Reality  for most of us consists of the table and chair; of people and pets; of the sun and the moon. It could also include such insubstantial items as pleasure and plain, freedom and bondage, justice and oppression.  In short, ordinarily, the word  Reality  refers to what we see and hear, touch, smell and feel.

     As a first approximation, this is also what one means in Physics by the term Reality. But more importantly, for the physicist Reality  refers to aspects of the world that exist inde­pendently of whether and how human beings recognize or perceive them. This  hard-core view of Reality  guided and served physics  well during the past four centuries. It is not intrinsically different from the common-sense notion of Reality.

     However, this view has undergone significant modifications as a result of the emergence of Relativity Theory  and Quantum Physics  during the first third of our cen­tury. Other developments in fundamental physics during more recent decades have brought about even further changes in our usual ideas about Reality.

     In this paper I  will discuss the some of the  concepts  of Reality  that emerges from a study of Physics, both classical and modern.

A Definition of Reality

     We  witness Reality  in its multiple variety. As the poet Shelley wrote,

          Day and night, aloof, from the high towers

          And terraces, The Earth and Ocean seem

          To sleep in one another’s arms, and dream

          Of Waves, flowers, clouds, woods, rocks, and all that we

          Read in their smiles, and call reality.

     But one may  wonder whether  such an aspect exists independently of the human mind. This is not a trivial  metaphysical question, because one cannot be absolutely certain that one’s current experience is  any more substantial than a dream. After all, while dreaming one entertains the feeling that  the associated experiences are as real as in the waking state. 

     Then again, our channels of perception are not always totally reliable. The two  horizontal lines below which are intercepted by slanting lines, are in fact straight and parallel to each other. Yet they strike us as being curved.

     We are all familiar with  other optical illusions like  the rising and setting of the sun, and mirages. There are also other types of illusions involving hearing, touching, smelling, and tasting.

     One goal of physics is to seek the truth behind the appearances. What makes the sky blue and the stars twinkle, why do diamonds sparkle and magnets attract? Exploring such questions is the equivalent of de-robing Nature, for the physical world is quite different when we view it in its stark nudity. The exploration into the  nature of things  has also proved to be extremely fruitful, for the more we know about Nature's  inner workings and behavior patterns, the more we are able to predict her future course and cajole her to our advantage. This is one of the primary reasons why physics is studied in our universities.

     Anything  we call Reality   is of interest in the context of  discourse only in so far as such an item has been recognized, directly or indirectly, by a human Mind, and can be communicated. Therefore, one valid definition could be that Reality is  some aspect of the world which has been recognized by the human Mind. But, as  with optical illusions,  not everything that is formulated in or by the human Mind may have existence independently of it. We therefore put the further stipulation that an element of Reality  must have an existence independently of the human Mind.

     This assumption is at the basis of the classical Cartesian-Newtonian Physics which reigned supreme for three hundred years.

Human experience and its modes

     No matter what Reality  is, its recognition is an essentially a cerebral-sensory  process. In other words, the recognition of Reality in whatever aspect is an intensely human experience. Now,  human experiences involve interactions with the external world of things and living entities. Interactions occur in different (though intermingling) modes. The principal modes through which we interact with the world around are  emotional,  sensory,   spiritual, and  intellectual. Thus, love and compassion, as also anger and hatred, are of the emotional kind.* The sensory mode includes those resulting directly from our channels of perceptions, causing  pleasure and pain. The spiritual mode involves religious communion, cultural participation, and the like. The intellectual mode calls for the use of the logical  and analytical faculties of the human mind. 

     These different modes of experience cannot be separated out  in water tight compartments. Thus, for example, aesthetic (spiritual) experience  may be combined with the sensory (seeing); laughter  (emotional) with the humor (intellectual), and so on. An important consequence of this impossibility of separation of the different experiential  modes is that  conflicts  can and do arise between various modes. Such conflicts have generated numerous heated debates, mounds of writing, scholarly and otherwise, as well as downright violence.

Intellectual Mode: Goal of Science/Physics

     Physics, like most sciences,  is a primarily an intellectual mode of interaction with the world. Therefore, for Physics  Reality  is what emerges from  an intellectual analysis of human sense perceptions. This implies the following:

     (a) The logical process  is essential in determining if something is part of Reality or not.  In other words, there can be no scientific  acceptance  of Reality  if reason and logic are relegated to the background.

