1643 65438+1October 4th (julian calendar1642 65438+February 25th) Newton was born in a yeoman's family in Ursp, Lincolnshire, England. Newton's father died before he was born. Newton was born weak. Newton was taciturn and stubborn from childhood. This habit may come from his family situation. Newton liked to play mechanical tricks when he was a teenager. Legend has it that he made a model of a mill, driven by a little mouse; Once when he was flying a kite, he hung a small lamp on the rope. In the evening, the villagers were surprised to find that a comet appeared. He likes painting and carving, especially carving sundials. The sundial he carved was placed in every corner of his house and on the windowsill to check the movement of the shadow and know the time. /kloc-at the age of 0/2, he entered Granger Middle School not far from home. Newton's mother had hoped that he would become a farmer and support his family, but Newton himself had no such plan, and he loved reading so much that he often forgot to work. 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 and was influenced by chemical experiments. Newton's academic performance in middle school is not outstanding, but he 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 notes on reading experiences in different categories, and likes to make gadgets, tricks, inventions and experiments in an ingenious way. At that time, English society was infiltrated by Protestant ideas, and two relatives of Newton's family were priests, which may affect Newton's religious life in his later years. From these ordinary environments and activities, we can't see that Newton is a gifted child. However, J Stokes, the headmaster of Grantham Middle School, and W Ayscough, Newton's uncle who was a priest, showed great insight and encouraged Newton to go to college. Newton entered Trinity College of Cambridge University as a fee-reducing student on 166 1, became a scholarship winner on 1664, and received his bachelor's degree on 1665. /kloc-In the mid-7th century, the education system of Cambridge University was still saturated with a strong flavor of medieval scholasticism. When Newton entered Cambridge University, there were still some scholastic courses, such as logic, classical Chinese, grammar, ancient history, theology and so on. Two years later, Trinity College took on a new look. H Lucas created a unique lecture, which stipulated that natural science knowledge such as geography, physics, astronomy and mathematics should be taught. The first professor of the lecture, I barrow, is a learned scientist. It was this teacher who led Newton to natural science. In this learning process, Newton mastered arithmetic and trigonometry and learned Euclid's geometric principles. He also read Kepler's Optics, Descartes' Principles of Geometry and Philosophy, Galileo's Two World Systems, R. Hooke's Micro Atlas, History of the Royal Society and Journal of Early Philosophy. Newton studied under Barrow's door, which was the key period of his study. Barrow is older than Newton 12 years old. He is good at maths and optics. He admired Newton's talent very much. He thinks Newton can surpass himself in mathematics. 1665 ~ 1666 London plague. Cambridge is not far from London, and the school is closed for fear of infection. Newton returned to his hometown Thorpe in June 1665.

Because Newton was influenced and cultivated by mathematics and natural science in Cambridge, he was very interested in exploring natural phenomena. During the two years from 1665 to 1666, he was full of thinking in the field of natural science, brilliant, and came forth in large numbers, thinking about problems that his predecessors had never thought about, stepping into fields that his predecessors had never set foot in, and creating unprecedented amazing achievements. At the beginning of 1665, he established the approximation method of series and the law of transforming binomial with arbitrary power into series. In June of the same year 165438+ 10, the forward serial number method (differential) was established; In June of the following year, I studied color theory; In May, I began to study the reverse flow number method (integral). In this year, Newton also began to think about gravity and wanted to extend the theory of gravity to the orbit of the moon. He also 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. 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. In a word, during his two years in his hometown, Newton engaged in scientific creation with more vigorous energy than before and cared about natural philosophy. It can be seen that Newton's great scientific thoughts in his life were conceived, germinated and formed in his short two years of youth and keen thinking.

