I’m not an expert. My reasoning process, such as it was, was, “MWI is not generally accepted by the scientific community, but is on LW. Are there any existing scientific mysteries which could potentially be solved by examining them from the perspective of assuming MWI is true, that wouldn’t be thought of without that assumption?”. Dark matter was at the top of the list, and gravity ‘leakage’ the simplest way to describe such a possible solution.
IIRC, less than half of physicists believe in the Copenhagen interpretation, and more than half of the rest believe in MWI. At any rate, actual physicists who ascribe to MWI are not rare, and if your conjecture had anything going for it, I’m sure one of them would have thought of it. I’m under the impression that we have good theoretical reasons to believe that such interactions cannot happen. Making up statements that sound plausible given a few other assertions you’ve heard, without first understanding the technical details behind those assertions, is a poor way to generate hypotheses.
The main alternative paradigm to dark matter is modified gravity (above all, MOND, Modified Newtonian Dynamics). Modified gravity theories usually involve a change at the classical level, but it has been suggested that the galactic rotation curves, etc., might be due to some specifically quantum effect. In quantum field theory, a classical force field generated by an object is understood in terms of virtual particles emitted by that object, the quantum details can cause the field to exhibit properties different from the classical approximation, and maybe virtual gravitons do something funny when they are summed on galactic scales.
If you could explain such quantum modifications to gravity on astronomical scales, as a result of interaction between Everett worlds, then you could have something like your MWI theory of dark matter. The real problem with that, is in finding a coherent causal account of inter-world interaction.
ETA By the way, I suspect that your idea of how MWI gravitational leakage would work, uses paradigms from the wrong multiverse “level”. In string theory there is the idea of membranes in hyperspace, each with its own matter attached, and with gravity being the one force that can cross hyperspace. So what we can see in space might be just one brane, and the dark matter could be matter on other nearby branes. I suspect that you’re thinking of the MWI multiverse in similar terms—a stack of worlds, with some gravitational interaction between neighbors.
But in QM, quantum interference involves whole configurations at once. Suppose you have two entangled particles x and y, that are far apart in space. Schematically, their combined wavefunction will be x1 y1 + x2 y2 + x3 y3 + … where the x’s and y’s are different possible wavefronts for the individual particles, and xi yi is a formal product of two such individual wavefunctions. The point of nonlocality is that the combined wavefunction of the two particles is simultaneously susceptible to changes at the x end and to changes at the y end. It’s a nonlocally defined entity whose manifestation as x and y can’t be reproduced by influences that travel through the space between x and y—that’s the lesson of Bell’s theorem.
So the brane-like scenario of locally propagated gravity leaking between worlds that are neighbors in a hyperspace, doesn’t capture the nonlocality of quantum effects. What would be needed, is a type of Bohmian many-worlds theory, in which the nonlocal quantum force of Bohm (which allows Bohm to reproduce QM within a neo-classical ontology of determinism and definite trajectories), comes from some sort of nonlocal inter-world interaction. MWIers really ought to be investigating this sort of model, especially modified versions of it that approach locality.
The fact that MWI isn’t generally accepted doesn’t mean that there a sizable chunk of physicists who do accept it. I’m not even sure that you need to accept it to run the relevant equations.
This is a misconception. Many worlds has one fewer postulate then Copenhagen quantum, so there are operations you can do in Copenhagen that don’t make sense in Everettian quantum (measurement as a projection operator). Most of the physicist I know who object to many worlds object that it doesn’t have enough structure in the postulates to actually get predictions out.
Most interpretations are similar- they remove or introduce other postulates. Consistent histories, for instance, has a consistency operator that you wouldn’t use in another formulation.
This is a misconception. Many worlds has one fewer postulate then Copenhagen quantum, so there are operations you can do in Copenhagen that don’t make sense in Everettian quantum (measurement as a projection operator). Most of the physicist I know who object to many worlds object that it doesn’t have enough structure in the postulates to actually get predictions out.
The complaint is that MWI is not complete enough to give a satisfactory interpretation for the Born rule. Nevertheless, those who support MWI do believe that Born rule is essentially accurate.
Nevertheless, those who support MWI do believe that Born rule is essentially accurate.
Sure, its obvious empirically.
The question is- can you do without the measurement postulate and recover the Born rule. If you can’t, then Everett’s interpretation doesn’t work, you still have an ugly measurement postulate grafted on to the unitary theory, and you gain no elegance.
I don’t even know enough about the physics to know which equations you would have to run. However there are a lot of theoretical physics Phds.
I know one who tries to writes her thesis on two dimensional time. It’s my impression that theoretical physicists just try out various different methods of writing formula in the hope of discovery something “beautiful” or something that at least makes testable predictions.
