Is There a Difference Between Potential and Actual?

The A theory of time posits that the present is all that exists. The past and the future, in other words, don't exist. Alex's final concern deals with the B theory of time. This basically challenges the first premise of the argument or that change is real. If time is just another dimension of space and all moments of time are equally real, then maybe it's the case that change is an illusion, and it doesn't have to be explained. Ed Phaser actually discusses this very objection, and specifically the view that Einstein's relativity theory points to a B theory rather than an A Theory of time.