1.166511month, and establish the forward serial number method (differential); In May of the following year, the inverse flow number method (integral) was established. The establishment of calculus was praised by Engels as one of the three major discoveries of mathematics in17th century.

2. 1666, Newton bought a glass prism and began to study the dispersion phenomenon. Without a laboratory, he darkened his room in the country, made a small hole in the window board to let a proper amount of sunlight into the room, and put a prism on the window hole, through which the light refracted to the opposite wall. Newton observed on the wall: a colored light band several times longer than the original white light spot. Finally, it is concluded that white light itself is a heterogeneous mixture of colored lights with different degrees of refraction, which is Newton's theory of colored light, that is, the principle of colored light.

3. 1666, Newton began to study gravity again. It is said that Newton was reading a book under a tree and saw an apple fall to the ground, but he realized that the earth had gravity on the apple. He also extended this theory of gravity to the orbit of the moon, and deduced from Kepler's law that the force that keeps the planets in orbit must be inversely proportional to the square of their distance from the center of rotation. This is the prototype of the well-known law of gravity. law of universal gravitation