> How do we know the big bang is not just a tiny spec in the middle of a giant ocean This is referred to as the Cosmic Landscape, or, Eternal Inflation. In ete

> How do we know the big bang is not just a tiny spec in the middle of a giant ocean This is referred to as the Cosmic Landscape, or, Eternal Inflation. In eternal inflation, the cosmological constant becomes a field in its own right, the Inflaton field, and our universe is a pocket of spacetime where that field has randomly adopted a value allowing nontrivial structure to form. https://en.wikipedia.org/wiki/Eternal_inflation https://en.wikipedia.org/wiki/Eternal_inflation The big problem is that science is based on repeatable experiments, and it's very difficult to make a theory of what happens outside the observable universe that can be tested even in principle. If a theory doesn't make falsifiable predictions, then it isn't science. Until someone comes up with a prediction that can be tested, one might as well ask, "How do we know the world wasn't created by God?" There are infinitely many things we don't know, the challenge is coming up with something we can know.