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

[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".