Died: 1727, London, England
Major Works: Philosophiae naturalis principia mathematica (1687, 1713, 1726), Opticks (1704, 1717, 1721, 1730)
Invention of differential and integral calculus.
Clarification of concepts of inertia and force.
Formulation of three laws of motion, making possible the science of rational mechanics.
Proof of the composite nature of white light.
Construction of the first reflecting telescope.
Insistence on the experimental basis of true science.
Isaac Newton brought the foundations of physics into the form that remains the starting point today for every student of science. After the inconclusive struggles of Galileo and his other predecessors, it was only with Newton that Aristotle's retrogressive concept of falling bodies "seeking their natural place" finally and decisively died. The mathematical and philosophical aspects of Newton's work deeply affected. the science and eventually the whole learned culture of the century that followed. His creative genius was so striking that he became a challenging role model for every physicist since, as well as an icon representing science in the public mind in a way never approached by anyone other than Einstein.
Large portions of Newton's voluminous papers were never available to historians until recent decades. Their study has replaced the traditional overly heroic image with that of a much more complex man, major parts of whose life and activities are surprisingly at odds with the modern idea of dedication to rational science.
Newton's father was a successful but not wealthy farmer in rural Lincolnshire, who died several months before Isaac's birth. His mother Hannah remarried three years later (this time into significant wealth), but left young Isaac to spend most of his childhood in his grandmother's care. He thoroughly disliked his aged stepfather, after whose death Newton's, mother returned when he was ten, bringing three younger children with her. These must be major contributing factors to his dour and suspicious personality, which isolated Newton from his peers and led to repeated harsh disputes that poisoned most of his life.
Young Isaac received a few years of schooling in the neighboring village of Grantham, where he exhibited strong curiosity and mechanical aptitude. A brief period during adolescence of attempted grooming to run the family estate was a debacle, and the intervention of some who recognized his true talents enabled him to enter Cambridge University at eighteen. But the academic condition of Cambridge during the turmoil of the Civil War and the Stuart Restoration was an embarrassment; its main advantages for him seem to have been the freedom to devote himself to study and the books to do it with, and he largely taught himself. (The famous retreat from Cambridge to his country home during the Plague Years may not have made much difference in his intellectual activities.) After receiving his bachelor's degree in 1665, he remained in Trinity College, where he became a permanent fellow in 1667. To this was added the M.A. in 1668 and the Lucasian Professorship of Mathematics in 1669.
Cambridge in general and Trinity in particular were in a period of disastrous decline during Newton's tenure, and neither lecturing nor tutoring made significant demands. He applied most of his time to study of natural philosophy, mathematics, alchemy, even history and theology. He always did this with a characteristic thoroughness and intensity that not only conquered every subject but earned him a reputation for staying up all night and forgetting whether he had eaten his meals. His studies were done for his own satisfaction and were usually left in somewhat unfinished states as he jumped on to other interests. He did not merely neglect to publish important work but generally showed considerable aversion to doing so. The jealous, hostile reaction from Robert Hooke to Newton's first paper, submitted to the Royal Society in 1672, probably only reinforced Newton's native tendency to withhold his work from criticism.
After a deep psychological crisis in 1693 (the reasons for which remain subject to debate), Newton's creative work was effectively ended. Having become involved in university politics in the late 1 680s and elected to the Convention Parliament of 1689, his interests became more and more centered in London. He gained political appointments in the Mint as warden (1696) and master (1699), remaining in the latter post to the end of his life. These ordinarily would have been sinecures, but he brought his characteristic intensity to the positions and was one of the first prominent exemplars of the radical concept of responsible civil service.
As an undergraduate, Newton was greatly stimulated by both the natural philosophy and the analytic geometry of Rene Descartes, and his first investigations in mathematics and optics grew directly from that interest. Twenty years later he asserted his independence not only by rejecting the physics and philosophy of Descartes but by denigrating his analysis as well. Most of Newton's original work in mathematics was done in 1664-66, but published only much later or not at all. (John Collins urged him in vain to publish in the early 1670s. Work on a book in the early 1690s was aborted, and some of the material later ended up in the Opticks. The Arithmetica universalis of 1707 was put out by Whiston, and represented a rather thrown-together collection of Newton's earlier work.)
The Invention of Calculus
Newton made important contributions to the theory of infinite series, including the invention of a "Taylor series" twenty years before Brook Taylor. Aspects of that work and of John Wallis's "method of indivisibles" led him to invent new methods for dealing with the problems of quadratures and tangents of curves, resulting in what we now know as the calculus. (The notation and terminology most used today is that of his rival Leibniz, who developed the calculus a few years later independently of Newton.) He also did important work on the classification of cubic forms.
