No More Learning

This little bit chipped off in brilliance
And went whizzing through the slow, vast, succulent stems.
I believe there were no flowers then.
In the world where the humming-bird flashed ahead of creation.
I believe he pierced the slow vegetable veins with his long beak. Probably he was big
As mosses, and little lizards, they say, were once big.
Probably he was a jabbing, terrifying monster.
We look at him through the wrong end of the telescope of Time, Luckily for us. Unrhyming Poems, 1928
D. H. Lawrence's poem about hummingbirds is almost wholly inaccurate and therefore, superficially, unscientific. Yet, in spite of this, it is a passable shot at how a poet might take inspiration from geological time. Lawrence lacked only a couple of tutorials in evolution and taxonomy to
bring his poem within the pale of accuracy, and it would be no less arresting and thought-provoking as a poem. After another tutorial Lawrence, the miner's son, might have turned fresh eyes on his coal fire, whose glowing energy last saw the light of day - was the light of day - when it warmed the Carboniferous tree ferns, to be laid down in earth's dark cellar and sealed for three million centuries. A larger obstacle would have been Lawrence's hostility to what he wrongly thought of as the anti- poetic spirit of science and scientists, as when he grumbled that
Knowledge has killed the sun, making it a ball of gas with spots . . . The world of reason and science . . . this is the dry and sterile world the abstracted mind inhabits.
I am almost reluctant to admit that my favourite of all poets is that confused Irish mystic William Butler Yeats. In old age Yeats sought a theme and sought for it in vain, finally returning, in desperation, to enumerate old themes of his young manhood. How sad to give up, wrecked among heathen dreams, marooned amid the faeries and fey Irishry of his affected youth when, an hour's drive from Yeats's tower, Ireland housed the largest astronomical telescope then built. This was the 72-inch reflector, built before Yeats was born by William Parsons, third earl of Rosse, at Birr Castle (where it has now been restored by the seventh earl). What might a single glance at the Milky Way through the eyepiece of the 'Leviathan of Parsonstown' not have done for the frustrated poet who, as a young man, had written these unforgettable lines?
Be you still, be you still, trembling heart; Remember the wisdom out of the old days:
Him who trembles before the flame and the flood, And the winds that blow through the starry ways, Let the starry winds and the flame and the flood Cover over and hide, for he has no part
With the lonely, majestical multitude.
from The Wind Among the Reeds (1899)
Those would make fine last words for a scientist, as would, now that I think about it, the poet's own epitaph, 'Cast a cold eye/On life, on death. / Horseman, pass by! '
But, like Blake, Yeats was no lover of science, dismissing it (absurdly), as the 'opium of the suburbs', and calling us to 'Move upon Newton's town. ' That is sad, and the kind of thing that drives me to write my books.
Keats, too, complained that Newton had destroyed the poetry of the rainbow by explaining it. By more general implication, science is poetry's
killjoy, dry and cold, cheerless, overbearing and lacking in everything that a young Romantic might desire. To proclaim the opposite is one purpose of this book, and I shall here limit myself to the untestable speculation that Keats, like Yeats, might have been an even better poet if he had gone to science for some of his inspiration.
It has been pointed out that Keats's medical education may have equipped him to recognize the mortal symptoms of his own tuberculosis, as when he ominously diagnosed his own arterial blood. Science, for him, would not have been the bringer of good news, so it is less wonder if he found solace in an antiseptic world of classical myth, losing himself among panpipes and naiads, nymphs and dryads, just as Yeats was to do among their Celtic counterparts. Irresistible as I find both poets, forgive my wondering whether the Greeks would have recognized their legends in Keats, or the Celts theirs in Yeats. Were these great poets as well served as they could have been by their sources of inspiration? Did prejudice against reason weigh down the wings of poesy?
It is my thesis that the spirit of wonder which led Blake to Christian mysticism, Keats to Arcadian myth and Yeats to Fenians and fairies, is the very same spirit that moves great scientists; a spirit which, if fed back to poets in scientific guise, might inspire still greater poetry. In support, I adduce the less elevated genre of science fiction. Jules Verne, H. G. Wells, Olaf Stapledon, Robert Heinlein, Isaac Asimov, Arthur C. Clarke, Ray Bradbury and others have used prose-poetry to evoke the romance of scientific themes, in some cases explicitly linking them to the myths of antiquity. The best of science fiction seems to me an important literary form in its own right, snobbishly underrated by some scholars of literature. More than one reputable scientist has been introduced to what I am calling the spirit of wonder through an early fascination with science fiction.
