BBC - iWonder - Isaac Newton: The man who discovered gravity Isaac Newton: The man who discovered gravity 25 December 1642 20th March 1727Newton dies A genius with dark secrets Isaac Newton changed the way we understand the Universe. Revered in his own lifetime, he discovered the laws of gravity and motion and invented calculus. He helped to shape our rational world view. But Newton’s story is also one of a monstrous ego who believed that he alone was able to understand God’s creation. His private life was far from rational – consumed by petty jealousies, bitter rivalries and a ruthless quest for reputation. 25 December 1642 Not expected to survive the day You need to have JavaScript enabled to view this clip. How Newton’s early years marked him for life. Clip from Isaac Newton: The Last Magician (BBC Two). Newton was born prematurely on Christmas morning, in Woolsthorpe, Lincolnshire. He was a tiny baby, given little chance of survival. The country he was born into was chaotic and turbulent. England was being torn apart by civil war. Plague was an ever-present threat. Many believed the end of the world was imminent.

But the hamlet of Woolsthorpe was a quiet community, little touched by either war or plague, which respected Puritan values of sobriety, simple worship and hard work. A lonely boy who hated his stepfather Newton's childhood home of Woolsthorpe Manor, Lincolnshire. Newton’s father had died before he was born. When Isaac was three, his mother left him with his grandmother and married a man from a nearby village. This turbulent start scarred Newton for life. He felt rejected by his family. He hated his stepfather and threatened to burn his house down. At Grantham school, Newton sought solace in books. He was unmoved by literature and poetry but loved mechanics and technology, inventing an elaborate system of sundials which was accurate to the minute. While his mother hoped he would run the family farm, his uncle and his headmaster realised Newton was destined for an intellectual life. Making pies on Sunday night... punching my sister... threatening my Father and Mother Smith to burn them and the house over them. Newton's college notebooks contained a list of childhood sins, written in code 1661 A mathematical mentor You need to have JavaScript enabled to view this clip.

What did Newton’s professors teach him – and why did he reject it? Clip from Isaac Newton: The Last Magician (BBC Two). Newton enrolled at Trinity College, Cambridge. Here he found a father figure who set him on the road to important discoveries. Isaac Barrow, Cambridge's first professor of mathematics, steered Newton away from the standard undergraduate texts and towards the big unsolved mathematical problems of the day, such as calculus - a way of describing how things change. Calculus would later be crucial for explaining the universe in mathematical terms. Newton also hunted out new works by men such as Descartes, who argued that the Universe was governed by mechanical laws. Plato is my friend, Aristotle is my friend, but my best friend is truth. Entry in Newton’s notebook, begun in 1664 1665 Newton’s productive plague years You need to have JavaScript enabled to view this clip. See some of the remarkable ideas Newton conceived during this period of isolation. Clip from Isaac Newton: The Last Magician (BBC Two). When Cambridge University was closed because of the plague, Newton was forced to return home. This was the most productive period of his life.

Newton was driven by the belief that the path to true knowledge lay in making observations rather than reading books. For example, rather than trust texts on optics, he experimented by sticking a bodkin – a blunt needle – in his eye to see its effect. He laid the groundwork for his theories of calculus and laws of motion that would later make him famous. But, naturally secretive, he kept his ideas to himself. New ideas lead to a revolutionary new telescope You need to have JavaScript enabled to view this clip. Watch this clip to find out how Newton's telescope works. Clip from Isaac Newton: The Last Magician (BBC Two). Newton continued to experiment in his laboratory. This mix of theory and practice led him to many different kinds of discoveries. His theory of optics made him reconsider the design of the telescope, which up until this point was a large, cumbersome instrument. By using mirrors instead of lenses, Newton was able to create a more powerful instrument, 10 times smaller than traditional telescopes. When the Royal Society heard about Newton’s telescope they were impressed. This gave Newton the courage to tell them what he described as a ‘crucial experiment’ about light and colours. 1672 Taking criticism badly The Royal Society met at Crane Court.

It was a newly formed organisation for men of learning to discuss their ideas. The Royal Society was an elite group who met to share and critique each other’s work. They encouraged Newton to share his ideas. But Newton's theories about light did not go down well. Other members of the Royal Society could not reproduce his results – partly because Newton had described his experiment in an obscure manner. Newton did not take the criticism well. When Robert Hooke challenged Newton’s letters on light and colours, he made a lifelong enemy. Newton had an ugly temper and an unshakable conviction that he was right. With his pride dented, he began to withdraw from intellectual life. I believe you would think him a man of strange and unsociable temper. Newton describes Robert Hooke. Their feud often sank to the level of personal attacks 1679 A self-imposed exile In the 17th Century, alchemists searched for the philosopher’s stone and the elixir of life, and attempted to turn ordinary metals into gold. Smarting from criticism, Newton isolated himself from other natural philosophers and dedicated himself to radical religious and alchemical work.

