How did Newton discover the theory of universal gravitation?

1643 65438+1October 4th, Newton was born in a farmer's family in Wolthorpe, Lincolnshire, England. Newton was a premature baby, weighing only 3 pounds at birth. The midwife and his relatives are worried about whether he will survive. But no one expected that this seemingly insignificant little thing would become a scientific giant in the future and live to be 85 years old.

Three months before Newton was born, his father died. When he was two years old, his mother remarried to a priest and left Newton to his grandmother. 1 1 years old, my mother's step hubband passed away, and my mother returned to Newton with a son and two daughters born with step hubband. Newton Newton was taciturn and stubborn since childhood, which may come from his family situation.

From about the age of five, Newton was sent to public schools. Newton was not a child prodigy when he was a teenager. He has average qualifications and average grades, but he likes reading books and books introducing various simple mechanical model making methods, from which he is inspired. He likes to make some strange gadgets by himself, such as windmills, wooden clocks, folding lanterns and so on.

Legend has it that young Newton made a model of the mill after thoroughly understanding the mechanical principle of the windmill. He tied the mouse to a treadmill with wheels, and then put a corn in front of the wheel, just out of the mouse's reach. The mouse wants to eat corn, so it keeps running, so the wheel keeps turning; Once when he was flying a kite, he hung a small lamp on the rope. In the evening, the villagers looked shocked and suspected that there was a comet. He also made a small water clock. Every morning, the water bell will automatically drop water on his face to wake him up. He also likes painting and carving, especially carving sundials. His sundial was placed in the corner of his house and everywhere on the windowsill to observe the movement of the shadow.

Newton entered Grantham Middle School not far from home at the age of 12. Newton's mother had hoped that he would become a farmer, but Newton himself had no intention of doing so and loved reading. As he grew older, Newton became more and more fond of reading, meditating and doing small scientific experiments. When he was studying in Grantham Middle School, he lived in a pharmacist's house, which influenced him by chemical experiments.

Newton's academic performance in middle school is not outstanding, but he just loves reading and is curious about natural phenomena, such as colors, the movements of the four seasons, especially geometry, Heliocentrism of Copernicus and so on. He also takes reading notes in different categories and likes to do gadgets, tricks, inventions and experiments in an ingenious way.

16 1 year, 19-year-old Newton entered Trinity College of Cambridge University as a tuition fee waiver, and paid the tuition fee by doing chores for the college. 1664 became a scholarship winner, and 1665 received a bachelor's degree.

Because Newton was influenced and influenced by mathematics and natural science in Cambridge, he had a strong interest in exploring natural phenomena, and the quiet environment in his hometown made his thoughts spread their wings and fly. The short period from 1665 to 1666 became the golden age of Newton's scientific career. He is full of thinking in the field of natural science, brilliant and productive, thinking about problems that his predecessors have never thought about, stepping into fields that his predecessors have never set foot in, and creating unprecedented amazing achievements. The legend that Newton didn't realize gravity until he saw the apple fall to the ground was also an anecdote that happened at this time.

Before Newton, astronomy was the most prominent subject. But why do planets have to orbit the sun according to certain rules? Astronomers cannot fully explain this problem. The discovery of gravity shows that the movements of stars in the sky and objects on the ground are governed by the same law-mechanical law.

Long before Newton discovered the law of gravity, many scientists had seriously considered this problem. For example, Kepler realized that there must be a force at work that makes the planet move along an elliptical orbit. He thinks this force is similar to magnetic force, just as a magnet attracts iron. 1659, Huygens found that a centripetal force was needed to keep the object moving in a circular orbit by studying the movement of the pendulum. Hooke and others thought it was gravity, and tried to deduce the relationship between gravity and distance.

In Harley 1664, Hooke discovered that the orbit bending of comets when they approached the sun was the result of the sun's gravity. 1673, huygens deduced the law of centripetal force; 1679, Hooke and Halley deduced from centripetal force law and Kepler's third law that the gravitational force for maintaining planetary motion is inversely proportional to the square of distance.

Newton himself recalled that around 1666, he had considered the problem of gravity when he lived in his hometown. The most famous saying is that Newton often sits in the garden for a while during holidays. Once, as it happened many times before, an apple fell from the tree. ...