     (b) There must be consistency  in the framework. Consistency  means that logically incompatible elements will not be simultaneously accepted as valid.

     (c) The mathematical dimension  of the world is brought into play in the physicist’s recognition of Reality.  This is because mathematics is the most sophisticated expression of the  logical mode.

Perceived Reality and Sense perceptions

     As Immanual Kant pointed out long ago, even at the ordinary level, when we recognize and analyze the world,  we cannot avoid the intermediate filters of  human sensory perceptions and cerebral modes.   As a result, what we perceive as part of the real world  is only a mapping on the human sensory system of whatever the thing-in-itself  may be. Thus, if our optical apparatus had evolved without an ability to generate colors, the world would appear to us as on the screen of a black and white TV.

     Indeed, our world  of experience would be drastically different if the scope and sensitivity of our perceptive faculties underwent significant changes. For example:

     If our ears were sensitive to very low frequency pressure-waves, we could hear the breathing of our neighbors.

     If our eyes were sensitive to infra-red waves, we would recognize people and things as radiating sources.

     If our eyes could detect the gases we inhale and exhale, we could feel quite uncomfortable seeing how the the same airs freely enter in and out of the mouths and nostrils and the people in a room.

     If our skins were sensitive to the impact of individual microcosmic entities, we would experience perpetual pin-pricks from the zillions of oxygen and nitrogen molecules that keep bouncing off our bodies all the time.

     Physics has brought to our awareness these and other aspects of the world from which we have been shielded perhaps because, as T. S. Eliot said,

        Human kind cannot bear very much reality.

     But physics has also revealed the subtle aspects of Reality  underlying the blue of the sky and the fury of the volcano, and explained why lightning precedes thunder, why foot balls follow parabolic paths, and a thousand other matters.

Physics and Objectivity

     The major  goal of physics (and of science more generally) is to acquire objective knowledge about the physical world: by which is meant, an understanding of Reality  that is independent of the human factor. One of the fundamental insights of the classical scientific world-view  is that the physical universe has existed for eons before the emergence of the human mind, and will continue  for another stretch of time even after the whiff of human presence fades away without a trace from the grand expanse of space. Understandably, the cosmos  displays cold and utter indifference to our presence and activities in it.

     Now, since a knowledge of the cosmos is possible only in the context of human awareness, a universe devoid of the human Mind would be supremely inconsequential and irrelevant to us, as it is to the myriad other creatures inhabiting the planet. In other words, a not-always recognized fact about scientific knowledge is that, for all its objectivity, it is intensely anthropocentric.

Impact of quantum physics

     In the framework of pre-twentieth century physics,  Physical Reality  has an external, objective existence. Space, time, matter and energy are the four corner-stones of that physics. Their existence is completely independent of the telescope, the microscope and the inquiring Mind. Phenomena  function in accordance with well-defined laws whether human beings have detected them or not. In other words, there is an external objective Reality  which the  completely detached observer studies, interprets, understands,  manipulates, etc. This  basic credo of  classical physics  is still operationally accepted by most practicing physicists.      

     But the physics of the twentieth century seems to suggest that this common-sense-inspired  classical version of Reality  may not be entirely correct. In fact, the classical view is based on the rarely articulated assumption, and evolutionarily generated conviction,  that there is a little ego inside each of us which does all the observing,  thinking and calculating; for it is based on a clear-cut dichotomy between an observing and analyzing principle on the one hand and the totally unaffected observed entity on the other. Unfortunately, physics has not probed into what the observing ego is with as much care and attention as it has devoted to the exploration of the external world. That neglect is not unlike looking through a telescope without checking if  the lenses are clean and transparent. What appears as a magnificent line in the sky could be a mere crack on the eye-piece.

     Indeed, a major revelation of twentieth century physics is that the distinction  between the observer and the observed, between the knower and the known, which is implicit in all scientific investigations, dissolves at the microcosmic level. When we penetrate into the ultimate core of matter and energy, the boundaries between  subject and  object become fuzzy, just as when we move farther and farther away from a cluster of dots, the whole thing looks like one big hazy smear. It is as if  at the fundamental level there seems to be an  intermingling of mind and matter.

     Though the public at large and a good section of practicing scientists are untouched by its implications, this dissolution of the subject-object dichotomy has momentous impacts on our appraisal  of the world. It undermines our long accepted notions of an external world independent of the human Mind. The erasing of the observer-observed distinction intrudes on the independence of the state of the system that is being studied, throwing all objectivity to the winds.