With his mother on her deathbed, he returned home to Woolsthorpe and embarked on a period of solitary study. He became absorbed in alchemy, a secretive study of the nature of life and the medieval forerunner of chemistry. Some argue that these ideas, while not scientific in the sense that we understand them now, helped him think radical thoughts that shaped his most important work, including his theories of gravity. 1684 Newton's greatest rivalry begins Gottfried Leibniz was one of the leading philosophers in Europe and quickly made an enemy in Newton. When German philosopher Gottfried Leibniz published an important mathematical paper, it was the beginning of a lifelong feud between the two men. Leibniz, one of Europe’s most prominent philosophers, had set his mind to one of the trickiest problems in mathematics – the way equations could describe the physical world. Like Newton, he created a new theory of calculus. However, Newton claimed he'd done the same work 20 years before and that Leibniz had stolen his ideas. But the secretive Newton hadn't published his work and had to hastily return to his old notes so the world could see his workings . In a young and suddenly fertile field like Mathematics...

discoveries had lain waiting to be found again and again by different people. Newton's biographer James Gleick describes the world of the 17th Century. 1687 The Principia Mathematica: A foundation of modern science You need to have JavaScript enabled to view this clip. Find out the reaction to the publication of Newton’s Principia. Clip from Isaac Newton: The Last Magician, (BBC Two). Challenged by Robert Hooke to prove his theories about planetary orbits, Newton produced what is considered the foundation for physics as we know it. The Philosophiae Naturalis Principia Mathematica took Newton two years to write. It was the culmination of more than 20 years of thinking. It outlined his own theory of calculus, the three laws of motion and the first rigorous account of his theory of universal gravitation. Together, this provided a revolutionary new mathematical description of the Universe. The work cemented his reputation and contains much of what he is remembered for today. 1689 Newton enters the world of politics The coronation of James II at Westminster Hall: Newton fought the new king over religious reforms at Cambridge University. Having made his name as a natural philosopher, Newton was attracted to a new life as a politician and public figure.

Profoundly religious, Newton could not sit by while James II attempted to re-Catholicise Cambridge University – even if it meant nailing his own religious colours to the mast. He successfully fought James's reforms and got himself elected as a Member of Parliament. However, he made little impact in the Commons and appears on record only to ask for a window to be closed. 1693 Exhaustion and breakdown Somewhere around his 50th birthday, Newton suffered what we would now term a severe nervous breakdown. In mid-1693, Newton suffered a mental collapse when he suspected that his friends were conspiring against him. After working five nights in a row, Newton suffered what we might describe as a nervous breakdown. He later apologised to the philosopher John Locke and to the MP Samuel Pepys for having wished them dead, though whether he actually wished this is unclear. Yet Newton's fragile mental health did not dent his public reputation. He was soon offered an important new post. 1696 Newton saves Britain's currency In the 18th Century, the Royal Mint was located within the Tower of London. Newton was master for nearly 30 years. As warden of the Royal Mint, Newton found a new calling.

He attempted to make Britain's currency the most stable in the world. In the 17th Century, Britain's finances were in crisis. One in every 10 coins was forged, and often the metal in a coin was worth more than the face value of the coin itself. Newton oversaw a huge project to recall the old currency, and issue a more reliable one. Always methodical, Newton kept a database of counterfeiters, and prosecuted them with a puritanical fury. He was appointed Master of the Mint in 1700 and held the post for the rest of his life. By fire, by water, by touch or by weight, or by all or by any of them. Newton's minted coins were subject to rigorous tests to ensure their purity 1703 Newton elected president of the Royal Society You need to have JavaScript enabled to view this clip. How did Newton use his power to cement his reputation? Clip from Isaac Newton: The Last Magician, (BBC Two). As the leading figure in British natural philosophy, Newton had completed his most important work. Now he set about securing his reputation. Newton was an imposing leader, obsessed by power and reputation.

Though he continued to publish his own work, he also worked to make and break the reputations of other men. He tried to write Hooke out of history and began another bitter dispute with astronomer John Flamsteed by publishing Flamsteed's catalogue of stars without his consent. Newton remained an influential figure, surrounded by a new generation of students brought up on his ideas. If I have seen further it is by standing on the shoulders of giants. Isaac Newton's famous quote may have been a dig at his rather short rival, Hooke 1712 Newton re-writes history in his favour Newton (left) and Leibniz (right) were lifelong enemies. Newton and Leibniz had quarrelled over who invented calculus. Now Newton saw a way to triumph over his intellectual nemesis. In 1713, the Royal Society formed a committee to decide once and for all who invented calculus. It found that Newton had beaten Leibniz by many years. However, the secret author of the Royal Society report was none other than Newton himself. Leibniz refused to concede defeat, and the feud only ended once both men were dead. Today, it is accepted that both men arrived at the calculus independently.

I seem to have been only like a boy… finding a smoother pebble or a prettier shell than ordinary whilst the great ocean of truth lay all undiscovered. Remark attributed to Newton shortly before his death 1726 Newton creates a legend The story of the falling apple has became part of the mythology that surrounds Newton, as Robert Hannah's 19th Century portrait shows. At the very end of his life, Newton told a story which has become one of the most enduring legends in the history of science. Dining with fellow Royal Society member William Stukeley, Newton remembered that he had been sitting beneath an apple tree at his family home of Woolsthorpe, and a falling apple had prompted him to think about gravity. The story was also told by other people who knew Newton, including his niece Catherine who cared for him in his later years. However, the myth that Newton was hit on the head by the apple was a later invention. Newton cleverly honed this anecdote over time. The story was certainly true, but let's say it got better with the telling.

