Were There Ever Empirical Reasons to Bring Human Consciousness into QM?

[jon4444]

I'm wondering whether physicists in the 1930's ever had experimental reason to interpret, for example, Schrödinger's cat, as a true paradox (because of the role of a human observer). Why didn't they default to Bohr's interpretation, that an interaction with a geiger-counter, or any classically determined system, counts as an "observation."

Bohr's interpretation would seem to be the common-sense way of looking at the situation--interpretations requiring human-consciousness to be involved (which you can still frequently see in the popular press) would seem to reflect some sort of solipsism on the part of the interpreter. (In much the same way that early religious leaders insisted that the universe had to revolve around the planet where they existed.)

 

[Ken G]

But Bohr never said the human consciousness wasn't involved, he merely said that we needn't put the consciousness in separately from how we already do physics. I would say that Bohr, and anyone, can see fairly obviously that the human consciousness is indeed involved in how we do physics, but that is as true classically as in quantum mechanics. Bohr's point was simply that quantum mechanics is subjugated to classical physics, because we need to use our everyday understanding of how classical measurement apparatuses operate before we can even begin to formulate a testable version of quantum mechanics. This makes the paradox go away, because Bohr says that physics is not about what the cat is really doing, it is about what we think the cat is really doing, how we talk about cat behavior in the first place. That's where the human consciousness/intelligence/perceptions comes in (I won't attempt to distinguish those terms since we know so little about them).

 

[lugita15]

Here's a response I gave to a similar question in another thread:

The reason there is still disagreement as to what constitutes measurement is that it makes no experimental difference according to quantum mechanics. The way QM works under the Copenhagen interpretation is that you have to split the world into two parts, the “observer” or measurement device, and the “observed” or the particles you’re measuring.

The measurement device is assumed to behave classically. The particles in the observed system are in a superposition of states described by the wave function which keeps evolving until it interacts with the classical measurement device. The question is where to draw the line. You could consider a photon to be the observed system and an atom to be the measuring device, but you can also consider the photon-and-atom system as in a superposition of states, and take a Geiger counter to be the measurement device. So there is this von-Neumann chain, going from elementary particles to Geiger counters to human beings, and we have to decide where to cut it off.

Von Neumann proved in his famous "Bible" of QM that regardless of where you cut the chain, you would get the same experimental results. But he argued that wherever you cut the chain you have things made out of particles on each side of the cut, so there’s no principled way to place the cut in the middle. So he decided that you should place the cut between the human mind and the human body, because he believed that the mind is non-physical. Hence "consciousness causes collapse" was born. Nowadays, the most popular view is decoherence, where there is no real collapse, it's just that when you have a large number of particles in the environment interacting with the system, the wave function becomes smeared out and looks like it has collapsed. So decoherence gives us a reasonable place to cut the chain, when the number of particles involved reaches a critical number so that interference effect become negligible.

 

[jon4444]

Thanks. This sort of validates the sense I've been getting that the Von Neumann's of the Physics world in fact do exhibit some of the same Solipsism as that of religious fundamentalists. Also, some of this obsessive interpreting regarding QM effects feels pretty sterile (since it has no predictive value).

 

[Ken G]

But there's a funny thing about thinking (obsessing?) about what your theories actually mean-- it can be used to find the problems in them, and indeed, it often has. We're not really in contact with the problems with quantum mechanics, but someday we will be, and it might help a lot to have thought about this stuff.

 

[questionpost]

Why human consciousness? Why not just generalize all consciousness since its all only possible because of matter?

 

[Ken G]

Why human consciousness? Why not just generalize all consciousness since its all only possible because of matter?

Because human consciousness is the only one that is being used to do physics, that we know of. What we know of other consciousnesses is only insofar as they mimic ours-- nothing else.

 

[questionpost]

Because human consciousness is the only one that is being used to do physics, that we know of. What we know of other consciousnesses is only insofar as they mimic ours-- nothing else.

Animals use math and physics all the time, like when they are traveling distance or swimming or calculating where something will be. Even plants use math and physics to grow in the shapes they do. Humans are just the only ones who organize that information in terms of words rather than solely subconsciousactions and feelings.

 

[fellupahill]

Animals use math and physics all the time, like when they are traveling distance or swimming or calculating where something will be. Even plants use math and physics to grow in the shapes they do. Humans are just the only ones who organize that information in terms of words rather than solely subconsciousactions and feelings.

Interesting point.

Kind of brings up the discussion, is their any difference between human consciousness and animal consciousness? Which will ultimately lead to religious talk. And whenever religious people have a better explanation than the science, science hasn't advanced enough yet to decide :)

 

[Neandethal00]

I'm wondering whether physicists in the 1930's ever had experimental reason to interpret, for example, Schrödinger's cat, as a true paradox (because of the role of a human observer). Why didn't they default to Bohr's interpretation, that an interaction with a geiger-counter, or any classically determined system, counts as an "observation."

