Bruce, You keep insisting that randomness "just is" and that no deeper explanation is possible, but that’s precisely the problem with the single-history view: it reduces probability to a descriptive afterthought with no fundamental meaning. You argue that in a single-history universe, we must simply accept that an event had an 80% chance of happening even if it never does. But in what sense was that probability real if only one history ever unfolds and the event never occurs?
You say that probabilities are "real enough" because they are based on prior experience. But prior experience in a single-history universe is just another way of saying, "this is what happened before." That’s not an explanation; it’s circular reasoning. You’re using past outcomes to justify probability assignments, but if probability is supposed to describe potential events, then what does it mean when a "possible" event never happens, despite being assigned a nonzero probability? In a multiverse framework, probability describes the relative frequency of events across actualized branches. It is not just an abstract expectation—it is grounded in the structure of the wavefunction itself. You dismiss the idea that measure in the wavefunction corresponds to probability, but this is not an assumption—it follows naturally from the mathematics of quantum mechanics. The Born rule is not an extra assumption in MWI; it emerges from decision theory (Deutsch-Wallace), from symmetry arguments (Zurek’s envariance), or from self-locating uncertainty. You keep demanding "proof," yet you accept the Born rule as a brute fact in your own framework without any justification beyond "that’s just how quantum mechanics works." Meanwhile, your single-history approach provides no mechanism for why probabilities match experimental results. You claim that probability "just works" without explaining why the realized history should respect the Born distribution at all. You dismiss branch weighting in MWI as unproven, yet you offer no competing explanation for why a single sequence of events should follow probabilistic predictions. Ultimately, your position amounts to: "Random events happen, probabilities just work, and there’s no deeper reason for anything." That’s not an explanation—it’s an assertion that we shouldn’t ask questions. If you’re satisfied with that, fine, but let’s not pretend it’s a superior foundation for probability. It’s just giving up on understanding why reality follows probabilistic laws in the first place. Quentin Le jeu. 6 févr. 2025, 01:09, Bruce Kellett <bhkellet...@gmail.com> a écrit : > On Thu, Feb 6, 2025 at 11:49 AM Quentin Anciaux <allco...@gmail.com> > wrote: > >> Bruce, >> >> You’re making a distinction between single-event probabilities and >> repeated trials, but you’re not addressing the core issue: in a >> single-history universe, probability is only ever descriptive, not >> explanatory. You claim that if an asteroid has an 80% chance of impact but >> doesn’t hit, then the 20% chance was simply realized. But this explanation >> is entirely retrospective—it tells us nothing about why this history, >> rather than any other, is the one that unfolded. >> > > That is the nature of random events. It seems that your real objection is > to randomness, events that have no simple mechanical explanation. That is > quantum mechanics, and you just have to get used to it. > > You say, "assuming the calculations were accurate, then there certainly >> was an 80% chance of hitting, and a 20% chance of missing." But in what >> sense was that 80% ever real? In the only history that exists, the asteroid >> never had an 80% chance of hitting—it always had a 100% chance of missing >> because that’s what happened. The probability was just a number assigned >> before the event, with no actual force in determining the outcome. >> > > I think the calculations are based on prior experience. They are real > enough, not just empty air. > > In a multiverse framework, probabilities are grounded in actual >> distributions across histories. The 80% means that in 80% of branches, the >> asteroid hits, and in 20%, it misses. This gives probability an explanatory >> role—it describes the structure of reality, not just an arbitrary number >> assigned to something that never had a chance of happening. >> > > Unfortunately, it is well known that branch counting is a failed > enterprise in quantum mechanics. So the claim that something or the other > is true in 80% of the branches is just empty rhetoric. > > You claim that MWI has no way to connect probabilities to the >> wavefunction, but that’s false. The structure of the wavefunction naturally >> assigns measure to branches, >> > > Does it now? And how does it do that? You have a well-developed ability to > make endless unevidenced assumptions and bend them to your will. Start > trying to prove some of this! > > > and those measures correspond to the squared amplitudes of the >> coefficients—the Born rule emerges from this structure. >> > > It does not without many additional assumptions. The attempts to derive > the Born rule from Everett have all failed. > > You keep asserting that probabilities in MWI are meaningless because "all >> possibilities happen," but that’s only true if you ignore the fact that >> measure matters. Not all branches are weighted equally, and the frequencies >> of outcomes reflect those weights. >> > > But you have not shown how these weights arise, or how outcomes depend on > these 'weights'. > > The issue isn’t whether we can calculate probabilities in a single-history >> world—it’s whether those probabilities have any real ontological meaning. >> You claim that in a single-history world, probabilities "just work," but >> that’s not an explanation. It’s just a way of pretending that numbers >> assigned before an event have some deeper reality when, in truth, they >> don’t. In the end, the only thing that exists is the one history that >> happens, and everything else was just an illusion of possibility. >> > > You are still looking for an 'explanation' of random events. You will look > in vain, because no such explanation can be forthcoming. > > 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 everything-list+unsubscr...@googlegroups.com. > To view this discussion visit > https://groups.google.com/d/msgid/everything-list/CAFxXSLSoueSm74SRU0nie_b%3D%3DCDft6rWboAJPMKfyNLUbHAhOA%40mail.gmail.com > <https://groups.google.com/d/msgid/everything-list/CAFxXSLSoueSm74SRU0nie_b%3D%3DCDft6rWboAJPMKfyNLUbHAhOA%40mail.gmail.com?utm_medium=email&utm_source=footer> > . > -- You received this message because you are subscribed to the Google Groups "Everything List" group. 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