MXPlank - The Elegant Universe Of Space-Time

Quantum Consciousness

An approach to the mind-body problem based on physical laws has been advocated by several thinkers. Quantum Theory has been particularly intriguing for scientists eager to provide a physical explanation of consciousness.

Loosely speaking, the point is that consciousness is unlikely to arise from classical properties of matter (the more we understand the structure and the fabric of the brain, the less we understand how consciousness can occur at all), which are well known and well testable. But Quantum Theory allows for a new concept of matter altogether, which may well leave cracks for consciousness, for something that is not purely material or purely extra-material. Of course, the danger in this way of thinking is to relate consciousness and Quantum only because they are both poorly understood: what they certainly have in common is a degree of "magic" that makes both mysterious and unattainable...

On the other hand, it is certainly true that all current neurobiological descriptions of the brain are based on Newton's Physics, even if it is well known that Newton's Physics has its limitations. First of all, Newton's Physics is an offshoot of Descartes division of the universe in matter and spirit, and it deals only with matter. Secondly, neurobiologists assume that the brain and its parts behave like classical objects, and that quantum effects are negligible, even while the "objects" they are studying get smaller and smaller. What neurobiologists are doing when they study the microstructure of the brain from a Newtonian perspective is equivalent to organizing a trip to the Moon on the basis of Aristotle's Physics, neglecting Newton's theory of gravitation.

No wonder most neurobiologists reach the conclusion that Physics cannot explain consciousness, since they are using a Physics that 1. was designed to study matter and leave out consciousness and that 2. does not work in the microworld. Not surprisingly, it has been claimed that all current neurobiological models are computationally equivalent to a Turing machine.

The true pioneer of this field is the biologist Alfred Lotka, who in 1924, when Quantum Theory had barely been born, proposed that the mind controls the brain by modulating the quantum jumps that would otherwise lead to a completely random existence.

The first detailed quantum model of consciousness was probably the American physicist Evan Walker's synaptic tunneling model (1970), 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 produces consciousness and that can direct the behavior of the real nervous system. The real nervous system operates by means of synaptic messages. The virtual one operates by means of the quantum effect of tunneling (particles passing through an energy barrier that classically they should not be able to climb). The real one is driven by classical laws, the virtual one by quantum laws. Consciousness is therefore driven by quantum laws, even if the brain's behavior can be described by classical laws.

A few researchers have invoked another quantum effect, Bose-Einstein condensation (theoretically predicted in 1925 and first achieved in a gas in 1995), which is a general case of superconductivity. A Bose-Einstein condensate is the equivalent of a laser, except that it is the atoms, rather than the photons, that behave identically. Its atoms behave like they were a single atom. Technically speaking, as temperature drops each atom's wave grows, until the waves of all the atoms begin to overlap and eventually merge. After they merged, the atoms are located within the same region in space, they travel at the same speed, they vibrate at the same frequency, etc.: they become indistinguishable. The atoms have reached the lowest possible energy, but Heisenberg's principle makes it impossible for this to be zero energy: it is called "zero-point" energy, the minimum energy an atom can have. The intriguing feature of a Bose-Einstein condensate is that the many parts of a system not only behave as a whole, they become whole. Their identities merge in such a way that they lose their individuality.

In 1986 the British physicist Herbert Froehlich suggested that such condensation can be achieved in Nature by biological organisms. In particular, it should arise when biological oscillators which are in a nonequilibrium state (such as all plants and animals) are maintained at constant temperature. Biological oscillators of this kind are pervasive in nature: living matter is made of water and other biomolecules equipped with electrical dipoles, which react to external stimuli with a spontaneous breakdown of their rotational symmetry. The biological usefulness of such biological oscillators is that, like laser light, they can amplify signals and encode information (e.g., they can "remember" an external stimulus).

In 1989 the British phychiatrist Ian Marshall showed similarities between the holistic properties of condensates and those of consciousness, and suggested that consciousness may arise from the excitation of such a Bose-Einstein condensate. In Marshall's hypothesis, the brain contains a Froelich-style condensate, and, whenever the condensate is excited by an electrical field, conscious experience occurs. The brain would maintain dynamical coherence thanks to an underlying quantum coherent state (due, precisely, to the properties of such a condensate).

