If the A-theory of time is true, then it is (metaphysically) possible that the year 2010 have the objective property P of presentness and it is also possible that the year 2019 have P. For it is true that 2019 has P, and what is true is possible. But by the same token in 2010 it was true that 2010 has P, and so it was possible that 2010 have P. And what is metaphysically possible does not change. So even now it is possible that 2010 have P.
But a proposition is possible if and only if it is true at some possible world. Thus, if the A-theory of time true, there are possible world where 2010 has P and possible worlds where 2019 has P, and in 2010 we lived in one of the worlds where 2010 has P, while now in 2019 we instead live in a world where 2019 has P.
Consequently, given the A-theory of time, what world we inhabit continually changes.
This seems counterintuive. For now it looks like caring about what will happen is caring about what happens in some merely possible world.