Newton returned to Cambridge University in 1667, and was selected as the companion of Trinity College Middle School in June 1 2007, and was selected as the companion of primary school in March 16 the following year. Barrow had a full understanding of Newton's talent at that time. 1669101On October 27th, Barrow asked Newton, who was only 26 years old, to replace him as the professor of Lucas Lecture. Newton gave his lectures on optics (1670 ~ 1672), arithmetic and algebra (1673 ~ 1683), mathematical principles of natural philosophy (hereinafter referred to as principles) Part I (1684 ~ 653). From 172, he was elected as the president of the Royal Society. During this period, Newton had the most correspondence with scientists at home and abroad, such as R. Boyle, J. Collins, J. Framsted, D. Gregorian, E. Harley, Hook, C. Huygens, G.W.F F. von Leibniz and J. Wallis. After writing Principles, Newton was tired of being a university professor. With the help of C. montague, an aristocratic descendant he met in college, Newton got the position of supervisor of the Mint Bureau in 1696, was promoted to director in 1699, and resigned from Cambridge University in 170 1. At that time, the British monetary system was chaotic, and Newton used his knowledge of metallurgy to make new coins. He was knighted on 1705 for his contribution to the reform of the currency system. In his later years, he studied religion and wrote "Historical Textual Research on Two Major Errors in the Bible". Newton died in Kensington Palace, a suburb of London, on March 3rd1,1727 (julian calendar 20th) and was buried in Westminster Abbey, London.

The invention of "optics" and reflective telescope, like optics and mechanics, was valued in ancient Greece. In order to meet the needs of astronomical observation, the manufacture of optical instruments was developed very early. The law of light reflection was well known as early as Euclid's time, but the law of refraction was not discovered by Dutch scientist W Snell until shortly before Newton was born. The production of glass has spread from Arabia to western Europe. /kloc-in the 0/6th century, the handicraft industry of grinding lenses in the Netherlands flourished. Microscopes or telescopes can be made by properly combining lenses into a system. The invention of these two instruments played an important role in the development of science. Before Newton, Galileo first made astronomical observations with his telescope. Cangue telescope is a kind of telescope with convergent lens as eyepiece and divergent lens as objective lens. There is also the popular Kepler telescope consisting of two converging lenses. Neither telescope can eliminate the dispersion of the objective lens. Newton invented a mirror made of metal as an objective lens instead of a converging lens, thus avoiding the dispersion of the objective lens. At that time, the telescope made by Newton was 6 inches long, with a diameter of 1 inch and a magnification of 30 ~ 40 times. After improvement, in 167 1 year, he made a second larger reflecting telescope and sent it to the Royal Society for review. This telescope was collected as a precious scientific relic by the Royal Society. In order to make a reflective telescope, Newton personally melted the alloy and ground the mirror. Newton liked to make models and do experiments by hand since he was a child, which was of great help to the success of his optical experiments. As early as BC, people were speculating about the color of light, linking the color of rainbow with the color formed by the edge of glass sheet. From Aristotle to Descartes, it is believed that white light is pure and uniform, which is the essence of light, while colored light is only a variant of light. None of them did the experiment as seriously as Newton.