Drawing from Quantum Mechanics and from Bertrand Russell's idea that consciousness provides a kind of "window" onto the brain, the philosopher Michael Lockwood advanced a theory of consciousness as a process of perception of brain states.

First he noted that Special Relativity implies that mental states must be physical states (mental states must be in space given that they are in time). Then Lockwood interpreted the role of the observer in Quantum Mechanics as the role of consciousness in the physical world (as opposed to a simple interference with the system being observed). Lockwood argued that sensations must be intrinsic attributes of physical states of the brain: in quantum lingo, each observable attribute (e.g., each sensation) corresponds to an observable of the brain. Consciousness scans the brain to look for sensations. It does not create them, it just seeks them.

In 1986 John Eccles, the British neurophysiologist who discovered neurotransmitters, has speculated that synapses in the cortex respond in a probabilistic manner to neural excitation, a probability that could well be governed by quantum uncertainty given the extremely small size of the synapsis'"microsite" that emits the neurotransmitter. If this is true, Eccles speculates that an immaterial mind (in the form of "psychons") controls the quantum "jumps" and turns them into voluntary excitations of the neurons that account for body motion.

Conscious matter

The American physicist Nick Herbert has been even more specific on the similarities between Quantum Theory and consciousness. Herbert thinks that consciousness is a pervasive process in nature. Mind is as fundamental a component of the universe as elementary particles and forces. Mind can be detected by three features of quantum theory: randomness, thinglessness (objects acquire attributes only once they are observed) and interconnectedness (John Bell's discovery that once two particles have interacted they remain connected). Herbert thinks that these three features of inert matter can account for three basic features of mind: free will, essential ambiguity, and deep psychic connectedness. Scientists may be vastly underestimating the quantity of consciousness in the universe.

The computer scientist James Culbertson, a pioneer of research on robots, has even speculated that consciousness may be a relativistic feature of spacetime. In his opinion, too, consciousness permeates all of nature, so that every object has a degree of consciousness.

According to Relativity, our lives are world lines in spacetime. Spacetime does not happen, it always exists. It is our brain that shows us a movie of matter evolving in time.

All spacetime events are conscious: they are conscious of other spacetime events. The "experience" of a spacetime event is static, a frozen region of spacetime events. All the subjective features of the "psychospace" of an observer can be completely derived from the objective features of the region of spacetime that the observer is connected to. Special circuits in our brain create the impression of a time flow, of a time travel through the region of spacetime events connected to the brain.

Memory of an event is re-experiencing that spacetime event, which is fixed in spacetime. We don't store an event, we only keep a link to it. Conscious memory is not in the brain, is in spacetime.

The inner life of a system is its spacetime history. To clarify his view, Culbertson presents the case of two robots. First a robot is built and learns German, then another robot is built which is identical to the first one. Culbertson claims that the second robot does not speak German, even if it is identical to the one which speaks German. Their spacetime histories are different.

At the same time, Culbertson thinks that our consciousness is much more than an illusory travel through spacetime, and it can, in turn, influence reality. Quantum Thoery prescribes that reality be a sequence of random quantum jumps. Culbertson believes that they are not random but depend on the system's spacetime history, i.e. on its inner life.

Tripartite Idealism

The American physicist Henry Stapp holds that classical Physics cannot explain consciousness because it cannot explain how the whole can be more than the parts. In Quantum Mechanics, on the other hand, the relationship between the parts and the whole is completely different. Stapp therefore advances a "quantum theory of consciousness" and bases it on Heisenberg's interpretation of Quantum Mechanics (that reality is a sequence of collapses of wave functions, i.e. of quantum discontinuities). He observes that this view is similar to William James's view of the mental life as "experienced sense objects".

His view harks back to the heydays of Quantum Theory, when it was clear to its founders that "science is what we know". Science specifies rules that connect bits of knowledge. Each of us is a "knower" and our joint knowledge of the universe is the subject of Science. Quantum Theory is therefore a "knowledge-based" discipline. This view was "pragmatic" because it prescribes how to make experiments, and it was separating the system to be observed from the observer and from the instrument.

