On Tue, Dec 17, 2024 at 05:48:02PM +1100, Bruce Kellett wrote: > The proof is fairly straightforward. Informally, locality means > that if we have two disjoint points, A and B, separated by some > distance , either spacelike or timelike, then what happens at > point > A cannot affect what happens at point B, and what happens at point > B cannot affect what happens at point A. This informal notion can > be formalized by saying that the joint probability for outcomes a > at point A , and b at point B, must factorize, so that the joint > probability can be written as a product of two terms, one > dependent > only on factors local to point A, and the other dependent only on > factors local to point B: > > Pr(a,b) = p(a)*p(b), > > once all common causal factors have been taken into account. > - > > Thank you. That's what I thought. AG > > > How is non-local defined? Does it imply instantaneous, or faster than > light > transference of information? AG > > > I defined non-local above: whatever happens at A does not affect B and vice > versa. It has nothing to do with faster-than-light transfer of information. If > there was some FTL transfer between A and B, then the effect would be local. > The idea that non-locality means FTL effects is a common confusion. That idea > is totally wrong. > > Bruce
It strikes me that for Bruce, "local" means factorisability of the joint probability distribution. Which for most other people is what "locally real" means, IIUC, ie the conjunction of a measurement outcome depends only on physical things (reality) in the past light cone (locality). I'm not saying Bruce is wrong with his definitions, but he is in the minority AFAICT. BTW - I'm not claiming that MWI is a locally unreal theory, but it has been claimed by eg Deutsch. But now I see why Bruce would say that any "locally unreal" theory is "non-local", as his definitions are different. - ---------------------------------------------------------------------------- Dr Russell Standish Phone 0425 253119 (mobile) Principal, High Performance Coders [email protected] http://www.hpcoders.com.au ---------------------------------------------------------------------------- -- 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 view this discussion visit https://groups.google.com/d/msgid/everything-list/Z2IBxR2cUu3SJbNF%40zen.
