The Life Of Isaac Newton And His Contributions To Science

Isaac Newton was born on December 25th 1642 in Woolsthorpe, Lincolnshire, England. He was a mathematician, physician, astronomer, theologian and author who is widely recognized as one of the most influential scientists of all time, and a key figure in the scientific revolution. Newton made discoveries in optics, motion and mathematics. Newton theorized that white light was a composite of all colours of the spectrum, and that light was composed of particles. His momentous book on physics, Principia, contains information on nearly all of the essential concepts of physics except energy, ultimately helping him to explain the laws of motion and the theory of gravity. Along with mathematician Gottfried Wilhelm von Leibniz, Newton is credited for developing essential theories of calculus.

Legend has it that, when he returned home from university, Newton experienced his famous inspiration of gravity with the falling apple. According to this common myth, Newton was sitting under an apple tree when a fruit fell and hit him on the head, inspiring him to come up with the theory of gravity. While there is no evidence that the apple actually hit Newton on the head, he did see an apple fall from a tree, leading him to wonder why it fell straight down and not at an angle. Consequently, he began exploring the theories of motion and gravity.

In 1687 Newton published Mathematical Principles of Natural Philosophy, most often known as Principia. It is said to be the single most influential book on physics and possibly all of science. Its publication immediately raised Newton to international prominence. Principia offers an exact quantitative description of bodies in motion, with three basic laws of motion. Newton was three basic laws of motion outlined in Principia helped him arrive at his theory of gravity. Toward the end of this life, Newton lived at Cranbury Park, near Winchester, England, with his niece, Catherine (Barton) Conduitt, and her husband, John Conduitt. By this time, Newton had become one of the most famous men in Europe. His scientific discoveries were unchallenged. He also had become wealthy, investing his sizable income wisely and bestowing sizable gifts to charity. Despite his fame, Newton's life was far from perfect: He never married or made many friends, and in his later years, a combination of pride, insecurity and side trips on peculiar scientific inquiries led even some of his few friends to worry about his mental stability. By the time he reached 80 years of age, Newton was experiencing digestion problems and had to drastically change his diet and mobility. In March 1727, Newton experienced severe pain in his abdomen and blacked out, never to regain consciousness. He died the next day, on March 31 1727, at the age of 84.

The early life of Isaac Newton

Sir Isaac Newton was born at Woolsthorpe, in Lincolnshire, about six miles south of Grantham, on the 4th January 1643. His father, Mr Isaac Newton, died at the early age of thirty-six, only a few months after his marriage to Harriet Ayscough. This lady was accordingly left in a state of pregnancy and appears to have given a premature birth to her only child. The undersized infant was expected to be dead in the next few minutes, however, he stayed alive. When Newton was three, his mother remarried and went to live with her new husband, the Reverend Barnabas Smith, leaving her son in the care of his maternal grandmother, Margery Ayscough.

When he reached his twelfth year he went to the public school at Grantham, taught by Mr Stokes, and was boarded at the house of Mr Clark, an apothecary in that town. According to information which Sir Isaac himself gave to Mr Conduit, he seems to have been very inattentive in his studies and very low in the school. However, one day an incident occurred when a boy who was above him kicked him in the stomach. Isaac, motivated by the pain, stayed determined to become a better student than him, and he hadn’t stopped until he became the best student in the school. During the hours of play, when the other boys were occupied with their amusements, his mind was engrossed with mechanical contrivances. The principal pieces of mechanism which he thus constructed were a windmill, a water clock, and a carriage put in motion by the person who sat in it. When a windmill was erecting near Grantham on the road to Gunnerby, Isaac frequently attended the operations of the workmen and acquired such a thorough knowledge of the machinery that he completed a working model of it, which excited universal admiration. This model was frequently placed on the top of the house in which he lodged at Grantham, and was put in motion by the action of the wind upon its sails. His water clock was formed out of a box and was proportional to a common house clock.

The index of the dial plate was turned by a piece of wood, which either fell or rose by the action of water dropping. His mechanical carriage was a vehicle with four wheels, which was put in motion with a handle wrought by the person who sat in it. Isaac took great pleasure in entertaining his schoolfellows with amusements of scientific character. He introduced flying kites to his school, he made paper lanterns which he used when going to school in early winter mornings and he frequently attached these lanterns to the tails of his kites in a dark night to aspire the country people with the belief that they were comets. In the house where he lived there were some female whose company he enjoyed thoroughly. One of these girls, Miss Storey, was two or three years younger than Isaac. He preferred spending time with this young lady and her friends over his schoolfellows, and their favourite occupation was constructing small tables and cupboards. Isaac shared the house with Miss Storey for almost 6 years, and although there are reasons to believe their friendship could’ve been more, it never happened, mostly because of him focusing on other priorities.