Keith Moore, head of archives at the Royal Society, on the legend of Newton and the apple 20th March 1727 Newton dies "Here lies that which was mortal of Isaac Newton": the Newton memorial at Westminster Abbey. Newton died aged 84, and was buried with full honours in Westminster Abbey. As a celebrated natural philosopher, he was a new kind of national hero. Newton laid the foundations for our scientific age. His laws of motion and theory of gravity underpin much of modern physics and engineering. Yet he had believed he was put on Earth to decode the word of God, by studying both the scriptures and the book of nature. For him, theology and mathematics were part of one project to discover a single system of the world. Newton biography Version for printing Isaac Newton's life can be divided into three quite distinct periods. The first is his boyhood days from 1643 up to his appointment to a chair in 1669. The second period from 1669 to 1687 was the highly productive period in which he was Lucasian professor at Cambridge.

The third period (nearly as long as the other two combined) saw Newton as a highly paid government official in London with little further interest in mathematical research. Isaac Newton was born in the manor house of Woolsthorpe, near Grantham in Lincolnshire. Although by the calendar in use at the time of his birth he was born on Christmas Day 1642, we give the date of 4 January 1643 in this biography which is the "corrected" Gregorian calendar date bringing it into line with our present calendar. (The Gregorian calendar was not adopted in England until 1752.) Isaac Newton came from a family of farmers but never knew his father, also named Isaac Newton, who died in October 1642, three months before his son was born. Although Isaac's father owned property and animals which made him quite a wealthy man, he was completely uneducated and could not sign his own name. You can see a picture of Woolsthorpe Manor as it is now at THIS LINK . Isaac's mother Hannah Ayscough remarried Barnabas Smith the minister of the church at North Witham, a nearby village, when Isaac was two years old.

The young child was then left in the care of his grandmother Margery Ayscough at Woolsthorpe. Basically treated as an orphan, Isaac did not have a happy childhood. His grandfather James Ayscough was never mentioned by Isaac in later life and the fact that James left nothing to Isaac in his will, made when the boy was ten years old, suggests that there was no love lost between the two. There is no doubt that Isaac felt very bitter towards his mother and his step-father Barnabas Smith. When examining his sins at age nineteen, Isaac listed:- Threatening my father and mother Smith to burn them and the house over them. Upon the death of his stepfather in 1653, Newton lived in an extended family consisting of his mother, his grandmother, one half-brother, and two half-sisters. From shortly after this time Isaac began attending the Free Grammar School in Grantham. Although this was only five miles from his home, Isaac lodged with the Clark family at Grantham. 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 1660 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:- ... setting my heart on money, learning, and pleasure more than Thee ... which tells us that Isaac must have had a passion for learning.

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 1663). 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. Newton entered his uncle's old College, Trinity College Cambridge, on 5 June 1661. 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. He recorded his thoughts in a book which he entitled Quaestiones Quaedam Philosophicae Ⓣ . It is a fascinating account of how Newton's ideas were already forming around 1664.

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 1663 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:- ... changed his mind when he read that parallelograms upon the same base and between the same parallels are equal. Returning to the beginning, Newton read the whole book with a new respect. He then turned to Oughtred 's Clavis Mathematica Ⓣ and Descartes ' La Géométrie Ⓣ . The new algebra and analytical geometry of Viète was read by Newton from Frans van Schooten 's edition of Viète 's collected works published in 1646.

Other major works of mathematics which he studied around this time was the newly published major work by van Schooten Geometria a Renato Des Cartes Ⓣ which appeared in two volumes in 1659-1661. The book contained important appendices by three of van Schooten 's disciples, Jan de Witt , Johan Hudde , and Hendrick van Heuraet . 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 1663 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 1663 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 1664 and received his bachelor's degree in April 1665. 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 1665 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. Newton's De Methodis Serierum et Fluxionum Ⓣ was written in 1671 but Newton failed to get it published and it did not appear in print until John Colson produced an English translation in 1736. When the University of Cambridge reopened after the plague in 1667, 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 1668 which allowed him to dine at the Fellows' Table. In July 1669 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 1669 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 :- ... having no more acquaintance with him I did not think it becoming to urge him to communicate anything.

Newton's first work as Lucasian Professor was on optics and this was the topic of his first lecture course begun in January 1670. 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 1672 Newton was elected a fellow of the Royal Society after donating a reflecting telescope. Also in 1672 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 19th century. Newton's relations with Hooke deteriorated further when, in 1675, 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 1703.

Newton's Opticks appeared in 1704. 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. Another argument, this time with the English Jesuits in Liège over his theory of colour, led to a violent exchange of letters, then in 1678 Newton appears to have suffered a nervous breakdown. 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 1666 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. Newton's novel idea of 1666 was to imagine that the Earth's gravity influenced the Moon, counter- balancing its centrifugal force.

From his law of centrifugal force and Kepler 's third law of planetary motion, Newton deduced the inverse-square law. In 1679 Newton corresponded with Hooke who had written to Newton claiming:- ... that the Attraction always is in a duplicate proportion to the Distance from the Center Reciprocall ... M Nauenberg writes an account of the next events:- After his 1679 correspondence with Hooke , Newton, by his own account, found a proof that Kepler's areal law was a consequence of centripetal forces, and he also showed that if the orbital curve is an ellipse under the action of central forces then the radial dependence of the force is inverse square with the distance from the centre. This discovery showed the physical significance of Kepler 's second law. In 1684 Halley , tired of Hooke 's boasting [M Nauenberg]:- ... asked Newton what orbit a body followed under an inverse square force, and Newton replied immediately that it would be an ellipse. However in 'De Motu..' he only gave a proof of the converse theorem that if the orbit is an ellipse the force is inverse square.