At the lower end of the science fiction market the same spirit has been abused for more sinister ends, but the bridge to mystical and romantic poetry can still be discerned. At least one major religion, Scientology, was founded by a science fiction writer, L. Ron Hubbard (whose entry in the Oxford Dictionary of Quotations reads, 'If you really want to make a million . . . the quickest way is to start your own religion'). The now dead adherents of the cult of 'Heaven's Gate' probably never knew that the phrase appears twice in Shakespeare and twice in Keats, but they knew all about Star Trek and were obsessed with it. The language of their website is a preposterous caricature of misunderstood science, laced with bad romantic poetry.
The cult of The X-Files has been defended as harmless because it is, after all, only fiction. On the face of it, that is a fair defence. But regularly
recurring fiction - soap operas, cop series find the like - are legitimately criticized if, week after week, they systematically present a one-sided view of the world. The X-Files is a television series in which, every week, two FBI agents face a mystery. One of the two, Scully, favours a rational, scientific explanation; the other agent, Mulder, goes for an explanation which either is supernatural or, at very least, glorifies the inexplicable. The problem with The X-Files is that routinely, relentlessly, the supernatural explanation, or at least the Mulder end of the spectrum, usually turns out to be the answer. I'm told that, in recent episodes, even the sceptical agent Scully is starting to have her confidence shaken, and no wonder. But isn't it just harmless fiction, then? No, I think the defence rings hollow. Imagine a television series in which two police officers solve a crime each week. Every week there is one black suspect and one white suspect. One of the two detectives is always biased towards the black suspect, the other biased towards the white. And, week after week, the black suspect turns out to have done it. So, what's wrong with that? After all, it's only fiction! Shocking as it is, I believe the analogy to be a completely fair one. I am not saying that supernaturalist propaganda is as dangerous or unpleasant as racist propaganda. But The X-Files systematically purveys an anti-rational view of the world which, by virtue of its recurrent persistence, is insidious.
Another bastard form of science fiction converges upon Tolkienian faked- up myth. Physicists rub shoulders with wizards, interplanetary aliens escort princesses sidesaddle on unicorns, thousand-port-holed space stations loom out of the same mist as medieval castles with ravens (or even pterodactyls) wheeling around their gothic turrets. True, or calculatedly modified, science is replaced by magic, which is the easy way out.
Good science fiction has no dealings with fairytale magic spells, but is premised on the world as an orderly place. There is mystery, but the universe is not frivolous nor light-fingered in its changeability. If you put a brick on a table it stays there unless something moves it, even if you have forgotten it is there. Poltergeists and sprites don't intervene and
hurl it about for reasons of mischief or caprice. Science fiction may
tinker with the laws of nature, advisedly and preferably one law at a time, but it cannot abolish lawfulness itself and remain good science fiction. Fictional computers may become consciously malevolent or even, in Douglas Adams's masterly science comedies, paranoid; spaceships may warp-drive themselves to distant galaxies using some postulated future technology, but the decencies of science are essentially maintained. Science allows mystery but not magic, strangeness beyond wild
imagining but no spells or witchery, no cheap and easy miracles. Bad science fiction loses its grip on moderated lawfulness and substitutes the 'anything goes' profligacy of magic. The worst of bad science fiction joins
hands with the 'paranormal', that other lazy, misbegotten child of the sense of wonder which ought to be motivating true science. The popularity of this kind of pseudo-science at least seems to suggest that the sense of wonder is widespread and heartfelt, however misapplied it may be. Here lies the only consolation I can find in the pre-millennial media obsession with the paranormal; with the immensely successful X- Files and with popular television shows in which routine conjuring tricks are misrepresented as violating natural law.
But let us return to Auden's pleasing compliment and our inversion of it. Why do some scientists feel like shabby curates among literary dukes, and why do many in our society perceive them so?
Undergraduates specializing in science at my own university have occasionally remarked to me (wistfully, for peer pressure in their cohort is strong) that their subject is not seen as 'cool'. This was illustrated for me by a smart young journalist whom I met on a recent BBC television discussion series. She seemed almost intrigued to meet a scientist, for she confided that when at Oxford she had never known any. Her circle had regarded them from a distance as 'grey men', especially pitying their habit of getting out of bed before lunch. Of all absurd excesses, they attended 9 a. m. lectures and then worked through the morning in the labs. That great humanist and humanitarian statesman Jawaharlal Nehru, as befits the first prime minister of a country that cannot afford to mess about, had a more realistic view of science.