Among the early passions of Newton, we must recount his love of drawing and of writing verses. His room was furnished with pictures drawn, coloured, and framed by himself, sometimes from copies, but often from life. In 1656 his mother was widowed again, so she took up her residence in Woolsthorpe with her three children, Isaac’s step-siblings, Mary, Benjamin, and Hannah Smith. Newton was now fifteen years old and had made great progress in his studies, but considering his age he was thought of as capable for farm management and country business at Woolsthorpe, so his mother recalled him from the Grantham School. His mother would soon figure out that her son was not destined to cultivate soil, and considering his passion for study, and dislike for every other occupation, she wisely decided to send him back to Grantham school, where he continued for some months in busy preparation for his academic studies.

It was on the 5th of June 1660, in the 18th year of his age, that Newton was admitted into Trinity College, Cambridge. As a young mind thirsty for knowledge, Newton was very excited for the transition from a small village to a university like that of Cambridge. At that time the lessons taught were mainly based on Aristotle’s teachings, but Isaac preferred learning about modern philosophers such as Rene Descartes, and astronomers like Galileo Galilei, Nicolaus Copernicus and Johannes Kepler. We do not know about his progress in the first three years of his studies, although it is known that he bought a prism in 1664 to examine Descartes' theory of colours which he proved to be wrong later on. In the books of the university, Newton is recorded as having been admitted sub-sizer in 1661. He became a scholar in 1664. In 1665 he took his degree of Bachelor of Arts, and in 1666, in consequence of the breaking out of the plague, he retired to Woolsthorpe. That year, while back home with his mother, he was sitting alone in the garden, reflecting on the nature of gravity. The legend says that he saw an apple fall down from a tree and started wondering why it always goes straight down, and not upwards, or at an angle. He realized that a force gravity, pulls objects towards the centre of the Earth. The question wasn’t whether gravity exists, but how strong is it, and whether the reason that Moon stays in Earth’s orbit. He started working and discovering on that topic, and had devoted the majority of life doing research in fields of motion and gravity. Later that same year, 1666, Newton returned to Trinity College. In 1667, he was made Junior Fellow. In 1668, he took his degree of Master of Arts, and in the same year, he was appointed to a Senior Fellowship.

Isaac Newton’s contribution to physics

Sir Isaac Newton is one of the most influential scientists of all time and his research and discoveries were a key figure to the scientific revolution. Other than physics, Newton largely contributed to development in mathematics, astronomy, alchemy, natural philosophy and Christian theology.

Motion and gravity

In the 1660s Newton studied the motion of colliding bodies and deduced that the centre of mass of two colliding bodies remains in uniform motion. Surviving manuscripts of the 1660s also show Newton's interest in planetary motion and by 1669 he had shown, for a circular case of planetary motion, that the force he called 'endeavour to recede' (now called centrifugal force) had an inverse-square relation with distance from the centre. In 1687, after 18 months of effective and non-stop work, Newton published Philosophiae Naturalis Principia Mathematica (Mathematical Principles of Natural Philosophy), most often known as the Principia. The Principia states Newton's laws of motion, forming the foundation of classical mechanics; Newton's law of universal gravitation; and a derivation of Kepler's laws of planetary motion. The Principia is considered one of the most important works in the history of science.

The three laws of motion

Newton’s laws of motion are: A stationary body will stay stationary unless an external force is applied to it Force is equal to mass times acceleration, and a change in motion (i. e. , change in speed) is proportional to the force applied. For every action, there is an equal and opposite reaction. Newton's first law states that every object will remain at rest or in uniform motion in a straight line unless compelled to change its state by the action of an external force. This is normally taken as the definition of inertia. The key point here is that if there is no net force acting on an object (if all the external forces cancel each other out) then the object will maintain a constant velocity. If that velocity is zero, then the object remains at rest. If an external force is applied, the velocity will change because of the force. The second law explains how the velocity of an object changes when it is subjected to an external force. The law defines a force to be equal to change in momentum (mass times velocity) per change in time. Newton also developed the calculus of mathematics, and the 'changes' expressed in the second law are most accurately defined in differential forms. (Calculus can also be used to determine the velocity and location variations experienced by an object subjected to an external force. ) For an object with a constant mass m, the second law states that the force F is the product of an object's mass and its acceleration a: F = m * a. The third law states that for every action (force) in nature there is an equal and opposite reaction. In other words, if object A exerts a force on object B, then object B also exerts an equal force on object A. Notice that the forces are exerted on different objects. These laws helped explain not only elliptical planetary orbits but also nearly every other motion in the universe; how the planets are kept in orbit by the pull of the sun’s gravity; how the moon revolves around Earth and the moons of Jupiter revolve around it; and how comets revolve in elliptical orbits around the sun. They also allowed him to calculate the mass of each planet, calculate the flattening of the Earth at the poles and the bulge at the equator, and how the gravitational pull of the sun and moon create the Earth’s tides. In Newton's account, gravity kept the universe balanced, made it work, and brought heaven and Earth together in one great equation.

