Superdeterminism: The path we didn’t take
backreaction.blogspot.com
backreaction.blogspot.com
But, similarities in equations surely can be misleading ;)
The math is way over my head, but this sub-statement resonates with me deeply and has been my crude but overarching view of the physical world and our interpretations of it for a long time - except applied more broadly - as a description of the interaction between multiple layers of abstractions of reality (whether the things behind those designated abstractions are natural or human made, e.g transistors for digital logic, a "deterministic" quantized layer created atop a non-deterministic one).
It is layered because each deterministic one is only effectively deterministic by being predictable "enough" in a highly uniform way. The next layer then often becomes viewed from a probabilistic perspective again due to chaotic interactions of the previous one (often computationally irreducible). The lack of access to massive initial state and in-feasibility to compute prediction based on the underlying mechanisms are the only reason we switch back to the probabilistic view at these non-fundamental levels of abstraction.
Now I understand quantum physics is not supposed to be such a layer, because we didn't start out with an existing working concept of what's underneath it in the way we know whats underneath equations for some statistical mechanics for example - but from the perspective of a complete amateur the idea of superdeterminism seems quite natural! - yet at the same time I can't help wonder if there is yet another probabilistic layer underneath :)
Skimming the actual paper[2] I'm not really seeing a convincing explanation, this in particular just strikes me as hard to believe / failing Occam's razor:
The belief that such tests tell us something about (the implausibility of) Superdeterminism goes back, once again, to the idea that a state which is intuitively “close” to the one realized in nature (eg, the wavelength of the light from the distant quasar was a little different, all else equal) is allowed by the laws of nature and likely to happen. However, in a superdeterministic theory what seems intuitively like a small change will generically result in an extremely unlikely state; that’s the whole point. For example, in a superdeterministic theory, a physically possible counterfactual state in which the wave-length of the photon was slightly different may also require changes elsewhere on the past hypersurface, thereby resulting in the experimenter’s decision to not use the quasar’s light to begin with.
"Reality is a giant deterministic conspiracy" is more plausible than abandoning local realism? They do (kinda?) propose an experiment at least?
[1] https://www.quora.com/Why-do-some-crackpot-scientists-go-aft... [2] https://arxiv.org/pdf/1912.06462.pdf
A much more detailed way of saying about the same thing as the above sentence: https://backreaction.blogspot.com/2019/09/the-trouble-with-m...
Indeed it doesn't, but the Born rule is much smaller and simpler than the notion of collapse that other approaches rely on.
> A much more detailed way of saying about the same thing as the above sentence: https://backreaction.blogspot.com/2019/09/the-trouble-with-m....
This post doesn't seem to understand many-worlds. There is no concept of a privileged "detector". All that many-worlds postulates is that detectors, experimenters, and anything else you might measure with obeys the normal rules of physics, and can be put into an entangled superposition just like anything else.
First, not all of the other approaches have a collapse. e.g. Bohm and a few lesser known others don't have it. Second, it's not clear Born is 'smaller and simpler' than the collapse of some other interpretations. e.g. in QBism collapse arises naturally from the theory and it would be weird if collapse didn't happen.
" This post doesn't seem to understand many-worlds... anything else you might measure with obeys the normal rules of physics"
Her point is that what MWI tries to derive everything from the Schrödinger equation alone, but it still needs to solve its equivalent of the measurement problem (why can we only get certain results on the evolution of this branch?), but that can't be done since Schrödinger is linear and the equivalent problem is not.
Bohm is just MWI with a bunch of extra epicycles.
> Second, it's not clear Born is 'smaller and simpler' than the collapse of some other interpretations. e.g. in QBism collapse arises naturally from the theory and it would be weird if collapse didn't happen.
I'd be interested in hearing more, but from a quick look I'd argue that the notion of an agent who should evaluate subjective probabilities is more complex than objective probability numbers.
> Her point is that what MWI tries to derive everything from the Schrödinger equation alone, but it still needs to solve its equivalent of the measurement problem (why can we only get certain results on the evolution of this branch?)
That's not true though. The branching behaviour is inherent in the Schrödinger equation.
Heh. I've heard MWI is just an hidden variable theory with the other branches being the hidden information. Slightly more seriously, the two did develop independently.
"I'd be interested in hearing more..."
IMHO, QBism is relatively intuitive if/once you accept the subjective probability premise (which means probability one isn't same as 'true'!), but I'm far from qualified to explain it well...
"The branching behaviour is inherent in the Schrödinger equation."
The point is not the branching per se, but what happens in the current branch's evolution. There are only some branches that are 'legal' or 'likely', and it appears the limits/probabilities aren't deductible from Schrödinger alone. Almost like MWI needs a little extra something to be a complete theory.
P.S. That downvote wasn't mine.
https://www.lesswrong.com/posts/9cgBF6BQ2TRB3Hy4E/and-the-wi...
Edit. Based on Hossfelder's & Palmer's paper I have transitioned from MWI to superdeterminism. I encourage all to read the paper.
Very beautiful clarity of thought, I say.
Let's assume MWI is correct. This means that, as far as I understand, the Schrodinger equation imposes that for each quantum event there is a forking in two worlds: one per possible state (cat alive/dead). The implication is that there are (infinitely) many world branches that go from the beginning to the end of time. Since there is no collapse, each of these branches must be superdeterministic by definition: that's how we picked the branch, we identified a sequence of forks in the Schrodinger equation by picking the result.
