Exactly the same as has been going on since the Big Bang Theory was postulated.
If on the other hand you mean "what was going on in the universe before the big bang occurred?" assuming the Big Bang theory is a correct model of the origin of the universe, .....
then the answer is: Our universe did not exist before the Big Bang. Time and Space were formed out of nothing at the moment of the Big Bang, and our Universe has been expanding ever since.
There are some theories (e.g. "M-Theory") currently being explored that suggest that "our universe" is effectively just one of a multitude of "multiverses each existing on a multidimensional "membrane" (usually called a "'brane") and one hypothesis is that two of these 'branes collided around 14 billion years ago, and the point of contact of that collision, and the energy imparted therein, is what created our universe.
-- Best wishes - Majikthise.
god creatd the the universe