Brent, Your response is full of rhetorical flourishes, but it still doesn’t address the fundamental issue: in a single-history universe, probability describes things that never had any reality and never could have. You claim that probabilities "could have existed," but in a single history, that’s false—only one sequence ever occurs, and the others were never anything more than abstract labels assigned before the fact.
You compare probability to entropy and energy, but that analogy fails because entropy and energy can be measured within a single history. They are properties of physical systems that directly affect outcomes. Probability, in contrast, is supposed to describe potentiality—but in a single-history world, there is no real potentiality, only the one realized sequence. That means probabilities are just an abstract exercise in imagination rather than something that refers to anything in reality. You mock MWI by calling its histories "imagined," yet you rely on equally imagined possibilities in a single-history world to justify probability. The difference is that in MWI, probabilities describe real distributions of outcomes across actualized branches, whereas in a single-history world, probability is just a way to pretend that things that never happened somehow mattered. You keep bringing up poker as if probability in a single-history world is meaningful in the same way. But in a single-history framework, every game ever played follows only one sequence of outcomes, and any probability assigned to a hand was just a mental construct—it never had any effect on what actually happened. If you replayed history, there’s no guarantee any given probability assignment would be borne out, because only one history ever occurs. You say I’m "changing my story" on probabilities in MWI, but that’s just another misrepresentation. MWI does not assign probability 1 to everything—it assigns measure to branches, which correspond to relative frequencies of outcomes. That’s not an arbitrary assumption—it follows from the structure of the wavefunction itself. You dismiss that without engaging with the actual derivations (Deutsch, Wallace, Zurek), yet you accept the Born rule as a brute fact in a single-history world. Ultimately, your position amounts to: probability "just works," even though it describes things that never happened and never will. You claim I "banish probability" by actualizing everything, but in reality, it’s the single-history view that renders probability meaningless. It turns probability into a convenient fiction rather than something that reflects the structure of reality. That’s the contradiction you keep dodging. Le jeu. 6 févr. 2025, 02:43, Brent Meeker <[email protected]> a écrit : > > > > On 2/5/2025 12:10 PM, Quentin Anciaux wrote: > > Brent, > > You're arguing that probabilities in a single-world framework are as real > as those of observed events because they are derived from the same > equations. But if only one history ever happens, then unrealized > possibilities are just numbers in a calculation, not something that ever > had a chance of being real. > > But that's exactly wrong. They are in the calculation precisely because > they did have a chance of being real. You keep leaning on "only one > history happens". But the probabilities are for the individual events. > The probability of a die landing : is 1/6 . > > The theory predicts probabilities, but what actually occurs is just one > unique sequence of events. The rest—no matter how formally predicted—never > existed in any form beyond the equations. > > It existed as a possibility. Your theory implies that every event is > deterministic, which implies a simple close minded rejection of the concept > of probability. > > > You claim that this does not imply determinism, but the fact remains that > only one history ever unfolds. > > So what. Would it help that two histories unfolded? If so, just divide > your one history in half. > > Whether the process is called "random" or not, in practical terms, there > is no actual underlying ensemble of events > > First, a sequence in time is just as much an ensemble as set in space: > Whether you throw a die ten times or you throw ten dies at once. Second, > that's your misunderstanding that probability can only apply to ensembles. > I assume you've flown on an airliner. Did you consider the possibilty of > it crashing? If so then you must have considered the probability of that > occurrence, even though you could not take that flight more than once. > > —there is just the one sequence that reality plays out. That makes > probability, in this framework, purely descriptive of an imagined set of > possibilities that never had any ontological status. > > But not just "imagined". They are imagined as consistent with physical > theory and their probability can be directly calculated in some cases and > in others is estimated from statistics. You have an impoverished view of > probability, imagining it only applies