"I" can live only in one of these branches: there are infinitely many "I"s, but the one I am in right now is one of them. I'll be in my branch until I die (many other "I"s will branch off me). Since every "I" lives on a branch, every "I" experiences the universe as superdeterministic. Thus, if we assume MWI is correct, the result for any possible "I" is indistinguishable from superdeterminism.
It gets funnier. If what I said it is true, MWI and superdeterminism are indistinguishable. However, one presupposes the creation of branches, while the other does not. Thus one is more parsimonious than the other, and should be preferred. Or, in other worlds, by assuming MWI is true, we prove that it is false and that superdeterminism is true.
My defense would be that, given that we picked a given branch from Big Bang to end-of-time, technically we picked a branch that had encoded all results of all forkings in the beginning, which is my understanding of superdeterminism. But as I said, I know too little about this to marry any opinion.
Like Copenhagen?
AFAIK, both explanations have been around for roughly the same while now, and neither seems to be going out of fashion any time soon.
My problem is probably not just a lack of math, but a lack of taste.
The fact is, we don’t have enough evidence yet to decide one way or the other, but there is a commonly accepted interpretation that is quite strongly cemented in the minds of practicing physicists, which works well for their purposes. When challenged by a fringe group, they will naturally defend their beliefs in ways that are both scientific and human-reactionary.
Being scientists, they will be open to changing beliefs given enough evidence, but being human, they will instinctively defend their existing beliefs, even if poorly supported, until sufficient evidence arrives.
I suppose the perfect Bayesian physicist would hold a superposition of beliefs, and use this set to decide on the most promising allocation of research resources. Of course, having incomplete information, there is always the chance of a hidden dynamic that, to uncover, requires chance investigation of an unlikely theory. :-)
The limitation of causation to a constant speed is well proven in experiments, and seems to be a fundamental aspect of the universe at large scales. If this same limitation doesn't hold at small scales then either:
1. There must be some cutoff between large scale and small scale, and small scale events can't influence large scale events. 2. Instantaneous action at a distance exists at large scales as well, and so our theories are wrong (we need a new theory to explain the observations of the speed of light etc.).
This is all not to mention that we have not noticed any particle moving past the speed of light, and that we have measured the same constant speed of light at quantum levels as well (a photon measured from a moving detector has the same speed as one measured from a static detector).
So that way lies nothing good. On the other hand, rejecting local realism doesn't mean that QM rejects the speed of light being constant - quantum entanglement can't carry information, so it can't produce actions at a distance.
Also, note that the most common interpretation of QM is neither local nor 'real' - that is, it implies both that particles have no definite state until they are measured, and that QE propagates at infinitite speed. That is, when you fire two entangled photons, neither of the photons has any value for polarization until they are measured; however, when one is measured, it acquires a particular spin, and the other one also acquires the corresponding spin instantaneously, possibly on the other side of the galaxy.
Now, one problem with all this is that it is extremely non-intuitive, and does not apply to the large-scale world (an apple is red whether I look at it or not). Related to the second issue, there is the problem of measurement: in a theory which rejects realism, the act of measurement has a fundamental physical effect, but there is no explanation for this mechanism, it is simply postulated. Note that a photon interacting with another photon is not measurment, they will each retain a superposition of states until a measurement happens.
What I don't get at all is the bit about quantum entanglement not carrying any information. Apparently, that has to do something with the fact that the collapse of the wave function is a random process? But, if you have probability then you have information, yes? What's the explanation?
What do you mean by that?
Suppose you and I are far apart in space and are each going to toss a coin, but we somehow magically know that one of us will get heads and the other will get tails. Can we use this pair of magic coins to communicate information? Actually no.
But even if you are the second one to do the measurement, and the particle has already acquired the definite state because of the other measurement, you can't tell that your measurement result was already guaranteed, since you can't perform another one on the same state to compute the distribution.
Perhaps quantum states obey the relationship closeness, not the arithmetical one. Classical physics obeys "arithmetical closeness" meaning that small differences in dynamical properties are close in state-space. But actually this is an emergent property: highly sensitive quantum experiments reveal that small differences in dynamical properties can be highly separated in state-space.
Rationals are all pretty easily related, but pi has nothing in common with a random close transcendental neighbor.
More: https://en.wikipedia.org/wiki/Implicate_and_explicate_order
If that really is the right way to think about the world, then absolutely nothing of science can survive. There is no such thing as a controlled experiment.
I don't understand how Euler's formula establishes a special relationship. You can compute a function of any two numbers. Where f(a,b) = a^{ib}, then f(e,pi) = -1, but why is that more meaningful than the fact that pi + e = 5.85987... ?
In Euler's formula in particular, the value e cannot be changed -- a complex number is necessarily represented as r * e^{iθ}. (Step one in processing e.g. 3 * 7^{i√2} is to normalize it to 3 * e^{i√2 ln 7}.) Pi is the angle between the vector (1, 0) and the vector (-1, 0). You could change that, and you'd have an equation saying that, if you rotate a unit vector by whatever the new angle is, the result is a complex number of unit magnitude and the angle you specified. For example, e^{2i} = cos(2) + i sin(2) = -0.416 + 0.909i. But I think the claim that this shows a deep, fundamentally special relationship between e and 2 is a hard sell. The cleanness of e^{i * pi} = -1 isn't telling you that pi is related to e -- it's telling you that pi is related to trigonometry.
e and pi are special too; nobody's questioning that. But they're not related to each other.
