I Consciousness and quantum mechanics

[PeterDonis]

I don't think the basic rules of QM say the moon is there when one isn't looking.

I don't think you can get the prediction that the Moon behaves classically without applying the "collapse" postulate of QM to the Moon even when no one is looking at it.

 

[PeterDonis]

if the photon interacting with any particle at all counts as a "measurement"

That's not what is being said. What is being said is that spreading entanglement due to interactions over a very large number of untrackable degrees of freedom counts as a "measurement".

 

[EPR]

I'm a bit confused by this comment. It seems easy to me because if the photon interacting with any particle at all counts as a "measurement", as it was claimed, then surely the photons or electrons or whatever interacting with, say, the air molecules just before the slit would be enough to destroy it.

Weak interactions(photon and air molucules) do not generally produce collapse. Molecules of metals, plastics, etc. are another matter.

 

[AndreasC]

That's not what is being said. What is being said is that spreading entanglement due to interactions over a very large number of untrackable degrees of freedom counts as a "measurement".

Alright, so doesn't that happen in the case of the interactions before the slit?

 

[AndreasC]

Weak interactions(photon and air molucules) do not generally produce collapse. Molecules of metals, plastics, etc. are another matter.

Why is that? Where is the boundary?

 

[PeterDonis]

Where is the boundary?

The interactions with the air molecules are far too weak to cause decoherence (loss of phase coherence). The interactions with something like a detector screen are not, due to the screen's much higher density.

 

[f95toli]

Right, but that's my issue. How is it possible that we observe such patterns at all if it is this easy for them to get blurred?

It is only "easy" if you use light since photons do not really interact very much with their environment when traveling in vacuum. Generally speaking it is very hard to get a systems to exhibit "quantum behaviour". This is not for any "philosophical" reason but simply because you need to isolate the system extremely well to avoid decoherence.
These days we have a very good understanding for which interactions cause decoherence and we are getting better and better at isolating our systems using ultra high vacuum, low temperatures, ultra-clean materials etc

There are no conceptual problems here; it is just that it is technically very hard.

 

[Stephen Tashi]

We.can observe it directly with some setups.

If we call watching a video "observing directly", we could say that looking at the interference pattern forming in a double slit experiment is observing quantum behavior directly. When things like this happen are we observing Nature doing measurements?

I suppose one could go back and forth on that question depending on whether we think of dots on a screen or cells in the retina reacting to photons as completely specific events (in the classical sense) or whether there are aspects of these events, such as their position, that do not have unique values.

 

[EPR]

I think you can be allowed near the glass and see for yourself water flowing upwards due to quantum superfluidity. This counts as direct observation.
Macroscopic superposition phenomena(BEC's incusive) tend to be less weird than the behaviour of single particles. Perhaps because of averaging.

 

[PeroK]

If we call watching a video "observing directly", we could say that looking at the interference pattern forming in a double slit experiment is observing quantum behavior directly. When things like this happen are we observing Nature doing measurements?

I suppose one could go back and forth on that question depending on whether we think of dots on a screen or cells in the retina reacting to photons as completely specific events (in the classical sense) or whether there are aspects of these events, such as their position, that do not have unique values.

Anything you see involves absorption of photons by your retina. You don't get more quantum than that!

 

[Stephen Tashi]

I think you can be allowed near the glass and see for yourself water flowing upwards due to quantum superfluidity. This counts as direct observation.

I agree that if we have a theory that predicts a measurement then doing the experiment and observing that the measurement agrees with theory is (in a manner of speaking) directly observing the theory.

However, I think you are saying we observe the predictions of QM by doing an experiment and somehow observing something that is not a measurement.

 

[Stephen Tashi]

Anything you see involves absorption of photons by your retina. You don't get more quantum than that!

My question isn't whether such outcomes obey statistics predicted by QM. The question is whether the individual outcomes are particular outcomes from the set of possible outcomes. I gather that the conventional view is that they are not. If they were, we'd have to say which observables take on specific values. Then other non-commuting observables would not have particular values.

Of course their might be salvation through mathematics. Perhaps we can analyze complex physical process by picking a set of observables arbitrarily and modeling a specific occurence of the process as those observables taking on specific values. If the statistical predictions for replications of the process agree no matter which set of observables is chosen, then we are free to imagine the process as sequence of wave function collapses in various ways.

I don't know whether the Monte-Carlo method is used in QM models of phenomena. If it is used, what events define a specific realization of the phenomena? Are the events effectively wave function collapses?

 

[PeroK]

My question isn't whether such outcomes obey statistics predicted by QM. The question is whether the individual outcomes are particular outcomes from the set of possible outcomes.

How can they be anything else? If they are outcomes, they must be from the set of possible outcomes.

