Sir Isaac Newton (Jan. 4, 1643–March 31, 1727) was a superstar of physics, math, and astronomy even in his own time. He occupied the chair of Lucasian Professor of Mathematics at the University of Cambridge in England, the same role later filled, centuries later, by Stephen Hawking. Newton conceived of several laws of motion, influential mathematical principals which, to this day, scientists use to explain how the universe works.

### Fast Facts: Sir Isaac Newton

**Known For**: Developed laws that explain how the universe works**Born**: Jan. 4, 1643 in Lincolnshire, England**Parents**: Isaac Newton, Hannah Ayscough**Died**: March 20, 1727 in Middlesex, England**Education**: Trinity College, Cambridge (B.A., 1665)**Published Works**:*De Analysi per Aequationes Numero Terminorum Infinitas*(1669, published 1711),*Philosophiae Naturalis Principia Mathematica*(1687),*Opticks*(1704)**Awards and Honors**: Fellowship of the Royal Society (1672), Knight Bachelor (1705)**Notable Quote**: "If I have seen further than others, it is by standing upon the shoulders of giants."

## Early Years and Influences

Newton was born in 1642 in a manor house in Lincolnshire, England. His father had died two months before his birth. When Newton was 3 his mother remarried and he remained with his grandmother. He was not interested in the family farm, so he was sent to Cambridge University to study.

Newton was born just a short time after the death of Galileo, one of the greatest scientists of all time. Galileo had proved that the planets revolve around the sun, not the earth as people thought at the time. Newton was very interested in the discoveries of Galileo and others. Newton thought the universe worked like a machine and that a few simple laws governed it. Like Galileo, he realized that mathematics was the way to explain and prove those laws.

## Laws of Motion

Newton formulated laws of motion and gravitation. These laws are math formulas that explain how objects move when a force acts on them. Newton published his most famous book, "Principia," in 1687 while he was a mathematics professor at Trinity College in Cambridge. In "Principia," Newton explained three basic laws that govern the way objects move. He also described his theory of gravity, the force that causes things to fall down. Newton then used his laws to show that the planets revolve around the suns in orbits that are oval, not round.

The three laws are often called Newton’s Laws. The first law states that an object that is not being pushed or pulled by some force will stay still or will keep moving in a straight line at a steady speed. For example, if someone is riding a bike and jumps off before the bike is stopped, what happens? The bike continues on until it falls over. The tendency of an object to remain still or keep moving in a straight line at a steady speed is called inertia.

The second law explains how a force acts on an object. An object accelerates in the direction the force is moving it. If someone gets on a bike and pushes the pedals forward, the bike will begin to move. If someone gives the bike a push from behind, the bike will speed up. If the rider pushes back on the pedals, the bike will slow down. If the rider turns the handlebars, the bike will change direction.

The third law states that if an object is pushed or pulled, it will push or pull equally in the opposite direction. If someone lifts a heavy box, they use force to push it up. The box is heavy because it is producing an equal force downward on the lifter’s arms. The weight is transferred through the lifter’s legs to the floor. The floor also presses upward with an equal force. If the floor pushed back with less force, the person lifting the box would fall through the floor. If it pushed back with more force, the lifter would fly up in the air.

## Importance of Gravity

When most people think of Newton, they think of him sitting under an apple tree observing an apple fall to the ground. When he saw the apple fall, Newton began to think about a specific kind of motion called gravity. Newton understood that gravity was a force of attraction between two objects. He also understood that an object with more matter or mass exerted the greater force or pulled smaller objects toward it. That meant that the large mass of the Earth pulled objects toward it. That is why the apple fell down instead of up and why people don’t float in the air.

He also thought that maybe gravity was not just limited to the Earth and the objects on the earth. What if gravity extended to the Moon and beyond? Newton calculated the force needed to keep the Moon moving around the earth. Then he compared it with the force that made the apple fall downward. After allowing for the fact that the Moon is much farther from the Earth and has a much greater mass, he discovered that the forces were the same and that the Moon is also held in orbit around Earth by the pull of earth’s gravity.

## Disputes in Later Years and Death

Newton moved to London in 1696 to accept the position of warden of the Royal Mint. For many years afterward, he argued with Robert Hooke over who had actually discovered the connection between elliptical orbits and the inverse square law, a dispute that ended only with Hooke's death in 1703.

In 1705, Queen Anne bestowed a knighthood upon Newton, and thereafter he was known as Sir Isaac Newton. He continued his work, particularly in mathematics. This led to another dispute in 1709, this time with German mathematician Gottfried Leibniz. They both quarreled over which of them had invented calculus.

One reason for Newton's disputes with other scientists was his overwhelming fear of criticism, which led him to write, but then postpone publication of, his brilliant articles until after another scientist created similar work. Besides his earlier writings, "De Analysi" (which didn't see publication until 1711) and "Principia" (published in 1687), Newton's publications included "Optics" (published in 1704), "The Universal Arithmetic" (published in 1707), the "Lectiones Opticae" (published in 1729), the "Method of Fluxions" (published in 1736), and the "Geometrica Analytica" (printed in 1779).

On March 20, 1727, Newton died near London. He was buried in Westminster Abbey, the first scientist to receive this honor.

## Legacy

Newton’s calculations changed the way people understood the universe. Prior to Newton, no one had been able to explain why the planets stayed in their orbits. What held them in place? People had thought that the planets were held in place by an invisible shield. Newton proved that they were held in place by the sun’s gravity and that the force of gravity was affected by distance and mass. While he was not the first person to understand that the orbit of a planet was elongated like an oval, he was the first to explain how it worked.

## Sources

- “Isaac Newton's Life.”
*Isaac Newton Institute for Mathematical Sciences.* - “Isaac Newton Quotes.”
*BrainyQuote*, Xplore. - “Sir Isaac Newton.”
*StarChild*, NASA.