Consider correlations. A correlation is necessarily "transitive" if the correlation values are very, very close to ±1, and not otherwise. If a correlates with b at 0.7, and b correlates with c at 0.68, the correlation between a and c might be 0.69, but only by coincidence.
Reality owes us nothing - not even simple laws of physics.
Occam's razor is a pragmatic (human) bias - reality needs not adhere to it.
In fact, if reality adheres to Hickam's dictum then Occam's razor is an outright error.
For example, suppose I am betting with you on the outcomes of a coin toss. You call heads, the coin comes up tails, you give me some money. You call tails, the coin comes up heads, you give me some more money. This repeats a number of times.
The common sense response is to start suspecting that I am rigging the game, i.e. that the simple model of the coin flips being independent and random is wrong. The superdeterminist response is to say, "no, your guesses have been superdetermined to be all wrong by the initial conditions of the universe -- keep on playing!"
You can use superdeterminism to explain literally anything (not merely a lot, but actually, literally everything) while gaining precisely zero insight into what is actually going on, and precluding any future insight. Sure, it fixes a few philosophical problems, but so does saying you're a brain in a vat; in both cases you throw out all of science as a side effect. While their paper does address some philosophical objections, it doesn't even mention this scientific objection, which seems far more severe to me.
The wikipedia page on superdeterminism starts out:
"In quantum mechanics, superdeterminism is a hypothetical class of theories that evade Bell's theorem by virtue of being completely deterministic"
Logically, something that is "completely deterministic" would have to be...deterministic, no? Does superdeterminism go to 11?
To continue with the coin flip analogy, consider a classical world where a coin flip is perfectly deterministic, given the initial conditions. In the usual way we think about determinism, it's still possible to test whether a coin is fair. Just flip it a bunch of times, a little differently each time, and see if you get a ratio close to 50/50. That's standard science.
In the superdeterministic view, you don't admit this kind of explanation. Instead you say that whatever outcome happened was determined by the initial conditions of the entire universe. If you get all heads, you can't say anything about the coin -- we merely conclude that your hands were predetermined to give it the kinds of initial conditions that would have led to that outcome.
Now imagine repeating an explanation like this for every experiment ever performed. It's on the level of answering "God did it" to every question. We don't do that in science because it kind of defeats the whole point.
And saying that it is random with "God rolled a dice" isn't? The entire universe could have used a fixed random seed and our experiments and thoughts would have been exactly the same for all we know, determinism doesn't have the effects you talk about. We perform trials and do statistics when we don't know the exact workings of things, not because we believe that the thing is inherently random.
> To continue with the coin flip analogy, consider a classical world where a coin flip is perfectly deterministic, given the initial conditions. In the usual way we think about determinism, it's still possible to test whether a coin is fair. Just flip it a bunch of times, a little differently each time, and see if you get a ratio close to 50/50. That's standard science.
Every person understanding determinism will assert if you can repeat the same conditions of a previous coin flip, you will get the same outcome of the previous coin flip (for the next flip) and until the conditions are altered to make it so. The "conditions" being all the "external forces" acting upon the coin as it flips and lands.
We all understand a coin flip is 50/50 for us, since we're not perfect machines at replication. We would need to be able to analysis how to flip a coin the same as a previous flip and manipulate the environment of the coin flip to the previous flip if required.
The foregoing understanding is beneficial for scientists when it comes to experimentation. I understand why people can assume "God/Nature did it" would be worrisome. I still think you're making a big leap with what you originally asserted.
When choosing Superdeterminism as an ontology it suggests different paths for doing research, paths that are unexplored and potentially full of insight. That's what is exciting about it to me.
If we found hidden variables to control when a radioactive isotope will decay we could possibly have much safer handling of fission materials, depending on what these hypothetical hidden variables are.
* I don’t have an opinion on Superdeterminism, I’m just thinking about hypotheticals out loud.
If Superdeterminism is correct than it wouldn’t be up to us if we continue to experiment. Maybe we are compelled to try to understand the world.
In a dumb "the universe in a computer" metaphor, it's saying that instead of having `do_quantum_thing` be a function taking various physically interesting parameters and then resolving to something interesting (and thus making QM be _about finding that_), we just have a huge array like `result_of_all_quantum_things_ever_to_exist` filled with random garbage.
It's a theory that precludes any notion of predictivity in effects. It's nihilism for physicists.
The paper replies with the following argument: in super-determinism, statistical independence is an emergent property which holds at macro scales, so classical experiments do enjoy statistical independence. In your hypothesis - yeah, the game is rigged!
But superdeterminism comes into play at the quantum scale where we know things are already kind of fucked, which is why we're talking about this at all.
The idea is that God places Her thumb on the quantum scale alone. You might try to foil Her with an experiment exquisitely sensitive to a quantum measurement: the cat lives or dies according to the millionth decimal place of some measurement. But actually "cat lives" and "cat dies" might be very close in state-space - in the sense that two arbitrary real numbers might have some arithmetic relationship which cannot be proven (Chaitin's incompleteness theorem).
> But superdeterminism comes into play at the quantum scale where we know things are already kind of fucked, which is why we're talking about this at all.
