In a landscape far, far away (For a Hoosier boy, 50 years ago - Denver was QUITE foreign), walking back to Lowry Airbase after midnight on a cool late fall night morning, ruminating over the late night TY show (something about miracles at Lourdes), I found myself stating what I'd heard in school: Big Bang, Evolution, etal - I dismissed the show as fiction; a religion advertisement, a sawdust trail appeal.
Looking up at the brilliant pinpoints of light, sparkling in the high plains air, I thought of how they came to be.
Einstein's formula - E=Mc2 floated up from memory...
Knowing that the equation can be turned around to M=E/c2 I thought, "Yeah! All that MASS up there now shining down - it appeared after the tremendous energy burst of the Big Bang! The rest is history."
Almost back at the gate, confident that I'd figgered it out; an almost audible thought(?) came to me...
"Where did the ENERGY come from?"
At that time; I had no answer.
Which is another way of saying where did the mass come from? They are equivalent. Energy and mass are simply waves of nothing.
If you take it one step further to QM you will see the answer in the spontaneous pair production. In the final equation it all balances out.
The big bang, expansion of the universe, energy, matter, etc. Can all be explained from the particle anti particle spontaneous creation that occurs all the time. The energy balance stays the same though, zero. : ) Something really does come from nothing and it will go back to nothing too.