Question

What happened at or before the Big Bang? Was there really an initial singularity? Does the history of the Universe go back in time forever, or only a finite amount? Of course, these questions might not make sense, but they might.

Answer 1

there was no time before the big bang, even if saying "before" in a context where time didn't exist were valid, nothing is known for certain, and theories about that are mainly speculative.

Answer 2

they do make sense for whoever is interested and thinks rationally about the mysteries of the universe. the actual big bang theory is still valid but it doesn't mean that it was the begging of all that exist since the arrival of the string theory and the discovery that has taken place about the approximate time when the phenomenon took place, it is now believed by most or some of the physicists that the big bang took place 4s after the instant 0...what then becomes the instant 0? some suggest that the 4th second was a transition in the whole process of the big bang.. but then when we come back to the question of the singularity, it has been actually suggested by Stephen Hawking that there might have been a big bang type singularity before the big bang took place, as it has been shown, a singularity is a point where space-time curvature is infinite and a huge amount of mass is compressed in an infinitely small space. the assumption for that primordial structure of the universe by Hawking was made by an allusion to the structure of a black hole which also contain a singularity.