But experiments already do use classical (i.e. macroscopic) sources of randomness. For example, to oversimplify a little, you might literally flip a coin to decide the specific measurements done in a run of a Bell test experiment. Such experiments still give puzzling results, so if superdeterminism is to work as an explanation of anything at all, it must hold all the way up. Superdeterministic explanations have to apply even to things like coin flips, which, again, leads to the end of science, wailing and gnashing of teeth, etc.
It would be the end of the current interpretation of what science means, but the process and results of science could carry on as they always have.
There is also the glimmer of post-science, in which we might be able to find a process/method that is more effective/efficient than the scientific in some domains.
And you’re right — there will certainly be wailing and gnashing of teeth. :-)
Err, whether you "keep on playing" or not, would also part of it.
Besides, lacking a source of actual randomness (even non superdeterminist QM doesn't provide one), plain on determinism seems plausible even without needing to explain quantum mechanics. Besides if we did had a source of randomness it would still be just randomness.
Where would "free will" come from (it being something different than randomness, essentially an agent non-determined by the prior state of the universe nor one's prior history, making decisions inside one's head).
I may be totally off base but my understanding is the analogy is more like Craps. Two dice with fair odds create an uneven distribution such that 7 is more common. The dice have "conspired" to bring 7 up more often than 2 because their states interact in a non-linear way.
The point is that Bell's theorem relies on the assumption that a linear distribution must be expected and the paper is arguing that that has not been sufficiently proven. At least that's my understanding of the paper's argument.
>With the measurements oriented at intermediate angles between these basic cases, the existence of local hidden variables could agree with/would be consistent with a linear dependence of the correlation in the angle but, according to Bell's inequality (see below), could not agree with the dependence predicted by quantum mechanical theory, namely, that the correlation is the negative cosine of the angle.
Also keep in mind we don't observe linear correlations - at least one of the assumptions of Bell's theorem must be wrong.
Here is a more appropriate analogy. Suppose I'm playing a shell game with you and you have to guess where the prize is. You guess the wrong position a million times in a row. Something analogous to this happens when we try to test quantum mechanics. Other interpretations of quantum mechanics explain this by saying, e.g. that the prize doesn't have a definite position to begin with, so the act of checking where it is can't be interpreted as just revealing a preexisting fact. The superdeterministic explanation is: "well, there's nothing to explain. You were simply determined to lose by the initial conditions of the universe. It couldn't have gone any other way."
What? It's like the opposite...
Currently we don't have a perfect model for quantum physics, so what do we do when we try to create a model of something where we have data for, but we don't fully understand? We use statistics and probabilities to fit/approximate the behavior behind the model. Doing this can lead to a useful but imperfect model, but that doesn't prove one way or another that the behavior of what we're trying to understand is inherently random, just that it exhibits random behavior at some level or in some way.
Now the opposite: saying things like Heisenberg's uncertainty principle is full stop proven, is itself a stop sign for thought IMO. Whereas opposing such principles, and assuming behavior isn't inherently random (i.e. the idea behind determinism), opens for testable ideas on what might actually happening behind the apparent randomness of the model. You know... one which might lead to a perfect model fully explaining the behavior (which hey isn't that the purpose of science??)
To put it backwards... the ideal in science is a model that explains how everything works, if this is ever realized it'll prove superdeterminism. To say stuff is inherently random, to me is equivalent to giving up and settling for less than the ideal...
There are explanations for measurement. Not everyone agrees with any single one of them, but they definitely exist. Superdeterminism is one, but it's not the only one. It is really only the Copenhagen Interpretation of QM that has a measurement problem.
Personally, I am on board with the "measurement is just entanglement" solution (it seems intuitively obvious to me, but then I'm sure superdeterminism seems intuitively obvious to those who believe in it as well), which makes superdeterminism unnecessary.
You, however, being a large, warm thing decohere rather rapidly, even if the formal measurement apparatus can be made not to. Your consciousness is a classical phenomenon, so you can only perceive one possible classical outcome. If you believe in Many Worlds (which is the most natural interpretation to pair with this resolution of the measurement problem, but is not absolutely forced), then there are other versions of you out there in different parts of state-space which perceive different outcomes, and may even be observable as elements of a superposed-you in principle if not ever in practice, but there is no means of transferring information between any of these different versions of you.
EDIT: To whomever downvoted the parent... why? It is, after all, a perfectly reasonable question, especially (although I do not presume that knzhou personally holds this view) in light of the reasonably common assumption that consciousness is somehow quantum in nature itself.
That is, if "worlds" branch off with some amplitudes, and there's a "me" on this branch and another on that branch, how does it make sense to talk about the probability of "me me" being this one or that one?
Empirically we know how to calculate it from the amplitude, but why is that more reasonable than any other answer (if any answer is reasonable)?
Yea, there is still work to be done at a lower level, and there are other competing explanations at this level, but that doesn't mean that we don't have an explanation at this level. "How does the Born Rule work?" is a lower-level question than "how does measurement work?"
I guess you could say that MWI removes the wishy-nastiness around what constitutes measurement, when it happens etc, and that could constitute "solving the problem", but I think
- Some of "the problem" has just been moved outside those borders. (And fine -- the MWI doesn't need to solve every problem to be an improvement. And I do think it's an improvement.)
- The Born Rule is weirder* in the MWI. In Copenhagen it's axiomatic: We explicitly roll the dice, a nondeterministic outcome happens, that's the mechanism. In MWI it's an afterthought: The wavefunction evolves deterministically, and oh-by-the-way you should weight the likelihood of finding yourself here or there by the squared amplitude.
