Isaac Newton

On Christmas Day, 1642, a boy was born in the manor house of Woolsthorpe, near Grantham, in Lincolnshire. He was born prematurely and was tiny, but he survived to become one of the greatest scientists the world has ever known.

NEWTON’S CHILDHOOD

Isaac Newton was named after his father, a farmer who had died a few months before Isaac was born. When Isaac was two years old, his mother Hannah married again. Isaac was brought up at Woolsthorpe by his grandmother. He did not like his mother’s remarriage and hated his stepfather, the Reverend Barnabus Smith.

His mother had three children by her second husband. When Isaac was 11, his stepfather died, and his mother, stepbrothers and sisters moved to live with him and his grandmother.

Isaac was sent to the Free Grammar School in Grantham. It was 8 kilometres from home, and he stayed with a family in the town. Isaac’s school reports were not very good and his mother thought he might be better off managing the farm. But Isaac did not get on too well with that either. Luckily, an uncle noticed his cleverness and love of learning. He persuaded Isaac’s mother to send him back to school. He also encouraged Isaac to go to university.

NEWTON GOES TO UNIVERSITY

In 1661 Newton entered Trinity College, at the University of Cambridge. He studied law, but he had a lot of freedom in his studies and he became interested in mathematics and astronomy. He read about the work of the astronomers Nicolaus Copernicus and Johannes Kepler, and worked through many mathematics books by himself. His mind was buzzing with ideas.

In 1665 the university was closed because of the Great Plague, which swept through southern England, killing thousands. Newton went home and for a year worked on mathematics and physics and developed his theory of gravity. This was probably the most creative time in his life.

NEWTON BECOMES A SCIENTIST

Back at the University of Cambridge, people began to recognize his ability. In 1669, at the age of just 27, he became a professor of mathematics there. For nearly 20 years, as well as giving lectures, Isaac Newton worked on his ideas in mathematics and physics. Many scientists admired his work. One was Edmond Halley, an important astronomer. Halley encouraged Newton to write up his work and publish it.

Newton needed the encouragement. He was a shy man, but could become angry if his work was criticized. He held long-lasting grudges. He did not publish his work for years because he was afraid it might be attacked.

In 1671 Newton was made a Fellow of the Royal Society—a society in London that only very important scientists are invited to join. He had been experimenting with light and told the Royal Society about his discoveries. Another important scientist belonging to the society, called Robert Hooke, did not agree with his ideas. Nor did the Dutch scientist Christiaan Huygens. Newton and Hooke became enemies, though they were polite in public.

In 1687 his friend Halley published Newton’s most famous work. It was written in Latin. It was called Philosophiae Naturalis Principia Mathematica, or Mathematical Principles of Natural Philosophy (science was called “natural philosophy” in those days). It is usually known as the Principia.

In this work, Newton described his theories about liquids and gases, and presented his theory of gravity. It was widely admired. But Hooke said that Newton had taken some of his ideas. Newton and Hooke continued their quarrel for years. Newton waited until Hooke died in 1703 before publishing his work on light.

Newton’s work on mathematics involved him in another argument. During the year he spent at home because of the plague, he had started to work on the mathematics of things that change. We now call this branch of mathematics calculus. Another famous scientist, Gottfried Leibniz, had come up with the same ideas a little later than Newton. They argued about who invented calculus first. The argument lasted until Leibniz died in 1716, and even after that.

All this anger and resentment led Newton to a nervous breakdown in 1678, and another in 1693. He turned away from people and shut himself away for long periods. Newton was deeply religious. Alongside his work in science, he pored over the Bible. He thought there were deep meanings hidden in its words. He was also fascinated by alchemy—the attempt to change different substances into gold.

MASTER OF THE MINT

Newton joined the Royal Mint in London in 1696. The Royal Mint makes the coins used as money. Three years later he became Master of the Mint and a rich man, but he never married, and he lived simply.

Newton was now 57 years old. For the rest of his life he was in charge of the Royal Mint. He also kept up his argument with Leibniz. In 1703 Newton became president of the Royal Society. Two years later he was knighted Sir Isaac Newton by Queen Anne.
Isaac Newton died in London on March 20, 1727, at the age of 85. He was the first scientist to be buried in Westminster Abbey.

WHAT WERE NEWTON’S ACHIEVEMENTS?

Isaac Newton is most famous for his theory of gravity. The story goes that he was sitting in the garden one day when he saw an apple fall from a tree. He wondered why it did not just float in the air instead of falling.

He realized that the force that made the apple fall to the ground was the same as the force that kept the Moon going round the Earth. He was able to describe the orbits of all the planets using this force—the force of gravity. But there were problems with his theory too. One basic problem was that Newton never really explained gravity. He just said that any two masses pull each other.
The problems were only solved many years later, in the 20th century, when Albert Einstein worked out his Theory of General Relativity. But Newton’s theory was good at describing the way objects fall and how planets orbit the Sun. We still use it for many things.

Newton also showed that white light is a mixture of all the colours of the rainbow. He used a prism to split white light into its separate colours. He made many other studies of light. Newton believed that light is a stream of particles. Other scientists agreed with Christiaan Huygens that light must be a wave. Now we know that Newton was not wrong—light acts as both a particle and a wave.
Newton’s interest in light came from his efforts to make a good telescope. He invented a reflecting telescope, which used mirrors instead of lenses, in 1668. We call them Newtonian telescopes.

He also invented the mathematical method of calculus. Though Leibniz invented the same method, Newton had thought of it earlier. We now use calculus as a basic tool in many problems in science and mathematics.

Newton’s Principia is often described as the greatest scientific work ever written. It seems hard to believe that one person could achieve so much. Newton could be difficult, and sometimes unpleasant, but he devoted his life to searching for truth and he knew that there was a great deal more to learn. He wrote:

“To myself, I seem to have been only like a boy playing on the seashore, and diverting myself in now and then finding a smoother pebble or a prettier shell than ordinary, whilst the great ocean of truth lay all undiscovered before me.”

Did you know?

• In addition to being a great scientist, Isaac Newton was also a Member of Parliament. He tried to prevent King James II from turning the universities into Catholic institutions and was elected Member of Parliament for the University of Cambridge in 1689 to make sure that this did not happen.
• Isaac Newton was a deeply religious man and he devoted a great deal of his time to investigating religion. In fact he owned more books on that subject than he did on science. He also sought to find evidence in the Bible for much of the mythology of Ancient Greece.
• Some people today have accused Isaac Newton of trying to destroy the reputation of the scientist Robert Hooke, with whom he had lots of arguments. Although no real evidence supports this, many believe that some of Newton's great scientific ideas were actually those of Hooke.