There is a long discussion of time in the thread "is time just an illusion", but since it deals with different things that I would emphasize in this problem, I guess it could be better for me to start a new thread, instead of attempting to direct the old one in the direction where I would have liked it to go. This is the question. Is our world a three dimensional world that keeps changing, or is it a four dimensional world that remains static? If we were only interested in the phenomena described by the Newton's theory, this would be mostly a useless question. The different ways of interpreting time seem to be mathematically equivalent, and the difference is purely philosophical. However, the theory of relativity seems to indicate, that the world is actually a four dimensional static object, because it is difficult to imagine how the world could be a three dimensional changing world in a spacetime where simultaneity is relative. Statistical physics instead seems to indicate, that the world is actually a three dimensional changing world, because the entropy keeps increasing. The laws of physics are invariant in time reflection, so it seems strange how an arbitrary solution to the laws of physics should be a kind of solution, where entropy increases in one direction, if the world was a static four dimensional one. So, which way is it then? I am not interested very much on mere opinions about nature of time here. The implications of relativity and statistical physics seem to be contradictory, so this matter could use some solutions.