Maybe that's unfair though?
Now go compute what happens when, instead of feeding classical trial results into this computation, you feed in a series of qubits each in the state a|0> + b|1>. You will find that the output register ends up storing a state extremely close to the representation of the probability |b|^2, up to some precision limited by the number of samples made available to the inference process. This indicates that "almost all the branches" must be agreeing on this particular value as the probability. That's the sort of way in which quantum mechanics, minus the Born Rule, predicts that almost all agents embedded in a quantum world will conclude that it follows the Born rule.
I fire a polarised photon at a polarised filter oriented 30° off. In Copenhagen there's a 75% chance it goes through, and a 25% chance it hits the filter. In MWI there are two branches, one with squared amplitude of 0.75 and another with squared amplitude of 0.25, and there's a "me" on each side.
Now, say I can bet on what happens at even money. In Copenhagen we'd say "betting on the photon going through is positive expectation." In MWI though, one of "me" wins and the other loses, and we just say "there's less subjective chance of being the loser"? Or "the loser has less amplitude, so less moral weight"?
I don't think it's super satisfying.
Does it provide a deductive argument for using the squared amplitude? Or does it just make use of the same empirical evidence everyone else uses, and actually not provide any explanatory power?
An example taken from another thread: Fire a laser of polarised light at a polarised filter angled at an offset of 30°. Measure the light on the other side of the filter and you'll see it's 75% as bright.
Now, you could say "We have worlds splitting independently for each photon that goes through or doesn't, and we're on all of those worlds," but that isn't explanatory -- it doesn't tell us why it looks like three quarters of the photons went through, as we always measure.
Then what is "entanglement"? I sure would agree that 'measurement' and 'entanglement' have a similar nature. I just think this argument doesn't answer the original question, but it is trying to hide it.
That is what "measurement is just entanglement" provides.
Besides that, there is one point I don’t get about many worlds and entanglement theories: assuming that “measurement is just entanglement”, there are many possibilities how the observer gets entangled with the wave function it observes. How is it decided which entanglement (or which world) is the one we actually observe?
When and how does that projection (which is non-unitary and otherwise ill-behaved) happen? What causes it to occur or not occur? How do you explain the results of the quantum eraser experiment, where the exact same physical process retroactively turns out to constitute a measurement or not depending on what happens in the future?
> Besides that, there is one point I don’t get about many worlds and entanglement theories: assuming that “measurement is just entanglement”, there are many possibilities how the observer gets entangled with the wave function it observes. How is it decided which entanglement (or which world) is the one we actually observe?
No, there is only one possible way to get entangled with what you observe. If you observe a spin-half particle that's in state (1/sqrt(2))(|up> + |down>), then afterwards the you-photon system is in state (1/sqrt(2))(|up>|you after observing up> + |down>|you after observing down>), exactly as if you were a normal physical object obeying the normal laws of physics.
The question you can and should still ask is "what should we expect the subjective experience of being in this state to be like". And to a certain extent, why the Born rule applies is still something to be explained (though I'm not aware of any alternative possibilities that would be well-behaved). But that's a much smaller and simpler question.
Measurements cause it to occur. What causes entanglement to occur?
> quantum eraser
Not sure how it works, but Wikipedia says that it can be explained using Copenhagen carefully.
> (1/sqrt(2))(|up>|you after observing up> + |down>|you after observing down>)
After the measurement I’m not in a superposition of the two entangled states but in one of the two, because I do observe the photon in a particular spin state. Which one is it? And how is it decided?
Ok, but what's the objective physical distinction between a measurement and a non-measurement?
> What causes entanglement to occur?
Various specific kinds of normal physical interactions, the details of which are an established part of QM.
> After the measurement I’m not in a superposition of the two entangled states but in one of the two
What would you expect to be different if you were in a superposition of two states?
> I do observe the photon in a particular spin state
Sure, because your state is entangled with its state. That's the normal, established behaviour of entangled states.
Various specific kinds of measuring devices the details of which are an established part of QM.
> Various specific kinds of normal physical interactions, the details of which are an established part of QM.
So, which is the interaction that causes entanglement? I was asking for this before.
> What would you expect to be different if you were in a superposition of two states?
Well, I would expect my measurement to also have all possible outcomes given by the superposition.
> Sure, because your state is entangled with its state. That's the normal, established behaviour of entangled states.
Only after a one of the entangled particles is measured. Either my brain must be measured or the result must be measured. In this sense entanglement doesn’t work without an ill defined concept of measurement either.
They're not though. There's no generally accepted definition of what is and isn't a measuring device. And, as per the quantum eraser experiment, the exact same equipment might be considered as a measuring device or not a measuring device, depending on what happens in the future.
> So, which is the interaction that causes entanglement? I was asking for this before.
The only fully accurate answer is "look at the Schrodinger equation". But, broadly, interacting with an object in superposition in a way that depends on that superposition will cause entanglement. For example, if a particle's spin is in superposition, another particle interacting it in a spin-dependent way will cause entanglement, but interacting with it in a spin-independent way will not create an entanglement.
I appreciate that this must sound exactly as vague as the definition of a measurement. But for those familiar with QM it really isn't. If you look at textbooks, even those written from a Copenhagenist point of view, they're very clear on which physical circumstances give rise to entanglement and which don't. If you go through any undergrad-level QM textbook you'll have a clear understanding of what entanglement is and isn't.
