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[http://wordassociation1.net/qcindex.htm Brian Flanagan] and [http://www.amazon.com/exec/obidos/tg/detail/-/0631180311/102-2741775-9726519?v=glance/ Michael Lockwood]. (See references below.) -->
 
[http://wordassociation1.net/qcindex.htm Brian Flanagan] and [http://www.amazon.com/exec/obidos/tg/detail/-/0631180311/102-2741775-9726519?v=glance/ Michael Lockwood]. (See references below.) -->
   
==Introduction==
 
 
A key argument underlying the quantum mind thesis is that [[classical mechanics]] cannot fully explain [[consciousness]]. Proponents have suggested that quantum mechanical phenomena, such as [[quantum entanglement]] and superposition, may play an important part in the brain's function, and could form the basis of an explanation of consciousness.
 
A key argument underlying the quantum mind thesis is that [[classical mechanics]] cannot fully explain [[consciousness]]. Proponents have suggested that quantum mechanical phenomena, such as [[quantum entanglement]] and superposition, may play an important part in the brain's function, and could form the basis of an explanation of consciousness.
   
 
The quantum mind thesis does not as yet have any evidence to confirm its validity, but some role of quantum processes in consciousness has not been completely ruled out. Sufficient understanding of the operation of the brain could prove the proposition false.
 
The quantum mind thesis does not as yet have any evidence to confirm its validity, but some role of quantum processes in consciousness has not been completely ruled out. Sufficient understanding of the operation of the brain could prove the proposition false.
 
===Ongoing Debate===
 
The main argument against the quantum mind proposition is that the structures of the brain are much too large for quantum effects to be important. It is impossible for coherent quantum states to form for very long in the brain and impossible for them to exist at scales on the order of the size of neurons.
 
 
This does not imply that classical mechanics can explain consciousness, but that quantum effects including [[superposition]] and [[entanglement]] are insignificant. [[Quantum chemistry]] is required to understand the actions of [[neurotransmitters]], for example.
 
 
However, this does not preclude the possible existence of mechanisms by which quantum effects could influence the state of larger structures.
 
 
One well-known critic of the quantum mind is [[Max Tegmark]]. Based on his calculations, Tegmark concluded that quantum systems in the brain decohere quickly and cannot control brain function, "This conclusion disagrees with suggestions by Penrose and others that the brain acts as a quantum computer, and that quantum coherence is related to consciousness in a fundamental way"<ref>[http://prola.aps.org/abstract/PRE/v61/i4/p4194_1 Importance of quantum decoherence in brain processes] by [[Max Tegmark]] in [[Physical Review|Phys. Rev. E]] (2000) Volume 61, pages 4194 - 4206.</ref>.
 
 
 
   
 
==Introduction==
 
==Introduction==
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==Various quantum theories of mind==
 
==Various quantum theories of mind==
===Vibrations of the aether===
 
A relation between consciousness and quantum effects has been pondered for nearly a century, and even before that [[Newton]] himself had proposed that vibrations of the [[aether]] might be excited by, and in turn, excite the brain. This speculation forms the conceptual foundation for the modern study of quantum consciousness.
 
   
 
===Modulating quantum jumps===
 
===Modulating quantum jumps===
 
The first modern pioneer of this field was [[biologist]] [[Alfred Lotka]], who in [[1924]], proposed that the mind controls the brain by modulating the quantum jumps that would otherwise lead to a completely random existence. However, the first detailed quantum model of consciousness was by a physicist, [[Evan Walker]]. In [[1970]] he proposed a [[synapse|synaptic]] tunneling model in which [[electron]]s can "tunnel" between adjacent neurons, thereby creating a virtual [[neural network]] overlapping the real one. It is this [[virtual]] nervous system that for Walker produces consciousness and that it can direct the behavior of the real nervous system. In short the real [[nervous system]] operates by means of synaptic messages while the virtual one operates by means of [[quantum tunneling]].
 
