The Nature of Reality

What is reality

What is Reality ?

We humans have a problem with reality. We experience it all the time, but struggle to define it, let alone understand it. We don’t know when it began, how big it is, where  it came from or where it is going, and we certainly don’t know why it exists.

In this classic New Scientist article, reproduced in our new Essential Guide: The Nature  of Reality, physicist Roger Penrose explains how modern physics suggests that what  we perceive and what exists may be two very different things – an intriguing mystery  at the intersection of physics, mathematics and our conscious experience.

What do we understand by “reality”?   For those of us who consider ourselves  hard-headed realists, there is a kind of  common-sense answer: “Reality  consists of those things – tables,   chairs, trees, houses, planets, animals,  people and so on – which are actual things made of  matter”. We might tend to include some more abstract seeming notions such as space and time, and the  totality of all such “real” things would be referred to as “the universe”.

Some might well consider that this is not the whole of reality, however. In particular, there is the question  of the reality of our minds. Should we not include a  conscious experience as something real? And what  about concepts such as truth, virtue or beauty? Of  course, some hard-headed people might adopt a  doggedly materialist point of view and take mentality and all its attributes to be secondary to what is  materially real. Our mental states, after all (so it would  be argued), are simply emergent features of the  construction and behaviour of our physical brains.   We behave in certain ways merely because our brains  act according to physical laws – the same laws as those  that are strictly obeyed by all other pieces of physical  material. Conscious mental experience, accordingly, has no further reality than that of the material  underlying its existence; though not yet properly  understood, it is merely an “epiphenomenon”, having  no additional influence on the way that our bodies  behave beyond what those physical laws demand.

Some philosophers might take an almost opposite view, arguing that it is conscious experience itself that  is primary. From this perspective, the “external reality”  that appears to constitute the ambient environment  of this experience is to be understood as a secondary construct that is abstracted from conscious sense-data. Some might even feel driven to the view that one’s own particular conscious experience is to be regarded  as primary, and that the experiences of others are  themselves merely things to be abstracted, ultimately,  from one’s own sense-data.

I have considerable difficulty with such a picture  of reality, which seems to me lopsided. At best, it  would be difficult to convince anyone else of a theory of reality that depended upon such solipsism for its  basis. Moreover, I find it extremely hard to see how the  extraordinary precision that we seem to observe in the  workings of the natural world should find its basis in  the musings of any individual.

Even if such a solipsistic basis is not adopted, so that  the totality of all conscious experience is to be taken as the primary reality, I still have great difficulty.  This would seem to demand that “external reality”  is merely something that emerges from some kind of majority-wins voting amongst the individual  conscious experiences of all of us taken together. 

I cannot see that such an emergent picture could  have anything like the robustness and precision that  we seem to see outside ourselves, stretching away  seemingly endlessly in all directions in space and in  time, and inwards to minute levels that we do not  directly perceive with our senses; all requiring many  different kinds of precision instruments to.

The Nature of Reality

explore the universe over a vast range of different  scales. True, there is a mystery about consciousness  itself, and it is profoundly puzzling how it could come  about from the seemingly purely calculational,  unfeeling and utterly impersonal laws of physics that  appear to govern the behaviour of all material things.  Nevertheless, among the basic laws of physics that we  know – and we do not yet know all of them – some are  precise to an extraordinary degree, far beyond the  precision of our direct sensory experiences, or of the  combined calculational powers of all conscious  individuals within the ken of mankind.

One example of an over-reachingly deep and  precise physical theory is Einstein’s magnificent  general theory of relativity, which improves even  upon the already amazingly accurate Newtonian  theory of gravity. In the behaviour of the solar system,  Newton’s theory is precise to something like one part  in 107: Einstein’s theory does much more, giving not  only corrections to Newton’s theory that become  relevant when gravitational fields get large, but also  predicting completely new effects, such as black holes,  gravitational lensing and gravitational waves – the  analogues, for gravitation, of the light waves of Maxwell’s electromagnetic theory.

The agreement between theory and experiment  here has been extraordinary. Astronomers have,  for example, been monitoring the orbits of one  double neutron star system – known as PSR 1913+16 –  since the 1970s. The emission of Einstein’s predicted  gravitational waves from this system has been  confirmed, and there was agreement between the  signals received from space and the overall predictions  of Einstein’s theory to an astonishing 14 decimal places,  even before the LIGO collaboration first directly  detected a passing gravitational wave in 2015. At  the other end of the size scale, there are multitudes  of very precise observations that give innumerable  confirmations of the accuracy of quantum theory  and also of its generalisation to the quantum theory  of relativistic fields, which gives us quantum  electrodynamics, one of the underpinnings of the  standard model of particle physics. The magnetic  moment of an electron, for example, has been  precisely measured to some 12 decimal places, and  the observed figures are matched precisely by the  theoretical predictions of quantum electrodynamics.

An important point to be made about these physical  theories is that they are not just enormously precise  but depend upon mathematics of very considerable  sophistication. It would be a mistake to think of the  role of mathematics in basic physical theory as being  simply organisational, where the entities that  constitute the world just behave in one way or another,  and our theories represent merely our attempts –  sometimes very successful – to make some kind of  sense of what is going on around us. In such a view  there would be no particular mathematical order to  the world; it would be we who, in a sense, impose  this order by describing, in an elaborate mathematical  scheme, those aspects of the world’s behaviour that  we can make sense of.
To me, such a description again falls far short of  explaining the extraordinary precision in the.