About 1663, Newton began to be keen on optical research, during which he ground glass and made telescopes. 1666, he bought a glass prism and began to study the dispersion phenomenon. To this end, Newton wrote in his book Optics: "Make my room dark, open a small hole in my window board, let a proper amount of sunlight enter the room, put my prism at the entrance, and the light will be refracted through the prism to reach the opposite wall." Newton saw a colored light band on the wall, which was several times longer than the original white light spot. He realized that these colors were the original colors that made up white light. In order to prove this, Newton made further experiments. A small hole is also made on the screen where the light band is projected, so that part of the color in the light band passes through the second small hole, is refracted by the second prism placed behind the screen, and is projected on the second screen. The first prism rotates slowly around its axis, and only the image that passes through the second small hole and falls on the second screen moves up and down with the rotation of the first prism. So we can see that the blue light refracted the most by the first prism is also refracted the most by the second prism. On the contrary, red light is refracted by the front and rear prisms at least. So Newton came to the conclusion: "The rectangular colored light band obtained by refraction of the first prism is just white light composed of different colors of light." In other words: "White light itself is an uneven mixture of colored light with different degrees of refraction." This is Newton's theory of light and color. It was established through experiments, which Newton called "key experiments". This experiment can be said to be the basis for J.von Fraunhofer to establish spectroscopy a century and a half later. In fact, Newton's optical proposition No.4, 1 ~ 2 inches long, has only11or 1/20 inches wide rectangular holes instead of small round holes. He said that the results were clearer than before, but there was no record of Flawn Hough Line. After doing a lot of experiments in this field, Newton sent his conclusion to the Royal Society for review on 1672. Unexpectedly, it caused a heated debate. Huygens was against him, and Hooke especially attacked him. As early as 1665, Hooke put forward the wave theory of light in Britain, which is only a hypothesis. Huygens made it complete, thinking that the ether in space is everywhere. He regarded the ether as a vibrating medium, and regarded every particle of the medium as a center, forming a wave around the center. Huygens successfully used this physical image to explain the reflection and refraction of light, and also used it to study the birefringence of Iceland spar (but the establishment of light wave theory needs to be proved by the interference experiment of T. Young in Britain a century and a half later). Newton, on the other hand, said that the biggest obstacle of wave theory is that it cannot explain the straight line of light. He proposed that luminous objects emit particles moving in a straight line, and the particle flow impacts the retina, causing vision. It can also explain the refraction and reflection of light, and even after modification, it can also explain the phenomenon of "diffraction" discovered by F.M. grimaldi. But Newton admitted that the particle theory is not as clear as the wave theory in explaining the color of thin films. At that time, the debate between particle theory and wave theory was very fierce, and the debate between the two sides lasted for many years. At that time, the debate between light particle theory and wave theory can be summarized by quoting E.T. Whitaker's words: "When A. Einstein explained the photoelectric effect with M. Planck's quantum principle, the idea of light particles was reborn in 1905 after a century of silence, and the basic principle of light quantum existence was obtained. His thoughts have been fully affirmed by experiments, especially the Compton effect produced by the collision between photons and electrons obeys the classical laws of collision mechanics. At the same time, the experiment on the fluctuation of light has not failed, so we have to admit that the fluctuation theory and the particle hypothesis are correct. " There is no doubt that Newton's Optics is not only a masterpiece of physics, but also his Principles, and it is also a classic of science. The first edition of Optics was printed in 1704 and came out after Hooke's death. In the last part of optics, a famous list of "problems" is attached in a unique form, and * * * puts forward 3 1 problem (the first edition puts forward 16 problem). In the "problem", not only the refraction and reflection of light, but also the problems of light and vacuum, even gravity and celestial bodies. He talked about the fluctuation of light and the interaction between sunlight and matter in many places, which involved many aspects of physics and was very enlightening. Later generations commented that these "problems" are the most important part of optics, not empty talk. Newton established the theory of light with the help of experimental results and analysis in his book Optics. However, the book did not mention that different glasses have different refractive indexes, and there was no achromatic experiment in the book, probably because he had not got the prisms of different glasses at that time. But Newton made a reflective telescope to avoid the dispersion of the objective lens, but it was a wonderful method. So far, the manufacture of large telescopes has followed this method. Three years after Newton's death (1730), Newton's revised 4th edition of Optics was published. 193 1 The popular version is reproduced in the fourth edition.

