On Friday, April 20, 2018 at 1:04:05 PM UTC, Lawrence Crowell wrote: > > On Friday, April 20, 2018 at 7:00:25 AM UTC-5, Bruce wrote: >> >> From: <[email protected]> >> >> >> >> *Does entanglement -- which occurs whenever two systems interact -- imply >> non-locality? AG* >> >> >> Not necessarily. If there is a common cause explanation of the >> correlation, as in classical physics where particles always have definite >> momenta, then there is no need for a non-local explanation. However, in >> quantum systems such as the singlet state of entangled spinors, then no >> common cause or hidden variable explanation is available and we have >> non-locality. >> >> Actually a similar thing happens in any collision between two quantum >> particles. If we assume an elastic collision, the outgoing particles will >> be in the form of outgoing spherical waves -- neither the individual >> momenta or directions are specified by the collision itself. So observing >> the direction and/or momentum of one particle determines the direction and >> momentum of the other remote particle. There is no common cause or hidden >> variable explanation available for this, especially if the observations are >> at space-like separations. However, as far as I know there are no Bell-like >> inequalities that are violated by the statistics in this case, so the >> non-locality is not always obvious. Interestingly, this forms the basis for >> an important measurement tool at high energy accelerators. Often the output >> from experiments will be in the form of a missing mass plot, which is >> constructed by summing the momenta of the observed particles and >> determining what is missing. This can then be the basis of a search for >> undetectable or new particles. >> >> Bruce >> > > There is an open question about this. The role of interactions is not > entirely clear. For instance, if we have a proton on proton collision that > produces as Z particle, the decay products of the Z, ultimately for > instance it might be a pair of photons, are entangled. The role of > interactions and the relationship between gauge symmetries and the quotient > group structure of entanglements is an interesting topic. > > It does have to be pointed out that in QFT with equal time commutators of > operators on spatial surfaces the nonlocality of QM is swept under the rug. > Since these nonlocal physics will only be apparent over a tiny distance > compared to the scale of the detector this loss is not considered terrible. > This eliminates nonlocality as some confusion with causal propagation, > which BTW happens with the Bohm relativistic QM. > > LC >
I thought one of the main insufficiencies with Bohm QM is that it can't be made relativistic. AG -- 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.