Bohr's interpretation would seem to be the common-sense way of looking at the situation--interpretations requiring human-consciousness to be involved (which you can still frequently see in the popular press) would seem to reflect some sort of solipsism on the part of the interpreter. (In much the same way that early religious leaders insisted that the universe had to revolve around the planet where they existed.)

I think very recently physicist Penrose is bringing up QM to explain consciousness. He has the nagging problem of explaining how does microscopic quantum world relates to ourselves, the pathways to the humans.

I personally think our consciousness comes from our constituent matters, cells, super molecules, molecules, atoms, and finally elementary particles. That is why QM is emphasized in consciousness. This statement is equivalent to saying 'matters or even elementary particles may have certain type (unlike ours) of consciousness. Our consciousness is a collective 'consciousness' (for the lack of correct word) of particles.

Unfortunately our current Math is not equipped to uncover this mystery. Modern physics heavily rely on Math, and this Math is totally materialistic, void of any 'sensory system' (again, for the lack of better words). Probably quantum Math with its Wave Function come a little closer to a consciousness world but still far away.

 

[bohm2]

I personally think our consciousness comes from our constituent matters, cells, super molecules, molecules, atoms, and finally elementary particles. That is why QM is emphasized in consciousness. This statement is equivalent to saying 'matters or even elementary particles may have certain type (unlike ours) of consciousness. Our consciousness is a collective 'consciousness' (for the lack of correct word) of particles.

I've come across some interesting arguments that do agree very much with this position; that is, in order to explain how the mental/consciousness/subjectivity/qualia emerge from "matter", there must be some fundamental change in our conception of "matter" or "physical", perhaps by a future physics, etc. But as per the "hard" problem, there's no hint of how one can get subjectivity out a complex network of neural connections, etc. (as presently understood). The gap between mind and matter seems immense. They just don't seem to mesh. Consciousness seems to “provide us with a kind of ‘window’ on to our "brain", making possible a transparent grasp of a tiny corner of a materiality that is in general opaque to us" but we haven't the slightest clue of how to mesh it together with what we presently call "matter". An interesting Lockwood passage on this topic:

Do we therefore have no genuine knowledge of the intrinsic character of the physical world? So it might seem. But, according to the line of thought I am now pursuing, we do, in a very limited way, have access to content in the material world as opposed merely to abstract casual structure, since there is a corner of the physical world that we know, not merely by inference from the deliverances of our five sense, but because we are that corner. It is the bit within our skulls, which we know by introspection. In being aware, for example, of the qualia that seemed so troublesome for the materialist, we glimpse the intrinsic nature of what, concretely, realizes the formal structure that a correct physics would attribute to the matter of our brains. In awareness, we are, so to speak, getting an insider's look at our own brain activity.

Neutral Monism
http://plato.stanford.edu/entries/neutral-monism/#7.2

I'm not sure what to make of these arguments but in general I think I agree with Strawson's/Russell's/Eddington's statements that are skeptical about progress in this area happening primarily because mathematics (the language of physics) cannot possibly do that:

This is the “structuralist” point familiar in the 1920s and 1930s (now severely underappreciated outside the philosophy of science, but reviving). It consists in the observation that the propositions of physics are equations, equations that contain numbers, terms that refer without describing, many other mathematical symbols, and nothing else; and that these equations, being what they are, can only tell us about the abstract or mathematically characterizable structure of matter or the physical world without telling us anything else about the nature of the thing that exemplifies the structure. Even in the case of spacetime, as opposed to matter or force—to the doubtful extent that these three things can be separated—it’s unclear whether we have any knowledge of its intrinsic nature beyond its abstract or mathematically representable structure.

Mental Reality
http://mitpress.mit.edu/books/chapters/0262513102pref2.pdf

 

[jon4444]

"Unfortunately our current Math is not equipped to uncover this mystery. Modern physics heavily rely on Math, and this Math is totally materialistic, void of any 'sensory system' (again, for the lack of better words). Probably quantum Math with its Wave Function come a little closer to a consciousness world but still far away."

I like this way of thinking about it, as it seems natural to assume consciousness must rely on some as-yet-discovered physical phenomenon (since the essential aspect of human consciousness--being aware of your awareness--doesn't correlate with any known phenomenon.)

 

[Ken G]

Animals use math and physics all the time, like when they are traveling distance or swimming or calculating where something will be. Even plants use math and physics to grow in the shapes they do. Humans are just the only ones who organize that information in terms of words rather than solely subconsciousactions and feelings.

