The need for a "conscious observer"

[StevieTNZ]

A further example of an interpretation is the many minds interpretation.

For illustrative purposes, let's consider the following:
quantum system + apparatus + 1/2 environment (the rest of the universe)

There is, in principle, an observable of the three quantum systems that would indicate, if measured, if all three are in a superposition or not. QM would predict they are.

Add the rest of the universe. The observable above we measured would now become something we can't use to determine if
quantum system + appartus + 1/2 environment + further environment
is in a superposition or not. That would be determined by another observable of all four systems.

EDIT:
Literature:
(1) "The Conceptual Foundations of Quantum Mechanics" by Jeffrey Barrett, OUP, chapter 7.
(2) "Sneaking a Look at God's Cards" by GianCarlo Ghirardi, Princeton, pgs 373 - 376.
(3) "Quantum Mechanics and Experience" by David Albert, Harvard, chapter 8.
(4) Bernard d'Espagnat, https://static.scientificamerican.com/sciam/assets/media/pdf/197911_0158.pdf, who, prior to his death, confirmed to me in email correspondence that his view on the matter had not changed.

 

[PeterDonis]

That claim is separate from my previous, in the same post.

So, again, which one are you trying to defend? You can't say "both" since they are mutually inconsistent. You have to pick one.

 

[PeterDonis]

One could claim the brain and mind are correlated, though consciousness is not caused by physical activity of the brain

Yes, one could, but one would not expect many people to think this was at all plausible.

consciousness is not caused by physical activity of the brain, as it is in a superposition state

This makes no sense to me.

 

[PeterDonis]

There is, in principle, an observable of the three quantum systems that would indicate, if measured, if all three are in a superposition or not. QM would predict they are.

"In a superposition" is vague here; whether or not a particular state is a superposition is basis dependent.

What I think you mean is that, for any joint state of the three subsystems together, there is in principle some observable for which that state is an eigenstate, so measuring that observable does not change the state, it simply tells us which eigenstate of that observable it is. And for most joint states of the three subystems together, the observable of which the state is an eigenstate is not any observable that's familiar to us; for example, if the quantum system is a qubit and the apparatus is suitable for measuring spin, it won't be any observable of the form "qubit in spin-up state, apparatus in state that indicates spin up was measured", etc. It will be some observable that has no straightforward interpretation at all in terms of spin and measurement of spin. So in terms of any basis in which observables like "spin" and "measuring spin" are diagonal, most joint states of the subsystems together will have multiple terms in superposition in such a basis.

 

[StevieTNZ]

It will be some observable that has no straightforward interpretation at all in terms of spin and measurement of spin.

Correct, but the two possible results of the observable will be +1 or -1 to put it in simple terms. An ensemble of the composite systems will always show +1 if the three quantum systems are entangled (not in a definite, classical state, e.g. for one system, spin up, which follows apparatus shows system is spin up and so forth). Had spin up (or down, 1/2 the times) be encountered, one would expect the ensemble to show 1/2 +1 of the observable we're interested in, with the other times -1.

 

[StevieTNZ]

This makes no sense to me.

Think of it as |the brain sees detector 1 go off > + (or - if you prefer) |the brain sees detector 2 go off> (normalised etc.)

 

[StevieTNZ]

Yes, one could, but one would not expect many people to think this was at all plausible.

Of course, and I'm sure you'll agree with, that that on its own does not disregard the suggestion it is actually the case, because something seems unplausible.

It is much like Judge Judy's statement "if it doesn't make sense, it is not true".

 

[PeterDonis]

I'm sure you'll agree with, that that on its own does not disregard the suggestion it is actually the case, because something seems unplausible.

No, I don't agree in this particular case.

 

[PeterDonis]

the two possible results of the observable will be +1 or -1 to put it in simple terms. An ensemble of the composite systems will always show +1 if the three quantum systems are entangled

I don't see how this accomplishes anything like what you are trying to accomplish. Whether or not the systems are entangled depends on whether or not they have interacted, but whether or not they have interacted is already known anyway since it's under the experimenter's control.

If you could give a specific example, in detail, it might help.

 

[PeterDonis]

Think of it as |the brain sees detector 1 go off > + (or - if you prefer) |the brain sees detector 2 go off>

I don't understand what you're trying to accomplish with this.

