I recently stumbled upon the concept of "reflexive self-processing", which is Chris Langan's "Reality Theory".

I am not a physicist, so if I'm wrong or someone can better explain this, or if someone wants to break out the math here, that would be great.

The idea of reflexive self-processing is that in the double slit experiment for example, which path the photon takes is calculated by taking into account the entire state of the universe when it solves the wave function.

1. isn't this already implied by the math of how we know the wave function works? are there any alternate theories that are even consistent with the evidence?

2. don't we already know that the entire state of the universe is used to calculate the behavior of particles? for example, doesn't every body produce a gravitational field which acts, with some magntitude of force, at any distance, such that in order to calculate the trajectory of a particle to the nth decimal place, you would need to know about every other body in the universe?

This is, literally, infinitely more parsimonious than the many worlds theory, which posits that an infinite number of entire universes of complexity are created at the juncture of every little physical event where multiple paths are possible. Supporting MWI because of it's simplicity was always a really horrible argument for this reason, and it seems like we do have a sensible, consistent theory in this reflexive self-processing idea, which is infinitely simpler, and therefore should be infinitely preferred by a rationalist to MWI.

why?

Because we can't actually get infinite information, but we still want to calculate things.

And in practice, we can in fact calculate things to some level of precision, using a less-than-infinite amount of information.