When you say "animals use math", what you mean is that you recognize what they are doing based on something you do. If you had no idea what math was, you'd have no idea what those words mean. So you are using your own understanding of what math is, that's what I mean by only knowing animals by seeing them as some kind of versions of ourselves. The fact is, we have no idea what animals minds are actually doing when we claim they are doing math, but we suspect that they are doing something vaguely similar-- but only because they are already similar (our brains evolved along similar lines).

 

[Ken G]

I've come across some interesting arguments that do agree very much with this position; that is, in order to explain how the mental/consciousness/subjectivity/qualia emerge from "matter", there must be some fundamental change in our conception of "matter" or "physical", perhaps by a future physics, etc. But as per the "hard" problem, there's no hint of how one can get subjectivity out a complex network of neural connections, etc. (as presently understood). The gap between mind and matter seems immense.

And indeed we probably should never have expected them to mesh, except in the dualistic way that the momentum and position of a particle mesh. The common idea that thought "emerges from" the actions of the material brain is an impossible claim to demonstrate, because every iota of language we have to discuss the material brain comes from thought. So the common claim is that the material world causes thought to occur, and thought describes what the material world is. Eliminating the middle man, this is the claim that material describes, or understands, itself. But I can equally frame it the other way around, and say that thought causes the material world to occur, which then in turn is described by thought. Either way, all we get is a tiger chasing its own tail, so it is obviously impossible to distinguish which is the tiger and which is the tail. Indeed, the entire tiger/tail dichotomy is seen to be bogus-- all we have is a tiger-and-tail relationship that is completely indeterminate about which is which. And we expect the tiger to mesh with its tail? Then you'd have a tiger chasing itself, which is reductionism gone mad-- complete monism is absent of meaning, there needs to be some kind of contrast or tension to have anything nontrivial.

 

[questionpost]

When you say "animals use math", what you mean is that you recognize what they are doing based on something you do. If you had no idea what math was, you'd have no idea what those words mean. So you are using your own understanding of what math is, that's what I mean by only knowing animals by seeing them as some kind of versions of ourselves. The fact is, we have no idea what animals minds are actually doing when we claim they are doing math, but we suspect that they are doing something vaguely similar-- but only because they are already similar (our brains evolved along similar lines).

We actually have a lot of idea on what animals minds do because we can see what chemicals exist in their brain and what they get released in response to as well as see which parts of their brain activate in response to certain things. We've actually found through chemical testing that even fish release endorphin into their blood stream when harmed and even that the same parts of the brain responsible for fear activate at the same time in a person and another animal in the same situation. If anything, animals minds practically are human minds but with different chemical responses and cognitive limitations. You can still see that 1+1=2 without putting the information into words, or even see the slope of a line by noticing how much it goes up by in comparison to how much it goes forward by. There's tons of math that animals and even plants do, just not in terms of words. Things can still exist in specific values without being symbols on a piece of paper.

 

[Ken G]

We actually have a lot of idea on what animals minds do because we can see what chemicals exist in their brain and what they get released in response to as well as see which parts of their brain activate in response to certain things.

Yes but that's just my point. We have no idea what chemicals like that "should" do, we only know what they do in our own brains, because we can correlate two things we understand-- we understand the chemicals, and we understand what our brains are doing (from the internal perspective). Remove either of those pillars and we have nothing that we could call understanding, we have only correlations (when chemical X does Y, animal A does B, but we can say that for a stimulant or a pesticide). None of that can be called "using math" or even "thinking", because we only know what those things are because we do them. Indeed the very definitions of these terms reveal the extent to which we rely on our own minds to give meaning to these terms.

We've actually found through chemical testing that even fish release endorphin into their blood stream when harmed and even that the same parts of the brain responsible for fear activate at the same time in a person and another animal in the same situation.

And that should not be too surprising-- fish brains and human brains evolved along similar lines. I'm not saying fish think differently from us (we should expect both similarities and differences), I'm saying that everything we can say about how fish think relates directly to how we think, because that's how we understand what thought (and math) are. So we are always looking in the mirror to some extent, and that's not a bad thing-- it's just how we understand.

 

[jon4444]

I'm saying that everything we can say about how fish think relates directly to how we think, because that's how we understand what thought (and math) are.

But if we compare our thinking to what we see in animal behavior, I think it's fair to draw general conclusions on basic mental processes common to both. For example, when I watch my cat follow a familiar path to get to a place to hunt, he's clearly using some mental process that has a kinship to my following a "train of thought"--I'm just using language and the self-awareness of "concepts," etc. for the cat's equivalent of markers in the environment. It seems fair to conclude that a core aspect of consciousness, common to both me and my cat (i.e., "mammals") is that of "following a trail."