Consciousness physics

     Another  major revelation of quantum physics is even more intriguing: A small group of  physicists have been trying in recent years to draw consciousness into the realm of physics. A rather abstract result of quantum physics (the so-called Bell 's theorem) and certain rather puzzling experimental results (relating to what are known as polarization reversals in electrons and photons) lead to the classically unacceptable notions of non-locality  and interconnectedness.

     Non-locality  implies that what happens in one region of space could be affected by something in a totally (spatio-temporally) unconnected region. If this were so, such outrageous things as events happening without a cause, or effects preceding a causes,  would be possible. Such possibilities can be avoided only if it is assumed that it is possible to transmit information instantaneously. But this is anathema to  the current foundations of physics. Thus quantum physics has led us to a rather serious philosophical quagmire.

     Interconnectedness  means that in some inscrutable way, every entity in the universe is intrinsically intertwined with every other entity, a sort of cosmic network made up of inseparable parts. Interconnectedness  is a radically new idea, altogether alien to the Cartesian-Newtonian scheme of things in which  entities have separate and independent existence; and between which connections may be established only through specific interactions.

     This means that ultimately the building blocks of the physical world do not conform to the model of classical physics according to which they can be specified as occupying well-defined points of space at well-defined instants of time, and as mutually interacting through processes that can never travel faster than light. This reductionist framework will have to give way to a holistic view if we are to grasp the intricacies of the world through the intellectual mode.

     Physicists who are  cultured in and committed to the classical tradition of  science have difficulty erasing the subject-object demarcations and the associated  definitions of Reality   from their world-view on the basis of  the newly emerging paradigm which tends to give  more than conventional credence to  meditative insights and mystical claims.  Yet, when the carefully performed experiments pertaining to the so-called Bell 's inequality are analyzed and interpreted in the framework  of the enormously successful framework of quantum physics, one cannot afford to ignore these visions of Reality  except by conceding that it is beyond the capacities of human Mind to build any self-consistent model of Reality. This is precisely some of the founders of quantum physics conceded.

Order and Meaning out of Chaos

     What is created in our consciousness as external Reality  may have just about as much objectivity as episodes on a TV screen: entertaining and emotionally jolting perhaps, hilarious or tear-jerking as the case may be, but in truth only very rapidly  varying photonic dots of uneven intensities. The deeper we probe into the ultimate nature of the world, the more we are forced to revise our familiar view of Reality.

     Classical physics already revealed that at the molecular level there is more randomness than order. It is not impossible to derive mathematically the observed  precise mathematical laws from basic disorder. This was in fact one of the impressive achievements of classical statistical mechanics. But consciousness recognizes  more than symmetry and pattern; it also discerns meaning and  experience. To explain these  from atomic and molecular configurations is a very different matter. Meaningful totality arising from meaningless microcosmic processes  leave us puzzled at the intellectual level. Somehow, analysis is unable to solve the mystery of holistic coherence. There is more to sentences than  combinations of letters with occasional spaces strewn in between.

Cerebral biochemistry

     Our sensory system is essentially a function of the properties of a neural network which arises from the (electro-chemical) properties of the molecules in  normal human brains. If  alien molecules are injected into the brain,  or if the usual  chemicals are modified in some way (as through meditation, chanting, etc.), deviations of  Reality  result from the normal modes. Depending on one's point of view, these deviations are described either euphemistically as higher visions, or disparagingly  as hallucinations, when in fact they merely reflect unusual activations of the cerebral-neural network.

     Experimenters like Aldous Huxley and  Timothy Leary  have vouched that small doses of certain chemicals  provide the equivalent of cosmic revelations such as have been reported only by mystics.  They  have concluded from their experiences that there are  loftier dimensions of Reality  which are accessible to those who would allow potent substances to help open the closed doors of perception. 

     These claims show that what we perceive as  Reality   is to a large extent a function of the biochemical molecules that come into play in our brains. We all share a Reality only in so far as, and only for so long as, we have similar chemicals powering our cerebral circuitry. If the world view of other creatures is very different from our own,  this has little to do with  higher dimensions of Reality. The simple fact is that they are sporting with a different bunch of chemical substances.

Personal Reality

     Since the intellect plays a major role at the discursive level, it tends to accept  as Reality  only those elements that conform to its criteria. However, the other interaction moes generate other levels of Reality as well which the intellect is unable to accept as such. This causes of conflicts between science and other modes.

