Physicists found a new quantum paradox that casts doubt on a pillar of reality
sciencealert.com
sciencealert.com
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 becomes involved, the entanglement would “collapse” to make the friend’s observation definite.
But what if Wigner was wrong?
Well, obviously Wigner is wrong, sorry for being flippant.
In this paper (preprint here: https://arxiv.org/pdf/1907.05607.pdf), the magical thinking about consciousness seems to be transmuted into "“Absoluteness of Observed Events” (i.e. that every observed event exists absolutely, not relatively)". The authors (it appears to me) mean by this that if an observer performs an experiment, while this observer is himself in a superposition, we have to regard the outcome of the experiment as absolute (i.e. not in a superposition) because it was made by a (conscious) observer.
In my opinion, both "Absoluteness of Observed Events", and the equivalent from the layman's article, "When someone observes an event happening, it really happened", is a disingenuous and confusing way of talking about observers who are in a superposition. We have crossed over from "quantum mechanics is weird" to "these superficially intuitive but clearly false assumptions about quantum mechanics are weird".
(by the way, I read the article here: https://theconversation.com/a-new-quantum-paradox-throws-the... because that site doesn't think I'm a robot and then redirects me to the homepage after filling out the captcha)
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...
It follows from schrodinger equation, it provides no exception for macroscopic objects. You can say quantum effects indeed happen at the lowest level, and macroscopic behavior follows what happens at the lowest level. It's a question of reducibility.
> The largest objects which have been shown to act wave-like are a few thousand atoms large.
Large objects have wave-like behavior, e.g. you can't determine their size with femtometer resolution, they don't suffer from ultraviolet catastrophe and have macroscopic quantum effects like superconductivity.
Nervous system evolved from ability to respond to external stimuli to centralized control of various processes to evaluation of risks/benefits of actions and finally to predictive modeling of external processes. Rudimentary concept of “self” and understanding of surrounding environment exists in various animals, so why is it strange that an animal with most complex brain has the most sophisticated concept of “self” and it’s placement in the ultimate surrounding environment - the universe?
But this understand of the surroundings and capability to react to stimuli comes with a subjective experience, which is what is actually meant with "consciousness". This is the hard problem of consciousness[0].
0: https://en.wikipedia.org/wiki/Hard_problem_of_consciousness
I don’t think I understand the problem enough to understand why it’s a problem.
There's no need for such subject to exist.
For example, most people assume that, so far, computers do not have any inner experience.
A computer could, conceivably, execute the same functions as our brain, yet have no inner experience of anything. Numbers get in, numbers get out, without any inner experience being needed.
So why is it wrong to explain this by the necessary recursiveness of predictive modeling that includes modeling “self”? We observe the temperature but we also observe ourselves observing the temperature. First is the signal, second is the introspection of the model evoked by that signal - the feeling.
It is understandable that having an model of an observer can be useful to a brain.
But how/why does that opens a window to an actual observer, and not just a model, is the question.
And we only know that - an actual observer exists - through first hand experience. It is our most immediate and certain knowledge (Cogito, ergo sum), everything else can be questioned. Yet, there's nothing in physics or computer science that gives a hint to this being the case.
Are you sure that observer has your personality, mind and memories? Are you sure that observer is involved in any way with the world, other than observing it?
Or are those other things just part of the machinery, and quite illusory. For example our perception of time, coherent thought and personality aren't all that consistent, as we know from various experiments and observations.
Here is the crux of my point:
If there's an actual observer, let's call it "primal consciousness", but they are observing the world through the lens of a mind, which is a complex, self-referential, reactive process running on a brain and body, we don't need to say that any particular physical process "creates" consciousness. We can settle with physical processes create something complex and interesting, which runs models of itself and the world, which "primal consciousness" observes. The "mind machine" running on the physics does not contain the observer, it's observed by the observer.
That doesn't "solve" the hard problem, but it's a model with different properties and consequences than some of the other models.
It's not "wrong", it's just not parsimonious. A system can model itself without being conscious, any time you have state in a program you are doing this.
Saying that an active model of self "is" what we experience as the consciousness we experience doesn't tell us why we have that experience.
