On Sunday, December 2, 2018 at 1:27:05 PM UTC, Bruno Marchal wrote: > > > On 1 Dec 2018, at 17:12, [email protected] <javascript:> wrote: > > > > On Friday, November 30, 2018 at 8:53:43 AM UTC, Bruno Marchal wrote: >> >> >> On 27 Nov 2018, at 22:55, [email protected] wrote: >> >> >> >> On Tuesday, November 27, 2018 at 8:43:55 PM UTC, Philip Thrift wrote: >>> >>> >>> >>> On Tuesday, November 27, 2018 at 2:05:04 PM UTC-6, [email protected] >>> wrote: >>>> >>>> >>>> >>>> On Tuesday, November 27, 2018 at 6:49:51 PM UTC, Philip Thrift wrote: >>>>> >>>>> >>>>> >>>>> On Tuesday, November 27, 2018 at 12:17:08 PM UTC-6, >>>>> [email protected] wrote: >>>>>> >>>>>> >>>>>> >>>>>> On Tuesday, November 27, 2018 at 6:00:50 PM UTC, Philip Thrift wrote: >>>>>>> >>>>>>> >>>>>>> >>>>>>> On Tuesday, November 27, 2018 at 8:43:35 AM UTC-6, >>>>>>> [email protected] wrote: >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> On Tuesday, November 27, 2018 at 9:27:46 AM UTC, Philip Thrift >>>>>>>> wrote: >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> On Monday, November 26, 2018 at 3:43:14 PM UTC-6, >>>>>>>>> [email protected] wrote: >>>>>>>>>> >>>>>>>>>> >>>>>>>>>> *I checked the postulates in Feynman's Sums Over Histories (in >>>>>>>>>> link provided by Phil) and I see nothing related to waves, as >>>>>>>>>> expected, and >>>>>>>>>> thus nothing about collapse of anything. I would suppose the same >>>>>>>>>> applies >>>>>>>>>> to Heisenberg's Matrix Mechanics; no waves, no collapse. I suppose >>>>>>>>>> you >>>>>>>>>> could say they just produce correct probabilities, and imply nothing >>>>>>>>>> about >>>>>>>>>> relative states other than their probabilities (which wave mechanics >>>>>>>>>> does), >>>>>>>>>> but certainly nothing about consciousness. To summarize: you're >>>>>>>>>> right that >>>>>>>>>> they are "no collapse" theories, but IMO they say nothing about >>>>>>>>>> consciousness. AG* >>>>>>>>>> >>>>>>>>>>> >>>>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> In terms of the path-integral (PI) interpretation [ interesting >>>>>>>>> lecture: >>>>>>>>> https://www.perimeterinstitute.ca/videos/path-integral-interpretation-quantum-mechanics >>>>>>>>> >>>>>>>>> ], there is in effect no waves or wave function, just paths, or >>>>>>>>> histories, >>>>>>>>> in the sum-over-histories (SOH) terminology. >>>>>>>>> >>>>>>>>> There is still "decoherence" in the SOH (a single history is >>>>>>>>> ultimately "realized"), but it could be called "selection": a single >>>>>>>>> history is selected from the total ensemble of multiple and >>>>>>>>> interfering >>>>>>>>> histories. E.g. a single point on a screen is "hit" by a photon in >>>>>>>>> the >>>>>>>>> double-slit experiment. >>>>>>>>> >>>>>>>> >>>>>>>> *Does "selection" add any insight to the measurement problem; that >>>>>>>> is, why do we get what we get? And if not, what is its value? TIA, AG * >>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>> If you look at it as a "selection of the fittest" (one history >>>>>>> surviving from an ensemble of histories), then it's like a form of >>>>>>> quantum >>>>>>> Darwinism. The quantum substrate is a cruel world where all histories >>>>>>> (but >>>>>>> one) die. >>>>>>> >>>>>> >>>>>> That's not an explanation; rather, a vacuous statement of the result. >>>>>> AG >>>>>> >>>>>>> >>>>>>> >>>>> But that is a criticism of Darwinism (*natural selection*) in general. >>>>> >>>> >>>> *Ridiculous comparison IMO. Darwinism posits a changing environment and >>>> competition among species for niches. Nothing comparable in Quantum >>>> Darwinism other than all outcomes fail except for one which succeeds in >>>> each single trial, which we knew from the get-go. AG* >>>> >>>>> >>>>> *Quantum Darwinism* is a theory claiming to explain the emergence of >>>>> the classical world <https://en.wikipedia.org/wiki/Classical_physics>from >>>>> the quantum world <https://en.wikipedia.org/wiki/Quantum_mechanics> as >>>>> due to *a process of **Darwinian >>>>> <https://en.wikipedia.org/wiki/Charles_Darwin> natural selection >>>>> <https://en.wikipedia.org/wiki/Natural_selection>*; where the many >>>>> possible quantum states <https://en.wikipedia.org/wiki/Quantum_states> >>>>> are >>>>> selected against in favor of a stable pointer state >>>>> <https://en.wikipedia.org/wiki/Pointer_state>. >>>>> [ https://en.wikipedia.org/wiki/Quantum_Darwinism ] >>>>> >>>>> - pt >>>>> >>>>> >>>> >>> >>> >>> As for "competition for niches", the histories are in a sense competing. >>> Perhaps there is some conservation principle at work, so only one history >>> can win. >>> >>> I don't know. Physicists don't know. We're even. :) >>> >> >> *Darwin had a theory or proposal to explain why some changes occur and >> persist, but Quantum Darwinism doesn't, as far as I can tell. AG * >> >> >> I think that the comparison with Darwin makes sense, and in both case, >> there are many “fittest” entities. >> > > *IMO, it's a ridiculous comparison. If you affirm the MWI, then ALL > histories survive.* > > > Only the relatively consistent one, and then with very different relative > measure. If you go through the windows instead of taking the lift, you will > survive in both case, but in the normal/Gaussian worlds (measure close to > 1), you are severely injured in the first case, and not so in the second > case. > > Bruno >
*Obviously, from a one-world perspective, only one history survives for a single trial. But to even grossly approach anything describable as "Darwinian", you have to identify characteristics of histories which contribute positively or negatively wrt surviving but I don't see an inkling of that. IMO, Quantum Darwinism is at best a vacuous restatement of the measurement problemt; that we don't know why we get what we get. AG* > > > > * If you deny the MWI, there's no model whatever of "fittest" to explain > why all histories cease to exist except the one measured for a single > trial. The only thing remarkable here is that I have to explain this. AG * > > Evolution gives a tree, with many branches, and "quantum Darwinism” gives >> rise too too many locally consistent histories. None select one individual >> branche, ISTM. >> >> Bruno >> >> >> >> >>> - pt >>> >> >> -- >> 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 post to this group, send email to [email protected]. >> Visit this group at https://groups.google.com/group/everything-list. >> For more options, visit https://groups.google.com/d/optout. >> >> >> > -- > 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] <javascript:>. > To post to this group, send email to [email protected] > <javascript:>. > Visit this group at https://groups.google.com/group/everything-list. > For more options, visit https://groups.google.com/d/optout. > > > -- 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 post to this group, send email to [email protected]. Visit this group at https://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/d/optout.
