A theory among scientists says that quantum fluctuations caused the big bang and created the universe. This seems plausible to me.
What I can't grasp yet is how a quantum fluctuation can even start without an existing universe. Aren't all physical laws created with the universe? I understand that there is no notion of "before" with respect to time, however the big bang is theorised to have occurred, but for that to occur there must have first existed something right?
I wonder also, if there was a more nothingness instead of vacuum before the universe existed and how a quantum fluctuation could have started really from ex nihilo instead of a vacuum.