> On 11 Jun 2018, at 03:37, Bruce Kellett <[email protected]> wrote: > > From: Bruno Marchal <[email protected] <mailto:[email protected]> >>> On 8 Jun 2018, at 14:55, Bruce Kellett < >>> <mailto:[email protected]>[email protected] >>> <mailto:[email protected]>> wrote: >>> >>> From: Bruno Marchal <[email protected] <mailto:[email protected]>> >>>>> On 8 Jun 2018, at 02:32, Bruce Kellett < >>>>> <mailto:[email protected]>[email protected] >>>>> <mailto:[email protected]>> wrote: >>>>> >>>>> >>>>> The SWE does not give a preferred basis. Basing MWI on the Schrödinger >>>>> equation runs into the basis problem. Few MWI advocates actually take >>>>> this seriously. And they should. >>>> >>>> The relative proportion of histories do not depend on the choice of the >>>> base, so the base we use are chosen endemically, like the present moment >>>> for example, in the whole of physics. Obviously, we needs brain to assess >>>> our results and communicating, and some works, like sure and others, >>>> justify the indexical importance of the position base, with respect to the >>>> branch where intelligence can develop. >>> >>> What on earth are you talking about? The position basis is not well-defined >>> either. The Hilbert space corresponding to the position operator X has an >>> infinite number of possible bases -- just like any other Hilbert space. Any >>> linear vector space has an infinite number of possible bases. How do you >>> choose which one you are going to use? Talking about the relative >>> proportion of histories sounds just like the long-since refuted branch >>> counting approach to probabilities. >> >> Measure is quite different from counting. >> >> >>> And the probabilities for various outcomes most certainly depend on the >>> chosen base, as do the outcomes themselves. >> >> Well, we can use what we call in French “le peigne de Dirac”. To make that >> precise Laurent Schwartz has invented the theory of distribution. I simplify >> things here. Consider that space has been quantised, like in Loop-Gravity or >> something. Here, you do a 1004 fallacy, with respect to the goal (helping >> Grayson to have an idea of what is QM-without-collapse). > > ? > > >>>>>> In this situation, what is the role of the SWE since the wf is usually >>>>>> asserted without any reference to it? Now consider a general case where >>>>>> the wf for a system is determined using the SWE. Since the solution can >>>>>> be expanded using difference bases, say E or p, does each possible >>>>>> expansion, each implying a different possible set of measurements, imply >>>>>> a different set of worlds using the SWE? TIA, AG >>>>> >>>>> The Schrödinger equation merely gives the time evolution of the system. >>>>> To define the problem you have to specify a wave function. It is in the >>>>> expansion of this wave function in terms of a set of possible eigenvalues >>>>> that the preferred basis problem arises. So it is not really down to the >>>>> SE itself, it is a matter for the wave function. Each expansion basis >>>>> defines a set of worlds, and all bases give different worlds. >>>> >>>> That is correct, but the choice of the basis don’t change the relative >>>> “proportion of histories”. >>> >>> The choice of basis makes all the difference in the world. >> >> Everett prove the contrary, and he convinced me when I read it. I found “his >> proof” used in many books on quantum computing, although with different >> motivation. Thee result of an experiment, obviously depend of what you >> measure, but when you embed the observer in the wave, you get that what they >> find is independent of the choice of the base used to describe the >> “observer” and the “observed”. If not, the MW would already be refuted. > > In that case, MW is refuted. Clearly, what the observer finds is dependent on > the basis in which he is described.
? I disagree. The finding can depend on what the observer decide to measure, which is akin to choosing a base, but the couple “observer + that chosen base” can be studied in any base, and the same result will described in the memories of the observer. I will search Everett proofs of this, as he is the one who convinced me on this. > Or else experiments would not have definite results when described in the > laboratory from the 1p perspective. I don’t see why. > Even if you take the 'bird' view of the whole multiverse -- which is, I > agree, independent of the basis OK. At least we agree on that. > in which it is described -- the view of any observer embedded in the > multiverse is totally basis-dependent. Only in the sense that the biological brain has evolved through decoherence with respect to some base, but as you say, that process lead to the same result from the 1p perspective of those who have chosen the base, or have the base imposed through decoherence and evolution, say. If not then QM would be inconsistent, and had to different laws of physics for different observers. > That is, after all, what we mean by 'worlds' -- the view from within, or the > 1p view. An 1p view is a mental state. Usually the world is supposed to be an independent reality. > But that view depends on how you describe it: the way in which you partition > the multiverse itself. But that refers to the base chosen for the experience, not the base chosen to describe the wave corresponding to the whole observer+observed. > Only certain very special bases are robust against environmental decoherence > -- how else do you resolve the Schrödinger cat issue? Bu using the assumption that the brain is enough well defined, in say, the base position. But when we explain that we can resuscitate the cat, we typically do some base rotation for that, and this used the fact that we can (in principle of course) described the cat death and resurrection + the observer in any base. It happens that indeed, in practice, decoherence favours some base, but that does not change the fact that the multiverse, in all bases, describes exactly the same relative state of observers, despite they are related to special base. 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 post to this group, send email to [email protected] > <mailto:[email protected]>. > Visit this group at https://groups.google.com/group/everything-list > <https://groups.google.com/group/everything-list>. > For more options, visit https://groups.google.com/d/optout > <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.
