Second is the contrast, often shocking, between the actual content of Newton's public writings and the positions attributed to him by others, including most importantly his popularizers. Third is the contrast between the enormous range of subjects to which Newton devoted his full concentration at one time or another during the 60 years of his intellectual career — mathematics, optics, mechanics, astronomy, experimental chemistry, alchemy, and theology — and the remarkably little information we have about what drove him or his sense of himself.
Biographers and analysts who try to piece together a unified picture of Newton and his intellectual endeavors often end up telling us almost as much about themselves as about Newton. Compounding the diversity of the subjects to which Newton devoted time are sharp contrasts in his work within each subject. The most important element common to these two was Newton's deep commitment to having the empirical world serve not only as the ultimate arbiter, but also as the sole basis for adopting provisional theory.
Throughout all of this work he displayed distrust of what was then known as the method of hypotheses — putting forward hypotheses that reach beyond all known phenomena and then testing them by deducing observable conclusions from them. Newton insisted instead on having specific phenomena decide each element of theory, with the goal of limiting the provisional aspect of theory as much as possible to the step of inductively generalizing from the specific phenomena.
This stance is perhaps best summarized in his fourth Rule of Reasoning, added in the third edition of the Principia , but adopted as early as his Optical Lectures of the s:.
In experimental philosophy, propositions gathered from phenomena by induction should be taken to be either exactly or very nearly true notwithstanding any contrary hypotheses, until yet other phenomena make such propositions either more exact or liable to exceptions.
This rule should be followed so that arguments based on induction may not be nullified by hypotheses. Such a commitment to empirically driven science was a hallmark of the Royal Society from its very beginnings, and one can find it in the research of Kepler, Galileo, Huygens, and in the experimental efforts of the Royal Academy of Paris.
Newton, however, carried this commitment further first by eschewing the method of hypotheses and second by displaying in his Principia and Opticks how rich a set of theoretical results can be secured through well-designed experiments and mathematical theory designed to allow inferences from phenomena.
The success of those after him in building on these theoretical results completed the process of transforming natural philosophy into modern empirical science. Newton's commitment to having phenomena decide the elements of theory required questions to be left open when no available phenomena could decide them. Newton contrasted himself most strongly with Leibniz in this regard at the end of his anonymous review of the Royal Society's report on the priority dispute over the calculus:.
Newton could have said much the same about the question of what light consists of, waves or particles, for while he felt that the latter was far more probable, he saw it still not decided by any experiment or phenomenon in his lifetime.
Leaving questions about the ultimate cause of gravity and the constitution of light open was the other factor in his work driving a wedge between natural philosophy and empirical science. The many other areas of Newton's intellectual endeavors made less of a difference to eighteenth century philosophy and science. In mathematics, Newton was the first to develop a full range of algorithms for symbolically determining what we now call integrals and derivatives, but he subsequently became fundamentally opposed to the idea, championed by Leibniz, of transforming mathematics into a discipline grounded in symbol manipulation.
Newton thought the only way of rendering limits rigorous lay in extending geometry to incorporate them, a view that went entirely against the tide in the development of mathematics in the eighteenth and nineteenth ceturies. In chemistry Newton conducted a vast array of experiments, but the experimental tradition coming out of his Opticks , and not his experiments in chemistry, lay behind Lavoisier calling himself a Newtonian; indeed, one must wonder whether Lavoisier would even have associated his new form of chemistry with Newton had he been aware of Newton's fascination with writings in the alchemical tradition.
And even in theology, there is Newton the anti-Trinitarian mild heretic who was not that much more radical in his departures from Roman and Anglican Christianity than many others at the time, and Newton, the wild religious zealot predicting the end of the Earth, who did not emerge to public view until quite recently.
There is surprisingly little cross-referencing of themes from one area of Newton's endeavors to another. The common element across almost all of them is that of a problem-solver extraordinaire , taking on one problem at a time and staying with it until he had found, usually rather promptly, a solution. All of his technical writings display this, but so too does his unpublished manuscript reconstructing Solomon's Temple from the biblical account of it and his posthumously published Chronology of the Ancient Kingdoms in which he attempted to infer from astronomical phenomena the dating of major events in the Old Testament.
The Newton one encounters in his writings seems to compartmentalize his interests at any given moment. Whether he had a unified conception of what he was up to in all his intellectual efforts, and if so what this conception might be, has been a continuing source of controversy among Newton scholars. Of course, were it not for the Principia , there would be no entry at all for Newton in an Encyclopedia of Philosophy. In science, he would have been known only for the contributions he made to optics, which, while notable, were no more so than those made by Huygens and Grimaldi, neither of whom had much impact on philosophy; and in mathematics, his failure to publish would have relegated his work to not much more than a footnote to the achievements of Leibniz and his school.
But this adds still a further complication, for the Principia itself was substantially different things to different people. The press-run of the first edition estimated to be around was too small for it to have been read by all that many individuals.
The second edition also appeared in two pirated Amsterdam editions, and hence was much more widely available, as was the third edition and its English and later French translation. The Principia , however, is not an easy book to read, so one must still ask, even of those who had access to it, whether they read all or only portions of the book and to what extent they grasped the full complexity of what they read.
The detailed commentary provided in the three volume Jesuit edition —42 made the work less daunting. An important question to ask of any philosophers commenting on Newton is, what primary sources had they read? The s witnessed a major transformation in the standing of the science in the Principia. The Principia itself had left a number of loose-ends, most of them detectable by only highly discerning readers.
By , however, some of these loose-ends had been cited in Bernard le Bovier de Fontenelle's elogium for Newton [ 4 ] and in John Machin's appendix to the English translation of the Principia , raising questions about just how secure Newton's theory of gravity was, empirically. The shift on the continent began in the s when Maupertuis convinced the Royal Academy to conduct expeditions to Lapland and Peru to determine whether Newton's claims about the non-spherical shape of the Earth and the variation of surface gravity with latitude are correct.
Euler was the central figure in turning the three laws of motion put forward by Newton in the Principia into Newtonian mechanics. Most of the effort of eighteenth century mechanics was devoted to solving problems of the motion of rigid bodies, elastic strings and bodies, and fluids, all of which require principles beyond Newton's three laws. From the s on this led to alternative approaches to formulating a general mechanics, employing such different principles as the conservation of vis viva , the principle of least action, and d'Alembert's principle.
During the s Euler developed his equations for the motion of fluids, and in the s, his equations of rigid-body motion. What we call Newtonian mechanics was accordingly something for which Euler was more responsible than Newton. Although some loose-ends continued to defy resolution until much later in the eighteenth century, by the early s Newton's theory of gravity had become the accepted basis for ongoing research among almost everyone working in orbital astronomy.
Clairaut's successful prediction of the month of return of Halley's comet at the end of this decade made a larger segment of the educated public aware of the extent to which empirical grounds for doubting Newton's theory of gravity had largely disappeared.
Even so, one must still ask of anyone outside active research in gravitational astronomy just how aware they were of the developments from ongoing efforts when they made their various pronouncements about the standing of the science of the Principia among the community of researchers. The naivety of these pronouncements cuts both ways: on the one hand, they often reflected a bloated view of how secure Newton's theory was at the time, and, on the other, they often underestimated how strong the evidence favoring it had become.
The upshot is a need to be attentive to the question of what anyone, even including Newton himself, had in mind when they spoke of the science of the Principia. To view the seventy years of research after Newton died as merely tying up the loose-ends of the Principia or as simply compiling more evidence for his theory of gravity is to miss the whole point.
However, Newton never seemed to understand the notion of science as a cooperative venture, and his ambition and fierce defense of his own discoveries continued to lead him from one conflict to another with other scientists. By most accounts, Newton's tenure at the society was tyrannical and autocratic; he was able to control the lives and careers of younger scientists with absolute power.
In , in a controversy that had been brewing for several years, German mathematician Gottfried Leibniz publicly accused Newton of plagiarizing his research, claiming he had discovered infinitesimal calculus several years before the publication of Principia. In , the Royal Society appointed a committee to investigate the matter. Of course, since Newton was president of the society, he was able to appoint the committee's members and oversee its investigation.
