Proof that the universe is infinite

Proof that the universe is infinite - 

Consider the term 'all that exists'. Whenever we talk of "all that exists" in the case of finite things, it is always while we are considering some domain (finite) in which all that exists lies. 

Now, if we talk of a (finite) domain we should be able to talk of something which is 'not the domain'. 

Now, since the universe is all that exists, there is nothing like "not the universe". So the universe is not finite. 

Hence it is infinite.