The law of universal gravitation

In astronomy, Kepler's laws of planetary motion are three scientific laws describing the motion of planets around the Sun. The orbit of a planet is an ellipse with the Sun as one of the two foci. A line segment joining a planet and the Sun sweeps out equal areas during equal intervals of time. The square of the orbital period of a planet is proportional to the cube of the semi-major axis of its orbit.

The fact that heavy bodies have always a tendency to fall to the earth, no matter at what height they are placed above the Earth's surface, seems to have led Newton to conjecture that it was possible that the same tendency to fall to the earth was the cause by which the moon was retained in its orbit around the earth. Newton, by calculating from Kepler's laws, and supposing the orbits of the planets to circle around the sun in the centre, had already proved that the force of the Sun acting upon the different planets must vary as the inverse square of the distances of the planets from the sun. He therefore was led to inquire whether, if the Earth's attraction extended to the Moon, the force at that distance would be of the exact magnitude necessary to retain the Moon in its orbit. But by observing the distance through which a body would fall in one second of time at the Earth's surface, and by calculating from that on the supposition of the force diminishing in the ratio of the inverse square of the distance, he found that the Earth's attraction at the distance of the moon would draw a body through 15 ft. (4. 57 meters) in one minute. Newton regarded the discrepancy between the results as a proof of the inaccuracy of his conjecture and laid aside at that time any further thoughts of this matter. The law of universal later appears in 1687, in Newton’s book Principia. It states that every point mass attracts every other point mass by a force acting along the line intersecting the two points. The force is proportional to the product of the two masses and inversely proportional to the square of the distance between them. The equation of universal gravitation is F=Gm1m2r2 where F is the gravitational force acting between two objects, m1 and m2 are the masses of the objects, r is the distance between the centres of their masses, and G is the gravitational constant.


In 1666, Newton observed that the spectrum of colours exiting a prism in the position of minimum deviation is oblong, even when the light ray entering the prism is circular, which is to say, the prism refracts different colours by different angles. This led him to conclude that colour is a property intrinsic to light - a point which had been debated in prior years. From 1670 to 1672, Newton lectured on optics. During this period he investigated the refraction of light, demonstrating that the multicoloured spectrum produced by a prism could be recomposed into white light by a lens and a second prism. He showed that coloured light does not change its properties by separating out a coloured beam and shining it on various objects and that regardless of whether reflected, scattered, or transmitted, the light remains the same colour. Thus, he observed that colour is the result of objects interacting with already-coloured light rather than objects generating the colour themselves. This is known as Newton's theory of colour.

The Newtonian telescope

From his research, he concluded that the lens of any refracting telescope would suffer from chromatic aberration. To prove the concept, he used reflective mirrors as objectives instead of lenses to bypass the problem. Building the design, he faced the problem of suitable mirror material and shaping technique. Newton ground his own mirrors out of a custom composition of highly reflective speculum metal.

In late 1668, he managed to make the world’s first functioning reflecting telescope, known as Newtonian telescope. He chose a spherical shape for his mirror instead of a parabola to simplify construction; even though it would introduce spherical aberration, it would still correct chromatic aberration. He added to his reflector what is the hallmark of the design of a Newtonian telescope, a secondary diagonally mounted mirror near the primary mirror's focus to reflect the image at a 90° angle to an eyepiece mounted on the side of the telescope.

This unique addition allowed the image to be viewed with minimal obstruction of the objective mirror. He also made the tube, mount, and fittings. Newton's first version had a primary mirror diameter of 33mm and a focal ratio of f/5.


Newton argued that light is composed of particles or corpuscles, which were refracted by accelerating into a denser medium. In 1704, Newton published Opticks, in which he expounded his corpuscular theory of light. Opticks was different from Principia but in some ways, they were rivalling. The publication of Opticks represented a major contribution to science, it was largely a record of experiments and the deductions made from them, covering a wide range of topics in what was later to be known as physical optics. In this book, there are records on experiments on dispersion, separation of light into a spectrum of its component colours. He demonstrates how the appearance of colour arises from selective absorption, reflection, or transmission of the various component parts of the incident light. The biggest achievement of this book is that it disproved Aristotle’s and Theophrastus theory that pure light is white, or even colourless, and is altered into colour by mixture with darkness caused by interactions with matter. Newton showed the exact opposite light is composed of different spectral hues (red, orange, yellow, green, blue, indigo and violet), and all colours, even white, are formed by various mixtures of these hues. He states that colour is a mind-made sensation and not a property of objects or light itself. Newtonian science became a central issue in the assault waged by the philosophes in the Age of Enlightenment against a natural philosophy based on the authority of ancient Greek or Roman naturalists or on deductive reasoning from first principles (the method advocated by French philosopher Rene Descartes), rather than on the application of mathematical reasoning to experience or experiment. Voltaire popularised Newtonian science, including the content of both the Principia and the Opticks, in his Elements de la philosophie de Newton (1738).

