I don't know how many positions there are, but I think I want to cut to the chase, because I think anyone on this list can understand the math I am going to post if they have had arithmetic. I have been buried up to my head in alligators on another list with this stuff but I just posted a post using quantum formalism that explains the problem and incompatibility between consciousness and quantum.

Let's look at von Neumann's seminal book on Quantum, in which he explicitly brings in the subjective observer into quantum.

Originally Posted byJohn Von Newumann, Mathematical Foundations of Quantum Mechanics: New Edition (Princeton: Princeton University Press, 2018), p. 272-273

To prove that it is widely beleived that there are interpretations of quantum which incorporate consciousness, I would present how Zvi Schrieber's view of von Neumann's position. In his thesis, Schrieber entitles a chapter, Mind causes collapse and says

It is interesting that Schrieber understands that there are formulations of quantum involving the immaterial soul, namely the late great John von Neumann's who was a better mathematician/physicist than anyone on this list. Mind and consciousness are synonyms for the same thing.Originally Posted byZvi Schrieber, "The Nine Lives of Schrodinger's Cat, University of London: MS Thesis, Oct 1994, p. 46 [url

Ok, let's get mathematical Sorry everyone else, I think this is necessary but I will try to go slow and explain things. This is taken from Squires' book Conscious Mind in the Physical Universe pages 184-191. It is simplified a bit to the relevant parts of the equations so that it is easier to follow by those with no experience with this notation.

Lets consider the spin of an electron. It is measured in a Stern-Gerlach device and one spin will be deflected upward, and the other spin deflected downward. We will call the upward spin + and the downward spin -. Since I can't use greek letters here or don't know how to, I will use English letters. Wavefunctions are described by | ...> and attributes are put inside where the ... is. I am going to use colors to help those who fear looking at an equation. When you see both colors in an equation, it means that both answers are in superposition.

A particle with an upward spin would be | + > and a particle with a negative spin would be | - >

Before we observe the spin the electron is in the state:

|Psi>=a| + > +b | - >

In words, Psi is the wave function and is it is a mixture of + and - states. a and b are coefficients that for our purposes we don't need to worry about.

One must understand that in quantum, whenever something that is subject to the laws of quantum interacts with an object, it goes into superposition with that object. So, when we add a pointer to the apparatus, which would point up or down , prior to observation of the apparatus, the quantum state would be:

|Psi>=a| +, up > +b | -,down >

The added up and down refer to the direction of the pointer. Before observation, the pointer and the electron are both in mixed states of superposition. In other words, it is in both states at once. This is why one hears that in quantum all possible answers exist at the same time in the wavefunction.

This addition to the chain of objects in superposition can go on forever. Kuttner and Rosenblum describe this von Neumann chain as it is known, because John von Neumann was the first to describe it.

"In his rigourous 1932 treatment, The Mathematical Foundations of Quantum Mechannics, John von Neumann showed that quantum theory makes physics' encounter with consciousness inevitable. He considered a measuring apparatus, a Geiger counter, for example. It is isolated from the rest of the world but makes contact with a quantum system, say, an atom simultaneously in two boxes. This Geiger counter is set to fire if the atom is in the top box and to remain unfired if the atom is in the bottom box. Von Neumann showed that if the Geiger counter is a physical system governed by quantum mechanics, it would enter a superposition state with the atom and be, simultaneously, in a fired and an un fired state. (We saw this situation in the case of Schrodinger's cat.)"

"Should a second isolated measuring apparatus come into contact with the Geiger counter-for example, an electronic device recording whether the Geiger counter has fired-it joins the superposition state and records both situations existing simultaneously.This so-called "von Neumann chain" can continue indefinitely. Von Neumann showed that no physical system obeying the laws of physics (i.e., quantum theory) could collapse a superposition state wavefunction to yield a particular result."

"However, when we look at the Geiger counter, we will always see a particular result, not a superposition. Von Neumann concluded that only a conscious observer doing something that is not presently encompassed by physics can collapse a wavefunction. Though for all practical purposes one can consider the wavefunction collapsed at any macroscopic stage of the von Neumann chain, von Neumann concluded that only a conscious observer can actually make an observation." Bruce Rosenblum and Fred Kuttner, Quantum Enigma, (Oxford: Oxford University Press, 2006), p. 184

It is also interesting that Rosenblum and Kuttner interpret von Neumann the same as Schrieber does.

The von Neumann chain is due to the fact that anything subject to the laws of quantum goes into superposition with what it interacts with. This is a problem. Bryce S. Dewitt talked about quantum putting the apparatus into a schizophrenic state in which it has two different answers at the same time. He says:

This von Neumann chain can continue indefinitely by adding commas and attributes to the chain in between the | and the >. But we won't go there. We will add a conscious observer in at this point and show why he can't be subject to quantum laws.Originally Posted byBryce Dewitt,Quantum Mechanics and Reality, PHYSICS TODAY /SEPTEMBER 1970, p. 30- 31

Back to the math, Let's add me as an observer to the apparatus with the pointer. IF my mind is subject to quantum laws, then I too, must go into superposition with the system. This is just like the pointer in our example or the counter and Geiger counter of Rosenblum and Kuttner's example. In that case, the wave function would be:

|Psi>=a| +, up, Me+ > +b | -,down, Me- >

Where Me+ is the me who sees a positive spin and the Me- is the one who sees a negative spin.

And here is the kicker. Squires says:Originally Posted byEuan Squires, Consciousness Mind in the Physical World, (Adam Hilger, New York, 1990, p. 191

Quantum mechanics does not correctly predict my subjective mental state, which is that I am experiencing only one of the two possible realities.

Squires presented this argument in a paper "Quantum Theory and the Relation between Conscious Mind and the Physical World," Synthese, Vol. 97, No. 1 (Oct., 1993), pp. 109-123. His conclusion there is a bit more interesting:

If you assume that consciousness mind or soul is subject to the laws of quantum, quantum WILL describe any observer in a confused state seeing both possible outcomes. This is the fundamental problem of consciousness in quantum. I only see unmixed states, like:Originally Posted byEuan Squires, "Quantum Theory and the Relation between Conscious Mind and the Physical World," Synthese, Vol. 97, No. 1 (Oct., 1993), p.111-112

|Psi>= | +, up, Me+ >

or |Psi>= b | -,down,Me- >

The thing I don't see is the mixed state

|Psi>=a| +, up, Me+ > +b | -,down,Me- >

Now, Everett proposed the many worlds interpretation in 1957 and he would say that I have split into two different Me's one seeing the up branch and one seeing the down branch. Such a situation is the draw of the many worlds view. But there are other reasons for rejecting the many worlds view.

Point is, this is the problem with consciousness in quantum. If my mind/consciousness/soul is subject to the laws of quantum, it creates a situation where reality (me seeing only one reality) is said to be false by the application of quantum rules.

Again, I affirm that observers external to the physical world is NOT a looney bin idea, but a great problem in the logical structure of quantum. Again, (one of those quotes Pevaquark but a repeat, lol)

"A careful analysis of the logical structure of quantum theory suggests that for quantum theory to make sense it has to posit the existence of observers who lie, at least in part, outside of the description provided by physics." Stephen M. Barr, Modern Physics and Ancient Faith, (Notre Dame: University of Notre Dame Press, 2003), p. 27-28