Mass exist because it can exist, it’s not some kind of extensile excuse for existence it’s a simple fact. We can’t postulate on why, and not even on where from, the question is “How much”. How much separates the argument, is there more mass than the universe or only what we know? Is our universe the only one ever to exist , if so it will be the last and therefore everything we ever discus about science is irrelevant , finding a unified theory is pointless, all what we discover will fade away like the expanding universe, all matter decaying into radiation.
Hawkings postulated the big bang, but did he explain why it was a only the mass that makes the universe , why that specific amount, why not a 1000 x’s more or where’s the pressure wave of energy that would have had to been pushed in front of the explosion, your saying that all the radiation – mass in the universe came to a point perfectly in a single moment.. ? What if there was more mass, more radiation or mass than the “big bang”, where is it ?
