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Sir Isaac Newton (1642 - 1727)

Isaac Newton was born in Woolsthorpe, near Grantham in Lincolnshire, which is in the north of England. His father had died a few months before he was born and his mother was left without very much money. When Newton was three years old his mother, Hannah Ayscough, married a churchman, a certain Reverend Barnabus Smith, and the couple moved away from Grantham. They left Newton with his grandparents in Woolsthorpe. Newton attended local village schools until he was twelve years old, at which point he was sent to Grantham to attend the free grammar school.

His mother had returned to Woolsthorpe after his step-father died a couple of years before Newton was sent to Grantham. She seems to have wanted Newton to work on the family farm and was never keen on sending him to university. It was only because his uncle, William Ayscough, spoke up for him that she was eventually persuaded to let him go. Newton's mother, who by this time was quite wealthy, may have given her permission but she did not want to pay for his education. When Newton entered Trinity College, Cambridge in 1661, to study mathematics, he was a "sizar", which means that he had to earn money by doing chores for other, better-off, students.

In 1665 there was an epidemic of the plague, also known as the Black Death, in the south of England and Cambridge University closed, sending its students home. Newton returned to Woolsthorpe where, for two years, he was able to concentrate fully on his research. His investigations covered many areas that included calculus, geometry, optics and light, and gravitation. It was during these years in Woolsthorpe that he started his famous book, Philosophiae Naturalis Principia Mathematica, which translated from the Latin means "Mathematical Principles of Natural Philosophy". This book, often referred to as the Principia, would not be published for another twenty years.

It was the publication of three papers on calculus in 1666 that made Newton a name for himself with the academic community. In 1667 he was made a Fellow of Trinity College and he became the second Lucasian Professor of Mathematics in 1669. This position had been founded in 1663 when Henry Lucas, a Member of Parliament, had donated money to the university. (It is interesting to note that the present Lucasian Professor of Mathematics is Stephen Hawking.) Newton stayed at Trinity College as professor and lecturer until 1696.


Isaac Newton

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In 1668 Newton made the first reflecting telescope. This type of telescope was much smaller than the refracting telescopes that were in use at the time; a mere 10cm long, and yet it allowed more than x30 magnification. Newton's invention was brought to the attention of the Fellows of the Royal Society who were really impressed by it. The telescope was excellent for looking at planets that did not reflect very much light, such as Jupiter. One person who did not appreciate Newton's work on optics and light was Robert Hooke. Hooke considered himself to be the expert in these fields and was quick to try to pull Newton's work apart.

Newton joined the Royal Society in 1671 and become President in 1703. He was known as an arrogant man who could not stand to be criticized. On the continent he had other adversaries. Christiaan Huygens questioned his work and the French physicist, Edmé Mariotte, made matters worse when he declared that he had tried to reproduce some of Newton's experiments on optics and that he could not get them to work. The opposition from the continent, as well as at home, may well have contributed towards the mental breakdown that Newton suffered in 1675 and that took four years for him to fully recover from.

Halley paid Newton a visit in 1684 with questions about a comet's path as it orbited the Sun. Halley had been amazed that Newton could immediately reply that it was elliptical. When Newton showed Halley all of his work, Halley was quick to realise how important the information was to the scientific world and urged Newton to publish his findings. In fact, when the Royal Society could not afford to publish Philosophiæ Naturalis Principia Mathematica, it was Halley who paid the bill.

The Principia, published on 5th July 1687 describes Newton's laws of motion. The first law of motion states that an object that is not moving will remain still and that a moving object will continue to move at the same speed, so long as there are no other factors, such as friction, affecting it. In space an object will continue to move at the same speed because there is no friction. In his second law, Newton states that the force used on an object is equal to the mass of the object multiplied by the change in speed of the object (force = mass x change of speed). The third law of motion simply states that every action has an equal and opposite reaction.

These three universal laws allowed Newton to formulate the laws of gravitation. There is a story that Newton started to understand gravitation when an apple dropped from the apple tree he was sitting against at the time. It is unknown if the story about an apple falling on Newton's head, is true! What is true is that Newton realised that gravity extended beyond the apple tree and out into space. He realised that the Moon's orbit around the Earth was a consequence of the Earth's pull on the Moon (gravity) and the speed at which the Moon was moving. Newton came to the conclusion that any two objects in space will affect each other with their gravitational forces. The Earth's gravitational pull keeps the Moon in orbit and the Moon's gravitational pull on the Earth produces tides.

The publishing of Principia sparked another row between Newton and Robert Hooke. In 1679 Hooke, then secretary of the Royal Society, had written to Newton to ask him about his thoughts on gravity. During an exchange of letters, Hooke probably (and inadvertently) provided the link that allowed Newton to work out the inverse square law of gravity. Hooke was furious when Newton did not acknowledge his contribution and he was convinced that the inverse square law of gravity had been his brain child. Hooke was probably in the right and Newton acted in bad faith by not giving him the credit he was due. It is interesting that Newton did not publish Opticks: Or, a Treatise of the Reflexions, Refractions, Inflexions and Colours of Light until one year after Hooke's death. Some researchers think that, when Newton became President of the Royal Society in 1703 he deliberately suppressed Hooke's work and may have disposed of the only portrait of Hooke, if it ever existed.

Newton was a Member of Parliament (MP) for Cambridge University in 1689. He stood for office to fight King James's attempts to make Cambridge University a Catholic establishment. He was made Warden of the Royal Mint (the place where the money is made) in 1996 and Master of the Royal Mint in 1699. In 1705 he was knighted at Cambridge by the new monarch, Queen Anne. Newton never married; his niece took care of him in later life as he became more and more eccentric. Newton had worked in the field of alchemy (chemistry), as well as mathematics and physics, during his life and his eccentricity was probably the effect of the element mercury that had accumulated in his body. He died in 1727 and was buried with full honours in Westminster Abbey.


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