We can just as easily imagine a complex machine with an active self-model that isn't conscious, as one that is.[1] So an active self-model doesn't tell us about consciousness. This shows them to be different concepts, not different names for the same concept. Which means neither "is" the other, and "is" is not an explanation.
[1] (To be a little more picky, we can't imagine that if we insist they are the same thing, but that leads to circular reasoning here. Our questioner can imagine both, and for an explanation to explain it needs to address the question, not wave it away by offering something circular.)
It all sort of falls apart when we only talk about whether an object other than ourselves is conscious or not.
As far as we know[2], we can't distinguish consciousness of other objects by observation. A hypothetical non-conscious machine might tell us it is conscious; we will never know if it's GPT-3000 talking or if it's another being like ourselves. So eventually we'll probably decide that it's moot, and treat it as conscious if it behaves convincingly and consistently like it is.
[2] That could change, it's not ruled out.
But that doesn't deal with the "hard problem" of consciousness, which is ourselves.
For ourselves, we are in no doubt about the direct experience of our own consciousness. We might convince ourselves that it's just an active self-model, processing, because of how we think of data processing machines these days. But we shouldn't, for one because that's a weak explanation that doesn't explain, and for two because there are other active self-models in the universe, and also in the much larger abstract realm of "unexecuted" self-models that could exist (pick an RNG seed and set of rules of your choice). We don't experience those, so the one(s) we do experience are notably distinct, for no obvious reason.
it seems to me the only rebuttal is "sure, self-models can exist but it's concievable that they can exist without an observer, so why is there an observer?" and to me it sounds similar to "sure, an eye can exist without abiogenesis, so why do we only find it in organisms that resulted from abiogenesis?"
an eye is just a collection of amino-acids, nothing prevents an eye from spontaneously assembling in a primordial soup and we recognize that's absolutely impossible. however i would posit that due to configuration of physical interactions in our universe, it's virtually guaranteed for an eye to develop in any life-form that is exposed to star's radiation in earth-like conditions.
similarly, just that we can think of p-zombie doesn't mean it's a simpler system to natually occure. we don't have understanding of building blocks of consciousness like we do with chemistry and biology but the answer to the why question seems to be quite simple: we observe ourselves because we evolved to. and we can find more and more primitive examples of self-observation in more and more primitive animals, so it's not some binary phenomena.
The hard problem of consciousness is not just about the why, it's also about the how. That's exactly the magical part: how subjective, non-physical experiences (supposedly) come from physical interactions. Brushing it off as "evolution" is not sufficient to explain the how.
Coming from engineering background, I would say we need to be looking for self perpatuating loops of neuronal activity (“strange loops” may be quite appropriate concept), but how would we go about looking for them - I have no idea because I’m not up to date on modern brain scanning tech.
> Consciousness isn't magic, because chinese room in conscious
That doesn't explain anything.
Does that explain to the person experiencing consciousness why they are? No it doesn't.
It just says "something else is conscious so you are too". Which is not an explanation, it's circular.
Is it relevant if the Chinese room is conscious as well? Not really.
I am curious, though. Do you consider a system (such as a Chinese room) to be conscious if it's only implicit, by writing down the rules it should run, without actually performing any of the rules? What if it's so implicit that we don't even write down anything, we just refer to it by name, and assume we would create the rules if we needed to as the first steps in execution? Is it conscious when nothing happens at all, but it could happen? If yes, does that mean every possible thing that could occur is conscious even if it doesn't occur? Every physical possibility is conscious? The whole world of abstract mathematics is conscious? If the answer to any of those is no, where do you draw the line between conscious things (Chinese room) and not-conscious things?
>without actually performing any of the rules?
Chinese room works like human mind, so it should run to be conscious.
I'm with you but is this experimental result not new though? It seems like they're on our side and confirming what should be a non-surprising result, which is good work.
Well, panpsychism is a thing and is actually having a bit of a renaissance.
It’s not so simple. Suppose you’re in a box and observe a quantum experiment, and then I open the box and observe you. Then before I open the box you’re in a superposed state |x> + |y>, corresponding to the two possible outcomes x and y. Fine, no problem so far. But what is your own subjective experience? You, subjectively, inside the box, will only ever observe yourself to be in |x> or |y>, never |x> + |y>. Even if from the outside your brain can be said to be in a superposed state, your experience of the world is not superposed.