Von Neumann introduced an "ontological" approach to this knowledge-based discipline, which brought the observer and the instrument in the state of the system. Stapp describes Von Neumann's view of Quantum Theory through a simple definition: "the state of the universe is an objective compendium of subjective knowings". This statement describes the fact that the state of the universe is represented by a wave function which is a compendium of all the wave functions that each of us can cause to collapse with her or his observations. That is why it is a collection of subjective acts, although an objective one.

Stapp follows the logical consequences of this approach and achieves a new form of idealism: all that exists is that subjective knowledge, therefore the universe is now about matter, it is about subjective experience. Quantum Theory does not talk about matter, it talks about our perceiving matter. Stapp rediscovers George Berkeley's idealism: we only know our perceptions (observations).

Stapp's model of consciousness is tripartite. Reality is a sequence of discrete events in the brain. Each event is an increase of knowledge. That knowledge comes from observing "systems". Each event is driven by three processes that operate together:

The "Schroedinger process" is a mechanical, deterministic, process that predicts the state of the system (in a fashion similar to Newton's Physics: given its state at a given time, we can use equations to calculate its state at a different time). The only difference is that Schroedinger's equations describe the state of a system as a set of possibilities, rather than just one certainty.
The "Heisenberg process" is a conscious choice that we make: the formalism of Quantum Theory implies that we can know something only when we ask Nature a question. This implies, in turn, that we have a degree of control over Nature. Depending on which question we ask, we can affect the state of the universe. Stapp mentions the Quantum Zeno effect, as a well known process in which we can alter the course of the universe by asking questions (it is the phenomenon by which a system is "freezed" if we keep observing t he same observable very rapidly). We have to make a conscious decision about which question to ask Nature (which observable to observe). Otherwise nothing is going to happen.
The "Dirac process" gives the answer to our question. Nature replies, and, as far as we can tell, the answer is totally random.

Once Nature has replied, we have learned something: we have increased our knowledge. This is a change in the state of the universe, which directly corresponds to a change in the state of our brain. Technically, there occurs a reduction of the wave function compatible with the fact that has been learned.

Stapp's interpretation of Quantum Theory is that there are many knowers. Each knower's act of knowledge (each individual increment of knowledge) results in a new state of the universe. One person's increment of knowledge changes the state of the entire universe, and, of course, it changes it for everybody else.

Quantum Theory is not about the behavior of matter, but about our knowledge of such behavior.

"Thinking" is a sequence of events of knowing, driven by those three processes.

Instead of dualism or materialism, one is faced with a sort of interactive "triality", all aspects of which are actually mind-like:

The physical aspect of Nature (the Schroedinger equation) is a compendium of subjective knowledge. The conscious act of asking a question is what drives the actual transition from one state to another, i.e. the evolution of the universe. And then there is a choice from the outside, the reply of Nature, which, as far as we can tell, is random.

Stapp's conclusions somehow mirror the ideas of the American psychiatrist Jeffrey Schwarz, who is opposed to the mechanistic approach of Psychiatry and emphasizes the power of consciousness to control the brain.

Stapp revives idealism by showing that Quantum Theory is about knowledge, not matter. The universe is a repository of knowledge, that we have access to and upon which our consciousness has control.

Holonomic Consciousness

The "holonomic" model of memory, advanced by psychologist Karl Pribram, is based on the 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.

Holograms are the product of a physical process that preserves the three-dimensional quality of an object. Normally, lasers are employed to record the diffraction pattern of an object, from which a 3-dimensional image of the object can be rebuilt.

In Pribram's opinion 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. This crossing of the brain provides the interpretation of the sensory perception in the form of a "memory wave", which in turn crosses the brain. The various waves that travel through the brain can interfere. The interference of a memory wave and a perceptual (e.g., visual) wave generates a structure that resembles an hologram.