The first modern pioneer of this field was [[biologist]] [[Alfred Lotka]], who in [[1924]], proposed that the mind controls the brain by modulating the quantum jumps that would otherwise lead to a completely random existence. However, the first detailed quantum model of consciousness was by a physicist, [[Evan Walker]]. In [[1970]] he proposed a [[synapse|synaptic]] tunneling model in which [[electron]]s can "tunnel" between adjacent neurons, thereby creating a virtual [[neural network]] overlapping the real one. It is this [[virtual]] nervous system that for Walker produces consciousness and that it can direct the behavior of the real nervous system. In short the real [[nervous system]] operates by means of synaptic messages while the virtual one operates by means of [[quantum tunneling]].
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===David Bohm===
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[[David Bohm]] took the view that [[quantum theory]] and [[Theory of relativity|relativity]] contradicted one another, and that this contradiction implied that there existed a more fundamental level in the physical universe<ref>[[#Reference-idBohm2005|Bohm 2005]]</ref>. He claimed that both quantum theory and relativity pointed towards this deeper theory. This more fundamental level was supposed to represent an undivided wholeness and an implicate order, from which arose the explicate order of the universe as we experience it.
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Bohm's implicate order applies both to matter and consciousness, and he proposed that it could explain the relationship between them. Mind and matter are here seen as projections into our explicate order from the underlying reality of the implicate order. Bohm claims that when we look at the matter in space, we can see nothing in these concepts that helps us to understand consciousness.
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In trying to describe the nature of consciousness, Bohm discusses the experience of listening to music. He thinks that the feeling of movement and change that make up our experience of music derives from both the immediate past and the present being held in the brain together, with the notes from the past seen as transformations rather than memories. The notes that were implicate in the immediate past are seen as becoming explicate in the present. Bohm compares this to consciousness emerging from the implicate order.
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Bohm sees the movement, change or flow and also the coherence of experiences such as listening to music as a manifestation of the implicate order. He claims to derive evidence for this from the work of [[Piaget]]<ref>[[#Reference-idPiaget1956|Piaget 1956]]</ref> in studying infants. He claims that these studies show that young children have to learn about time and space, because they are part of the explicate order, but have a 'hard-wired' understanding of movement, because it is part of the implicate order. He compares this 'hard-wiring' to Chomsky's theory that grammar is 'hard-wired' into young human brains. In his writings, Bohm never proposed any specific brain mechanism by which his implicate order could emerge in a way that was relevant to consciousness.
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===Gustav Bernroider===
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Recent papers by physicist Gustav Bernroider, have indicated that he thinks that Bohm's implicate-explicate structure can account for the relationship between neural processes and consciousness<ref>[[#Reference-idBernroider2003|Bernroider 2003]]</ref>. In a paper published in 2005 Bernroider elaborated his proposals for the physical basis of this process<ref name="ReferenceA">[[#Reference-idBernroider2005|Bernroider 2005]]</ref>. The main thrust of his paper was the argument that quantum coherence may be sustained in ion channels for long enough to be relevant for neural processes, and that the channels could be entangled with surrounding lipids and proteins and with other channels in the same membrane. Ion channels regulate the electrical potential across the axon membrane, and thus play a central role in the brain's information processing.
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Bernroider bases his work on recent studies of the potassium (K<sup>+</sup>)ion channel in its closed state and draws particularly on the atomic-level spectroscopy work of the MacKinnon group <ref>[[#Reference-idJiang2003|Jiang 2003]]</ref><ref>[[#Reference-idJiang2003-2|Jiang 2003]]</ref><ref>[[#Reference-idZhou2001|Zhou 2001]]</ref><ref>[[#Reference-idMoraisCabral2001|Morais-Cabral 2001]]</ref><ref>[[#Reference-idDoyle1998|Doyle 1998]]</ref>. The ion channels have a filter region which allows in K<sup>+</sup> ions and bars other ions. These studies show that the filter region has a framework of five sets of four oxygen atoms, which are part of the carboxyl group of amino-acid molecules in the surrounding protein. These are referred to as binding pockets. Two K+ ions are trapped in the selection filter of the closed ion channel. Each of these ions is electrostatically bound to two sets of oxygen atoms or binding pockets, involving eight oxygen atoms in total. Both ions in the channel oscillate between two configurations.
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Bernroider uses this recently revealed structure to speculate about the possibility of quantum coherence in the ion channels. Bernroider and co-author Sisir Roy's calculations suggested to them that the behaviour of the ions in the K channel could only be understood at the quantum level. Taking this as their starting point, they then ask whether the structure of the ion channel can be related to logic states. Further calculations lead them to suggest that the K<sup>+</sup> ions and the oxygen atoms of the binding pockets are two quantum-entangled sub-systems, which they then equate to a quantum computational mapping. The ions that are destined to be expelled from the channel are proposed to encode information about the state of the oxygen atoms. It is further proposed the separate ion channels could be quantum entangled with one another.
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=== David Chalmers ===
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The philosopher David Chalmers has speculated on a number of ways
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in which [[quantum mechanics]] might relate to [[consciousness]].
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<blockquote>
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"One possibility is that instead of postulating novel properties, physics might end up appealing to consciousness itself, in the way that some theorists but not all, hold that quantum mechanics does." <ref>[http://consc.net/papers/nature.pdf Chalmers, D. ''Consciousness and its Place in Nature'']</ref></blockquote>
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<blockquote>
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"The collapse dynamics leaves a door wide open for an [[Mind-body problem#Interactionist dualism|interactionist]] interpretation."
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<ref>[http://consc.net/papers/nature.pdf Chalmers, D. ''Consciousness and its Place in Nature'']</ref></blockquote>
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<blockquote>
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"The most promising version of such an interpretation allows conscious states to be correlated with the total quantum state of a system, with the extra constraint that conscious states (unlike physical states) can never be superposed. In a conscious physical system such as a brain, the physical and phenomenal states of the system will be correlated in a (nonsuperposed) quantum state. Upon observation of a superposed external system, Schrödinger evolution at the moment of observation would cause the observed system to become correlated with the brain, yielding a resulting superposition of brain states and so (by psychophysical correlation) a superposition of conscious states. But such a superposition cannot occur, so one of the potential resulting conscious states is somehow selected (presumably by a nondeterministic dynamic principle at the phenomenal level). The result is that (by psychophysical correlation) a definite brain state and a definite state of the observed object are also selected."
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<ref>[http://consc.net/papers/nature.pdf Chalmers, D. ''Consciousness and its Place in Nature'']</ref></blockquote>
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<blockquote>
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"If physics is supposed to rule out interactionism, then careful attention to the detail of physical theory is required."
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<ref>[http://consc.net/papers/nature.pdf Chalmers, D. ''Consciousness and its Place in Nature'']</ref></blockquote>
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===Roger Penrose===
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In two books, [[The Emperor's New Mind]] and [[Shadows of the Mind]], Penrose argues that
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1. Humans have abilities, particularly mathematical ones, that no algorithmic computer (specifically Turing machine) could have, because computers are limited by [[Gödel's incompleteness theorem]]. In other words, he believes humans are [[hypercomputer]]s. (The argument was originally due to [[John Lucas (philosopher)|John Lucas]].)
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Gödel demonstrated that with any [[recursively enumerable]] set of axioms capable of expressing [[Peano arithmetic]], it was possible to produce a statement that was obviously true, but could not be proved by the axioms. The theorem enjoys general acceptance in the mathematical community<ref>[[#Reference-idNagel1958|Nagel 1958]]</ref>.
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Penrose, however, built a further and highly controversial argument on this theorem. He argued that the theorem showed that the brain had the ability to go beyond what can be demonstrated by mathematical axioms, and therefore there is something within the functioning of the brain that is not based on an algorithm (a system of calculations). A computer is just a system of algorithms, and Penrose claimed that Gödel's theorem demonstrated that brains could perform functions that no computer could perform.
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Penrose is not interested in explaining phenomenal consciousness,
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[[qualia]], generally regarded as the most mysterious feature of consciousness, but instead focuses mainly on the cognitive powers of mathematicians.
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These assertions have been vigorously contested by many critics and notably by the philosophers Churchland and Grush<ref>[[#Reference-idGrush1995]]</ref><ref>[[#Reference-idChurchland1996|Churchland 1996]]</ref>. The theory has been much criticised <ref>[http://philsci-archive.pitt.edu/archive/00003049/ Georgiev, Danko. ''Falsifications of Hameroff-Penrose Orch OR Model of Consciousness and Novel Avenues for Development of Quantum Mind Theory''] </ref>
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<ref>[http://ase.tufts.edu/cogstud/papers/penrose.htm ''Review of Penrose, The Emperor's New Mind'']</ref>
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<ref>[http://web.archive.org/web/20060205192800/http://www.ams.org/bull/pre-1996-data/199507/199507015.pdf Puttnam, H. ''Review of Penrose, The Emperor's New Mind'']</ref>.
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2. This would require some new physics. Penrose postulates that the currently unknown process underlying quantum collapse supplies the non-algorithmic element.
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The random choice of, for instance, the position of a particle, which is involved in the collapse of the wave function was the only physical process that Penrose could find, which was not based on an algorithm. However, randomness was not a promising basis for the quality of mathematical judgement highlighted by his Gödel theorem argument.
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But Penrose went on to propose that when the wave function did not collapse as a result of a measurement or decoherence in the environment, there could be an alternative form of wave function collapse, which he called objective reduction (OR). In this, each quantum superposition has its own space time geometry. When these become separated by more than the Planck length, they are affected by gravity, become unstable and collapse. OR is strikingly different both from the traditional orthodoxy of Niels Bohr's Copenhagen interpretation of quantum theory and from some more modern theories which avoid wave function collapse altogether such as [[Many-worlds interpretation]] or some forms of [[Quantum decoherence]] theory.
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Penrose further proposes that OR is neither random nor governed by an algorithm, but is 'non-computational', selecting information embedded in the fundamental level of space time geometry.
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3. Collapse requires a coherent superposed state to work on. Penrose borrows Stuart Hameroff's proposal about [[microtubule]]s to supply this.
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Initially, Penrose had lacked any detailed proposals for how OR could occur in the brain. Later on cooperation with Stuart Hameroff <ref>[[#Reference-idHameroff1987|Hameroff 1987]]</ref> supplied this side of the theory. Microtubules were central to Hameroff's proposals. These are the core element of the cytoskeleton, which provides a supportive structure and performs various functions in body cells. In additions to these functions, it was now proposed that the microtubules could support macroscopic quantum features known as [[Bose-Einstein condensate]]s. It was also suggested that these condensates could link with other neurons via gap junctions. This is claimed to permit quantum coherence to extend over a large area of the brain. It is suggested that when one of these areas of quantum coherence collapses, there is an instance of consciousness, and the brain has access to a non-computational process embedded in the fundamental level of space time geometry.
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At the same time, it was postulated that conventional synaptic activity influences and is influenced by the activity in the microtubules. This part of the process is referred to as 'orchestration' hence the theory is called Orchestrated Objective Reduction or more commonly [[Orch-OR|Orch OR]].
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Hameroff's proposals like those of Penrose attracted much criticism. However the most cogent attack on Orch OR and quantum mind theories in general was the view that conditions in the brain would lead to any quantum coherence decohering too quickly for it to be relevant to neural processes. This general criticism is discussed in the Science section below.
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===Evan Harris Walker===
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Information theory is concerned with the capacity to contain or carry information. Is there such a thing as a conscious field and a conscious channel capacity?
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Information theory is concerned with the measurement of information in terms of logarithmic probability—how many bits of information does it take to represent a certain type of information such as, let’s say, the letter “T” in print. Since we don’t know all the possible permutations or “combinations” of such a question we use statistical probability in order to be very accurate in our measurements. We add up all the logarithmic contributions of each possible symbol being measured in terms of its chance of occurrence. It is expressed as log₂P. This gives us an informational field potential.
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A physicist, [[Evan Harris Walker]] developed a scientific theory about how the brain might, at quantum levels, process information. In his book, The Physics of Consciousness, he adds log₂P to Schrödinger’s equation. What he demonstrates mathematically is that when information is measured by consciousness and will channel capacities in terms of a closed loop, it forces one real solution only when one probable state happens and all other possible states disappear. He offers/proposes physical evidence that this process is occurring in the brain.
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===Henry Stapp===
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Physically, [[Henry Stapp]]'s approach is aligned with [[objective collapse theory]], in that the deterministic evolution of the [[wave function]], and its indeterministic [[wave function collapse|collapse]] are seen as two real and ontologically distinct phenomena. Collapse events occurring within the brain &mdash; the mind's observation or measurement of the brain &mdash; are particularly important. Since Stapp sees collapse as a mental process and the deterministic evolution of brain states as physical, his approach is philosophically aligned with [[interactionist dualism]]. The process by which collapse selects an actuality from a set of possibilities is seen by Stapp as literally a process of choice, and not merely a random dice-throw. His approach has implications with regard to [[time]]. Since the future depends on decisions in the present, it is not pre-existing, as in the [[block universe]] theory; rather there is an evolving universe in which subjects participate, as
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in [[Whitehead]]'s metaphysics. <ref> [http://sts.lbl.gov/~stapp/Cambridge.pdf stapp, H. ''Quantum Approaches to Consciousness'']</ref>
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Stapp envisages consciousness as exercising top-level control over neural excitation in the brain. Quantum brain events are suggested to occur at the whole brain level, and are seen as being selected from the large-scale excitation of the brain. The neural excitations are viewed as a code, and each conscious experience as a selection from this code. The brain, in this theory, is proposed to be a self-programming computer with a self-sustaining input from memory, which is itself a code derived from previous experience. This process results in a number of probabilities from which consciousness has to select. The conscious act is a selection of a piece of top-level code, which then exercises ongoing control over the flow of neural excitation. This process refers to the top levels of brain activity involved with information gathering, planning and the monitoring of the execution of plans. Conscious events are proposed to be capable of grasping a whole pattern of activity, thus accounting for the unity of consciousness, and providing a solution to the '[[binding problem]]'.
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Stapp's version of the conscious brain is proposed to be a system that is internally determined in a way that cannot be represented outside the system, whereas for the rest of the physical universe an external representation plus a knowledge of the laws of physics allows an accurate prediction of future events.
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Stapp proposes that the proof of his theory requires the identification of the neurons that provide the top-level code and also the process by which memory is turned into additional top-level code.
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===Bose-Einstein condensates===
 
