Ask Ethan: Why is the Universe electrically neutral? For some reason, the charges on the electron and proton are equal and opposite, and their numbers are equal, too. But why? Everywhere we look, on each and every one of the largest cosmic scales, it’s gravitation that dominates the structure that we form. From planets to stars, stellar systems…

https://medium.com/starts-with-a-bang/ask-ethan-why-is-the-universe-electrically-neutral-d16ebdc67de4