that our observation point in the universe is pretty average and not overly special.

Of course both of these principles aren't strongly supported by evidence. They are still usually assumed because they keep cosmology sane and verifiable.

[jokellum]

This is something that confused me also. I feel like this is a reasonable argument.

My only criticism I guess would be that this is unfalsifiable, so for the time being it's more productive to see if there's any possibility to explain that within the observable universe.