[danbmil99]

Now that I think of it, if using damped springs, the system would not be reversible. Energy is dissipated through the damping, and the system will increase in entropy and converge on a local energy minimum point.

Another way of looking at it: there are 4 states going in (0 or 1 on 2 pushers) but there are only 2 states of the 'memory' contraption, so you lose a bit on every iteration (like classical Boolean circuits)