Later life and death

During the period of 1692/93, Newton suffered a nervous breakdown and was in a depressive state for the next 18 months. He suffered insomnia and poor digestion, and in his letters to friends, he was showing signs of irrationality. Newton recorded in his notebook of experimenting with chemicals during June 1693. The limited evidence for symptomatic mental illness of Newton during this period stems from correspondences (c. f. The Royal Society) revealing melancholia, desire for withdrawal from relations including his good friends, insomnia, apathy, loss of appetite, the delusion of persecution, possible failures in memory (amnesia), and bipolarity. He was also a member of the Parliament of England for Cambridge University from 1689 to 1701, but according to some accounts he didn’t contribute much and wasn’t particularly useful. Later works - The Chronology of Ancient Kingdoms Amended (1728) and Observations Upon the Prophecies of Daniel and the Apocalypse of St. John (1733) - were published after his death. He also devoted a great deal of time to alchemy. In April 1705, Queen Anne knighted Newton during a royal visit to Trinity College, Cambridge. As a result of a report written by Newton on 21 September 1717, Britain effectively moved from the silver standard to the gold standard. It is still not clear whether he did this intentionally or not.


In the 1690s, Newton wrote a number of religious tracts regarding the literal and symbolic interpretations of the Bible. One of the most remarkable of Newton's theological works is his Historical Account of Two Notable Corruptions of the Scriptures. Sir Isaac Newton was very anxious for its publication because it deprived the Trinitarians of two passages in favour of the Trinity, and he was worried about possible consequences. It was first published in 1754. Scholars long debated whether Newton disputed the doctrine of the Trinity. His first biographer, Sir David Brewster, who compiled his manuscripts, interpreted Newton as questioning the veracity of some passages used to support the Trinity, but never denying the doctrine of the Trinity as such. In the twentieth century, encrypted manuscripts written by Newton and bought by John Maynard Keynes (among others) were deciphered and it became known that Newton didn’t believe in Trinity.


Towards the end of his life, Newton took up a residence in Cranbury Park with his niece and husband Catherine Barton Conduitt and John Conduitt. In his old age, Isaac was a largely generous person. He lived in a luxurious style, with three male and female servants. He was very hospitable and kind, even in his house. His diet was frugal and his clothes were always simple. He spent a considerable amount of money to relieve the poor, and the amounts of money he donated sometimes were enormous. However, for the last couple of years of his life, Newton was so absent minded that he even forgot to eat, and at times it was necessary to remind him to have a meal. As a consequence of poor diet, sleep deprivation, alchemy experiments and overall horrible health, Sir Isaac Newton died in his sleep in London, on March 20th 1727. He was buried in Westminster Abbey. He divested most of his estate to his relatives, and his papers went to John Conduitt and Catherine Barton. After his death, Newton's hair was examined and found to contain mercury, probably resulting from his alchemical pursuits. Mercury poisoning could explain Newton's eccentricity and mental health issues in late life. Although it was claimed that he was once engaged, Newton never married. The French writer and philosopher Voltaire, who was in London at the time of Newton's funeral, said that he 'was never sensible to any passion, was not subject to the common frailties of mankind, nor had any commerce with women a circumstance which was assured me by the physician and surgeon who attended him in his last moments'


Isaac Newton's fame grew even more after his death, as many of his contemporaries proclaimed him the greatest genius who ever lived. Maybe a slight exaggeration, but his discoveries had a large impact on Western thought, leading to comparisons to the likes of Plato, Aristotle and Galileo. Although his discoveries were among many made during the Scientific Revolution, Isaac Newton's universal principles of gravity found no parallels in science at the time. Of course, Newton was proven wrong on some of his key assumptions. In the 20th century, Albert Einstein would overturn Newton's concept of the universe, stating that space, distance and motion were not absolute but relative and that the universe was more fantastic than Newton had ever conceived. Newton might not have been surprised; in his later life, when asked for an assessment of his achievements, he replied, 'I do not know what I may appear to the world, in the same year but to myself I seem to have been only like a boy playing on the seashore, and diverting myself now and then in finding a smoother pebble or prettier shell than ordinary, while the great ocean of truth lay all undiscovered before me. '

10 October 2020
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