What is time? My friend and I are having an argument about the nature of time. If I understand her position correctly my friend believes that time is simply an artefact of changes in the universe, or that change is itself synonymous with time. This seems to be a commonly accepted position, however I replied that if two spheres were moving in space in parallel to one another but one sphere was moving faster than the other then that would mean that that sphere would traverse a greater distance in less time but with an equal degree of change in the universe. Thus time and change are two separate things. I guess the physics of that claim are debatable but I suspect that it demonstrates something true in a way that is a priori irrespective of the physics because even if there were a physical difference in the amount of forces which change it would be hard to see how those imperceptible forces would contribute to a difference in how we perceive the time effect of those different objects. What do you philosophers think? Which of us is closer to the truth or is the nature of time better answered by physicists than by a priori speculation?