It is science alone that can solve the problems of hunger and poverty, of insanitation and illiteracy, of superstition and deadening custom and tradition, of vast resources running to waste, or a rich country inhabited by starving people . . . Who indeed could afford to ignore science today? At every turn we have to seek its aid . . . The future belongs to science and those who make friends with science*.
(1962)
Nevertheless, the confidence with which scientists sometimes state how much we know and how useful science can be, may spill over into arrogance. The distinguished embryologist Lewis Wolpert once admitted that science is occasionally arrogant, and he went on to remark, mildly, that science has a certain amount to be arrogant about. Peter Medawar, Carl Sagan and Peter Atkins have all said something similar.
* Correcting copy in August 1998, I cannot let this pass without sadly reflecting that Nehru would feel India's decision to carry out nuclear tests, unilaterally and in defiance of world opinion, to be a shocking abuse of science and a desecration of his memory and that of Mahatma Gandhi.
Arrogant or not, we at least pay lip-service to the idea that science advances by disproof of its hypotheses. Konrad Lorenz, father of ethology, characteristically exaggerated when he said he looked forward to disproving at least one pet hypothesis daily, before breakfast. But it is true that scientists, more than, say, lawyers, doctors or politicians, gain prestige among their peers by publicly admitting their mistakes. One of the formative experiences of my Oxford undergraduate years occurred when a visiting lecturer from America presented evidence that conclusively disproved the pet theory of a deeply respected elder statesman of our zoology department, the theory that we had all been brought up on. At the end of the lecture, the old man rose, strode to the front of the hall, shook the American warmly by the hand and declared,
in ringing emotional tones, 'My dear fellow, I wish to thank you. I have been wrong these fifteen years. ' We clapped our hands red. Is any other profession so generous towards its admitted mistakes?
Science progresses by correcting its mistakes, and makes no secret of what it still does not understand. Yet the opposite is widely perceived. Bernard Levin, when a columnist on The Times of London, sporadically published tirades against science, and on 11 October 1996 he wrote one headed 'God, me and Dr Dawkins', with the subtitle 'Scientists don't know and nor do I - but at least I know I don't know', above which was a cartoon of me as Michelangelo's Adam encountering the pointing finger of God. But as any scientist would vigorously protest, it is of the essence of science to know what we do not know. This is precisely what drives us to find out. In an earlier column, of 29 July 1994, Bernard Levin had made light of the idea of quarks ('The quarks are coming! The quarks are coming! Run for your lives . . . '). After further cracks about 'noble science' having given us mobile telephones, collapsible umbrellas and multi- striped toothpaste, he broke into mock seriousness:
Can you eat quarks? Can you spread them on your bed when the cold weather comes?
This sort of thing doesn't really deserve a reply, but the Cambridge metallurgist Sir Alan Cottrell gave it two sentences, in a Letter to the Editor a few days later.
Sir: Mr Bernard Levin asks 'Can you eat quarks? ' I estimate that he eats 500, 000,000, 000,000, 000,000, 000,001 quarks a day . . . Yours faithfully. . .
Admitting what you don't know is a virtue, but gloating ignorance of the arts on such a scale would, quite rightly, not be tolerated by any editor. Philistine ignorance of science is still, in some quarters, thought witty
and clever. How else to explain the following little joke, by a recent editor of the London Daily Telegraph? The paper was reporting the dumbfounding fact that a third of the British population still believes that the sun goes round the earth. At this point the editor inserted a note in square brackets: '[Doesn't it? Ed. ]' If a survey had shown a third of the British populace believing that Shakespeare wrote The Iliad, no editor would humorously feign ignorance of Homer. But it is socially acceptable to boast ignorance of science and proudly claim incompetence in mathematics. I have made the point often enough to sound plaintive, so let me quote Melvyn Bragg, one of the most justly respected commentators on the arts in Britain, from his book about scientists, On Giants' Shoulders (1998).
There are still those who are affected enough to say they know nothing about the sciences as if this somehow makes them superior. What it makes them is rather silly, and it puts them at the fag end of that tired old British tradition of intellectual snobbery which considers all knowledge, especially science, as 'trade'.
Sir Peter Medawar, that swashbuckling Nobel Prize-winner whom I've already cited, said something similar about 'trade', vividly lampooning the British distaste for all things practical.
