Sir Isaac Newton

4 Jan 1643 in Woolsthorpe, Lincolnshire, England

31 March 1727 in London, England

Isaac Newton was born on 4th January, 1643  in the manor house of Woolsthorpe, near Grantham in Lincolnshire. He 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.

Little is known about what Isaac learnt in preparation for university. But 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.

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 particularly of  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.

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.

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.

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.

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. 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.

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.

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.
Newton wrote  a full treatment of his new physics and its application to astronomy. Over a year later (1687) Newton published the  Principia    .
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.

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 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 had invented the calculus.
Newton, the great man did possess certain human weakness of a common man, he suffered a rage against Leibniz life long.
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.
– Courtesy Web World

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