Among the intriguing and attractive things about cosmology, the study of the origins of the universe, is that it is still speculative to a great degeree, since we don't have nearly enough evidence to be as certain as we might like to be, and (so far) it makes little difference to how we live our lives in real time on earth. (I know, some have purported to find a hand of God behind the Big Bang, but while it's not entirely iut of line as a hypothesis, it certainly hasn't been proven.)
That's why it's fun to consider an alternative to the Big Bang being promulgated by one Roger Penrose of Oxford. He is intrigued by the possibility that the Big Bang wasn't the beginning of everything but simply one in a series of repeating cycles of growth and decay in the universe, in which the universe seems to lose energy and is ready for another Big bang to get things going again. I don't pretend to understand the intricacies of the theory (as is often the case, The Economist offers perhaps the best lay explanation), which is one of the reasons it's fun to speculate.