The accidental landing of an apple is a turning point in the history of human thought, which opens the mind of the person sitting in the garden and causes him to ponder: What is the reason why almost all objects are attracted by the center of the earth? Newton mused. Finally, he discovered the gravity which is of epoch-making significance to mankind.

Newton's genius lies in that he solved the mathematical argument problem that Hooke and others could not solve. 1679, Hooke wrote to Newton and asked him if he could prove that the planet moves in an elliptical orbit according to the law of centripetal force and the law that gravity is inversely proportional to the square of distance. Newton didn't answer the question. 1685, when Harley visited Newton, Newton had discovered the law of universal gravitation: there is gravitation between two objects, which is inversely proportional to the square of the distance and directly proportional to the product of the masses of the two objects.

At that time, accurate data such as radius of the earth and the distance between the sun and the earth were available for calculation. Newton proved to Harley that the gravity of the earth is the centripetal force that makes the moon move around the earth, and also proved that the planetary motion conforms to Kepler's three laws of motion under the action of solar gravity.

At the urging of Harley, at the end of 1686, Newton wrote an epoch-making masterpiece, Mathematical Principles of Natural Philosophy. The Royal Society is short of funds to publish this book. Later, one of the greatest works in the history of science was published in 1687 with Harley's support.

In this book, from the basic concepts of mechanics (mass, momentum, inertia, force) and basic laws (three laws of motion), Newton not only demonstrated the law of universal gravitation mathematically, but also established classical mechanics as a complete and rigorous system, unified celestial mechanics with ground object mechanics, and realized the first large-scale synthesis in the history of physics.

With the improvement of scientific reputation, Newton's political status has also been rapidly improved. 1689 was elected as a representative of the National Congress University. As a congressman, Newton gradually began to alienate the science that brought him great achievements. From time to time, he expresses his disgust at the field he represents. At the same time, he spent a lot of time arguing with Hooke, Leibniz and other famous contemporary scientists about the priority of science.

Newton lived a superior life in London in his later years. 1705, he was made an aristocrat by Queen Anne. Newton was very rich at this time and was generally regarded as the greatest scientist alive. He was the chairman of the Royal Society. During his twenty-four years in office, he ruled the society with an iron fist. No one can be elected without his consent.

1727 On March 20th, the great isaac newton passed away. Like many other outstanding Englishmen, he was buried in Westminster Abbey. His tombstone is engraved with the words: Let people cheer, such a great human once existed brilliantly in this world.

More than 280 years later, many anecdotes about Newton are still circulating among the people. It is said that Newton was often too busy to be slovenly, and often walked into the university cafeteria without a tie, garter or breeches. On one occasion, when he proposed to a girl, his thoughts were confused again, leaving only an infinite binomial theorem in his mind. He grabbed the girl's finger, mistook it for a pipe, and forced it into the pipe, causing the girl to leave him screaming. Newton never got married because of this.

Newton took his time to observe the little things in daily life and made great discoveries in the history of science. However, in life, he is sloppy and has made many jokes. On one occasion, he boiled eggs while reading a book. When he opened the pot to eat eggs, he found a pocket watch in the pot. On another occasion, he invited a friend to dinner. When the meal was ready, Newton suddenly thought of a problem and went into the back room alone. My friend waited for him for a long time, but he didn't come out. My friend ate all the chicken by himself and left the chicken bones on the plate without saying goodbye. Newton remembered and came out to see the bones on the plate. He thought he had eaten them, so he turned back to the back room and continued to study his problems.

Learning point

Halley

Harley, English astronomer and mathematician. He is a professor of geometry at Oxford University and the second director of Greenwich Observatory. Born in the era of scientific revolution based on new ideas, Harley entered Queen's College of Oxford University on 1673. 1676, I went to St. Helena in the South Atlantic, determined the orientation of the stars in the southern sky, completed the southern catalog with the exact position of 34 1 star, recorded a transit of mercury, and made a lot of pendulum observations (the pendulum in the southern hemisphere swung in the opposite direction to that in the northern hemisphere). Harley also discovered the self-motion of Sirius, Nanhesan and Dajiao, and the long-term acceleration of the moon.