Not surprisingly, the committee concluded Newton's priority over the discovery. That same year, in another of Newton's more flagrant episodes of tyranny, he published without permission the notes of astronomer John Flamsteed. It seems the astronomer had collected a massive body of data from his years at the Royal Observatory at Greenwich, England.
Newton had requested a large volume of Flamsteed's notes for his revisions to Principia. Annoyed when Flamsteed wouldn't provide him with more information as quickly as he wanted it, Newton used his influence as president of the Royal Society to be named the chairman of the body of "visitors" responsible for the Royal Observatory. He then tried to force the immediate publication of Flamsteed's catalogue of the stars, as well as all of Flamsteed's notes, edited and unedited. To add insult to injury, Newton arranged for Flamsteed's mortal enemy, Edmund Halley, to prepare the notes for press.
Flamsteed was finally able to get a court order forcing Newton to cease his plans for publication and return the notes—one of the few times that Newton was bested by one of his rivals. By this time, Newton had become one of the most famous men in Europe.
His scientific discoveries were unchallenged. He also had become wealthy, investing his sizable income wisely and bestowing sizable gifts to charity. Despite his fame, Newton's life was far from perfect: He never married or made many friends, and in his later years, a combination of pride, insecurity and side trips on peculiar scientific inquiries led even some of his few friends to worry about his mental stability.
By the time he reached 80 years of age, Newton was experiencing digestion problems and had to drastically change his diet and mobility. In March , Newton experienced severe pain in his abdomen and blacked out, never to regain consciousness. He died the next day, on March 31, , at the age of Newton's fame grew even more after his death, as many of his contemporaries proclaimed him the greatest genius who ever lived. Maybe a slight exaggeration, but his discoveries had a large impact on Western thought, leading to comparisons to the likes of Plato , Aristotle and Galileo.
Although his discoveries were among many made during the Scientific Revolution, Newton's universal principles of gravity found no parallels in science at the time. Of course, Newton was proven wrong on some of his key assumptions.
In the 20th century, Albert Einstein would overturn Newton's concept of the universe, stating that space, distance and motion were not absolute but relative and that the universe was more fantastic than Newton had ever conceived. Newton might not have been surprised: In his later life, when asked for an assessment of his achievements, he replied, "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 seashore, and diverting myself now and then in finding a smoother pebble or prettier shell than ordinary, while the great ocean of truth lay all undiscovered before me.
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Singer-songwriter and actress Olivia Newton-John, known for playing Sandy in the musical film 'Grease,' has battled breast cancer and helped raise awareness through her music. James C. Shortly after his election to the Royal Society in , Newton published his first paper in the Philosophical Transactions of the Royal Society.
This paper, and others that followed, drew on his undergraduate researches as well as his Lucasian lectures at Cambridge. I n , Newton performed a number of experiments on the composition of light. Guided initially by the writings of Kepler and Descartes, Newton's main discovery was that visible white light is heterogeneous--that is, white light is composed of colors that can be considered primary.
Through a brilliant series of experiments, Newton demonstrated that prisms separate rather than modify white light. Contrary to the theories of Aristotle and other ancients, Newton held that white light is secondary and heterogeneous, while the separate colors are primary and homogeneous.
Of perhaps equal importance, Newton also demonstrated that the colors of the spectrum, once thought to be qualities, correspond to an observed and quantifiable 'degree of Refrangibility.
N ewton's most famous experiment, the experimentum crucis , demonstrated his theory of the composition of light. Briefly, in a dark room Newton allowed a narrow beam of sunlight to pass from a small hole in a window shutter through a prism, thus breaking the white light into an oblong spectrum on a board.
Then, through a small aperture in the board, Newton selected a given color for example, red to pass through yet another aperture to a second prism, through which it was refracted onto a second board. What began as ordinary white light was thus dispersed through two prisms. N ewton's 'crucial experiment' demonstrated that a selected color leaving the first prism could not be separated further by the second prism. The selected beam remained the same color, and its angle of refraction was constant throughout.
