On Thu, Jan 21, 2021 at 6:59 AM 'Brent Meeker' via Everything List < [email protected]> wrote:
> On 1/20/2021 3:58 AM, John Clark wrote: > > > Except for its simplicity the most important advantage of many worlds is > that it doesn't have to explain what "measured" means, or what a "observer" > means, or what a "choice" means because in many worlds ANY physical change > of any sort causes the Universe to split. > > > That sounds like a bug not a feature. > Exactly. And it is not true even in MWI. Does the universe split when you do a double slit experiment? Does it split into JC in the world where the photon went through the left slit and JC in the world in which the photon went through the right slit? Of course not. You have to have an interaction between the photons and the slits that is amplified by decoherence into a macroscopic record of which slit the photon went through. But then you lose the interference! So the idea that every interaction causes the universe to split is incompatible with experience. In fact, most microscopic, quantum, interactions are not amplified by decoherence into anything that could be called separate "worlds". And the idea that there are an infinity of separate worlds created every instant by the uncountable multitude of quantum interactions is just a fairy tale -- "A tale told by idiots, signifying nothing!" It is often complained that the concept of "a world" is poorly defined. I would disagree. The idea of separate worlds is clearly defined in terms of decoherence and the emergence of semi-classical states. It is only when this is added to Everett that anything sensible emerges -- anything that can make contact with experimental reality, that is. Otherwise we are led to fantastic fairy tales.... Does every C14 decay in your body instantiate a different world? Every > photon that's absorbed by that chlorophyll molecule instead of that other > molecule? As Bruno says, "World" and "Universe" become hard to define. If > you say "This universe." does it mean anything, even for a moment? But it > you can't give meaning to "This" how can you make sense of an experiment in > which "This" evolves into "That"? You need some way to talk about the > quasi-classical world, because as Bohr noted, that's where we live and > that's where science predicts things. > I agree completely. 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]. To view this discussion on the web visit https://groups.google.com/d/msgid/everything-list/CAFxXSLSD5yXW-Ry_aAAwbwTTNwPt9j00OgBhHTnio776BAfAiQ%40mail.gmail.com.
