The 2nd law of thermodynamics has its own arrow of time. Entropy always increases in the Universe. Even if I build a highly ordered system, the disorder I create in doing so outside that system outweighs the order I create. Booklearnin' for instance: the heat my brain gives off adds to the disorder of the Universe much more than the ordering of neurons in my brain subtracts.
The relationship between the thermodynamical arrow of time and the others (cosmological and psychological) is interesting. The cosmological arrow of time is in the direction of Universal expansion. As the universe expands, the number of possible configurations of matter within the universe necessarily increases. Entropy is simply a count of this number of configurations, so there is some link there.
A firmer link lies between thermodynamic and psychological time. Building memories, that is storing information about events, necessarily lowers the entropy of the brain and increases the entropy of the Universe as a whole. The reverse is something we'd probably have no control over: reducing entropy would likely yield information spontaneously rather than practically. So the psychological arrow of time is probably built on the thermodynamic one.
Thanks Bones-O, that makes sense.
I dont see why entropy would force time to move forward. In fact, I don't know of any physical law that forces time to move forward.
The way I see it, if time moves forward, then entropy increases. Also, if time moves backward, then entropy decreases.
Time doesnt appear to move backward though simply because at any given moment in time, we possess memories of previous moments in time, and lack memories of any following moments in time (Like I said before).
Overall, I believe that it is impossible to know the direction that time is flowing at any given moment in time.
Of course, the only way any of this can be true is if we assume that time exists in the first place.