Sir Isaac Newton

Sir Isaac Newton

Isaac Newton is popularly remembered as the man who saw an apple fall from a tree, and was inspired to invent the theory of gravity. If you have know about elementary physics then you know that he invented calculus and the three laws of motion upon which all of mechanics is based. Most of all, Newton's mathematical approach has become so basic to all of physics that he is generally regarded as the father of the clockwork universe: the first, and perhaps the greatest, physicist.

Isaac Newton was born in the manor house of Woolsthorpe, near Grantham in Lincolnshire. Although he was born on Christmas Day 1642, the date given on this card is the Gregorian calendar date. (The Gregorian calendar was not adopted in England until 1752.) Newton came from a family of farmers but never knew his father who died before he was born. His mother remarried, moved to a nearby village, and left him with his grandmother.

When his stepfather died in 1656, Newton's mother removed him from grammar school in Grantham where he had shown little promise in academic work. His school reports said that he was 'idle' and 'inattentive'. An uncle decided that he should be prepared for the university, and he entered his uncle's old College, Trinity College, Cambridge, in June 1661. Newton's goal 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, and Boyle. The new algebra and analytical geometry of Vieoe, Descartes, and Wallis, and the mechanics of the Copernican astronomy of Galileo attracted him.

Newton's talent began to show on the arrival of Barrow to the Lucasian chair at Cambridge. His scientific genius suddenly was noticed 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 to make advances in mathematics, optics, physics, chemistry, and astronomy. While Newton stayed at home he laid the foundation for differential and integral calculus, several years before its independent discovery by Leibniz.

The 'method of fluxions', as he called it, was based on his ideas that the integration of a function is the inverse procedure to differentiating it. Taking differentiation as the basic operation, Newton came up with simple methods that showed many separate techniques previously developed to solve 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. Barrow resigned the Lucasian chair in 1669 recommending that Newton be appointed in his place.

Newton's first work as Lucasian Professor was on optics. 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 that it was differnet .

When he passed a thin beam of sunlight through a glass prism Newton noticed the spectrum of colours that was formed. Newton didn't think that white light is really a mixture of many different types of rays which at slightly different angles, and that each different type of ray produces a different spectral colour.

Newton concluded that telescopes using refracting lenses would always suffer « chromatic aberration ». He then constructed a reflecting telescope.

Newton was elected a fellow of the Royal Society in 1672 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 . His paper was read by Hooke and Huygens. They did not like it. Newton's attempt to prove, by experiment alone, that light consists of the motion of small particles rather than waves.

He waited for the publication of his optical researches until after the death of Hooke in 1703. Newton's Opticks appeared in 1704. It talked about the theory of light and colour and with (i) « investigations of the colours of thin sheets » (ii) « 'Newton's rings' » and (iii) » « diffraction of light ». To explain some of his observations he had to use a wave theory of light with his « corpuscular theory ».

Newton's greatest achievement was his work in physics and celestial mechanics, which led to the theory of universal gravitation. By the time it was 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. 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 came up with a law called the « inverse- square law ».

After suffering a nervous breakdown in 1693, Newton retired from research to take up a government position in London becoming Warden of the Royal Mint (1696) and Master(1699). In 1703 he was elected president of the Royal Society and was re-elected each year until his death.

He was knighted in 1708 by Queen Anne, the first scientist to be so honoured for his work.

It is truely no exaggeration to identify Newton as one of the histories single most important contributor to the development of modern science.

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