It is said that in ancient China the mandarins allowed their fingernails - or anyhow one of them - to grow so extremely long as manifestly to unfit them for any manual activity, thus making it perfectly clear to all that they were creatures too refined and elevated ever to engage in such employments. It is a gesture that cannot but appeal to the English, who surpass all other nations in snobbishness; our fastidious distaste for the applied sciences and for trade has played a large part in bringing England to the position in the world which she occupies today. The Limits of Science (1984)
Antipathy to science can become quite pettish. Listen to the novelist and feminist Fay Weldon's hymn of hate against 'the scientists', also in the Daily Telegraph, on 2 December 1991. (I imply nothing by this coincidence, for the paper has an energetic science editor and fine coverage of scientific topics):
Don't expect us to like you. You promised us too much and failed to deliver. You never even tried to answer the questions we all asked when we were six. Where did Aunt Maud go when she died? Where was she before she was bom?
Note that this accusation is the exact opposite of Bernard Levin's (that scientists don't know when they don't know). If I were to offer a simple
and direct best-guess answer to both those Aunt Maud questions, I'd certainly be called arrogant and presumptuous, going beyond what I could possibly know, going beyond the limits of science. Miss Weldon continues:
You think these questions are simplistic and embarrassing, but they're the ones which interest us. And who cares about half a second after the Big Bang; what about half a second before? And what about crop
circles? . . . The scientists just can't face the notion of a variable universe. We can.
She never makes clear who this all-inclusive, anti-scientific 'we' is, and she probably, by now, regrets the tone of her piece. But it is worth worrying where such naked hostility comes from.
Another example of anti-science, though in this case possibly intended to be funny, is a piece from A. A. Gill, a humorous loose cannon of a columnist in the Sunday Times of London (8 September 1996). He refers to science as constrained by experiment, and by the tedious, plodding stepping stones of empiricism. He contrasts it with art and with the theatre, with the magic of lights, fairy dust, music and applause.
There are stars and there are stars, darling. Some are dull, repetitive squiggles on paper, and some are fabulous, witty, thought-provoking, incredibly popular. . .
'Dull, repetitive squiggles' is a reference to the discovery of pulsars, by Bell and Hewish at Cambridge in 1967. Gill was reviewing a television programme in which the astronomer Jocelyn Bell Burnell recalled the spine-tingling moment when she first knew, looking at the print-out from Anthony Hewish's radio telescope, that she was seeing something hitherto unheard of in the universe. A young woman on the threshold of a career, the 'dull, repetitive squiggles' on her roll of paper spoke to her in tones of revolution. Not something new under the sun: a whole new kind of sun, a pulsar. Pulsars spin so fast that, where our planet takes 24 hours to rotate, a pulsar may take a fraction of a second. Yet the beam of energy that brings us the news, sweeping round like a lighthouse with such astonishing speed and clocking the seconds more accurately than a quartz crystal, may take millions of years to reach us. Darling, how too too tedious, how madly empirical, my dear! Give me fairy dust at the panto any day.
I do not think that such fretful, shallow antipathy results from the common tendency to shoot the messenger, or to blame science for political misuses like hydrogen bombs. No, the hostility I have quoted sounds to me more personally anguished, almost threatened,
beleaguered, fearful of humiliation because science is seen as too difficult to master. Oddly enough, I would not dare to go so far as John Carey, professor of English literature at Oxford, when he writes, in the preface to his admirable Faber Book of Science (1995):
The annual hordes competing for places on arts courses in British universities, and the trickle of science applicants, testify to the abandonment of science among the young. Though most academics are wary of saying it straight out, the general consensus seems to be that arts courses are popular because they are easier, and that most arts students would simply not be up to the intellectual demands of a science course.
Some of the more mathematical sciences may be hard, but nobody
should have trouble understanding the circulation of the blood and the heart's role in pumping it round. Carey relates how he quoted to a class of 30 undergraduates, in their final year reading English at a great university, Donne's lines, 'Knows't thou how blood, which to the heart doth flow,/Doth from one ventricle to the other go? ' Carey asked them how, as a matter of fact, the blood does flow. None of the 30 could answer, and one tentatively guessed that it might be 'by osmosis'. This is not just wrong. Even more spectacularly, it is dull. Dull compared to the truth that the total length of capillaries round which the heart pumps
the blood, from ventricle to ventricle, is more than 50 miles. If 50 miles of tubing are packed inside a human body, you can readily work out how finely and intricately ramified most of those tubes must be. I don't think any true scholar could fail to find this an arresting thought.
