Ulla Mattfolk , dear Ulla,
The GRW model and Penrose’s gravitational collapse model are fundamentally opposed to the Everett (Many-Worlds) interpretation. Everett and his ontology are about unitarity and no collapse, with branching and decoherence creating separate worlds, if I can say. The Born rule and the probabilities thus emerge from a kind of unitary solutionthere is no nonlinear or stochastic analysis.
So the observers and measurements are internal to this universal wave function.
The GRW model rejects the unitary evolution of this wave function, introducing objective collapses that are totally independent of measurements and observations. It is there that we cannot conclude, ontologically speaking, about the interpretation or even about the ontology itself, because we can have deeper parameters to consider, or even nonlinear collapses. The GRW model breaks a kind of unitarity, so it is not an illusion or an emergent effect ,,it is real in their reasoning.
The works of Penrose and Diósi are also interesting regarding collapses; Penrose also breaks this unitarity. So there is no link between the works of Everett and these collapse models, the frameworks of Penrose–Diósi and GRW are opposed to Everett. If a person claims that a violation of Everett’s framework, by changing some mathematics or ontology inside it, is linked with collapses, it is total nonsense. It is an attempt to go further than Everett and Penrose by unifying them, but it is not possible and makes no sense.
If Penrose and GRW assume that the wave function is not complete, then they try to solve the measurement problem, while Everett tries to solve it by his interpretation. So both cannot be linked, but possibly seen as different interpretations with deeper parameters added to the wave function, to GR and QFT, since they are incomplete. It is not about outcomes, all or one , no, it is about deeper ontological and physical parameters to add.
So, if my reasoning is concrete, the works of Penrose are much more relevant, because the collapse theories can be correlated with physical structures, as in my model. Everett’s ontology has no room for this, because all is contained in the wave function. And Everett and Penrose cannot be unified together, and all attemps ontologically are non sense at my humble opinion. Best Regards
