I assume that current experimantal data allows to exclude only some scenarios, for example, closed Universe: Big Bang->Big Cranch We know that Universe is almost flat, but we don't know if it is closed or open. We also don't know how 'strong' the Dark Energy is: is it just a Cosmological constant or Quintessence. It gives 4 scenarios compatible with the current experimantal data: 1. Closed but expanding forever 2. Closed, ends in a finite time by Big Rip 3. Open, expanding forever 4. Open, ends by Big Rip. What is your favourite one you believe in? P.S. I know there is a special case with a flat universe, but I don't know, in case of Quintessence or Cosmological constant if it flat now is it flat forever, or curvature becomes negative when universe expands and becomes more and more dominated by the Dark Energy?