Big Bang: Size & Matter of Universe Explained

[thegroundhog]

TL;DR Summary

The size of the universe at the Big Bang

I've read that before the big bang all the matter in the universe was contained within an impossibly small space. How can you have matter in a smaller space than if all the space was squeezed out of an atom (or probability cloud if you want to be pedantic). Also, how does it fit it with Pauli's Exclusion Principle?

 

[PeroK]

Summary:: The size of the universe at the Big Bang

I've read that before the big bang all the matter in the universe was contained within an impossibly small space. How can you have matter in a smaller space than if all the space was squeezed out of an atom (or probability cloud if you want to be pedantic). Also, how does it fit it with Pauli's Exclusion Principle?

If the space was "impossibly" small, then by definition it couldn't have been like that!

 

[Dale]

Summary:: The size of the universe at the Big Bang

I've read that before the big bang all the matter in the universe was contained within an impossibly small space. How can you have matter in a smaller space than if all the space was squeezed out of an atom (or probability cloud if you want to be pedantic). Also, how does it fit it with Pauli's Exclusion Principle?

It is expected that at such high energy densities our current GR and QM theories break down and we need a currently unknown theory of quantum gravity.

 

[Vanadium 50]

I've read that

Where?

 

[phinds]

I've read that ...

You'll find that here on PF, as a citation, that's about as useful as saying "I overheard some guy on a bus say that ... "

 

[PeterDonis]

before the big bang all the matter in the universe was contained within an impossibly small space

Before the Big Bang, i.e., during the inflationary epoch (which is our best current model of what came before the Big Bang), there was no "matter" in the universe; all of the energy density was contained in the inflaton field (the field that drove inflation). The Big Bang happened at the end of inflation, when all of that energy density got transferred to the fields in the Standard Model that we are familiar with--quarks, leptons, and gauge bosons. This energy density was very, very high, but the universe was also very, very rapidly expanding, so this state was not the same as a state with similar energy density but confined in a small space, which is what you appear to be intuitively picturing.