As far as QM goes, you could extend this to both me and my cat take in stimuli and draw some sort of conclusion based on characteristics of the stimuli (e.g., specific wavelength of light). Thus, cat consciousness, at this level, is roughly equivalent to human consciousness.

 

[Neandethal00]

I've come across some interesting arguments that do agree very much with this position; that is, in order to explain how the mental/consciousness/subjectivity/qualia emerge from "matter", there must be some fundamental change in our conception of "matter" or "physical", perhaps by a future physics, etc.

The quotes you used in your post are more interesting than the materials in the Links.
People have been thinking about the source of our consciousness for centuries. Centuries ago science was not deveoped enough, as a result the topic of consciousness went to the philosophers. This made all answers concerning consciousness very subjective.

Now consciousness is not philosophy anymore, it is Science. It is necessary to take a scientific approach if we intend to discover the source of our consciousness. That brings up my grief about mathematics.

I'm surprised very few scientists spoke out about the limitation of mathematics. Solution of an equation will always contain ONLY the variables used in the equation. You can solve a complicated differential equation, its solution will contain ONLY the variables, coefficients used in the equation. In other words, a mathematical equation (solution) can not 'invent' or 'discover' or 'introduce' a NEW variable (or even a 'constant', which always depends on the values of the variables used) in the solution. One day I took one look at one of Einstein's equations for General Relativity. I immediately knew where the idea of Dark Matter and Dark Energy had come from.

So, it boils down to how truly our mathematical model represent a system. But the system we model is generally physical, with known physical properties. Our mathematics will never be able to discover unknown properties of the system. If consciousness is a 'field', unlike electric, magnetic, or gravitational field, a mathematical model for consciousness will produce a solution for the field in terms of physical properties of humans. Which will not tell us how to detect the 'field'.

I'm hoping QM would evolve. I do not know the current states of QM, I took graduate level QM with dinosaurs and never looked back. If wavefunctions evolve and can model complex phenomena, someday QM may open a path to understanding ourselves. But I also fear there is a huge discontinuity between particle's unknown property we are looking for and our physical sensory system.

 

[questionpost]

Yes but that's just my point. We have no idea what chemicals like that "should" do, we only know what they do in our own brains, because we can correlate two things we understand-- we understand the chemicals, and we understand what our brains are doing (from the internal perspective). Remove either of those pillars and we have nothing that we could call understanding, we have only correlations (when chemical X does Y, animal A does B, but we can say that for a stimulant or a pesticide). None of that can be called "using math" or even "thinking", because we only know what those things are because we do them. Indeed the very definitions of these terms reveal the extent to which we rely on our own minds to give meaning to these terms.
And that should not be too surprising-- fish brains and human brains evolved along similar lines. I'm not saying fish think differently from us (we should expect both similarities and differences), I'm saying that everything we can say about how fish think relates directly to how we think, because that's how we understand what thought (and math) are. So we are always looking in the mirror to some extent, and that's not a bad thing-- it's just how we understand.

I;m losing sight of the point of your argument...
Fish can collapse wave functions just as humans can...

 

[lugita15]

I;m losing sight of the point of your argument...
Fish can collapse wave functions just as humans can...

Look at my post. It's largely a matter of interpretational preference what collapses wave functions and what doesn't. It's perfectly consistent to believe that only human consciousness can collapse the wave function.

 

[Ken G]

But if we compare our thinking to what we see in animal behavior, I think it's fair to draw general conclusions on basic mental processes common to both.

That is exactly what I'm saying. Whenever we talk about "thought" or "using math", what we are doing is trafficking in general conclusions about processes common to our minds and whatever other minds we are including. This means that we are always looking in the mirror when we talk about what thought is.

 

[Ken G]

I;m losing sight of the point of your argument...
Fish can collapse wave functions just as humans can...

The way this emerged was that I was talking about human consciousness, and was asked why limit it to that. I said because that's what we understand. To make the point that other animals can have a consciousness that we understand, on the basis that we understand it when it is similar to our own, is not refuting this core point.

 

[lugita15]

That is exactly what I'm saying. Whenever we talk about "thought" or "using math", what we are doing is trafficking in general conclusions about processes common to our minds and whatever other minds we are including. This means that we are always looking in the mirror when we talk about what thought is.

If you want to take this tack, then it's a short route to not believing that other people are conscious.

 

[Ken G]

Look at my post. It's largely a matter of interpretational preference what collapses wave functions and what doesn't. It's perfectly consistent to believe that only human consciousness can collapse the wave function.