Pribram employs Fourier transformations to deal with the dualism between spacetime and spectrum, and Gabor's phase space to embed spacetime and spectrum. All perceptions (and not only colors or sounds) can be analyzed into their component frequencies of oscillation and therefore treated by Fourier analysis. Dirac's "least action principle" (which favors the least expenditure of energy) constrains trajectories in such a space. Gabor's uncertainty principle sets a limit at which both frequency and spacetime can be concurrently determined (the fundamental minimum is Gabor's "quantum of information"). Structure and process are two aspects of the same entity, distinguished only by the scale of observation (from a distance an entity looks like a structure, but close enough it is a process).

In Pribram's theory, therefore, the formalism of Quantum Theory applies to the modeling of brain functions themselves (brain microprocesses and physical microprocesses can be described by the same formalism). Incidentally, Pribram suggested that consciousness may occur primarily in dendritic-dendritic processing and that axonal firings may support primarily automatic, non-conscious activities.

Quantum brain dynamics

The Heisenberg and Von Neumann tradition has always viewed the brain as a "quantum measuring device". But the Japanese physicist Kunio Yasue, the American physicist Gordon Globus and others, claims that brain substrates uphold second-order quantum fields, which cannot be treated as mere measuring devices.

Yasue, building on the quantum field theory developed in the 1960s by the Japanese physicist Hiroomi Umezawa and on his concept of "corticons" as more primitive than "neurons", has developed a "quantum neurophysics" that explains how the classical world can originate from quantum processes in the brain.

Yasue is not a connectionist. The fact that neurons are organized inside the brain is of negligible importance in his theory.

Yasue thinks that several layers of the brain can host quantum processes, whose quantum properties explain consciousness and cognition. Yasue presents the brain as a macroscopic quantum system. He focuses on water megamolecules in the space between neurons, which can combine to form extended quantum systems, interacting with the neural networks.He focuses on the sensory system, whose quantum field causes some special molecules in the membrane of the neuron to undergo Froehlich condensation and cause, in turn, macroscopic coherence.

He focuses on structures such as microtubules which lie inside the neuron, and which contain quasi-crystalline water molecules that again lend themselves to quantum effects. The function of this quantum field could be cognitive: some particular quantum states could record memory.

He focuses on a bioplasma of charged particles which interact with the electromagnetic field, an ideal vehicle for a merge of the sensory quantum field with the memory quantum field, an ideal vehicle for the creation of classical reality. Thus, classical order can continually unfold in this bioplasma.

According to traditional interpretations of Quantum Theory, classical order unfolds because of a measurement and the consequent collapse of the wave function. According to Globus, classical order unfolds from the interaction between quantum cognition (the memory quantum field, or "holoworld") and quantum reality (the sensory quantum field).

Heisenberg's discontinuous sequence of collapsed realities is replaced by a continuous unfolding of worlds from a holoworld.

Yasue shows how consciousness could arise from the interaction between the electromagnetic field and molecular fields of water and protein. Furthermore, Yasue maintains that the evolution of the neural wave function is not random, as would result from the traditional quantum theories, but optimized under a principle of "least neural action". Random effects of consciousness are replaced by a "cybernetic" consciousness which is more in the tradition of the self as a free-willing agent.

Quantum-gravitational Consciousness

One of the strongest proponents of a theory of consciousness founded on Quantum Theory is Roger Penrose in person, one of the leading British physicists of our times. In his opinion, consciousness must be a quantum phenomenon because neurons are too big to account for consciousness. Inside neurons there is a "cytoskeleton", the structure that holds cells together, whose "microtubules" (hollow protein cylinders 25-nanometers in diameter) control the function of synapses. Penrose believes that consciousness is a manifestation of the quantum cytoskeletal state and its interplay between quantum and classical levels of activity.

The theory exposed by Penrose and his close American associate Stuart Hameroff is very detailed. The story begins with Penrose's distinction between "subjective" and "objective" reduction. Subjective reduction is what happens when an observer measures a quantity in a quantum system: the system is not in any specific state (the system is in a "superposition" of possible states) until it is observed, the observation causes the system to reduce (or "collapse") to a specific state. This is the only reduction known to traditional Quantum Theory. Objective reduction is a Penrose discovery, part of his attempt at unifying Relativity Theory and Quantum Theory.

