# Doesn't the Big Bang negate the law of conservation of matter? [duplicate]

I was watching Hawking (2004 film) and in the movie, Hawking has a sudden insight that all the matter and energy observed in the known universe may, in fact, have sprung out from nothing (singularity) during the Big Bang event—an insight which later on goes to become the main subject of his thesis.

But this completely flies in the face of the laws of conservation of matter and energy. What gives?

In general relativity we describe the universe as a manifold equipped with a metric, and the metric is the FLRW metric that desciribes expanding spacetime. However the FLRW metric does not include the point(s) at $t = 0$ i.e. the Big Bang itself. So we cannot say that: