Sir Isaac Newton dispersing sunlight through a prism for a study of optics, engraving after a picture by J.A. Houston, published c. 1879.
Connections
opponent: Gottfried von Leibniz
Gottfried Wilhelm Leibniz
Academic advisor: Isaac Barrow
Isaac Barrow (October 1630 – 4 May 1677) was an English Christian theologian and mathematician who is generally given credit for his early role in the development of infinitesimal calculus.
(In his monumental 1687 work, Philosophiae Naturalis Princ...)
In his monumental 1687 work, Philosophiae Naturalis Principia Mathematica, known familiarly as the Principia, Isaac Newton laid out in mathematical terms the principles of time, force, and motion that have guided the development of modern physical science. Even after more than three centuries and the revolutions of Einsteinian relativity and quantum mechanics, Newtonian physics continues to account for many of the phenomena of the observed world, and Newtonian celestial dynamics is used to determine the orbits of our space vehicles.
Opticks: Or, a Treatise of the Reflections, Refractions, Inflections, and Colors of Light
(Sir Isaac Newton (1642-1727) is without a doubt one of th...)
Sir Isaac Newton (1642-1727) is without a doubt one of the most well-known and influential scientists in history; he made incalculable contributions to the fields of physics, mathematics, astronomy, philosophy and theology. From 1670 to 1672, Newton lectured on optics while developing his theory of color. This led to his invention of the refracting telescope in 1672, which would correct chromatic aberration in the traditional refracting telescope, and so impressed the Royal Society that they encouraged him to publish his work. "Opticks" was Newton's second major contribution in this field, and offered new insights into the nature of color, light, and the phenomena of diffraction. The book also includes Newton's Queries, which address a wide range of physical phenomena, include the nature and transmission of heat, the possible cause of gravity, electrical phenomena, chemical action, and ethics of both science and human conduct.
(This great work supplied the momentum for the Scientific ...)
This great work supplied the momentum for the Scientific Revolution and dominated physics for over 200 years. It was the ancient opinion of not a few, in the earliest ages of philosophy, that the fixed stars stood immoveable in the highest parts of the world; that, under the fixed stars the planets were carried about the sun; that the earth, us one of the planets, described an annual course about the sun, while by a diurnal motion it was in the meantime revolved about its own axis; and that the sun, as the common fire which served to warm the whole, was fixed in the centre of the universe.
Observations upon the Prophecies of Daniel and the Apocalypse of St. John
(Observations upon the Prophecies of Daniel and the Apocal...)
Observations upon the Prophecies of Daniel and the Apocalypse of St. John, by Sir Isaac Newton, was originally published posthumously in 1733. The work is a collection of fragments on the books of Daniel and the Apocalypse of St. John, assembled by Newton's half-nephew Benjamin Smith. Within the work, Newton looks into the writings of ancient historians to show the coming fulfillment of the prophecies in the book of Daniel and the Apocalypse of St. John, including the coming of the Messiah.
Sir Isaac Newton was an English physicist and mathematician, who was the key figure of the scientific revolution of the 17th century. He made a number of important scientific contributions, including laying the foundation of classical mechanics.
Background
Isaac Newton was born on January 4, 1643, in Woolsthorpe, Lincolnshire, England. His father, also named Isaac Newton, had died three months before. His mother, Hannah Ayscough, married the rector of a neighboring parish, leaving Isaac at Woolsthorpe in the care of his grandmother, Margery Ayscough. For nine years Isaac was effectively separated from his mother, and his pronounced psychotic tendencies have been ascribed to this traumatic event. Newton disliked his stepfather. When he examined the state of his soul in 1662 and compiled a catalog of sins in shorthand, he remembered “Threatening my father and mother Smith to burn them and the house over them.” The acute sense of insecurity that rendered him obsessively anxious when his work was published and irrationally violent when he defended it accompanied Newton throughout his life and can plausibly be traced to his early years.
After his mother was widowed a second time, she determined that her first-born son should manage her now considerable property. It quickly became apparent, however, that this would be a disaster, both for the estate and for Newton. He could not bring himself to concentrate on rural affairs - set to watch the cattle, he would curl up under a tree with a book.
Education
After a rudimentary education in local schools, he was sent at the age of 12 to the King's School in Grantham, where he lived in the home of an apothecary named Clark. It was from Clark's stepdaughter that Newton's biographer William Stukeley learned many years later of the boy's interest in her father's chemical library and laboratory and of the windmill run by a live mouse, the floating lanterns, sundials, and other mechanical contrivances Newton built to amuse her. Although she married someone else and he never married, she was the one person for whom Newton seems to have had a romantic attachment.
At birth, Newton was heir to the modest estate which, when he came of age, he was expected to manage. But during a trial period midway in his course at King's School, it became apparent that farming was not his métier. In 1661, at the age of 19, he entered Trinity College, Cambridge. He started as a subsizar - paying his way by performing valet's duties - until he was awarded a scholarship in 1664. There the questioning of long-accepted beliefs was beginning to be apparent in new attitudes toward man's environment, expressed in the attention given to mathematics and science.
After receiving his bachelor's degree in 1665, apparently without special distinction, Newton stayed on for his master's; but an epidemic of the plague caused the university to close. Newton was back at Woolsthorpe for 18 months in 1666 and 1667. During this brief period, he performed the basic experiments and apparently did the fundamental thinking for all his subsequent work on gravitation and optics and developed for his own use his system of calculus. The story that the idea of universal gravitation was suggested to him by the falling of an apple seems to be authentic: Stukeley reports that he heard it from Newton himself.
Returning to Cambridge in 1667, Newton quickly completed the requirements for his master's degree and then entered upon a period of elaboration of the work begun at Woolsthorpe.
Newton's mathematics professor, Isaac Barrow, was the first to recognize his unusual ability, and when, in 1669, Barrow resigned to devote himself to theology, he recommended Newton as his successor. Newton became Lucasian professor of mathematics at 27 and stayed at Trinity in that capacity for 27 years.
Newton's main interest at the time of his appointment was optics, and for several years the lectures required of him by the professorship were devoted to this subject. In a letter of 1672 to the secretary of the Royal Society, he says that in 1666 he had bought a prism "to try therewith the celebrated phenomena of colours." He continues, "In order thereto having darkened the room and made a small hole in my window-shuts to let in a convenient quantity of the Suns light, I placed my prism at its entrance, that it might be thereby refracted to the opposite wall." He had been surprised to see the various colors appear on the wall in an oblong arrangement (the vertical being the greater dimension), "which according to the received laws of refraction should have been circular." Proceeding from this experiment through several stages to the "crucial" one, in which he had isolated a single ray and found it unchanging in color and refrangibility, he had drawn the revolutionary conclusion that "Light itself is a heterogeneous mixture of differently refrangible rays."
These experiments had grown out of Newton's interest in improving the effectiveness of telescopes, and his discoveries about the nature and composition of light had led him to believe that greater accuracy could not be achieved in instruments based on the refractive principle. He had turned, consequently, to suggestions for a reflecting telescope made by earlier investigators but never tested in an actual instrument. Being manually dexterous, he built several models in which the image was viewed in a concave mirror through an eyepiece in the side of the tube. In 1672 he sent one of these to the Royal Society.
Newton felt honored when the members were favorably impressed by the efficiency of his small reflecting telescope and when on the basis of it they elected him to their membership. But when this warm reception induced him to send the society a paper describing his experiments on light and his conclusions drawn from them, the results were almost disastrous for him and for posterity. The paper was published in the society's Philosophical Transactions, and the reactions of English and Continental scientists, led by Robert Hooke and Christiaan Huygens, ranged from skepticism to bitter opposition to conclusions which seemed to invalidate the prevalent wave theory of light.
At first Newton patiently answered objections with further explanations, but when these produced only more negative responses, he finally became irritated and vowed he would never publish again, even threatening to give up scientific investigation altogether. Several years later, and only through the tireless efforts of the astronomer Edmund Halley, Newton was persuaded to put together the results of his work on the laws of motion, which became the great Principia.
Newton's magnum opus, Philosophiae Naturalis Principia Mathematica, to give it its full title, was completed in 18 months - a prodigious accomplishment. It was first published in Latin in 1687 when Newton was 45. Its appearance established him as the leading scientist of his time, not only in England but in the entire Western world. In the Principia, Newton demonstrated for the first time that celestial bodies follow the laws of dynamics and, formulating the law of universal gravitation, gave mathematical solutions to most of the problems concerning motion which had engaged the attention of earlier and contemporary scientists. Book 1 treats the motion of bodies in purely mathematical terms. Book 2 deals with motion in resistant mediums, that is, in physical reality. In Book 3, Newton describes a cosmos based on the laws he has established. He demonstrates the use of these laws in determining the density of the earth, the masses of the sun and of planets having satellites, and the trajectory of a comet; and he explains the variations in the moon's motion, the precession of the equinoxes, the variation in gravitational acceleration with latitude, and the motion of the tides. What seems to have been an early version of book 3, published posthumously as The System of the World, contains Newton's calculation, with illustrative diagram, of the manner in which, according to the law of centripetal force, a projectile could be made to go into orbit around the earth.
In the years after Newton's election to the Royal Society, the thinking of his colleagues and of scholars generally had been developing along lines similar to those which he had taken, and they were more receptive to his explanations of the behavior of bodies moving according to the laws of motion than they had been to his theories about the nature of light. Yet the Principia presented a stumbling block: its extremely condensed mathematical form made it difficult for even the most acute minds to follow. Those who did understand it saw that it needed simplification and interpretation. As a result, in the 40 years from 1687 to Newton's death the Principia was the basis of numerous books and articles. These included a few peevish attacks, but by far the greater number were explanations and elaborations of what had subtly evolved in the minds of his contemporaries from "Mr. Newton's theories" to the "Newtonian philosophy."
The publication of the Principia was the climax of Newton's professional life. It was followed by a period of depression and lack of interest in scientific matters. He became interested in university politics and was elected a representative of the university in Parliament. Later he asked friends in London to help him obtain a government appointment. The result was that in 1696, at the age of 54, he left Cambridge to become warden and then master of the Mint. The position was intended to be something of a sinecure, but he took it just as seriously as he had his scientific pursuits and made changes in the English monetary system that was effective for 150 years.
Newton's London life lasted as long as his Lucasian professorship. During that time he received many honors, including the first knighthood conferred for scientific achievement and election to life presidency of the Royal Society. In 1704, when Huygens and Hooke were no longer living, he published the Opticks, mainly a compilation of earlier research, and subsequently revised it three times; he supervised the two revisions of the Principia; he engaged in the regrettable controversy with G. W. von Leibniz over the invention of the calculus; he carried on a correspondence with scientists all over Great Britain and Europe; he continued his study and investigation in various fields; and, until his very last years, he conscientiously performed his duties at the Mint.
In the interval between publication of the Principia in 1687 and the appearance of the Opticks in 1704, the trend was away from the use of Latin for all scholarly writing. The Opticks was written and originally published in English (a Latin translation appeared 2 years later) and was consequently accessible to a wide range of readers in England. The reputation which the Principia had established for its author of course prepared the way for acceptance of his second published work. Furthermore, its content and manner of presentation made the Opticks more approachable. It was essentially an account of experiments performed by Newton himself and his conclusions drawn from them, and it had greater appeal for the experimental temper of the educated public of the time than the more theoretical and mathematical Principia.
Of great interest for scientists generally were the queries with which Newton concluded the text of the Opticks - for example, "Do not Bodies act upon Light at a distance, and by their action bend its rays?" These queries (16 in the first edition, subsequently increased to 31) constitute a unique expression of Newton's philosophy; posing them as negative questions made it possible for him to suggest ideas which he could not support by experimental evidence or mathematical proof but which gave stimulus and direction to further research for many generations of scientists. "Of the Species and Magnitude of Curvilinear Figures," two treatises included with the original edition of the Opticks, was the first purely mathematical work Newton had published.
Newton's mathematical genius had been stimulated in his early years at Cambridge by his work under Barrow, which included a thorough grounding in Greek mathematics as well as in the recent work of René Descartes and of John Wallis. During his undergraduate years, Newton had discovered what is known as the binomial theorem; the invention of the calculus had followed; mathematical questions had been treated at length in correspondence with scientists in England and abroad, and his contributions to optics and celestial mechanics could be said to be his mathematical formulation of their principles.
But it was not until the controversy over the discovery of the calculus that Newton published mathematical work as such. The controversy, begun in 1699, when Fatio de Duillier made the first accusation of plagiarism against Leibniz, continued sporadically for nearly 20 years, not completely subsiding even with Leibniz's death in 1716.
The inclusion of the two tracts in the first edition of the Opticks was certainly related to the controversy, then in progress, and the appearance of other tracts in 1707 and 1711 under the editorship of younger colleagues suggests Newton's release of this material under pressure from his supporters. These tracts were for the most part revisions of the results of early research long since incorporated in Newton's working equipment. In the second edition of the Principia, of 1713, the four "Regulae Philosophandi" and the four-page "Scholium Generale" added to book 3 were apparently also designed to answer critics on the Continent who were expressing their partisanship for Leibniz by attacking any statement of Newton's that could not be confirmed by mathematical proof; the "Scholium" is of special interest in that it gives an insight into Newton's way of thought which the more austere style of the main text precludes.
Two other areas to which Newton devoted much attention were chronology and theology. A shortened form of his Chronology of Ancient Kingdoms appeared without his consent in 1725, inducing him to prepare the longer work for publication; it did not actually appear until after his death. In it, Newton attempted to correlate Egyptian, Greek, and Hebrew history and mythology and for the first time made use of astronomical references in ancient texts to establish dates of historical events. In his Observations upon the Prophecies of Daniel and the Apocalypse of St. John, also posthumously published, his aim was to show that the prophecies of the Old and New Testaments had so far been fulfilled.
Another of Newton's continuing interests was the area in which alchemy was evolving into chemistry. His laboratory assistant during his years at Cambridge wrote of his chemical experiments as being a major occupation of these years, and Newton's manuscripts reflect the importance he attached to this phase of his research. His Mint papers show that he made use of chemical knowledge in connection with the metallic composition of the coinage. Among the vast body of his manuscripts are notes indicating that his Chronology and Prophecy and also his alchemical work were parts of a larger design that would embrace cosmology, history, and theology in a single synthesis.
Newton died in his sleep in London on 20 March 1727. His body was buried in Westminster Abbey. Voltaire may have been present at his funeral. A bachelor, he had divested much of his estate to relatives during his last years and died intestate. His papers went to John Conduitt and Catherine Barton. After his death, Newton's hair was examined and found to contain mercury, probably resulting from his alchemical pursuits. Mercury poisoning could explain Newton's eccentricity in late life.
Sir Isaac Newton is widely recognized as one of the most influential scientists of all time. In optics, his discovery of the composition of white light integrated the phenomena of colors into the science of light and laid the foundation for modern physical optics. In mechanics, his three laws of motion, the basic principles of modern physics, resulted in the formulation of the law of universal gravitation. In mathematics, he was the original discoverer of the infinitesimal calculus. Newton’s Philosophiae Naturalis Principia Mathematica (Mathematical Principles of Natural Philosophy, 1687) was one of the most important single works in the history of modern science.
Because of the resounding impact of his work, Newton became a scientific idol, much like Albert Einstein after his theory of relativity. Many books, plays, and films focus on Newton or use Newton as a literary device. Newton's stature among scientists remains at the very top rank, as demonstrated by a 2005 survey of scientists in Britain's Royal Society (formerly headed by Newton) asking who had the greater effect on the history of science, Newton or Albert Einstein. Newton was deemed more influential.
Newton's monument can be seen in Westminster Abbey, at the north of the entrance to the choir against the choir screen, near his tomb. A statue of Isaac Newton, looking at an apple at his feet, can be seen at the Oxford University Museum of Natural History.
From 1978 until 1988, an image of Newton designed by Harry Ecclestone appeared on Series D £1 banknotes issued by the Bank of England (the last £1 notes to be issued by the Bank of England). Newton was shown on the reverse of the notes holding a book and accompanied by a telescope, a prism and a map of the Solar System.
Although born into an Anglican family, by his thirties Newton held the Christian faith that, had it been made public, would not have been considered orthodox by mainstream Christianity; in recent times he has been described as a heretic.
Newton believed that God had chosen him specifically to interpret the Bible - and concluded that the world would end no sooner than 2060. "This I mention not to assert when the time of the end shall be," he explained, "but to put a stop to the rash conjectures of fanciful men who are frequently predicting the time of the end, and by doing so bring the sacred prophesies into discredit as often as their predictions fail."
By 1672, he had started to record his theological researches in notebooks which he showed to no one and which have only recently been examined. They demonstrate an extensive knowledge of early church writings and show that in the conflict between Athanasius and Arius which defined the Creed, he took the side of Arius, the loser, who rejected the conventional view of the Trinity. Newton "recognized Christ as a divine mediator between God and man, who was subordinate to the Father who created him." He was especially interested in prophecy, but for him, "the great apostasy was trinitarianism."
In Newton's eyes, worshipping Christ as God was idolatry, to him the fundamental sin. Historian Stephen D. Snobelen says, "Isaac Newton was a heretic. But ... he never made a public declaration of his private faith - which the orthodox would have deemed extremely radical. He hid his faith so well that scholars are still unravelling his personal beliefs." Snobelen concludes that Newton was at least a Socinian sympathizer (he owned and had thoroughly read at least eight Socinian books), possibly an Arian and almost certainly an anti-trinitarian.
Although the laws of motion and universal gravitation became Newton's best-known discoveries, he warned against using them to view the Universe as a mere machine, as if akin to a great clock. He said, "Gravity explains the motions of the planets, but it cannot explain who set the planets in motion. God governs all things and knows all that is or can be done."
He believed in a rationally immanent world, but he rejected the hylozoism implicit in Leibniz and Baruch Spinoza. The ordered and dynamically informed Universe could be understood, and must be understood, by an active reason. In his correspondence, Newton claimed that in writing the Principia "I had an eye upon such Principles as might work with considering men for the belief of a Deity". He saw evidence of design in the system of the world: "Such a wonderful uniformity in the planetary system must be allowed the effect of choice". But Newton insisted that divine intervention would eventually be required to reform the system, due to the slow growth of instabilities. For this, Leibniz lampooned him: "God Almighty wants to wind up his watch from time to time: otherwise it would cease to move. He had not, it seems, sufficient foresight to make it a perpetual motion."
Newton and Robert Boyle's approach to the mechanical philosophy was promoted by rationalist pamphleteers as a viable alternative to the pantheists and enthusiasts and was accepted hesitantly by orthodox preachers as well as dissident preachers like the latitudinarians. The clarity and simplicity of science were seen as a way to combat the emotional and metaphysical superlatives of both superstitious enthusiasm and the threat of atheism, and at the same time, the second wave of English deists used Newton's discoveries to demonstrate the possibility of a "Natural Religion."
Politics
Politically and personally tied to the Whig party, Newton served two brief terms as Member of Parliament for the University of Cambridge, in 1689-90 and 1701-02. During this time, the legislative body enacted the Bill of Rights, which limited the power of the monarchy and laid out the rights of Parliament along with certain individual rights. Newton’s contributions to Parliament apparently were limited. Nevertheless, while in London Newton became acquainted with a number of influential people, from King William III to the philosopher John Locke. Newton served a second brief term in Parliament, from 1701 to 1702, and again seems to have contributed little.
Views
Newton discovered the new conception of nature that provided the framework of the scientific revolution. He had thoroughly mastered the works of Descartes and had also discovered that the French philosopher Pierre Gassendi had revived atomism, an alternative mechanical system to explain nature. The “Quaestiones” also reveal that Newton already was inclined to find the latter a more attractive philosophy than Cartesian natural philosophy, which rejected the existence of ultimate indivisible particles.
In optics, the core of Newton’s contribution had to do with colours. An ancient theory extending back at least to Aristotle held that a certain class of colour phenomena, such as the rainbow, arises from the modification of light, which appears white in its pristine form. Descartes had generalized this theory for all colours and translated it into mechanical imagery. Through a series of experiments performed in 1665 and 1666, in which the spectrum of a narrow beam was projected onto the wall of a darkened chamber, Newton denied the concept of modification and replaced it with that of analysis. Basically, he denied that light is simple and homogeneous - stating instead that it is complex and heterogeneous and that the phenomena of colours arise from the analysis of the heterogeneous mixture into its simple components. The source of Newton’s conviction that light is corpuscular was his recognition that individual rays of light have immutable properties; in his view, such properties imply immutable particles of matter. He held that individual rays (that is, particles of given size) excite sensations of individual colours when they strike the retina of the eye. He also concluded that rays refract at distinct angles - hence, the prismatic spectrum, a beam of heterogeneous rays, i.e., alike incident on one face of a prism, separated or analyzed by the refraction into its component parts - and that phenomena such as the rainbow are produced by refractive analysis. Because he believed that chromatic aberration could never be eliminated from lenses, Newton turned to reflecting telescopes; he constructed the first ever built.
Later Newton was greatly influenced by the Hermetic tradition with which he had been familiar since his undergraduate days. Newton, always somewhat interested in alchemy, now immersed himself in it, copying by hand treatise after treatise and collating them to interpret their arcane imagery. Under the influence of the Hermetic tradition, his conception of nature underwent a decisive change. Until that time, Newton had been a mechanical philosopher in the standard 17th-century style, explaining natural phenomena by the motions of particles of matter. Thus, he held that the physical reality of light is a stream of tiny corpuscles diverted from its course by the presence of denser or rarer media.
Newton’s “Hypothesis of Light” of 1675, with its universal ether, was a standard mechanical system of nature. Some phenomena, such as the capacity of chemicals to react only with certain others, puzzled him, however, and he spoke of a “secret principle” by which substances are “sociable” or “unsociable” with others. About 1679, Newton abandoned the ether and its invisible mechanisms and began to ascribe the puzzling phenomena - chemical affinities, the generation of heat in chemical reactions, surface tension in fluids, capillary action, the cohesion of bodies, and the like - to attractions and repulsions between particles of matter. More than 35 years later, in the second English edition of the Opticks, Newton accepted an ether again, although it was an ether that embodied the concept of action at a distance by positing a repulsion between its particles. The attractions and repulsions of Newton’s speculations were direct transpositions of the occult sympathies and antipathies of Hermetic philosophy - as mechanical philosophers never ceased to protest. Newton, however, regarded them as a modification of the mechanical philosophy that rendered it subject to exact mathematical treatment. As he conceived of them, attractions were quantitatively defined, and they offered a bridge to unite the two basic themes of 17th-century science - the mechanical tradition, which had dealt primarily with verbal mechanical imagery, and the Pythagorean tradition, which insisted on the mathematical nature of reality. Newton’s reconciliation through the concept of force was his ultimate contribution to science.
Newton originally applied the idea of attractions and repulsions solely to the range of terrestrial phenomena. But late in 1679, not long after he had embraced the concept, another application was suggested in a letter from Hooke, who was seeking to renew correspondence. Hooke mentioned his analysis of planetary motion - in effect, the continuous diversion of a rectilinear motion by a central attraction. Newton refused to correspond but went on to mention an experiment to demonstrate the rotation of Earth: let a body be dropped from a tower; because the tangential velocity at the top of the tower is greater than that at the foot, the body should fall slightly to the east. He sketched the path of fall as part of a spiral ending at the centre of Earth. This was a mistake, as Hooke pointed out; according to Hooke’s theory of planetary motion, the path should be elliptical, so that if Earth were split and separated to allow the body to fall, it would rise again to its original location. Newton did not like being corrected, least of all by Hooke, but he had to accept the basic point; he corrected Hooke’s figure, however, using the assumption that gravity is constant. Hooke then countered by replying that, although Newton’s figure was correct for constant gravity, his own assumption was that gravity decreases as the square of the distance. Several years later, this letter became the basis for Hooke’s charge of plagiarism. He was mistaken in the charge. His knowledge of the inverse square relation rested only on intuitive grounds; he did not derive it properly from the quantitative statement of centripetal force and Kepler’s third law, which relates the periods of planets to the radii of their orbits. Moreover, unknown to him, Newton had so derived the relation more than 10 years earlier. Nevertheless, Newton later confessed that the correspondence with Hooke led him to demonstrate that an elliptical orbit entails an inverse square attraction to one focus - one of the two crucial propositions on which the law of universal gravitation would ultimately rest.
Nearly five years later, in August 1684, Newton was visited by the British astronomer Edmond Halley, who was also troubled by the problem of orbital dynamics. Upon learning that Newton had solved the problem, he extracted Newton’s promise to send the demonstration. Three months later he received a short tract entitled De Motu (“On Motion”). Already Newton was at work improving and expanding it. In two and a half years, the tract De Motu grew into Philosophiae Naturalis Principia Mathematica, which is not only Newton’s masterpiece but also the fundamental work for the whole of modern science.
Significantly, De Motu did not state the law of universal gravitation. For that matter, even though it was a treatise on planetary dynamics, it did not contain any of the three Newtonian laws of motion. Only when revising De Motu did Newton embrace the principle of inertia (the first law) and arrive at the second law of motion. The second law, the force law, proved to be a precise quantitative statement of the action of the forces between bodies that had become the central members of his system of nature. By quantifying the concept of force, the second law completed the exact quantitative mechanics that has been the paradigm of natural science ever since.
The mechanics of the Principia was an exact quantitative description of the motions of visible bodies. It rested on Newton’s three laws of motion: (1) that a body remains in its state of rest unless it is compelled to change that state by a force impressed on it; (2) that the change of motion (the change of velocity times the mass of the body) is proportional to the force impressed; (3) that to every action there is an equal and opposite reaction. The analysis of circular motion in terms of these laws yielded a formula of the quantitative measure, in terms of a body’s velocity and mass, of the centripetal force necessary to divert a body from its rectilinear path into a given circle. When Newton substituted this formula into Kepler’s third law, he found that the centripetal force holding the planets in their given orbits about the Sun must decrease with the square of the planets’ distances from the Sun. Because the satellites of Jupiter also obey Kepler’s third law, an inverse square centripetal force must also attract them to the centre of their orbits. Newton was able to show that a similar relation holds between Earth and its Moon. The distance of the Moon is approximately 60 times the radius of Earth. Newton compared the distance by which the Moon, in its orbit of known size, is diverted from a tangential path in one second with the distance that a body at the surface of Earth falls from rest in one second. When the latter distance proved to be 3,600 (60 × 60) times as great as the former, he concluded that one and the same force, governed by a single quantitative law, is operative in all three cases, and from the correlation of the Moon’s orbit with the measured acceleration of gravity on the surface of Earth, he applied the ancient Latin word gravitas to it. The law of universal gravitation, which he also confirmed from such further phenomena as the tides and the orbits of comets, states that every particle of matter in the universe attracts every other particle with a force that is proportional to the product of their masses and inversely proportional to the square of the distance between their centres.
Quotations:
"To every action there is always opposed an equal reaction."
"Plato is my friend - Aristotle is my friend - but my greatest friend is truth."
"If I have seen further it is by standing on ye sholders of Giants."
"To explain all nature is too difficult a task for any one man or even for any one age. 'Tis much better to do a little with certainty, and leave the rest for others that come after you, than to explain all things by conjecture without making sure of any thing."
"I do not know what I may appear to the world, but to myself I seem to have been only like a boy playing on the sea-shore, and diverting myself in now and then finding a smoother pebble or a prettier shell than ordinary, whilst the great ocean of truth lay all undiscovered before me."
"In default of any other proof, the thumb would convince me of the existence of a God."
"It is the perfection of God's works that they are all done with the greatest simplicity. He is the God of order and not of confusion. "
"Truth is ever to be found in simplicity, and not in the multiplicity and confusion of things."
"God created everything by number, weight, and measure."
"Godliness consists in the knowledge love and worship of God, Humanity in love, righteousness, and good offices towards man."
"Atheism is so senseless and odious to mankind that it never had many professors."
Membership
Royal Society
1672 - 1727
Personality
The mass of Newton's papers, manuscripts, and correspondence which survives reveals a person with qualities of mind, physique, and personality extraordinarily favorable for the making of a great scientist: tremendous powers of concentration, ability to stand long periods of intense mental exertion, and objectivity uncomplicated by frivolous interests.
Newton suffered twice with a nervous breakdown. This happened when he suspected that his friends conspired against him.
Isaac Newton was sometimes a controversial and hot-tempered person. He ruled the Royal Society magisterially. John Flamsteed, the Astronomer Royal, had occasion to feel that he ruled it tyrannically. In his years at the Royal Observatory at Greenwich, Flamsteed, who was a difficult man in his own right, had collected an unrivaled body of data. Newton had received needed information from him for the Principia, and in the 1690s, as he worked on the lunar theory, he again required Flamsteed’s data. Annoyed when he could not get all the information he wanted as quickly as he wanted it, Newton assumed a domineering and condescending attitude toward Flamsteed. As president of the Royal Society, he used his influence with the government to be named as chairman of a body of “visitors” responsible for the Royal Observatory; then he tried to force the immediate publication of Flamsteed’s catalog of stars. The disgraceful episode continued for nearly 10 years. Newton would brook no objections. He broke agreements that he had made with Flamsteed. Flamsteed’s observations, the fruit of a lifetime of work, were, in effect, seized despite his protests and prepared for the press by his mortal enemy, Edmond Halley. Flamsteed finally won his point and by court order had the printed catalog returned to him before it was generally distributed. He burned the printed sheets, and his assistants brought out an authorized version after his death. In this respect, and at considerable cost to himself, Flamsteed was one of the few men to beat Newton. Newton sought his revenge by systematically eliminating references to Flamsteed’s help in later editions of the Principia.
Physical Characteristics:
The many portraits of Newton (he was painted by nearly all the leading artists of his time) range from the fashionable, somewhat idealized, treatment to a more convincing realism. All present the natural dignity, the serious mien, and the large searching eyes mentioned by his contemporaries.
Quotes from others about the person
Newton and Locke are examples of the deep sagacity which may be acquired by long habits of thinking and study." - John Adams
"Newton was not the first of the age of reason. He was the last of the magicians." - John Maynard Keynes
"Newton was the greatest genius that ever existed, and the most fortunate, for we cannot find more than once a system of the world to establish." - Joseph Louis Lagrange
"A genius is someone who discovers that the stone that falls and the moon that doesn't fall represent one and the same phenomenon." - Ernesto Sábato
"Newton did not show the cause of the apple falling, but he shewed a similitude between the apple and the stars." - D'Arcy Wentworth Thompson
Interests
Philosophers & Thinkers
Descartes, Galileo, Henry More
Connections
Newton never married and there are no credible records that he was ever involved in a romantic relationship. The French writer and philosopher Voltaire, who was in London at the time of Newton's funeral, said that he "was never sensible to any passion, was not subject to the common frailties of mankind, nor had any commerce with women - a circumstance which was assured me by the physician and surgeon who attended him in his last moments."
Father:
Isaac Newton
Newton's father, also named Isaac Newton, had died three months before his birth.
Mother:
Hannah Ayscough
Hanna Ayscough left her son in the care of his grandmother in order to marry Barnabas Smith. The abandonment by his mother may have had a traumatizing effect on young Isaac.
step-father:
Barnabas Smith
Isaac Newton felt a deep hatred for his mother's new husband.
grandmother:
Margery Ayscough
Uncle:
William Ayscough
roommate:
John Wickens
John Wickens was Newton's chamber-fellow for twenty years.
Among those with whom Isaac Newton feuded was German mathematician and philosopher Gottfried Leibniz; the two men had a bitter battle over who invented calculus. Newton developed a version of calculus in the 1660s but didn’t publish his work at the time. In the 1670s, Leibniz formulated his own version of calculus, publishing his work a decade later. Newton later charged that the German scholar had plagiarized his unpublished writings after documents summarizing it circulated through the Royal Society. Leibniz contended he’d reached his results independently and implied that Newton had stolen from his published work. In an effort to defend himself, Leibniz eventually appealed to the Royal Society and in 1712 Newton, who’d served as the organization’s president since 1703, agreed that an impartial committee would be assembled to look into the issue. Instead, he packed the committee with his supporters and even penned the group’s report, which publicly credited him with discovering calculus. Today, however, Leibniz’s system of calculus is the one commonly used.
opponent:
Robert Hooke
When Robert Hooke criticised some of Newton's ideas, Newton was so offended that he withdrew from public debate. Newton and Hooke had brief exchanges in 1679–80, when Hooke, appointed to manage the Royal Society's correspondence, opened up a correspondence intended to elicit contributions from Newton to Royal Society transactions, which had the effect of stimulating Newton to work out a proof that the elliptical form of planetary orbits would result from a centripetal force inversely proportional to the square of the radius vector. But the two men remained generally on poor terms until Hooke's death.
Samuel Clarke was Newton's friend and disciple, who helped to spread Newton’s views. He vigorously defended Newton in correspondence with Gottfried Wilhelm Leibniz.
colleague:
Edmund Halley
Edmund Halley helped Newton to publish his Philosophiæ Naturalis Principia Mathematica.
