Time, or rather the arrow of time, is defined within the 2nd law of thermodynamics: The future is in a higher entropy state than the present, which in turn is in a higher entopy state than the past. But when the universe, our isolated system, reaches the maximum entropy state - heat death - what happens to the arrow of time? If the entropy is at a maximum state, time doesn't flow in any direction anymore, because we've defined the future as "the place, where the entropy is higher than now." Time simply stops. What is your view on this subject? This problem clearly arises because we've defined time through the 2nd law of thermodynamics, so is our definition faulty?