Many regard consciousness as the final frontier of science. Although science has produced a great deal of knowledge about the brain and the nervous system, it did not (yet) produce a viable theory of consciousness.

• There is the seemingly intractable problem that consciousness cannot be measured, detected, or quantified in any way.
• To further complicate things, consciousness is about inner (first-person) experience and its subjective qualities, whereas science relies on ideas and experiences that can be observed and verified by third parties.

The investigation of inner phenomena involves subjective, idiothetic accounts, whereas the investigation of outer phenomena involves objective, verifiable accounts. It would seem that the scientific method, which relies on repeatable experiments to test a hypothesis, reaches its limits when dealing with consciousness. One must therefore ask whether science is able to explain consciousness at all.

Scientists have responded to these problems in two ways.

One group claims that consciousness is not a scientific concept to begin with, that its is too vague, and that claims involving consciousness are unverifiable.

• This position was taken to the extreme by the 20th century behaviourist movement, which simply ignores consciousness.
• It tends to see the mind as a hypothetical construct, disregarding internal states entirely, only considering external states (behaviour).

The other group of scientists acknowledges the existence of internal conscious states and claims that these can be fully explained by neuroscience.

• There is a variety of such views, known as materialism, reductionism, functionalism, and biological naturalism.
• Some proponents of these views assert that consciousness is a “bag of tricks” (Dennett) and that - by and large - it has already been explained by neuroscience.

But perhaps this is jumping to conclusions. Science postulates a materialist understanding of consciousness, but there are significant gaps in this understanding.

The materialist view occasionally appears like that of the mythical tribesman who discovered a TV set.

• Although ignorant of the existence of radio waves, he is confident that he understands the origin of the voices and images in the TV.
• After he has carefully disassembled the TV, he is able to demonstrate that applying a voltage to certain points produces an audible noise in the speaker, or a dot of light on the screen.
• He has even worked out how the electron beam can be modulated to create a matrix of dots.
• On account of these discoveries, he triumphantly declares that the voices and pictures are produced inside the electronic circuits of the TV set and that the operating principle of the TV set can be explained without invoking “supernatural” radio waves.

Yet, his fellow tribesmen are not quite satisfied with this explanation.

• It seems too mechanical to them and they keep wondering why the voices and images in the TV set appear so real.
• The tribal scientist justifies himself: “We have not worked out all the details yet, but we understand the principle.”

This situation is perhaps analogous to present day consciousness research.

Mainstream scientists and philosophers believe that consciousness is based on and produced by the brain.

• This might be compared to the idea that TV images and sounds are produced inside the TV set.
• Obviously, in case of the TV set, it is only half the truth.
• The TV images and sounds are neither local to the TV set, nor do they have a life of their own.
• They are produced elsewhere and transmitted by radio waves.
• We all know that a TVs have an antenna and a receiver that pick up radio waves and translate them into voltages to generate images and sounds.

What if the brain and nervous system relate to consciousness like the TV set to radio signals?

• Let's call this the nonlocal model of consciousness.

If we accept the nonlocal model of consciousness provisionally, we can compare TV reception to sense perception.

• We can compare qualia (conscious experience) to TV images and sounds; we can compare memories to the recording function, thoughts to the playback and edit functions, and mental chatter to audiovisual noise.
• Furthermore, if the nervous system/brain functions as receiver/modulator of consciousness rather than its producer, it follows that consciousness is not based on the brain, but that the brain is based on consciousness.

There are a number of theoretical considerations and phenomena that point in this direction.

• These phenomena show the limits of the current mainstream (materialistic) understanding of consciousness and provide theoretical support for the nonlocal model of consciousness.

In the remainder of this section, we will look at five such points:

1. the epistemic gap in materialism,
2. the absence of a neural correlate of consciousness,
3. out-of-body experiences (OBEs),
4. near-death experiences (NDEs), and
5. the measurement problem in quantum physics.

The epistemic gap, also known was the explanatory gap, is the gaping hole in materialist ontology.

• It is the failure to explain how something immaterial, such as conscious experience, arises from something material, such as the brain.

The epistemic gap can also be phrased as follows:

• How does subjective experience arise from electrochemical processes in the brain?
• Subjective experience - or qualia - seems to be entirely nonphysical.
• No scientist has managed to explain how qualia arise and why they arise.
• After all, we can perfectly well imagine an organism responding to external signals and stimuli without being conscious of them.

