Conversation so far:
Who is Andrei?
He mainly tried to explain the baryon asymmetry of the universe; in that regard.
What happen in the 70s?
Sakharov was the first scientist to introduce twin universes he called "sheets".
What else did you found interesting?
Big Bang.

Question: What was the big bang?
Self-contained rewrite: What did Andrei Sakharov have to do with the Big Bang?