===Bose-Einstein condensates===
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===Conscious matter===
 
===Conscious matter===
 
[[Nick Herbert]], a physicist, has been even more specific on the similarities between Quantum Theory and consciousness. Herbert thinks that consciousness is a pervasive process in nature and that it is as fundamental a component of the universe as [[elementary particles]] and forces. [[James Culbertson]], a pioneer of research on [[robot]]s, has even speculated that consciousness may be a [[relativity|relativistic]] feature of [[space-time]]. In his opinion, too, consciousness permeates all of nature, so that every object has a degree of consciousness. This view is referred to as [[Conscious Matter]].
 
[[Nick Herbert]], a physicist, has been even more specific on the similarities between Quantum Theory and consciousness. Herbert thinks that consciousness is a pervasive process in nature and that it is as fundamental a component of the universe as [[elementary particles]] and forces. [[James Culbertson]], a pioneer of research on [[robot]]s, has even speculated that consciousness may be a [[relativity|relativistic]] feature of [[space-time]]. In his opinion, too, consciousness permeates all of nature, so that every object has a degree of consciousness. This view is referred to as [[Conscious Matter]].
 
===A tripartite model===
 
The American physicist [[Henry Stapp]]'s model of consciousness is tripartite in that each event is driven by three quantum processes operating in concert. The first a [[mechanical]], [[deterministic]] process that predicts the state of the system given its state at a given time. The second is conscious choice. In the formal [[Quantum mechanics|Quantum Theory]] it is implied that something can be known only when Nature is asked a question. This implies,the third that in turn consciousness has a degree of control over Nature because each time something is learned there is a change in the state of the universe, which directly corresponds to a change in the state of the brain. In Q.M. terms; there occurs a reduction of the [[wave function]] compatible with the fact that something has been learned.
 