And unlike, say, quantum theory or relativity, it certainly isn't difficult to understand, though it may be difficult to credit. So I take a more charitable view than Professor Carey and wonder whether these young people had simply
been let down by scientists and insufficiently inspired by them. Perhaps an emphasis on practical experiment at school, while excellently suited
to some children, may be superfluous or positively counterproductive for those who are equally clever but clever in a different way.
Recently I did a television programme about science in our culture (it was, in fact, the one being reviewed by A. A. Gill). Among the many appreciative letters I received was one which poignantly began: 'I am a clarinet teacher whose only memory of science at school was a long period of studying the bunsen burner. ' The letter led me to reflect that it is possible to enjoy the Mozart concerto without being able to play the clarinet. In fact, you can learn to be an expert connoisseur of music without being able to play a note on any instrument. Of course, music would come to a halt if nobody ever learned to play it. But if everybody grew up thinking that music was synonymous with playing it, think how relatively impoverished many lives would be.
Couldn't we learn to think of science in the same way? It is certainly important that some people, indeed some of our brightest and best, should learn to do science as a practical subject. But couldn't we also teach science as something to read and rejoice in, like learning how to listen to music rather than slaving over five-finger exercises in order to play it? Keats shied away from the dissecting room, and who can blame him? Darwin did the same. Perhaps if he had been taught in a less practical way, Keats would have been more sympathetic to science and Newton.
It is here that I would seek rapprochement with Britain's best-known journalistic critic of science, Simon Jenkins, former editor of The Times. Jenkins is a more formidable adversary than the others I have quoted because he knows what he is talking about. He readily concedes that science books can be inspiring, but he resents the high profile science receives in modern compulsory education syllabuses. In a taped conversation with me in 1996, he said:
I can think of very few science books I've read that I've called useful. What they've been is wonderful. They've actually made me feel that the world around me is a much fuller, much more wonderful, much more awesome place than I ever realized it was. That has been, for me, the wonder of science. That's why science fiction retains its compelling fascination for people. That's why the move of science fiction into biology is so intriguing. I think that science has got a wonderful story to tell. But it isn't useful. It's not useful like a course in business studies or law is useful, or even a course in politics and economics.
Jenkins's view that science is not useful is so idiosyncratic that I shall pass over it. Usually even its sternest critics concede that science is useful, perhaps all too useful, while at the same time missing Jenkins's more important point that it can be wonderful. For them, science in its usefulness undermines our humanity or destroys the mystery on which poetry is sometimes thought to thrive. For another thoughtful British journalist, Bryan Appleyard, writing in 1992, science is doing 'appalling spiritual damage'. It is 'talking us into abandoning ourselves, our true selves'. Which brings me back to Keats and his rainbow, and leads us into the next chapter.
3
BARCODES IN THE STARS Nor ever yet
The melting rainbow's vernal-tinctur'd hues
To me have shone so pleasing, as when first
The hand of science pointed out the path In which the sun-beams gleaming from the west Fall on the wat'ry cloud, whose darksome veil Involves the orient, and that trickling show'r
Piercing thro' every crystalline convex
Of clust'ring dew-drops to their flight opposed,
Recoil at length where concave all behind
Th'intemal surface of each glassy orb
Repells their forward passage into air;
That thence direct they seek the radiant goal
From which their course began; and as they strike
In diff'rent lines the gazer's obvious eye,
Assume a different lustre, thro' the brede
Of colours changing from the splendid rose
To the pale violet's dejected hue.
MARK AKENSIDE, The Pleasures of Imagination (1744)
In December 1817 the English painter and critic Benjamin Haydon introduced John Keats to William Wordsworth at dinner in his London studio, together with Charles Lamb and others of the English literary circle. On view was Haydon's new painting of Christ entering Jerusalem, attended by the figures of Newton as a believer and Voltaire as a sceptic. Lamb, drunk, upbraided Haydon for painting Newton, 'a fellow who believed nothing unless it was as clear as the three sides of a triangle'. Newton, Keats agreed with Lamb, had destroyed all the poetry of the rainbow, by reducing it to the prismatic colours. 'It was impossible to resist him,' said Haydon, 'and we all drank "Newton's health, and confusion to mathematics". ' Years later, Haydon recalled this 'immortal dinner' in a letter to Wordsworth, his fellow survivor.
