Guess what? Sagan was right (although it took a little more than a decade). Sagan's second alternative, the oscillating universe model has been discredited by a lack of sufficient matter to cause a contraction.1 It was further discredited by the discovery of dark energy, which shows that the universe is actually expanding at an ever increasing rate.2 So, Sagan's first alternative is the one that turned out to be true. My guess is that he was betting on the second. Of course, the atheists haven't lined up to become Christians, but instead have invented their own form of metaphysics (i.e., religion). Atheists have invented the multiverse, a kind of super-universe that randomly spews out other universes (with differing physical laws) at will. The multiverse sounds scientific, but it is really philosophical wishful thinking, since there is no evidence supporting the idea. If one really thinks about it, the multiverse is impossible over the entire period of eternity (which is what atheists would propose for the age of the "invisible" part of our universe - if such a thing exists at all). The problem is that our part of the multiverse has managed to make itself completely inaccessible to contraction and future expansion. If it were possible for one part of the multiverse to become thermodynamically dead, it would be expected to be possible for others. Even if entry into such a state is extremely unlikely, eternity is a very, very long time. Certainly by now (over all eternity), the entire multiverse would have entered into one of these thermodynamically dead zones. So, one would expect the entire multiverse to have suffered thermodynamic death by now. Therefore, it makes absolutely no sense that the universe is eternal with the characteristics that we observe. We are left with Sagan's first alternative - God did it. Atheists like to say that there is no evidence for God's existence and pretend such evidence doesn't exist. However, Sagan realized that science could judge between religious claims.