   
 
===Quantum solitons===
 
===Quantum solitons===
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===The Orch OR model===
 
===The Orch OR model===
The theory espoused by [[Roger Penrose]] and [[Stuart Hameroff]] is [[Quantum-gravitational Consciousness]], and currently it is one of the best developed and the most popular. The Orch OR model presumes that the [[microtubule]] network within neurons acts like a [[quantum computer]]. The [[tubulins]] are in superposition and the collapse of the wave function is driven by the quantum gravity. Penrose and Hameroff believe that conscious information is encoded in space-time geometry at the fundamental [[Planck scale]] and that a [[self-organizing]] Planck-scale process results in awareness.
+
The theory espoused by [[Roger Penrose]] and [[Stuart Hameroff]] is [[Quantum-gravitational Consciousness]], and currently it is one of the best developed and the most popular. The [[Orch OR model]] presumes that the [[microtubule]] network within neurons acts like a [[quantum computer]]. The [[tubulins]] are in superposition and the collapse of the wave function is driven by the quantum gravity. Penrose and Hameroff believe that conscious information is encoded in space-time geometry at the fundamental [[Planck scale]] and that a [[self-organizing]] Planck-scale process results in awareness.
   
 
===M-theory===
 
===M-theory===
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== Consciousness causes collapse ==
 
== Consciousness causes collapse ==
 
[[Consciousness causes collapse]] is the speculative theory that observation by a conscious observer is responsible for the [[wavefunction collapse]] and that the process of [[Quantum indeterminacy|measurement in quantum mechanics]] is consciousness itself.
 
[[Consciousness causes collapse]] is the speculative theory that observation by a conscious observer is responsible for the [[wavefunction collapse]] and that the process of [[Quantum indeterminacy|measurement in quantum mechanics]] is consciousness itself.
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===Ongoing Debate===
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==Ongoing Debate==
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===Science===
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The main argument against the quantum mind proposition is that the structures of the brain are much too large for quantum effects to be important. It is impossible for coherent quantum states to form for very long in the brain and impossible for them to exist at scales on the order of the size of neurons.
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Price, for example, says that quantum effects rarely or never affect human decisions and that classical physics determines the behaviour of [[Neuron]]s.
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{{quote|In quantum terms each neuron is an essentially classical object. Consequently quantum noise in the brain is at such a low level that it probably doesn't often alter, except very rarely, the critical mechanistic behaviour of sufficient neurons to cause a decision to be different than we might otherwise expect. ''(...)''|Michael Clive Price[http://www.hedweb.com/manworld.htm#free-will]}}
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This does not imply that classical mechanics can explain consciousness, but that quantum effects including [[Quantum superposition|superposition]] and [[entanglement]] are insignificant.
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One well-known critic of the quantum mind is [[Max Tegmark]]. Based on his calculations, Tegmark concluded that quantum systems in the brain decohere quickly and cannot control brain function, "This conclusion disagrees with suggestions by Penrose and others that the brain acts as a quantum computer, and that quantum coherence is related to consciousness in a fundamental way"<ref>[http://prola.aps.org/abstract/PRE/v61/i4/p4194_1 Importance of quantum decoherence in brain processes] by [[Max Tegmark]] in [[Physical Review|Phys. Rev. E]] (2000) Volume 61, pages 4194 - 4206.</ref>
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Proponents of quantum consciousness theories have sought to defend them against Tegmark's criticism. In respect of QBD, Vitiello has argued that Tegmark's work applies to theories based on quantum mechanics but not to those such as QBD that are based on quantum field theory. In respect of Penrose and Hameroff's Orch OR theory, Hameroff along with Hagan and Tuszynski replied to Tegmark<ref>[[#Reference-idHagan2002|Hagan 2002]]</ref>. They claimed that Tegmark based his calculations on a model that was different from Orch OR. It is argued that in the Orch OR model the microtubules are shielded from decoherence by ordered water. Energy pumping as a result of thermal disequilibrium, Debye layer screening and quantum error correction, deriving from the geometry of the [[microtubule]] lattice are also proposed as possible sources of shielding. Similarly, in his extension of Bohm's ideas, Bernroider has claimed that the binding pockets in the ion selection filters could protect against decoherence<ref name="ReferenceA"/>. So far, however, there has been no experimental confirmation of the ability of the features mentioned above to protect against decoherence.
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===Philosophy===
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Another line of criticism is that no physical theory is well suited to explaining [[consciousness]], particularly in its most problematical form, phenomenal [[consciousness]] or ''[[qualia]]'', known as the [[hard problem of consciousness]].<ref>Saul-Paul Sirag"[http://www.williamjames.com/Theory/Consciousness.pdf Consciousness:A Hyperspace View]"</ref> It is not so much that colours and tastes and feelings—[[qualia]] or [[secondary qualities]]—have been deliberately banished, but more that they cannot be captured in any mathematical description, which means they cannot be explicitly represented in [[physics]], since all physical theory is expressed in [[mathematical]] language (as explained in [[Eugene Wigner|Eugene Wigner's]] famous paper [[The Unreasonable Effectiveness of Mathematics in the Natural Sciences]]). If no physical theory can express qualia, no physical theory can fully explain consciousness. Replacing the mathematical apparatus of classical physics with the mathematical apparatus of [[quantum mechanics]] is therefore of no help in understanding consciousness, and indeed there is no known example of a quantum equation which encapsulates a taste or colour.
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As David Chalmers puts it:
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<blockquote>
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Nevertheless, quantum theories of consciousness suffer from the same difficulties as neural or computational theories. Quantum phenomena have some remarkable functional properties, such as nondeterminism and nonlocality. It is natural to speculate that these properties may play some role in the explanation of cognitive functions, such as random choice and the integration of information, and this hypothesis cannot be ruled out a priori. But when it comes to the explanation of experience, quantum processes are in the same boat as any other. The question of why these processes should give rise to experience is entirely unanswered.
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<ref name="consc.net"/>
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</blockquote>
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Other philosophers, such as [[Patricia Churchland|Patricia]] and [[Paul Churchland]] and [[Daniel Dennett]]<ref>[http://ase.tufts.edu/cogstud/papers/chalmers.htm Dennet, D. ''Facing Backwards on the Problem of Consciousness'']</ref> reject the idea that there is anything puzzling about consciousness in the first place.
   
 
==See also==
 
==See also==
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*[http://en.wikibooks.org/wiki/Consciousness_studies:_Table_of_theories Consciousness studies: Table of theories]
 
*[http://en.wikibooks.org/wiki/Consciousness_studies:_Table_of_theories Consciousness studies: Table of theories]
   
==References==
+
==Notes==
  +
{{reflist}}
{{Wikibookspar|Consciousness studies| }}
 
   
  +
==References==
 
*Atiyah, MF. Geometry of Yang-Mills Fields. Pisa, Italy: Accademia Nazionale Dei Lincei Scuola Normale Superiore, 1979.
 
*Atiyah, MF. Geometry of Yang-Mills Fields. Pisa, Italy: Accademia Nazionale Dei Lincei Scuola Normale Superiore, 1979.
 
