Gilbert’s work was an instant success. Future work on magnetism and electricity all recognized its debt to Gilbert, but his importance went far beyond simply reform of those two disciplines. For the first time in history, Gilbert was performing modern, experimental science—and he knew it. In the preface to De Magnete, he wrote:
To you alone, true philosophers,…who not only in books but in things themselves look for knowledge, have I dedicated these foundations of magnetic science—a new style of philosophising. But if any see fit not to agree with the opinions here expressed and not to accept certain of my paradoxes, still let them note the great multitude of experiments and discoveries—these it is chiefly that cause all philosophy to flourish…Let whosoever would make the same experiments handle the bodies carefully, skilfully, and deftly, not heedlessly and bunglingly; when an experiment fails, let him not in his ignorance condemn our discoveries, for there is naught that has not been investigated again and again, done and repeated under our eyes. Many things in our reasonings and our hypotheses will perhaps seem hard to accept being at variance with the general opinion; but I have no doubt that they will win authoritativeness from the demonstrations themselves.
Gilbert is a marginal figure now. He didn’t possess the glamour of Galileo, the influence of Bacon, the genius of Newton, the precedence of Vesalius and Copernicus. Yet there, in his De Magnete, you can hear the authentic voice of modern science, spoken by the world’s first scientist, who sought his knowledge ‘not only in books but in things themselves’.
* A Belgian—a famous Belgian!
EX UNGUE LEONEM
In June 1696, the Swiss mathematician Johann Bernoulli published a letter to the mathematicians of Europe, challenging them to solve two problems that he had himself developed and solved, and proposing a six-month time limit for the solutions.* By Christmas of that year, nobody had come up with the answers, so Bernoulli extended the time limit by another year. On 29 January 1697, the challenge first came to the attention of Isaac Newton, then in his fifties and with his most productive years long behind him. Newton solved both problems overnight and, just for the hell of it, invented a more complex version of the second problem and solved that too. In all Bernoulli received four solutions to his challenge, including an anonymous one, authored by Newton. The lack of a signature didn’t deceive Bernoulli for a moment. He recognized the proof as Newton’s, ‘tanquam ex ungue leonem’, telling the lion by its claw.
The lion had been born in 1642, almost exactly a century after the Scientific Revolution had been launched by the twin efforts of Copernicus and Vesalius. A century on, and scientists were increasingly getting the hang of their new occupation: experimental, observational, mathematical. The Italian Accademia del Cimento, the English Royal Society and the French Académie des Sciences all set up shop between 1657 and 1666, just as the teenaged Newton was emerging into adulthood—the young man and the scientific community sharing the same coming of age.
Newton was an introverted child, with few close ties. His father, a minor landowner in the Lincolnshire hamlet of Woolsthorpe, died before he was born. Three years later, his mother remarried, taking as husband a prosperous rector twice her age. The new husband knew what he wanted—an attractive young wife, yes; an awkward stepson, no thanks—so the boy was palmed off on to a grandmother, who brought him up for the next seven years. At that point, the new husband had the good grace to drop dead, allowing his suddenly wealthy widow to return, three new kids in tow. (What Isaac thought about all this is, alas, not known.)
Locally schooled, the young lad was little suited to the rural life. He was fined for allowing his pigs to trespass, fined again for letting his fences fall into disrepair. At his uncle’s instigation, Newton was sent away to Cambridge in 1661, which, far from being as it is now a hotbed of the latest scientific thinking, was wedded to a Latin-and Greek-based curriculum that had changed little for aeons. All the same, Cambridge had books and Newton had time to read them. He read, thought, studied, asked questions, made notes. In 1665 the plague came to Cambridge. The university closed down. Newton went home, aged just twenty-three.
