Before Newton, Mozi, Bacon, Da Vinci and others all studied optical phenomena. The law of reflection is one of the optical laws that people have long known. When modern science rose, Galileo discovered a "new universe" through a telescope, which shocked the world. Dutch mathematician Hans sneer first discovered the law of refraction of light. Descartes proposed the particle of light. ...

Newton and his contemporaries, such as Hooke and Huygens, studied optics with great interest and enthusiasm, just like Galileo and Descartes. 1666, when Newton was on vacation at home, he got a prism, and he made a famous dispersion experiment with this prism. After a beam of sunlight passes through a prism, it is decomposed into several color spectral bands. Newton blocked the light of other colors with a slit baffle, and only let the light of one color pass through the second prism, resulting in only the light of the same color. In this way, he found that white light is composed of different colors of light, which is the first major contribution.

In order to verify this discovery, Newton tried to combine several different monochromatic lights into white light, and calculated the refractive index of different colors of light, which accurately explained the dispersion phenomenon. The mystery of the color of matter has been solved. It turns out that the color of matter is caused by the different reflectivity and refractive index of different colors of light on the object. In A.D. 1672, Newton published his research results in the Journal of Philosophy of the Royal Society, which was his first paper.

Many people study optics in order to improve refractive telescopes. Newton discovered the composition of white light and thought that the dispersion phenomenon of refractive telescope lenses could not be eliminated (later, some people eliminated the dispersion phenomenon with lenses made of glass with different refractive indexes), so he designed and manufactured reflective telescopes.

Newton was not only good at mathematical calculation, but also able to make all kinds of experimental equipment and do fine experiments by himself. In order to make a telescope, he designed a grinding and polishing machine and tested various grinding materials. 1668, he made the first prototype of reflective telescope, which is the second largest contribution. 167 1 year, Newton presented the improved reflective telescope to the royal society, which made him famous and was elected as a member of the royal society. Reflecting telescope's invention laid the foundation of modern large-scale optical astronomical telescope.

At the same time, Newton also carried out a lot of observation experiments and mathematical calculations, such as studying the abnormal refraction phenomenon of glacier stone discovered by Huygens, the color phenomenon of soap bubbles discovered by Hooke, the optical phenomenon of Newton's ring and so on.

Newton also put forward the "particle theory" of light, thinking that light is formed by particles and takes the fastest straight-line motion path. His "particle theory" and Huygens' "wave theory" later formed two basic theories about light. In addition, he also made Newton color wheel and other optical instruments.

Newton's achievements

Newton is a master of classical mechanical theory. He systematically summarized the work of Galileo, Kepler and Huygens, and got the famous laws of gravity and Newton's three laws of motion.

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.

1664, Hooke found that when comets approached the sun, their orbits were curved due to 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.