“ What substance does  the ‘reality’ around us  actually have?”
agreement between the most remarkable of the  physical theories that we have come across and  the behaviour of our material universe at its most  fundamental levels. Take the example of gravitation  again. Newton’s beautifully simple mathematical  description was later found to remain accurate to a  degree tens of thousands of times greater than the  observational precision available in the 17th century  when he formulated it. Newton had needed to  introduce the procedures of calculus in order to  formulate his theory. 

In the 20th century, Einstein  added the sophistication of differential geometry –  and increased the agreement between theory and  observation by a factor of around 10 million. In each  case, the increased accuracy was not the result of a new  theory being introduced only to make sense of vast  amounts of new data. The extra precision was seen  only after each theory had been produced, revealing  accord between physical behaviour at its deepest level  and a beautiful, sophisticated mathematical scheme.

Mathematics all the way down

If, as this suggests, the mathematics is indeed there in  the behaviour of physical things and not merely  imposed by us, then we must ask again what substance  does this “reality” that we see about us actually have?  What, after all, is the real table that I am now sitting at  actually composed of? It is made of wood, yes, but what  is wood made of? Well, fibres that were once living cells.  And these? Molecules that are composed of individual  atoms. And the atoms? They have their nuclei, built  from protons and neutrons and glued together by  strong nuclear forces; these nuclei are orbited by  electrons, held in by the considerably weaker  electromagnetic forces. G
deeper, protons and  neutrons are to be thought of as composed of more  elementary ingredients, quarks, held together by  further entities called gluons. Just what are electrons,  quarks and so on, though? The best we can do at this  stage is simply to refer to the mathematical equations  that they satisfy, which for electrons and quarks  would be the Dirac equation. What distinguishes a  quark from an electron would be their very different  masses and the fact that quarks indulge in interactions  – namely the “strong” interactions – that electrons are  blind to. What, then, are gluons? They are “gauge”  particles that mediate the strong force – which is again  a notion that can only be understood in terms of the  mathematics used to describe them.

Even if we accept that an electron, say, should be  understood as being merely an entity that is the  solution of some mathematical equation, how do we  distinguish that electron from some other electron?  Here a fundamental principle of quantum mechanics  comes to our rescue. It asserts that all electrons are  indistinguishable from one another: we cannot talk of  this electron and that electron, but only of the system,  which consists of a pair of electrons, say, or a triple or a  quadruple, and so on. Something very similar applies  to quarks or gluons or to any other specific kind of  particle. Quantum reality is strange that way.

Indeed, quantum reality is strange in many ways.

Many quantum theorists   would say we should abandon   any notion of reality

Individual quantum particles can, at one time, be in  two different places – or three, or four, or spread out  throughout some region, perhaps wiggling around  like a wave. Indeed, the “reality” that quantum theory  seems to be telling us to believe in is so far removed  from what we are used to that many quantum theorists  would tell us to abandon the very notion of reality  when considering phenomena at the scale of particles,  atoms or even molecules.

This seems rather hard to take, especially when we  are also told that quantum behaviour rules all  phenomena, and that even large-scale objects, being  built from quantum ingredients, are themselves  subject to the same quantum rules. Where does  quantum non-reality leave off and the physical reality  that we actually seem to experience begin to take over?  Present-day quantum theory has no satisfactory  answer to this question. My own viewpoint concerning  this – and there are many other viewpoints – is that  present-day quantum theory is not quite right, and that  as the objects under consideration get more massive  then the principles of Einstein’s general relativity begin  to clash with those of quantum mechanics, and a  notion of reality that is more in accordance with our  experiences will begin to emerge. The reader should be  warned, however: quantum mechanics as it stands has  no accepted observational evidence against it, and all  such modifications remain speculative. Moreover,  even general relativity, involving as it does the idea   of a curved space-time, itself diverges from the notions  of reality we are used to.

Whether we look at the universe at the quantum  scale or across the vast distances over which the effects  of general relativity become clear, then, the commonsense reality of chairs, tables and other material things  would seem to dissolve away, to be replaced by a deeper  reality inhabiting the world of mathematics. Our  mathematical models of physical reality are far from  complete, but they provide us with schemes that  model reality with great precision – a precision  enormously exceeding that of any description that  is free of mathematics. There seems every reason to  believe that these already remarkable schemes will be  improved upon and that even more elegant and   subtle pieces of mathematics will be found to mirror  reality with even greater precision. Might  mathematical entities inhabit their own world, the  abstract Platonic world of mathematical forms? It is an  idea that many mathematicians are comfortable with.  In this scheme, the truths that mathematicians seek  are, in a clear sense, already “there”, and mathematical  research can be compared with archaeology; the  mathematicians’ job is to seek out these truths as a   task of discovery rather than one of invention. To a  mathematical Platonist, it is not so absurd to seek an  ultimate home for physical reality within Plato’s world.

This is not acceptable to everyone. Many  philosophers, and others, would argue that  mathematics consists merely of idealised mental  concepts, and, if the world of mathematics is to be  regarded as arising ultimately from our minds, then we  have reached a circularity: our minds arise from the  functioning of our physical brains, and the very precise  physical laws that underlie that functioning are.

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