I believe time is explained well via the three "arrows of time", the thermodynamic, cosmological, and phsycological. Where the thermodynamic arrow of time is the direction in which chaos increases or decreases, the cosmological is the expansion/contraction of our universe, and the phsycological is the direction in which we remember the past and not the future. For life to exist (our kind of life anyway) Chaos (entropy) must increase, for the reactions needed for life.

So what about anti-particals being the mathematical equivalent of matter travelling backwards in time? Is this something we should (could?) search for an answer to, is it just one of those solutions that are meaningless, or are they exactly the same thing, and there is no distinction?

One more thing, if time dilation occurs as a result of Acceleration/Gravity what would happen if you were under absolutely no gravitational influence (flat space time)? Could this be a base or referance point for time? Or is it irrelevant because it is impossible. Or does this occur during free fall? I don't know enough about General Relativity, so they may be stupid questions.