Farewell to Reality (2 page)

The contrasting approaches of Einstein and Hawking are particularly relevant to the aims of this book. Hawking is a rather indulgent fairytale physicist, recently declaring that a form of untried and untested (and possibly untestable) superstring theory is the unified theory that Einstein spent the latter part of his life searching for.

Einstein, in contrast, was a theoretical physicist of the old school. His many pronouncements on the aims of science and the methods that scientists use are broadly consistent with common conception among both the majority of scientists and the wider public. On the basis of these pronouncements I suspect he would have been quite shocked by the state of contemporary theoretical physics. I had initially thought to title this book
What Would Einstein Say?
but have settled for trying to convey his likely sense of outrage by identifying for each chapter relevant quotations from his extraordinary lexicon.

I am no longer a professional scientist, and some might argue that this means I am no longer qualified to hold an opinion on this subject. Obviously, I don't agree. I believe I have studied it long and hard enough to allow me not only to form and hold an opinion but also to express it as best I can.

But make no mistake, what you have in this book is an opinion that is very
personal.
Consequently, when I acknowledge a debt of gratitude to Professors Steve Blundell at Oxford University, Helge Kragh at Aarhus University in Denmark and Peter Woit at Columbia University in New York, who read and commented on the draft manuscript, I want to be absolutely clear that this acknowledgement should not suggest that they accept all my arguments. Of course, I take full responsibility for any errors or misconceptions that remain.

Jim Baggott

July 2012

^*
And, to my mind at least, produced for an audience of 12 year olds suffering from attention deficit disorder. Or maybe I'm just getting too old and cranky? Answers on a postcard please …

^*
With acknowledgement to Piers Bizony.

^*
This quote appears in Richard Feynman,
The Character of Physical Law
, (MIT Press, Cambridge, MA, 1965), p. 129

^*
And yes, I'm also interested in the income-stream.

^**
My daughter, shortly to start her second year as a university drama student, was sitting dutifully in the audience. She thought about Brooks' question and challenged herself to name three scientists. Before Brooks could continue, she had identified Einstein, Hawking and Cox.

1

The Supreme Task

Reality, Truth and the Scientific Method

The supreme task of the physicist is to arrive at those universal elementary laws from which the cosmos can be built up by pure deduction. There is no logical path to these laws; only intuition, resting on sympathetic understanding of experience, can reach them.

Albert Einstein
¹

Now I want to be absolutely clear and unequivocal upfront. I trained as a scientist, and although I no longer practise, I continue to believe — deeply and sincerely — that only science, correctly applied, can provide a sure path to true knowledge of the real world. If you want to know what the world is made of, where it came from, how it works and how it came to be as it is today, then my recommendation is to look to science for the answers.

I hope I speak with conviction, but be assured that I am not a zealot. I will happily admit that the practice of science is not always black and white. We are forced to admit shades of grey. It is a lot looser and more ambiguous than many practitioners are themselves often willing to admit. Much of the looseness and ambiguity arises because science is after all a human endeavour, and human beings are complicated and unpredictable things.

But it would be a mistake to think that the humanity of scientists is responsible for all the vagueness, that everything would be crystal clear if only a few flaky individuals would stick to the rules. When we look closely, we discover that what passes for the ‘rules' of scientific endeavour are themselves rather vague and open to interpretation. This, I will argue, is how fairy-tale physics manages to thrive.

Our problems begin as soon as we try to unpack the sentences that I used to open this introductory chapter. Reality is at heart a metaphysical concept — it is, quite simply, ‘beyond physics' and therefore beyond science. And just what, exactly, is this thing we call ‘science'? For that matter, how should we define ‘truth'?

That's a lot of difficult questions. And, it seems, if I'm going to accuse a bunch of theoretical physicists of abandoning the scientific method and so betraying the search for scientific truth about the nature of physical reality, then I'll need properly to ground this assertion in some definitions. It's better to try to clear all this up before we really get going.

There's quite a lot at stake here, so I've summarized my main conclusions about reality, science and truth in a series of six ‘principles', handily picked out in italics with a grey background so that you can easily refer back to them if needed. Collectively, these principles define what it is that we apply science to, what science is and how we think we know when it is ‘true'.

Of course, many physicists and philosophers of science will disagree with these principles, with varying degrees of vehemence. This, I think, is rather the point. What's important is how they seem to
you.

In Part I, my mission will be to tell the story of the authorized version of reality in the context of these statements, showing how science has been applied to generate this contemporary version of the truth. This section concludes with a chapter summarizing most (but not all) of the problems with this authorized version and gives the reasons why we know it can't be the whole truth.

In Part II, I will attempt to explain how contemporary theoretical physics seeks to address these problems. It is here that fairy-tale physics sneaks in through unavoidable loopholes in our interpretation of one or more of the principles, but fails to satisfy all of them taken together. It is on this basis that I will seek to reject fairy-tale physics as metaphysics.

Let's start with reality.

Real is simply electrical signals interpreted by your brain

‘What is real?' asked the character Morpheus in the 1999 Hollywood blockbuster movie
The Matrix.
‘How do you define real? If you're talking about what you can feel, what you can smell, what you can
taste and see, then real is simply electrical signals interpreted by your brain.'
²

These days we tend not to look for profundity in a Hollywood movie,
^*
but it's worth pausing for a moment to reflect on this observation. I want to persuade you that reality is like liquid mercury: no matter how hard you try, you can never nail it down. I propose to explain why this is by reference to three ‘everyday' things: a red rose, a bat and a dark cave.

