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Physicists found a new quantum paradox that casts doubt on a pillar of reality

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Re: Physicists found a new quantum paradox that casts doubt on a pillar of reality

#51

Post by c1ccccc1 »

lisper wrote: post #30

> if the "friend" is a human-level artificial intelligence running in a massive quantum computer. Well, there's your problem right there. No AI can run on a quantum computer. Intelligence is inherently a classical phenomenon because it requires copying information, and quantum states cannot be copied, only classical states can be copied. The classical world "emerges" from the quantum world when you take a quantum sys…

A good point, but quantum computation can do anything that reversible classical computation can. If you do your entire computation while keeping all the qubits in the {|0>, |1>} basis, then performing a CNOT onto a qubit initialized to |0> will work as a classical copy. (It will fail to truly copy the quantum state, but that's fine.) You just need a large enough supply of qubits initialized to |0> for all the copies you plan to do.

Re: Physicists found a new quantum paradox that casts doubt on a pillar of reality

#52

Post by nicoffeine »

lisper wrote: post #30

> if the "friend" is a human-level artificial intelligence running in a massive quantum computer. Well, there's your problem right there. No AI can run on a quantum computer. Intelligence is inherently a classical phenomenon because it requires copying information, and quantum states cannot be copied, only classical states can be copied. The classical world "emerges" from the quantum world when you take a quantum sys…

> Intelligence is inherently a classical phenomenon because it requires copying information, and quantum states cannot be copied, only classical states can be copied

I don't agree with this. The recent research in quantum biology[1] suggests that biology at least can read from quantum states -- birds may use it to navigate, our sense of smell may be a quantum interaction, and plants appear to use quantum properties to achieve almost perfect efficiency for photosynthesis. The human eye may be able to detect a single photon.[2] General quantum activity also seems possible, since lithium-6 and lithium-7 appear to produce different pharmacological results despite being only one neutron apart[3].

I also fall into the camp of supporting the Orch-OR theory of consciousness[4], which claims that our interpretation of a classical system for brains is incorrect, and that neurons have internal structures called microtubules which can maintain quantum states. Microtubules have been known to exist for decades, but it was thought that their purpose was purely structural. Anirban Bandyopadhyay demonstrated[5] that these structures appear capable of storing information at the quantum level.

Orch-OR would explain how anesthesia works, and how biology with classically simple brains are capable of extremely complex lifecycles and self-organization. I don't know enough about neuroscience to have any real insight on its validity, but there seems to be a huge disconnect between where we think we are with AI and the results so far. I have watched a butterfly navigate through a chain link fence on a windy day, and that kind of computation doesn't seem possible in a classical model, from a space or an energy perspective.

> Even God cannot "see" the god's eye view!

The strongest argument I see for a concept of God is the fact that the universe doesn't break. Quantum brains provide some interesting possibilities for the privacy of thought co-existing with some sort of perfect originator. In any case, given the amount of computation it would take just to model the biology of one person and the underlying quantum states, I am almost positive that we are not in a simulation.

[1] https://royalsocietypublishing.org/doi/10.1098/rspa.2018.067...

[2] https://www.nature.com/news/people-can-sense-single-photons-...

[3] https://www.quantamagazine.org/a-new-spin-on-the-quantum-bra...

[4] https://en.wikipedia.org/wiki/Orchestrated_objective_reducti...

[5] https://aip.scitation.org/doi/abs/10.1063/1.4793995

Re: Physicists found a new quantum paradox that casts doubt on a pillar of reality

#54

Post by brundolf »

bondarchuk wrote: post #6

The original Wigner's friend paradox: https://en.wikipedia.org/wiki/Wigner%27s_friend The paradox seems to rest on magical thinking about consciousness, and if one simply accepts that a conscious observer can be in a superposition like any other piece of matter, the paradox is resolved. And, from the article: For Wigner, this was an absurd conclusion. Instead, he believed that once the consciousness of an observer be…

It's interesting the way some scientists have been biased into this kind of magical thinking, probably because the integrity of conscious observation is so central to their practice/worldview. Nobody is free from the pressure of cognitive dissonance.

Re: Physicists found a new quantum paradox that casts doubt on a pillar of reality

#55

Post by lisper »

adrianN wrote: post #37
lisper wrote: post #30

> if the "friend" is a human-level artificial intelligence running in a massive quantum computer. Well, there's your problem right there. No AI can run on a quantum computer. Intelligence is inherently a classical phenomenon because it requires copying information, and quantum states cannot be copied, only classical states can be copied. The classical world "emerges" from the quantum world when you take a quantum sys…

I'm not convinced that intelligence requires copying information in the way that the no-cloning theorem forbids. Approximate cloning is not forbidden for example.

The problem is not copying internal states, the problem is I/O. A given instance of a quantum computation can only be queried once before it decoheres and goes "poof" because the querying process itself decoheres the system. So a quantum computer can never pass the Turing test because it cannot even participate in the Turing test without destroying itself.

