You'll want to start with Red Shift, then that should point you down the right path to understanding the expanding universe theories. Although the absolutely prevailing theory is the Big Bang, there could be other ways of looking at a finite, infinite universe and expansion. It could be that spacetime doesn't exist for the totality of the universe, only within it, so it's as if it's timeless to our understanding and perception. The gravitational waves pulsing through it could be what even allows spacetime to exist, for all we know. All of what I wrote is, of course, complete bullshit that I just threw out there, but the point being is that there's SO much we don't know that it allows you to find your own understanding and beliefs, whatever they might be -- it's not wrong if we don't know what's right. (It still might be stupid, just not 'wrong' ;P)