And don't you remember Keats proposing 'Confusion to the memory of Newton' and upon your insisting on an explanation before you drank it, his saying, 'Because he destroyed the poetry of the rainbow by reducing it to a prism ? Ah, my dear old friend, you and I shall never see such days again! Haydon,
Autobiography and Memoirs
Three years after Haydon's dinner, in his long poem 'Lamia' (1820), Keats wrote:
Do not all charms fly
At the mere touch of cold philosophy?
There was an awful rainbow once in heaven: We know her woof, her texture; she is given
In the dull catalogue of common things. Philosophy will clip an Angel's wings. Conquer all mysteries by rule and line. Empty the haunted air, and gnomed mine - Unweave a rainbow . . .
Wordsworth had better regard for science, and for Newton ('Voyaging through strange seas of thought, alone'). He also, in his preface to the Lyrical Ballads (1802), anticipated a time when 'The remotest discoveries of the chemist, the botanist, or mineralogist, will be as proper objects of the poet's art as any upon which it can be employed'.
His collaborator Coleridge said elsewhere that 'the souls of 500 Sir Isaac Newtons would go to the making up of a Shakespeare or a Milton'. This can be interpreted as the naked hostility of a leading Romantic against science in general, but the case of Coleridge is more complicated. He read a great deal of science and fancied himself as a scientific thinker, not least on the subject of light and colour, where he claimed to have anticipated Goethe. Some of Coleridge's scientific speculations have turned out to be plagiarisms, and he perhaps showed poor judgement over whom to plagiarize. It was not scientists in general that Coleridge anathematized, but Newton in particular. He had a high regard for Sir Humphry Davy, whose lectures he attended at the Royal Institution 'in order to renew my stock of metaphors'. He felt that Davy's discoveries, compared with Newton's, were 'more intellectual, more ennobling and impowering human nature'. His use of words like ennobling and impowering suggests that Coleridge's heart might have been in the right place with respect to science, if not with respect to Newton. But he failed to live up to his own ideals 'to unfold and arrange' his ideas in 'distinct, clear and communicable conceptions'. On the subject of the spectrum and unweaving the rainbow itself, in a letter of 1817 he became almost beside himself with confusion:
To me, I confess, Newton's positions, first, of a Ray of Light, as a physical synodical Individuum, secondly, that 7 specific individua are co-existent (by what copula? ) in this complex yet divisible Ray; thirdly that the Prism is a mere mechanic Dissector of this Ray; and lastly, that Light, as the common result, is - confusion
In another 1817 letter, Coleridge warms to his theme:
So again Colour is Gravitation under the power of Light, Yellow being the positive, blue the negative Pole, and Red the culmination or Equator; while Sound on the other hand is Light under the power or paramountcy of Gravitation.
Perhaps Coleridge was simply born too early to be a post-modernist:
The figure/ground distinction prevalent in Gravity's Rainbow is also evident in Vineland, although in a more self-supporting sense. Thus Derrida uses the term 'subsemioticist cultural theory' to denote the role of the reader as poet. Thus, the subject is contextualized into a postcultural capitalist theory that includes language as a paradox.
This is from http://www. cs. monash. edu. au/links/postmodern. html where a literally infinite quantity of similar nonsense can be found. The meaningless wordplays of modish francophone savants, splendidly exposed in Alan Sokal and Jean Bricmont's Intellectual Impostures (1998), seem to have no other function than to impress the gullible. They don't even want to be understood. A colleague confessed to an American devotee of post-modernism that she found his book very difficult to understand. 'Oh, thank you very much,' he smiled, obviously delighted at the compliment. Coleridge's scientific ramblings, by contrast, seem to show some genuine, if incoherent, desire to understand the world around him. We must set him on one side as a unique anomaly, and move on.
Why, in Keats's 'Lamia', is the philosophy of rule and line 'cold', and why do all charms flee before it? What is so threatening about reason? Mysteries do not lose their poetry when solved. Quite the contrary; the solution often turns out more beautiful than the puzzle and, in any case, when you have solved one mystery you uncover others, perhaps to inspire greater poetry. The distinguished theoretical physicist Richard Feynman was charged by a friend that a scientist misses the beauty of a flower by studying it. Feynman responded:
The beauty that is there for you is also available for me, too. But I see a deeper beauty that isn't so readily available to others. I can see the complicated interactions of the flower. The color of the flower is red. Does the fact that the plant has color mean that it evolved to attract insects? This adds a further question. Can insects see color? Do they have an aesthetic sense? And so on I don't see how studying a flower ever detracts from its beauty. It only adds.
