> On 10 Feb 2020, at 07:17, smitra <[email protected]> wrote: > > On 09-02-2020 19:16, 'Brent Meeker' via Everything List wrote: >> On 2/9/2020 12:48 AM, smitra 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. >> Except for every measurement ever made of a quantum variable. > > This os also explained by unitary time evolution as there observed system is > not an isolated system. >> Brent >>> 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. >>> The MWI may have some philosophical weaknesses like the derivation of the >>> Born rule but the pragmatic variant of it where you just assume the Born >>> rule is clearly superior to any other model where you're going to just >>> assume that the known laws of physics are going to be violated to get to a >>> model that to you looks more desirable from a philosophical point of view. >>>>> If the MWI (in the general sense of there existing a >>>>> multiverse rather than any details of how to derive the Born rule) >>>>> is >>>>> not correct, then that's hard to reconcile with known experimental >>>>> results. >>>> All experimental results to date are consistent with a single-world >>>> theory. There are several possibilities for such a theory, but to >>>> date, experiment does not distinguish between them. >>> Single world theories require a violation of unitary time evolution of a >>> perfectly isolated system. No experiment has ever observed this. >> Because a perfectly isolated system can't be observed. > > Observers interact locally with the observed system, so nothing would change > if the observed system plus observer were located inside a giant isolated > system. So, whatever observation is cannot funbdamentally depend on the > system not being perfectly isolated. >>>>> New physics that so far has never been observed needs to be >>>>> assumed just to get rid of the Many Worlds. Also, this new physics >>>>> should appear not at the as of yet unprobed high energies where the >>>>> known laws of physics could plausibly break down, instead it would >>>>> have >>>>> to appear at the mesoscopic or macroscopic scale where the laws of >>>>> physics are essentially fixed. >>>> Bohm's theory does not require as-yet-unobserved new physics. GRW do >>>> postulate a new physical interaction, but that is below the level of >>>> current experimental detectability. >>> Bohm theory is not equivalent to QM, it only becomes equivalent to QM if >>> one imposes a condition known as "quantum equilibrium". In general, Bohm >>> theory in a condition of quantum non-equilibrium leads to violations of the >>> Born rule. See here for details: >>> https://en.wikipedia.org/wiki/Quantum_non-equilibrium >>> Then without any experimental evidence for the additional features of Bohm >>> theory such as the signatures of quantum non-equilibrium, why would be >>> prefer it over and above a theory that doesn't make such assumptions? One >>> would have to have very strong theoretical objections against the theory. >>> In case of the Standard Model one can predict that it will break down at >>> very high energies. But I don't see why the MWI in the pragmatic sense >>> where one assumes the Born rule is so bad that it merits considering >>> alternative theories, particularly if those alternative theories make lots >>> of unverified assumptions about new physics in domains where new physics is >>> thought to be unlikely to appear. >>>> Besides, why should you assume that the Schrodinger equation is the >>>> ultimate physical law? >>> It may be false, but absent experimental evidence that it is indeed false, >>> theories that imply that it's false shouldn't get the benefit of the doubt >>> just because they imply a single world. >> Even though a single world is a well confirmed and often repeated >> empirical observation? > > It's not confirmed and repeated. One has to do an experiment that can > distinguish between the alternative theories. Unitary time evolution is > easily falsifiable. What's wrong is to claim that an experiment that on its > own would be consistent with collapse is somehow evidence for collapse if it > is also consistent with unitary time evolution when unitary time evolution > and not collapse theories are consistent with the totality of all the > experimental results.
You are right. Good answer to a common confusion. In fact there are no evidence for any number of universe, once we understand that (all models of) arithmetic satisfy the existence of all computations. Bruno > > Saibal >> Brent > > -- > 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/a97d9e53624387bc04cca104fb961aa9%40zonnet.nl. -- 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/41A90523-4A0B-48F4-9D74-2E17F8B66268%40ulb.ac.be.