Right, and even if one chooses not to hold this, which as you say is also perfectly consistent, it does not rescue us from the need to account for consciousness somewhere in the program. That's because the consciousness is where we register that collapse has occurred, even if we hold that it actually occurred earlier in the "chain." There just is no chain without the consciousness to anchor it. The reason I mention this is that there are two very separate ways that consciousness can matter to collapse-- one is that it can be connected to the physical cause of collapse, and another (which is the approach I take) is to say that there is no specific "cause of collapse" anywhere in that chain, there is merely the fact that the chain exhibits collapse, and the chain is anchored by consciousness, so consciousness plays a role even if we do not hold that it is a physical cause.

An analogous situation is in Doppler shift of light-- it is neither the motion of the source nor the motion of the receiver that "causes" a Doppler shift, it is the relative motion, and one does not have relative motion until one can anchor that relative motion on some kind of receiver. Without the anchor, there is no cause of the Doppler shift, but one does not say that the motion of the receiver causes the shift.

 

[lugita15]

Right, and even if one chooses not to hold this, which as you say is also perfectly consistent, it does not rescue us from the need to account for consciousness somewhere in the program. That's because the consciousness is where we register that collapse has occurred, even if we hold that it actually occurred earlier in the "chain." There just is no chain without the consciousness to anchor it. The reason I mention this is that there are two very separate ways that consciousness can matter to collapse-- one is that it can be connected to the physical cause of collapse, and another (which is the approach I take) is to say that there is no specific "cause of collapse" anywhere in that chain, there is merely the fact that the chain exhibits collapse, and the chain is anchored by consciousness, so consciousness plays a role even if we do not hold that it is a physical cause.

It is of course a perfectly acceptable interpretation to cut the Von Neumann chain off at consciousness, but it is not required by the theory of quantum mechanics to have a special place for consciousness. You can have a race of robots doing quantum experiments on an island never observed by humans, and there's nothing wrong in thinking that the robots are collapsing the wave function. We don't need to be in the Von Neumann chain at all.

 

[questionpost]

Look at my post. It's largely a matter of interpretational preference what collapses wave functions and what doesn't. It's perfectly consistent to believe that only human consciousness can collapse the wave function.

I's not really consistant at all because if animals didn't and all of their particles always existed in superposition no matter what they would be a tiny bit different. If a simple machine can collapse a wave function, surely animals can. In fact, it's more than illogical to think animals can't considering both humans and the rest of the animal world are made from the same building blocks and chemicals all with similar biological structures. All animals have a brain of which it can be proven that signals are sent to, and if signals are sent from the outside world to it then it is capable of measurement. This is how we know machines are capable of measurement, unless machines don't actually collapse a wave function in which case we have a few major problems with our understanding of QM and every single quantum physicist is non-sense.

The way this emerged was that I was talking about human consciousness, and was asked why limit it to that. I said because that's what we understand. To make the point that other animals can have a consciousness that we understand, on the basis that we understand it when it is similar to our own, is not refuting this core point.

Sure, but that's like saying black holes don't exist because we don't actually "know" what they look like because we've never direcly seen one.

 

[jon4444]

It's perfectly consistent to believe that only human consciousness can collapse the wave function.

Well, this gets back to my original question. Say you had a double slit experiment, that creates a now-familiar interference pattern on inked paper. Are you saying that it's reasonable to interpret results as each time a human looks at the paper, he creates the interference pattern (since the human is bound in the same system as the inked paper and the particles/waves going through the slit)?

If this were true, shouldn't we expect that after a few billion humans looked at the interference pattern, some would see a slightly different pattern of stripes? (I.e., isn't this testable at some level?)

And to bring furry pets back in, what if you trained a dog to bark when he saw a certain pattern of stripes--are we to go so far as to bind the human hearing the bark into the same system?

 

[Ken G]

It is of course a perfectly acceptable interpretation to cut the Von Neumann chain off at consciousness, but it is not required by the theory of quantum mechanics to have a special place for consciousness. You can have a race of robots doing quantum experiments on an island never observed by humans, and there's nothing wrong in thinking that the robots are collapsing the wave function. We don't need to be in the Von Neumann chain at all.

Ah, but we do-- look at your own words: "nothing wrong in thinking that the robots are collapsing..." Who is doing that thinking that there is nothing wrong in? Where is that thinking happening?

 

[Ken G]

Sure, but that's like saying black holes don't exist because we don't actually "know" what they look like because we've never direcly seen one.

I would prefer to say it that the existence, or non-existence, of black holes depends on our participation in the process of doing physics. This is actually perfectly clear-- where does the concept of a "black hole" come from anyway? It makes no difference if we see them or not, what matters is that we conceptualize them. We participate in their existence, whether we choose to hold that they really exist, or we choose to hold that they don't.

 

[Ken G]

And to bring furry pets back in, what if you trained a dog to bark when he saw a certain pattern of stripes--are we to go so far as to bind the human hearing the bark into the same system?

