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Do electrons think? (1949)

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Re: Do electrons think? (1949)

#41

Post by tntn »

crazygringo wrote: post #2

Note that, contrary to popular understanding, it isn't even established that quantum mechanics is indeterminate or not subject to strict cause-and-effect. It's indeterminate according to the mainstream Copenhagen interpretation, but de Broglie–Bohm theory [1] ("pilot wave theory") is an interpretation that is entirely deterministic, and its assumptions result in exactly the same final equations as the Copenhagen one.…

I'm a big fan of epistemological interpretations of QM. Everything becomes far less mysterious when it is a theory of knowledge, IMO. Wavefunction collapse? No wonder it collapsed: it represents your knowledge and you just observed the system.

Re: Do electrons think? (1949)

#42

Post by CuriouslyC »

tbabb wrote: post #37
crazygringo wrote: post #2

Note that, contrary to popular understanding, it isn't even established that quantum mechanics is indeterminate or not subject to strict cause-and-effect. It's indeterminate according to the mainstream Copenhagen interpretation, but de Broglie–Bohm theory [1] ("pilot wave theory") is an interpretation that is entirely deterministic, and its assumptions result in exactly the same final equations as the Copenhagen one.…

De Broglie-Bohm is probably not the correct theory, since (if I am not mistaken) it's not reconcilable with relativity, and has a host of other problems which led its original proponents to abandon it. Copenhagen is also probably not correct, though it is still frustratingly mainstream. Copenhagen has the well known problem of lacking a physical definition of "observer", but it also has conflicts with delayed choice…

The stock many worlds hypothesis has a couple of really big problems. For one, the information content of the multiverse expands exponentially towards infinity. Second, it basically makes the amplitude of the wavefunction meaningless, since everything that can happen, does. If you make the assumption that the measure of the multiverse is fixed and quantized, things become a bit less conceptually problematic, but that breaks the math. Regardless, it still has the fewest problems among current paradigms.

Re: Do electrons think? (1949)

#43

Post by foxes »

lmm wrote: post #21
crazygringo wrote: post #2

Note that, contrary to popular understanding, it isn't even established that quantum mechanics is indeterminate or not subject to strict cause-and-effect. It's indeterminate according to the mainstream Copenhagen interpretation, but de Broglie–Bohm theory [1] ("pilot wave theory") is an interpretation that is entirely deterministic, and its assumptions result in exactly the same final equations as the Copenhagen one.…

It's just many-worlds style wave-function realism with some extra epicycles on top. Treating the wavefunction as physically real is perfectly reasonable. Treating the wavefunction as physically real and then assuming there are also pseudoclassical particles on top adds nothing except appealing to the confused - "oh no, the particles aren't in a superposition, the particles are just ordinary classical particles... all…

I don't think the wavefunction is a physical object. It's just a mathematical abstraction to describe reality, theres no real justification to treat it as something physical?

Re: Do electrons think? (1949)

#44

Post by tbabb »

effie wrote: post #40
tbabb wrote: post #37

Earlier quoted context omitted.

De Broglie-Bohm is probably not the correct theory, since (if I am not mistaken) it's not reconcilable with relativity, and has a host of other problems which led its original proponents to abandon it. Copenhagen is also probably not correct, though it is still frustratingly mainstream. Copenhagen has the well known problem of lacking a physical definition of "observer", but it also has conflicts with delayed choice…

In the Everettian interpretation, experiments do not have results (!) and it is not clear what probability even means, much less how the Born rule and observed statistics arise. That's because it is not a theory about our world, but about an imagined world where the only things existing is the psi function. > every possible outcome of a quantum measurement actually happens in due proportion to the probabilities descr…

I am not sure what you mean by "experiments do not have results." A measurement in Everett is the environment becoming entangled with the measured system, and a "result" is a particular basis of the combined wavefunction.

Re: Do electrons think? (1949)

#45

Post by tbabb »

CuriouslyC wrote: post #42
tbabb wrote: post #37

Earlier quoted context omitted.

De Broglie-Bohm is probably not the correct theory, since (if I am not mistaken) it's not reconcilable with relativity, and has a host of other problems which led its original proponents to abandon it. Copenhagen is also probably not correct, though it is still frustratingly mainstream. Copenhagen has the well known problem of lacking a physical definition of "observer", but it also has conflicts with delayed choice…

The stock many worlds hypothesis has a couple of really big problems. For one, the information content of the multiverse expands exponentially towards infinity. Second, it basically makes the amplitude of the wavefunction meaningless, since everything that can happen, does. If you make the assumption that the measure of the multiverse is fixed and quantized, things become a bit less conceptually problematic, but that…

> For one, the information content of the multiverse expands exponentially towards infinity.

