On the other hand, the future is independent of the past given the present. That’s not profound metaphysics, that’s simply how we define the state of a system: it’s everything one needs to know of the past of the system to compute its future.
There is some metaphysics involved, particularly in positing that such a “state” exists, i.e. the question of whether the universe is causal.
For example, in classical mechanics, simply the positions of every particle do not constitute the state. You need both the positions and velocities. The velocity is a function of the current configuration of the world, and also some instantaneous information (time derivative) about how its moving through time. However, that you need only the first time derivative (and not the second and further) is a fact of physics, and whether a finite description of the “state” exists, or if not even an infinite description would suffice, is a metaphysics question.
In a probabilistic model (like quantum mechanics), you’re asking for the conditional independence of the present and the past, and similar considerations hold.
There is some metaphysics involved, particularly in positing that such a “state” exists, i.e. the question of whether the universe is causal.
For example, in classical mechanics, simply the positions of every particle do not constitute the state. You need both the positions and velocities. The velocity is a function of the current configuration of the world, and also some instantaneous information (time derivative) about how its moving through time. However, that you need only the first time derivative (and not the second and further) is a fact of physics, and whether a finite description of the “state” exists, or if not even an infinite description would suffice, is a metaphysics question.
In a probabilistic model (like quantum mechanics), you’re asking for the conditional independence of the present and the past, and similar considerations hold.