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Penrose/Hameroff 1Penrose/Hameroff: 1 1.) The Emperor's New Mind - Roger Penrose 2.) Consciousness, Neurobiology & Quantum Mechanics - Stuart Hameroff The Emperor's New Mind Oxford University Press (1989) ISBN 0-19-286198-0 The 'Emperor's New Mind was the seminal book for what has since become the Penrose/Hameroff of Orch OR model of quantum consciousness. Penrose begins with a discussion of the extent to which computers and robots can be expected to manifest human-type intelligence and more especially consciousness. Penrose approaches the problem from a mathematical angle, and this makes the early part of the book difficult for the non-mathematical majority. Initially it can be hard to see how most of the material has relevance to the question of consciousness. However, persistence will be rewarded in a theory of consciousness that seems, in contrast to many mainstream theories, to have considerable explanatory power. Gödel’s Theorem The centre piece of the early part of the book is the discussion on Gödel's theorem. Gödel demonstrated that in any significant system of axioms there would be statements that were undecidable in terms of the axioms, but which were obviously true. The Gödel theorem as such is not controversial in relation to modern logic or mathematics, but the argument that Penrose derived from it has proved to be highly controversial. He claims that the fact that human mathematicians can see the truth of a statement that is not demonstrated by the axioms shows that the human mind contains some function that is not based on algorithms, and therefore could not be replicated by any computer, since the functioning of computers is based solely on algorithms. From Gödel, Penrose moves on to a straightforward account of physics, starting with classical physics, notably Galileo, and going onto relativity and quantum theory. This can be read as a useful popularisation of physics in its own right, but the real purpose of these chapters appears to be to establish the ground for Penrose’s claims about the relationship between physics and consciousness. Quantum Theory Penrose's discussion of quantum theory is particularly important in this respect. He implies criticism of the tendency in some quarters to try and marginalise quantum theory. He emphasises that quantum features underly many macroscopic phenomena such as solid objects, the physical properties of materials, colour, chemistry and DNA. But at the same time, he views present day quantum theory as a stop gap that does not provide a complete picture of the world. In particular, he disagrees with the traditional Copenhagen interpretation, which says that the theory is just an anstract calculational procedure and that the quanta only achieve objective reality when a measurement has been made. Reality somehow arises from the unreal or from abstraction, giving a dualist quality to the theory. The discussion of quantum theory repeatedly comes back to the theme that Penrose regards the quantum world, and the uncollapsed wave function as having objective existence. In Penrose's view, the objective reality of the quantum world allows the quantum world to play a role in consciousness. Penrose emphasises that the evolution of the wave function portrayed by this Schrödinger equation is both deterministic and linear. This aspect of quantum theory is not random. Randomness only emerges when the wave function collapses, and gives the choice of a particular position or other properties for a particle. Penrose discusses the various takes made on wave function collapse by physicists. Some would like everything to depend on the Schrödinger equation, but Penrose rejects this idea, because it is impossible to see how the mechanism of this equation could produce the transformation from the superposition of alternatives, as found in the quantum wave, to the random choice of a single alternative. He discusses the suggestion that the probabilities of the quantum wave that emerges into macroscopic existence arise from uncertainties in the initial conditions and that the system is analogous to chaos in macroscopic physics. This does not satisfy Penrose, who points out that chaos is based on non-linear developments, whereas the Schrödinger equation is linear. He also disagrees with Eugene Wigner’s suggestion that it is consciousness that collapses the wave function, on the basis that consciousness is only manifest in special corners of space and time. It is important to note this, as some commentators mix up Wigner’s idea with Penrose’s propositions on quantum consciousness, and then advance a refutation of Wigner as a supposed refutation of Penrose. He is also dismissive of the ‘many worlds’ version