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Isaac Newton

Sir Isaac Newton (25 December 1642 - 20 March 1726/27) was an English mathematician, physicist, astronomer, theologian, and author, widely recognized as one of the greatest and most influential mathematicians and scientists of all time, and as a key figure in the scientific revolution.

**Biography**

Isaac Newton was born on January 4, 1643, although at that time the calendar used was the Julian one, corresponding to December 25, 1642, Christmas Day.

The birth was premature and no one thought he could live long.

His parents were Isaac Newton and Hannah Ayscough, two Puritan peasants, and he did not get to know his father, as he died in October 1642.

When his mother remarried Barnabas Smith, he had no intention of caring for the child and left him in the care of his grandmother, with whom he lived until his stepfather's death in 1653.

This was possibly a traumatic event for Isaac, it constituted the loss of the mother without having met the father.

He never gave a good memory to his grandmother and went unnoticed until his death. The same happened with the grandfather, who seemed not to exist until it was discovered that he was also present in the house.

When Barnabás Smith died, his mother returned to the family home accompanied by two children from this marriage, her stepbrothers, but the family union lasted less than two years.

Isaac was sent to study at The King's School in Grantham at the age of twelve. What is known from this stage is that he studied Latin, some Greek, and the basics of geometry and arithmetic.

In 1659 he bought a pocket book, and on the first page of which he wrote in Latin "Martij 19, 1659".

It represented the period between 1659 and 1660, which coincided with the period of his return to his hometown, and most of his writings are dedicated to the "Utilissimum prosodiae Suppleum". Years later, an edition of Pindar signed by Newton and dated 1659 is in the Keynes collection at King's College.

The primary studies were of great use to Newton; the works on mathematics were written in Latin, like the writings on natural philosophy, and later they allowed him to come into contact with European scientists.

At that time another important topic was the study of the Bible and it was read in classical languages supporting the classical program and expanding the Protestant faith of England.

In Isaac's case, studying this subject, along with the library he inherited from his stepfather, could have started him on a journey into theology.

In the anecdotes of his friend William Stukeley Newton's genius was already recognized and people remembered his rare inventions and his great capacity for mechanical work. He filled his room with tools that he acquired with the money his mother gave him. He made wooden objects, doll furniture and especially models. He also managed to reproduce a windmill built at the time north of Grantham.

The model replicated by Newton improved on the original, and it worked when he placed it on the ceiling. Other Newton constructions were a four-wheeled cart powered by a crank that operated from within.

Another was a folded paper lantern to get to school on dark winter days that was also used tied to the tail of a kite to scare neighbors at night.

He studied the properties of kites, calculated the ideal proportions and the most suitable points to adjust the strings. In addition, he gave flashlights to his classmates and commented on his studies with the apparent purpose of winning their friendship, but it did not work.

At the age of eighteen he entered the University of Cambridge to continue his studies. Newton never attended his classes regularly, as his main interest was the library. He graduated from Trinity College as a mediocre student due to his largely self-taught background, reading some of the most important books on mathematics and natural philosophy of the day.

At this time geometry and optics already had a fundamental role in Newton's life. In addition, in those days his fame began to grow, since he had initiated correspondence with the Royal Society.

Newton sent them some of his discoveries and a telescope, which aroused great interest among the members of the Society, but also criticism from some, mainly Robert Hooke.

That was the beginning of one of the many disputes he had in his scientific career.

It's considered that Newton showed aggressiveness towards his opponents, who were mainly Hooke, Leibniz and, religiously, the Catholic Church.

As president of the Royal Society, he was described as a cruel, vindictive and troublemaker dictator. However, it was a letter from Hooke, in which he commented on his intuitive ideas about gravity, that started his studies on mechanics and gravity fully.

Newton solved the problem that Hooke had not been able to and his results were written down in what many scientists believe to be the most important book in the history of science, Philosophiae naturalis principia mathematica.

In 1693 he suffered a great psychic crisis, causing long periods in which he remained isolated, during which he did not eat or sleep. At this time he suffered from depression and paranoia.

He corresponded with his friend, the philosopher John Locke, in which in addition to telling him about his bad condition, he accused him on several occasions of things he never did. Some historians believe that the crisis was caused by the breakdown of his relationship with his disciple Nicolás Fatio de Duillier. However, after the publication in 1979 of a study that showed a mercury concentration fifteen times higher than normal in Newton's hair, most believe that at this time Newton suffered from mercury poisoning when doing his alchemical experiments, which would explain your illness and changes in your behavior.

After writing the Principia he left Cambridge and moved to London, where he held various prestigious public positions, being appointed Provost of the King, Magistrate of Charterhouse and Director of the Mint.

His deepest interests included alchemy and religion, subjects on which his writings far surpass his scientific writings in volume. Among his religious opinions he defended Arianism and was convinced that the Holy Scriptures had been violated to support the Trinitarian doctrine.

This caused him serious problems when he was part of Trinity College in Cambridge and his religious ideas prevented him from being the director of the College. Among his alchemical studies were esoteric subjects such as the transmutation of the elements, the philosopher's stone, and the elixir of life.