Newton concluded that white light is a 'Heterogeneous mixture of differently refrangible Rays' and that colors of the spectrum cannot themselves be individually modified, but are 'Original and connate properties. His Lucasian lectures, later published in part as Optical Lectures , supplement other researches published in the Society's Transactions dating from February The Opticks. T he Opticks of , which first appeared in English, is Newton's most comprehensive and readily accessible work on light and color.
In Newton's words, the purpose of the Opticks was 'not to explain the Properties of Light by Hypotheses, but to propose and prove them by Reason and Experiments. A subtle blend of mathematical reasoning and careful observation, the Opticks became the model for experimental physics in the 18th century. The Corpuscular Theory. B ut the Opticks contained more than experimental results.
During the 17th century it was widely held that light, like sound, consisted of a wave or undulatory motion, and Newton's major critics in the field of optics--Robert Hooke and Christiaan Huygens--were articulate spokesmen for this theory.
But Newton disagreed. Although his views evolved over time, Newton's theory of light was essentially corpuscular, or particulate. In effect, since light unlike sound travels in straight lines and casts a sharp shadow, Newton suggested that light was composed of discrete particles moving in straight lines in the manner of inertial bodies.
Further, since experiment had shown that the properties of the separate colors of light were constant and unchanging, so too, Newton reasoned, was the stuff of light itself-- particles. A t various points in his career Newton in effect combined the particle and wave theories of light.
In his earliest dispute with Hooke and again in his Opticks of , Newton considered the possibility of an ethereal substance--an all-pervasive elastic material more subtle than air--that would provide a medium for the propagation of waves or vibrations. From the outset Newton rejected the basic wave models of Hooke and Huygens, perhaps because they overlooked the subtlety of periodicity.
T he question of periodicity arose with the phenomenon known as 'Newton's rings. His most remarkable observation was that light passing through a convex lens pressed against a flat glass plate produces concentric colored rings Newton's rings with alternating dark rings. Newton attempted to explain this phenomenon by employing the particle theory in conjunction with his hypothesis of 'fits of easy transmission [refraction] and reflection.
If dark rings occurred at thicknesses of 0, 2, 4, Although Newton did not speculate on the cause of this periodicity, his initial association of 'Newton's rings' with vibrations in a medium suggests his willingness to modify but not abandon the particle theory.
T he Opticks was Newton's most widely read work. Following the first edition, Latin versions appeared in and , and second and third English editions in and Perhaps the most provocative part of the Opticks is the section known as the 'Queries,' which Newton placed at the end of the book. Here he posed questions and ventured opinions on the nature of light, matter, and the forces of nature. Newton's research in dynamics falls into three major periods: the plague years , the investigations of , following Hooke's correspondence, and the period , following Halley's visit to Cambridge.
The gradual evolution of Newton's thought over these two decades illustrates the complexity of his achievement as well as the prolonged character of scientific 'discovery. To be sure, Newton's early thoughts on gravity began in Woolsthorpe, but at the time of his famous 'moon test' Newton had yet to arrive at the concept of gravitational attraction.
Early manuscripts suggest that in the mid's, Newton did not think in terms of the moon's central attraction toward the earth but rather of the moon's centrifugal tendency to recede. Under the influence of the mechanical philosophy, Newton had yet to consider the possibility of action- at-a-distance; nor was he aware of Kepler's first two planetary hypotheses. For historical, philosophical, and mathematical reasons, Newton assumed the moon's centrifugal 'endeavour' to be equal and opposite to some unknown mechanical constraint.
For the same reasons, he also assumed a circular orbit and an inverse square relation. The latter was derived from Kepler's third hypothesis the square of a planet's orbital period is proportional to the cube of its mean distance from the sun , the formula for centrifugal force the centrifugal force on a revolving body is proportional to the square of its velocity and inversely proportional to the radius of its orbit , and the assumption of circular orbits.
T he next step was to test the inverse square relation against empirical data. To do this Newton, in effect, compared the restraint on the moon's 'endeavour' to recede with the observed rate of acceleration of falling objects on earth.