 

[physika]

One could presume everything is consciousness. See for example Richard Conn Henry's article "The mental universe" - https://www.nature.com/articles/436029a

from https://www.nature.com/articles/436029a

"someone who has learned to accept that nothing exists but observations is far ahead of peers who stumble through physics hoping to find out ‘what things are’."observations of what ??
things that exist out of consciousness ??
thats is just a contradiction.

If:

One could presume everything is consciousness.

-------------

I would say consciousness is outside the realm of physical matter and exists independently of it.

...you have to prove that
.

 

[EPR]

I have a related question:

If you suppose for a moment that this could be an experienced reality, as the Nature paper alludes, this experienced reality must be mirroring a local and realistic reality that probably is not based on the familiar probabilistic quantum foundations. Otherwise, what is the nature of the experienced reality and why is it so imposingly looking as if it's classical in nature? Where does the structure of the classical looking reality stem from?

 

[StevieTNZ]

I don't see how this accomplishes anything like what you are trying to accomplish. Whether or not the systems are entangled depends on whether or not they have interacted, but whether or not they have interacted is already known anyway since it's under the experimenter's control.

If you could give a specific example, in detail, it might help.

See the thought experiments in "Sneaking a Look at God's Cards" and "Quantum Mechanics and Experience".

 

[StevieTNZ]

No, I don't agree in this particular case.

I don't understand what you're trying to accomplish with this.

from https://www.nature.com/articles/436029a

"someone who has learned to accept that nothing exists but observations is far ahead of peers who stumble through physics hoping to find out ‘what things are’."

observations of what ??
things that exist out of consciousness ??
thats is just a contradiction.

If:

-------------

...you have to prove that

I seem to be going around in circles, so I won't bother explaining any further. I can't add to what I've already posted.

 

[allisrelative]

Does unitarity of the evolution of wavefunction get rid of the need for a "conscious observer", and does collapse in contrast demand a "conscious observer"?

For with unitarity there are is no requirement for such an observer, and collapse can't be explained without such an observer.

The "conscious observer" seems to have been cast out of physics, it seems to me. I have no urgent desire for it scientifically, but the question does not appear entirely unscientific to me.

This inspired me to this question:
https://www.youtube.com/channel/UC1aPeLTxBgZmiuzkcUZBTIw (in particular Sean Carroll)

Perhaps best added to this thread: is decoherence a fact or a theory?
And this: should we speak of observed outcomes rather than of just outcomes?

I think the problem is how we define consciousness. We usually include awareness of consciousness in the definition of consciousness. I think the 2 should be separate. So animals, a measuring device, black holes and humans are all observers. An observer just interacts with a quantum system or it's environment and record information about the state in it's memory.

Awareness of consciousness is human's self awareness. With a measuring apparatus, something external has to extract the information stored in it's memory. You can extract that information without the need of an external agent. We can write books about it, build tech around it and ask what it means.

I think you need awareness of consciousness to know what branch of the wave function is being observed. Am I in the branch of the wave function where spin down was measured at 1PM or am I in the branch of the wave function where spin up was measured at 1 PM? Carroll basically tries to reduce the observer to a rock and I think that doesn't make sense in light of recent experiments.

 

[PeterDonis]

See the thought experiments in "Sneaking a Look at God's Cards" and "Quantum Mechanics and Experience".

Neither of those are textbooks or peer-reviewed papers. You referred to the many minds interpretation earlier, and I'm familiar with Albert's discussion of it in "Quantum Mechanics and Experience", but it's still just one interpretation among many, and not all interpretations require or involve consciousness in their explanations. If the only point you are making is that such interpretations exist, consider it made.

 

[PeterDonis]

With a measuring apparatus, something external has to extract the information stored in it's memory. You can extract that information without the need of an external agent.

These two sentences seem to contradict each other.

I think you need awareness of consciousness to know what branch of the wave function is being observed.

No, you don't, you just need macroscopic measuring devices that can register different outcomes.

Carroll basically tries to reduce the observer to a rock

Not at all. A rock is highly insensitive to what is going on around it, so it can't function as a measurement device except for extremely crude measurements ("did a volcanic lava flow pass through?", perhaps). Measuring devices can be much, much, much more sensitive without requiring consciousness.

and I think that doesn't make sense in light of recent experiments.

