On Wednesday, October 26, 2022 at 12:45:17 AM UTC-5 [email protected] wrote:
> > > On 10/25/2022 4:15 PM, smitra wrote: > > On 26-10-2022 00:14, Bruce Kellett wrote: > >> On Wed, Oct 26, 2022 at 9:00 AM John Clark <[email protected]> > >> wrote: > >> > >>> On Tue, Oct 25, 2022 at 5:31 PM Bruce Kellett > >>> <[email protected]> wrote: > >>> > >>>> _> One of the main troubles with this is that the Copenhagen > >>>> Interpretation, insofar as there is any such thing, does not > >>>> entail that the wave function collapses when the result enters > >>>> consciousness. This was a mad idea put forward by Wigner, and it > >>>> was soon realized that the idea was just silly, and could never > >>>> work. So that idea has long been abandoned. Deutsch's attempted > >>>> proof involves comparison with an abandoned idea of quantum > >>>> mechanics, so it doesn't really prove anything. Besides, the whole > >>>> set-up involves assumptions about quantum computers and > >>>> consciousness that are far from obvious, and probably not even > >>>> correct._ > >>> > >>> OK, so forget about consciousness, the fact remains that If you see > >>> interference bands on Deutsch's photographic plate then that would > >>> prove a universe can split and, provided the difference between them > >>> is very small, can under the right conditions become identical again > >>> and thus merge back together. That is the key part of the multiverse > >>> idea and if it's true then there is no need to indulge in the > >>> mumbo-jumbo of Copenhagen quantum complementarity. > >> > >> That is as much mumbo-jumbo as anything in Copenhagen. For instance, > >> what determines if the difference between the worlds is small > >> 'enough'? You are using the result of no divergence between worlds to > >> conclude something about a divergence that probably never occurred. It > >> is simpler to state that no measurement was made in the Deutsch > >> set-up. Measurement, after all, involves irreversible decoherence, and > >> such cannot be 'quantum erased'. So no which-way measurement would > >> have been made in the Deutsch experiment. "Measurement" requires the > >> formation of permanent records in the environment (and many copies of > >> the result can be formed as well). > >> > > > > There is no such thing as irreversible decoherence in unitary QM. Now, > > you and Brent have invoked the expansion of the universe in past > > discussions to argue that fundamentally irreversible phenomena do > > exist. However this reasoning is flawed, because you then assume a > > semi-classical model where the expansion of the universe is described > > in a classical way. If QM is fundamental, then the entire state of the > > universe, including the space-time geometry is part of that quantum > > description. You then have a wavefunctional that assigns a complex > > amplitude to the entire state of the universe that includes al the > > fields of all particles and also the space-time geometry. > > That assumes that the long sought quantum theory of gravity will not > break unitarity. There are already proposals for this > https://arxiv.org/pdf/2201.11658.pdf > > Brent Unitarity is a group structure, and is a specific case of a groupoid. A groupoid corresponding to different cobordisms that imprint quantum number or information on a manifold. In that way the start and end of the deformation retract my differ by some topological information on this space. This is then a form of isometry inherited by the entire space. The idea that unitarity is just a special case of a more general system of diffeomorphisms or isometries is one way that quantum mechanics and gravitation may merge. LC > > > > > > > Thing is that the laws of physics are what they are. You cannot demand > > that you require measurement results to be truly permanent and that > > they therefore arise due to irreversible processes. Whether that's the > > case or not is determined by the laws of physics, not by us. > > > > Saibal > > > > > >>> So if the experiment was actually performed, what is your guess > >>> would happen, what would you place your money on, would there be > >>> interference bands on that photographic plate or would there not be? > >>> My guess is that you would see interference bands, I would not bet > >>> my life on it or even my house, but I would be willing to bet a > >>> week's salary. > >> > >> I, too, would expect to see interference bands, because no which-way > >> measurement would have been made in that set-up. > >> > >> 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/08ff4d6d-d635-45ea-a407-d201eea3eb27n%40googlegroups.com.
