On Mon, Feb 10, 2020 at 5:08 PM smitra <[email protected]> wrote: > On 09-02-2020 11:37, Bruce Kellett wrote: > > On Sun, Feb 9, 2020 at 7:48 PM smitra <[email protected]> wrote: > > > >> On 08-02-2020 07:00, Bruce Kellett wrote: > >>> On Sat, Feb 8, 2020 at 4:21 PM smitra <[email protected]> wrote: > >>> > >>>> On 08-02-2020 05:19, Bruce Kellett wrote: > >>>> > >>>>> No, I am suggesting that Many-worlds is a failed theory, unable > >> to > >>>>> account for everyday experience. A stochastic single-world > >> theory > >>>> is > >>>>> perfectly able to account for what we see. > >>>>> > >>>>> Bruce > >>>> > >>>> Stochastic single word theories make predictions that violate > >> those > >>>> of > >>>> quantum mechanics. > >>> > >>> No they don't. When have violations of the quantum predictions > >> been > >>> observed? > >> > >> A single world theory must violate unitary time evolution, it has to > >> > >> assume a violation of the Schrodinger equation. But there is no > >> experimental evidence for violations of the Schrodinger equation. > >> While > >> one can make such assumptions and develop a formalism based on this, > >> the > >> issue is then that in the absence of experimental proof that the > >> Schrodinger equation is going to be violated, one should not claim > >> that > >> such a model is superior than another model that doesn't imply any > >> new > >> physics. > > > > So what. If Everettian QM doesn't work, as it has been shown to fail > > in that is does not recover normal scientific practice, then one must > > look to alternative theories. I have not advocated any particular > > theory, but a break down of unitary evolution is not such a big deal > > -- it is what we observe every day, after all. This is the heart of > > the quantum measurement problem. > > The focus on Everettian QM to argue against MWI in general is a straw > man attack.
That would not be the way most physicists would see it. They take Everettian QM as basic. Unfortunately, Everettian QM has hit a catastrophic train wreck -- it is clearly not viable as an understanding of quantum physics. The reason for this is a clear corollary of Kent's argument. Simply put, Everett takes the Schrodinger equation as basic. Acting on a general quantum state with the Schrodinger equation gives the relative states, and there can only ever be one relative state for each term in the expansion in terms of some set of basis states. The amplitudes of interest are the coefficients in this expansion. However, these coefficients or amplitudes, are just ordinary complex numbers, so are completely transparent to the SE. The set of sequences of outcomes of repeated trials (measurements on replications of the initial state) is then all n^N sequences of outcomes (labelled by 0 - n-1 for the n possible outcomes for N trials). This set of sequences is independent of the amplitudes in the original expansion of the state of interest in terms of the set of basis states. Consequently, the data one obtains from this set of experiments is one of the set of possible sequences of the integers 0 to n-1, is completely independent of the amplitudes in the original expansion. One can, therefore, gain no information about these amplitudes from the set of N trials. The Born rule is irrelevant, because the data are necessarily independent of the coefficients/amplitude. This proves that Everett's approach from the SE, where there is only one branch for each possible outcome in a single trial, cannot account for the way in which experimental results are used in practice. Given Everett, experiments cannot reveal anything at all about the original state. So Everett fails as a scientific theory. End of story. Period. Nothing more to be said. > The main issue is unitary time evolution. This is a rather > unambiguous thing that one can check in experiments. A breakdown of > unitary time evolution has never been observed. > As Brent has pointed out, unitary evolution breaks down every time we observe a particular result for a measurement (to say nothing of black holes). Your focus on unitary evolution is misplaced -- it is not universally observed. Many-worlds theory might be salvageable from the train wreck of Everett, but it is not clear how. It seems to be widely assumed that there is more than one branch for each basis state, even though that is not what Everett or the SE say. It is not clear how this could ever happen in a principled way: it certainly is not consistent with unitary evolution via the Schrodinger equation. There may be a way out of this, but none has been offered to date, and I would not hold out many prospects for success in such venture. 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/CAFxXSLQG5ugE-ZDqPRomr7VCsRi00yP8wVrXYMoRgeFgXha%3D4w%40mail.gmail.com.