The proof that inverse square forces imply conic section orbits is sketched in Cor. 1 to Prop. 13 in Book 1 of the second and third editions of the 'Principia', but not in the first edition. Halley persuaded Newton to write a full treatment of his new physics and its application to astronomy. Over a year later (1687) Newton published the Philosophiae naturalis principia mathematica Ⓣ or Principia as it is always known. The Principia is recognised as the greatest scientific book ever written. Newton analysed the motion of bodies in resisting and non-resisting media under the action of centripetal forces. The results were applied to orbiting bodies, projectiles, pendulums, and free-fall near the Earth. He further demonstrated that the planets were attracted toward the Sun by a force varying as the inverse square of the distance and generalised that all heavenly bodies mutually attract one another. Further generalisation led Newton to the law of universal gravitation:- ... all matter attracts all other matter with a force proportional to the product of their masses and inversely proportional to the square of the distance between them.

Newton explained a wide range of previously unrelated phenomena: the eccentric orbits of comets, the tides and their variations, the precession of the Earth's axis, and motion of the Moon as perturbed by the gravity of the Sun. This work made Newton an international leader in scientific research. The Continental scientists certainly did not accept the idea of action at a distance and continued to believe in Descartes ' vortex theory where forces work through contact. However this did not stop the universal admiration for Newton's technical expertise. James II became king of Great Britain on 6 February 1685. He had become a convert to the Roman Catholic church in 1669 but when he came to the throne he had strong support from Anglicans as well as Catholics. However rebellions arose, which James put down but he began to distrust Protestants and began to appoint Roman Catholic officers to the army. He then went further, appointing only Catholics as judges and officers of state. Whenever a position at Oxford or Cambridge became vacant, the king appointed a Roman Catholic to fill it. Newton was a staunch Protestant and strongly opposed to what he saw as an attack on the University of Cambridge.

When the King tried to insist that a Benedictine monk be given a degree without taking any examinations or swearing the required oaths, Newton wrote to the Vice-Chancellor:- Be courageous and steady to the Laws and you cannot fail. The Vice-Chancellor took Newton's advice and was dismissed from his post. However Newton continued to argue the case strongly preparing documents to be used by the University in its defence. However William of Orange had been invited by many leaders to bring an army to England to defeat James. William landed in November 1688 and James, finding that Protestants had left his army, fled to France. The University of Cambridge elected Newton, now famous for his strong defence of the university, as one of their two members to the Convention Parliament on 15 January 1689. This Parliament declared that James had abdicated and in February 1689 offered the crown to William and Mary. Newton was at the height of his standing - seen as a leader of the university and one of the most eminent mathematicians in the world. However, his election to Parliament may have been the event which let him see that there was a life in London which might appeal to him more than the academic world in Cambridge.

After suffering a second nervous breakdown in 1693, Newton retired from research. The reasons for this breakdown have been discussed by his biographers and many theories have been proposed: chemical poisoning as a result of his alchemy experiments; frustration with his researches; the ending of a personal friendship with Fatio de Duillier, a Swiss-born mathematician resident in London; and problems resulting from his religious beliefs. Newton himself blamed lack of sleep but this was almost certainly a symptom of the illness rather than the cause of it. There seems little reason to suppose that the illness was anything other than depression, a mental illness he must have suffered from throughout most of his life, perhaps made worse by some of the events we have just listed. Newton decided to leave Cambridge to take up a government position in London becoming Warden of the Royal Mint in 1696 and Master in 1699. However, he did not resign his positions at Cambridge until 1701. As Master of the Mint, adding the income from his estates, we see that Newton became a very rich man. For many people a position such as Master of the Mint would have been treated as simply a reward for their scientific achievements.

Newton did not treat it as such and he made a strong contribution to the work of the Mint. He led it through the difficult period of recoinage and he was particularly active in measures to prevent counterfeiting of the coinage. In 1703 he was elected president of the Royal Society and was re-elected each year until his death. He was knighted in 1705 by Queen Anne, the first scientist to be so honoured for his work. However the last portion of his life was not an easy one, dominated in many ways with the controversy with Leibniz over which of them had invented the calculus. Given the rage that Newton had shown throughout his life when criticised, it is not surprising that he flew into an irrational temper directed against Leibniz . We have given details of this controversy in Leibniz 's biography and refer the reader to that article for details. Perhaps all that is worth relating here is how Newton used his position as President of the Royal Society . In this capacity he appointed an "impartial" committee to decide whether he or Leibniz was the inventor of the calculus.

He wrote the official report of the committee (although of course it did not appear under his name) which was published by the Royal Society , and he then wrote a review (again anonymously) which appeared in the Philosophical Transactions of the Royal Society. Newton's assistant Whiston had seen his rage at first hand. He wrote:- Newton was of the most fearful, cautious and suspicious temper that I ever knew. Article by: J J O'Connor and E F Robertson Click on this link to see a list of the Glossary entries for this page Biography: Sir Isaac Newton Biography: Sir Isaac Newton By Mary Bellis Updated August 14, 2016. Isaac Newton was born in 1642 in a manor house in Lincolnshire, England. His father had died two months before his birth. When Newton was three his mother remarried and he remained with his grandmother. He was not interested in the family farm so he was sent to Cambridge University to study. Isaac was born just a short time after the death of Galileo , one of the greatest scientists of all time. Galileo had proved that the planets revolve around the sun, not the earth as people thought at the time.

Isaac Newton was very interested in the discoveries of Galileo and others. Isaac thought the universe worked like a machine and that a few simple laws governed it. Like Galileo, he realized that mathematics was the way to explain and prove those laws. He formulated laws of motion and gravitation. These laws are math formulas that explain how objects move when a force acts on them. Isaac published his most famous book, Principia in 1687 while he was a mathematics professor at Trinity College in Cambridge. continue reading below our video Profile of Isaac Newton In the Principia, Isaac explained three basic laws that govern the way objects move. He also described his theory of gravity, the force that causes things to fall down. Newton then used his laws to show that the planets revolve around the suns in orbits that are oval, not round. The three laws are often called Newton’s Laws. The first law states that an object that is not being pushed or pulled by some force will stay still or will keep moving in a straight line at a steady speed. For example, if someone is riding a bike and jumps off before the bike is stopped what happens? The bike continues on until it falls over.

The tendency of an object to remain still or keep moving in a straight line at a steady speed is called inertia. The Second Law explains how a force acts on an object. An object accelerates in the direction the force is moving it. If someone gets on a bike and pushes the pedals forward the bike will begin to move. If someone gives the bike a push from behind, the bike will speed up. If the rider pushes back on the pedals the bike will slow down. If the rider turns the handlebars, the bike will change direction. The Third Law states that if an object is pushed or pulled, it will push or pull equally in the opposite direction. If someone lifts a heavy box, they use force to push it up. The box is heavy because it is producing an equal force downward on the lifter’s arms. The weight is transferred through the lifter’s legs to the floor. The floor also presses upward with an equal force. If the floor pushed back with less force, the person lifting the box would fall through the floor. If it pushed back with more force the lifter would fly up toward the air. When most people think of Isaac Newton, they think of him sitting under an apple tree observing an apple fall to the ground.

When he saw the apple fall, Newton began to think about a specific kind of motion called gravity. Newton understood that gravity was a force of attraction between two objects. He also understood that an object with more matter or mass exerted the greater force, or pulled smaller objects toward it. That meant that the large mass of the earth pulled objects toward it. That is why the apple fell down instead of up and why people don’t float in the air. He also thought that maybe gravity was not just limited to the earth and the objects on the earth. What if gravity extended to the moon and beyond? Newton calculated the force needed to keep the moon moving around the earth. Then he compared it with the force that made the apple fall downward. After allowing for the fact that the moon is much farther from the earth, and has a much greater mass, he discovered that the forces were the same and that the moon is also held in orbit around earth by the pull of earth’s gravity. Newton’s calculations changed the way people understood the universe. Prior to Newton, no one had been able to explain why the planets stayed in their orbits. What held them in place? People had thought that the planets were held in place by an invisible shield.

Isaac proved that they were held in place by the sun’s gravity and that the force of gravity was affected by distance and by mass. While he was not the first to understand that the orbit of a planet was elongated like an oval, he was the first to explain how it worked. Isaac Newton Biography - Newton's Life, Career, Work - Dr Robert A. Hatch Isaac Newton, Biography, Information, Sources -Dr Robert A. Hatch S I R I S A A C N E W T O N Dr Robert A. Hatch - University of Florida Newton, Sir Isaac (1642-1727), English natural philosopher, generally regarded as the most original and influential theorist in the history of science. In addition to his invention of the infinitesimal calculus and a new theory of light and color, Newton transformed the structure of physical science with his three laws of motion and the law of universal gravitation. As the keystone of the scientific revolution of the 17th century, Newton's work combined the contributions of Copernicus, Kepler, Galileo, Descartes, and others into a new and powerful synthesis.

Three centuries later the resulting structure - classical mechanics - continues to be a useful but no less elegant monument to his genius. Life & Character - Isaac Newton was born prematurely on Christmas day 1642 (4 January 1643, New Style) in Woolsthorpe, a hamlet near Grantham in Lincolnshire. The posthumous son of an illiterate yeoman (also named Isaac), the fatherless infant was small enough at birth to fit 'into a quartpot.' When he was barely three years old Newton's mother, Hanna (Ayscough), placed her first born with his grandmother in order to remarry and raise a second family with Barnabas Smith, a wealthy rector from nearby North Witham. Much has been made of Newton's posthumous birth, his prolonged separation from his mother, and his unrivaled hatred of his stepfather. Until Hanna returned to Woolsthorpe in 1653 after the death of her second husband, Newton was denied his mother's attention, a possible clue to his complex character. Newton's childhood was anything but happy, and throughout his life he verged on emotional collapse, occasionally falling into violent and vindictive attacks against friend and foe alike.

With his mother's return to Woolsthorpe in 1653, Newton was taken from school to fulfill his birthright as a farmer. Happily, he failed in this calling, and returned to King's School at Grantham to prepare for entrance to Trinity College, Cambridge. Numerous anecdotes survive from this period about Newton's absent-mindedness as a fledging farmer and his lackluster performance as a student. But the turning point in Newton's life came in June 1661 when he left Woolsthorpe for Cambridge University. Here Newton entered a new world, one he could eventually call his own. Although Cambridge was an outstanding center of learning, the spirit of the scientific revolution had yet to penetrate its ancient and somewhat ossified curriculum. Little is known of Newton's formal studies as an undergraduate, but he likely received large doses of Aristotle as well as other classical authors. And by all appearances his academic performance was undistinguished. In 1664 Isaac Barrow, Lucasian Professor of Mathematics at Cambridge, examined Newton's understanding of Euclid and found it sorely lacking.

