On 18/04/2016 2:53 pm, Jesse Mazer wrote:
On Sun, Apr 17, 2016 at 9:19 PM, Bruce Kellett <[email protected] <mailto:[email protected]>> wrote:On 18/04/2016 10:11 am, Jesse Mazer wrote:On Sun, Apr 17, 2016 at 7:34 PM, Bruce Kellett <[email protected] <mailto:[email protected]>> wrote: The future light cones of the observers will overlap at a time determined by their initial separation, regardless of whether they send signals to each other or not. Of course, I never meant to suggest otherwise. Imagining a central observer who receives messages about each experiment was just conceptually simpler than imagining an arbitrary system that is affected in some unspecified way by each experimenter's results along with every other part of that system's past light cone. But you certainly don't *need* to use that particular example.The issue is to find a local explanation of the correlations: appealing to some arbitrary system that is affected in some unspecified way. But my example shows that no exchange of information after the separate worlds of the two experimenters have fully decohered can ever explain the quantum correlations.Why do you think it shows that? Does "explain" mean something more than giving a mathematical model that generates the correct correlations, or is that sufficient?
Have you not understood my argument? The specified experiment results in four possible combinations of results: |+>|+'>, |+>|-'>, |->|+'>, and |->|-'>. It is relatively easy to show, either by looking at special cases, or by consideration of a repeated sequence of such experiments, that the probabilities are different for each of the four sets of results. The differences in probability depend only on the relative orientations of the measuring magnets. Conveying this angle information after the experiment has been completed, and each of the measurements has totally decohered, cannot explain these correlations.
What is required is an account of how these correlations can arise /before/ A and B speak to each other, because once they have their results in hand, it may be weeks before they actually communicate. Rubin's argument (following from Deutsch) does not achieve this.
This so-called "matching up" is pure fantasy. Who does this matching? If the central umpire is to do the matching, he has to have the power to eliminate cases that disagree with the quantum prediction. Who has that power? The laws of physics would do the matching in some well-defined mathematical way.I agree that the laws of physics will 'prevent' the formation of any worlds in which the laws of physics are violated. That is not the issue. The issue is: how do the laws of physics act in order to achieve this. Do they act locally or non-locally? If they act locally, then you are required to provided the local mechanism whereby they so act. You are not doing this at the moment.Similar to my question above, what do you mean by "mechanism" ? Do you mean something more than simply "mathematical rule that gives you the set of possible outcomes (with associated probabilities or at least probability amplitudes) at each local region of spacetime, given only the set of possible outcomes at regions in the past light cone"?
The mathematical rule that gives the differing probabilities for each outcome depending on the relative angle of the magnets is just quantum mechanics. But that is intrinsically non-local -- QM treats the separated components of the entangled pair as a single system, and the description of that entangled state does not depend on the physical separation of the components -- the components are treated as a single unit at all separations. Quantum mechanics is thus mute about any local physical mechanism whereby the information about the orientation of A's magnet is conveyed to B (or vice versa) -- quantum mechanics, unlike laboratory experiments, does not recognize the existence of any separation.
You are claiming to have a local account. But I have not yet seen it. Published attempts fail for the reasons given.
Bruce
Or would you say that such a mathematical rule would in itself be sufficient to qualify as what you mean by "mechanism"? If the latter, I already showed that you can have a mathematical rule that generates the correct correlations locally in a simple toy model involving experimenters at different locations measuring entangled particles, and I think the quote from Mark Rubin's paper at least strongly suggests he has a general mathematical model like this for arbitrary sets of particles, one where as he says, information is transferred from one location to another by a strictly "local differential equation".If you don't yet see the difference, then you need to think about it a bit more.Could you please explain what *you* think is the difference? Just because someone doesn't come to the same conclusion as you doesn't mean they have simply failed to think about it sufficiently, it may be that there is some genuine foundational disagreement, but it's hard to determine unless the argument for the differing conclusion is made explicit.Of course, what else? But the final claim is invalid: the EPR correlations are not explained in such a way in the Everett (or any other) interpretation. You either have non-locality or you have magic, unless you go for 't Hooft's version of superdeterminism. You seem to be plumping for magic.Well, as above, I don't know whether "magic" simply refers to the lack of a mathematical rule, or if you think some rules that are mathematically well-defined and generate the correct statistics in a local way would nevertheless be dismissed as too magical.
But you have given no such local rule. Bruce -- You received this message because you are subscribed to the Google Groups "Everything List" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at https://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/d/optout.