to frequency within an ensemble. > But it also applies to degree of rational belief and quantum mechanical > events. > > > You say that unrealized events are "part of reality probabilistically," > but what does that even mean when they never actually happen? If an event > is assigned a 60% probability but never occurs in the only history that > exists, then in what sense was it ever a real possibility? > > Suppose it does occur, then in what sense was it's non-occurence a > possibility? You've adopted an impovoerished view in which there is no > such thing as probability and you can never flip a coin with probability > 0.5 it will come up heads. > > It was just an abstract calculation with no actual link to reality. > > You keep writing that, which is what I point to as just emotive argument. > 1) all calculation is abstract, that's what makes it universally > applicable. 2+2=4 no matter what we're counting. 2) That's simply false. > Calculated probability are linked to reality in many different ways. Some, > like die rolls and coin flips are based on physical symmetry. Others, like > quantum events are based on the height of energy barriers. Some are > inferred from statistics. They are all linked to reality...unlike > multiple-worlds whose only link is an inability to conceive of the Born > Rule outside of a frequentist interpretation. > > You keep referring to long strings of experiments as if an infinite series > of trials is guaranteed to sample all possibilities—but in a finite > universe with a unique history, that is simply not true. > > Well maybe it was before you were born, but philosophers of mathematics > used to argue that probabilities only referred to infinite sequences of > events...in much the same way you want to refer to infinite ensembles. > > > Your attempt to equate probability with other concepts like energy or > entropy fails because those are directly observable and quantifiable > properties of physical systems. > > The are no more directly observable than probability. Have you ever seen > an entropy meter? How does it work. How would you measure the energy in a > glass of water? Probability theories are tested exactly as you would any > physical theory. If the Stern-Gerlach says half the silver atoms will go > up you run thru enough silver atoms to test it. You don't say, "Oh I can't > test it because every sequence of UP and DOWN is unique. > > Probability, in a single-history framework, is not a property of the > world—it’s a mental construct we impose on it. It’s not like energy or > momentum; it’s a way of reasoning about things that will never actually > exist. > > I want to play cards with you. You must be terrible at poker. > > > MWI, on the other hand, does not set all probabilities to 1 arbitrarily. > > Now you're changing you story. Before whatever happened had probability > 1, nothing else could hav > > It gives probability a real foundation by making it about relative > frequencies across real histories. > > What's "real" about the histories. They are just *imagined* and their > number and frequency is just inferred from Born's (abstract) *probability* > calculation > > There, probabilities describe distributions of actualized outcomes, > > "Actualized" that are* never actual*. You have a way with words. > > not abstract unrealized ones. In contrast, in a single-world view, > probability is just a way of pretending that things that never existed > somehow mattered. That is the contradiction you keep glossing over. > > Because they could have existed, just like your "actualized" but not > actual outcomes. That's what probability means; it means something could > be but not necessarily be. You are trying to banish the concept of > probability by "actualizing" everything; but this fails because then there > is no meaning to the Born Rule. > > Brent > > > Le mer. 5 févr. 2025, 19:56, Brent Meeker <[email protected]> a > écrit : > >> >> >> >> On 2/4/2025 11:38 PM, Quentin Anciaux wrote: >> >> Brent, >> >> You say that unrealized possibilities are what probabilities quantify, >> but in a single-history framework, those possibilities never had any >> existence beyond the formalism. >> >> I don't know what "formalism" means in that context. When you calculate >> probabilities of events in QM the events are not "formalisms". They are >> implied by the same theories and mechanics that attributes possibility to >> the events that were observed. And on other occasions they the events that >> happen. So they are not mere formalism, their possibility and probability >> are as real as the possibility and probability of the observed events. >> >> If only one history is real, then all other possibilities were never >> actually possible in any meaningful way—they were never real candidates for >> realization, just mathematical constructs. That’s not an emotive argument; >> it’s pointing out that the entire notion of probability in such a framework >> is detached from anything real. >> >> If