> On 22 Dec 2019, at 07:52, Bruce Kellett <[email protected]> wrote: > > On Wed, Dec 18, 2019 at 6:32 AM 'Brent Meeker' via Everything List > <[email protected] <mailto:[email protected]>> > wrote: > On 12/17/2019 3:54 AM, John Clark wrote: >> >> OK, but the very definition of "The Helsinki Man" is the man who is >> experiencing Helsinki right now today. Or at least that's the definition on >> Mondays Wednesdays and Fridays, but on other days of the week the definition >> is the man who REMEMBERS experiencing Helsinki today, and on those days the >> Helsinki Man would be a fool to expect that the Helsinki Man would >> experience one and only one thing tomorrow. > > I did use proper nouns. So what is John Clark's answer to the question what > did the Helsinki man expect regarding his future just before he pushed the > button? My guess would be that he expected to experience being in either > Moscow or in Washington, just as if H-man were going to be anesthetized and > flown to one or the other city. > > Philip Ball, in his recent book "Beyond Weird" (2018) addresses a similar > issue of personal duplication in a quantum many-worlds setting. He remains > unconvinced by the rhetoric.... > > "Imagine that our observer, Alice, is playing a quantum version of a simple > coin-toss gambling game ... that hinges on measurement of the spin state of > an atom prepared in a 50:50 superposition of 'up' and 'down'. If the > measurement elicits 'up', she doubles her money. If it's 'down', she loses it > all. > "If the MWI is correct, the game seems pointless -- for Alice will, with > certainty, both win and lose.
That is true for an external observer, but false for Alice, or anyone entangled with Alice. From her point of view she can expect to clearly win, or clearly lose, but not both at once, for the same reason that I can expect the Schroedinger cat to be found Alive or dead, but never both at once, from the point of view of anyone interacting with the cat. Philipp Ball miss the distinction between 1p and 3p. Everett did not. He used the term “subjective” for 1p. > And there's no point in her saying 'Yes, but which world will I end up in?' > Both of the two Alices that exist once the measurement is made are in some > sense present in the 'her' before the toss. And both are still present after the toss, but they have differentiated. > "But now let's do the sleeping trick. Alice is put to sleep before the > measurement is made, knowing she will be wheeled into one of two identical > rooms depending on the outcome. Both rooms contain a chest -- but inside one > is twice her stake, while the other is empty. When she wakes, she has no way > of telling, without opening the chest, whether it contains the winning money. > But she can then meaningfully say that there is a 50% probability that it > does. If today someone can predict with certainty that tomorrow he will be uncertain of the outcome of an experience, then today that person is incertain of the outcome of that future experience. You can do the same with the WM-duplication, assuming the reconstruction box are completely identical and give no clue on their localisation. After the cut and copy, the candidate will not been able to say in which city he is before opening the box. But that makes the H-guy as well uncertain of the outcome, given that we agree that both copies are dignified survivors of the experience. > What's more, she can say 'before the experiment' that when she wakes, these > will be the odds deduced by her awakened self as she contemplates the > still-closed chest. Is 'that' a meaningful concept of probability? Yes. Why not? > "The notion here is that quantum events that occur for certain in the MWI can > still elicit probabalistic beliefs in observers simply because of their > ignorance of which branch they are on. Like with Mechanism in all arithmetical models of arithmetic. > "But it won't work. Suppose Alice says, with scrupulous care, 'The experience > I will have is that I will wake up in a room containing a chest that has a > 100% chance of being empty.' The Everettian must accept this statement as a > true and rational belief too, for the initial 'I' here must apply to both > Alices in the future. Assuming that Mechanism is false, I can imagine some circumvolved way to make sense of this. With Mechanism, only the prediction which are verified by both copies can be said correct. Obviously if she predicts that the chest will be empty, we know that the one with a non empty desk will refute the prediction, and, in the finite duplication case, that is enough to say that the prediction was false. After a self-duplication (made at the right level) the first person experiences diverge, and indeed, that is why Alice cannot make a certain specific prediction about what will be in the chest or not. > "In other words, Alice-Before can't use quantum mechanics to predict what > will happen to her in a way that can be articulated -- because there is no > logical way to talk about 'her' at any moment except the conscious present > (which, in a frantically splitting universe, doesn't exist). That is not valid, as Mechanism illustrates clearly, once of course we get the 1p/3p distinction. > Because it is logically impossible to connect the perceptions of Alice-Before > to Alice-After, 'Alice' has disappeared. You can't invoke an 'observer' to > make your argument when you have denied pronouns any continuity." (Beyond > Weird, pp 301-2) It can be a continuous split. (It his provably a continuous split in the topology of the logic associated with knowledge, as opposed to 3p beliefs). > > Ball concludes, "What the MWI really denies is the existence of facts at all. Not at all. I would say that it is Ball who denies the first person experience in a many personal histories setting, like with the universal waves, or the universal computations. > It replaces them with experience of pseudo-facts (we 'think' that this > happened, even though that happened too). In so doing, it eliminates any > coherent notion of what we can experience, or have experienced, or are > experiencing right now. We might reasonably wonder if there is any value -- > any meaning -- in what remains, and whether the sacrifice has been worth it.” It is the probabilities on the relative outcome (first person, or first person plural) which counts. The fact that you will survive no matter what when jumping out of the windows, is not relevant if the goal is, not to survive, but to keep some quality of life. By using the lift, you survive in good shape, which has a negligible probability when going through the windows. 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/CAFxXSLS32zvGrcc_1%3Dd973oBzN0iXonnXn5suEP3RFPf7hSjHw%40mail.gmail.com > > <https://groups.google.com/d/msgid/everything-list/CAFxXSLS32zvGrcc_1%3Dd973oBzN0iXonnXn5suEP3RFPf7hSjHw%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/637A0510-0DA9-48A6-B931-AEE9C0950E1D%40ulb.ac.be.
