Sir Isaac Newton
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.|
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 tend to commonly say, as the corrected Gregorian calendar date, that he was born on the 4th of January 1643. His father, also named Isaac, died three months before his son was born. Isaac was the son of a farmer and although his father owned property and animals which made him quite a wealthy man, he was completely uneducated and could not sign his own name.
When he was barely three years old, Newton's mother, Hanna Ayscough, placed her first born with his grandmother Margery Ayscough, in Woolsthorpe, in order to remarry and raise a second family with Barnabas Smith, the wealthy Minister of the Church of North Witham. Basically treated as an orphan, Isaac did not have a happy childhood. He never mentioned in his life his grandfather, James Ayscough, who didn’t even mention Isaac in his will and left him nothing. Isaac probably had a hard childhood which can be a possible clue to his complex character. He felt bitter towards his mother and her husband, whom he hated, and once confessed “threatening my father and mother Smith to burn then and the house over them”.
After the death of her second husband, in 1653, Hannah and her family (one son and two daughters), came back to Woolsthorpe.
Shortly after her return, Isaac began attending the Free Grammar school on Grantham, where he lived with the Headmaster of the School, Stokes. Although Isaac didn’t appear to be a serious and wise student, Stokes persuaded his mother to let him go to university.
Numerous anecdotes survive from this period about Newton's period at the school and his absent-mindedness as a fledging farmer and his lackluster performance as a student.
In June 1661, Isaac enters Trinity College Cambridge, the University of his Uncle. Despite the fact that his mother was financially well off, he entered as a sizar, which means he was a student who received an allowance toward college expenses in exchange for acting as a servant for other students.
Newton’s aim was a Law degree. At Cambridge, Newton studied the philosophy of Aristotle, Descartes, Gassendi, Hobbes and 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 (Certain Philosophical Questions). 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.
It is common 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. He tested Newton’s knowledge of Euclide and found it too poor. 1663 matches the beginnings of Newton’s deep mathematical studies. However, Barrow recognized Isaac’s genius only a few years later.
On April 1664, Newton was elected a scholar and received his bachelor’s degree in 1665.
After the university had to close for plague reasons in 1665, he had to return to Lincolnshire. That is when his genius started to emerge. In less than two years, he began revolutionary advances in mathematics, optics, physics and astronomy.
While at home, Newton 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 reopened in 1667, Newton put himself forward as a candidate for a fellowship. He then was successively elected to a minor fellowship before having his Master’s degree, then major fellowship in 1668.
In 1969, Barrow sent Newton’s work to Collins in London. Collins corresponded with all the leading mathematicians of the day so barrow’s action should have led quick recognition. After Barrow resigned the Lucasian chair in 1969, he recommended Newton to be appointed at his place.
Newton’s first work as Lucasian Professor was on optics which was the topic of his first lecture as well.
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 published his first scientific paper on light and color in the Philosophical Transactions of the Royal Society, and was elected a fellow at 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.
But Newton’s character didn’t help him to making his results known to the world. On one hand, he wanted fame and recognition, on the other hand he hated criticism and so the easiest way not to be criticized was not to publish. However, his corpuscular theory reigned until the wave theory was revived in the 19th century.
After a hard fight with Hooke, who pretended Newton had stolen some of his optical results, and formal letters to make peace, Newton left the Royal Society to which he associated Hooke as one of its leaders. He waited until after the death of Hooke in 1703, to publish his optical researches. In 1704, Newton’s Optiks appeared. The main subject was the theory of light and color.
In 1678, after a hard argument with the English Jesuits in Liège over his theory of colour, he had a nervous breakdown. His mother died the following year and Newton withdrew even more from people and crowd for many 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 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. 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.
When James II became king of Great Britain in 1685, and after some protestant rebellion, James decided to appoint at important posts only Roman Catholics, as he was. Whenever a place at Oxford or Cambridge was vacant he would appoint a roman catholic to fill it. That led to the firm opposition of Newton, who was a protestant. He fought a lot against this kind a dictatorship until William of Orange took over Great Britain. Newton was then elected as a member of their Convention Parliament of Cambridge University. 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.
In 1693, Newton suffered another nervous breakdown and then retired from research. In 1696, he left Cambridge and became Warden of the Royal Mint, then Master in 1699.
In 1703, he was elected president of the Royal Society and was re-elected each year until his death. In 1705, he was knighted by Queen Anne, being the first scientist to be so honored for his work.
The last years of his life were not easy. The important controversy with Leibniz, over which he had invented the calculus, almost destroyed him, knowing how irrational and violent he could be. As the president of the Royal Society, he appointed a “impartial committee” to decide whether he or Leibniz had invented the calculus. He then published anonymously the results of the committee in the Philosophical Transactions of the Royal Society.
Newton died in London on 31 March 1727 and was buried in Westminster Abbey.
The Apple story:
“When Newton saw an apple fall, he found
In that slight startle from his contemplation —
'Tis said (for I'll not answer above ground
For any sage's creed or calculation) —
A mode of proving that the earth turn'd round
In a most natural whirl, called "gravitation;"
And this is the sole mortal who could grapple,
Since Adam, with a fall or with an apple.”
A popular story claims that Newton was inspired to formulate his theory of universal gravitation by the fall of an apple from a tree. Cartoons have gone further to suggest the apple actually hit Newton's head, and that its impact somehow made him aware of the force of gravity. John Conduitt, Newton's assistant at the Royal Mint and husband of Newton's niece, described the event when he wrote about Newton's life:
“In the year 1666 he retired again from Cambridge to his mother in Lincolnshire. Whilst he was pensively meandering in a garden it came into his thought that the power of gravity (which brought an apple from a tree to the ground) was not limited to a certain distance from earth, but that this power must extend much further than was usually thought. Why not as high as the Moon said he to himself & if so, that must influence her motion & perhaps retain her in her orbit, whereupon he fell a calculating what would be the effect of that supposition.”
The question was not whether gravity existed, but whether it extended so far from Earth that it could also be the force holding the moon to its orbit. Newton showed that if the force decreased as the inverse square of the distance, one could indeed calculate the Moon's orbital period, and get good agreement. He guessed the same force was responsible for other orbital motions, and hence named it "universal gravitation".