of quantum theory, which would have an endless splitting into different universes with, for instance, Schrödinger’s cat alive in one universe and dead in another universe. Penrose objects to the lack of economy and the multitude of problems that might arise from attempting such a solution, and in addition argues that the theory does not explain why the splitting has to take place, and why it is not possible to be conscious of superpositions. Penrose instead argues for an objective interpretation of the wave function collapse. If the superpositions described by the quantum wave extended into the macroscopic world, we would in fact see superpositions of large scale objects. As this does not happen, it is argued that something that is part of objective reality must take place to produce the reality that we actually see. Penrose takes the view here that what he is proposing requires some new physics. This is often criticised as an unjustified demand for a revolution in physics. However, these criticisms tend to ignore the fact that while quantum theory provides many accurate predictions there has never been satisfactory agreement about its interpretation, and some of its founders regarded the theory as only provisional. Penrose sees consciousness as not only related to the quantum level but also to spacetime, which means that it is related to relativity as well as quantum theory. This involves him in an extensive discussion of the origin of the universe. It is important to stress this, as the discussion of some of these areas does not seem immediately relevant to consciousness. Entropy and the second law of thermodynamics Penrose starts this stage of his argument by discussing the increase in entropy or disorder in the universe. He takes the example of a water glass falling from a table, shattering and the water pouring out onto the floor. The debris and spillage is more disordered than the previous structure of the water glass, and in addition some of the energy of the water and the glass has dispersed as heat. This is an example of increased entropy. Because the laws of physics are time symmetric, they in theory allow for the water and glass to reassemble themselves and lift themselves back onto the table. However, we never see this happen in real life, the reason being that it would require coordinated action amongst the molecules in the debris to happen by chance, and the odds against this are vanishingly small. The importance of this example is that in practise it represents an irreversible process in which entropy can only increase. This principle is encapsulated in the second law of thermodynamics, and is at least related to the arrow or flow of time. Another way of looking at the entropy question is that many fewer possible arrangements of particles are compatible with the organised state of a glass containing water than are compatible with the debris on the floor. What is interesting to Penrose however is what this seems to tell us about the early state of the universe. If entropy is continually increasing it must have been much lower at the beginning of the universe. Penrose poses the question as to why it was that entropy was so low in the early universe. Normally if a system has experienced low entropy that has subsequently increased, it means that the entropy was somehow constrained to be low in the past, and then later released from that constraint. Penrose looks for the source of the low entropy of the early universe. In respect of this, he considers life on Earth and its dependence on energy drawn from the sun. Penrose concludes that gravitational contraction in the sun and other stars has created high entropy. The stars formed from diffuse gas that had little gravitational clumping, and therefore constituted a reserve of low entropy. This diffuse gas derived from the Big Bang itself. The fact that the gas was distributed uniformly through space indicates a low level of entropy in the early universe, which in turn gives us the second law of thermodynamics. Penrose notes that there was low entropy despite the fact that the evidence of the background microwave radiation is that the early universe was near to thermal equilibrium, which would normally indicate high entropy. However, in this case, the entropy of the thermal equilibrium was more than offset by the low entropy related to the lack of gravitational clumping. Penrose argues that the singularity of the Big Bang is quite different from the singularities of black holes, which represent very high entropy because of gravity, and still more different from the mass of congealing black holes that would arise if, as in some cosmological scenarios, the whole universe were to collapse back to a future singularity. So we have low