If you somehow had an experience of "both outcomes simultaneously", that would violate the quantum mechanical prediction that there is no mutual information between the two superpositions. There are two brain states, an x state and a y state, and they know nothing about each other.
To each brain state (with the limited information available to it) it would appear that something "definite" had happened, even though in the global picture, a superposition still exists.
When people compare QM theories they often do so on basis of the original experiments that were used to develop them. But as a discipline physics has moved well past those. Superposition has been proven and tested to exist, and we have long since moved past that phase and started building things, like quantum computers, on top of it. At this point, pretty much the only way superposition doesn't exist is that every time a physicist does something that superposition needs to work, a devil figures out what kind of result is needed to fake it and does that.
Trying to challenge superposition would kind of get same kind of results from physicists as trying to challenge the existence of electrons would get from people who build circuits. Like, if you have some interesting new theory, I am intrigued, but do understand that to get people to follow it you will need to explain how it replicates the results of what superposition would do in so many different cases that you won't be able to enumerate them in a week.
For your experience of the world to be superposed it would mean that you carry out a quantum experiment with two mutually exclusive outcomes |x> and |y> and you actually experience the superposed result |x>+|y>. This would be like opening the box in the Schroedinger's cat experiment and actually observing the cat to be |alive>+|dead>, instead of either alive or dead. Maybe it's possible, but such an experience has never been reported.
So it's "possible" but would never happen in a trillion lifetimes of the universe. You can tell the difference between that and "impossible" by watching the quantum mechanics work for a few isolated particles, and observing what it means for them to fall out of superposition equilibrium. But in practical terms, it's equivalent to impossible.
For example, the Copenhagen interpretation of QM abandons both locality and realism - particles don't have definite states, and they also communicate at infinite speed (but in a way that can't carry information).
Your friend is in the monad, now you are too. No big deal.
How did they manage to get the paper accepted in the (supposedly selective) Nature Physics journal though? Is there something we are missing?
A possible lack of absoluteness of observed events has implications for what observations may or may not be reconcilable using existing scientific methods.
> "From the point of view of the friend, the measurement result was determined long before Wigner had asked about it, and the state of the physical system has already collapsed. When now exactly did the collapse occur? Was it when the friend had finished their measurement, or when the information of its result entered Wigner's consciousness?"
This to me, shows just how hand-wavy the whole superposition/quantum collapse stuff really is. I have to say I side with Einstein with his view that everything is already in one state or the other. We don't cause the system to choose a state when we measure it. We simply discover the state it was already in. It is one thing to assign a probability to which state we will find it in. It is quite another to create an entire theory around quantum measurement.
There is nothing mysterious about this paradox. The friend performs the measurement ans discovers the state of the particle/system. Wiger doesn't know about it, but that doesn't mean it's not in that state, he just isn't aware of it yet. The fact this is a paradox just seems like silly mind games.
Superposition isn't particularly hand-wavy. It's the basis of various technologies, and of precise numerical models we use to build technologies.
Quantum collapse is hand-wavy, and that's because it is not well understood. It might not exist (in which case superposition of mind-states is a thing), or it might exist (in which case mind-states may be definite). Quantum mechanics that we can calculate doesn't give an answer either way, even though it gives lots of other answers very precisely and correctly.
> Wiger doesn't know about it, [...] just seems like silly mind games.
When only applied to a single measurement it does seem like silly mind games, you're not wrong.
The motivation for those thought experiments was to try to reason back from the consequences found from more complex behaviour observed with multiple measurements, back to a simple system with only one measurement.
But when you have many measurements with entanglement, of which there are numerous physical experiements and confirmations by now, the idea that there are just multiple, correlated probabilistic states ready to be observed that we're not yet aware of is not consistent with physically measured behaviours. Those measurements aren't hand-waving, they are hard data, even though my explanation here is hand-waving and doesn't go into it.
> I side with Einstein with his view that everything is already in one state or the other
Numerous experimental results now contradict this view, or require other strange things to be true about the world (for example superdeterminism was mentioned in the article).