The problem was to obtain accurate data. As Newton later described it, the moon test answered 'pretty nearly. However he seems to have shown little promise in academic work. His school reports described him as 'idle' and 'inattentive'. His mother, by now a lady of reasonable wealth and property, thought that her eldest son was the right person to manage her affairs and her estate. Isaac was taken away from school but soon showed that he had no talent, or interest, in managing an estate.
An uncle, William Ayscough, decided that Isaac should prepare for entering university and, having persuaded his mother that this was the right thing to do, Isaac was allowed to return to the Free Grammar School in Grantham in to complete his school education. This time he lodged with Stokes, who was the headmaster of the school, and it would appear that, despite suggestions that he had previously shown no academic promise, Isaac must have convinced some of those around him that he had academic promise.
Some evidence points to Stokes also persuading Isaac's mother to let him enter university, so it is likely that Isaac had shown more promise in his first spell at the school than the school reports suggest. Another piece of evidence comes from Isaac's list of sins referred to above. He lists one of his sins as We know nothing about what Isaac learnt in preparation for university, but Stokes was an able man and almost certainly gave Isaac private coaching and a good grounding.
There is no evidence that he learnt any mathematics, but we cannot rule out Stokes introducing him to Euclid 's Elements which he was well capable of teaching although there is evidence mentioned below that Newton did not read Euclid before Anecdotes abound about a mechanical ability which Isaac displayed at the school and stories are told of his skill in making models of machines, in particular of clocks and windmills. However, when biographers seek information about famous people there is always a tendency for people to report what they think is expected of them, and these anecdotes may simply be made up later by those who felt that the most famous scientist in the world ought to have had these skills at school.
He was older than most of his fellow students but, despite the fact that his mother was financially well off, he entered as a sizar. A sizar at Cambridge was a student who received an allowance toward college expenses in exchange for acting as a servant to other students.
There is certainly some ambiguity in his position as a sizar, for he seems to have associated with "better class" students rather than other sizars. Westfall see [ 23 ] or [ 24 ] has suggested that Newton may have had Humphrey Babington, a distant relative who was a Fellow of Trinity, as his patron. This reasonable explanation would fit well with what is known and mean that his mother did not subject him unnecessarily to hardship as some of his biographers claim.
Newton's aim at Cambridge was a law degree. Instruction at Cambridge was dominated by the philosophy of Aristotle but some freedom of study was allowed in the third year of the course. Newton studied the philosophy of Descartes , Gassendi , Hobbes , and in particular Boyle.
The mechanics of the Copernican astronomy of Galileo attracted him and he also studied Kepler 's Optics. It is a fascinating account of how Newton's ideas were already forming around He headed the text with a Latin statement meaning " Plato is my friend, Aristotle is my friend, but my best friend is truth" showing himself a free thinker from an early stage. How Newton was introduced to the most advanced mathematical texts of his day is slightly less clear. According to de Moivre , Newton's interest in mathematics began in the autumn of when he bought an astrology book at a fair in Cambridge and found that he could not understand the mathematics in it.
Attempting to read a trigonometry book, he found that he lacked knowledge of geometry and so decided to read Barrow 's edition of Euclid 's Elements. The first few results were so easy that he almost gave up but he Returning to the beginning, Newton read the whole book with a new respect.
Newton also studied Wallis 's Algebra and it appears that his first original mathematical work came from his study of this text. He read Wallis 's method for finding a square of equal area to a parabola and a hyperbola which used indivisibles. Newton made notes on Wallis 's treatment of series but also devised his own proofs of the theorems writing:- Thus Wallis doth it, but it may be done thus It would be easy to think that Newton's talent began to emerge on the arrival of Barrow to the Lucasian chair at Cambridge in when he became a Fellow at Trinity College.
Certainly the date matches the beginnings of Newton's deep mathematical studies. However, it would appear that the date is merely a coincidence and that it was only some years later that Barrow recognised the mathematical genius among his students. Despite some evidence that his progress had not been particularly good, Newton was elected a scholar on 28 April and received his bachelor's degree in April It would appear that his scientific genius had still not emerged, but it did so suddenly when the plague closed the University in the summer of and he had to return to Lincolnshire.