Back in Woolsthorpe, the pigs still no doubt ran riot, the fences still no doubt gaped with holes, yet Newton wasn’t completely useless. As he recalled later: ‘In November [1665, I] had the direct method of fluxions and the next year in January had the theory of colours and in May following I had entrance into ye inverse method of fluxions.’ ‘Fluxions’ was Newton’s term for the differential calculus, and the ‘inverse method’ his term for the integral calculus, which together form one of the most essential tools in mathematics.
And the same year I began to think of gravity extending to the orb of the Moon, and…I deduced that the forces which keep the Planets in their Orbs must be reciprocally as the squares of their distances from the centres about wch they revolve: and thereby compared the force requisite to keep the Moon in her Orb with the force of gravity at the surface of the earth, and found them answer pretty nearly. All this was in the plague years of 1665 and 1666. For in those days, I was in the prime of my age for invention and minded Mathematicks and Philosophy [that is, science] more than at any time since.
Newton hadn’t yet cracked the theory of gravitation, but he’d made the first emphatic breakthrough in thinking about it. More than that: he’d developed the mathematical tools he required for the mature theory to emerge. His account, just quoted, doesn’t mention his work on infinite series and the binomial theorem during those plague years, but his work in either field would have secured him a permanent place in the mathematical history books.
If you or I had just spent a couple of years producing the most important series of mathematical breakthroughs in the history of humankind, we’d probably want to tell someone about it. Not so Newton. He got back to Cambridge, became elected a Fellow of Trinity, and went on working (on cubic equations this time). He told nobody what he’d done. Fortunately, however, though Newton was reclusive and uncommunicative, he was also touchy. In 1668, one Nicholas Mercator published a book, Logarithmotechnia, which presented a few results in the study of infinite series. Newton—way ahead of the game, but hating others being given the credit—started to let his results and findings leak out, though often anonymously. His fame spread. Other mathematicians called on Newton for help. Teasingly, partially and unpredictably, he responded, so that while European mathematicians started to become aware of his powers, they were still very much in the dark as to what he had actually achieved.
In 1669 Newton was appointed Lucasian Professor of Mathematics at Cambridge, and quickly turned his attention to optics, another area he’d studied during those plague years in Woolsthorpe. Fresh from mathematics, Newton now turned his hand to the experimental. In the words of Rupert Hall, author of the classic text The Revolution in Science:
Spread over a series of years from 1664, perhaps ten years, Newton effected the greatest experimental investigation in all seventeenth-century physical science—indeed one of the greatest of all time…Newton created completely novel standards of scientific method both with regard to the accuracy and detail of an investigation, and of the closeness of relationships with experiments and theory.
For the crucial experiment, he darkened his room at Trinity College, allowing sunlight to enter only through a small round hole. That sunbeam was allowed to strike a glass prism, which split the beam into all colours of the spectrum. Thus far, he was in well-known territory—‘a pleasing divertisement’ but nothing more. What Newton noticed, however, was a phenomenon that no one else had taken interest in. The prism didn’t simply split the light beam, it elongated it, just as it would if different sorts of light were being differentially refracted by the prism—a testable hypothesis. Having separated white light into all seven colours through one prism, Newton used a second prism to refract the blue light that had emerged from the first. This blue light was once again refracted, but it was no longer elongated as abruptly, or split into colours. After a series of a
ccurate and minutely observed experiments, he drew the only possible conclusion: ‘Light itself is a heterogenous mixture of differently refrangible rays.’ The final proof was simply this: ‘all the Colours of the Prisme being made to converge…reproduced light, intirely and perfectly white’.
To a world that believed that white light was the ultimate symbol of purity—of God’s love, even—such a conclusion, which cast white light as nothing but the mongrel amalgam of everything going, was deeply shocking. Or rather: it would have been shocking if Newton had bothered to tell anyone. Characteristically, he did not. Instead, he was now hot on the trail of another goal. If light was a mixture, then the focal depth of blue light would be different from the focal depth of red light, and so on. One consequence of this fact was that no glass lens could focus without generating annoying coloured fringes around the image. Newton realized that light could be focused instead by reflection, ‘provided [that] a reflecting substance could be found, which would polish as finely as Glass, and reflect as much light as glass transmits, and the art of communicating to it a Parabolick figure be also attained’.