So, imagine a red rose, lying on an expanse of pure white silk. We might regard the rose as a thing of beauty, its redness stark against the silk sheen of brilliant nothingness. What, then, creates this vision, this evocative image, this tantalizing reality? More specifically, what in reality creates this wonderful experience of the colour red?

That's easy. We google ‘red rose pigment' and discover that roses are red because their petals contain a subtle mixture of chemicals called anthocyanins, their colour enhanced if grown in soil of modest acidity. So, anthocyanins in the rose petals interact with sunlight, absorbing certain wavelengths of the light and reflecting predominantly red light into our eyes. We look at the petals and we see red. This all seems quite straightforward.

But hang on. What, precisely, is ‘red light'? Our instinct might be to give a scientific answer. Red light is electromagnetic radiation with wavelengths between about 620 and 750 billionths of a metre. It sits at the long-wavelength end of the visible spectrum, sandwiched between invisible infrared and orange.

But light is, well, light. It consists of tiny particles of energy which we call photons. And no matter how hard we look, we will not find an inherent property of ‘redness' in photons with this range of wavelengths. Aside from differences in wavelength, there is nothing in the physical properties of photons to distinguish red from green or any other colour.

We can keep going. We can trace the chemical and physical changes that result from the interactions of photons with cone cells in your retina all the way to the stimulation of your visual cortex at the back of your brain. Look all you like, but you will not find the
experience
of the colour red in any of this chemistry and physics. It is obviously only
when you synthesize the information being processed by your visual cortex in your
conscious mind
that you experience the sensation of a beautiful red rose. And this is the point that Morpheus was making.

We could invent some equivalent scenarios for all of our other human senses — taste, smell, touch and hearing. But we would come to much the same conclusion. What you take to be your reality is just electrical signals interpreted by your brain.

What is it like to be a bat?

Now, you might be ready to dismiss all this as just so much juvenile philosophizing. Of course we're all reliant on the way our minds process the information delivered to us by our senses. But does it make any sense at all for the human mind to have evolved processes that represent reality differently from how it really is? Surely what we experience and the way we experience it
must
correspond to whatever it is that's ‘out there' in reality? Otherwise how could we survive?

To answer these questions, it helps to imagine what it might be like to be a bat.

What does the world look like — what passes for reality — from a bat's point of view? We know that bats compensate for their poor night vision by using sophisticated sonar, or echolocation. Bats emit high-frequency sounds, most of them way above the threshold of human perception. These sound waves bounce off objects around them, forming echoes which they then detect.

Human beings do not use echolocation to gather information about the world. We cannot possibly imagine what it's like for a bat to be a bat because we lack the bat's sensory apparatus, in much the same way that we cannot begin to describe colours to someone who has been blind from birth.

But the bat is a highly evolved mammal, successful in its own ecological niche. Just because I can't understand what reality might be like for a bat doesn't mean that the bat's perceptions and experiences of that reality are any less legitimate than mine.

What this suggests is that evolutionary selection pressures lead to the development of a sensory apparatus that delivers a finely tuned
representation
of reality. All that matters is that this is a representation
that lends a creature survival advantages. There is no evolutionary selection pressure to develop a mind to represent reality as it really is.

Plato's allegory of the cave

So, what do we perceive if not reality as it really is? In
The Republic,
the ancient Greek philosopher Plato used an allegory to describe the situation we find ourselves in. This is his famous allegory of the cave.

Imagine you are a prisoner in a dark cave. You have been a prisoner all your life, shackled to a wall. You have never experienced the world outside the cave. You have never seen sunlight. In fact, you have no knowledge of a world outside your immediate environment and are not even aware that you are a prisoner, or that you are being held in a cave.

It is dark in the cave, but you can nevertheless see men and women passing along the wall in front of you, carrying all sorts of vessels, and statues and figures of animals. Some are talking. As far as you are concerned, the cave and the men and women you can see constitute your reality. This is all you have ever known.

Unknown to you, however, there is a fire constantly burning at the back of the cave, filling it with a dim light. The men and women you can see against the wall are in fact merely shadows cast by real people passing in front of the fire. The world you perceive is a world of crude appearances of objects which you have mistaken for the objects themselves.

Plato's allegory was intended to show that whilst our reality is derived from ‘things-in-themselves' — the real people that walk in front of the fire — we can only ever perceive ‘things-as-they-appear' — the shadows they cast on the cave wall. We can never perceive reality for what it is; we can only ever perceive the shadows.
‘Esse est percipi',
declared the eighteenth-century Irish philosopher George Berkeley: essence is perception, or to be is to be perceived.

These kinds of arguments appear to link our ability to gain knowledge of our external reality firmly with the workings of the human mind. A disconnect arises because of the apparent unbridgeable distance between the physical world of things and the ways in which our perception of this shapes our mental world of thoughts, images and ideas. This disconnect may arise because we lack a rigorous
understanding of how the mind works. But knowing how the mind works wouldn't change the simple fact that thoughts are very different from things.

Veiled reality

It doesn't end here. Another disconnect, of a very different kind but no less profound, is that between the quantum world of atomic and subatomic dimensions and the classical world of everyday experience. What we will discover is that our anxiety over the relationship between reality and perception is extended to that between reality and measurement.

Irrespective of what thoughts we think and how we think them, we find that we can no longer assume that what we
measure
necessarily reflects reality as it really is. We discover that there is also a difference between ‘things-in-themselves' and ‘things-as-they-are-measured'.