Perhaps I’m being whooshed, but huh?
Observations are always made in the present. Scientifically speaking, anything we state about past events is actually an inference based on scientific theories and (usually) presented as the most reasonable explanation for the evidence we currently observe.
Thus, science does not “prove” in the classical sense in the same way that mathematics does.
Another way of saying it is that you can’t prove that a supernatural being didn’t invent the world on Friday with all the memories and evidence we have intact. Or that we aren’t living in a computer simulation that was turned on a moment ago. Or any other equivalent messing around with reality.
Philosophers and sophomores love debating the validity of these. Chronos was playing with that riff.
Extreme simplification: General relativity can model the early universe back to about 10-43 seconds, known as the Planck Time. At that point, the uncertainties of quantum mechanics take over and we can no longer precisely “picture” what was taking place.
Personal rambling: This may be because we just don’t have the math to do it yet.
Think of the very early days of numbers; at first, they probably had 1 and some – then 1, 2, 3 and more than 3 – etc., as people first learned to count. It is generally thought that the concept of negative numbers didn’t come about until after the invention of Zero. There were philosophical debates and doubts about the concept of Zero; “What could this ‘nothing’ actually mean?” kind of stuff.
Maybe we can compare our current state of understanding of what happened at and before the Big Bang to peoples’ understanding of negative numbers in the days before there were negative numbers and zero.