We now know that during his undergraduate years Newton was deeply engrossed in private study, that he privately mastered the works of René Descartes, Pierre Gassendi, Thomas Hobbes, and other major figures of the scientific revolution. A series of extant notebooks shows that by 1664 Newton had begun to master Descartes' Géométrie and other forms of mathematics far in advance of Euclid's Elements. Barrow, himself a gifted mathematician, had yet to appreciate Newton's genius. In 1665 Newton took his bachelor's degree at Cambridge without honors or distinction. Since the university was closed for the next two years because of plague, Newton returned to Woolsthorpe in midyear. There, in the following 18 months, he made a series of original contributions to science.

As he later recalled, 'All this was in the two plague years of 1665 and 1666, for in those days I was in my prime of age for invention, and minded mathematics and philosophy more than at any time since.' In mathematics Newton conceived his 'method of fluxions' (infinitesimal calculus), laid the foundations for his theory of light and color, and achieved significant insight into the problem of planetary motion, insights that eventually led to the publication of his Principia (1687). In April 1667, Newton returned to Cambridge and, against stiff odds, was elected a minor fellow at Trinity. Success followed good fortune. In the next year he became a senior fellow upon taking his master of arts degree, and in 1669, before he had reached his 27th birthday, he succeeded Isaac Barrow as Lucasian Professor of Mathematics. The duties of this appointment offered Newton the opportunity to organize the results of his earlier optical researches, and in 1672, shortly after his election to the Royal Society, he communicated his first public paper, a brilliant but no less controversial study on the nature of color.

In the first of a series of bitter disputes, Newton locked horns with the society's celebrated curator of experiments, the bright but brittle Robert Hooke. The ensuing controversy, which continued until 1678, established a pattern in Newton's behavior. After an initial skirmish, he quietly retreated. Nonetheless, in 1675 Newton ventured another yet another paper, which again drew lightning, this time charged with claims that he had plagiarized from Hooke. The charges were entirely ungrounded. Twice burned, Newton withdrew. In 1678, Newton suffered a serious emotional breakdown, and in the following year his mother died. Newton's response was to cut off contact with others and engross himself in alchemical research. These studies, once an embarrassment to Newton scholars, were not misguided musings but rigorous investigations into the hidden forces of nature. Newton's alchemical studies opened theoretical avenues not found in the mechanical philosophy, the world view that sustained his early work. While the mechanical philosophy reduced all phenomena to the impact of matter in motion, the alchemical tradition upheld the possibility of attraction and repulsion at the particulate level. Newton's later insights in celestial mechanics can be traced in part to his alchemical interests.

By combining action-at-a-distance and mathematics, Newton transformed the mechanical philosophy by adding a mysterious but no less measurable quantity, gravitational force. In 1666, as tradition has it, Newton observed the fall of an apple in his garden at Woolsthorpe, later recalling, 'In the same year I began to think of gravity extending to the orb of the Moon.' Newton's memory was not accurate. In fact, all evidence suggests that the concept of universal gravitation did not spring full-blown from Newton's head in 1666 but was nearly 20 years in gestation. Ironically, Robert Hooke helped give it life. In November 1679, Hooke initiated an exchange of letters that bore on the question of planetary motion. Although Newton hastily broke off the correspondence, Hooke's letters provided a conceptual link between central attraction and a force falling off with the square of distance. Sometime in early 1680, Newton appears to have quietly drawn his own conclusions. Meanwhile, in the coffeehouses of London, Hooke, Edmund Halley, and Christopher Wren struggled unsuccessfully with the problem of planetary motion.

Finally, in August 1684, Halley paid a legendary visit to Newton in Cambridge, hoping for an answer to his riddle: What type of curve does a planet describe in its orbit around the sun, assuming an inverse square law of attraction? When Halley posed the question, Newton's ready response was 'an ellipse.' When asked how he knew it was an ellipse Newton replied that he had already calculated it. Although Newton had privately answered one of the riddles of the universe--and he alone possessed the mathematical ability to do so--he had characteristically misplaced the calculation. After further discussion he promised to send Halley a fresh calculation forthwith. In partial fulfillment of his promise Newton produced his De Motu of 1684. From that seed, after nearly two years of intense labor, the Philosophiae Naturalis Principia Mathematica appeared. Arguably, it is the most important book published in the history of science. But if the Principia was Newton's brainchild, Hooke and Halley were nothing less than midwives. Although the Principia was well received, its future was cast in doubt before it appeared.

Here again Hooke was center stage, this time claiming (not without justification) that his letters of 1679-1680 earned him a role in Newton's discovery. But to no effect. Newton was so furious with Hooke that he threatened to suppress Book III of the Principia altogether, finally denouncing science as 'an impertinently litigious lady.' Newton calmed down and finally consented to publication. But instead of acknowledging Hooke's contribution Newton systematically deleted every possible mention of Hooke's name. Newton's hatred for Hooke was consumptive. Indeed, Newton later withheld publication of his Opticks (1704) and virtually withdrew from the Royal Society until Hooke's death in 1703. After publishing the Principia, Newton became more involved in public affairs. In 1689 he was elected to represent Cambridge in Parliament, and during his stay in London he became acquainted with John Locke, the famous philosopher, and Nicolas Fatio de Duillier, a brilliant young mathematician who became an intimate friend. In 1693, however, Newton suffered a severe nervous disorder, not unlike his breakdown of 1677-1678.