> Well, I would expect my measurement to also have all possible outcomes given by the superposition.
Ok, but what would the subjective experience of that look like?
> Only after a one of the entangled particles is measured. Either my brain must be measured or the result must be measured. In this sense entanglement doesn’t work without an ill defined concept of measurement either.
Not true. Just by looking at the wavefunction, one can see that the wavefunction is a superposition of two distinct Everett branches that don't interact with each other - not because of some mysterious "collapse" phenomenon, but just as an emergent property of that actual wavefunction. Finding yourself in one specific branch is somewhat mysterious, but each individual branch being consistent with itself and not interacting with any other branch is absolutely normal QM.
This doesn't explain the cause of entanglement. It just explains the circumstances under which entanglement occurs.
> I appreciate that this must sound exactly as vague as the definition of a measurement
That's because it is beyond the mathematics.
> But for those familiar with QM it really isn't.
This is not true. I'm familiar with QM and it is vague to me.
>they're very clear on which physical circumstances give rise to entanglement
But, none explain the cause of entanglement. Just as none explains the cause of collapse of a wave function which is called a measurement.
> Ok, but what would the subjective experience of that look like?
I wouldn't know, because it's not what can be experienced. Some folks argue this is exactly what makes many worlds unscientific.
> Just by looking at the wavefunction,
Interesting. What kind of microscope are you using to look at wave functions? Or do you mean at the mathematical expression of the wavefunction? I'm not arguing that decorherence theories are mathematically sound and a neat theory. I'm just challenging that they offer some physical explanations beyond Copenhagen. They just take the unexplained things and replace them with other unexplained things.
> emergent property
Another empty word.
> Finding yourself in one specific branch is somewhat mysterious
Yes. And if you think about it, this is the same mystery which makes Copenhagen so unsatisfactory, just put into a different framework.
"Entanglement" is just a term for a particular kind of behaviour that (some) solutions to the Schrodinger equation exhibit. I can't tell you why physical reality conforms to the Schrodinger equation, but I believe we're all agreed that it does.
> That's because it is beyond the mathematics.
No it isn't. It's right there in the mathematics.
> This is not true. I'm familiar with QM and it is vague to me.
With all due respect, if entanglement is vague to you then you're not familiar with QM. Entanglement is a basic quantum phenomenon and the results of quite simple experiments cannot be understood without it. You will find respected authorities on QM who disagree on interpretations, or disagree on how we should think about measurements. But you will not find any who disagree on what the phenomenon of entanglement is or when it occurs, regardless of what interpretation of QM they subscribe to.
> I wouldn't know, because it's not what can be experienced. Some folks argue this is exactly what makes many worlds unscientific.
Just the opposite: blithely asserting that you're not in a superposition, based on zero scientific evidence, is what's unscientific. Unless and until we can come up with some experiment that would distinguish being in a superposition from not being in a superposition, we should be agnostic about whether we're in a superposition, and have no particular reason to favour a theory that claims we're in a superposition over one that claims we're not (or vice versa).
> What kind of microscope are you using to look at wave functions? Or do you mean at the mathematical expression of the wavefunction?
If you're claiming that the wavefunction is a physically real thing then the Copenhagenists will kick you out :P.
> Another empty word.
Not at all; while it's a word that's frequently abused, it does mean something specific and well-defined.
> Yes. And if you think about it, this is the same mystery which makes Copenhagen so unsatisfactory, just put into a different framework.
I don't think it is so mysterious: if that mathematical description of reality is accurate, what else could we possibly expect to experience? To claim that subjective experience is messy and complicated is a much smaller assertion than to claim that this messy complication exists in objective physical reality, as the Copenhagenists do.
If this was true I would offer another theory: an untraceable Flying Spaghetti Monster is responsible for QM. You won’t be able to gather any evidence against it, so you cannot rule it out. This theory would be on par with your many worlds theory. I can also write down physically looking equations which describe its behavior.
I think the gist of science over religion is exactly the requirement to provide evidence for the claims it makes not evidence against opposing claims. Otherwise science is dogma.
Just the opposite: positing a collapse phenomenon which makes no difference to observable reality is on a par with positing an untraceable Flying Spaghetti Monster. Many-worlds is not an extra assumption but the absence of one: it's the assumption that we behave like normal physical objects, and all the normal, experimentally-established phenomena of quantum mechanics (such as superposition) apply to us just as they apply to other matter we experiment on.
Max Planck's Loader Model - the simplest interpretation that is never looked at.
In the Loader Model atoms have a hidden and random energy state, and a detectable state. The energy of light is spread evenly as waves. And when the energy reaches a threshold the detectable state changes. Photons do not exist. What we see are just detectable jumps of the energy states.
I never heard of it, until I found an experimenter that claimed to find evidence for it. With higher levels of energy than normal light, he found that (more often) two or more atoms can reach a next state, when one quantum of energy is emitted. Other experimenters classify these double-quanta as "noise".
Occham's razor?
Because it is the simplest interpretation, I would like to see more research into this. Maybe there is something to it, or maybe it can reveal some hidden variables in the detectors.
See: www.threshodmodel.com
Note: the experimenter is not a very good communicator and it took me some time to understand what he was explaining.
Because the experiments and theory are so simple, I think it is the most scientific approach, to at least test this Loader model more thoroughly. Even if I don't agree with it. ;-)
It is actually the only explanation that is consistent with experience, since there is no experience outside of consciousness.