Actually, it is Bell's Theorem / Inequality and related experiments that are relevant here. https://en.wikipedia.org/wiki/Bell%27s_theorem
These experiments were really the nail in the coffin for Einstein's position for most physicists. Having to admit non-local hidden variables is a pretty distasteful result.
An observer changing the outcome is a very real repeatable experiment with non wavey results.
https://physicsworld.com/a/do-atoms-going-through-a-double-s...
It's similar to the problem that has been highlighted here by OP, to quote the artical I posted
"Indeed, the results of both Truscott and Aspect’s experiments shows that a particle’s wave or particle nature is most likely undefined until a measurement is made. The other less likely option would be that of backward causation – that the particle somehow has information from the future – but this involves sending a message faster than light, which is forbidden by the rules of relativity. "
https://en.wikipedia.org/w/index.php?title=Wigner%27s_friend...
Why would I hardcode values for imperceptible objects, that would take an enormous about of ram and cpu time to constantly update values in the off chance it's needed.
Much more efficient to optimize for what the _player_ can see at their perspective. Oh and I should probably code in some error handling in the fluke event one of these particles is detected, I'll just calculate their position retroactively, the user will never be able to tell and we can host way more players due to the reduced memory.
It would seem to me that god is a junior dev and no one reviewed his pull requests.
When your underlying model of computation is full quantum computation, it's simpler to just run everything at once. It takes no energy if you run everything without picking out a scenario (but in a kind of "tree falling in a forest" way), and more energy if you select out specific scenarios to look what happened (I/O is expensive). Counter-intuitively, the computation part of quantum systems is free in ways that we consider classical computers expensive to run. It's reversible and doesn't consume any energy.
That may seem like it's avoiding the point, after all what does it take to run the "underlying model of computation".
But what I'm trying to say is that "quantum all the way down" (see also turtles) is as much a valid model as "mechanical computation all the way down", which your picture relies on. Neither of them is more fundamental.
It may seem like quantum-all-the-way-down is a bit artificial, because we can in principle run quantum simulations on classical computers, which seem simpler. But it turns out we can't. There is a fundamental intractability barrier for simulations above an arbitrary tiny size, which means we can only simulate interesting quantum systems using other quantum systems. It really is quantum-all-the-way-down.
If god came up with the quantum-all-the-way-down version, I'd say that's pretty clever, because it's way more efficient than anything you would implement, with your old-school classical RAM and classical CPU.
That being said if it was demonstrated that un collapsed wave functions are somehow more efficient to calculate that would definitely give credence to the simulation hypothesis.
Well said. I can certainly imagine a few functions that may prove to be more efficient at generating waves than fixed known positions + velocity for every subatomic particle in the universe.
Here's the part that really takes us off the rails, if we assume for a minute that we are in a simulation and that the parent world has godlike resources compared to our own and they likely have similar hardware concepts (ram, cpu, gpus, maybe even ASICS) then what functions are more efficient would depend on which hardware they have less of.
If ram is plentiful why not have fixed known values for every particle? Store it in memory and let the gpu detect collisions.
If gpus are plentiful (my guess) and we're bound by ram limitations, best to only store positions of things that are visible and clear the rest out of ram for more important calculations.
Imagine how inefficient it would be to render and simulate black holes colliding on the other side of the universe if the players will never even notice. Just queue up the function and run it on off-peak hours. Save the extra server resources for other simulations running in parallel.
If I'm right - a big if - we're likely an anomaly or early prototype among the simulations, one in which the dev team never imagined a race would evolve and progress enough to measure the bounds of their container. If I'm right again on this last point, we're likely being monitored closely to decide if subsequent patches require more resources to simulate completely and avoid player's realizing they're in a simulation or accept it as a remote possibility and move on.
When we build simulations for ourselves, they're always attempting to approximate reality as closely as possible. The goal is to learn useful things about our own world or society and to try out many forking paths, in a simplified representation of reality.
If we're in a simulation it stands to reason that whoever is running it is somewhat human-like, and exists in a world that has basically the same physical laws ... or at least, similar enough that sociological and technological development would be the same. For instance, the speed of light barrier is pretty damn inconvenient for us but would be great at blocking an arbitrarily large population and state space explosion. And why are these magic physical constants so arbitrary anyway?