entropy at the beginning of the universe but high entropy at one version of the end of the universe and at intermediate black holes. Spacetime Curvature Penrose moves on to the question of the spacetime curvature described in general relativity. He looks at the effect of singularities relative to two spacetime curvature tensors, Weyl and Ricci. Weyl represents the tidal effect of gravity by which the part of a body nearest to the gravitational source falls fastest creating a tidal distortion in the body. Ricci represents the inward pull on a sphere surrounding the gravitational force. In a black hole singularity, the tidal distortion of Weyl would predominate over Ricci, and Weyl goes to infinity at the singularity. However, in an early universe expanding from the Big Bang, the inward tidal distortion is absent, so Weyl=0, while it is the inward pressure of Ricci that predominates. So the early universe is seen to have had low entropy and Weyl close to zero. Weyl is related to gravitational distortions, and Weyl close to zero indicates a lack of gravitational clumping, just as Weyl at infinity indicated the gravitational collapse into a black hole. Weyl close to zero and low gravitational clumping therefore indicate low entropy at the beginning of the universe. The fact the Weyl is constrained to zero is seen by Penrose as a function of quantum gravity. The whole theory is referred to as the Weyl curvature hypothesis or (WCH). The question that Penrose now asks is as to why initial spacetime singularities have this structure. Penrose points out that at the beginning of the 20th century quantum theory provided a solution for infinities in electro-magnetic theory. He thinks that quantum theory also has to help the problem of the infinity of singularities. This would be a quantum theory of the structure of spacetime, or in other words a theory of quantum gravity. However, although Penrose looks for the solution to his problem in quantum theory, he also says that quantum theory itself may have to change to take account of relativity. Penrose regards the problems of quantum theory in respect of the disjuncture between the Schrödinger equations deterministic evolution and the randomness in wave function collapse as fundamental. He thinks in terms of a time-asymmetrical quantum gravity, because the universe is time asymmetric from low to high entropy. He argues that the normal process of collapse of the wave function is time-asymmetric. He describes an experiment where light is emitted from a source and strikes a half-silvered mirror with a resulting 50% probability that the light reaches a detector and 50% that it hits a darkened wall. This experiment cannot be time reversed, because if the original emitter now detects an incoming photon, there is not a 50% probability that it was emitted by the wall, but instead 100% probability that it was emitted by the other detecting/emitting device. Penrose has a section which seeks to relate the loss of information that occurs in black holes to the quantum mechanical effects of the black hole radiation described by Stephen Hawking. This relates the Weyl curvature that is seen to apply in black holes and the quantum wave collapse. As Weyl curvature is related to the second law of thermodynamics, this is taken to show that the quantum wave reduction is related to the second law and to gravity. Towards objective reduction Penrose does not develop his objective reduction (OR) idea until his second book, but he does feel his way towards the general concept in this book. He points out that there have always been technical difficulties in relating the discrete concepts of quantum mechanics to the curvature of spacetime as described in relativity. He suggests that the quantum linear superposition of the Schrödinger wave can be expected to fail as soon as spacetime curvature becomes significant. He thinks it is at this point that the probability-weighted alternative is chosen from amongst complex amplitude superpositions. The amount of spacetime curvature involved is equivalent to one graviton, the quantisation of the gravitational field, the smallest unit of curvature allowed in a quantised theory. It is suggested that once this level of curvature is reached there is some form of time-asymmetric instability that allows one of the alternative probabilities to win out over the others. These suggestions are reformulated in the more specific and testable objective reduction theory in Penrose’s second consciousness related book, ‘Shadows in the Mind.’ Penrose’s ideas as to how quantum processes might be instantiated in the brain are not really developed until ‘Shadows in the Mind’, which demonstrated the influence of his cooperation with Stuart Hameroff. In the last part of the book, he merely reiterates that non-algorithmic processes might have a role in the brain, and adds to this that some as yet undescribed version of the quantum wave reduction could contain such a non-algorithmic element, and possibly allow the mind to form a bridge between physical reality and the abstract world of mathematics. As a whole, this book represents an early and tentative stage of the development of the Penrose/Hameroff model. The book does not contain the idea of objective reduction (OR), which later on became central to the model. OR could be seen as a read out from the fundamental space time geometry of the universe, but this was to come later in Penrose's second book, 'Shadows of the Mind'. Even more crucially, when this book was written, Penrose, who lacked a neuroscientic background, had no model for how the brain could support quantum coherent activity or if this did exist, how it would function as a basis of consciousness. References:- Baylor, D., Lamb, T., & Yau, K. (1979) Responses of retinal rods to single photons Journal of Physiology, 288, pp. 613-34 Bekenstein, J. (1972) Black holes and entropy Physics Review, D7, pp. 2333-46 Deeke, L., Groetzinger, B. & Kornhuber, H. (1976) Voluntary finger movements Biological Cybernetics, 23, 99 Dennett, D. (1978) Brainstorms Penguin Deutsch, D. (1985) Quantum theory, the Church-Turing principle and the universal quantum computer Proceedings of the Royal Society London, A400, pp. 97-117 Gardner, M. (1989) Penrose tiles to trapdoor cyphers W.H. Freeman & Company Geroch, R. & Hartle, J. (1986) Computability and physical theories Foundation Physics, 16, 533 Ghiradi, G., Rimini, A. & Weber, T. (1980) A general argument against superluminal transmission Lett. Nuovo Chim., 27, pp. 293-8 Ghiradi, G., Rimini, A. & Weber, T. (1986) Unified dynamics for microscopic and macrosccopic systems Physics Review, D34, 470 Good, I. (1969) Goedel's theorem is a red herring British Journal of Philos.Science, 18, pp. 359-73 Gruenbaum, B. & Shepherd, G (1987) Tilings and patterns W.H. Freeman Hanf, W. (1974) Non-recursive tilings of the plain International Journal of Symbolic Logic, 39, pp. 283-5 Hartle, J. & Hawking, S. (1983) Wave function of the universe Physics Review, D31, 1777 Hawking, S. (1975) Particle creation by black holes Commun. Math. Phys., 43, pp. 199-220 Hawking, S. (1987) Quantum cosmology In Hawking, S. & Israel, W. Eds. In 300 Years of Gravitation Cambridge University Press Hawking, S. & Penrose, R. (1970) The singularities of gravitational collapse and cosmology Proceedings of the Royal Society London, A314, pp. 529-48 Huggett, S. & Tod, K. (1985) An Introduction to Twistor Theory London Mathematical Society Cambridge University Press Karolyhazy, F. (1974) Gravitation and quantum mechanics in macroscopic bodies Magyar Fisikai Folyoirat, 12, 24 Karolyhazy, F., Frenkel, A. & Lukacs, B. (1986) On the possible role of gravity on the reduction of the wave function In Penrose, R. & Isham, C. Eds. Quantum Concepts in Space and Time Komar, A. (1964) Undecidability of macroscopically distinguishable states in quantum field theory Physics Review, 133B, pp. 542-4 Komar, A. (1969) Qualitative features of quantised gravitation International Journal of Theoretical Physics, 2, pp. 157-60 Lucas, J. (1961) Minds, Machines and Goedel Philosophy, 36, pp. 120-4 Myers, D. (1974) Nonrecursive tilings of the plain II Journal of Symbolic Logic, 39, pp. 286-94 Nagel, E., & Newman, J., (1958) Goedels Proof Routledge & Kegan Paul Onada, G. et al (1988) Growing perfect quasicrystals Physical Review Letters, 60, 2688 Penfield, W. & Jasper, H. (1947) Highest level seizures Research Publications of the Association for Research in Nervous and Mental Diseases, 26, pp. 252-71 Penrose, R. (1965) Gravitational collapse and space time singularities Physical Review Letters, 14, pp. 57-59 Penrose, R. (1974) The role of aesthetics in pure and applied mathematical research Bulletin of the Institute of Mathematical Applications, 10, no. 7/8, pp. 266-71 Penrose, R. (1979a) Einstein's vision and the mahtematics of the natural world The Sciences, March, 6-9 Penrose, R. (1979b) Singularities and time-asymmetry In Hawking, S & Israel, W. Eds. General Relativity Cambridge University Press Penrose, R. (1987a) Newton, quantum theory and reality In Hawking, S. & Isreal, W. Eds. 300 Years of Gravity Cambridge University Press Penrose, R. (1987b) Quantum physics and conscious thought In Hiley, B. & Peat, F. Eds. Essays in Honour of david Bohm Routledge and Kegan Paul Penrose, R. (1989a) Tilings and quasi-crystals In Jaric, M. Ed. Aperiodicity and Order Academic Press Penrose, R. (1989b) Difficulties with inflationary cosmology In Fenyves, E. Ed. Symposium on