> On 11 Feb 2020, at 23:26, Bruce Kellett <[email protected]> wrote: > > On Wed, Feb 12, 2020 at 3:55 AM Bruno Marchal <[email protected] > <mailto:[email protected]>> wrote: > On 10 Feb 2020, at 08:17, Bruce Kellett <[email protected] > <mailto:[email protected]>> wrote: >> >> 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. > > “Unitary evolution” is the theory, which has not an observable in any > reasonable sense of observable. > > If that is what "unitary evolution" means, then it has no bearing on physics.
The evolution is unitary (basically a change of base). The observable are just self-adjoint. It is the observation of those observable (the Eigen value of the sed-adjoint representations in some base) which lead to postulate a unitary evolution (the SWE, or Dirac, Feynman), but the evolution itself is not an observable. It is a bit the difference between Energy H and e^iHt. > > > To add a collapse is like saying that theory break down, but there no > observation indicating that it does, given that the theory explains, or is > supposed to explain, such an appearance. > > I think "explaining the appearances" is what science is all about. OK. > You claimed above that unitary evolution does not have observable. In which > case , by definition, it cannot explain experience. It relates the results of the observations, assuming some identity thesis between either brain and mind (but this does not really work, except FAPP). But the evolution itself is not an observable, it is given by a theory, abductively inferred from many experience. > > The problem I have pointed to is that unitary evolution via the Schrodinger > equation leads to data that have no relation to the oriignal state under > study. ? > So the data can give no information about the underlying quantum state, and > so your theory cannot explain experience -- because we see different results > for measurements on different quantum states. That’s not my theory, and indeed I criticize Everett on this. My theory is just Kxy = x and Sxyz = xz(yz); with mechanism at the meta-level. I have derived the quantum logic appearance from it, but also the logic of the qualia, where physics does not adresse the question, and use a non)mechanism identity thesis. Everett is in the “right” direction (with respect to Mechanism), but is still Aristotelian, and as such got all the usual mind-body difficulties. > Everett is essentially ruled out by the "no miracles" argument, since given > that the data are independent f the original state, ? > it would require a miracle for independent experiments on the same state to > give the same answers. That is not the []p versus ([]p & p) confusion, but the []p versus []p & <>t confusion. Like if physics was first person singular, when it is first person plural. It concerns multiplication of populations of machines, wearing the histoires by the contagion of the superposition (entanglement), itself given by the linearity of the tensor product. > > > What you seem to say is that QM might be wrong, but to assume a theory is > wrong to satisfy an ontological commitment is not in “the normal scientific > practice” (as you said). > > > There is no ontological commitment here. The only commitment I see in others > is that everything is unitary, and that a totally unitary theory can explain > appearances. This has been shown to be wrong. No completely unitary theory > can be consistent with our experience of the physical world. So you do commit yourself in an ontological commitment. We never experience a physical world. The idea of a physical worlds is a simplifying assumption, and not a scientific fact. > >> 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. > > On the contrary, Everett is the only one entirely consistent with unitary > evolution, > > > Have you simply ignored all the arguments that show that unitary evolution > cannot explain appearances? No, I am just not convinced when you say that the probability of each outcome is one in iterated self-multiplication. > > and that is why cosmologist refers to it, when they are confronted to the > problem that the Copenhagen have necessarily when applying QM to the whole > universe, or to just a portion we inhabit. Everett’s idea is just an idea > already defended by Newton which is that the physicists obeys to the physical > law; and Everett has just realised that most paradox get away when we apply > the SWE to the couple observed - observer. > > > Everett's idea that one should apply quantum mechanics to the whole system -- > and not make some arbitrary distinction between the classical and quantum > worlds, such that the classical is necessary to make sense of the quantum > (Bohr) -- was a valuable insight. OK. > The trouble was that the simplistic way he implemented this idea does not > work. Not completely, sure, but it is a step in the direction of getting a coherent (mechanist) theory of mind and matter, which is just wrong with Newton or QM + collapse. > > > That leads to a complicated counter-intuitive ontology, but eventually, as > Everett used Mechanism, we know that eventually any simple Turing universal > ontology will do. > > > That is even more hopeless as an account of the phenomenal world as we > experience it. Assuming some non-mechanism. With mechanism, we have no choice in the matter, and the self-reference,ce logics illustrate (at the least) that it is not hopeless, given that we extract the quantum by a theory already found by the neoplatonist, and found by all sound Turing machine in arithmetic. Bruno > > 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] > <mailto:[email protected]>. > To view this discussion on the web visit > https://groups.google.com/d/msgid/everything-list/CAFxXSLRqC6VPKEH43ndY8zc4%3D2CpDtyQprj%2BPiFzG2e1mYGTpw%40mail.gmail.com > > <https://groups.google.com/d/msgid/everything-list/CAFxXSLRqC6VPKEH43ndY8zc4%3D2CpDtyQprj%2BPiFzG2e1mYGTpw%40mail.gmail.com?utm_medium=email&utm_source=footer>. -- 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/0A7CF59C-D5DE-442E-8CFD-1E0E5CB7EA04%40ulb.ac.be.