Materialism offers two different approaches to deal with the “problem” of mind: reductionism and emergentism.

• Reductionism argues that it is principally possible to reduce higher-order systems to lower-order systems.
• It postulates that mind is a higher-order system that can be reduced - in principle - to the biological system of the human brain and body.
• The biological system can in turn be reduced to chemistry, which can again be reduced to physics.
• Therefore - according to reductionism - mind is ultimately physical.

The problem with this approach is that reductionism cannot point out the causal relationships involved in each step of the reduction. On this account, reductionism fails.

The non-reductionist approach - known as emergentism - holds that the higher-order system emerges from the lower-order system on account of supervenience. The concept of supervenience is defined as follows:

• A set of properties A is said to supervene upon another set B if no two things can differ with respect to A-properties without also differing with respect to their B-properties.
• In other words, any difference in the higher-order system implies a difference in the lower-order system.
• It is said that mind supervenes on the biological system and that mind displays new emergent properties which are not intrinsic to the underlying system.

Upon closer inspection, we find that emergentism suffers from the same problem as reductionism.

• It fails to account for the causal relationships between higher and lower order systems.
• Supervenience cannot explain why properties are related as they appear.
• Hence, invoking supervenience is a bit like appealing to magic. It is not an explanation at all.
• This strongly suggests that the epistemic gap cannot be bridged by materialism.

The French philosopher René Descartes held that the soul was located in the pineal gland and that consciousness emanates from it.

• This is often cited as the first attempt to relate consciousness to a biological structure.
• While the study of the brain can be traced back to ancient Egypt, modern neuroscience began in the latter half of the 20th century.
• Since then, neuroscientific research has produced a massive amount of data and knowledge about the brain which is still growing at a fascinating pace.

One of the goals of neuroscience is to correlate mental states with biophysical states, systems and processes in the brain. This effort has only partly been successful. For example,

• We can correlate the capacity of speech to the Wernicke and Broca areas.
• We can correlate motor action to the motor cortex,
• Vision to the optical nerve and the visual cortex,
• Certain feelings such as arousal, pleasure, and excitement to neurotransmitters.

However, the search for the neural correlate of consciousness has come up empty.

• Decades of research did not produce what was originally envisioned by neuroscientists – the correlate or substrate of phenomenal consciousness.

At the beginning of the 21st century, conscious experience remains as enigmatic as ever.

• This is not to say that it eludes neuroscience completely.
• Many epiphenomena of conscious experience - from brainwaves and brain chemistry to neural activity - have been explored and can be matched to certain types of experience.

Yet, it is phenomenal experience itself that puzzles scientists.

• There is no causal explanation that leads from brain states to qualia.
• There are no neural correlates for thought, beliefs, and ideas.
• In fact, most neuroscientists have given up the search for the neural correlate of conscious experience. They feel that it is the wrong approach.
• The absence of a neural correlate suggests that consciousness does not originate or reside in the brain at all.

Out-of-body experiences (OBEs) are ostensibly based on the separation of consciousness from the body.

• Those who experience an OBE report that they see their own body from the outside, that they float through space, and that they can penetrate solid objects.
• With a prevalence of 5%-10%, OBEs are more common than generally believed.

Although an OBE often occurs spontaneously, or as a consequence of body trauma, it can also be self-induced.

• Experienced out-of-body travellers can prolong the experience and travel at will.

There are two theories about it:

• One says that there is something that leaves the body;
• The other says nothing leaves the body and that OBEs are complex hallucinations caused by non-ordinary brain states.

Both theories are problematic, because the first relies on the paranormal concept of an “astral body”, and the second theory cannot account for the complexity of the experience and its veridical aspects.

There are many reports of so-called veridical OBEs. These involve correct accounts of remote objects, events, or people which are later verified by a third person.

• For example, the subject might report about people in another room, or things that are outside the field of vision and cannot possibly be perceived through the sense organs.

Several veridical OBEs have occurred under laboratory conditions.

• Dr. Michael Sabom reported 32 cases of cardiac arrest patients who were able to describe their resuscitation in great detail.
• Dr. Pim van Lommel and Dr. Kenneth Ring have published similar studies with well over 100 cases of veridical OBEs.
• Dr. Charles Tart has conducted an experiment where the subject has correctly identified a 5-digit number that was placed on top of a shelf - invisible to the subject- after an OBE.