What specific experiments are you thinking of? Bear in mind that all interpretations of QM make the same predictions for experimental results.

 

[entropy1]

If QM from the view of the MWI is determistic, it might suggest that there is no free will. But could free will be accounted for if creatures that have it could have a say in which outcome, which world, which subjective path will be taken, when a measurement is made?

In case of MWI, this would not hold, because all paths are taken. In case of Copenhagen, a single observer can't be deciding outcomes for all other observers, so it wouldn't hold either.

So if this would exhaust all possibilities of concerning the existence of free will, it looks like there is none of it, and that might mean there is no subjective observer deciding outcomes of measurements?

EDIT: It occurs to me that free will could hide in the realm of measurement not made.

If I'm digressing, I apologize.

 

[physika]

.

"EVERYTHING is consciousness"

"nothing exists but OBSERVATIONS"

then, i ask again:

.- if Everything is consciousness, how can exist things out of consciousness ?

.- how can there be Observations of something outside of consciousness, if Everything is consciousness?

I would say consciousness is outside the realm of physical matter and exists independently of it

...your premises are inconsistent logically..

 

[PeterDonis]

If QM from the view of the MWI is determistic, it might suggest that there is no free will.

Only if you think free will is incompatible with determinism. Not everyone agrees with that; there is a large body of literature on the "compatibilism" viewpoint, which says that free will and deterministic physical laws are compatible.

We have had previous threads in which this was discussed in detail.

 

[StevieTNZ]

Neither of those are textbooks or peer-reviewed papers.

As far as I'm aware, they are textbooks used in Philosophy courses. And as being published by university presses, they are peer-reviewed books.

 

[PeterDonis]

As far as I'm aware, they are textbooks used in Philosophy courses.

This is a physics forum, not a philosophy forum. They're not textbooks on physics.

as being published by university presses, they are peer-reviewed books

Not all university press published books are peer reviewed.

 

[Lord Jestocost]

.- if Everything is consciousness, how can exist things out of consciousness ?

Why must something exist out of consciousness (or mind)? You can never be certain whether all of your putative experience of an - so to speak - outer "reality" is not mere imagining; everything could be purely mental. Maybe, you can call this the approach of idealism.

And it should be clear that science cannot - based upon the scientific method - prove whether there exists an outer "reality made of things". Physics cannot design an operational way to underpin, for example, the viewpoint of either idealism or materialism. No way! As Bertrand Russell remarks in "An Outline of Philosophy": „We cannot find out what the world looks like from a place where there is nobody, because if we go to look there will be somebody there.”

 

[PeterDonis]

You can never be certain whether all of your putative experience of an - so to speak - outer "reality" is not mere imagining; everything could be purely mental. Maybe, you can call this the approach of idealism.

The standard name for what you describe here in philosophy is "solipsism".

it should be clear that science cannot - based upon the scientific method - prove whether there exists an outer "reality made of things".

While this may be true from a philosophical viewpoint, it is irrelevant for the discussion in this thread, and indeed for any discussion in a physics forum. Theories in physics make predictions about what we will observe under particular circumstances; the fact that such theories make correct predictions means that our observations have a structure, which is there regardless of whether you believe there is a "reality made of things" which is the source of our observations or not.

The question under discussion in this thread is whether the theory of quantum mechanics requires a conscious observer to make correct predictions. The answer to that question, while it depends on which interpretation of QM you adopt, does not depend on whether there is a "reality made of things" or not, since QM makes predictions without making any commitment to an answer to that question at all.

 

[Lord Jestocost]

For all practical purposes, you can substitute a measuring device for a conscious observer.

Of course! As Nick Herbert remarks in his book “Quantum Reality: Beyond the New Physics”:

“While searching for a natural place to break his chain, von Neumann proved an important mathematical fact that deepens the mystery of measurement. Von Neumann showed that as far as final results are concerned, you can cut the chain and insert a collapse anywhere you please. This means that the results themselves can offer no clues as to where to locate the division between system and measuring device.” [italics in original, LJ]

Where you place the Heisenberg cut can thus be regarded as a “purely epistemological move without any counterpart in ontology” (as N.P. Landsman characterizes Heisenberg’s and Bohr’s reasoning with respect to the cut in his paper “Between classical and quantum”). So to speak – it’s in your head.

