Ok so I previously talked about how natural physical processes P in a physical universe U can simulate other universes u as long as the time evolution operator T for U matches the time evolution operator t for u as long as the simulation state function e (which takes P to u like e P = u) are consistent; like: e T P = t u. I had a new related idea which is pretty heavily in woo territory (in a sort-of way), but if you reverse e as d you get a situation where a universe u with time evolution operator t simulates a process P with time evolution operator T such that: d t u = T P, (and d u = P). Assuming P supervenes on u (like how u supervenes on P in the U-simulates-u case), then what is U and where does it come from in this new scenario? Since the original e takes a process within U and not U itself, it is lossy wrt U, and so no function inverse exists which can reconstruct U from u; so in this new case, you have the presumption of P existing in a larger context (U) which cannot possibly supervene on u despite P entirely supervening on u. In other words, if S is a positive supervenience relationship, then S(P, U) and S(u, P) in the original scenario, and S(P, u) and S(P, U) in the new scenario

If the original scenario is ever valid in physicalism, then the analog of this in the new scenario would inevitably be idealism. Which -- again, this is in woo territory and my beliefometer here is hovering at 0% -- sort of implies an analogy between the idea of a natural simulation (which is probably likely to some degree conditional on physicalism) and multi-player / cooperative idealism between multiple independent mental universes that must agree on reality. And this maybe opens up the possibility of the belief that supervenience relations can only be connected vs can be non-connected (see https://en.wikipedia.org/wiki/Connected_relation). Or something like that... The word salad here will inevitably only get worse, so I'll stop

(actually, come to think of it, are there any arguable properties of supervenience??)