On Mon, Sep 4, 2023 at 8:14 PM Bruce Kellett <bhkellet...@gmail.com> wrote:
> On Tue, Sep 5, 2023 at 12:02 AM smitra <smi...@zonnet.nl> wrote: > >> Bell's theorem is about local hidden variables theories > > > > *It is difficult to know how to respond to this absurd idea. I have > read quite extensively on Bell's theorem and locality in quantum mechanics > and I have never met this contention before.* > Huh? How can you "*have **read quite extensively on Bell's theorem and locality*" and not know that Bell's theorem is a test to see if any theory that assumes* local realism* can account for experimental observations? Hell if you did nothing but skim the Wikipedia article on Bell's theorem you should know that because the very first sentence is: *"Bell's theorem is a term encompassing a number of closely related results in physics, all of which determine that quantum mechanics is incompatible with local hidden-variable theories"* And just a few sentences later Wikipedia says: *"Its derivation here depends upon two assumptions: first, that the underlying physical properties and exist independently of being observed or measured (sometimes called the assumption of realism); and second, that Alice's choice of action cannot influence Bob's result or vice versa (often called the assumption of locality)"* And I might add that in the duel between theories that assume local realism and quantum mechanics, experimental observation has determined that the undisputed winner was quantum mechanics. > standard QM has no explanation for the correlations Yes. That has been the standard complaint about Quantum Mechanics since the day it was invented, it can tell you what will happen with very high precision but it can't tell you why, that's why quantum interpretation has become a major industry and why very few ever felt there was a need for a Newtonian interpretation. The leading interpretation, if you could even call it an interpretation, is the one from Copenhagen which is so vague it's not even wrong, the second most popular is "Shut Up And Calculate" which works fine if you're only interested in engineering considerations, the third most popular is Many Worlds which starts from the experimentally derived *FACT* that things cannot be both local and realistic and then just follows to where Schrodinger's Equation leads. And it turns out it leads to many worlds. > >> >> * >> You seem to pretend that it's a theorem of QM, in which case one >> would start from the postulates of QM and derive bounds on correlations for >> any system described by a local Hamiltonian. That's obviously not true.* >> > > > Strange, then, that John Bell managed to do that. > As I mentioned before, in John Bell's paper where he derived his inequality he first assumed that things were both realistic and local and then just used high school algebra and logic, he didn't use any Quantum Mechanics at all to derive it, although he did show that his inequality was incompatible with Quantum Mechanics. At the time he didn't know if his inequality was true or not because it would be about two decades before it was experimentally shown to be untrue. Since nobody believed that Bell's algebra or logic was wrong the only conclusion was that the starting assumption must be incorrect and things could not be locally realistic. If it had been experimentally found that the inequality was true then that would have proven that Quantum Mechanics made a wrong prediction and so must be incomplete, but that's not the way things turned out. John K Clark See what's on my new list at Extropolis <https://groups.google.com/g/extropolis> okx > -- 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 everything-list+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/everything-list/CAJPayv0oVTMGybnMP0Fnj7pYnEx98QMzgZbyQtLHZ%3D2ScwBDww%40mail.gmail.com.
