Who Was Isaac Newton?

by Janet Pascal

  Chapter 9

  Newton’s Big Book

  Halley’s question rekindled Newton’s interest in the way planets moved. He wrote a nine-page essay to answer it and then kept on going. “Now that I am upon this subject,” he wrote, “I would gladly know the bottom of it.” In only eighteen months, he finished his five-hundred-page masterpiece. The title is Mathematical Principles of Natural Philosophy, familiarly known from its Latin title as Principia. With this book, he laid the foundation of modern physics. Every physicist since 1687 has built their work on the ideas in Newton’s book.

  Halley was excited. He wanted to make sure Newton didn’t keep this revolutionary work to himself. He acted as Newton’s editor and even paid for the book to be printed.

  Right away, it looked as if there might be trouble. Newton’s old enemy, Hooke, claimed that Newton had taken ideas from him. Newton was so furious that he threatened not to publish at all. It took all Halley’s tact to calm him down.

  The book came out in 1687 and caused a sensation. Readers felt as if the universe had suddenly been explained to them. A French mathematician wondered, “Does Mr. Newton eat, drink, and sleep like other men?” (As we know, the answer to this was actually no.)

  Probably the book was admired and discussed more than it was actually read. It was almost impossible to follow. Newton even hinted that he had done this deliberately. It was a way to protect himself from people asking stupid questions.

  Newton’s book made him so famous that he was elected to Parliament. He became a member of the government just in time to vote in favor of the Glorious Revolution of 1689. Except for this one important vote, which brought a new king to the throne of England, he did not take any active role in Parliament. The only time he actually spoke was to ask for a window to be closed.

  Chapter 10

  Laws of Motion

  Over three hundred years after Newton’s book was written, it is hard to understand how great its impact has been. The things he figured out now seem natural and obvious to us. This is because Newton completely changed the way people think. Today, even people who have never heard of Newton think of movement in the terms he invented.

  What exactly was in his revolutionary book? The idea of gravity, to start with. Earlier, Newton had studied two forces. The first was the one that pulled the apple and the moon toward the Earth. The second was the one that made planets orbit the sun. He realized that these were both the same force. He gave it the name we still use today: “It is now established that this force is gravity, and therefore we shall call it gravity from now on.”

  Newton also created his three laws of motion. He had learned the first law from Galileo. It says that if something is moving, it will keep moving until something makes it stop. If something is sitting still, it won’t move until some force makes it move.

  The second law shows how much force is needed to make something move or stop moving.

  The final law says that, “For every action there is an equal and opposite reaction.” This means that every time you push on something, it pushes back just as strongly, but in the opposite direction.

  If you’re standing on a skateboard and you push against the ground, the ground pushes back against you, which is why the skateboard moves forward. Or think of a balloon filled with air. If you let go of the neck of the balloon, the air rushes out of the balloon backward.

  This pushes the balloon forward with the same force, so the balloon flies through the air. This same principle makes a rocket’s engine work.

  Newton’s three laws explain the movement of everything in the universe. When combined with a lot of mathematics, these laws can predict everything from tides on Earth to the movement of stars in distant galaxies.

  One odd thing is missing from Newton’s explanation of gravity. Although he described how gravity acts, he never said exactly what it is. We can’t blame him for this—three hundred years later, we still don’t really know.

  Chapter 11

  Becoming a Legend

  After his book came out, Newton became legendary. Suddenly Cambridge students saw him in a whole new way. “We gaz’d on him . . . as on someone divine,” one recalled.

  His life, however, continued more or less unchanged for the next few years. Then in 1693, Newton had a mental breakdown. He couldn’t eat or sleep. He wrote his friends strange letters saying he wished they were dead. He accused them of trying to get him in trouble with women.

  When he recovered, he decided he needed a change. In 1696, he asked some powerful friends to help him find a new job. They arranged for him to help run the Royal Mint.

  The Mint was the place that created all England’s coins. It was in the Tower of London.Newton moved into a grand house in London. His friends expected he would hire someone else to do most of the work. Instead, Newton threw himself into the job.

  For years, counterfeiters had been clipping bits of silver off the edges of coins to make new coins. By Newton’s time, much of England’s money was worth less than it was supposed to be. The government had to do something. They decided on the Great Recoinage of 1696.

