You are asserting a false duality. Either many-worlds, OR a collapse postulate. You use evidence AGAINST a collapse as evidence FOR many worlds, which is very weak evidence. Here is a third alternative- the wavefunction is not real- merely a mathematical formalism used to calculate probability distributions (this map doesn’t have to be the territory). Here is a fourth- collapse is an approximation to a small, non-linear self-coupling in the equation that governs time evolution. Here is a fifth- evolution is governed by both the advanced and retarded Green function solution to the Schroedinger equation, and what appears to be collapse is a sort of beat-resonance between the two. Here is a sixth- there are(non-local) degrees of freedom apart from the wavefunction and ‘collapse’ occurs because our existing theory is confused about what devices actually measure. I could keep going.
Every one of the above has a huge advantage over many worlds- there is positive evidence to update in their favor. Because they accurately reproduce most of quantum mechanics, all that evidence that we can use to push us to “quantum mechanics is probably right” CAN lead us to any of the above theories.
Many worlds does NOT have Born probabilities, and so IT DOES NOT MAKE PREDICTIONS. No one knows how to use many worlds to do anything at all. So you are doing a very weird sort of Bayesian process- you use Copenhagen or one of the above theories’ predictions to update your belief to “quantum mechanics is probably right.” Now starting from this new belief, you use other facts to update to “many worlds is probably right.” Unfortunately, you didn’t notice that in switching to many worlds, all of that evidence that pointed to quantum mechanics is gone.
If you start from an agnostic prior, many world’s has no predictions to push you in the direction of “this is the right theory.”
You use evidence AGAINST a collapse as evidence FOR many worlds, which is nonsense.
That actually isn’t nonsense, even if (or rather, even though) there are not only two hypotheses. Given that collapse outright excludes many worlds, evidence against collapse is evidence in favor of many worlds. It is evidence that merely becomes weaker the more additional probability mass there is for the additional hypotheses.
You are asserting a false duality. Either many-worlds, OR a collapse postulate. You use evidence AGAINST a collapse as evidence FOR many worlds, which is very weak evidence. Here is a third alternative- the wavefunction is not real- merely a mathematical formalism used to calculate probability distributions (this map doesn’t have to be the territory). Here is a fourth- collapse is an approximation to a small, non-linear self-coupling in the equation that governs time evolution. Here is a fifth- evolution is governed by both the advanced and retarded Green function solution to the Schroedinger equation, and what appears to be collapse is a sort of beat-resonance between the two. Here is a sixth- there are(non-local) degrees of freedom apart from the wavefunction and ‘collapse’ occurs because our existing theory is confused about what devices actually measure. I could keep going.
Every one of the above has a huge advantage over many worlds- there is positive evidence to update in their favor. Because they accurately reproduce most of quantum mechanics, all that evidence that we can use to push us to “quantum mechanics is probably right” CAN lead us to any of the above theories.
Many worlds does NOT have Born probabilities, and so IT DOES NOT MAKE PREDICTIONS. No one knows how to use many worlds to do anything at all. So you are doing a very weird sort of Bayesian process- you use Copenhagen or one of the above theories’ predictions to update your belief to “quantum mechanics is probably right.” Now starting from this new belief, you use other facts to update to “many worlds is probably right.” Unfortunately, you didn’t notice that in switching to many worlds, all of that evidence that pointed to quantum mechanics is gone.
If you start from an agnostic prior, many world’s has no predictions to push you in the direction of “this is the right theory.”
That actually isn’t nonsense, even if (or rather, even though) there are not only two hypotheses. Given that collapse outright excludes many worlds, evidence against collapse is evidence in favor of many worlds. It is evidence that merely becomes weaker the more additional probability mass there is for the additional hypotheses.
I retract the overly-strong word “non-sense”, I’m not sure how to markup a strike out so I merely edited the above post.
EHeller: what if the decision-theoretic approach by Wallace et al. turns out to work? Would you consider MWI “heavily” favoured then?