There, in a period of less than two years, while Newton was still under 25 years old, he began revolutionary advances in mathematics, optics, physics, and astronomy. While Newton remained at home he laid the foundations for differential and integral calculus, several years before its independent discovery by Leibniz. The 'method of fluxions', as he termed it, was based on his crucial insight that the integration of a function is merely the inverse procedure to differentiating it.
Taking differentiation as the basic operation, Newton produced simple analytical methods that unified many separate techniques previously developed to solve apparently unrelated problems such as finding areas, tangents , the lengths of curves and the maxima and minima of functions. When the University of Cambridge reopened after the plague in , Newton put himself forward as a candidate for a fellowship. In October he was elected to a minor fellowship at Trinity College but, after being awarded his Master's Degree, he was elected to a major fellowship in July which allowed him to dine at the Fellows' Table.
In July Barrow tried to ensure that Newton's mathematical achievements became known to the world. He sent Newton's text De Analysi to Collins in London writing:- [ Newton ] brought me the other day some papers, wherein he set down methods of calculating the dimensions of magnitudes like that of Mr Mercator concerning the hyperbola, but very general; as also of resolving equations; which I suppose will please you; and I shall send you them by the next.
Collins corresponded with all the leading mathematicians of the day so Barrow 's action should have led to quick recognition. Collins showed Brouncker , the President of the Royal Society , Newton's results with the author's permission but after this Newton requested that his manuscript be returned. Collins could not give a detailed account but de Sluze and Gregory learnt something of Newton's work through Collins.
Barrow resigned the Lucasian chair in to devote himself to divinity, recommending that Newton still only 27 years old be appointed in his place. Shortly after this Newton visited London and twice met with Collins but, as he wrote to Gregory Newton's first work as Lucasian Professor was on optics and this was the topic of his first lecture course begun in January He had reached the conclusion during the two plague years that white light is not a simple entity.
Every scientist since Aristotle had believed that white light was a basic single entity, but the chromatic aberration in a telescope lens convinced Newton otherwise. When he passed a thin beam of sunlight through a glass prism Newton noted the spectrum of colours that was formed. He argued that white light is really a mixture of many different types of rays which are refracted at slightly different angles, and that each different type of ray produces a different spectral colour.
Newton was led by this reasoning to the erroneous conclusion that telescopes using refracting lenses would always suffer chromatic aberration. He therefore proposed and constructed a reflecting telescope.
In Newton was elected a fellow of the Royal Society after donating a reflecting telescope. Also in Newton published his first scientific paper on light and colour in the Philosophical Transactions of the Royal Society. The paper was generally well received but Hooke and Huygens objected to Newton's attempt to prove, by experiment alone, that light consists of the motion of small particles rather than waves.
The reception that his publication received did nothing to improve Newton's attitude to making his results known to the world. He was always pulled in two directions, there was something in his nature which wanted fame and recognition yet another side of him feared criticism and the easiest way to avoid being criticised was to publish nothing.
Certainly one could say that his reaction to criticism was irrational, and certainly his aim to humiliate Hooke in public because of his opinions was abnormal. However, perhaps because of Newton's already high reputation, his corpuscular theory reigned until the wave theory was revived in the 19 th century.
Newton's relations with Hooke deteriorated further when, in , Hooke claimed that Newton had stolen some of his optical results. Although the two men made their peace with an exchange of polite letters, Newton turned in on himself and away from the Royal Society which he associated with Hooke as one of its leaders.
He delayed the publication of a full account of his optical researches until after the death of Hooke in Newton's Opticks appeared in It dealt with the theory of light and colour and with investigations of the colours of thin sheets 'Newton's rings' and diffraction of light.
To explain some of his observations he had to use a wave theory of light in conjunction with his corpuscular theory. His mother died in the following year and he withdrew further into his shell, mixing as little as possible with people for a number of years.
Newton's greatest achievement was his work in physics and celestial mechanics, which culminated in the theory of universal gravitation. By Newton had early versions of his three laws of motion. He had also discovered the law giving the centrifugal force on a body moving uniformly in a circular path. However he did not have a correct understanding of the mechanics of circular motion.
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