*Bennett, Charles H., Shor, Peter W., Smolin, John A. and Thapliyal, Ashish V. "Entanglement-Assisted Classical Capacity of Noisy Quantum Channels," Phys. Rev. Lett. 83, 3081–3084 (1999). (http://prola.aps.org/abstract/PRL/v83/i15/p3081_1)
 
*Bennett, Charles H., Shor, Peter W., Smolin, John A. and Thapliyal, Ashish V. "Entanglement-Assisted Classical Capacity of Noisy Quantum Channels," Phys. Rev. Lett. 83, 3081–3084 (1999). (http://prola.aps.org/abstract/PRL/v83/i15/p3081_1)

Latest revision as of 19:40, 3 September 2014

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The quantum mind or quantum consciousness is a protoscientific hypothesis that posits a connection between consciousness, neurobiology and quantum mechanics. There are many blank areas in understanding the brain dynamics and especially how it gives rise to consciousness. The hypothesis claims that quantum mechanics is capable of explaining conscious experience.

The quantum mind theory is founded on the premise that quantum theory is necessary to fully understand the mind and brain, particularly concerning an explanation of consciousness. This is considered a minority opinion in science, although it does have the support of the well-known mathematical physicist Sir Roger Penrose. Other proponents include Stuart Hameroff, Karl Pribram and Henry Stapp. Brian Flanagan and Michael Lockwood. (See references below.) -->

A key argument underlying the quantum mind thesis is that classical mechanics cannot fully explain consciousness. Proponents have suggested that quantum mechanical phenomena, such as quantum entanglement and superposition, may play an important part in the brain's function, and could form the basis of an explanation of consciousness.

The quantum mind thesis does not as yet have any evidence to confirm its validity, but some role of quantum processes in consciousness has not been completely ruled out. Sufficient understanding of the operation of the brain could prove the proposition false.

Introduction

The nature of consciousness and its place in the universe remain unknown. Classical models view consciousness as computation among the brain's neurons but as yet has failed to describe an exact mechanism. Quantum processes in the brain have been invoked as explanations for consciousness and its enigmatic features. Some theories have been subjected to experimental tests and evidence indicating that quantum non-locality is occurring in conscious and subconscious brain functions has been claimed, however these results have not gained wide acceptance.

Supporters argue that the brain can no longer be seen as simply a vast piece of organic clockwork, but as a subtle device amplifying quantum events and that quantum computation would surely be advantageous from an evolutionary perspective, and biology has had 4 billion years to solve the decoherence problem and evolve quantum mechanisms.

The main argumentative line can be summed up as follows: Human thought, based on the Gödel result, is sound, yet non-algorithmic, and the human thinker is aware of or conscious of the contents of these thoughts. The only recognized instances of non-algorithmic processes in the universe, based on accepted physical theories are purely random or the reduction of the quantum mechanical state vector. Randomness is not promising as the source of the non-algorithmicity needed to account for consciousness, therefore certain quantum mechanical phenomena must be responsible.

Critics deride this comparison as a mere "minimization of mysteries," ( A term coined by David Chalmers, the idea that since quantum and consciousness are both mysteries, they must be related.) and point out that the brain is too warm for quantum computation, which in the technological realm requires extreme cold to avoid "decoherence" (i.e. the loss of seemingly delicate quantum states by interaction with the environment.)


Various quantum theories of mind

Modulating quantum jumps

The first modern pioneer of this field was biologist Alfred Lotka, who in 1924, proposed that the mind controls the brain by modulating the quantum jumps that would otherwise lead to a completely random existence. However, the first detailed quantum model of consciousness was by a physicist, Evan Walker. In 1970 he proposed a synaptic tunneling model in which electrons can "tunnel" between adjacent neurons, thereby creating a virtual neural network overlapping the real one. It is this virtual nervous system that for Walker produces consciousness and that it can direct the behavior of the real nervous system. In short the real nervous system operates by means of synaptic messages while the virtual one operates by means of quantum tunneling.

David Bohm

David Bohm took the view that quantum theory and relativity contradicted one another, and that this contradiction implied that there existed a more fundamental level in the physical universe[1]. He claimed that both quantum theory and relativity pointed towards this deeper theory. This more fundamental level was supposed to represent an undivided wholeness and an implicate order, from which arose the explicate order of the universe as we experience it.

Bohm's implicate order applies both to matter and consciousness, and he proposed that it could explain the relationship between them. Mind and matter are here seen as projections into our explicate order from the underlying reality of the implicate order. Bohm claims that when we look at the matter in space, we can see nothing in these concepts that helps us to understand consciousness.

In trying to describe the nature of consciousness, Bohm discusses the experience of listening to music. He thinks that the feeling of movement and change that make up our experience of music derives from both the immediate past and the present being held in the brain together, with the notes from the past seen as transformations rather than memories. The notes that were implicate in the immediate past are seen as becoming explicate in the present. Bohm compares this to consciousness emerging from the implicate order.

Bohm sees the movement, change or flow and also the coherence of experiences such as listening to music as a manifestation of the implicate order. He claims to derive evidence for this from the work of Piaget[2] in studying infants. He claims that these studies show that young children have to learn about time and space, because they are part of the explicate order, but have a 'hard-wired' understanding of movement, because it is part of the implicate order. He compares this 'hard-wiring' to Chomsky's theory that grammar is 'hard-wired' into young human brains. In his writings, Bohm never proposed any specific brain mechanism by which his implicate order could emerge in a way that was relevant to consciousness.

Gustav Bernroider

Recent papers by physicist Gustav Bernroider, have indicated that he thinks that Bohm's implicate-explicate structure can account for the relationship between neural processes and consciousness[3]. In a paper published in 2005 Bernroider elaborated his proposals for the physical basis of this process[4]. The main thrust of his paper was the argument that quantum coherence may be sustained in ion channels for long enough to be relevant for neural processes, and that the channels could be entangled with surrounding lipids and proteins and with other channels in the same membrane. Ion channels regulate the electrical potential across the axon membrane, and thus play a central role in the brain's information processing.

Bernroider bases his work on recent studies of the potassium (K+)ion channel in its closed state and draws particularly on the atomic-level spectroscopy work of the MacKinnon group [5][6][7][8][9]. The ion channels have a filter region which allows in K+ ions and bars other ions. These studies show that the filter region has a framework of five sets of four oxygen atoms, which are part of the carboxyl group of amino-acid molecules in the surrounding protein. These are referred to as binding pockets. Two K+ ions are trapped in the selection filter of the closed ion channel. Each of these ions is electrostatically bound to two sets of oxygen atoms or binding pockets, involving eight oxygen atoms in total. Both ions in the channel oscillate between two configurations.

Bernroider uses this recently revealed structure to speculate about the possibility of quantum coherence in the ion channels. Bernroider and co-author Sisir Roy's calculations suggested to them that the behaviour of the ions in the K channel could only be understood at the quantum level. Taking this as their starting point, they then ask whether the structure of the ion channel can be related to logic states. Further calculations lead them to suggest that the K+ ions and the oxygen atoms of the binding pockets are two quantum-entangled sub-systems, which they then equate to a quantum computational mapping. The ions that are destined to be expelled from the channel are proposed to encode information about the state of the oxygen atoms. It is further proposed the separate ion channels could be quantum entangled with one another.