That’s a silly statement. How do we know that, if we aren’t looking at it?
But still, the number one unverifiable prediction is that there is a thing called matter that exists outside consciousness and that somehow, consciousness emerges out of it. Nobody can prove matter exists, nobody has ever had a direct experience of it, and nobody has any idea how consciousness could come out of it, yet it's still the default hypothesis…
It does not mean that there is nothing when no one is looking, just that what we see is a representation by our brain of something objective that we can't directly assess. The representation stops to exist when we stop looking. What part is representation and what part is objective is debatable.
Assigning more to the representation and less to the objective solves some problems neatly, like that of quantum entanglement.
Take Donald Hoffman's example of a cube drawn in perspective as lines on a piece of paper. In your mind you see a cube, but nowhere is there actually a cube. The front and back faces of the cube are entangled : if your mind has decided on the projection in which one face is the "front", the other face has to be the "back", and vice-versa if your mind has decided on the other projection.
"Spacetime is doomed. There is no such thing as spacetime fundamentally in the actual underlying description of the laws of physics. That is very startling because what physics is supposed to be about is describing things as they happen in space and time. So if there's no spacetime, it's not clear what physics is about." - Nima Arkani-Hamed Cornell Messenger Lecture 2010.
Deepak Choprah is clearly not the right person with which to discuss such things, and debating him is just Sam Harris being full of himself or a publicity stunt, not an actual serious look at these ideas.
A real external world is perfectly consistent with us not experiencing anything outside of consciousness, that is, that our consciousness is how we experience what we experience. There's still something out there - an external world - that we experience, though.
The alternative way of taking your words - that there is no external world at all, that all we are is consciousness, that we aren't actually experiencing a real world - is the total death of science, because there's nothing actually there to study.
I think it's reasonable to assume that an "external" world exists, but it doesn't mean that it's not all consciousness : as Donald Hoffman posits, what we perceive is the combined output of other conscious agents. I don't see how that means the death of science. I suppose you meant physics, which could indeed be seen in this context as a rather convoluted way of studying consciousness, but I'm not so sure : it would become a study of the regularities of consciousness.
In that light, photons (and to a lesser extent, the other gauge bosons) play a significant role in theoretically calculating the dipole moment of the electron (how strong the electron interacts electromagnetically) which has been calculated to about 12 decimal places theoretically and experimentally measured to roughly the same precision. And the prediction fits _beautifully_, I believe it is the most (numerically) accurate prediction in all of science. So at the very least, photons are meaningful descriptions of some kind of quantum field oscillation whose existence is, implicitly, extraordinarily well determined.
Typing this in a rush, but just to say, photons are a very specific kind of energy quanta, and I don't think the loader model really replaces them in that sense.
The "accuracy" is probably the same, depending on how the experiment is setup. Even a standing clock can give the accurate time, once a day. ;-)
But, the experiment that are directed towards detecting this variant, show that the Loader model is valid... due to double detections of quanta, when there should only be one. According to the experimenter that I linked to, with easy-to-repeat experiments.
So Occham's razor tells me to look into it, before starting more complicated theories. It is not my favourite theory, but I am a scientist.
I had a small discussion setup here. Feel free to add a comment. https://saidit.net/s/Physics/comments/18rz/nullhypothesis_qu... (saidit is a friendly community for open discussions)
Always been a fan of Superdeterminism, happy to see actual physicists working on it.
Show, don't tell. I don't know how things work in physics (maybe they need a grant) but in mathematics, if you make a ruckus without any actual mathematics, then people ignore you. If you have a proof or text that does something substantial, then people do ignore you at first but in the long run the best mathematical base of knowledge takes preference.
> Cough.
My favourite crackpot sent her his theory about gravity because she published a bimetric model of gravity a decade earlier. She accused him of plagiarism. Full story (french, bad subtitles): https://www.youtube.com/watch?v=CKWqh75ErNI&t=40m54s
Also she made a few music-videos (the music is her own it seems):
1: Untriangulable smooth manifolds exist.
2: The manifolds can be smoothed via Ricci flow in a manner similar to how Perelman solved the Poincare conjecture.
3: This smoothing, applied to an untriangulable manifold, is irreversible, deterministic, and yet somehow must not converge to any triangulable manifold.
Even the comments on the blog post seem exceedingly cranky. I can imagine it's very hard to work in such an area, with such a noisy peanut gallery.
I mean he wrote Perelman’s name so he must be onto something.
The manifold cannot, in whole, as a result of this, get "simpler" or even maintain the same amount of simplicity, it must somehow get more complex, which would require information to be generated. The primary problem with deterministic models, at least as I understand it, is that there's no obvious way for deterministic processes to get more complex.
People who study the fundamentals of quantum mechanics complain that philosophy is seen as useless. From my understanding this stems from how in detail the Copenhagen 'interpretation' took hold in particulary U.S. institutions; and it is entirely non-scientific. Copenhagen is an engineering discipline, and not a scientific theory. In natural philosophy we have to account for our position compared to the object we study. We are not separate from nature.
Philosophy has many ideas which help us deal with our physical reality and they need to be taken seriously.
This would be a terrifying revelation on a personal and existential level.
I've encountered a few people that will cite quantum theory when it comes to discussions about questioning if one has free will. I cannot even imagine how quantum theory gives a us true free will and without one's will just being the outcome of the system we reside in.