probability is supposed to quantify real possibilities, then in a >> world where only one history exists for all eternity, what exactly is being >> quantified? If an event with a calculated probability of 50% never happens >> in this one history, then its true probability was always 0%. >> >> That's contrary to the meaning of probability. You are assuming >> underlying determinism. You seem to conceive of probability as always >> being 1 or 0, which is the same as denying the very concept of probability >> >> Your framework claims to allow for multiple possibilities, but in >> practice, it only ever realizes one, making the rest nothing more than >> empty labels. >> >> It's not "my framework", it's the theory of probability. I think you are >> confused by the fact that probability theory has many applications. You're >> stuck on the application to ignorance in a deterministic case. But QM is >> not deterministic. The probabilities don't refer just to ignorance. Just >> because there is a single world doesn't make it a deterministic world. In >> fact MWI has more trouble representing probabilities. >> >> >> And you assert that alternatives have a "grounding in reality"—but what >> does that mean in a framework where they never actually happen? >> >> It means that the same theory that predicted the thing that happened with >> probability 0.3, also predicted the thing that didn't happen with >> probability 0.6 and this theory has been verified by finding that in long >> strings of experiments the latter happens twice as often as the former. >> >> If they had a genuine grounding, they would have to be part of reality in >> some form, even if only probabilistically. >> >> I'm telling you they are part of reality probabilistically. What do you >> mean by that phrase, if not what I've been saying? >> >> But in a single-history framework, that never happens. The probabilities >> exist only in the mind of the observer, with no external ontological >> reality. They are tools that describe nothing but a retrospective >> justification of what already happened. >> >> Energy, moment, entropy, gravity...you could say that they are all just >> tools in the mind of the physicist with no external ontological reality. >> They are just terms in our mathematics. >> >> >> The supposed "problem" in MWI—that all possibilities are >> realized—actually solves this issue. It gives probabilities a real basis in >> the structure of the universe rather than treating them as abstract >> bookkeeping. >> >> No, according to you they set all probabilities to 1. >> >> The probabilities describe real distributions across real histories >> rather than referring to things that were never real to begin with. >> >> MWI doesn't distribute across histories. It asserts that all >> possibilities occur in each event "with probability 1". That's why the >> assignment of probabilities is a problem for MWI. >> >> Brent >> >> >> The single-world view wants to use probability while simultaneously >> denying the existence of the things probability refers to. That’s not just >> emotive talk—it’s a contradiction at the foundation of the framework. >> >> Quentin >> >> Le mar. 4 févr. 2025, 23:22, Brent Meeker <[email protected]> a >> écrit : >> >>> >>> >>> >>> On 2/4/2025 11:38 AM, Quentin Anciaux wrote: >>> >>> The fundamental absurdity of single-history frameworks becomes clear >>> when we consider the reliance on theoretical constructs that, by >>> definition, never exist and never will. How can one justify using >>> mathematical tools that invoke nonexistent possibilities to explain a >>> reality where only one sequence of events is ever realized? If something >>> never existed, has no causal influence, and will never exist in any >>> possible future, how does it play any role in explaining what does exist? >>> >>> This contradiction is evident in interpretations like Bohmian mechanics, >>> where the pilot wave guides particles but remains completely unobservable >>> and uninteractive beyond that role. It’s an invisible, untouchable entity >>> that affects matter but is never affected in return—something that is >>> functionally indistinguishable from the pure abstractions of probability >>> waves in a single-world interpretation. In both cases, explanations rely on >>> constructs that have no true existence beyond their mathematical form. >>> >>> A single-history universe that leans on unrealized possibilities to >>> justify probability >>> >>> "Justify"?? Unrealized possibilities are what probabilities quantify. >>> If all possibilities were realized the wouldn't have probabilities assigned >>> to them...exactly the problem that arises in MWI. >>> >>> is making an implicit appeal to something that doesn’t and will never >>> exist. It treats the wavefunction as a real tool for calculating outcomes >>> while simultaneously denying that the alternatives it describes have any >>> grounding in reality. This is the absurdity: how can something that never >>> existed be