The Big Bang theory itself has already been proved - we understand the “how?” just not the “why?”...
However, modern cosmological research by Stephen Hawking, astronomers, cosmologists and physicists indicate that blackholes actually branch off and CREATE other universes.
Our universe was created from the birth of a blackhole - every blackhole in our universe is a self-contained universe and none of them interfere with eachother. (For analogy, think of “The Tower” from Buddhism)
This does not violate any of the laws of physics, nor is entropy disturbed - blackholes give off radiation and eventually (over VERY long time scales) evaporate.
Therefore, no “god” was needed to give “birth” to our universe - we see creation happen everytime a sufficiently sized star goes supernova and when others implode to create a blackhole/universe.
To add a god in “after the fact” is a fabrication of man - the universe exists on its own. Why is there something instead of nothing? - Is like trying to think of “the void” / nothingness…