LeandroMdO said:
I don't think any of the existing attempts at a formulation of Everett's ideas make much sense either, but that doesn't mean that a sensible, precise formulation couldn't be found in the future.
Wishful thinking is nothing scientists have to care about. Once it does not exist today, it is irrelevant.
LeandroMdO said:
There's certainly nothing logically incoherent about replacing a collapse postulate by a split postulate.
Fine, but given that a collapse postulate has a lot of problems itself, this is not really an argument in favor of splits. I think, MWI has only heavily increased quantum confusion.
LeandroMdO said:
There are many problems, such as its incompatibility with relativity and the unwarranted assumption of quantum equilibrium.
The conflict with a fundamental interpretation of relativity is unavoidable for every realistic interpretation (given Bell's theorem), so this is not a serious problem. In a weak interpretation of relativity, which allows for a hidden preferred frame, there is no problem with this.
Quantum equilibrium is not a problem given Valentini's subquantum H theorem.
LeandroMdO said:
It's not clear what happens to the wavefunction once particles are emitted/absorbed, etc. It's not clear how to implement massless vector particles.
Of course, one has to use dBB field theory. In this case, particles are nothing but phonons, with no fundamental importance. Given that for dBB field theory a lattice regularization is fine even as a fundamental theory, because relativistic symmetry is not a fundamental value, it has even less problems than usual RQFT, which has to care about the limit. Models for fermionic fields exist too.
Ok, this is off-topic here, but once you mentioned these as problems, I think I have to explain why I do not consider them as problematic. Anyway, these are problems of application to particular quantum theories. Which is, of course, a point - the straightforward construction works for canonical Hamiltonians $H= \frac12 p^2 + V(q)$ and some generalizations, but not for a completely general Hamiltonian. But relativistic field theory fits nicely into this scheme, so that this is much less problematic than it seems.
And the value of MWI depends, of course, on the available alternatives. So, it is not completely off-topic here too.