Consider a deterministic physical theory on which for each t>0 there is a time-evolution operator Ut on set of all instantaneous states of the universe (i.e., global phase space), so that if u is the state of the universe at time t1, then Utu is the evolved state of the universe at t1+t. For example, Everett-style no-collapse quantum mechanics or Newtonian physics without situations like Norton's dome.
Suppose there is a first moment of time, call it time 0. Here, then, is an odd metaphysics to go with the theory. The universe fundamentally has some initial state. Then what it is for the universe to be in state v at a time t>0 is nothing else than for v to equal Utu0, where u0 is the initial state.
For a simple example, suppose that we have a simple Newtonian theory with point particles and no forces. Then what it is for a particle to be at location x at time t>0 just is for the particle to have an initial momentum p0, initial location x0 and initial mass m0 such that x=x0+(p0/m)t.
On this wacky metaphysics, later states are not caused by the initial state, but are metaphysically grounded in the initial state.
What are the merits of this kind of a weird theory? Well, it has a lot of fundamental simplicity:
- Fundamental reality is only three dimensional, and facts about later times are just mathematically derivative from the fundamental facts.
- At the fundamental level of description there is no such thing as time.
- There is no need for causation, laws of nature or nomic simplicity. Temporal evolution just is a matter of metaphysical necessity. Later states reduce to earlier ones.
This is, of course, very wacky. But if one doesn't take our intuitions about modality (say, the metaphysical possibility of miracles, which is ruled out on this account), the fundamental existence of persons, free will, and the like, and one has a deterministic theory, it is hard to avoid falling into a theory like this. Simplicity does, after all, strongly favor it.
The above formulation assumes an initial moment of time, but I think one can formulate it in terms of limiting conditions if one's deterministic theory doesn't have an initial moment.
I've noticed that for a while I've been unconsciously pursuing a curious research project. The research question is something like this: If one throws anthropocentric intuitions to the winds, what sort of interpretations of physics would one take seriously? Call this the estrangement (ostranenie) project. The point of the project is to take estranging approaches to their logical conclusion, and see where they lead. The lesson I am drawing is that when one abandons the kinds of anthropocentric approaches that Aristotelian metaphysics uses, one must go much further, and much stranger, than most people are willing to go.