In those same years, 1664 to 1666, Newton also made many experiments on the refraction of light, especially its dispersion by prisms. In particular, he showed not only that sunlight could be separated into spectral colors but also that recombining those colors produced white light again. Many other ingenious experiments answered various objections and clearly established that different colors were different kinds of light, not merely modifications or differences in strength of a single kind. Newton also observed comets and learned how to grind lenses. It was his invention of the reflecting telescope that brought him recognition and membership in the Royal Society of London in 1672. He then submitted a paper on his theory of colors, in which unfortunately two major issues were not kept separate. Newton's particulate view of light was contrary both to popular notions of vibrations or vortices in a pervading ether and to interference phenomena he and others had observed in thin films, and in hindsight we can se e that he was wrong. But his revolutionary demonstration of the composite nature of white light, while equally unpopular in some circles, was exactly on target. Partly due to confusion of these issues, there was a very bitter exchange between Newton and Hooke, which contributed much to Newton's reluctance to publish his other work. Though Newton's own contributions to optics were essentially complete at this time, he did not write most of the Opticks until twenty years later, and he delayed its publication another ten years beyond that until after Hooke's death.
Newton's Laws of Motion
Newton was also well started on his study of motion and gravitation in the mid-1660s, though he went on to other things before making it into a coherent whole But the threat around 1680 that Robert Hooke was going to take credit for some of the ideas Newton had been sitting on drew him back to the subject, and it was the writing of the Principia from 1684 to 1687 that forced him to clarify his ideas and produce his laws of motion as we now know them:
1. Any massive object persists in its state of rest or of motion unless an external force acts upon it
2. An external force produces acceleration proportional to that force and inversely proportional to the mass upon which it acts.
3. For every force acting on a body there is an equal and opposite reaction from the body upon its neighbors
The help and encouragement of Edmond Halley was very important in finishing the Principia, but not in the sense that Halley wrested from Newton's grasp a work that had lain already complete for many years. The key to this step forward came only with persistent effort and lay in emphasizing the property of inertia and clearly differentiating it from external forces especially in the case of uniform circular motion; in fact, this was not fully achieved until the second edition. Recognition of the laws of motion and of the inverse-square law of universal gravitation were strongly linked with each other, since motions of planets and comets provide the clearest test for any theory of motion. The competing vortex theory of Descartes was quite explicitly debunked.
Newton's predecessors (especially Galileo) and contemporaries (such as Christiaan Huygens and Hooke) had achieved considerable partial understanding of these laws But it was Newton's crystallization of' the physics, coupled with his new mathematical techniques for extracting predictions from these general laws, that clearly was the launching point for physics as a well-founded quantitative science. He demonstrated its power by explaining the ocean tides, the moon's motion under the combined influence of earth and sun, the mutual perturbations of Jupiter and Saturn, the orbits of comets, the nonspherical figure of the earth, and the equinoctial precession.
Major portions of Newton's career were taken up with studies of a very different nature. He gathered voluminous material on alchemy and performed many experiments himself; his personal "Index chemicus," never published, is probably the most thorough survey of aichemical literature ever made. He seems to have hoped that a quantitative approach, together with concepts of universal interparticle attractions somewhat analogous to gravity, would turn this, too, into a unified and rational science. Newton also delved deeply into theology and interpretation of prophecies, and related questions of ancient history. He worked for many years on The Chronology of Ancient Kingdoms Amended, which was published the year after his death. In his own eyes this was another major work, but to us it seems that he was not as good a historian as he was a physicist, allowing his work to be too much influenced by religious presuppositions. Part of Newton's isolation from the society around him lay in his holding strong Arian beliefs (a form of Unitarianism) at a time when only Trinitarian doctrine was publicly acceptable; if his true beliefs had become known, even he would have lost position and respect as did his friend and follower William Whiston. (It must have been a bitter private irony for him to be for so many years a fellow of Trinity College.)
Also of interest is Newton's role in the Royal Society of London, which had been founded in 1662 during his undergraduate days and had received him into membership in 1672. His rivalry with Robert Hooke lasted until Hooke's death in 1703, and was one factor in his remaining at arm's length from most Society activities for three decades, even after he lived in London. At the turn of the century the Society might fairly be described as moribund; its first generation had passed on, many of the members were only dilettantes, and it staggered through several years with presidents chosen purely for their political influence and with no interest whatever in science. Newton deserves some credit for the Society's revival after his election to the presidency in late 1703. He did not hesitate to capitalize on his fame to retain that post until his death, and at times was insufferably autocratic. To Newton's great discredit, he used the Royal Society as a tool in the second and third great vendettas of his life. The for mer was with Astronomer Royal John Flamsteed, over control of the publication of the monumental star catalog that was his lifework. The latter was the dispute with the German philosopher--mathematician Gottfried Wilhelm Leibniz over priority in the invention of calculus. We now know that a report favoring Newton from a supposedly neutral committee set up by the Society was in fact largely ghostwritten by Newton himself. One wonders in vain whether his obsessive and vindictive personality stood in the way of his being an even greater figure than he is in the history of thought, or whether that anguished intensity was what somehow made his creativity possible.
