# B The Universe's creation

1. Mar 7, 2017

### babbane9

hello!
I would like to know: how did the universe create itself from nothing?
I'm a novice in a physic so maybe it's not a good question
thank you
babbane9

2. Mar 7, 2017

### Staff: Mentor

Hello and welcome to PF!

I moved your question to our Cosmology section, because although there is a lot of quantum mechanics going on at the beginning of our universe, it's actually a cosmological question. But I doubt that there is an easy answer, for nobody knows for sure. As far as I remember - and it might be wrong - our models reach back until $t= 10^{-20}\, s$, maybe $t= 10^{-40}\, s$, but not until $t=0$.

3. Mar 7, 2017

### babbane9

if I understand, there is nobody who know really how it was before the creation of the universe?
And I have an other question, why does our universe is in expansion?

4. Mar 7, 2017

5. Mar 7, 2017

### Comeback City

We also don't even know for sure that the universe came from "nothing." There are no successful models that explain what happens before the Big Bang.

6. Mar 7, 2017

### rootone

We have models which can reasonably explain the condition of the Universe a very short time after the big bang event,
There are various models that would lead to the Universe as we observe it to be now, but they all start with notion that at the earliest times it must have been extremely hot and dense.
So much so that 'matter' as we understand it today could not exist, atoms came quite a while later.
Up to a point we can study what happens at extreme density and temperature by using particle accelerators.
Beyond that point we have no way to reproduce the conditions and test them, so it's all guesswork really.
It widely believed however that there could be physics going on which simply does not occur anywhere in the Universe of the present.