Answer by Richard Muller:
You are addressing the fundamental issue of time that has not been answered either by physics or philosophers. Yes, time flows, but what does that mean?Augustine, in his Confessions (written in the 5th century), wrote “What is time? If no one asks me, I know; if I wish to explain, I do not know…. My soul yearns to know this most entangled enigma."Sir Arthur Eddington, who introduced the entropy explanation for the "arrow of time", said “The great thing about time is that it goes on….But this is an aspect of it which the physicist sometimes seems inclined to neglect.”According to biographer Robert Carnap, Einstein also bemoaned his inability to understand the flow of time. Remarkably, Einstein didn't understand the flow, but he could show that it depended not only on velocity but on gravity, and he derived equations for these changes that have been verified experimentally.Some physicists, such as Brian Greene, have concluded that since physics can't (presently) account for the flow of time, that such flow doesn't exist; it is an illusion. In my mind, that argument gets it backwards. Physics should explain reality, not deny it.Suppose time flows in fits and spurts. Could we tell? According to many popular movies, the answer is no. But in fact, we could tell by looking at distant events. We would observe their flow of time was not the same as ours. I'm soon going to publish some predictions that the flow of time is not at a constant rate, and I'll include methods to test that hypothesis.