Will man ever know what existed before the universe began?

Answer

The question you ask is ‘what was there before our time?’. Be careful with such questions! For you speak of time when there was no time.

Still, we may come to a better understanding of what that beginning of ‘our’ time that is the Big Bang is, and how it relates to a wider world, with other spaces and times. But even then it becomes very difficult to make concrete statements about a world of which we cannot make concrete measurements.