With the discovery of dark matter and dark energy, it seems that space time may actually be substance. We know little of time and space other than how to measure it. It is very possible that our way of "accurately" measuring time could be wrong. we have yet to 100% measure accurate time other then days and years, and even there we are off.
Now could it be possible that dark matter is the physical form of space and that the pushing of dark energy on the dark matter could be what is forcing the flow of time on our universe? I tried asking this question on another forum and all i got was dismissal of the idea, no real thought process on it.