part of an explanation for what does? >>> >>> That is just a lot of emotive talk. All the alternatives have a >>> "grounding in reality"; that's what makes the possibilities with definite >>> probabilities. >>> >>> Brent >>> >>> >>> In contrast, in a many-worlds framework, all possibilities exist and are >>> real branches of the wavefunction, providing an actual basis for >>> probability. The probabilities are not just mathematical conveniences; they >>> describe distributions of real outcomes across real histories. This removes >>> the need for metaphysical hand-waving about non-existent possibilities >>> influencing reality. >>> >>> If physics is about describing reality, then relying on things that are, >>> by construction, eternally non-existent to justify observed phenomena is >>> conceptually incoherent. It is an attempt to have it both ways—to use >>> abstract possibilities when convenient while denying their reality when >>> inconvenient. That contradiction is why single-history frameworks >>> ultimately fail to provide a satisfying foundation for probability and >>> existence itself. >>> >>> Quentin >>> >>> Le mar. 4 févr. 2025, 19:03, John Clark <[email protected]> a écrit : >>> >>>> >>>> On Tue, Feb 4, 2025 at 12:56 PM '[email protected]' via Everything >>>> List <[email protected]> wrote: >>>> >>>> *> Bohmian mechanics v Everett-DeWiit-Wheeler? * >>>>> *For Carroll, it probably means they're the same. Indistinguishable. * >>>>> >>>> >>>> *This is what I said about that about a month ago: * >>>> >>>> >>>> *Pilot Wave Theory keeps Schrodinger's Equation but needs to add >>>> another entirely new very complicated equation called the Pilot Wave >>>> Equation that contains non-local variables. When an electron enters the two >>>> slit experiment the Pilot Wave in effect produces a little arrow pointing >>>> to one of the electrons with the caption under it saying "this is the real >>>> electron, ignore all the other ones". The Pilot Wave does absolutely >>>> nothing except erase unwanted universes, it is for this reason that some >>>> have called Pilot Wave theory the Many Worlds theory in denial. * >>>> >>>> *The Pilot Wave is unique in another way, it can affect matter but >>>> matter cannot affect it, if it's real it would be the first time in the >>>> history of physics where an exception to Newton's credo that for every >>>> action there is a reaction; even after the object it is pointing to is >>>> destroyed the pilot wave continues on, although now it is pointing at >>>> nothing and has no further effect on anything in the universe. Also, nobody >>>> has ever been able to make a relativistic version of the Pilot Wave >>>> Equation.Paul dirac found a version of Schrodinger's Equation that was >>>> compatible with special relativity as early as 1927. * >>>> >>>> *John K Clark See what's on my new list at Extropolis >>>> <https://groups.google.com/g/extropolis>* >>>> 8b0 >>>> >>>> -- >>>> 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 visit >>>> https://groups.google.com/d/msgid/everything-list/CAJPayv3JL9f40jD-4qG0ry6z38ZtVysrh9RhE%2BDirJrSWzaX-w%40mail.gmail.com >>>> <https://groups.google.com/d/msgid/everything-list/CAJPayv3JL9f40jD-4qG0ry6z38ZtVysrh9RhE%2BDirJrSWzaX-w%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 visit >>> https://groups.google.com/d/msgid/everything-list/CAMW2kAopDs_qGcSEgaZJdrDUu7qgMzWgvNbE4EPFgw5pxRBQcA%40mail.gmail.com >>> <https://groups.google.com/d/msgid/everything-list/CAMW2kAopDs_qGcSEgaZJdrDUu7qgMzWgvNbE4EPFgw5pxRBQcA%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 visit >>> https://groups.google.com/d/msgid/everything-list/ab8b9168-9459-476b-9b9b-930c6763289a%40gmail.com >>> <https://groups.google.com/d/msgid/everything-list/ab8b9168-9459-476b-9b9b-930c6763289a%40gmail.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 visit >> https://groups.google.com/d/msgid/everything-list/CAMW2kAp7UGDVrCzGRnrucy%3DzYRUgOM0-o1X7Vhs1j6c5GVQygg%40mail.gmail.com >> <https://groups.google.com/d/msgid/everything-list/CAMW2kAp7UGDVrCzGRnrucy%3DzYRUgOM0-o1X7Vhs1j6c5GVQygg%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 visit >> https://groups.google.com/d/msgid/everything-list/23bf8e7f-645e-4f5e-a056-b3fc200a958c%40gmail.com >> <https://groups.google.com/d/msgid/everything-list/23bf8e7f-645e-4f5e-a056-b3fc200a958c%40gmail.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 visit > https://groups.google.com/d/msgid/everything-list/CAMW2kApBiR65jFriNpQ8mp4d2_p1k%3DWEr1QPBoS3fkDbkgTbPQ%40mail.gmail.com > <https://groups.google.com/d/msgid/everything-list/CAMW2kApBiR65jFriNpQ8mp4d2_p1k%3DWEr1QPBoS3fkDbkgTbPQ%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 visit > https://groups.google.com/d/msgid/everything-list/501201e8-75f0-4117-97b2-1c87ca805b86%40gmail.com > <https://groups.google.com/d/msgid/everything-list/501201e8-75f0-4117-97b2-1c87ca805b86%40gmail.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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