Chalnoth said:
In what sense? Nobody tries to consider a set of initial conditions in the MWI that includes the full wavefunction. But as long as the interactions between our world and the rest of the wavefunction are negligible, which they have to be to conform with observation, it won't effect the results anyway.I'm really not understanding your objection. This is precisely why the appearance of collapse forces us to only consider the probability distribution of results, as decoherence ensures that no single observer has access to the entire wave function.
The perspective I have is that there is one natural decomposition. The observer itself, which is defined by what hte observer knowns, AND the remainder of the universe. But the remainder of the universe does NOT mean the entire universe as we konw it in the realist sense. It means the remainder of the encodable part of the observable universe. Which means that the remainder of the universe for a proton, is probably very small! How small I can't not say at this point, but probably the expected action of a proton system at any instant of time is invariant with respect to anything happening outside the laboratory frame. so there is indeed a builting cutoff here, the cutoff is due to that it's impossible for a proton to encode information about the entire universe.
So what you admit is not posible, and seem to solve be common sense and what's "negelctable" etc, I think should be taken seriously any be accounted for in OUR human theory.
Ie. humans "theory" of say particle physics, are an external one, relative to atomic world, this is WHY the current framework did work so well, but there are missing pieces and I think the next revolution may require that we try to understand what "scaling" the theory down to subatomic observers actually does? Most certainly we will see that the interactions scale out in a way that automatically gives us unification.
But the reverse perspective is what I think is more fruitful; to start with a basal low complexity observer, and try to understand how the inference system grows as we add complexity, and see how the unified original interactions split off into the known ones.
In order to do this, we can not STICK to the external perspective (ie. classical obserer, or infinitely compelx observers, or just infinite horizons scattering matrix descriptions of clean in/out) we need to get into the domain where the setup times are so long that expectations based in uncertain theories need to be used. This is a more chaotic domain, and the expectations are interrupted before the output is collected.
Chalnoth said:
What? That's silly. The MWI reduces to the CI in the limit of complex observers. It can't predict different expectations for different observers, because CI doesn't.
CI and standard QM is not my measuring stick here. I think the problem is QM, and I my only point was that the notion of collapse, as beeing and "information update" is an essential ingredient in any theory of inference. There is no way to explain this away. Also, I simply fail to understand what the problem is with this?
An information update is not a problem, it just means that the expectation is updated.
The problem I have is that the action forms are not the result of inference in the current models, they are pulled from quatizing classical models. This is itself vere non-intrinsic. I think the information update; and actions based on expectations are key blocks to construct full expectations of actions from pure interaction historys.
Edit: Merry Xmas to everyone! :)
/Fredrik