David Chalmers

The philosopher David Chalmers has speculated on a number of ways in which quantum mechanics might relate to consciousness.

"One possibility is that instead of postulating novel properties, physics might end up appealing to consciousness itself, in the way that some theorists but not all, hold that quantum mechanics does." [10]

"The collapse dynamics leaves a door wide open for an interactionist interpretation."

[11]

"The most promising version of such an interpretation allows conscious states to be correlated with the total quantum state of a system, with the extra constraint that conscious states (unlike physical states) can never be superposed. In a conscious physical system such as a brain, the physical and phenomenal states of the system will be correlated in a (nonsuperposed) quantum state. Upon observation of a superposed external system, Schrödinger evolution at the moment of observation would cause the observed system to become correlated with the brain, yielding a resulting superposition of brain states and so (by psychophysical correlation) a superposition of conscious states. But such a superposition cannot occur, so one of the potential resulting conscious states is somehow selected (presumably by a nondeterministic dynamic principle at the phenomenal level). The result is that (by psychophysical correlation) a definite brain state and a definite state of the observed object are also selected."

[12]

"If physics is supposed to rule out interactionism, then careful attention to the detail of physical theory is required."

[13]

Roger Penrose

In two books, The Emperor's New Mind and Shadows of the Mind, Penrose argues that

1. Humans have abilities, particularly mathematical ones, that no algorithmic computer (specifically Turing machine) could have, because computers are limited by Gödel's incompleteness theorem. In other words, he believes humans are hypercomputers. (The argument was originally due to John Lucas.)

Gödel demonstrated that with any recursively enumerable set of axioms capable of expressing Peano arithmetic, it was possible to produce a statement that was obviously true, but could not be proved by the axioms. The theorem enjoys general acceptance in the mathematical community[14].

Penrose, however, built a further and highly controversial argument on this theorem. He argued that the theorem showed that the brain had the ability to go beyond what can be demonstrated by mathematical axioms, and therefore there is something within the functioning of the brain that is not based on an algorithm (a system of calculations). A computer is just a system of algorithms, and Penrose claimed that Gödel's theorem demonstrated that brains could perform functions that no computer could perform.

Penrose is not interested in explaining phenomenal consciousness, qualia, generally regarded as the most mysterious feature of consciousness, but instead focuses mainly on the cognitive powers of mathematicians.

These assertions have been vigorously contested by many critics and notably by the philosophers Churchland and Grush[15][16]. The theory has been much criticised [17] [18] [19].

2. This would require some new physics. Penrose postulates that the currently unknown process underlying quantum collapse supplies the non-algorithmic element.

The random choice of, for instance, the position of a particle, which is involved in the collapse of the wave function was the only physical process that Penrose could find, which was not based on an algorithm. However, randomness was not a promising basis for the quality of mathematical judgement highlighted by his Gödel theorem argument.

But Penrose went on to propose that when the wave function did not collapse as a result of a measurement or decoherence in the environment, there could be an alternative form of wave function collapse, which he called objective reduction (OR). In this, each quantum superposition has its own space time geometry. When these become separated by more than the Planck length, they are affected by gravity, become unstable and collapse. OR is strikingly different both from the traditional orthodoxy of Niels Bohr's Copenhagen interpretation of quantum theory and from some more modern theories which avoid wave function collapse altogether such as Many-worlds interpretation or some forms of Quantum decoherence theory.

Penrose further proposes that OR is neither random nor governed by an algorithm, but is 'non-computational', selecting information embedded in the fundamental level of space time geometry.

3. Collapse requires a coherent superposed state to work on. Penrose borrows Stuart Hameroff's proposal about microtubules to supply this.

Initially, Penrose had lacked any detailed proposals for how OR could occur in the brain. Later on cooperation with Stuart Hameroff [20] supplied this side of the theory. Microtubules were central to Hameroff's proposals. These are the core element of the cytoskeleton, which provides a supportive structure and performs various functions in body cells. In additions to these functions, it was now proposed that the microtubules could support macroscopic quantum features known as Bose-Einstein condensates. It was also suggested that these condensates could link with other neurons via gap junctions. This is claimed to permit quantum coherence to extend over a large area of the brain. It is suggested that when one of these areas of quantum coherence collapses, there is an instance of consciousness, and the brain has access to a non-computational process embedded in the fundamental level of space time geometry.

At the same time, it was postulated that conventional synaptic activity influences and is influenced by the activity in the microtubules. This part of the process is referred to as 'orchestration' hence the theory is called Orchestrated Objective Reduction or more commonly Orch OR.

Hameroff's proposals like those of Penrose attracted much criticism. However the most cogent attack on Orch OR and quantum mind theories in general was the view that conditions in the brain would lead to any quantum coherence decohering too quickly for it to be relevant to neural processes. This general criticism is discussed in the Science section below.

Evan Harris Walker

Information theory is concerned with the capacity to contain or carry information. Is there such a thing as a conscious field and a conscious channel capacity?

Information theory is concerned with the measurement of information in terms of logarithmic probability—how many bits of information does it take to represent a certain type of information such as, let’s say, the letter “T” in print. Since we don’t know all the possible permutations or “combinations” of such a question we use statistical probability in order to be very accurate in our measurements. We add up all the logarithmic contributions of each possible symbol being measured in terms of its chance of occurrence. It is expressed as log₂P. This gives us an informational field potential.

A physicist, Evan Harris Walker developed a scientific theory about how the brain might, at quantum levels, process information. In his book, The Physics of Consciousness, he adds log₂P to Schrödinger’s equation. What he demonstrates mathematically is that when information is measured by consciousness and will channel capacities in terms of a closed loop, it forces one real solution only when one probable state happens and all other possible states disappear. He offers/proposes physical evidence that this process is occurring in the brain.

Henry Stapp

Physically, Henry Stapp's approach is aligned with objective collapse theory, in that the deterministic evolution of the wave function, and its indeterministic collapse are seen as two real and ontologically distinct phenomena. Collapse events occurring within the brain — the mind's observation or measurement of the brain — are particularly important. Since Stapp sees collapse as a mental process and the deterministic evolution of brain states as physical, his approach is philosophically aligned with interactionist dualism. The process by which collapse selects an actuality from a set of possibilities is seen by Stapp as literally a process of choice, and not merely a random dice-throw. His approach has implications with regard to time. Since the future depends on decisions in the present, it is not pre-existing, as in the block universe theory; rather there is an evolving universe in which subjects participate, as in Whitehead's metaphysics. [21]

Stapp envisages consciousness as exercising top-level control over neural excitation in the brain. Quantum brain events are suggested to occur at the whole brain level, and are seen as being selected from the large-scale excitation of the brain. The neural excitations are viewed as a code, and each conscious experience as a selection from this code. The brain, in this theory, is proposed to be a self-programming computer with a self-sustaining input from memory, which is itself a code derived from previous experience. This process results in a number of probabilities from which consciousness has to select. The conscious act is a selection of a piece of top-level code, which then exercises ongoing control over the flow of neural excitation. This process refers to the top levels of brain activity involved with information gathering, planning and the monitoring of the execution of plans. Conscious events are proposed to be capable of grasping a whole pattern of activity, thus accounting for the unity of consciousness, and providing a solution to the 'binding problem'.