I’m not an expert. My reasoning process, such as it was, was, “MWI is not generally accepted by the scientific community, but is on LW. Are there any existing scientific mysteries which could potentially be solved by examining them from the perspective of assuming MWI is true, that wouldn’t be thought of without that assumption?”. Dark matter was at the top of the list, and gravity ‘leakage’ the simplest way to describe such a possible solution.
IIRC, less than half of physicists believe in the Copenhagen interpretation, and more than half of the rest believe in MWI. At any rate, actual physicists who ascribe to MWI are not rare, and if your conjecture had anything going for it, I’m sure one of them would have thought of it. I’m under the impression that we have good theoretical reasons to believe that such interactions cannot happen. Making up statements that sound plausible given a few other assertions you’ve heard, without first understanding the technical details behind those assertions, is a poor way to generate hypotheses.
The main alternative paradigm to dark matter is modified gravity (above all, MOND, Modified Newtonian Dynamics). Modified gravity theories usually involve a change at the classical level, but it has been suggested that the galactic rotation curves, etc., might be due to some specifically quantum effect. In quantum field theory, a classical force field generated by an object is understood in terms of virtual particles emitted by that object, the quantum details can cause the field to exhibit properties different from the classical approximation, and maybe virtual gravitons do something funny when they are summed on galactic scales.
If you could explain such quantum modifications to gravity on astronomical scales, as a result of interaction between Everett worlds, then you could have something like your MWI theory of dark matter. The real problem with that, is in finding a coherent causal account of inter-world interaction.
ETA By the way, I suspect that your idea of how MWI gravitational leakage would work, uses paradigms from the wrong multiverse “level”. In string theory there is the idea of membranes in hyperspace, each with its own matter attached, and with gravity being the one force that can cross hyperspace. So what we can see in space might be just one brane, and the dark matter could be matter on other nearby branes. I suspect that you’re thinking of the MWI multiverse in similar terms—a stack of worlds, with some gravitational interaction between neighbors.
But in QM, quantum interference involves whole configurations at once. Suppose you have two entangled particles x and y, that are far apart in space. Schematically, their combined wavefunction will be x1 y1 + x2 y2 + x3 y3 + … where the x’s and y’s are different possible wavefronts for the individual particles, and xi yi is a formal product of two such individual wavefunctions. The point of nonlocality is that the combined wavefunction of the two particles is simultaneously susceptible to changes at the x end and to changes at the y end. It’s a nonlocally defined entity whose manifestation as x and y can’t be reproduced by influences that travel through the space between x and y—that’s the lesson of Bell’s theorem.
So the brane-like scenario of locally propagated gravity leaking between worlds that are neighbors in a hyperspace, doesn’t capture the nonlocality of quantum effects. What would be needed, is a type of Bohmian many-worlds theory, in which the nonlocal quantum force of Bohm (which allows Bohm to reproduce QM within a neo-classical ontology of determinism and definite trajectories), comes from some sort of nonlocal inter-world interaction. MWIers really ought to be investigating this sort of model, especially modified versions of it that approach locality.
The fact that MWI isn’t generally accepted doesn’t mean that there a sizable chunk of physicists who do accept it. I’m not even sure that you need to accept it to run the relevant equations.
Do you know anyone who would be willing to run through said equations?
MWI doesn’t have different equations than “mainstream” quantum mechanics. It’s just an epistemological interpretation.
This is a misconception. Many worlds has one fewer postulate then Copenhagen quantum, so there are operations you can do in Copenhagen that don’t make sense in Everettian quantum (measurement as a projection operator). Most of the physicist I know who object to many worlds object that it doesn’t have enough structure in the postulates to actually get predictions out.
Most interpretations are similar- they remove or introduce other postulates. Consistent histories, for instance, has a consistency operator that you wouldn’t use in another formulation.
The complaint is that MWI is not complete enough to give a satisfactory interpretation for the Born rule. Nevertheless, those who support MWI do believe that Born rule is essentially accurate.
Sure, its obvious empirically.
The question is- can you do without the measurement postulate and recover the Born rule. If you can’t, then Everett’s interpretation doesn’t work, you still have an ugly measurement postulate grafted on to the unitary theory, and you gain no elegance.
I don’t even know enough about the physics to know which equations you would have to run. However there are a lot of theoretical physics Phds.
I know one who tries to writes her thesis on two dimensional time. It’s my impression that theoretical physicists just try out various different methods of writing formula in the hope of discovery something “beautiful” or something that at least makes testable predictions.
MWI has no equations distinct from the standard approach.