from 'Remembering Richard Feynman', The Skeptical Inquirer (1988)
Newton's dissection of the rainbow into light of different wavelengths led on to Maxwell's theory of electro-magnetism and thence to Einstein's theory of special relativity. If you think the rainbow has poetic mystery, you should try relativity. Einstein himself openly made aesthetic judgements in science, and perhaps went too far. 'The most beautiful thing we can experience,' he said, 'is the mysterious. It is the source of all true art and science. ' Sir Arthur Eddington, whose own scientific
writings were noted for poetic flair, used the solar eclipse of 1919 to test General Relativity and returned from Principe Island to announce, in Banesh Hoffmann's phrase, that Germany was host to the greatest scientist of the age. I read those words with a catch in the throat, but Einstein himself took the triumph in his stride. Any other result and he would have been 'sorry for the dear Lord. The theory is correct. '
Isaac Newton made a private rainbow in a dark room. A small hole in a shutter admitted a sunbeam. In its path he placed his famous prism, which refracted (bent) the sunbeam through an angle, once as it penetrated the glass, then again as it passed through the farther facet into the air again. When the light fell on the far wall of Newton's room, the colours of the spectrum were clearly displayed. Newton was not the first to make an artificial rainbow with a prism, but he was the first to use it to demonstrate that white light is a mixture of different colours. The prism sorts them out by bending them through different angles, blue through a steeper angle than red; green, yellow and orange through intermediate angles. Others had, understandably, thought that a prism changed the quality of the light, positively tinting it rather than separating the colours out of an existing mixture. Newton clinched the matter in two experiments in which the light passed through a second prism. In his ''experimentum crucis', beyond the first prism he placed a slit which allowed only a small part of the spectrum to pass, say, the red portion. When this red light was again refracted by a second prism, only red light emerged. This showed that light is not qualitatively changed by a prism, merely separated out into components which would normally be mixed. In his other clinching experiment, Newton turned the second prism upside down. The spectral colours that had been fanned out by the first prism were brought together again by the second. What emerged was reconstituted white light.
The easiest way to understand the spectrum is through the wave theory of light. The thing about waves is that nothing actually travels all the way from source to destination. Such motion as there is, is local and small scale. Local motion triggers motion in the next local patch and so on, all the way along the line, like the famous football stadium wave. The
original wave theory of light was in turn supplanted by the quantum theory, according to which light is delivered as a stream of discrete photons. Physicists that I have pressed admit that photons stream away from the sun in a way that football fans do not travel from one end of the stadium to the other. Nevertheless, ingenious experiments in this
century have shown that even in the quantum theory photons still
behave like waves too. For many purposes, including ours in this chapter, we can forget quantum theory and treat light simply as waves propagating outwards from a light source, like ripples in a pond when a pebble is thrown in. But light waves travel incomparably faster and are
broadcast in three dimensions. To unweave the rainbow is to separate it into its components of different wavelengths. White light is a scrambled mixture of wavelengths, a visual cacophony. White objects reflect light of all wavelengths but, unlike mirrors, they scatter it into incoherence as they do so. This is why you see light, but not your face, reflected from a white wall. Black objects absorb light of all wavelengths. Coloured objects, by reason of the atomic structures of their pigments or surface layers, absorb light of some wavelengths and reflect other wavelengths. Plain glass allows light of all wavelengths to pass straight through it. Coloured glass transmits light of some wavelengths while absorbing light of other wavelengths.
What is it about the bending action of a glass prism or, under the right conditions, a drop of rain, that splits white light into its separate colours? And anyway, why are light beams bent by glass and water at all? The bending results from a slowing down of the light as it moves from air into glass (or water). It speeds up again as it emerges from the glass. How can this be, given Einstein's dictum that the velocity of light is the great physical constant of the universe, and nothing can go faster? The answer is that light's legendary full speed, represented by the symbol c, is attained only in a vacuum. When light travels through a transparent substance like glass or water, it is slowed down by a factor known as the 'refractive index' of that substance. It is slowed down by air, too, but less so.