Stapp's version of the conscious brain is proposed to be a system that is internally determined in a way that cannot be represented outside the system, whereas for the rest of the physical universe an external representation plus a knowledge of the laws of physics allows an accurate prediction of future events.

Stapp proposes that the proof of his theory requires the identification of the neurons that provide the top-level code and also the process by which memory is turned into additional top-level code.


Bose-Einstein condensates

In 1989 the British psychiatrist Ian Marshall examined similarities between the holistic properties of Bose-Einstein condensates and those of consciousness. In 1968 the British physicist Herbert Fröhlich had suggested that condensation similar to Bose-Einstein can be achieved in Nature by biological organisms which are in a non-equilibrium state. In Marshall's hypothesis, the brain contains a Frölich-style condensate, and, whenever the condensate is excited by an electrical field, conscious experience occurs. Marshall theory contends that the brain would maintain its dynamical coherence due precisely to the properties of such a condensate.

Synaptic quantum uncertainty

John Carew Eccles speculated in 1986 that the synapses in the cortex may respond in a probabilistic manner to neural excitation; a probability that, given the small dimensions of synapses, could be governed by quantum uncertainty.

Consciousness as the observer

The philosopher Michael Lockwood noted that special relativity implies that mental states must be physical states. He argued that sensations must be intrinsic attributes of physical brain states. Thus in quantum terms each sensation corresponds to an observable event in the brain; this makes the observer, in quantum mechanics, conscious of the physical world.

Conscious matter

Nick Herbert, a physicist, has been even more specific on the similarities between Quantum Theory and consciousness. Herbert thinks that consciousness is a pervasive process in nature and that it is as fundamental a component of the universe as elementary particles and forces. James Culbertson, a pioneer of research on robots, has even speculated that consciousness may be a relativistic feature of space-time. In his opinion, too, consciousness permeates all of nature, so that every object has a degree of consciousness. This view is referred to as Conscious Matter.

Quantum solitons

Stuart Hameroff, A. Nip, M. Porter and J. A. Tuszynski have claimed that the neuronal cytoskeletons are primary residence for consciousness and that the specific protein organization and functions help the quantum mind control overall brain dynamics according to the received electromagnetic input. He proposes that when the microtubules strongly interact with the local electromagnetic field solitons could be generated and could propagate along intraprotein conduction aromatic acid pathways. Thus quantum soliton creation could be induced in microtubules via interaction with the local electromagnetic field. See Quantum brain dynamics

Thought as a hologram

Many properties of the brain are the same properties that are commonly associated with holograms: memory is distributed in the brain and memories do not disappear all of a sudden, but slowly fade away. To psychologist Karl Pribram, a sensory perception is transformed in a "brain wave", a pattern of electromagnetical activation that propagates through the brain just like the wavefront in a liquid. The various waves that travel through the brain can interfere. The interference of existing waves (a memory), and a fresh perceptual wave (sensory input) generates a structure that resembles a hologram that is experienced as thought. Pribram refers to this as Holonomic brain theory

A string theory model

A string theory model was developed by D. Nanopoulos in 1996 that was further refined into a QED-Cavity model by N. Mavromatos in 2000 suggesting dissipationless energy transfer and biological quantum teleportation.

Quantum neurophysics

The Heisenberg and Von Neumann tradition has always viewed the brain as a quantum measuring device but others, claim that brain substrates can hold second-order quantum fields, which cannot be treated as mere measuring devices. This is the position of Kunio Yasue, a Japanese physicist who has developed quantum neurophysics. Yasue presents the brain as a macroscopic quantum system wherein the classical world can originate from quantum processes. Not a connectionist, the fact that neurons are organized inside the brain is not relevant to Yasue. See Quantum brain dynamics for references.

Space-time theories of consciousness

Alex Green has developed an empirical theory of phenomenal consciousness that proposes that conscious experience can be described as a five-dimensional manifold. As in Broad's hypothesis, space-time can contain vectors of zero length between two points in space and time because of an imaginary time coordinate. A 3D volume of brain activity over a short period of time would have the time extended geometric form of a conscious observation in 5D. Green considers imaginary time to be incompatible with the modern physical description of the world, and proposes that the imaginary time coordinate is a property of the observer and unobserved things (things governed by quantum mechanics), whereas the real time of general relativity is a property of observed things.

Quantum spin-mediated consciousness

The spin-mediated consciousness theory, initially proposed by biophysicist Huping Hu with his collaborator Maoxin Wu is a theory that says quantum spin is the seat of consciousness and the linchpin between mind and the brain, that is, spin is the mind-pixel. According to this theory, Quantum consciousness is intrinsically connected to the spin process and emerges from the self-referential collapses of spin states and the unity of mind is achieved by entanglement of these mind-pixels.

The Orch OR model

The theory espoused by Roger Penrose and Stuart Hameroff is Quantum-gravitational Consciousness, and currently it is one of the best developed and the most popular. The Orch OR model presumes that the microtubule network within neurons acts like a quantum computer. The tubulins are in superposition and the collapse of the wave function is driven by the quantum gravity. Penrose and Hameroff believe that conscious information is encoded in space-time geometry at the fundamental Planck scale and that a self-organizing Planck-scale process results in awareness.

M-theory

This approach by B. Flanagan builds on his work in mind/brain identity theory, positing an identity between photonic fields and their concomitant perceptual fields. Pointing to the symmetries and phase relations observed with color and sound, this work was extended to include considerations from Kaluza-Klein theory, gauge theory, fiber bundle theory, string theory, Chern-Simons theory and M-theory.

Quantum mysticism

The implications of Quantum mind theories have not been missed by believers of the paranormal, anxious for scientific justification of their beliefs. Some have claimed that quantum mechanics has eliminated the separation between mind, body and the world. The term "quantum consciousness" now shows up in the popular literature in connection with astrology, homeopathy, ghosts, angels, precognition, telepathy, alien abduction, acupuncture, and even how to achieve multiple orgasms. The writings of Fritjof Capra and Deepak Chopra have been instrumental in popularizing the view that there exists a connection between mysticism and quantum mechanics.

Criticisms

Broadly, the arguments against the possibility are:

First, comparatively large and high temperature items like neurons just do not exist in persisting states of linear superposition capable of exhibiting interference effects, and quantum mechanics offers no reason to think they should. All brain scale systems spend their time in well defined classical states; their behavior, even after interaction with thoroughly quantum systems like a decaying atoms, can be described perfectly well with ordinary probability calculus. It turns out that effective classicality extends, under almost all conditions, far below the neural level to that of medium-sized molecules.