If we are in a simulation, and our simulators did want to limit their resource consumption, adding in a few physical laws that are never really a problem in daily life and which block us from colonising the galaxy would be a nice way to do it.
As an aside, I think one of my personal arguments that we're in a simulation is that we live in such an interesting time. We're beyond a world with 95% farmers. Technology is advancing faster than ever before. It's such a critical time in human history and the 20th century is personally where I'd choose to start a human simulation. It's convenient that this is our shared spot in time.
what you’re describing is called “simulation theory” and it has been proposed and discussed at length
i think lazy evaluation makes sense in that context. i also think that having a few basic rules and after that applying them consistently across your simulation space make sense. if your basic space unit of reality is way smaller than the sims in it can perceive and measure they’re gonna start making stuff up
Good lord, some people here are definitely on the spectrum. FYI that was an attempt at humor. In case you want to mimic human social behavior in the future: you don't _disagree_ with a joke, you either find it funny or you don't.
> what you’re describing is called “simulation theory” and it has been proposed and discussed at length
I'm aware of the theory, just like everyone else whose seen the matrix or read Elon's Twitter feed. For the record, I was merely illustrating a point; both our universe and the code we write share certain optimizations that would seem to be too coincidental to be random.
Maybe he was disagreeing with your entire assesment and that your joke was neither funny or unfunny, but incorrect
> some people here are definitely on the spectrum. FYI that was an attempt at humor. In case you want to mimic human social behavior in the future ..
_Your_ failed attempt at humour doesn't justify labeling and gaslighting the person who didn't "get it", if anyone can ever consider that to be a joke.
> For the record, I was merely illustrating a point
Illustrating a point or making a joke? In either case, it doesn't justify your "human social behavior" of attacking the personality traits of the person disagreeing with you. My suggestion to you -in the future- accept that someone can have a different opinion and that you could be wrong and try to counteract that without resorting to labeling and gaslighting.
"God is a junior dev", is a mildly funny trope that has existed as long as I've been on the internet. I believe there's an xkcd about it where God says "we hacked most of it together with Perl".
Anyway, it's hard to tell what is and isn't a joke on the internet due to lack of vocal inflection. Maybe consider going easier on people when this happens in the future.
i did find the idea of god being a senior dev/architect grumpy type being funnier then your overused tired meme
If the universe is actually compressible, then object permanence may actually be a trick, like it is in video games. Objects are generated on demand and deleted to save space and processing.
If it's not compressible, which is where I lean, then the full universe must be fully computed every time. No savings can be made, and any delay in computing an object might propagate and cause recalculation cascades for other objects. I lean this way because from my layman's understanding, quantum mechanics act similarly to random seeds, which increases entropy by a lot.
If it's not compressible, then the smallest computer able to simulated the universe is at least as big as the universe itself.
> When someone observes an event happening, it really happened.
Given the experiment from the paper, I would rephrase this assumption as "it's not possible to rewind things". But obviously inside a computer simulation made up of operations that are all individually reversible, it's trivial to rewind things.
The experiment sets up a situation where certain information is reversibly recorded, and then the records are unmade by temporarily rewinding. The rewinding is obfuscated by hiding it inside of a measurement that is incompatible with the presence or absence of the record. I guess the authors might disagree about the measurement implying rewinding, but as a bit of evidence I'll note that Scott Aaronson and Yosi Atia have shown that performing the measurement in question over a simulated agent is at least as expensive as rewinding the simulated agent [1]. Whatever is being done, it is doing some seriously expensive screwing around with the agent's state. It's like the experiment has a step where you feed the human through a giant meat processing plant, and for some reason everyone is pretending that's not somehow important.
Basically, the authors are appealing to the intuition that humans are big complicated in-practice-irreversible things, so clearly a record is permanent if it has affected the state of a human. But then they imagine instantiating the human's state inside a ridiculously powerful computer capable of reversibly simulating time advancing and of performing operations that have been engineered specifically to mess with the presence or absence of the record's effects on the human's state. Surprise surprise, the record gets messed with. Then for the actual experiment the big complicated ball of dependent spaghetti that is a human is replaced by a nice simple photon going along one path or another path.