  The Mint collected all the clipped coins and remade them into a new form of coin. These coins had ridged edges, so they were harder to fake. Newton oversaw the whole thing. He did such a good job that in 1699 he was promoted to Master of the Mint. He stayed in this position for almost thirty years, until he died.

  Once the Great Recoinage was done, Newton turned his attention to catching counterfeiters. He made himself into a kind of detective with a network of spies and informers. His greatest triumph was the capture of the clever counterfeiter named Chaloner. Newton pursued him for years and finally succeeded in having him executed.

  During his first few years in London, Newton kept his distance from the Royal Society. He didn’t want any more fights. In 1703, his old enemy Hooke died. The president of the society died the same year. Newton was immediately elected in his place. In 1704, Newton finally published his theory of optics. The book was based on research from many years earlier, but as he explained, “To avoid being engaged in Disputes about these matters, I have hitherto delayed the printing.” He meant that he had waited until Hooke was dead.

  Chapter 12

  Battles at the Royal Society

  Newton ruled the Royal Society like a tyrant. This led to some ugly incidents. The worst was the fight about who really invented calculus. Newton had created his form of calculus, the method of fluxions, as early as 1665, but he had refused to publish it. Only a few carefully chosen people got the chance to see it.

  Around 1675, a German mathematician named Gottfried Leibniz had come up with a similar system, which he called calculus. It isn’t surprising that someone else would make the same discovery as Newton had. After all, Leibniz had been working on the same kinds of problems. He had even written to Newton about his new kind of mathematics. (Ironically, he began one letter, “How great I think the debt owed you . . .”) Leibniz published his paper on calculus in 1684.

  At first, there didn’t seem to be a problem. Then in 1704, Newton finally published his version of calculus. An anonymous reviewer hinted that he might have borrowed some of Leibniz’s ideas.

  Newton was furious. He didn’t want anyone else to get the credit for inventing calculus. An ugly battle began, with Newton accusing Leibniz of stealing ideas from him. At first Leibniz was reasonable. “Mr. Newton developed it further, but I arrived at it by another way,” he wrote to a friend. “One man makes one contribution, another man another.”

  Newton didn’t think this made any difference. “Second inventors,” he claimed, “have no right.”

  Finally in 1711, Leibniz appealed to the Royal Society to settle the fight, but Newton was president of the society. He put himself in charge of the committee looking into the issue. What’s more, he secretly wrote the committee’s report himself.

  Published in
1713, the report twisted the evidence to make it seem that Leibniz had stolen Newton’s work. Leibniz died three years later. Newton never regretted what he had done. Years later, he recalled happily that he “had broke Leibniz’s Heart.”

  In one sense, however, Leibniz won the calculus wars. Newton’s method of fluxions was a kind of personal shorthand. He never meant it to be used by anyone else. Leibniz’s system was easier for other people to understand. Everyone who learns calculus today uses Leibniz’s terms, symbols, and methods, not Newton’s. Even the name calculus is from Leibniz. If Newton knew, he would be furious.

  Chapter 13

  Genius

  Despite being so frail as a baby, Newton lived to be an old man. By his last years he was wealthy, powerful, and respected. In 1705, he was knighted by Queen Anne. He became Sir Isaac Newton.

  Newton’s mind remained sharp and his health mostly good almost to the end. He led a meeting of the Royal Society less than a month before his death.

  He died on March 20, 1727, at age eighty-five. He was buried in London’s Westminster Abbey—the first scientist to receive such an honor. The inscription on his fancy marble monument shows what awe he inspired. “Here is buried Isaac Newton, Knight, who by a strength of mind almost divine . . . explored . . . what no other scholar has previously imagined.” The great poet Alexander Pope wrote of him: “Nature and Nature’s Laws lay hid in Night. God said, ‘Let Newton be!’ and all was light.”

  A mind almost divine—this is a grand claim. Still, scientists from Newton’s time through our own agree. What Newton accomplished was greater than his individual discoveries. He wanted to understand how everything fit together. It was as if other scholars had written interesting sentences, but Newton figured out the way all these sentences could be put together to tell the story of how the universe worked.