Now go back to step one and assume that, even on an atomic level, there is no chance, no randomness. Given all of the preconditions, we get this outcome every single time. Then I have to reconsider why is there even the illusion of choice. Why should I even write this comment. It’s crazy.
I think the answer is society conditions us to assume we have choice by how society is structured and how society functions. You writing the comment is just me being an external force upon you and triggering it from all the previous external forces that made you eventually react the way you did. Even if everything isn't random, a lot of what people like to wish for & believe, can in fact come true but it's hard for me to rationalize it. Other than an outside our universe deterministic observer needing to exist.
Personally, fundamental randomness is more disturbing to me because it implies a-causality, i.e. that at the smallest scales things happen for no reason at all and would be unexplainable in principle.
Why is that? I believe the universe is fully deterministic (i.e., no such thing as "true" randomness), yet I also don't think that rules out free will. Free will and determinism aren't necessarily incompatible.
How?
The opposite, non-determinism, means that your decisions aren't fully determined by your own past and experiences, which to me sounds like a greater violation of free will.
Under the standard definitions, they are; if will is strictly determined by other material facts, it is not free. If you adopt unusual definitions for one or the other, they may not be, but then you aren't talking about the same thing other people are when you use the terms.
Anything that makes believers in Free Will or Consciousness unhappy makes me happy.
Unlearning that — understanding that this model is one interpretation, but not the only interpretation — is indeed terrifying and exhilarating. I personally wouldn’t call my experience “not conscious”, but it can be a very different experience than what we consider normal everyday waking consciousness.
So these other humans in the world are probably just deterministic robots just like me, that may or may not feel like they have magic conscious aliveness.
But my personal experience tells me that I can turn the “sense” of magic conscious aliveness on or off, and so it too is likely just a neural process that is not particularly interesting.
I observe that the vast majority of other humans do not seem to be able to disable this sense at will, which does not to me imply that they are somehow more magically conscious, just that they have not experienced that particular switch flipping.
Add in the historic social knowledge of “consciousness”, the historical record of neuroscience knowledge, and the rates at which scientific knowledge is processed and absorbed by the public at large, and it really seems like an obvious non-problem.
I have not ever seriously considered the ability to turn consciousness on and off at will. In my experience consciousness is absolute and once deep in reverie when I happened upon a mental switch to turn seemingly everything off I instead experienced a brief 'no-mind' blank state and a moment later my mind basically 'rebooted'. During no-mind, "I am" was definitely there but there was no thought to reflect this fact. There was an observer with nothing to observe. Normally, the only interruption to consciousness that I experience is for the time between wakefulness and dream and for this period I have no recollection.
Is this no-mind state what you mean by turning off consciousness?
I mention this particular state because it seems to reveal that the feeling of being an agentic self is a specific construction of mind, and that it can be intentionally deconstructed while maintaining other brain functions.
There are lots of related directions one can go with this; the “no-mind” state you mention and the techniques to achieve it are excellent to practice with.
Ascribing to new theories doesn't change the world at all, they can only change your understanding of how the world already existed.
Consciousness is certainly less unique in this interpretation but I'm not sure that means its so uninteresting that we must say a rock is conscious.
That said, I think the OP is conflating free will with consciousness which I think is a mistake. I think its more useful to keep the definition of consciousness as only a sense of self. Even if universal determinism does not exists, one could imagine an AI built in classical physics that exhibits a sense of self deterministically.
Obviously we all experience what we call consciousness, noticing ourselves noticing, and we all imagine we have free will, which really only means we don't know what we will do tomorrow.
But neither of those have anything to do with physics, except to the degree that the stuff we are made out of runs according to physics.
So, anybody supposing that either concept has anything to do with quantum physics is barking up something that is not even a tree.
The tools of physics are developing and while working out the kinks of the standard model a new set of tools are emerging. These tools deal with information and complexity. The boundary between the terms 'entropy' of CS and physics is blurring, and decoherence is a physical information process. Many ANN research papers that I have read use concepts familiar from physics.
Why would there exist separate realities for information processes, consciousness, and physics? Personally I think that consciousness is inseparable from physics and it makes no sense to say that one precedes the other. I think our minds simply notice a universe of consciousness and our confusion comes from adding retrievable memory on top of it. I challenge anyone to come up with a simpler explanation...
I reason that since a process which is described by the same mathematics gives rise to the mind, then with a slight tweak it will give rise to something else. Since consciousness is close at hand I plug it in and try to see if it fits.
"People are capable of random actions they can't control so they have full responsibility of their actions."
"Ability to do some action without a cause, but not able to choose that random actions makes me free from the rest of the universe."
"Most importantly, we will discuss how it may be possible to test this hypothesis in an (almost) model independent way."
Most. Importantly.
Then in the paper, under "Experimental Test":
"This means concretely that one should make measurements on states prepared as identically as possible with devices as small and cool as possible in time-increments as small as possible.
This consideration does not change much if one believes the hidden variables are properties of the particle after all. In this case, however, the problem is that preparing almost identical initial states is impossible since we do not know how to reproduce the particle’s hidden variables. One can then try to make repeated measurements of non-commuting observables on the same states, as previously laid out in [36]."
And finally:
"[36] S. Hossenfelder, “Testing super-deterministic hidden variables theories,” Found. Phys. 41, 1521 (2011) [arXiv:1105.4326 [quant-ph]]."
So after the "most" qualified introduction, eventually just a reference to her 2011 paper. "Most importantly" "good" ... joke?