Relativistic Astrophysics New york Academy of Science Penrose, R. & Rindler, W. (1986) Spinor and twistor methods in space-time geometry Cambridge University Press Robinson, R. (1971) Undecidability and nonperiodicity for tilings of the plane Invent. Math., 12, pp. 177-209 Searle, J. (1980) Minds, brains and programs In Hofstadter, R. & Dennett, D. Eds The Behavioural and Brain Sciences Penguin Ward, R. & Wells, R. (1990) Twistor geometry and field theory Cambridge University Press Weiskrantz, L. (1987) Neuropsychology and the nature of consciousness In Blakemore, C. & greenfield, S. Mindwaves Blackwell Consciousness, Neurobiology & Quantum Mechanics: The Case for Connection Stuart Hameroff In: The Emerging Physics of Consciousness, Ed. J. Tuszynski Springer, 2006 ISBN-13 978-3-540-23890-4 Hameroff classifies all the mainstream approaches to consciousness as 'classical functionalism'. Functionalism takes no account of what the brain is made of or of anything finer grained than the level of neuron-to-neuron connections. It believes that these connections could be copied in another material such as silicon, and that the resulting construct would be conscious. However, Hameroff argues that although axonal spikes and synaptic connections clearly play a key role in information processing in the brain, they may not be the main currency of consciousness. Hameroff argues that quantum processing in microtubules within the dendrites and gap junctions between dendrites are the main currency of consciousness. The main case against quantum processing in the brain has always been that any quantum coherence in the brain would decohere faster than the time taken for any useful biological process. Hameroff accepts that this is in principle a valid argument. However, Hameroff claims that the microtubules may be screened from their environment by a gelatinous non-liquid ordered state that arises in the neuronal interior. A further objection to quantum processing is that even if it arose in one neuron, it would difficult for it to communicate across the brain. This is countered by the suggestion that there could be quantum tunneling at gap junctions between neurons. In recent years, gap junctions have been discovered to be more widespread in the brain than was previously thought. They are also correlated with the 40Hz gamma synchrony. This oscillation was at one time promoted by Crick and Koch as the most promising correlate of consciousness. However, the idea fell from favour with mainstream neuroscience, when it was discovered that the gamma synchrony correlated with dendritic activity rather than axonal spiking. In general, Hameroff argues that the emerging evidence of neurobiology has moved in favour of the Orch OR model over the last decade, not withstanding the continued unpopularity of the theory. Hameroff summarises his proposals in the early part of the chapter. He thinks that consciousness arises in the dendrites of neurons that are connected by gap junctions to form 'hyperneurons', and that these are related to the gamma synchrony. Axonal spikes and synapses are seen as making inputs to and receiving outputs from the microtubular process as part of an interactive systems. Backward Referral in Time Hameroff touches on the famous Libet experiments that demonstrated a 500ms timelag between a stimulus and the perception of it entering consciousness, although the subject is not aware of this time lag, as a result of a so-called backward referral in time. The mainstream has tended to favour an interpretation resembling the Dennett 'multiple drafts' concept, which would involve an after the event reconstruction of what had happened. Hameroff, however, thinks that the backward referral in time should be taken seriously. This was also the view of Roger Penrose, who suggested that backward referral might be indicative of quantum activity. Dendrites, Gap Junctions & the Gamma Synchrony Hameroff points out that changes in dendrites can lead to increased synaptic activity. This is basic to ideas about learning, memory and neural correlates of consciousness. The changes in dendrites involve the number and arrangement of receptors and the arrangement of dendritic spines and dendrite-to-dendrite connections. Axon potentials or spikes have been assumed to be the main basis of consciousness, but Hammerof suggests that there could be other candidates. Electrodes implanted into the brain detect mainly the activity of dendritic gap junctions plus inhibitory chemical synapses. Thus the detected synchrony derives from dendrites rather than axonal spikes. The main function of dendrites is seen to be the handling of input signal into the neuron, which may eventually result in an axon spike. However, this is not the whole