One would simply say that if we regard a dog consciousness as similar to our own, then the dog collapses it, and if we don't, then it collapses when the human hears the dog bark. What experiment will you do that could refute that view?

 

[questionpost]

Well, this gets back to my original question. Say you had a double slit experiment, that creates a now-familiar interference pattern on inked paper. Are you saying that it's reasonable to interpret results as each time a human looks at the paper, he creates the interference pattern (since the human is bound in the same system as the inked paper and the particles/waves going through the slit)?

If this were true, shouldn't we expect that after a few billion humans looked at the interference pattern, some would see a slightly different pattern of stripes? (I.e., isn't this testable at some level?)

And to bring furry pets back in, what if you trained a dog to bark when he saw a certain pattern of stripes--are we to go so far as to bind the human hearing the bark into the same system?

No, consciousness hardly has anything to do with it, it's statistics and math. No matter who's looking at what (or vica versa), particles will have the wave mechanics that they do. Sin(45)=sqrt(2)/2 or 1+1=2 is not based on who is measuring it, it's based on the fundamental logic of what makes a value that specific value. When wave-functions collapse, it's the same principal as making a mathematical statement true, which will be true regardless of who is looking at it. If there is something to measure a particle's position, it's the same equation for any observer (not including Einstein physics, but like if there was multiple species of animals in the same room), so you will yield the same statistical results for each observer.

 

[bhobba]

It had to do with Von Neumann's analysis in the Mathematical Foundations Of QM. He had an argument that seemed to prove the collapse occurred in the mind. Challenging a mathematician of Von Neumann's caliber is no easy task and it took a while for Bell and others to find the 'errors'.

Thanks
Bill

 

[bhobba]

Well, this gets back to my original question. Say you had a double slit experiment, that creates a now-familiar interference pattern on inked paper. Are you saying that it's reasonable to interpret results as each time a human looks at the paper, he creates the interference pattern (since the human is bound in the same system as the inked paper and the particles/waves going through the slit)?

If this were true, shouldn't we expect that after a few billion humans looked at the interference pattern, some would see a slightly different pattern of stripes? (I.e., isn't this testable at some level?)

And to bring furry pets back in, what if you trained a dog to bark when he saw a certain pattern of stripes--are we to go so far as to bind the human hearing the bark into the same system?

The claim of Von Neumann and others is the system and observer (or observers if more than one person views the outcome at the same time) causes the collapse - once it has occurred then its set in concrete and all subsequent observers at later times will observe the same thing if the observation left a record like the live or dead cat in the Schrodinger's cat experiment. To get around the problem you simply need an interpretation that avoids the issue such as the Ensemble Interpretation or Consistent Histories - but all of them suck in their own way - however to me the Ensemble Interpretation sucks the least - but that is a matter of taste.

Thanks
Bill

 

[lugita15]

It had to do with Von Neumann's analysis in the Mathematical Foundations Of QM. He had an argument that seemed to prove the collapse occurred in the mind. Challenging a mathematician of Von Neumann's caliber is no easy task and it took a while for Bell and others to find the 'errors'.

In fact, what Von Neumann proved rigorously in his famous book was not that wave function collapse must occur in the mind, but rather that it makes no experimental difference at what stage you assume the wave function collapses. And then after he proves the theorem, he makes the philosophical argument that if you just believe the wave function collapses at some arbitrary stage, then you just have a set of particles (the apparatus) collapsing the wave function of another set of particles (the system under observation) - and pretty much every possible stage looks the same way. Thus there is no principled way to select one of these stages as being when collapse occurs, so he argues that collapse should occur at a stage that is special. He settles on this special stage being the interaction of the mind and the brain, because bs believed that the brain is physical but the mind isn't.

But they key point is, you have to distinguish between his formal proof, which as far as I kniow is unimpeachable, and the philosophical discussion that follows.

 

[bhobba]

But they key point is, you have to distinguish between his formal proof, which as far as I kniow is unimpeachable, and the philosophical discussion that follows.

That's the whole issue - his mathematics was unimpeachable as you would expect of a mathematician of his caliber - it the interpretation that's the problem. The same with Bell's rebuttal of Von Neumanns proof no hidden variables are possible - the proof was unimpeachable - it was the hidden assumptions that went into it that was the issue. As Bell said once you understood that then you realize the proof, while correct, was silly.

Thanks
Bill

 

[questionpost]

It had to do with Von Neumann's analysis in the Mathematical Foundations Of QM. He had an argument that seemed to prove the collapse occurred in the mind. Challenging a mathematician of Von Neumann's caliber is no easy task and it took a while for Bell and others to find the 'errors'.