Re: Physicists found a new quantum paradox that casts doubt on a pillar of reality

#57

Post by kmm »

bondarchuk wrote: post #6

The original Wigner's friend paradox: https://en.wikipedia.org/wiki/Wigner%27s_friend The paradox seems to rest on magical thinking about consciousness, and if one simply accepts that a conscious observer can be in a superposition like any other piece of matter, the paradox is resolved. And, from the article: For Wigner, this was an absurd conclusion. Instead, he believed that once the consciousness of an observer be…

We're veering away from physics here, but isn't consciousness actually quite "magical". It's beyond remarkable to me that stimulating nervous tissue, composed of quite mundane things like protons and electrons, yields a subjective experience. I know many people reject the hard problem of consciousness, but to those who don't, the implications of thought experiments like Wigner's friend, like superpositions or entanglement of subjective experiences, are truly paradoxical. You are calling certain viewpoints obviously wrong or false because you adhere to certain philosophical viewpoints. There's nothing wrong with that, and they're all justifiable, but none of them are complete consensus among philosophers.

Coming back to physics, there's an assumption you and other commenters are silently making, which is that quantum mechanics is even applicable to macroscopic objects like humans. The largest objects which have been shown to act wave-like are a few thousand atoms large. While it's indisputable that at the lowest level the universe is fundamentally quantum mechanical, it's a little brazen to extrapolate that over more than 20 orders of magnitude. As a physicist myself, I'll believe it when I see it, and I'm looking forward to getting results from proposed experiments like FELIX and its successors.

https://en.wikipedia.org/wiki/Free-orbit_experiment_with_las...

Re: Physicists found a new quantum paradox that casts doubt on a pillar of reality

#58

Post by cmehdy »

coliveira wrote: post #38
henearkr wrote: post #33

The part that seems the most dubious to me is the "choice": > 2. It is possible to make free choices, or at least, statistically random choices. I don't see what would be really compelling in that. If it's false it would just mean that our actions are all kind of mechanistically decided by other events, and that does not shock me. Other point: > 1. When someone observes an event happening, it really happened. What if…

The main problem of quantum interpretation is the supposed, artificial, distinction between observer and observed system. In a quantum world this distinction is not possible, every event capable of "observing" a system is itself part of the system, modifying it. That's why such interpretations (postulating this separation) give all kinds of strange paradoxes that are impossible to solve. In the quantum world, there i…

Even in the classical world we measure that pool table by interacting with it. If I stand next to the table and see it, it's because light hit it and then hit my eyes - but I've absorbed whatever light might have gone on its course through me as an observer and maybe hit the table again eventually (attenuated), and I also happen to emit some light myself. My body being present and warm, my breathing of air in the room, etc.. creates convection currents of air, which affect the fluid mechanics of the same volume of air that the balls are in.

My brain can't really perceive much of any of that and does a lot of filtering of information, and we've designed the pool table to be something we grasp and play with easily so the relative inertia of the balls will mostly overcome all the more minor terms to take into account wrt fluid mechanics, but all of that is classical physics already. "Closed systems" might only exist conceptually.

Re: Physicists found a new quantum paradox that casts doubt on a pillar of reality

#59

Post by c1ccccc1 »

amelius wrote: post #8
menzoic wrote: post #4

Veritasium has a great video that explains the concept of parallel worlds vs wave collapse in a single world https://youtu.be/kTXTPe3wahc

Nice video. Now I wonder if God uses structurally shared data structures in his implementation of the world. I also wonder if there can be a kind of continuous description of branching that is more amenable to calculus than the discrete tree-like branching.

I think MWI actually predicts continuous branching. The prescription for MWI is just to run the Schrodinger equation forwards in time. So the branching would look like one blob of probability gradually becoming bimodal, and then splitting into two components with less and less overlap. (There might also be 3-or-more-way branches, not just binary splits.)

Re: Physicists found a new quantum paradox that casts doubt on a pillar of reality

#60

Post by lisper »

c1ccccc1 wrote: post #51
lisper wrote: post #30

> if the "friend" is a human-level artificial intelligence running in a massive quantum computer. Well, there's your problem right there. No AI can run on a quantum computer. Intelligence is inherently a classical phenomenon because it requires copying information, and quantum states cannot be copied, only classical states can be copied. The classical world "emerges" from the quantum world when you take a quantum sys…

A good point, but quantum computation can do anything that reversible classical computation can. If you do your entire computation while keeping all the qubits in the {|0>, |1>} basis, then performing a CNOT onto a qubit initialized to |0> will work as a classical copy. (It will fail to truly copy the quantum state, but that's fine.) You just need a large enough supply of qubits initialized to |0> for all the copies…

> quantum computation can do anything that reversible classical computation can

Well, yeah, but that "reversible" hedge is quite significant. Reversible means you have to retain all of your intermediate states, and it is far from clear that you could build a reversible AI that would run for more than a few milliseconds before consuming all of the available resources in its light cone.

> You just need a large enough supply of qubits initialized to |0> for all the copies you plan to do.

Yes, and that produces exactly the same problem: it is far from clear that there are enough qbits in the universe to build a quantum AI this way.

You also have a more fundamental problem, which is that neither quantum computers nor reversible classical computers can do I/O, so how are you going to demonstrate that this thing is in fact an AI? It can't even participate in a Turing test, let alone pass one.

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