What we call anti-particles are charge and parity (CP) reversed particles that therefore behave exactly like time-reversed normal particles. But if CP reversed is equivalent to time reversed, then what is time, exactly? For instance, when we shoot pool, and hit the orderly cluster of billiard balls inside the triangle, entropy (a measure of disorder) will be most likely to increase. According to physics there is nothing that says that the reverse situation is an impossible situation, but it is just highly unlikely. The higher entropy direction of time on the other hand is much less precise to calculate to, especially when handling only a fragment of information.

Source: Forbes January 11, 2017 15:49 UTC