     For example, we speak of love being real, of a feeling of elation being real, of friendship being real, etc. But these  Realities  are  different from the table being real in the following  important respects:

     1. The Reality  of love, friendship, etc. is far more intensely personal than that of a table, and may not be subject to universal agreement by a community of normal human brains, whereas this will be the case with the table. So is the Reality  of the uniqueness or superiority of one's own religous tradition or beliefs.

     2. A precise formulation of Reality  of the first kind may or may not be of common interest in communal interactions, whereas the contrary is the case with realities of the second kind.

     3. As a consequence, Realities of the first kind are far more significant and relevant to the individual   whereas those of the second kind are of  greater interest to a group  or community.

     4. It is not possible to subject  Realities  of the first kind to quantitative analysis.

     The first  kind of Reality  may therefore be described as individually subjective.

     The second kind of Reality is sometimes called objective reality. More appropriately, it should be called collectively subjective. It is this collectively subjective Reality  that constitutes established scientific reality.

Virtual and Higher Dimensional Realities

     One of the least expected, and most remarkable impacts on the physicist’s notion of Reality  is from developments in computer science. It is well-known that with the aid of computers we can simulate Reality. The TV games which have invaded popular culture do precisely this.      

     More sophisticated versions of such games have led to such incredibly close mimic of actual experiences that this prompts us to define a new kind of Reality, the so-called Virtual Reality. Virtual Reality  has practically all the characteristics of Reality in terms of sensory experiences, except that, like funny money, it is all fake, and we don't have to report it in our tax returns. This raises the question from which we started: How do we know that what our own taxed Reality  is no more than some other type of Virtual Reality?

     Than again, TV Reality is a two dimensional projection whereas our more familiar Reality is in three dimensional space. It could well be that there are still  higher dimensional Realities  which are beyond the perception or conception of our cerebral systems which are condemned to a three-dimensional mode. Could it be that higher dimensional intelligences, endowed with loftier levels of perception are populating multidimensional worlds whence they are watching our doings, even as we study and comment upon termites and E-coli?

     There is no way we can prove or disprove such a possibility, but it is as good a thought as any to make some concluding comments.

Concluding Thoughts: Orders of Reality

     The ironic conclusion to which scientific inquiries have led us is that our hope of  discovering  the ultimate nature of Reality  is as exciting and reachable as trying to stand right under the rainbow, for anything that strikes us as Reality  is but a sophisticated mapping of something outside of the brain. And this should be true of the brain also. The curious phenomenon of the brain examining and talking about itself is not without some inherent awkwardness, like attempts at writing  an objective autobiography. 

     One way of not getting lost in this maze of Realities is by introducing the notion of Orders of Reality.  Thus, we may define First Order Reality  as what we directly observe and experience. Second order Reality  consists of the fundamental entities and causes of First Order Reality.  Physics informs us of this Second Order Reality. But these entities and causes such as they are recognized are functions of our own sensors and analyzers. Therefore, we may imagine a Third Order Reality of which Second Order Reality  is only a reflection. It may well be that there are Fourth and still Higher Order Realities which are for ever beyond even our conceptual perception. At the other end, we may consider a Zeroth Order Reality   consisting of the pure creations of the human Mind which are powerful factors in human culture and interaction. All our mythology and poetry,  fiction and even some history, and other creations of the human imagination, as well such abstract elements as justice and equality, freedom and honor, belong to Zeroth Order Reality.    

Suggestions for further reading

E. A. Abbot, Flatland  (Dover, N.Y., 1952).

D. Bohm, Causality and chance in modern physics (Temple U Press, Philadelphia, 1957).

D. Bohm, Wholeness and the implicate order  (Routledge Kegan, London, 1980).

R. Harris, The nature of reality (McGraw Hill , N.Y., 1987).

W. Heisenberg, The physicist's conception of nature  (Greenwood Press Westport 1970).

A. I. Miller, Imagery in scientific thought  (Birkhäuser Boston,1984).

P. Watzlawick, How real is real? , (Vintage N.Y., 1977).

A. Comfort, Reality and empathy,   (SUNY, Albany, 1984).

P. Davies, God and the new physics, (Simon and Schuster, 1984).

I. Prigogine and I. Strengers, Order out of chaos (Heinemann, London, 1984).

*Some may describe these as psychological, but the particular description is irrelevant for our present discussion.