  WESTMINSTER ABBEY

  BUILDING STARTED ON WESTMINSTER ABBEY IN THE YEAR 1245. KINGS, QUEENS, AND THEIR FAMILIES ARE USUALLY MARRIED AND CROWNED THERE. UNTIL THE 1760S, IT WAS ALSO WHERE MOST OF THEM WERE BURIED. PEOPLE WHO WORKED FOR THE CHURCH WERE ALSO BURIED THERE. STARTING AROUND THE TIME NEWTON WAS A CHILD, BEING BURIED IN WESTMINSTER ABBEY BECAME A WAY TO HONOR SOMEONE FOR SPECIAL ACHIEVEMENTS. GREAT GENERALS, POLITICIANS, POETS, AND MUSICIANS WERE RECOGNIZED IN THIS WAY. ISAAC NEWTON WAS THE FIRST SCIENTIST.

  Newton knew that he had only begun to tell this story. As an old man he said, “I don’t know what I may seem to the world, but as to myself, I seem to have been only like a boy playing on the sea-shore 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.”

  For the next two hundred years, almost all physics had its roots in his ideas. Only at the beginning of the twentieth century did another great genius—Albert Einstein—discover the limits of Newton’s discoveries. In day-to-day life, however, people rarely have to deal with situations where Newton’s physics doesn’t make sense. It’s still the way we understand the world. Whether we are riding a bicycle, catching a baseball, or dropping an apple, most of us most think of movement in terms we learned from that strange, bad-tempered, brilliant loner Isaac Newton.

  TIMELINE OF ISAAC NEWTON’S LIFE

  1642-Isaac Newton is born on December 25

  1654-Moves to a nearby town to attend grammar school

  1661-Enters Trinity College, Cambridge

  1665-Graduates from Cambridge with a BA Moves back to his mother’s farm to escape the plague

  1668-Receives his master’s degree from Cambridge

  1669-Becomes Lucasian Professor of Mathematics

  1671-Sends his reflecting telescope to the Royal Society

  1672-Elected to the Royal Society

  1679-Newton’s mother, Hannah, dies

  1684-Halley, Hooke, and Wren meet at a coffeehouse to discuss planetary motion

  1687-Newton’s Principia published

  1689-Elected to Parliament

  1693-Suffers a nervous breakdown.

  1696-Moves to London to work at the Mint

  1699-Appointed Master of the Mint

  1703-Elected President of the Royal Society

  1704-Publishes his research on optics

  1705-Knighted

  1712-The Royal Society establishes a committee to decide who invented calculus

  1727-Isaac Newton dies, March 20

  TIMELINE OF THE WORLD

  1642-Civil war breaks out in England

  1648-The Thirty Years’ War ends in Europe

  1649-King Charles I beheaded, January 30

  1660-Charles II restored as king of England Royal Society founded

  1663-Robert Hooke invents the word “cell” to describe what he sees in the microscope

  1665-Plague breaks out in England

  1666-Great Fire of London

  1667-Milton publishes Paradise Lost

  1670-Charleston (originally called Charles Towne) is founded in North America by the British

  1675-Pocket watch invented

  1682-Halley’s comet appears

  1688-1689-Glorious Revolution in England

  1689-A bill of rights guarantees Englishmen some freedom of speech and religion

  1692-The Salem witch trials take place in Massachusetts

  1694-The Bank of England is established

  1706-Benjamin Franklin is born

  1709-The “Great Frost” is the coldest winter in Europe in over five hundred years

  1712-First practical steam engine built

  1727-Janet Horne becomes the last person in Britain to be executed as a witch

  BIBLIOGRAPHY

  Ackroyd, Peter. Newton. New York: Doubleday, 2006.

  * Christianson, Gale E. Isaac Newton and the Scientific Revolution. New York: Oxford University Press, 1996.

  Gleick, James. Isaac Newton. New York: Pantheon Books, 2003.

  * Krull, Kathleen. Giants of Science: Isaac Newton. New York: Viking, 2006.

  Westfall, Richard S. The Life of Isaac Newton. New York: Cambridge University Press, 1993.

  * Books for young readers