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The Zen anti-interpretation of quantum mechanics (2021)

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Re: The Zen anti-interpretation of quantum mechanics (2021)

#111

Post by kovezd »

scottmsul wrote: post #43

Something that's always bothered me about many-worlds is that it states the number of worlds should always be increasing exponentially. Which means from an anthropic point of view, the most likely time to be born is the last ever human, with insanely exponential odds. But many people have been born in my lifetime, ergo many-worlds seems unlikely.

I've been curious to learn theories where only a subset of scenarios beget alternative world, and many of these ultimately merge into more probable branches of reality. Keeping the total number of worlds growing at less than O(n*2) with respect to time.

Re: The Zen anti-interpretation of quantum mechanics (2021)

#112

Post by ravel-bar-foo »

scottmsul wrote: post #43

Something that's always bothered me about many-worlds is that it states the number of worlds should always be increasing exponentially. Which means from an anthropic point of view, the most likely time to be born is the last ever human, with insanely exponential odds. But many people have been born in my lifetime, ergo many-worlds seems unlikely.

This reasoning is fallacious. Assuming the theory, the number of worlds in which humanity doesn't exist or already died off also increases exponentially, as does the number of worlds where you are not the last human. These exponential terms balance out to the result that many worlds cannot affect the probability of conditional events at all, once you take account for the anthropic bias.

Re: The Zen anti-interpretation of quantum mechanics (2021)

#113

Post by layer8 »

shadowgovt wrote: post #101
lmm wrote: post #84

Earlier quoted context omitted.

> It’s an interpretation because we don’t have any empirical evidence for the other worlds. Science requires evidence, math alone isn’t enough. By that logic assuming that distant parts of the universe still exist is metaphysics (since it would take many years for any information from there to reach us), yet few people feel the need to call it such.

That's quite correct though. Assuming distant parts of the universe still exist is metaphysics; it's relying on Occam's Razor to assert that there isn't a cosmic Alioth out there eating everything that passes beyond the red-shift horizon, but there's no way to know there isn't.

Strictly speaking there is no way to know anything, because you may happen to just be a momentary Boltzmann brain.

Re: The Zen anti-interpretation of quantum mechanics (2021)

#115

Post by nwallin »

dilap wrote: post #6

This feels like a cop out. Like sure, you can just do the math and get results and not worry about it. But what's the motivation here? When you get down to it, he seems to believe many-worlds is true, BUT holds the philosophical position that you shouldn't, like, care. Because there's no practical benefit to caring; because it doesn't help you with the calculations. But, hey, I still care! What the real nature of rea…

> It's fun & satisfying to think about,

It's neither fun nor satisfying (edit:for me) to think about. It's theoretically impossible to design and run an experiment which would either falsify Copenhagen and not-falsify Many-Worlds, or falsify Many-Worlds and not-falsify Copenhagen. Unless we can do that (we can't) then arguing about Copenhagen vs Many-Worlds is just navel gazing.

I'm fine with arguing about interpretations which are experimentally distinguishable from Copenhagen.

Re: The Zen anti-interpretation of quantum mechanics (2021)

#116

Post by superposeur »

consilient wrote: post #85
_0w8t wrote: post #79

Earlier quoted context omitted.

One problem is the preferred basis. Why decoherence selects a particular basis? Another is that decoherence still does not explain the origin of probabilities. I.e. there are models that shows how a pure classical system may arise. But we still have no explanation how a classical device interacting with a quantum system gets the value it measures.

The preferred basis is (roughly) the eigenbasis for the interaction term between the thermal environment responsible for decoherence and the decohering system in question, since those are the states that are robust to thermal noise. Outside the perturbative regime, there isn't a preferred basis because there aren't any classical observers.

To add to this, the states robust to entanglement with environment were dubbed “pointer states” by Zurek since they are the quantum states most closely analogous to the “pointer” of a measuring apparatus showing one particular result.

Re: The Zen anti-interpretation of quantum mechanics (2021)

#118

Post by lmm »

_0w8t wrote: post #98
DiogenesKynikos wrote: post #69

Earlier quoted context omitted.

The mathematical framework for modeling decoherence involves coupling an isolated system to a thermal bath, described by a density matrix. Decoherence is a phenomenon that's been studied mathematically and experimentally, not simply an interpretation or hand-waving.

This notion does not explain how the thermal bath appears. I.e. why the system interacts with a particular bath and not a superposition of such baths? At best the decoherence can try to explain how appearance of a sufficiently big classical object may trigger appearance of other objects, but it does not explain how the initial object appears.

> This notion does not explain how the thermal bath appears.

The point of the bath is it's a generic model of a large system with lots of states and interactions.

> I.e. why the system interacts with a particular bath and not a superposition of such baths?

The bath can be in a superposition state at the start, that's fine. (Indeed the whole model would be pretty useless otherwise).

Re: The Zen anti-interpretation of quantum mechanics (2021)

#119

Post by dools »

consilient wrote: post #104
dools wrote: post #102

Earlier quoted context omitted.

Really? How does light travel in a vacuum then?

In the absence of charges, Maxwell's equations reduce to `\nabla^2 F = d^2/dt^2 F`, (where F is the electromagnetic field tensor) which has solutions given by superpositions of traveling waves. What I suspect you want, however, is some sort of substance or essential nature that makes the thing go. If that's the case, then the answer is that there are no such things. Not for light, not for ordinary classical mechanics…

Right that’s the point of my original post. I see lots of people trying to understand how QM “works” when it’s just a thing that’s works the way it does. I have never seen anyone trying to understand how light moves in a vacuum, which (at least to me) seems just as mysterious if you were to try and understand it in some sort of intuitive macro physical sense.

Re: The Zen anti-interpretation of quantum mechanics (2021)

#120

Post by sudosysgen »

scottmsul wrote: post #43

Something that's always bothered me about many-worlds is that it states the number of worlds should always be increasing exponentially. Which means from an anthropic point of view, the most likely time to be born is the last ever human, with insanely exponential odds. But many people have been born in my lifetime, ergo many-worlds seems unlikely.

Well, not quite. You'd actually have an infinity of worlds with the cardinality of real numbers. So it would never increase or decrease, in the same way as there are as many numbers between 0 and 1 as numbers between 0 and 2.
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