We can track the progress of the universe all the way back to only moments after the big bang, but no further. So we’ll never actually be able to see what happened at the instant of the big bang. We may be able to determine if the the big bang was a singularity (with nothing before), or just a severe “pinching” of the universe (with stuff happening before). However, for all practical purposes the universe is about 15 billion years old (give or take). If there was anything around before then, it got messed up good by the big bang.