Einstein said in the preface of the second edition of 193 1 Newton's optics: "Newton's time has long been forgotten ... Newton's discovery has entered a recognized treasure house of knowledge. Nevertheless, this new edition of his optical works should be welcomed by our heartfelt gratitude, because only this book can let us have the honor to see the great man's own activities. "

According to the law of universal gravitation and the mathematical principle of natural philosophy, the Danish astronomer Tycho observed the planets orbiting the sun for many years in the16th century. After his death, the German astronomer Kepler sorted out and analyzed Tycho's observation records for 20 years, and summarized the famous Kepler's three laws of planetary motion. This discovery not only laid the foundation for classical astronomy, but also led to the discovery of the law of universal gravitation. Before Kepler came to the three laws of planetary motion, he put forward the viewpoint of gravity between the sun and the planets in 1596; Then the problem of centrifugal force when an object moves in a circle is put forward. It is generally believed that Galileo has understood centrifugal force, but further understanding and calculation of it remains to be done by Newton. 1664 65438+1On October 20th, Newton had put forward a concrete method of how to calculate the centripetal force of an object when it moves in a circle in his Computational Herbs. Newton wrote the derivation and calculation method in detail in the first part of his Principles (3rd edition), Chapter 2, Proposition 4, Theorem 4 and the following inference 1, clearly pointing out: "Therefore, since these arcs represent the speed of a moving object, the centripetal force is the square of this speed divided by the circumferential radius." It can be seen that the derivation of distance inverse square law is inseparable from the calculation of centripetal force. By the way, the centrifugal force equation derived by Huygens in different ways is similar to Newton's, and the result is published in 1673. Although Newton put forward the method of seeking centripetal force in his early book "Computational Herbs", he himself said that "the centrifugal force theory published by Mr. Huygens later, I believe before me". It is worth noting that in the first and third parts of the Principles, Newton never mentioned the word centrifugal force when referring to orbital operation, but always emphasized the centripetal force pulling to the center of the orbit.

About the law that gravity is inversely proportional to the square of distance, the debate about the right of invention was recorded in history at that time. Some people think that the distance inverse square law can be directly derived from Kepler's third law, but this law cannot be derived without the concept and movement of centripetal force. The concept and operation of centripetal force were first put forward by Newton. Hook, seven years older than Newton, claimed that he had long known that gravity was inversely proportional to the square of distance, but he could not prove it. When The Principle 1 was printed, Hooke asked Newton to share the invention right of this law through Harley. Newton refused. In the annotation under the above proposition 4 of Principles (3rd edition), when it is mentioned that inverse square law is suitable for celestial movement, Newton said, "Sir Ryan, Dr Hooke and Dr Harley have all paid attention to it respectively." At the same time, it is also mentioned that "Mr. Huygens compared gravity to the centrifugal force of a rotating body in his excellent book" The Swing of the Pendulum ". In this way, people learned something about the invention from inverse square law. Some people think that in 1666, Newton tried to calculate the gravity between the moon and the earth with the length of 1 degree on the great arc of the earth's surface as 60 miles; Through actual calculation, the moon's cycle around the earth is inconsistent with reality, so the draft is abandoned. 1682, Newton learned that the longitude of J. Picard's earth was 1 degree and the length was 69. 1 mile, so he recalculated it to make the calculation consistent with the actual observation. Newton unified the gravity seen in daily life with celestial gravity, which is of great significance in the history of science. What is the orbit of the planet around the sun? This was the concern of the scientific community at that time. The publication of the answer to this question is closely related to the publication of the principle, which has been vividly recorded in the history of science. 1684 65438+ 10 C. Ryan, Harley and Hook, three famous British scientists at that time, discussed the orbits of planets in London. Hook is familiar with this, but he can't figure out the calculation result. So Newton's good friend Harley made a special trip to Cambridge to consult Newton. Newton told Harley that he had calculated and affirmed that the orbit of the planet around the sun was elliptical; However, after years of pressure, the manuscript was still not found, so I promised to recalculate and submit it in about 3 months. Harley visited Cambridge again as promised, and Newton handed over a manuscript on sports, which Harley greatly appreciated. Newton wrote another book on the basis of this manuscript, On the Motion of Objects, which was sent to the Royal Society in February 1684. The first part of this book mainly corresponds to the first and second parts of the later Principles. The rest becomes the third part of the principle. Harley urged Newton to write the book "Principles" and publish it publicly. He paid for the printing and personally supervised the school. 1 in July, 687, the e-naturalism principle of philosophy1was published. Newton started thinking and sketching from 1664, and it has been 23 years now. The second edition of Principles was published in 17 13, and the third edition was published in 1725 (see the title page of Newton's masterpiece Principles (1686)). The Principles were originally written in Latin. Two years after Newton's death, it was translated into English by A. Mott and published, which is now the popular English version of Principles. There are two important parts before the first part of the principle. The first part is the definition. There are eight definitions, five of which are about centripetal force. He said that the forces acting on objects come from different sources, such as impact, pressure and centripetal force. The word centripetal force was invented by Newton (on another occasion, Huygens called it the supplement of centrifugal force). Newton has a long explanation in the chapter on definition. In his explanation, he mentioned an imaginary experiment: "When firing artillery shells on high mountains, the artillery force was insufficient, and the artillery shells flew for a while, and then fell to the ground in an arc curve. "If the gun is powerful enough, the shell will revolve around the earth, which is a manifestation of centripetal force." Today, the idea of artificial satellite had already appeared in Newton's mind. In the chapter of definition, Newton expounded his concept of absolute time and space. He chose the names absolute space and absolute time for the familiar space and time. Newton believed that absolute motion can only be perceived in absolute space, especially when the object rotates. At that time, Huygens and British Archbishop Becker questioned this. In any case, this short chapter expresses Newton's basic views on force and time and space, and is an important original document for studying Newton.

