Hmm, I don’t follow your argument re the Cavendish experiment. The original one was performed with fairly heavy lead balls.
I’m willing to state outright that MWI relies on the existence of gravity also being quantum outright, not semiclassical in nature. This does not seem like much of a concession to me.
That semiclassical gravity does not work in the weak-filed regime is a fairly strong statement. Widely accepted models like the Hawking and Unruh radiation are done in that regime.
A rigorous argument that semiclassical gravity is incompatible with MWI would probably be worth publishing.
Even if you start with an initial state where there is a well defined Cavendish-experimenter-man (which if you’re going with no objective collapse is a rather peculiar initial state) MWI has him all over the room, performing experiments at different times, with the weights at different displacements. They’d be pulling one way and the other, and his readings would make no sense whatsoever.
Semiclassical gravity is a perfectly fine approximation, but to say it’s real? Heh.
I meant something more limited than this, like a small cantilever in an unstable equilibrium getting entangled with a particle which may or may not push it over the edge with 50% probability, and measuring its gravitational force on some detector.
Oh. Well, then, it’s no longer ‘obviously false’ as far as that goes (i.e. we haven’t done that experiment but I would be shocked at anything but one particular outcome), but the whole point of MWI is to not restrain QM to applying to the tiny. Unless something happens between there and macro to get rid of those other branches, stuff gonna break hard. So, yeah. As an approximation, go ahead, but don’t push it. And don’t try to use an approximation in arguments over ontology.
Hmm, I don’t follow your argument re the Cavendish experiment. The original one was performed with fairly heavy lead balls.
That semiclassical gravity does not work in the weak-filed regime is a fairly strong statement. Widely accepted models like the Hawking and Unruh radiation are done in that regime.
A rigorous argument that semiclassical gravity is incompatible with MWI would probably be worth publishing.
Nawww, how could that be publishable?
Even if you start with an initial state where there is a well defined Cavendish-experimenter-man (which if you’re going with no objective collapse is a rather peculiar initial state) MWI has him all over the room, performing experiments at different times, with the weights at different displacements. They’d be pulling one way and the other, and his readings would make no sense whatsoever.
Semiclassical gravity is a perfectly fine approximation, but to say it’s real? Heh.
I meant something more limited than this, like a small cantilever in an unstable equilibrium getting entangled with a particle which may or may not push it over the edge with 50% probability, and measuring its gravitational force on some detector.
Oh. Well, then, it’s no longer ‘obviously false’ as far as that goes (i.e. we haven’t done that experiment but I would be shocked at anything but one particular outcome), but the whole point of MWI is to not restrain QM to applying to the tiny. Unless something happens between there and macro to get rid of those other branches, stuff gonna break hard. So, yeah. As an approximation, go ahead, but don’t push it. And don’t try to use an approximation in arguments over ontology.
Sorry, I forgot for a moment that the notion was designed to be untestable. Never mind.
What? All you need to do is falsify QM, and MWI is dead dead DEAD.
As I said, you identify QM with MWI. This is not the only option.
What is it, then?
Either the branches we don’t experience exist, or they don’t.
If they don’t, then what made us exist and them not?
Not this discussion again. Disengaging.
It’s never this discussion, since it never gets discussed, but OK!