Secondly, the truth of decoherence is that, regardless of whether there are any conscious observers around or not, objects which would be expected to behave in an essentially classical manner, do exactly that. Interaction between objects and their environments, both external and internal, does the job of 'observation' erroneously accorded only to conscious observers, effecting a process which is experimentally indistinguishable from state vector reduction.

Thirdly, none of the theories explains how the activity of single synapses enters the dynamics of neural assemblies, and they leave mental causation of quantum processes as a mere claim. Thus they are essentially unsatisfactory with regard to a sound formal basis and concrete empirical scenarios and lack compelling argument or evidence that requires that quantum mechanics play a central role in human consciousness.

Pseudonomenalism

Quantum theories of mind are among the few classes of theories acceptable in the philosophical stances of pseudonomenalism and mind/brain identity theory.

Many-minds interpretation

There is another type of quantum theory of mind called the many-minds interpretation that is invoked as a conservative version of the many-worlds interpretation of quantum theory and does not involve collapse of the QM wave function.

Consciousness causes collapse

Consciousness causes collapse is the speculative theory that observation by a conscious observer is responsible for the wavefunction collapse and that the process of measurement in quantum mechanics is consciousness itself.

Ongoing Debate

Ongoing Debate

Science

The main argument against the quantum mind proposition is that the structures of the brain are much too large for quantum effects to be important. It is impossible for coherent quantum states to form for very long in the brain and impossible for them to exist at scales on the order of the size of neurons. Price, for example, says that quantum effects rarely or never affect human decisions and that classical physics determines the behaviour of Neurons.

In quantum terms each neuron is an essentially classical object. Consequently quantum noise in the brain is at such a low level that it probably doesn't often alter, except very rarely, the critical mechanistic behaviour of sufficient neurons to cause a decision to be different than we might otherwise expect. (...)

Michael Clive Price[1]

This does not imply that classical mechanics can explain consciousness, but that quantum effects including superposition and entanglement are insignificant.

One well-known critic of the quantum mind is Max Tegmark. Based on his calculations, Tegmark concluded that quantum systems in the brain decohere quickly and cannot control brain function, "This conclusion disagrees with suggestions by Penrose and others that the brain acts as a quantum computer, and that quantum coherence is related to consciousness in a fundamental way"[22]

Proponents of quantum consciousness theories have sought to defend them against Tegmark's criticism. In respect of QBD, Vitiello has argued that Tegmark's work applies to theories based on quantum mechanics but not to those such as QBD that are based on quantum field theory. In respect of Penrose and Hameroff's Orch OR theory, Hameroff along with Hagan and Tuszynski replied to Tegmark[23]. They claimed that Tegmark based his calculations on a model that was different from Orch OR. It is argued that in the Orch OR model the microtubules are shielded from decoherence by ordered water. Energy pumping as a result of thermal disequilibrium, Debye layer screening and quantum error correction, deriving from the geometry of the microtubule lattice are also proposed as possible sources of shielding. Similarly, in his extension of Bohm's ideas, Bernroider has claimed that the binding pockets in the ion selection filters could protect against decoherence[4]. So far, however, there has been no experimental confirmation of the ability of the features mentioned above to protect against decoherence.

Philosophy

Another line of criticism is that no physical theory is well suited to explaining consciousness, particularly in its most problematical form, phenomenal consciousness or qualia, known as the hard problem of consciousness.[24] It is not so much that colours and tastes and feelings—qualia or secondary qualities—have been deliberately banished, but more that they cannot be captured in any mathematical description, which means they cannot be explicitly represented in physics, since all physical theory is expressed in mathematical language (as explained in Eugene Wigner's famous paper The Unreasonable Effectiveness of Mathematics in the Natural Sciences). If no physical theory can express qualia, no physical theory can fully explain consciousness. Replacing the mathematical apparatus of classical physics with the mathematical apparatus of quantum mechanics is therefore of no help in understanding consciousness, and indeed there is no known example of a quantum equation which encapsulates a taste or colour.

As David Chalmers puts it:

Nevertheless, quantum theories of consciousness suffer from the same difficulties as neural or computational theories. Quantum phenomena have some remarkable functional properties, such as nondeterminism and nonlocality. It is natural to speculate that these properties may play some role in the explanation of cognitive functions, such as random choice and the integration of information, and this hypothesis cannot be ruled out a priori. But when it comes to the explanation of experience, quantum processes are in the same boat as any other. The question of why these processes should give rise to experience is entirely unanswered. [25]

Other philosophers, such as Patricia and Paul Churchland and Daniel Dennett[26] reject the idea that there is anything puzzling about consciousness in the first place.

See also



Notes

References

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  • Bell, JS, "On the Problem of Hidden Variables in Quantum Mechanics." Reviews of Modern Physics, 38, 3, (1966).
  • Bohm, David. Quantum Theory. Englewood Cliffs, NJ: Prentice-Hall, Inc., 1951. see David Bohm for more of his relevant references.
  • Fröhlich, H., Long-range coherence and energy storage in biological systems. Int. Jour. of Quantum. Chem. II, 641-9, 1968.
  • Grossberg, Stephen. Studies of Mind and Brain. Dordrecht, Holland: D. Reidel, 1982.
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  • Jammer, Max. The Philosophy of Quantum Mechanics. New York, NY: John Wiley & Sons, 1974.
  • Lindberg, David C. Theories of Vision from Al-Kindi to Kepler. Chicago, IL: University of Chicago Press, 1976.
  • Lockwood, Michael. Mind, Brain and the Quantum. Cambridge, MA: Basil Blackwell Ltd., 1989.
  • McCulloch, Warren S. Embodiments of Mind. Cambridge, MA: The MIT Press, 1965.
  • Ne'eman, Yuval, ed. To Fulfill a Vision: Jerusalem Einstein Centennial Symposium on Gauge Theories and Unification of Physical Force. Addison-Wesley, 1981.
  • Pais, Abraham
    • Inward Bound. New York, NY: Oxford University Press, 1986.
    • Subtle is the Lord. New York, NY: Oxford University Press, 1982.
  • Penrose, Roger
    • The Emperor's New Mind. New York, NY: Oxford University Press, 1989.
    • Shadows of the Mind. New York, NY: Oxford University Press, 1994.
  • Pribram, Karl. Brain and Perception. Hillsdale, NJ: Lawrence Erlbaum, 1991.
  • Putnam, Hilary. Mathematics, Matter and Method. New York, NY: Cambridge University Press, 1975.
  • Russell, Bertrand
    • Analysis of Mind. New York, NY: Humanities Press, Inc., 1968.
  • Schrödinger, Erwin. Mind and Matter. Cambridge University Press, 1959.
  • Stapp, Henry P. Mind, Matter, and Quantum Mechanics, Springer-Verlag, 1993.
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  • Wigner, Eugene. "Physics and the Explanation of Life,"
  • Wikibook on consciousness

External links

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