Thanks
Bill

Simple machines certainly don't have minds. It doesn't have much to do with a mind or consciousness as much as it does with interaction and math. When things interact, they mathematically change the probability of finding something to a finite point. If I say 1+1=2, you can see that there is no consciousness in that equation, that statement is always true regardless of the observer.
If I have 10 different species of animals in one room who all observe an atom, they will all observer the same statistical probability because there it is the same mechanics of an atom for each individual animal.

 

[Ken G]

It had to do with Von Neumann's analysis in the Mathematical Foundations Of QM. He had an argument that seemed to prove the collapse occurred in the mind. Challenging a mathematician of Von Neumann's caliber is no easy task and it took a while for Bell and others to find the 'errors'.

I see this has been corrected above, von Neumann's "no hidden variables" proof, which is more relevant to Bell, had no errors in it, it merely contained assumptions that Bohm and company did not accept in their interpretation. The point about consciousness is that there is no way to remove it from the situation, so we cannot know what role it plays. One can choose to ignore its importance, and see how far you get, but no one can do an experiment with and without it and see what difference it makes. This makes it very much different from standard physical variables, and quantum mechanics is the place where we begin to see the cracks in the usual way we imagine what physics is. Personally, I think that any new theory which doesn't change what we think physics is can't be a very important new theory.

 

[ThomasT]

I'm wondering whether physicists in the 1930's ever had experimental reason to interpret, for example, Schrödinger's cat, as a true paradox (because of the role of a human observer). Why didn't they default to Bohr's interpretation, that an interaction with a geiger-counter, or any classically determined system, counts as an "observation."

Is there some reason to think that they didn't consider the behavior of detection instruments to be observations?

...interpretations requiring human-consciousness to be involved (which you can still frequently see in the popular press) would seem to reflect some sort of solipsism on the part of the interpreter.

As Ken G noted, of course human consciousness is involved, in the sense that it's our (presumably limited) sensory perceptual capabilities that are the basis for what we call empirical criteria. But I think I understand what you're getting at. And no, I don't think that anybody (well, maybe a few) ever took seriously the idea that human consciousness in any way physically determined the outcomes of experiments. That is, wrt an emission and the chain of amplifications of that emission which might ultimately kill the cat ... no, human consciousness has nothing to do with that. And I doubt that anybody ever thought that it did.

I think what Shroedinger was trying to communicate was his dissatisfaction with the way some people chose to talk about the formalism of the quantum theory. I think of quantum superposition as being an expression of experimental possibilities. That is, there's never any sense in which the cat should be thought of as being both alive and dead. In the same way that we don't think of the possible outcomes of a roll of dice as actually existing simultaneously.

If you open the chamber and the cat is dead, then you can deduce that something caused the vial of poisonous gas to release its contents to the chamber. And, after eliminating all other possibilities, then you can conclude that, indeed, something was emitted from the radioactive material, and that that precipitated the chain of events that eventually killed the cat.

So, what does human consciousness have to do with this? Well, something. A lot actually. But wrt what killed the cat, nothing. As to how the formalism of the quantum theory might be best expressed in ordinary language ... well, I have my preferences, which seem to pretty much coincide with yours. But I guess that ultimately it's a matter of whether one is bent on interpreting the formalism in a way that makes sense in ordinary language, or whether one is bent on creating/preserving unnecessary paradoxes and mysteries.

Quantum experimental phenomena are mysterious enough without clouding the picture with unwarranted ordinary language depictions.

 

[Ken G]

Quantum experimental phenomena are mysterious enough without clouding the picture with unwarranted ordinary language depictions.

And indeed the issue is very much what we should consider warranted, or otherwise. To me it boils down to whether we should subjugate our physics to our everyday experience (which is essentially what we mean by our consciousness, and is the empiricist approach), or should we subjugate our everyday experience to our physics (which is a more rationalistic approach). If you do the former, you approach things from Bohr's perspective, and say that superpositions do not extend to the macro objects of our experience. If you do the latter, you say that unitary evolution is a fact of nature, and must apply to macro objects also (including us, or a reality that includes us as a part), even if we don't perceive it that way. So what seems to be warranted depends critically on this rather fundamentally different way to think about physics, and many different interpretations can be equally valid, they mostly reflect different philosophical priorities.

But I think a basic requirement should be consistency-- too many people use language as if the "laws of physics" were the actual rules that material objects follow, independently of our participation, interpretation, or perception, yet then turn around and say that a cat cannot be in a superposition state-- even though it is those very same laws that say it can (or more correctly, that it can be part of a larger system that is a pure state for which the cat being alive or dead is indeterminate). Personally, I align more with Bohr's empiricist approach, but I also think that if we are going to subjugate our physics to the way we think and perceive our macroscopic environment, then we should certainly recognize the importance that we are giving to our own consciousnesses. If we take the perspective that our observations are the lynchpins of physics, then we must look at how our minds are included in that process, or if we take the perspective that mathematical concepts are the lynchpins, then we must again look at where those concepts reside. Even if we attempt the hard combination, there is no escape from the central role played by our consciousnesses. And for those who say that different people couldn't agree on observations if they depended on consciousnesses, I merely point out that different people are conscious in similar ways, or if they are not, they're absense of agreement is discounted as insanity.

