About 15 billion's year ago there was violent exlposion called big bang theory it started a process that lead to creation of unviverse.The big bang was am explosion of an extremely hot ball of matter that was smaller than an atom.This exlosion or big bang started the process of expansion and changed which continues till today.Within min of the exlosion ,atomic particles came together to make the gases (he) helium and H which over of millions of year produced the galxies the stars and the unverse we know today ;)