We speculate that stars are moving away. They seem to merge to a single point if we reverse their motions. My question is which of the following caused the moving away.
1) The big bang is an explosion, such that they are moving away due to the explosion
2) They are accelerated away due to a force, the imaginary dark energy
3) It's due to a space expansion. That even the stars can be stationary, it gives a moving effect along with the expansion of universe. This is used to be illustrated by dots on the surface of a balloon.
So which one or more than one of the above caused the moving away of the stars.