With MWI, measurement is just unitary evolution entangling the observer with the system, so no collapse postulate is added.
Copenhagen plus decoherence still requires you to say the wavefunction really collapses to one outcome. MWI just treats the whole process as continuous evolution, with all branches persisting. Quentin All those moments will be lost in time, like tears in rain. (Roy Batty/Rutger Hauer) Le sam. 5 juil. 2025, 23:34, Brent Meeker <[email protected]> a écrit : > MWI doesn't assume that the experimenters choices are determined in a way > correlated with the results. MWI is commonly applied to a small system > that is isolated except for the measurement. It doesn't actually describe > the measurement anymore than Copenhagen+decoherence does. > > Brent > > On 7/5/2025 12:40 PM, Quentin Anciaux wrote: > > AG, > > The key difference is this: > > In superdeterminism, hidden variables set both the outcomes and the > measurement settings in a way that conspires to mimic quantum predictions. > > In MWI, the settings and outcomes evolve deterministically, but all > possible combinations actually happen in different branches. No single > hidden-variable script forces the observed correlations. > > So there’s no conspiracy to pick just one history, because none is singled > out. > > That's fundamentally different. > > Quentin > > All those moments will be lost in time, like tears in rain. (Roy > Batty/Rutger Hauer) > > Le sam. 5 juil. 2025, 20:46, Alan Grayson <[email protected]> a > écrit : > >> >> >> On Saturday, July 5, 2025 at 11:57:05 AM UTC-6 Quentin Anciaux wrote: >> >> AG, >> >> Nobody claims we know the exact universal wavefunction in practice. It’s >> just the statement that if quantum mechanics applies universally, there is >> some wavefunction that evolves deterministically. >> >> That’s different from superdeterminism. Superdeterminism says hidden >> variables conspire to fix outcomes and correlations. MWI doesn’t assume any >> hidden variables or conspiracies. >> >> >> *If everything evolves deterministically, then so are the settings in >> Bell experiments. So it seems there's no difference between super >> determinism and the belief that everything evolves deterministically. AG* >> >> >> >> It just says all possible outcomes happen in parallel branches. No >> loophole is needed, because nothing forces only one result to be real. >> >> Quentin >> >> All those moments will be lost in time, like tears in rain. (Roy >> Batty/Rutger Hauer) >> Le sam. 5 juil. 2025, 18:54, Alan Grayson <[email protected]> a écrit : >> >> >> >> On Saturday, July 5, 2025 at 10:32:23 AM UTC-6 Quentin Anciaux wrote: >> >> AG, >> >> You can’t write the universal wavefunction in full detail because it’s >> the total quantum state of the entire universe. >> >> In principle, it’s a giant superposition of all possible configurations >> evolving deterministically. >> >> Just because we can’t write it out explicitly doesn’t mean it’s not part >> of the formalism. Even for a modest number of entangled particles, the >> wavefunction is too big to display, but it still has a precise mathematical >> definition. >> >> Quentin >> >> >> If we have hugely limited knowlege of what the "entire universe" is, how >> can you be sure that the UWF captures the state of the universe. Seems like >> a huge stretch. You called me a prick, but the determinism you assert for >> the UWF seems virtually indistinguishable from super determinism, but >> without direct reference to Bell experiments and the loophole implied. AG >> >> >> All those moments will be lost in time, like tears in rain. (Roy >> Batty/Rutger Hauer) >> Le sam. 5 juil. 2025, 18:09, Alan Grayson <[email protected]> a écrit : >> >> >> >> On Friday, July 4, 2025 at 6:52:05 AM UTC-6 Quentin Anciaux wrote: >> >> AG, >> >> That’s exactly the point: the universal wavefunction contains all >> possible paths you might take—left, right, or none. >> >> It doesn’t “know” in advance which one you will experience; it simply >> encodes every alternative in superposition. >> >> That’s why it’s called Many Worlds. Nothing is singled out until >> decoherence makes the branches effectively independent. There will be as >> many AG as physically possible (means possible according to the >> wavefunction) >> >> Quentin >> >> >> Can you write the Universal WF? Much is claimed about it, but I've never >> seen it. AG >> >> >> >> All those moments will be lost in time, like tears in rain. (Roy >> Batty/Rutger Hauer) >> >> Le ven. 4 juil. 2025, 14:09, Alan Grayson <[email protected]> a écrit : >> >> >> >> On Friday, July 4, 2025 at 5:48:06 AM UTC-6 Quentin Anciaux wrote: >> >> AG, >> >> In MWI, whether you call it “splitting” or “differentiation” doesn’t >> really change anything essential. The universal wavefunction by definition >> contains all possible branches in superposition. >> >> What we call “worlds” are just components becoming effectively >> independent via decoherence. Nothing extra gets created, everything is >> always in the wavefunction. >> >> It’s the same formalism either way; the difference is just in how you >> choose to describe it. >> >> Quentin >> >> >> So the Universal WF contains information concerning which turn I will >> make at an intersection before I make the turn? Is this your claim what the >> MWI contains? AG >> >> >> All those moments will be lost in time, like tears in rain. (Roy >> Batty/Rutger Hauer) >> Le ven. 4 juil. 2025, 12:52, Alan Grayson <[email protected]> a écrit : >> >> >> >> On Thursday, July 3, 2025 at 7:38:03 PM UTC-6 Brent Meeker wrote: >> >> >> >> On 7/3/2025 2:51 PM, Alan Grayson wrote: >> >> I definitely understand the mathematics and logic that for light speed to >> be frame invariant, length contraction and time dilation must occur. But I >> don't see any physical model that allows that to occur, and I don't think >> Relativity provides that model. AG >> >> >> You seem to have a hang up about "models". What exactly are you asking >> for? A mechanical model of springs and masses like Faraday contrived for >> EM waves? Lorentz already derived his contraction by considering atoms as >> little particles held in place by EM forces? Isn't that "model" enough for >> you? >> >> Brent >> >> >> I'm not sure exactly what I am seeking, but logic alone leaves much to be >> desired in the context of Relativity. Lorentz's model is rarely, if ever, >> mentioned today in any discussion of Relativity, presumably because it's >> wrong, or doesn't adequately provide an explanation for length contraction, >> or possibly because logic is seen as sufficient to explain relativistic >> phenomena (when it does not IMO). As for Quentin's explanation of how many >> worlds come into being, he says they don't, but are always there, as if >> those I am supposed to think come into being at some intersection with its >> numerous different turns possible, were always implicit in the Universal >> WF, which perfectly knows the future? Quentin thinks this is a reasonable >> interpretation of the MWI, when IMO it's just untestable imagination. >> What's your opinion of this latest twist on the MWI, which is supposed to >> appeal to sober individuals? 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