Good point and perhaps the only way to resolve it is to assume ‘consciousness’ is a permanent feature of reality, in one form or another. In fact, consciousness must be infinite, otherwise how could it get going in the first place?
You see, you have highlighted the problem with making models of reality. A model might answer a number of questions but looked at from a new perspective leads to contradictions. Well done.
No, don’t refute it. Just realize it is indicative of something much deeper. 
Penrose is a wise man and realizes we can never come up with anything definitive and in no need of a re-think. Science is a* process*.
But whatever weather is happening on any of the planets (including this one) is happening - sure - but we have the weather happening on its own, with no observers, and weather happening with us observing it. These are not quite the same thing. We still have to use our sensory equipment to ‘track’ what is happening to the weather so you’re introducing a new element into the overall system. Again, this is exactly what happens in QM experiments. In short, whatever is observed disturbs it and those people here who can’t seem to grasp this and insist stuff goes on whether we are involved or not seem to be missing the point, it seems to me. You can never see nature (or reality) in its ‘pure’ state.
You know in the best way you can.
I think you’re confused about the meaning of positivism. In positivist philosophy, ultimately, only empirically sourced statements are supposed to have meaning. Thus, physics doesn’t ever concern the way the world is, but rather, what we can say about what happens when we perform certain experiments. In this sense, the still most widely popular Copenhagen interpretation is essentially positivist.
Moreover, the idea that experiments could cast doubt on an interpretation is mistaken: if they could, we wouldn’t have alternative interpretations, but competing theories, with the experiment deciding between them.
The real problem with (logical) positivism is, of course, as A. J. Ayer (one of the most prominent figures of the movement) put it, that nearly all of it was false.
There are two main ways of thinking about the wave function, known somewhat cumbersomely as psi-epistemicism and psi-onticism (or, to some of its detractors, psi-ontology). The former postulates that the wave function is an element of knowledge, an element of our description of the world, like, for instance, a probability distribution in a game of chance that has an underlying deterministic description. The latter consequently proposes that the wave function is an element of reality, something independent of our minds, out there in the world.
Importantly, even if the wave function is ‘all in our heads’, so to speak, that doesn’t allow us to infer that ‘our minds shape the world’, exactly because the wave function is all in our heads: it simply doesn’t license us to derive any metaphysical claim, since that would be a claim about what the world is like, but if the wave function is just an element of knowledge, then there is no guarantee that it allows any conclusions about what the world is like.
There could, for instance, be an underlying, fundamental layer simply inaccessible to us (cognitively or empirically), and the wave function is merely some sort of ‘average’ description of it; but then, the change of the wave function upon measurement does not tell us anything more than the change of the probability distribution once we find out which way a coin throw comes out (from ‘50% heads, 50% tails’ immediately and discontinuously to ‘100% heads’, say). There are models implementing such dynamics.
And again, psi-epistemicism is essentially consistent with positivist philosophy, telling us, Bohr’s words, that physics doesn’t concern how nature is, but merely, what we can say about nature.
Interestingly, one can put some assumptions on how a psi-epistemic theory could be supplanted by a more fundamental one, and then show that quantum mechanics disagrees with the predictions of such theories—which has been taken as a strong argument in favor of psi-onticism (this argument is known as the PBR-theorem). This would mean that the wave function is something real, out there, and independent of human minds (although of course, there are assumptions that go into the theorem that can be, and have been, questioned).
But in the end, neither option suggests that ‘our minds shape the world’: if the wave function is all in our heads, we simply can’t say anything about the way the world works—only about how we describe it; if it’s out there, it’s plainly independent on what’s going on in here.
I presume you’re talking about the various versions of the quantum delayed choice experiments here. It’s true that popular-level treatments often exacerbate their spookiness, but, if you go right down to the nitty gritty, they’re really not so puzzling at all. I’ve posted a more detailed discussion of this experiment here; but the basic gist is that you don’t ever see an interference pattern, at all, using only locally available information—it’s only if you correlate that information with information obtained at far-away detectors, essentially ‘throwing away’ a certain subset of events, that a pattern may emerge.