story, since many cortical neurons have dendrites but no axons. Here dendrites interact with other dendrites. Also there can be extensive dendritic activity with no spikes. The evidence suggests that there are complex logic functions in the dendrites, and these may oscillate over a wide area, while remaining below the axon spiking threshold. Many post-synaptic receptors send signals into the dendrite cytoskeleton. Gamma synchronies, in the 30-70Hz range, have aroused interest as possible correlates of consciousness. Gray and Singer (1) found coherent gamma oscillations in the brain that were dependent on visual stimulation. It was suggested that this synchrony could solve the binding problem, which is the problem of how the different inputs into the brain are bound together into a single conscious experience. It was suggested that the synchrony relected the activity of a relevant assembly of neurons. Varela (2) noted that synchrony operated whenever the processing of spatially separated parts of the brain were brought together in consciousness. Gamma synchrony has been demonstrated across cortical areas, hemispheres and the sensory/motor modalities. The synchrony is involved in a range of brain activities including perception of sound, REM dream sleep, attention, working memory, face recognition and somatic perception. Also gamma decreases during general anesthesia and returns on waking from this. Hameroff regards gamma synchrony as the best overall correlate of consciousness. He further addresses the question of how the gamma synchrony is mediated. There is coherence over large areas of the brain, sometimes including multiple cortical areas and both hemispheres of the brain, with zero or near zero phase lag. If the synchrony was based on the axon/synapse system a considerable lag would be expected. In fact, the lack of coherence between the synchrony and axonal spike activity has led to a reduction in the amount of mainstream attention paid to the gamma synchrony. Hameroff points to gap junctions as an alternative to synapsses for connections between neurons. Neurons that are connected by gap junctions depolarise synchronously. Gap junctions play a more important role in the adult brain than was previously supposed. Numerous studies (3) show that gap junctions mediate the gamma synchrony. A neuron may have many gap junction connections but not all of them are necessarily open at the same time. The opening and closing of the junctions may be regulated by the microtubules. Hameroff suggests that cells connected by gap junctions may in fact constitute a cell assembly, with the added advantage of snchronous excitation. Cortical inhibitory neurons are heavily studded with gap junctions, possibly connecting each cell to 20 to 50 others (4). The axons of these neurons tend to form inhibitory GABA chemical synapses on the dendrites of other interneurons. Hameroff moves on to discuss the role of the cytoskeleton, which is seen to determine the structure, growth and function of neurons. Actin is the main constituent of dendritic spines and is present throughout the neuronal interior. Actin can depolymerise into a dense meswork, and when this happens the interior of the cell is converted from an aqueous solution into a gelatinous state. Furthermore, when this happens the whole of the cytoskeleton forms a negatively charged matrix around which water molecules are bound into an ordered state (5). It is noted that the neurotransmitter glutamate binding to NMDA and AMPA receptors cause gel states in actin spines (6). The cytoskeleton of the dendrites is distinct both from that found in cells outside the brain and from the cytoskeleton found in the axons of neurons. The microtubules in dendrites are shorter than those in axons and have mixed as opposed uniform polarity. This appears a sub-optimal arrangement from a normal structural point of view, and it is suggested that in conjunction with microtubule associated proteins (MAPs), this arrangement may be optimal for information processing rather than supportive structural functions. These microtubule/MAP arrangements are connected to synaptic receptors on the dendrite membrane by a variety of calcium and sodium influxes, actin and other inputs (7). Alterations in the microtubule/MAPs network in the dendrites correlate with the arrangement of dendrite synapatic receptors (8). Studies (9) demonstrate that the cytoskeleton is also involved in signal transmission. It is suggested that the microtubule lattice is well designed to represent and process information. Tubulin switches between two conformations. It is suggested that tubulin conformational states could interact with with neighbouring tubulin by means of dipole interactions. The dipole-coupled conformation