Do physicists axiomatically treat a "conscious observer" as an atomic unit? It seems the case based on neurological and psychological research that the mind is actually not a single unit but many units working together, and the sense of a singular self is an illusion, which would correlate with the fact that we are made up of a conglomeration of atoms and systems made of these atoms.
When we say that a person is observing a quantum system, could this actually be a cascade of observations of various parts of the mind rather than a singular event, since the mind is not monolithic?
On a side note (and perhaps unrelated), if different parts of the brain/mind could be in different quantum states, could this be a factor in how the mind operates?
The concept of "measurement" is just executing code on one node that populates local registers- "creating" not "measuring". Yes- by running code you are pulling on a reality fabric that we still know almost nothing about. But I find it easier to visualize than relying on my colloquial/non-QM intuition in words like "measuring"- which implies something like a single centralized reality database, not a creative decentralized infrastructure. QM experiments seem to create things, not measure them.
Would love to learn metaphors of folks in the space.
If you’re interested in QM, read “The Theoretical Minimum”; the second book gets into QM. There are video lectures of the same material that complement the series, we’ll.
Whether one is more appropriate than another I don't know. But I find the decentralized model produces more interesting naive questions for me to puzzle over. Of course those questions likely lead in a completely wrong direction. Cheers, thanks for engagement.
> 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 it really happened in the reality of the observer (and maybe not in other realities)? What is meant by "reality"? Some insight is to be gained by precising what we call the reality, in relation to the corpus of all the observations in what we believe is our universe.
Consider for example the system composed of a pool table. In classical physics we can assume we can always measure the position and momentum of all balls in the table. But what would happen if measurement was not possible without big changes in position and velocity? Suddenly the whole notion of "observation" would lose its meaning, and the only way to describe the pool table is as a probabilistic mesh of balls moving around in uncertain directions.
That would give credit to the multiverse interpretation of quantum mechanics then.
Maybe the observation process of a quantum phenomenon by a human observer is akin to the orthogonalization of a matrix:
as the observer becomes entangled with the observed particle, each possible observer-eigenstate (i.e. any observer in "his reality") ends up observing an eigenstate of the observed quantum phenomenon, instead of a dirty superposition.
To call it "orthogonalization of the observer-observed system" would be more descriptive than "wave-collapse", but the main difference is that the orthogonalization treats in parallel all possible outcomes, each linked to a different state (outcome) of the observer too, whereas the "collapse" view insists on the fact that the observed eigenstate is unique. And moreover, at least in mathematics, there are conditions for the orthogonalization to be possible at all, so that should be interesting.
This is the origin of the problem of observation - the predictions of quantum mechanics break down at some point, and we have no idea why. In particular, this happens very clearly when our measurement instruments directly interact with a quantum system, so we call this 'the measurement problem'.
Of course, we can postulate that in fact, despite all of our observations, both subjective and objective, the classical world also behaves quantically but we just can't notice it happening (e.g. the Many Worlds interpretation does this).
We can also say that the quantum world does NOT in fact behave that way, but that the universe is perfectly deterministic and just set up in such a way that we can never observe events that contradict this vision of the universe (superdeterminism claims this - that for example you will always happen to choose the right dial on a measurement apparatus to observe entanglement, but that there is no fundamental reason why that should happen - it could theoretically happen otherwise, but in this universe, ever since the big bang, it has been decided that at some point you will set that dial in the particular way that will make you observe the entanglement result).
There are other theories that postulate that quantum mechanics is in fact deterministic, but very hard to predict, but there are non-local effects (deBroglie-Bohm pilot wave theory is such an example).
We can also ignore the whole hope of trying to understand all this, and simply use the math if and when we need it to predict particle phenomena.
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.
Probabilities are useful when you don't have perfect knowledge. But yes, they are an illusion. In truth, every event has a 100% chance of happening. And things that didn't happen aren't real events, they just seemed to be possible, but we were wrong.
In general, all of modern science, starting with quantum mechanics, depends on the idea that statistical independence exists. To truly abandon this idea, we would abandon almost all of the mathematical apparatus that has given us QM and all experimental observations of QM.
At least as I was using the term, no one has perfect knowledge.