The Necessity for Experimentation
For much of his life, Newton was usually content to let others make public statements about philosophical and theological issues; this reflected both his natural reticence and the need to avoid the doctrine of the Trinity. Newton's most careful statements about the foundations of his work come in the General Scholium to the Principia and the "Queries" at the end of the Opticks, particularly in the second and later editions. He insisted that natural science must be firmly based on experiment, though he showed very little concern for applied science. "For since the qualities of bodies are only known to us by experiments, we are to hold for universal all such as universally agree with experiments ... We are certainly not to relinquish the evidence of experiments for the sake of dreams and vain fictions of our own devising."
Newton's work in optics especially shows him putting this into practice; there is both a sustained series of experiments in order to rule out other interpretations, and a care for both quantitative description and accuracy in measurement. He was also suspicious of multiple ad hoc explanations, insisting that science should be based on principles with broad explanatory power: 'And what certainty can there be in a Philosophy which consists in as many Hypotheses as there are Phaenomena to be explained[?]"
Newton's law of universal gravitation says that two massive bodies affect each other at any distance, even across empty space, and this was philosophically disturbing. He was criticized by Leibniz and others for introducing "occult quantities" into science. His most famous statement, "I frame no hypotheses," should not be given too much weight out of context. It comes from the second edition of the Principia and is essentially a defensive position, designed to force the issue that we must accept the empirical evidence that there is an inverse-square interaction quite apart from whether we even attempt any detailed picture of how that action is transmitted: "It is enough that gravitation actually exists and acts according to the laws we have exposed." In a letter to Richard Bentley, he said, "Gravity must be caused by an agent acting constantly according to certain laws, but whether this agent be material or immaterial is a question I have left to the consideration of my readers." Newton had certainly explore d some imaginative hypotheses of his own, for instance, about possible relations of gravity to chemical affinity or electrical action, but knew when he did not have proof for them.
Newton saw knowledge both as power over things and as revelation of God; he said he had written the Principia "not with a design of bidding defiance to the Creator but to enforce and demonstrate the power & superintendency of a supreme being." His impact upon eighteenth-century philosophy is not entirely what he would have intended. David Hume in particular was responsible for transforming Newton's metaphysics by dealing God out of the picture, leading to the extreme a century later of Laplace's remark about God, "I have no need of that hypothesis." While Newton did develop a mechanistic world picture with atoms, void, and action at a distance, it was by no means a self sufficient world. He would have disagreed with the deist caricature of a God who sets the world in motion like winding up a clock and leaves it to run itself, just as vehemently as he did with the Cartesian vortex cosmology. Newton's God was immanent, continually and directly responsible for making things run in such an orderly way. So "Newt onianism" in its later incarnations is not something Newton himself would have subscribed to.
Andrade, E. N. da C. Sir Isaac Newton. London, 1954; reprint: Westport, Conn.: Greenwood, 1979. Best of the many older short popular biographies.
Brewster, Sir David. Memoirs of the Life, Writings, and Discoveries of Sir Isaac Newton. 2 vols. Edinburgh: T. Constable, 1855. The classic biography of Newton.
Christianson, Gale E. In the Presence of the Creator: Isaac Newton & His Times. New York: Macmillan, 1984. An excellent new general biography.
Cohen, I. B. The Newtonian Revolution in Science and Its Intellectual Significance. Norwalk, Conn.: Burndy Library, 1987. Views of a leading Newton scholar.
Herivel, John. The Background to Newton's Principia. Oxford: Clarendon Press, 1965. Detailed study of the development of Newton's work from 1664 to 1684.
Manuel, Frank E. A Portrait of Isaac Newton. Cambridge: Harvard University Press, 1968. Speculative psychological biography, influential in modern revision of the traditional heroic picture of Newton. For balancing critical comments, see Westfall.
Palter, Robert, ed. The Annus Mirabilis of Sir Isaac Newton, 1666-1966. Cambridge, Mass.: MIT Press, 1970. Proceedings of a symposium on the 300th anniversary.
Wallis, Peter, and Ruth Wallis. Newton and Newtoniana, 1672-1975. Folkestone, England: Dawson, 1977. An exhaustive bibliography.
Westfall, Richard S. Never at Rest: A Biography of Isaac Newton. Cambridge: Cambridge University Press, 1980. A thorough and extensive scientific biography, including a valuable bibliographical essay as an appendix.
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|Author:||HALL, DONALD E.|
|Publication:||Great Thinkers of the Western World|
|Date:||Jan 1, 1999|
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