siblingpastry, (edited ) 
I came up with a kind of thought experiment this morning, but I'm not sure if it's valid or nonsense.
Either something has always existed, or at some point, nothing existed. Those are the only two possibilities.
Nothing means literally nothing -- no matter, no space, no time, nothing.
But that's not possible -- non-existence can't exist, that's a logical contradiction.
Therefore, something has always existed.
Is that logically sound, or is it just word play?