This is not true: there are many interpretations (in fact, the vast majority of interpretations) in which the observer plays no role at all in QM; and even in those where the observer does play a role, that’s not generally the one you ascribe to it—for instance, the observer plays a role in QBism, but really only because QBism doesn’t hold quantum mechanics to be a description of the world as it is, but more of a manual for how we can interact with the world, whatever that ‘world’ may be. It’s only really on Wigner’s ‘Consciousness Causes Collapse’, and some versions of Copenhagen, that the observer has such a role.
Again, this isn’t right: Bell showed that a particular class of hidden variables is incompatible with quantum theory—those that don’t influence one another instantaneously across arbitrary distances—but in fact, Bell himself was one of the staunchest proponents of a hidden variable theory, namely, Bohmian mechanics (which, of course, includes nonlocal influences). BM continues to be viable today, reproducing all predictions of quantum mechanics.
Saying ‘consciousness works in mysterious ways’ suffers the same problem, however.
While it’s correct that consciousness doesn’t play a role in measurement, it’s not quite right that particles ‘observe’ one another: when they interact, they will typically enter into an entangled state, which is a superposition of states of the two-particle system, and not a combination of definite one-particle states, as one would have post observation. Indeed, we know that this doesn’t work: otherwise, we wouldn’t observe Bell inequality violation.
So there is a real measurement problem—since obviously, one can just extend this sort of reasoning to collections of arbitrarily many particles, and a detector just is a collection of many particles—but it doesn’t imply that we have to resort to exotica brought in by ‘conscious observation’ to solve it. Indeed, the problems introduced by postulating such a solution seem much greater than those one hopes to solve in the first place.
But what’s a ‘detection mechanism’? In the end, just another quantum object. But then, how does the system know when to collapse the wave function?
*There are more things in heaven and earth, Horatio,
Than are dreamt of in your philosophy.
*
Thank you for this interesting and useful post, GreenWyvern. I tend to “materialism” myself, but try to keep an open mind.
Those guys were men of their times. None was born less than 110 years ago, and all but one were born in the 1800s. Saying something like “God is the Universe” (which I’ve said a few times myself) is just another way of saying we don’t know what the universe is, and probably are incapable of knowing anyway. And the idea that things are easier to explain if “God did it”, well tell me exactly why that is since it just adds another thing into the equation that is at least as difficult, if not more so, to explain.
John von Neumann; born 1903
Niels Bohr; born 1885
Max Born; born 1882 (heh!)
Erwin Schrödinger; born 1887
Max Planck; born 1858
Is he now. :rolleyes:
By the way, for a good, non-woo introduction about what, if anything, quantum mechanics may tell us about the mind, and what our experience within the world may tell us about QM, I can heartily recommend David Albert’s Quantum Mechanics and Experience, and Jeffrey Barrett’s The Quantum Mechanics of Minds and Worlds. I’d suggest reading them in this order, as the latter is in some ways a sequel to the former, and Albert’s book in particular is a fairly gentle, though not completely non-technical introduction to its subject.
(Although really, Barrett’s book is more about many worlds- and Everett-type interpretations.)
By claiming an absolute. Uh, yeahrite.
There are two possible things you can say with exactitude:
a) That you believe that something is unknowable (a cop-out of Trumpian proportions to my eyes), or
b) At this point, based on your necessarily limited knowledge-set, that you don’t know it.
Maybe I put it clumsily but what I meant was we can only deal with the models we construct as a result of experiments and consequently, to claim we really know what is going on is false, as you have pointed out. You’re really saying what I was saying but when I said positivism cannot explain reality what I was really saying is we are left with our ‘subjective’ version of it.
Oh, I agree, but the fact is that none of these interpretations can be considered to be a materialistic version of reality, something, it seems to me, some scientists want to cling onto in a bid to retain traditional views about reality. If you check back and look at some of the posts made here you will see an outright rejection of some of the interpretations concerning the results of QM data.