Superpositioned states each have their own space-time geometry. Under special circumstances, which microtubules are suitable for, the separation of space-time geometry of the superpositioned states (i.e., the "warping" of these space-times) reaches a point (the quantum gravity threshold) where the system must choose one state. The system must then spontaneously and abruptly collapse to that one state. So, objective reduction is a type of collapse of the wave function which occurs when the universe must choose between significantly differing spacetime geometries.

This "self-collapse" results in particular "conformational states" that regulate neural processes. These conformational states can interact with neighboring states to represent, propagate and process information. Each self-collapse corresponds to a discrete conscious event. Sequences of events then give rise to a "stream" of consciousness. The proteins somehow "tune" the objective reduction which is thus self-organized, or "orchestrated".

In concluding, the quantum phenomenon of objective reduction controls the operation of the brain through its effects on coherent flows inside microtubules of the cytoskeleton.

In general, the collapse of the wave function is what gives the laws of nature a non-algorithmic element. Otherwise we would simply be machines and we would have no consciousness.

Therefore, Penrose and Hameroff believe that "protoconscious" information is encoded in space-time geometry at the fundamental Planck scale and that a self-organizing Planck-scale process results in consciousness. This means that Penrose believes in a Platonic scenario of conscious states that exist in a world of their own, and to which our minds have access; except that his "world of ideas" is a physicist's world: quantum spin networks encode proto-conscious states and different configurations of quantum spin geometry represent varieties of conscious experience. Access to these states (or consciousness as we know it) originates when a self-organizing process (the objective reduction) somehow coupled with neural activity collapses quantum wave functions at Planck-scale geometry.

There is a separate mental world, but it is grounded in the physical world

A Physics of Consciousness

Now that legions of physicists are delving into the topic, physical models of consciousness abound.

One has to do with other dimensions. The unification theories that attempt at unifying General Relativity (i.e. gravitation) and Quantum Theory (i.e., the weak, electrical and strong forces) typically add new dimensions to the four ones we experience. These dimensions differ from space in that they are bound (actually, rolled up in tiny tubes) and in that they only exist for changes to occur in particle properties. Saul-Paul Sirag's hyperspace, for example, contains many physical dimensions and many mental dimensions (time is one of the dimensions they have in common).

The physicist Erich Harth is trying to explain consciousness by means of a process that relies on "positive" feedback. Feedback can be negative or positive. Negative feedback is the familiar one, which has to do with stabilizing a process, in particular its input with its output. Positive feedback works in the opposite direction, at the edge of instability: the signal is amplified by itself, weakening the relationship between input and output. Harth thinks that a loop of positive feedback spreads through different areas of the brain and provides "selective amplification. If that be the case, then unification of consciousness would occur at the bottom of the sensory pyramid, not at the top.

The American physicist Alwyn Scott applies Eigen's model of "hypercycles" to consciousness. He makes consciousness stem from a procedure which is analogous to the one that generates life: simple cells originate complex cells which originate hypercomplex cells.

A critique of Neuroscience

All contemporary Neuroscience is based on classical Physics. No surprise that it derives a view of the brain as a set of mechanical laws: that is the "only" view that classical Physics can derive. No surprise that it cannot explain how consciousness arises, since there is no consciousness in classical Physics: it was erased from the study of matter by Descartes' dualism (that mind and matter are separate), on which foundations Newton erected classical Physics (the science of matter, which does not deal with mind). By definition, Descartes' dualism predicts that mind cannot be explain from matter, and Newton's Physics is an expression of dualism. Which means that dualism predicts that Newton's Physics cannot explain mind. Neuroscientists who are looking for consciousness miss that simple syllogism: they are looking for consciousness using a tool that is labeled "this tool does not deal with consciousness".

Contemporary Neuroscience rests on the idea that a physical system is made of independent parts which interact only with their immediate neighbords and whose behavior over time is deterministic. This is the principle behind all computational models of the brain.

Within this paradigm, a mind is the product of a brain, which is one particular system of the many that populate the universe.