for each tubulin could be determined by the six surrounding tubulins. Hameroff describes protein conformation as a delicate balance between contervailing forces. Proteins are chains of amino-acids that fold into three dimensional conformations. Folding is driven by van der Waals forces between hydrophobic amino-acid groups. These groups can form hydrophobic pockets in some proteins. These pockets are critcal to the folding and regulation of protein. Amino acid side groups in these pockets interact by van der Waals forces. Nonpolar atoms and molecules can have instantaneous dipoles. Hameroff discusses the process of anesthesia which erases consciousness, but leaves many non-conscious functions intact. Anesthetic gas molecules are soluble in a lipid-like hydrophobic environment. Such areas are present in the brain in the lipid regions of cell membranes and in hydrophobic pockets within proteins. It is suggested that anesthetic gas molecules interact with amino-acid groups via London forces, altering the normal action of London forces on the conformation of protein. Hameroff discusses quantum information processing. Quantum superpositions where the quantum waves represent multiple possibilities for the state of a particle, are known to persist until quanta are either measured or naturally interact with the rest of the environment. Hameroff takes the view that the original mainstream interpretation, Copenhagen Interpretation, puts not only consciousness but the concept of reality itself outside physics. Alternatives interpretations include the 'many worlds' view, where there is no collapse but the superpositions continue in multiple worlds and David Bohm's idea in which the quanta are guided by active information. Penrose's own tke on the wave function collapse suggests that it is a real event. He sees superposition as a separation in the underlying space-time geometry. Each quanta is embedded in a bit of space, and as the superpositions grow further apart, a blister or separation appears in space-time. This can be viewed as the same thing as the beginning of the multiple world view, but instead of going on to generate separate universes, if the separation between superpositions grows to more than the Planck length, the wave collapses and chooses one of the superposed alternatives. The normal quantum wave collapse is seen as an entirely random choice of the state of a quantum particle, from amongst the various superpositions of states. However, these collapses involve interaction with the environment. Penrose suggests that a quanta, which does not interact with the environment will undergo objective reduction (OR) when the separation between superpositions begins to exceed the Planck length. He also suggests that while the normal collapse is totally random OR is not totally random but involves a non-computable process. This is suggested because Penrose thinks that the brain manifests a non-computational aspect, and that the wave function collapse is the only place in the universe where such a thing can exist. Penrose also proposes that OR based quantum computation occurs in the brain. It is important to stress that quantum computing as such is not expected to generate consciousness. In quantum computers, which many researchers, are now trying to develop quantum collapse will occur as a result of measurement or interaction with the environment. It is only in the event of OR that non-computability and consciousness could be brought into play. Hameroff goes on to look at some of the detail of the theory that he and Penrose developed as to how consciousness could be based in microtubules in the brain. It is suggested that quantum compuations take place in microtubules orchestrated by the inputs of synapse via MAPs. Hence the theory is often known as Orch OR for orchestrated objective reduction. The computations are suggested to persist for 25 ms, which would link them to the 40Hz gamma synchrony, viewed as a correlate of consciousness even in more mainstream theories. The computations are terminated by objective reduction. It is proposed that in dendrites, the tubulin sub-units of the microtubules interact by dipole coupling so as process information. The tubulin conformation is governed by quantum London forces, so that the tubulins can exist as quantum superpositions of different conformations. In superposition the tubulins would be qbits in a quantum computer, computing by means of non-local entanglement with other tubulin qbits. This entanglement would not just be with tubulins in the same microtubule, but other microtubules in the same dendrite, and in other dendrites connected by gap junctions. Neurons connected by gap junctions can be viewed as a single hyperneuron, and the hyperneuron