I don't agree. I would say that the biggest difference-- really, the fundamental difference-- between Everett and Copenhagen is that Everett says that the state evolution of the wave function is always unitary, while Copenhagen says that it's only unitary sometimes but not others (and don't ask about how to calculate which way it will act).

Under unitary state evolution the volume of phase space is preserved and no information is globally created or destroyed. So the "branching" picture of Everett is not precisely correct, though it is handy language for building intuition.

This should not be surprising because of complementary observables-- confining the state of one property will cause some other property to become proportionally unconfined, per Heisenberg.

Re: Do electrons think? (1949)

#46

Post by retsibsi »

tntn wrote: post #41
crazygringo wrote: post #2

Note that, contrary to popular understanding, it isn't even established that quantum mechanics is indeterminate or not subject to strict cause-and-effect. It's indeterminate according to the mainstream Copenhagen interpretation, but de Broglie–Bohm theory [1] ("pilot wave theory") is an interpretation that is entirely deterministic, and its assumptions result in exactly the same final equations as the Copenhagen one.…

I'm a big fan of epistemological interpretations of QM. Everything becomes far less mysterious when it is a theory of knowledge, IMO. Wavefunction collapse? No wonder it collapsed: it represents your knowledge and you just observed the system.

That (to my complete layman's eye) seems reasonable, but is it really much more than shuffling labels around? It seems the 'deeper' mystery remains: what is going on at the fundamental level of reality? (Or, in other words, why do our observations have these properties?) Whether or not that question is answerable -- or even meaningful -- I think we'll always be driven to ask it.

Re: Do electrons think? (1949)

#47

Post by im3w1l »

tbabb wrote: post #44
effie wrote: post #40

Earlier quoted context omitted.

In the Everettian interpretation, experiments do not have results (!) and it is not clear what probability even means, much less how the Born rule and observed statistics arise. That's because it is not a theory about our world, but about an imagined world where the only things existing is the psi function. > every possible outcome of a quantum measurement actually happens in due proportion to the probabilities descr…

I am not sure what you mean by "experiments do not have results." A measurement in Everett is the environment becoming entangled with the measured system, and a "result" is a particular basis of the combined wavefunction.

If you square the probability amplitude and take the absolute value, that you get something that works very much like a probability. But there is nothing in many-worlds theory that says this quantity has any special significance.

Re: Do electrons think? (1949)

#48

Post by tbabb »

im3w1l wrote: post #47
tbabb wrote: post #44

Earlier quoted context omitted.

I am not sure what you mean by "experiments do not have results." A measurement in Everett is the environment becoming entangled with the measured system, and a "result" is a particular basis of the combined wavefunction.

If you square the probability amplitude and take the absolute value, that you get something that works very much like a probability. But there is nothing in many-worlds theory that says this quantity has any special significance.

I still either don't see why you say that, or don't follow what you are trying to say.

The Born rule is a fundamental feature of all quantum theories, and I don't see why Everett is an exception.

If you want an intuitive picture of what the squared amplitude means, it seems that it would suffice to think of it as the fraction of phase space which evolves into the configuration associated with that amplitude.

Re: Do electrons think? (1949)

#49

Post by beautifulfreak »

I wonder if anyone here would be so kind as to explain Schrodinger's argument. I'm not grasping it. Is he making a fundamental point about the degrees of freedom an electron can have, delimiting ideas about how a brain can process thought with the help of self-willed electrons? Or is it confined to whether an electron itself can have thought. What point is he making in the debate about whether humans are automata? I'll read it again, but it's subtle and I might not understand quantum mechanics sufficiently to understand it.

Re: Do electrons think? (1949)

#50

Post by kjeetgill »

crazygringo wrote: post #2

Note that, contrary to popular understanding, it isn't even established that quantum mechanics is indeterminate or not subject to strict cause-and-effect. It's indeterminate according to the mainstream Copenhagen interpretation, but de Broglie–Bohm theory [1] ("pilot wave theory") is an interpretation that is entirely deterministic, and its assumptions result in exactly the same final equations as the Copenhagen one.…

I'm not super knowledgeable but I love this series, Looking Glass Universe, on the subject [0,1]. Specifically, she goes into some common but wrong beliefs about Bohemian Mechanics including that there is NO quantum weirdness. There is - it's called contextually. I don't know more than that.

[0]: https://www.youtube.com/watch?v=r0plv_nIzsQ&t=2s [1]: https://www.youtube.com/watch?v=Qz4CHI_W-TA

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