On Sun, Oct 6, 2019 at 10:33 PM Philip Thrift <[email protected]> wrote:
> On Sunday, October 6, 2019 at 6:03:29 AM UTC-5, Bruce wrote: >> >> >> And I have, on many occasions, shown that these approaches are not >> successful in eliminating the non-locality. Price and Tipler, indeed, just >> reproduce the standard non-local quantum account. If you are so convinced >> that these papers give a fully local explanation for the violation of the >> Bell inequalities, then reproduce the argument here so that we can agree on >> what, exactly, we are talking about. >> >> Bruce >> > > EPR and Many Worlds has been "worked out" many rimes before, but hasn't > really changed the world. > > http://settheory.net/many-worlds > > The idea is to dismiss the reality of the collapse, consider that the > deterministic evolution without collapse is all what happens, and admit a > persisting coexistence of all possibilities in parallel worlds, in each of > which things would only "look as if" the collapse happened. > > *The Many-worlds interpretation of the EPR paradox* > > Imagine a pair of entangled particles, that will be simultaneously > measured, each in a specific way, by Alice and Bob, such that for each, the > probability is 1/2 to find heads or tails, but globally there is only 10% > probability that they get the same result. > > So, Alice seeing her measurement result evolves into a superposition (or > split) between 2 mental states : Alice-head and Alice-tail, with the same > weight of 1/2 each. > > In the same way, Bob evolves into a superposition (or splits) into 2 > copies : Bob-head and Bob-tail, each with weight 1/2. > Then, Alice and Bob meet again. > > Alice-head sees Bob in a superposition of states, composed of 10% of > Bob-head and 90% of Bob-tail, > Alice-tail sees Bob in its remaining states, that is a combination of 90% > of Bob-head with 10% of Bob-tail. > All very well, but what is the mechanism for this to happen -- what is the joint wave function when they meet that has these weights for the relevant branches? How does unitary evolution from the initial state lead to this particular wave function with these probabilities? And what determines the probabilities? There is no actual causal explanation here. > Bob-head sees Alice as in a superposition of states, composed of 10% of > Alice-head and 90% of Alice-tail > Bob-tail sees Alice in a combination of 90% of Alice-head with 10% of > Alice-tail. > > Then, Alice tells Bob her measurement result. > For her this changes essentially nothing : > When Alice-head says "head" she sees Bob as deterministically evolving > from the mixture (10% of Bob-head + 90% of Bob-tail), into the mixture (10% > of Bob-head-head + 90% of Bob-tail-head) ; and similarly for Alice-tail who > says "Tail". > Interesting. What is the interaction that occurs when Alice says "head" that causes Bob to deterministically evolve in this way? > But bob's experience here is a bit different : > Bob-head sees Alice's state collapsing from the undetermined state of (10% > Alice-head + 90% Alice-tail), into either Alice-head (with 10% probability) > or Alice-tail (with 90% probability); this splits himself between > Bob-head-head and Bob-head-tail with these probabilities. > So there is a collapse after all? > Meanwhile, Bob-tail sees Alice's state collapsing from the undetermined > state of (90% Alice-head + 10% Alice-tail) as he saw her, into either > Alice-head (with 90% probability) or Alice-tail (with 10% probability). > There is no dynamics for this in the Schrodinger equation. Since there is no interaction at the intersection of the forward light cones (it is not necessary for Alice and Bob to actually meet; we could have a third party collect the data), the probabilities for the four possible worlds have to have been set while Alice and Bob were still at space-like separations -- in other words, at the time of their individual measurements. Or else there is no explanation for the 10% and 90% probabilities mentioned in this account. 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 view this discussion on the web visit https://groups.google.com/d/msgid/everything-list/CAFxXSLRnGY2SfAjuxY6g%3DUbLxHG-EnWaJqixRf8C-Jx%3DE%2Bt7WQ%40mail.gmail.com.