The cause is open to interpretation: overwork; the stress of controversy; the unexplained loss of friendship with Fatio; or perhaps chronic mercury poisoning, the result of nearly three decades of alchemical research. Each factor may have played a role. We only know Locke and Samuel Pepys received strange and seemingly deranged letters that prompted concern for Newton's 'discomposure in head, or mind, or both.' Whatever the cause, shortly after his recovery Newton sought a new position in London. In 1696, with the help of Charles Montague, a fellow of Trinity and later earl of Halifax, Newton was appointed Warden and then Master of the Mint. His new position proved 'most proper,' and he left Cambridge for London without regret. During his London years Newton enjoyed power and worldly success. His position at the Mint assured a comfortable social and economic status, and he was an active and able administrator. After the death of Hooke in 1703, Newton was elected president of the Royal Society and was annually reelected until his death. In 1704 he published his second major work, the Opticks, based largely on work completed decades before. He was knighted in 1705.

Although his creative years had passed, Newton continued to exercise a profound influence on the development of science. In effect, the Royal Society was Newton's instrument, and he played it to his personal advantage. His tenure as president has been described as tyrannical and autocratic, and his control over the lives and careers of younger disciples was all but absolute. Newton could not abide contradiction or controversy - his quarrels with Hooke provide singular examples. But in later disputes, as president of the Royal Society, Newton marshaled all the forces at his command. For example, he published Flamsteed's astronomical observations - the labor of a lifetime - without the author's permission; and in his priority dispute with Leibniz concerning the calculus, Newton enlisted younger men to fight his war of words, while behind the lines he secretly directed charge and countercharge. In the end, the actions of the Society were little more than extensions of Newton's will, and until his death he dominated the landscape of science without rival. He died in London on March 20, 1727 (March 31, New Style). Scientific Achievements Mathematics - The origin of Newton's interest in mathematics can be traced to his undergraduate days at Cambridge.

Here Newton became acquainted with a number of contemporary works, including an edition of Descartes Géométrie, John Wallis' Arithmetica infinitorum, and other works by prominent mathematicians. But between 1664 and his return to Cambridge after the plague, Newton made fundamental contributions to analytic geometry, algebra, and calculus. Specifically, he discovered the binomial theorem, new methods for expansion of infinite series, and his 'direct and inverse method of fluxions.' As the term implies, fluxional calculus is a method for treating changing or flowing quantities. Hence, a 'fluxion' represents the rate of change of a 'fluent'--a continuously changing or flowing quantity, such as distance, area, or length. In essence, fluxions were the first words in a new language of physics. Newton's creative years in mathematics extended from 1664 to roughly the spring of 1696. Although his predecessors had anticipated various elements of the calculus, Newton generalized and integrated these insights while developing new and more rigorous methods.

The essential elements of his thought were presented in three tracts, the first appearing in a privately circulated treatise, De analysi (On Analysis),which went unpublished until 1711. In 1671, Newton developed a more complete account of his method of infinitesimals, which appeared nine years after his death as Methodus fluxionum et serierum infinitarum (The Method of Fluxions and Infinite Series, 1736). In addition to these works, Newton wrote four smaller tracts, two of which were appended to his Opticks of 1704. Newton and Leibniz. Next to its brilliance, the most characteristic feature of Newton's mathematical career was delayed publication. Newton's priority dispute with Leibniz is a celebrated but unhappy example. Gottfried Wilhelm Leibniz, Newton's most capable adversary, began publishing papers on calculus in 1684, almost 20 years after Newton's discoveries commenced. The result of this temporal discrepancy was a bitter dispute that raged for nearly two decades. The ordeal began with rumors that Leibniz had borrowed ideas from Newton and rushed them into print. It ended with charges of dishonesty and outright plagiarism.

The Newton-Leibniz priority dispute--which eventually extended into philosophical areas concerning the nature of God and the universe--ultimately turned on the ambiguity of priority. It is now generally agreed that Newton and Leibniz each developed the calculus independently, and hence they are considered co-discoverers. But while Newton was the first to conceive and develop his method of fluxions, Leibniz was the first to publish his independent results. Optics. Newton's optical research, like his mathematical investigations, began during his undergraduate years at Cambridge. But unlike his mathematical work, Newton's studies in optics quickly became public. Shortly after his election to the Royal Society in 1671, 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. In 1665-1666, 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.' The Crucial Experiment. Newton'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. Newton'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.' Newton probably conducted a number of his prism experiments at Cambridge before the plague forced him to return to Woolsthorpe. His Lucasian lectures, later published in part as Optical Lectures (1728), supplement other researches published in the Society's Transactions dating from February 1672. The Opticks. The Opticks of 1704, 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.' Divided into three books, the Opticks moves from definitions, axioms, propositions, and theorems to proof by experiment. A subtle blend of mathematical reasoning and careful observation, the Opticks became the model for experimental physics in the 18th century. The Corpuscular Theory. But 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. At 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 1717, 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. The question of periodicity arose with the phenomenon known as 'Newton's rings.' In book II of the Opticks, Newton describes a series of experiments concerning the colors of thin films. 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.' After making careful measurements, Newton found that the thickness of the film of air between the lens (of a given curvature) and the glass corresponded to the spacing of the rings. If dark rings occurred at thicknesses of 0, 2, 4, 6... , then the colored rings corresponded to an odd number progression, 1, 3, 5, 7, .... 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.