From the end of 1664 he worked intensively on different mathematical problems. He then approached the binomial theorem, based on the work of John Wallis, and developed his own method called the calculus of fluxions. Shortly after, he returned to the family farm due to an epidemic of bubonic plague.

Retired with his family between 1665 and 1666, he experienced a very intense period of discoveries, among which the inverse square law of distance in gravitation stands out, his development of the bases of classical mechanics, the formalization of the method of fluxions and the generalization of the binomial theorem, also highlighting the physical nature of colors. However, he was silent for a long time about his discoveries in fear of criticism and the theft of his ideas. In 1667 he resumed his studies at the University of Cambridge.

From 1667 to 1670 he undertook research on optics and was elected a fellow of Trinity College. In 1669, his mentor, Isaac Barrow, resigned his Lucasian Chair of mathematics, a position in which Newton would succeed him until 1696.

The same year he sent John Collins, by means of Barrow, his Analysis per aequationes infinite terminorum numbers. For Newton, this manuscript represents the introduction to a powerful general method, which he would develop later: his differential and integral calculus.

Newton had discovered the principles of his differential and integral calculus around 1665-1666 and, over the next decade, developed at least three different approaches to his new analysis.

Newton and Leibniz staged a bitter controversy about the authorship of the development of this branch of mathematics.

Historians of science consider that both developed calculus independently, although Leibniz's notation was better and Newton's formulation was better applied to practical problems.

The controversy further divided British and Continental mathematicians. However, this separation was not so deep that Newton and Leibniz stopped exchanging results.

Newton approached the development of calculus from analytical geometry developing a geometric and analytical approach to mathematical derivatives applied to curves defined through equations. Newton was also looking for how to square different curves, and the relationship between quadrature and the theory of tangents.

After Roberval's studies, Newton realized that the tangent method could be used to obtain the instantaneous velocities of a known trajectory.

In his early investigations Newton dealt only with geometric problems, such as finding tangents, curvatures and areas using Descartes' analytical geometry as a mathematical basis. However, in an effort to separate his theory from that of Descartes, he began to work only with equations and their variables without having to resort to the Cartesian system.

After 1666 Newton gave up his mathematical works, and became increasingly interested in the study of nature and the creation of his Principia.

Between 1670 and 1672 he worked intensively on problems related to optics and the nature of light. Newton showed that white light was made up of a band of colors (red, orange, yellow, green, cyan, blue and violet) that could be separated by means of a prism.

As a consequence of these works, he concluded that any refracting telescope would suffer from a type of aberration known today as chromatic aberration, which consists of the dispersion of light in different colors when passing through a lens. To avoid this problem he invented a reflecting telescope (known as a Newtonian telescope).

His experiments on the nature of light led him to formulate his general theory about it, which, according to him, is made up of corpuscles and propagates in a straight line and not by means of waves.

The book in which he presented this theory was severely criticized by most of his contemporaries, including Hooke (1635-1703) and Huygens, who held different ideas defending an undulatory nature. These criticisms provoked his suspicion of the publications, so he retired to the solitude of his study in Cambridge.

In 1704, Newton wrote his most important work on optics, Opticks, in which he expounded his earlier theories and the corpuscular nature of light, as well as a detailed study of phenomena such as refraction, reflection, and scattering of light.

Although his ideas about the corpuscular nature of light were soon discredited in favor of the wave theory, later scientists came to the conclusion, thanks to the work of Max Planck and Albert Einstein, that light has a dual nature: it's wave and corpuscle at the same time. This is the foundation on which all quantum mechanics rests.

In 1687 he defended the rights of the University of Cambridge against the unpopular King James II, who tried to transform the university into a Catholic institution.

As a result of the efficiency that he demonstrated on that occasion, he was elected Member of Parliament in 1689, when the king was dethroned and forced into exile.

He held his seat for several years without being very active during the debates. During this time he continued his chemistry work. He also dedicated himself to the study of hydrostatics and hydrodynamics, in addition to building telescopes.

After having been a professor for nearly thirty years, Newton left his post to accept the responsibility of Director of the Currency in 1696. During this period he was a tireless persecutor of counterfeiters, whom he sent to the gallows, and proposed for the first time the use of gold as a monetary standard.

During the last thirty years of his life, he abandoned practically all scientific activity and gradually devoted himself to religious studies.

He was elected president of the Royal Society in 1703 and re-elected every year until his death. In 1705 he was knighted by Queen Anne, as a reward for his services to England. Even belonging to the Government and therefore being a rich man, around 1721 he ended up losing 20,000 pounds due to the bubble of the South Seas, before which he would say that 'I can predict the movement of the celestial bodies, but not the madness of the people'.

**Death**

The last years of his life were overshadowed by the unfortunate international controversy with Leibniz over the priority of inventing the new analysis.

During his old age, he suffered from various kidney problems, including excruciating renal colic, and after many hours of delirium, he died on the night of March 31, 1727. His remains were located in Westminster Abbey along with other men from England.