That’s the reason why I am always astonished when people try to “exorcise” consciousness from the thinking about quantum physics by making merely bold declarations without any proof.

 

[StevieTNZ]

I believe the approach "all interpretations give the same predictions" is fundamentally flawed. See the thought experiment in "Sneaking a Look at God's Cards" + page 129 "The Character of Consciousness" by David J Chalmers, OUP

 

[StevieTNZ]

This is a physics forum, not a philosophy forum.

I'm well aware of that, but you said they weren't textbooks in your original post.

 

[PeterDonis]

you said they weren't textbooks in your original post

They aren't physics textbooks. Which is what I said when I responded to you. I thought that response was sufficient clarification of what I meant.

 

[physika]

Why must something exist out of consciousness (or mind)? You can never be certain whether all of your putative experience of an - so to speak - outer "reality" is not mere imagining; everything could be purely mental. Maybe, you can call this the approach of idealism.

And it should be clear that science cannot - based upon the scientific method - prove whether there exists an outer "reality made of things". Physics cannot design an operational way to underpin, for example, the viewpoint of either idealism or materialism. No way! As Bertrand Russell remarks in "An Outline of Philosophy": „We cannot find out what the world looks like from a place where there is nobody, because if we go to look there will be somebody there.”

hey soothe relax

he said that, not me

I would say consciousness is outside the realm of physical matter and exists independently of it (which can give rise to something observing the beginning of the universe). This is basically the essense of the mind-body problem in philosophy.

i just, showed to him a logical inconsistency in his premises.
re-read, that way you will understand..

 

[physika]

The question under discussion in this thread is whether the theory of quantum mechanics requires a conscious observer.

I agree..

 

[AlexCaledin]

Agnosticism seems the only scientific answer! If every observed property is collapse-generated, then how can our science ever know how exactly that collapse works...

(So, the theory has to consider toy systems - real cats not allowed! - with abstract collapse.)

 

[EPR]

[

Agnosticism seems the only scientific answer! If every observed property is collapse-generated, then how can our science ever know how exactly that collapse works...

(So, the theory has to consider toy systems - real cats not allowed! - with abstract collapse.)

I agree. Measurement is everything."Our experiment confirms Bohr’s view that it does not make sense to ascribe the wave or particle behaviour to a massive particle before the measurement takes place."

https://www.nature.com/articles/nphys3343

 

[EPR]

As for the observer question - we're basically animals, like the other animals found in Nature.

I feel there's a strong probability that our perception is quite limited wrt the world out there.
As I've argued before here(and got thread banned), how we 'see' the world is a construct(a mental representation) in the brain. Reality out there probably looks a bit like it appears to us... but surely(looking at our current physical theories) the senses and perception are very basic, primitive, limited and filter out the unnecessary elements for survival.

With better models, we could one day find all the intricacies that were left out of our arcane perception during evolution(be it many worlds, other realities, multiple hidden dimensions, etc.). Einstein said the world out there is weirder than we can imagine. It is.
I do have a feel that our brains play some role in how we perceive the world as a classical reality picking out elements and creating sensations like the icons on your desktop which are there but the inner workings and mechanisms of their manifestation remain hidden and invisible.

The observer is still mostly blind to the wider reality. But we're slowly getting better thanks to scientists who don't believe we've reached the end of the road, yet.

 

[Jehannum]

With the exception of the Wigner interpretation (for which even Wigner himself eventually withdrew support), a conscious observer plays absolutely no role in any of quantum mechanics.
Collapse of the wave function (assuming an interpretation that posits it) is unrelated to consciousness, else the universe could never have evolved a conscious observer.

In a superposition of wave functions of the universe, one of them would contain a conscious observer that could cause collapse. Consciousness is therefore inevitable!

Not that I think any of this is true, I hasten to add. It's just an intriguing idea I heard a long time ago.

 

[physika]

As for the observer question - we're basically animals, like the other animals found in Nature.
I feel there's a strong probability that our perception is quite limited The observer is still mostly blind to the wider reality.

...and who will know how exaggeratedly wide it is

.