That was hardly a minor ask, but Newton knew just the man for the job: himself. The mathematician-turned-experimenter now turned technician. In his own furnace, Newton developed a tin-and-copper alloy which he used to cast his curved reflecting lens. He then ground that lens himself, using all his strength to bring the surface to a perfect reflective pitch. The result, finally, was a reflecting telescope just six inches long but as good as the best telescopes in London and Italy.
Did he tell anyone? Of course not. This was Newton. For two years, the new device remained virtually unknown. Then, one day, he lent the telescope to his Trinity colleague Isaac Barrow, who took it to the Royal Society in London. Fame suddenly broke over Newton’s head: welcome and unwelcome, intrusive and gratifying. For the first time in his life, Newton got ready to disclose something of consequence: ‘the oddest if not the most considerable detection which hath hitherto been made in the operations of Nature’.
His optical discoveries, published in 1672 in the Philosophical Transactions of the Royal Society, caused a storm. Newton loved the praise, but detested the inevitable arguments. When the great Robert Hooke had the cheek to refer to Newton’s conclusions as a mere ‘hypothesis’, Newton brooded over the supposed insult for several months, then wrote a rancorous and bitter reply, attacking Hooke personally and deliberately and needlessly widening the realm of disagreement.
For the rest of that decade, Newton remained largely withdrawn from public attention. His vendetta with Hooke ended, unreconciled, in 1676.* He passed his time in alchemical and scriptural researches. In both activities, Newton’s drive towards investigative completeness was as total as his drive in his other, more ‘modern’ pursuits. Newton didn’t simply read the Bible. He read it in English, Latin, Greek, Hebrew and French, and supplemented his biblical readings by consulting the writings of the early Church leaders, Athanasius, Arius, Origen, Eusebius, and many more besides. Newton’s writings on scripture would amount to millions of words, dozens of times the length of this book, far more than he ever wrote on maths or physics. In alchemy, the same thing. He built furnaces, which he used to melt, burn, distil, sublime and calcine. He poisoned himself with mercury. He was, though almost unknown, the greatest alchemist in Europe.
Newton might well have stayed with his furnaces and scriptures. When Hooke wrote to Newton in 1679 asking his opinion as to whether planetary orbits might be caused by some central attractive force, Newton replied, saying that he had ‘for some years past been endeavouring to bend my self from Philosophy…I am almost as little concerned about it as…a country man about learning’. Hooke persisted and soon managed to provoke Newton into a second quarrel, this time over how a body might fall to earth. Quarrelling, vendettas and claims of academic priority had always been the best way to get Newton to divulge his knowledge. This time, however, Newton kept his silence, though not before an exchange of letters had brought into sharp focus the problem of reconciling planetary motions, falling bodies and the mathematics of an attractive force. Never before had the problem been so accurately specified. Science stood waiting for an answer.
For four years—nothing. Among members of the London Royal Society, however, debate was escalating. There were a few ingredients in the pot already: Kepler’s rule of periods, an inverse square law of attraction, the elliptical movement of planets. Debate, ingredients, but no resolution. Then, in August 1684, the astronomer and scientist Edmond Halley made a trip to Cambridge, where he asked Newton the million-dollar question. If planets were reacting to a central attractive force, what shape would their orbits be? Casually, Newton replied that the shape would be an ellipse; that he could prove it; that he’d known it for years; that he’d dig out the proof and send it on. Halley was flabbergasted. Newton, in effect, was saying that he’d solved the central scientific question of the age and had told no one.