The Opticks was Newton's most widely read work. Following the first edition, Latin versions appeared in 1706 and 1719, and second and third English editions in 1717 and 1721. 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. Mechanics. Newton's research in dynamics falls into three major periods: the plague years 1664-1666, the investigations of 1679-1680, following Hooke's correspondence, and the period 1684-1687, 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.' While the myth of Newton and the apple maybe true, the traditional account of Newton and gravity is not.

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-1660'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. The 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. Assuming Galileo's estimate that the moon is 60 earth radii from the earth, the restraint on the moon should have been 1/3600 (1/602) of the gravitational acceleration on earth. But Newton's estimate of the size of the earth was too low, and his calculation showed the effect on the moon to be about 1/4000 of that on earth. As Newton later described it, the moon test answered 'pretty nearly.' But the figures for the moon were not exact, and Newton abandoned the problem. In late 1679 and early 1680 an exchange of letters with Hooke renewed Newton's interest. In November 1679, nearly 15 years after the moon test, Hooke wrote Newton concerning a hypothesis presented in his Attempt to Prove the Motion of the Earth (1674).

Here Hooke proposed that planetary orbits result from a tangential motion and 'an attractive motion towards the centrall body.' In later letters Hooke further specified a central attracting force that fell off with the square of distance. As a result of this exchange Newton rejected his earlier notion of centrifugal tendencies in favor of central attraction. Hooke's letters provided crucial insight. But in retrospect, if Hooke's intuitive power seems unparalleled, it never approached Newton's mathematical power in principle or in practice. When Halley visited Cambridge in 1684, Newton had already demonstrated the relation between an inverse square attraction and elliptical orbits. To Halley's 'joy and amazement,' Newton apparently succeeded where he and others failed. With this, Halley's role shifted, and he proceeded to guide Newton toward publication. Halley personally financed the Principia and saw it through the press to publication in July 1687. The Principia. Newton's masterpiece is divided into three books. Book I of the Principia begins with eight definitions and three axioms, the latter now known as Newton's laws of motion.

No discussion of Newton would be complete without them: (1) Every body continues in its state of rest, or uniform motion in a straight line, unless it is compelled to change that state by forces impressed on it (inertia). (2) The change in motion is proportional to the motive force impressed and is made in the direction of the straight line in which that force is impressed (F = ma). (3) To every action there is always an opposed and equal reaction. Following these axioms, Newton proceeds step by step with propositions, theorems, and problems. In Book II of the Principia, Newton treats the Motion of bodies through resisting mediums as well as the motion of fluids themselves. Since Book II was not part of Newton's initial outline, it has traditionally seemed somewhat out of place. Nonetheless, it is noteworthy that near the end of Book II (Section IX) Newton demonstrates that the vortices invoked by Descartes to explain planetary motion could not be self-sustaining; nor was the vortex theory consistent with Kepler's three planetary rules. The purpose of Book II then becomes clear.

After discrediting Descartes' system, Newton concludes: 'How these motions are performed in free space without vortices, may be understood by the first book; and I shall now more fully treat of it in the following book.' In Book III, subtitled the System of the World, Newton extended his three laws of motion to the frame of the world, finally demonstrating 'that there is a power of gravity tending to all bodies, proportional to the several quantities of matter which they contain.' Newton's law of universal gravitation states that F = G Mm/R2; that is, that all matter is mutually attracted with a force (F) proportional to the product of their masses (Mm) and inversely proportional to the square of distance (R2) between them. G is a constant whose value depends on the units used for mass and distance. To demonstrate the power of his theory, Newton used gravitational attraction to explain the motion of the planets and their moons, the precession of equinoxes, the action of the tides, and the motion of comets. In sum, Newton's universe united heaven and earth with a single set of laws. It became the physical and intellectual foundation of the modern world view.

Perhaps the most powerful and influential scientific treatise ever published, the Principia appeared in two further editions during Newton's lifetime, in 1713 and 1726. Other Researches. Throughout his career Newton conducted research in theology and history with the same passion that he pursued alchemy and science. Although some historians have neglected Newton's nonscientific writings, there is little doubt of his devotion to these subjects, as his manuscripts amply attest. Newton's writings on theological and biblical subjects alone amount to about 1.3 million words, the equivalent of 20 of today's standard length books. Although these writings say little about Newtonian science, they tell us a good deal about Isaac Newton. Newton's final gesture before death was to refuse the sacrament, a decision of some consequence in the 18th century. Although Newton was dutifully raised in the Protestant tradition his mature views on theology were neither Protestant, traditional, nor orthodox. In the privacy of his thoughts and writings, Newton rejected a host of doctrines he considered mystical, irrational, or superstitious. In a word, he was a Unitarian. Newton's research outside of science--in theology, prophecy, and history--was a quest for coherence and unity.

His passion was to unite knowledge and belief, to reconcile the Book of Nature with the Book of Scripture. But for all the elegance of his thought and the boldness of his quest, the riddle of Isaac Newton remained. In the end, Newton is as much an enigma to us as he was, no doubt, to himself. Robert A. Hatch

Question: In which county was Isaac Newton born?
Answer: Lincolnshire