(November 8, 2012 at 2:41 pm)DoubtVsFaith Wrote: If the universe has always existed, why would that mean that it would have already died out by now?Entropy. Heat evens out in time. Given infinite time (i.e. eternal existence), the heat would have evened out.
An alternative way to look at it is that something that has always existed doesn't have a beginning or an age. Mainstream science believes that the universe has a beginning (the big bang) and an age (14 billion years, or whatever it is currently). Therefore, it hasn't existed eternally.
If you say that the universe existed as a singularity eternally before the big bang, the problem is that there's no reason for the big bang. An eternally stable singularity is, well, eternally stable.
So, a cyclic universe is the best answer. As noted, though, so far no cyclic models work out.
