The other posts describe the answer to your question. Another way you could pose the questions is: is it possible to divide time into infinitely small segments? I think I have read that time and space are granular in the same way that energy is. Otherwise, quantum fluctuations result in...
In a "Briefer History of Time" Hawking says what everybody else does: that the laws of physics do not indicate a preference for time running forward or backward. He says that the forward direction may be required somehow by the increase of entropy from the highly ordered state of the...