But again, you are being selective. You can always just look at certain elements in an experiment that exclude the totality of the situation but that seems to me to be censoring what the overall effect is. It’s like conducting a survey and throwing half the answers away because you wish to present a certain interpretation. The point here, it seems to me, is that the knowledge held in an observer’s mind is contributing to the odd effects seen in such experiments and focussing on just one part of it would appear to be limiting that knowledge. Surely the thing to do is consider what is happening overall, not at ‘bits’ of the process.
This is saying that the same processes occur when there is no one about as do when an observer is present. Unless you can show something other than a reasonably sophisticated observer is able to ‘observe’ it makes no logical sense. You are forgetting that the observation made by a human being is only produced by a combination of whatever the phenomenon is doing in combination with the processed data that has to pass through human consciousness. How could that possibly be equivalent to, say, a stone ‘observing’ what is happening? What exactly would the stone observe?
I think you are in error there. There is no need to postulate for hidden variables, local or not and Bohm was shown to be wrong. Bell has shown that locality is a myth.
Saying ‘consciousness works in mysterious ways’ suffers the same problem, however.
While it’s correct that consciousness doesn’t play a role in measurement, it’s not quite right that particles ‘observe’ one another: when they interact, they will typically enter into an entangled state, which is a superposition of states of the two-particle system, and not a combination of definite one-particle states, as one would have post observation. Indeed, we know that this doesn’t work: otherwise, we wouldn’t observe Bell inequality violation.
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It depends on what you mean by ‘observe.’ Okay, perhaps I used the word loosely to mean particles are somehow ‘in touch’ with one another (which they must be to know when one or other of them has been measured) but then one could say we observe particles observing themselves. I mean you seem to think that all this goes on when nobody is conducting a scientific experiment! It can’t because by ‘looking’ we are influencing the condition under which all this happens. This is the ‘elephant in the room’ and it needs to be faced.
Because we are part of the overall ‘system’ that is orchestrating everything. We are not separate or isolated from the system but form a vital link in it. What you have said is very interesting but unfortunately you cannot prove any of it without the participation of an active observer. Surely that is evidence enough, is it not?
Thanks, placed an order for* Quantum Mechanics and Experience*. This is a great thread.
Nothing is absolute, just a temporary situation.
If you’re talking about evidence-based belief then sure, why not?
Everyone has limited knowledge. In fact, we have no knowledge of anything aside from what is in our nature.
This doesn’t follow: the models we construct may still track what goes on in the world. That’s the gist of the ‘no miracles’-argument for scientific realism: the simplest way to explain the success of our best theories is that they’re actually true; in fact, for them to be false, while still delivering this kind of success, would seem nothing short of miraculous—what is it that makes them successful, if not that they correspond in some way to what’s really out there?
Many interpretations of QM are materialistic in the strictest sense. Bohmian mechanics, Nelsonian statistics, Girardi-Rimini-Weber/Penrose-Diosi collapse theories all essentially don’t need any sort of departure from classical mechanistic or material notions. Neither do most many worlds-type interpretations, and for most others, the issue is debatable at best.
In what way am I being selective? What is it you think I ‘throw away’?
There’s absolutely nothing in quantum mechanics that implies that knowledge has any effect on experiment. There is, I grant, sometimes imprecise talk that could introduce such an impression; but in such a case, the use of ‘knowledge’ is really only metaphorical, and a sheet of paper where a measurement result is printed out would count as much as ‘knowing’ that result as a conscious observer does.
Moreover, there are well developed interpretations, such as Bohmian mechanics, that reproduce all of QM without any need for observers, knowledge, or consciousness; which demonstrates that believing that such things have no effect is completely consistent with quantum mechanics.
And all that we know is completely consistent with this assumption. Consequently, since throwing it overboard would require some sort of mysterious new ontological category, introducing all the problems that substance dualism suffers from, and not furthering explanation in the least (the most we can know in such a case is that something unknown is doing we don’t know what), it’s at least a reasonable working assumption until it’s conclusively shown false.