But why does slowing down translate into a change of angle? If the light beam is pointing straight into a glass block, it will continue at the same angle (dead ahead) but slowed down. However, if it breaks the surface at an oblique angle, it is deflected to a shallower angle as it starts to travel more slowly. Why? Physicists have coined a 'Principle of Least Action' which, if not entirely satisfying as an ultimate explanation, at least makes it something we can empathize with. The matter is well explained in Peter Atkins's Creation Revisited (1992). Some physical entity, in this case a beam of light, behaves as if it is striving for economy, trying to minimize something. Imagine yourself a lifesaver on a beach, racing to save a drowning child. Every second counts, and you must take as little time as possible to reach the child. You can run faster than you can swim. Your course towards the child is initially over land and therefore fast, then through water and so much slower. Assuming that the child is not straight out to sea from where you are standing, how do you minimize your travel time? You could take the bee-line direction, minimizing distance, but this wouldn't minimize the time taken because it leaves too much of the journey in water. You could run straight to that point on the sea's edge which is immediately opposite the child, then swim straight out to sea. This maximizes running at the expense of swimming, but even this is not quite the fastest course because of the
greater total distance travelled. It is easy to see that the swiftest course is to run to the shore at a critical angle, which depends upon the ratio of your running speed to your swimming speed, then switch abruptly to a new angle for the swimming part of the journey. In terms of the analogy, swimming speed and running speed correspond to the refractive index of water and the refractive index of air. Of course light beams aren't deliberately 'trying' to minimize their travel time, but everything about their behaviour makes sense if you assume that they are doing the unconscious equivalent. The analogy can be made respectable in terms of quantum theory, but that is beyond my scope here and I recommend Atkins's book.
The spectrum depends upon light of different colours being slowed by different amounts: the refractive index of a given substance, say glass or water, is greater for blue light than for red. You could think of blue light as being a slower swimmer than red, getting tangled up in the undergrowth of atoms in glass or water because of its short wavelength. Light of all colours gets less tangled up among the sparser atoms of air, but blue still travels more slowly than red. In a vacuum, where there is
no undergrowth at all, light of all colours has the same velocity: the great, universal maximum c.
Raindrops have a more complicated effect than Newton's prism. Being roughly spherical, their back surface acts as a concave mirror. So they reflect the sunlight after refracting it, which is why we see the rainbow in the part of the sky opposite the sun, rather than when looking towards the sun through rain. Imagine that you are standing with your back to the sun, looking towards a shower of rain, preferably with a leaden background. We shan't see a rainbow if the sun is higher in the sky than 42 degrees above the horizon. The lower the sun, the higher the rainbow. As the sun rises in the morning, the rainbow, if one is visible, sets. As the sun sets in the evening, the rainbow rises. So let's assume that it is early morning or late afternoon. Think about a particular raindrop as a sphere. The sun is behind and slightly above you, and light from it enters the raindrop. At the boundary of air with water it is refracted and the different wavelengths that make up the sun's light are bent through different angles, as in Newton's prism. The fanned out colours go through the interior of the raindrop until they hit its concave far wall, where there they are reflected, back and down. They leave the raindrop again and some of them end up at your eye. As they pass from water back into air they are refracted for a second time, the different colours again being bent through different angles. So, a complete spectrum - red, orange, yellow, green, blue, violet - leaves our single raindrop, and a similar one leaves the other raindrops in the vicinity. But from any one raindrop, only a small part of the spectrum hits your eye. If your eye gets a beam of green light from one particular raindrop, the blue light from that
raindrop goes above your eye, and the red light from that particular raindrop goes below. So, why do you see a complete rainbow? Because there are lots of different raindrops. A band of thousands of raindrops is giving you green light (and simultaneously giving blue light to anybody who might be suitably placed above you, and simultaneously giving red light to somebody else below you). Another band of thousands of raindrops is giving you red light (and giving somebody else blue light . . . ), another band of thousands of raindrops is giving you blue light, and so on. The raindrops delivering red light to you are all at a fixed distance from you - which is why the red band is curved (you are the centre of the circle). The raindrops delivering green light to you are also at a fixed distance from you, but it is a shorter one. So the circle on which they sit has a smaller radius and the green curve sits inside the red curve. Then the blue curve sits inside that, and the whole rainbow is built up as a series of circles with you at the centre. Other observers will see different rainbows centred on themselves.
So, far from the rainbow being rooted at a particular 'place' where fairies might deposit a crock of gold, there are as many rainbows as there are eyes looking at the storm. Different observers, looking at the same shower from different places, will piece together their own separate rainbows using light from different collections of raindrops. Strictly speaking, even your two eyes are seeing two different rainbows. And as we drive along a road looking at 'one' rainbow, we are actually seeing a series of rainbows in quick succession. I think that if Wordsworth had realized all this, he might have improved upon 'My heart leaps up when I behold/A rainbow in the sky' (although I have to say it would be hard to improve on the lines that follow).
A further complication is that the raindrops themselves are falling, or blowing about.