The following is an excerpt from a paper writen in 2001 by Ross Amans and Dan Ragland entitled Origin of the Universe theories;
'We have seen that throughout history man has made attempts to explain how the
universe came into existence. Many ideas and conjectures have come and gone while
some remain. Throughout the ages many of these ideas have been disproved yet many
continue to undergo scientific investigation. This report has shown mainstream
theories ranging from the big bang to creation. Furthermore it has shown that due to
the existence of increasingly numerous “origin of the universe” theories it is important
that we approach each theory skeptically. We have seen several techniques that can
and should be used when evaluating these theories. It is the hope of the authors that
after you read this report you will carefully examine origin of the universe theories and
apply the techniques we have illustrated as your consider the validly, truthfulness, and
accuracy of each theory.'
In short it seems that the question is so complex even the most scholarly can't satisfactorily explain it so it leaves the individual to ponder the great question.
Full paper here;
http://web.cecs.pdx.edu/~danr/ph367u/report.pdf