From that point on, no one was going to let Newton keep his silence any longer. His first paper on the topic, a short piece of just nine pages, caused a storm of excitement. Under the pressure of excitement, outward and inner, he began to drive himself to systematize his own only partially formed insights. The recluse became ever more reclusive. He left aside his alchemy and his scripture. He ate standing up. If he went outside, he looked lost, distracted, and soon returned indoors. He wrote obsessively. The result, delivered to Halley in April 1686, was quite simply the greatest intellectual achievement in human history: Book 1 of the Philosophiae Naturalis Principia Mathematica. Book 2 was already mostly complete, and Book 3 wouldn’t be far behind (once Newton had got another quarrel with Hooke out of the way, that is).
What did the completed Principia Mathematica achieve? It achieved everything. It gave precise definitions to concepts such as weight, mass, force: terms that had never before had exact expression. It defined the laws of motion. It contained the law of gravity. It proved the key postulates of gravitational theory, such as the elliptical movement of planets, or the way that a massive spherical object, such as the earth, was mathematically equivalent to a single point of equal mass located at the centre. It explained phenomena: the tides, the passage of comets, the motion of the moon. It made predictions: that the earth was not a true sphere, but a flattened one; that comets could return, in a slingshot action, past the sun. It contained massively detailed computations: reconciling observations of the moons of Jupiter with the mathematics of their orbital periods and distances from the planet. Ditto for Mercury, Venus, Mars, Jupiter, Saturn and the moon. It calculated the density of the planets, explained the precession or movement of the earth’s axis. It was also a how-to book: how to locate a body travelling a given parabola at a given time; how to find the velocity of waves; how to determine an orbit without knowing a focus. If the book had done half of what it actually did—a third, a tenth—it would still have been the greatest work of science in history. As it was, it introduced the modern age of mathematical, physical and scientific knowledge as emphatically and decisively as it was possible to conceive. What the Glorious Revolution was to do for English and British politics, the Principia did for knowledge itself.
That’s not to say it was all correct. It wasn’t. Book 2 of the Principia may have inaugurated an entirely new field (rational fluid mechanics), and it may have demolished for ever the old Cartesian view of planets swimming in some invisible ether, yet the book was riddled with errors, albeit ones so abstruse that it would take more than a century to sort them out. Nor was the book entirely straight with its reader. Having calculated the speed of falling bodies on earth, Newton wanted to demonstrate that his predictions were borne out by reality. Since no sufficiently accurate measurements existed, Newton simply used those he had available and pretended to greater accuracy than really existed. Modernity also arrived dressed in curious clothes. While Newton’s argument was entirely modern in its reliance on infinitesimals and calculus-based modes of thought, it was defi
antly classical in its use of Euclidian-style geometrical proofs and magisterial Latin prose.
Newton went on to live a long life. He became rich. He pursued his intellectual vendettas with a wholly needless intensity. (When Leibniz independently invented calculus, Newton savaged him and pursued him for years. English mathematics was deeply harmed by the feud.) He became not just the head of the Royal Society, but its Hooke-hating, Flamsteed-belittling autocrat. He became Warden, later Master, of the Royal Mint. On his deathbed, in 1727 at the great age of eighty-four, he refused the sacrament of the Church, his heretical, anti-Trinitarian views finally obtaining their full expression.
So immense is Newton, so much greater was he than those who stood around him, it’s easy to miss one final point. Newton was a genius, one of the greatest ever, but he was not an isolated one. Although the scientific revolution had been born in Italy, it didn’t long stay there, migrating north, passing through France and coming to rest in England. The oddness of this is easy to overlook. The English scientific community wasn’t simply the largest in Europe, it was by far the largest. Even if you discount the idle, useless or dilettante members of the Royal Society, its core of serious scientists was by a distance the largest such community in the world. Yet England was then a small country, with a population less than half that of Italy, about a third the size of France or Germany. Though the country was becoming more prosperous, it was coming from some way behind. The Netherlands was still by far the wealthiest country in Europe per head. Britain ranked about the same as Italy; somewhat better than France and Germany. Whatever was going on can’t be accounted for by either wealth or population.
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