can be seen as a conventional neuron assembly. The dendritic interiors alternate between two states as a result of the polymerisation of actin protein. In the depolymerised form the interior of the neuron is aqueous and microtubules signal and process information classically. There are synaptic inputs to the microtubules during this phase. When actin polymerises the interior of the dendrite becomes quasi-solid of gelatinous, and water near to the proteins becomes ordered as a result of the actin gelation. Debye layers of counterions may also shield the microtubules, due to the charged C-termini tails on the tubulins. This is suggested to make the microtubules sufficiently isolated from the environment for quantum superposition to occur in the tubulins. The geometry of a quantum computer lattice could be formed so as to be resistant to decoherence. Microtubules are suggested to have a structure which is particularly suitable for error correction. Coherent pumping of energy and quantum error correction may thus help to prevent decoherence. Quantum error correction involves a code that can detect and correct decoheence in a quantum system. Hameroff claims to refute Tegmark's attempt to disprove the Penrose/Hameroff model. This is significant as Tegmark's criticism of Orch OR has been widely accepted as a completely satisfactory dismissal of the theory, and responses to Tegmark are habituaaly ignored. Tegmark calculated microtubule decoherence time as being 10^-13 seconds, which would certainly be much too short for any neural activity. However, he worked on the basis of his own model for quantum activity in microtubules, which was never proposed by Hameroff or anyone else, basing his calculation on a 24nm separation of solitons from themselves along the microtubules, whereas Orch OR proposes a superposition separation distance six orders of magnitude smaller. For some reason, Tegmark did not choose to address the Penrose/Hameroff model. This invalidates his particular approach, whatever the truth is about decoherence, but it has not prevented his work from being quoted as an absolutely reliable refutation of Orch OR. Capability of Being or Falsified The ability of a theory to be falsified is the acid test of a scientific theory. The Orch Or model is claimed to stand up well in this respect. In 1998 twenty testable predictions of Orch OR were published. Four of these have actually been validated over the last decade, being, signalling along microtubules (9), correlation of synaptic function and cytoskeleton (10), action of psychoactive drugs on microtubules (11) and gap junction mediation of gamma synchrony (12). Others are currently being tested. The 16 untested predictions are:- 1) Microtubule stabilising drugs could treat brain diseases (13). 2) Laser spectroscopy could demonstrate coherent oscillation in microtubules (14). 3) Correlation of vibrational states of microtubule networks with cell activity. 4) Correlation of cytoskeletal networks with memory and neural behaviour 5) Preponderance of 'A lattice' microtubules in dendrites, as these are more suited to information processing. 6) Demonstration of non-local correlations between tubulins on same and different microtubules. 7) Superconducting devices could detect quantum coherence in microtubules. 8) Coherent photons will be detected from microtubules. 9) Dendritic microtubules surrounded by cross linked actin gels. 10) Cycles of gelation linked to gamma synchrony. 11) Gelation cycles regulated by calcium ions associated with microtubules. 12) Quantum tunnelling across gap junctions. 13) Non-local correlation between tubulins in different neurons. 14) Neural mass involved in cognitive tasks is inversely proportional to pre-conscious time, as in E=hbar/t. 15) Gap junction connections with retinal glial cells. 16) Testing of objective reduction (OR). Experiments will test if isolated quantum superpositions self-collapse according to E=hbar/t (15). The theory is 'fundamentalist' in assuming that consciousness has to be a fundamental property of the universe that is accessed by the brain. Penrose's OR relates to the fundamental level of the universe, where at 10^-35 m. the continuity of space-time breaks down and becomes quantised. This is proposed as the level where non-computable processes and possibly qualia are embedded. The rarity of consciousness in the universe is because only in a structure like the brain is it possible to isolate relatively large superpositions, such as nanograms of tubulin. References:- 1) Gray, C. & Singer, W. (1989) Proceedings of the National Academy of Sciences USA, 86, 1698-1702 2) Varela, F. (1995) Biological Research, 28, 81-95 3) Dermietzel, R. 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