What powered the Big Bang? According to the first law of thermodynamics, law of conservation of energy states,

The total energy of an isolated system is constant; energy can be transformed from one form to another, but can be neither created nor destroyed.

Question is where was the energy that triggered the big bang at the first place? What are the popular hypotheses?
This is a difficult question to answer. Physics really starts after the big bang. Scientist don't know about the laws, if any, before the first instance after the big bang. The time before and during the big bang is really the province of philosophy.