The way i see it and this may be completely wrong that everything that could possibly happen an infinite amount of combinations. This all happens within no time and at all times. So the universe time wise does not exist and lasts forever all at once. I am sure this will be explained when our grasp of temporal physics comes out of it's infancy. I think writer of Doctor Who, Stephen Moffat said it best to explain time. It went something like "Time is like a big ball of wibbly wobbly, timey wimey." .