This is a very interesting paradigm, but it is not what Physics prescribes today. It is what Physics prescribed a century ago, before it was showed to be wrong.

The New Materialism

A contemporary American philosopher of the mind, David Chalmers, argues that consciousness cannot be explained with a reductionist approach, because it does not belong to the realm of matter. Chalmers proposes to expand Science in a fashion that is still compatible with today's Science (in the areas where it is successful) and that allows for a dualist approach.

Chalmers distinguishes between a phenomenal concept of mind (the way it feels) and a psychological concept of mind (what it does). Every mental property is either a phenomenal property, a psychological one or a combination of the two. The mind-body problem is therefore made of two parts, one that deals with the mental faculties and one that deals with how/why those mental faculties also give rise to awareness of them (Jackendoff's "mind-mind problem"). Pain, for example, is both a material entity that can be analyzed functionally, in terms of its effect on behavior, and the feeling of pain. The same distinction applies to consciousness, with psychological consciousness being commonly referred to as "awareness"; but phenomenal consciousness always comes with psychological consciousness. Awareness is having access to information that may affect behavior.

Chalmers' brand of monism admits both physical and non-physical features in the world. His dualism is different from Descartes' in that it claims that "consciousness is a feature of the world" which is somehow related to its physical properties. A new, fundamental, irreducible feature (a set of "protophenomenal" properties) must be added to space-time, mass, charge, spin, etc., and a set of "psychophysical" laws (explaining how phenomenal properties depend on physical properties) must be added to the laws of nature. Chalmers outlines a few candidate psychophysical laws, such as the principle of coherence between consciousness and cognition and the principle of organizational invariance. The former states a tight relationship between the structure of consciousness and functional organization. The latter states that every system organized in the appropriate way will experience the same conscious states, regardless of what substance it is made of, i.e., consciousness is "organizationally invariant". From these principles, it follows that consciousness is due to the functional organization of the brain. It also follows that anything having the proper functional organization can have consciousness, regardless of the material it is made of.

Still looking for fundamental laws of consciousness, Charmers offers an interpretation of his theory based on the dualism between information and pattern: information is what pattern is from the inside. Consciousness is information about the pattern of the self. Information becomes therefore the link between the physical and the conscious. Ultimately, everything in the universe may be conscious, at least to some degree.

A Darwinist Theory of Consciousness

If we assume that a similar law of evolution is responsible for all living phenomena, from the creation of species to the immune system, and we admit that mind is one of them, then a possible scenario emerges, which is compatible with the latest neurophysiological findings.

Thoughts are continuously and randomly generated, just like the immune system generates antibodies all the time without really knowing which ones will be useful. Thoughts survive for a while, giving rise to minds that compete for control of the brain. At each time, one mind prevails because it can better cope with the situation.

Which mind prevails has an influence on which thoughts will be generated in the future. In practice, a mind is the mental equivalent of a phylogenetic thread (of a branch of the tree of life).

We are conscious, by definition, only of the mind that is prevailing.

In ancient times the minds generared chaotically were simply shouted to the "rational" apparatus of the brain, which would act as the mediator with the environment: it would translate "hallucinations" into actions. and the result of actions into emotions, and emotions would either reinforce or weaken the mind in control. Emotions would select the mind.

This is more evident in children, which explore many unrelated thoughts in a few minutes: whatever the various minds produce. Later, the adult is better adjusted to select "minds" and does not need to try them all out. The adult has been "biased" by natural selection to recognize the "best" minds.

The 40 Hz radiation may simply be a way of scanning all available thoughts and of reporting emotions back to all minds (in other words, of reading the outputs of the minds, in the form of thoughts, and of feeding them new inputs, in the form of emotions).

A Materialistic Theory of Consciousness

But "what" is consciousness? What substance is it made of?

Many attempts have been made at explaining consciousness by reducing it to something else. To no avail. There is no way that our sensations can be explained in terms of particles. So, how does consciousness arise in matter? Maybe it doesn't arise, it is always there.

I am conviced that, no matter how detailed an account is provided of the neural processes that led to an action (say, a smile), that account will never explain where the feeling associated to that action (say, happiness) came from. No theory of the brain can explain why and how consciousness happens, if it assumes that consciousness is somehow created by some neural entity which is completely different in structure, function and behavior from our feelings.