> ability to randomly choose participants
Here, pseudorandom is good enough, and I think all we have.
The bell inequalities have been shown to hold true when the measuring 'decision' was left to signals coming from a pulsar some untold number of millions of light years away, implying that the particle you just generated today has its hidden state correlated with the state of that pulsar that many million years ago. So it seems that nature must be much more highly correlated that we would expect, so I don't know what you would trust as pseudo-random anymore.
Perhaps at some point we will be able to do the same triggered by fluctuations in the cosmic background radiation, proving that either quantum entanglement is not both local and real, or that the state of the two particles you just generated was decided at the big bang in such a way as to seem like the Bell inequalities are true.
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 system and choose to consider only a subset of its degrees of freedom. When you do that, what results is a "mixed state" which behaves classically. This is not a reflection of any (meta)physical reality, it's just a consequence of your point of view. But here's the thing: you yourself are a subset of a quantum system, and so you yourself have no choice but to take this point of view. You cannot ever take the "god's-eye view" and "see" the whole system. That is fundamentally impossible because "seeing" requires copying information, quantum states can't be copied yada yada yada. Even God cannot "see" the god's eye view!
You seem to be saying that a computer can only be called a quantum computer if it never decoheres. Or perhaps that it is only usable in some sort of batch-mode, like mainframes with punch-card decks, with each calculation cycle being a laborious one-shot affair.
I have little doubt that many near-future quantum computers will be used in exactly that mode, but also that at some point thereafter their coherence/decoherence cycles will start to be measured in Hz, Khz, etc.
Therefore there should in principle be no barrier to a quantum computer participating in a Turing test, or any other use-case that requires interaction.
Not quite. I'm saying that in the context of using a quantum-computer to play the role of Wigner's friend, it must be isolated from the ultimate observer. If you're not going to require that, you might as well just do the experiment with an actual human.
An AI could use Grover search when trying to find a good enough response. That would be like part of the AI going into and out of superposition for an efficiency boost.
Many quantum tasks are more efficient if certain catalyst states are present [1][2]. That would be like a part of the AI staying permanently in superposition while still ultimately contributing to classical results, again for an efficiency boost.
Ok, so make classical pointers to quantum states and copy the pointers instead of the quantum states :)
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.
I guess one would have to demonstrate that the program implements an AI by running it on a computer with I/O, then move the same program over to an isolated quantum computer once it's passed that test. Maybe not completely philosophically satisfying, but should work in practice.
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...
Each quantum calculation can be collapsed to a state, and that state could then be fed to the next quantum calculation etc. etc.
Would you call a series of such quantum calculations a quantum computer, or not?
In a recent story I asked in general and others told me that there were thought experiments that became proper experiments. But it seems that they were somewhat different, more like pre-experiments. When something gets stuck in the thought experiment category, it's more like a no-experiment.
I have no problem admitting that this kind of ellucubration is useful to anticipate problems. But extracting conclusions from an impossible setup? That's like asking what would happen if an irresistible force meets an immovable object.
Wouldn't quantum entanglement enable a comparable ability?
Okay, so we have to kill one. The easiest one to kill is
> It is possible to make free choices.
In other words, quantum mechanics is incompatible with free will. This is clearly shocking to any physicist who believes in Free Will (as defined by philosophers thousands of years ago). But hasn't Free Will been recognized as nonsense for at least two centuries by now?
Among some, sure and it's not just physicists [1].
Acknowledging that the concept we've called free will is not likely to be real has some troubling implications regarding how we've structured our society which is likely one of the reasons it's not talked about very often.
Isn't unpredictability enough?
Me neither.
(To make it clear: the content is interesting, even if clearly for popular science audience (some statements about physics are false, e.g. "These are all intuitive ideas, and widely believed even by physicists." The title is worth a tabloid.)
we also pretend that consciousness is something special and altering the state a somewhat complicated wetware had consequences on “reality”. it doesn’t.
the measurement problem is an extremely good example of how we think. a measurement does not make sense to a cow. it’s abstract. we made it up. we have conventions that help make it useful, but those conventions break down when our senses (or things we use to amplify out senses) cannot measure what we want to measure.
Note: IANAP