 

[Stephen Tashi]

How can they be anything else? If they are outcomes, they must be from the set of possible outcomes.

Yes, if we begin by accepting that a "real" occurrence of a physical process must be a set of particular outcomes from a set of possible outcomes - i.e. a sequence of wave function collapses. But do we accept this type of model?

 

[PeroK]

Yes, if we begin by accepting that a "real" occurrence of a physical process must be a set of particular outcomes from a set of possible outcomes - i.e. a sequence of wave function collapses. But do we accept this type of model?

I'm not sure I understand the question. QM is a model. Whether we accept it is largely down to its predictive capacity. Everything else is inferred.

 

[Stephen Tashi]

I'm not sure I understand the question. QM is a model. Whether we accept it is largely down to its predictive capacity. Everything else is inferred.

To put the question in concrete terms, suppose I want do a Monte Carlo simulation of a double slit experiment. One approach is to compute the probability density for the particle landing at location (x,y) on the screen that is implied by its wave function. Another approach would be to imagine that there are intermediate stages to the process and that the particle is actually somewhere before it hits the screen. For example, it is well known (I think) that simulating the position of the particle with the model that gives it a 0.5 probability of passing through either slit at a non-random time doesn't work. (I don't know whether there is a joint distribution of which-slit and what-time that does.)

Generalizing to complex phenomena like the weather, can we (theoretically) model a particular occurrence of the weather at time T5 by modeling some initial state of a system at time T0 and Monte Carlo-ing the evolution of the system as a sequence of wave function collapses between T0 and T5? Or would we always get different statisics than those implied by computing the evolution of the wave function from T0 to T5?

The way the question is posed, it doesn't specify a particular method for continuing the simulation after a wave function collapse occurs at an intermediate time T2, T0 < T2 < T5. So a proof that there is no possible way to model the evolution of the system as a sequence of wave function collapses would be a strong result.

 

[PeroK]

One approach is to compute the probability density for the particle landing at location (x,y) on the screen that is implied by its wave function.

That's right.

Another approach would be to imagine that there are intermediate stages to the process and that the particle is actually somewhere before it hits the screen.

That won't work. You can't imagine the particle takes a well-defined path and a sequence of wave function collapes.

 

[Stephen Tashi]

You can't imagine the particle takes a well-defined path and a sequence of wave function collapes.

A well defined path would be an infinite sequences of wave function collapses, wouldn't it?

 

[PeroK]

A well defined path would be an infinite sequences of wave function collapses, wouldn't it?

It doesn't really matter whether it's an infinite or finite sequence, it's not the way QM works.

The Feynman path integral formulation works on probability amplitudes, but those are not wave function collapses.

 

[Stephen Tashi]

It doesn't really matter whether it's an infinite or finite sequence, it's not the way QM works.

I agree, but I think you have in mind a particular way of simulating a process as a sequence of intermediate wave collapses - not the question of whether it can be done if we are allowed complete freedom of choice in how to do this and how to model the process after the collapse.

On the one hand, the argument has been made that consciousness is not necessary for causing wave function collapse because natural processes not involving conscious beings cause collapses.

On the other hand you seem to say that a natural process cannot be simulated as a sequence of wave function collapses. If that is the case then how is it that natural processes cause wave function collapses? To model how natural processes cause wave function collapses, must we model the process by stochastically picking times when it will cause a collapse? Or does the consciousness-causes-collapse theory get a second wind by virtue of the fact that a conscious observer must choose when to observe the process?

 

[PeroK]

If that is the case then how is it that natural processes cause wave function collapses?

I guess that, in a nutshell, is the measurement problem.

 

[PeterDonis]

On the one hand, the argument has been made that consciousness is not necessary for causing wave function collapse because natural processes not involving conscious beings cause collapses.

On the other hand you seem to say that a natural process cannot be simulated as a sequence of wave function collapses.

No. Only some natural processes--the ones that do not involve decoherence--cannot be simulated as a sequence of wave function collapses. The orbit of the Moon is a natural process, and can be simulated just fine with a classical model, which is equivalent to a continuous infinity of wave function collapses.

 

[Stephen Tashi]

No. Only some natural processes--the ones that do not involve decoherence--cannot be simulated as a sequence of wave function collapses.

Being mathematically inclined, I'm curious about how such a claim ("cannot be simulated" - in any manner whatsoever) would be stated as a theorem.

The orbit of the Moon is a natural process, and can be simulated just fine with a classical model, which is equivalent to a continuous infinity of wave function collapses.

Is there no way to simulate non-decoherent processes as stochastic realization of a continuous infinity of wave function collapses? For example Brownian motion is such a model. I assume people have tried it and failed, but "no known way" is not the same as "no way".