Indeed, you need an observer for observation; but that doesn’t imply that said observer features in the underlying physics, and that what is observed depends on any properties of said observer.
The stone changes its state based on physical influences it is subject to—it may become abraded, or may tumble down a hill, or what have you. Just as a human brain changes its state upon being subject to physical influences—photons impinging on retinas, exciting neurons, and so on. There is no reason to believe there is any fundamental difference here.
There are several errors here. Bohm hasn’t shown to be wrong; as I said, Bell was a Bohmian himself. Bell hasn’t shown locality is a myth; only the combination of locality and definite values for all experimentally observable quantities doesn’t hold. Indeed, it is only in theories, such as Bohm’s, which postulate such definite values that one needs to resort to non-local influences; many interpretations of quantum mechanics are perfectly local. And even if you want to keep both locality and value definiteness, you still have many worlds, which evades Bell’s theorem by not having a single definite outcome per measurement, but by all outcomes being equally real.
This is also somewhat confused. Particles don’t need to be ‘in touch’ with one another to ‘know’ when the other is measured; rather, on many common readings, for an entangled pair of particles, one changes state instantaneously as the other is measured, no matter their distance. (This is not the only way to read this situation, though; if you don’t believe in value definiteness, there also is no state change, and all that the situation really says is that there is no joint probability distribution for events that can’t be simultaneously observed, but that would lead us too far.)
No; quantum weirdness, such as it is, is not due to ‘observation influencing the result’, even though it’s regrettably often glossed as such. You can, for example, use so-called interaction-free measurements, where the probe system never interacts with the system you want to measure; this will not change the predictions of quantum mechanics.
What is true is that you can’t hold that measurement results are independent of measurement contexts—i.e. that for a given system, measuring A has the same result no matter whether I simultaneously measure B or C. This is the so-called Kochen-Specker theorem, which can be viewed as a generalization of Bell’s theorem. But again, this has no reference to the observer, but merely to experiments carried out in parallel.
If that’s the extent of your argument, then you can make it just as well in classical mechanics: there, too, you can’t prove anything without the participation of an observer, since there are no experiments without observers. No need to appeal to QM at all!
Unknowable is an absolute. There’s no way around that. Either something can be known, or it can’t. There’s no ‘in-between.’
That’s so general as to be meaningless. Is mathematics ‘in our nature?’ The scientific method? Every construct of the human mind? Practical applications?
This is exactly the reason why physicists use math rather than words or experiences to describe QM.
As soon as you try to bypass the math to make statements about QM or the “real” world, you have lost the argument. That’s why you were dismissed in the first responses. You can construct a philosophy on any grounds you want, to be sure, but you can’t expect others to adhere to it when it contains a giant hole of ignorance.
You seem to be conflating “unknown” and “unknowable”. The former is a simple absence of information, like how I don’t know your hat size. The latter is derived from fundamental theoretical principles. We know that things are unknowable because these principles are well established in both experiment and theory. These are things like Bell’s theorem, the Heisenberg uncertainty principle, and special relativity. These render unknowable, respectively, the inner workings of quantum evolution, the simultaneous knowledge of the position and momentum of a particle, and knowledge of events separated by spacetime that are outside the observer’s past light cone.
And each and every one of those three examples is only a theory. Newtonian physics was well established in both experiment and theory, yet it has been shown that it is only a special case. Much like many other theories that have been modified in the past, so can they. There is no absolute proof of any of the three, nor of ‘unknowability.’ There is no ‘final answer’ in science, only more questions to be answered.
Every time I see “only a” preceding the word “theory”, it tells me that the writer doesn’t understand what a scientific theory is. The entire body of scientific knowledge is comprised of theories. That’s what science is.
This is not about “final answers”, it’s about useful and robust theories that serve as the foundations of further discovery. If any of the theories I mentioned is substantially wrong, we would have to re-invent an unprecedentedly huge amount of basic science. Modern science – the science of the scientific method – advances almost entirely by incremental refinement, occasionally by a major leap, not by crash-and-burn re-invention.