like, what’s his relativistically invariant mathematical model of world splitting for multiple spacelike-separated events?
Why is this problematic in the least? World splitting isn’t a dynamical rule, but an interpretation of the state.
-- Decoherence—the process of world splitting—can be localized in spacetime. Not to a single event, but to a region, as it is a continuous process. Much like quantum leaps are not localized to single events of spacetime.
-- When information from a decoherent process reaches a new region, several things can happen:
a) the information impacts all local coherent processes equally, and produces no local decoherence (an incoherent long-wave radio pulse has a coherent effect on a BEC because it is sufficiently off-resonance that it doesn’t interact − 0 is equal to 0. Or, the radio pulse bounces off the wall, deflecting the cooling laser a tiny amount, but the laser beam remains coherent within itself)
b) the information has a small impact on local coherence (a photon impinging on a mirror causes the mirror to recoil, making it less coherent to the reflection of other photons)
c) the information alters the region in a way that causes it to decohere completely (a photon activates a chemical reaction)
-- So, your relativistically invariant interpretation notes the spacetime locales and degree of decoherence at each.
What problem is there? Really. QM goes and does its thing, and interpretations aren’t going to mess that up. If you have a relativistically invariant mathematical model of QM, then detecting world-splitting is the same process as you would apply to non-relativistic QM. That is, check whether there is a basis in which off-diagonal terms aren’t exponentially suppressed in time based on their energy difference scale. If there isn’t, it’s decoherent.
Edited to add:
One special thing to note is that this search for a basis with non-decaying off-diagonal terms will yield the same result in all reference frames, because it already spans all momenta. Even in non-relativistic QM you had to consider bases moving at all momenta. This feature is unchanged in relativistic QM.
Why is this problematic in the least? World splitting isn’t a dynamical rule, but an interpretation of the state.
-- Decoherence—the process of world splitting—can be localized in spacetime. Not to a single event, but to a region, as it is a continuous process. Much like quantum leaps are not localized to single events of spacetime.
-- When information from a decoherent process reaches a new region, several things can happen:
a) the information impacts all local coherent processes equally, and produces no local decoherence (an incoherent long-wave radio pulse has a coherent effect on a BEC because it is sufficiently off-resonance that it doesn’t interact − 0 is equal to 0. Or, the radio pulse bounces off the wall, deflecting the cooling laser a tiny amount, but the laser beam remains coherent within itself)
b) the information has a small impact on local coherence (a photon impinging on a mirror causes the mirror to recoil, making it less coherent to the reflection of other photons)
c) the information alters the region in a way that causes it to decohere completely (a photon activates a chemical reaction)
-- So, your relativistically invariant interpretation notes the spacetime locales and degree of decoherence at each.
What problem is there? Really. QM goes and does its thing, and interpretations aren’t going to mess that up. If you have a relativistically invariant mathematical model of QM, then detecting world-splitting is the same process as you would apply to non-relativistic QM. That is, check whether there is a basis in which off-diagonal terms aren’t exponentially suppressed in time based on their energy difference scale. If there isn’t, it’s decoherent.
Edited to add: One special thing to note is that this search for a basis with non-decaying off-diagonal terms will yield the same result in all reference frames, because it already spans all momenta. Even in non-relativistic QM you had to consider bases moving at all momenta. This feature is unchanged in relativistic QM.