 

[PeterDonis]

I'm curious about how such a claim ("cannot be simulated" - in any manner whatsoever) would be stated as a theorem.

I'm taking "simulated" to be basically equivalent to "apply some particular mathematical model to make predictions". The mathematical model that makes accurate predictions about the double slit experiment results does not include any wave function collapse within the experiment (although it does at the end when the particle makes a dot on the detector screen). The mathematical model that makes accurate predictions about the motion of the Moon does include continuous wave function collapse (since that is what using classical equations amounts to in quantum terms).

Is there no way to simulate non-decoherent processes as stochastic realization of a continuous infinity of wave function collapses?

I'm not aware of any such model.

For example Brownian motion is such a model.

Brownian motion can't reproduce quantum interference phenomena such as those in the double slit experiment. The phenomena for which Brownian motion makes accurate predictions, such as large molecules in suspension in a fluid, are decoherent processes in quantum terms (since the underlying statistical mechanics that is used is classical).

 

[allisrelative]

Summary:: I am reading a book which quotes from Wigner “Remarks on the Mind-Body Question”. Would appreciate someone’s comment on them.

Reading book, “God? Very Probable”. The author quotes Wigners comments in his book, “Remarks on the Mind- Body Question” 169, 171, 173. “The very study of the external world led to the conclusion that the content of consciousness is an ultimate reality. Given the ultimate priority of consciousness, the quantum physics understanding of reality leads to an intellectual outcome where “solipsism may be logically consistent” with the current state of scientific thinking in physics but it is beyond doubt that “monism in the sense of scientific materialism is not” compatible with contemporary physics.
The author, Robert Nelson, then goes on to quote a similar conclusion from Wheeler in “At Home in the Universe” , 181.
I ask, how do these ideas stand in today’s Theories of quantum mechanics?

Good Quote from Wigner.

To answer your question, it doesn't really stand with today's strict materialist view of QM that wants to reduce the observer to basically nothing and hysterics ensue whenever anyone tries to connect QM and consciousness.

The Founders of QM saw a connection to consciousness.

[Off topic content removed.]

I think the simple solution is to redefine consciousness separate from awareness of consciousness. In the recent experiment around Wigner's Friend, they defined an observer as any mechanical or biological system that can record the quantum state in it's memory.

Using this definition, the universe, a measuring device, animals and humans are all conscious of their environment and the quantum state. Humans have awareness of consciousness which allows us to build civilizations.

The definition of consciousness which includes awareness of consciousness isn't an objective truth. If you just separate the two, all of the confusion goes away.

 

[atyy]

I don't think you can get the prediction that the Moon behaves classically without applying the "collapse" postulate of QM to the Moon even when no one is looking at it.

I agree. So is the difference in our views that I wouldn't mind using "measurement", "observer", "conscious observer" in a related way with regards to the quantum formalism, but you would?

 

[Lord Jestocost]

Summary:: I am reading a book which quotes from Wigner “Remarks on the Mind-Body Question”. Would appreciate someone’s comment on them.

I ask, how do these ideas stand in today’s Theories of quantum mechanics?

For example: "The mental Universe" by Richard Conn Henry, Nature, volume 436, 29 (2005)

Abstract:
The only reality is mind and observations, but observations are not of things. To see the Universe as it really is, we must abandon our tendency to conceptualize observations as things.

 

[PeterDonis]

is the difference in our views that I wouldn't mind using "measurement", "observer", "conscious observer" in a related way with regards to the quantum formalism, but you would?

I'm not sure if we have different views about that. My only concern was to make clear the point that you say you agree with in your latest post. None of the words "measurement", "observer", "conscious observer" can make that clear by themselves.

 

[f95toli]

The Founders of QM saw a connection to consciousness.

It is important to realize that what the founder thought about QM is -quite generally- essentially irrelevant. They did most of their work about a 100 year ago at at time when QM was brand new and nowhere near fully developed; and where most "foundational" experiments had not yet been done. Hence, there was no way they could have an informed opinion about anything.
Some of them also went a bit mad as they got older and came up with all sorts of nonsense. The latter seems to be a almost an occupational hazard for successful scientist (although it could also be that we have a tendency to assume that everything they said was somehow "profound" when we would have just ignored a "normal" person) .

 

[Lord Jestocost]

It is important to realize that what the founder thought about QM is -quite generally- essentially irrelevant.

@f95toli
When making such claims about the founders of QM, it would be helpful when you point to some corresponding texts or articles published by, for example, Werner Heisenberg, Erwin Schrödinger, Max Born, Pascual Jordan, Wolfgang Pauli, Paul Dirac, John von Neumann, Niels Bohr etc. in order to support your claim.