 

[questionpost]

but no one can do an experiment with and without it and see what difference it makes.

Um, a wall? A photo-absorbic wall doesn't have consciousness, but it collapses wave functions to a finite point upon interaction. Simple measuring devices can also do this.
Also, before we even perceive light, the photons hit our retinas where by the wave would be collapsed.

 

[bhobba]

Um, a wall? A photo-absorbic wall doesn't have consciousness, but it collapses wave functions to a finite point upon interaction. Simple measuring devices can also do this.
Also, before we even perceive light, the photons hit our retinas where by the wave would be collapsed.

Its the old does a tree make a sound if it falls but no one is there to hear it issue. We believe, correctly IMHO, simple measuring devices will collapse the wave function, but you can't prove it. Indeed decoherence shows it likely occurs a lot earlier than actually registering on the measuring device. In fact decoherence also explains the wave function collapse pretty much all by itself and interpretations such as Consistent Histories would be my favorite except a few niggling problems remain that require some other stuff to get around eg in Consistent Histories a consistency rule is imposed.

However for anyone that wants to go deeply into it Griffiths Consistent Histories book is an excellent place to start:
http://quantum.phys.cmu.edu/CHS/histories.html

Thanks
Bill

 

[questionpost]

By the laws of physics, a tree makes a sound regardless of if anyone is around if it falls. Plus, the tree is capable of measuring itself in very minute ways, or at least sensing touch.

 

[Ken G]

By the laws of physics, a tree makes a sound regardless of if anyone is around if it falls. Plus, the tree is capable of measuring itself in very minute ways, or at least sensing touch.

If you stipulate that a tree has fallen, then it is natural that it would make a sound. However, the real issue is, how do you stipulate that a tree has fallen in the first place, without a consciousness? Nature has no idea what a "tree" is, or what "falling" is, until we equip it with the trappings of how we think, perceive, and interact with all that we call trees and sound. Whatever is "really going on" might bear quite little resemblance to the models of our language, indeed I for one would be amazed were that not true.

 

[questionpost]

If you stipulate that a tree has fallen, then it is natural that it would make a sound. However, the real issue is, how do you stipulate that a tree has fallen in the first place, without a consciousness? Nature has no idea what a "tree" is, or what "falling" is, until we equip it with the trappings of how we think, perceive, and interact with all that we call trees and sound. Whatever is "really going on" might bear quite little resemblance to the models of our language, indeed I for one would be amazed were that not true.

If the tree makes a sound the sound waves will carry through the and likely cause some kind of reaction. You might not hear it but you could suddenly see a bunch of birds fly away because of what they hear as loud noise or maybe the ground shaking, the insects underground might get startled, or ever hear of that theory that butterflies cause tornadoes?
Not only that, but in a botony class we learned that trees can somehow sense the well-being of other trees, in that trees with rout systems touching others will release sap upon the death of one of the trees in the system, and then there's the tree itself that can probably sense in a way that it's no longer planted in the ground.
Also, what about a wall? There doesn't have to be a single person in the room but it will still collapse a wave function because of the effects of interaction.
What your saying is kind of like that physics doesn't work unless we're around to see it work, which is illogical because then the conditions for life would never have formed.
If you agree that gravity would get weaker by the square of the distance regardless of if anyone is observing it then you should also agree that wave functions can collapse without anyone observing it, because it isn't anything to do with consciousness, it's math.

 

[bohm2]

Even if we attempt the hard combination, there is no escape from the central role played by our consciousnesses. And for those who say that different people couldn't agree on observations if they depended on consciousnesses, I merely point out that different people are conscious in similar ways, or if they are not, they're absense of agreement is discounted as insanity.

I don't think these 2 claims are incompatible:

1. Any theoretical term necessarily fails to capture the world correctly or truthfully (as it is in itself, etc.) since we are "prisoners" of our cognitive structures. So the world as it is, in itself will necessarily escape our characteristics of it. But...
2. Our phenomenal realm and theoretical models aren't purely arbitrary merely "spinning in void". They are causally driven by something external to us; that is, there is a reality that underlies our observations for surely something affects our senses and measurement devices.

There is arguably one exception with respect to point 1. With respect to our own experiences/consciousness, we do have access to it's "intrinsic" nature; to use Russel's term, with respect to our experiences/phenomenal realm, we have "knowledge by acquaintance".