From a logical standpoint, the only way out of this dead-end is to accept that consciousness must be a physical property.

When we try to explain consciousness by reducing it to electrochemical processes, we put ourselves in a situation similar to a scientist who decided to explain electrical phenomena by using gravity. Electrical phenomena can be explained only if we assume that electricity comes from a fundamental property of matter (i.e. from a property that is present in all matter starting from the most fundamental constituents) and that, under special circumstances, enables a particular configuration of matter to exhibit "electricity".

Similarly, if consciousness comes from a fundamental property of matter (from a property that is present in all matter starting from the most fundamental constituents), then, and only then, we can study why and how, under special circumstances, that property enables a particular configuration of matter (e.g., the brain) to exhibit "consciousness".

Any paradigm that tries to manufacture consciousness out of something else is doomed to failure. Things don't just happen. Ex nihilo nihil fit. Consciousness doesn't come simply from the act of putting neurons together. It doesn't appear like magic. Conductivity seems to appear by magic in some configurations of matter (e.g. metallic objects), but there's no magic: just a fundamental property of matter, the electrical charge, which is present in every single particle of this universe, a property which is mostly useless but that under the proper circumstances yields the phenomenon known as conductivity.

Particles are not conductors by themselves, just like they are not conscious, and most things made of particles (wood, plastic, glass, etc. etc.) are not conductors (and maybe have no consciousness), but each single particle in the universe has an electrical charge and each single particle in the universe has a property, say, C. That property C is the one that allows our brain to be conscious. I am not claiming that each single particle is conscious or that each single piece of matter in the universe is conscious. I am only arguing that each single particle has this property C which, under the special circumstances of our brain configuration (and maybe other brain configurations as well and maybe even things with no brain) yields consciousness.

Just like electricity and gravitation are macroscopic properties that are caused by microscopic properties of the constituents, so consciousness may be a macroscopic property of our brain that is caused by a microscopic property of its constituents. Just like electrical phenomena can only be reduced to smaller-scale electrical phenomena (all the way to the charge of each single constituent), so consciousness can only be reduced to smaller-scale conscious phenomena.

Any theory that tries to manufacture consciousness from other properties of matter is doomed. Even Penrose's, because he too makes consciousness appear by magic out of unconscious matter (molecules that are unconscious suddenly acquire consciousness when organized in a cytoskeleton).

My theory is not dualistic and is not materialistic. Like dualists, I admit the existence of consciousness as separate from the physical properties of matter as we know them; but at the same time, like materialists, I consider consciousness as arising from a physical property (that we have not discovered yet) that behaves in a fundamentally different way from the other physical properties. So in a sense it is not a "physical" property, but it is still a property of all matter. Mine is an identity theory, in that I think that mental correspond to neural states, but it goes beyond identity because I also think that the property yielding consciousness is common to all matter, whether it performs neural activity or not.

What made Descartes believe in dualism is the unity of consciousness. But electrical conductors also exhibit a unity of electricity, and still electrical phenomena can be reduced to a physical property of matter

The main problem is the lack of an empirical test for consciousness. We cannot know whether a being is conscious or not. We cannot "measure" its consciousness. We cannot rule out that every object in the universe, including each elementary particle, has consciousness: we just cannot detect it. Even when I accept that other human beings are conscious a) I base my assumption on similarity of behavior, not on an actual "observation" of their consciousness; and b) I somehow sense that some people (poets and philosophers, for example) may be more conscious than other people (lawyers and doctors, for example).

The trouble is that our mind is capable only of observing conscious phenomena at its own level and within itself. Our mind is capable of observing only one conscious phenomenon: itself.

A good way to start is to analyze why consciousness is limited to the brain. Why does consciousness apply only to the brain? What is special about the brain that cannot be found anywhere else? If the brain is made of common matter, of well-known constituents, what is it that turns that matter conscious when it is configured as a brain, but not when it is configured as a foot? And why does it stop being conscious if oxygen or blood are not supplied?