Mainstream science cannot explain these findings.

• Veridical OBEs can be explained if we assume that consciousness is nonlocal to the brain.

Near-death experiences (NDEs) are reported by 10%-15% of all people who find themselves in a life-threatening situation due to critical surgery, cardiac arrest, an accident, or some other cause.

• Since most of these people end up in a hospital, the conditions for scientific study are favourable.

The first case studies were published by E. Kübler-Ross, R. Moody et al in the 1970s.

• Since then a large amount of reports and studies with thousands of cases have been collected, more recently by B. Greyson, M. Morse, S. Parnia, P.V. Lommel and others.

NDEs are conscious experiences at impending death that have recognisable features, such as a sense of well-being, love, and peace, movement through a tunnel or a passage, a bright spiritual light, meeting deceased relatives and friends and/or spiritual beings.

• The most astounding observation is that consciousness continues after clinical death.
• Recent studies have shown that these experiences can occur even when neuronal activity in the brain has ceased, so that - according to neuroscience - there should not be any conscious experience at all.

Sceptics argue that NDEs are caused by physiological processes in the dying brain.

• For example, they hold that the experience of a tunnel and bright light is caused by the loss of cell function in the visual system due to anoxia (lack of oxygen).
• However, while every patient with cardiac arrest experiences anoxia, not everyone experiences a NDE and not every NDE features a tunnel experience, which questions the causal connection.

Other sceptics argue that the experience is caused by the release of dimethyltryptamine (DMT) or endorphines in the brain.

• Again, DMT release does not necessarily result in a NDE.
• DMT is also released at night time during sleep, though in smaller quantities, and it does not have the life-changing effect that NDEs are known for.
• Furthermore, if NDEs were a drug-induced, one would expect the experience to have personal random contents, much like a dream or an LSD trip.
• Reports of congenitally blind people who were suddenly able to experience vision in a NDE make biological explanations even harder.

So far, there is no coherent physiological explanation for the NDE phenomenon.

Dr. Pim Van Lommel writes in his paper About The Continuity Of Our Consciousness:

According to our concept, grounded on the reported aspects of consciousness experienced during cardiac arrest, we can conclude that our consciousness could be based on fields of information, consisting of waves, and that it originates in the phase-space.

… Such understanding fundamentally changes one’s opinion about death, because of the almost unavoidable conclusion that at the time of physical death consciousness will continue to be experienced in another dimension, in an invisible and immaterial world, the phase-space, in which all past, present and future is enclosed. Research on NDE cannot give us the irrefutable scientific proof of this conclusion, because people with a NDE did not quite die, but they all were very, very close to death, without a functioning brain.

In short, the measurement problem in quantum mechanics is the problem how and why Schrödinger's wave function collapses upon measurement.

• The word “collapse” describes a transition from a superposition of different states of a particle, as described by Schrödinger's wave function, to a single state upon interaction.

The measurement of physical quantum system always results in a definite state, whereas the wave function describes the evolution of the same system as a multitude of superposed states, each with a certain probability.

• In abstract terms, the wave function collapse describes the reduction of a system of potentialities to a single definite state.

Since it is impossible to observe the collapse directly, a number of different interpretations exist.

• These interpretations revolve around several key questions, namely how nature behaves at the subatomic level, whether nature is deterministic or non-deterministic, and whether the observer plays a causal role in the wave function collapse.

The Copenhagen interpretation is one of the more popular interpretations of the measurement problem.

• It was first formulated by Heisenberg and Bohr in the 1920s, and it became later synonymous with indeterminism and Bohr's correspondence principle.

Today, there are several variations of this interpretation.

• Since it asserts collapse upon measurement, one particular version of the Copenhagen interpretation posits that collapse is caused by a conscious observer, which implies that consciousness plays a participatory role in the measurement.
• Hence, it is called the Participatory Anthropic Principle (PAP), following J.A. Wheeler's Anthropic Principle.

While PAP is considered speculative, many scientists feel that the classical paradigm of a separate observer can be questioned and that the role of consciousness needs to be reevaluated in view of quantum mechanics.

• The idea of consciousness interacting non-locally with physical systems could therefore be an important element in understanding how reality works at the subatomic level.