where did the energy for the "big bang" come from? and the matter?

[Dolly Buster]

There is actually a good theory by the appropriately named J. Richard Gott of Princeton.

Two things are scientific fact despite sounding fantastical to civilians:

1. Time travel into the past is possible
   
2. Cosmic inflation can enlarge regions without them losing any density
   

So when you take these two premises it can be shown that the universe went back in time and created itself with a small piece of itself.