ELI5: Explain Like I'm 5

Big Bounce

A big bounce is a way of imagining how the universe works, which suggests that the universe has been going through an endless cycle of growing, shrinking, and then growing all over again. This means that the universe would go through a "big bang," where it expands extremely quickly, and then a "big crunch," where it collapses back down again. This cycle could repeat itself an infinite amount of times.