Before the first part, in addition to defining a chapter, there is also a chapter about axioms or theorems of motion. In this chapter, Newton expounded three famous laws of motion (see Newton's laws of motion). The first law of motion is generally called the law of inertia, which is generally thought to have been expounded by Galileo and Descartes. In order to change the direction (or speed) of an object, there must be external forces, and the concept of mass will inevitably arise. The basic concept of mass (the quantity of original matter) was first put forward by Newton in the definition chapter of the first part of Principles and became one of the most basic concepts in physics. He clearly distinguished between mass and weight, and expounded the relationship between the two quantities in various environments. In mechanics, Newton used mass to express the characteristics of objects. Einstein pointed out: "Only by introducing a new concept of mass can he (Newton) relate force to acceleration." Newton also defined the word momentum. Newton pointed out that momentum is a measure of the motion of matter, which connects matter and motion; Dual matter, dual momentum; Material and sports have doubled; The momentum is four times that of the original. Then the conservation of momentum is expounded. Newton has seven inferences after the three laws of motion, in which it is discussed that when two forces act on an object at the same time, the acceleration direction of the object and the synthesis of the forces are on the diagonal of the parallelogram of the two forces. After that, there was a long explanation, which generally discussed the relationship between the three laws of motion, and also used the elastic collision and inelastic collision experiments of two pendulums to illustrate the conservation of motion and the relationship between the second law and the third law. As can be seen from the above, Newton's three laws of motion are not discrete, but related. Newton used collision experiments to study force in calculus herbs in his early years, and he emphasized that "impulse" is the concept of force in his principle. Later, this concept was developed, saying that a series of pulses with infinitely short gaps became a continuous force. This sentence contains

Definition of expressive force in differential form. Newton assumes that a particle moves in inertia on a straight line, and this particle is connected to a point outside the straight line. In the same time, the area swept by this line must be equal; If an external force is encountered at a certain point on a straight line, the particle will move in the direction between the original direction of the particle and the direction of the external force. Newton finally proved that a moving particle is subjected to an external force at a fixed point by the method of infinitesimal concept limit. If the external force is on the straight line between the particle and the fixed point, and the force is inversely proportional to the square of the distance, then the trajectory of the particle is likely to be an ellipse, and this fixed point is the focus of the ellipse. Here, Newton concluded that the area swept by the straight line between the planet and the sun must be proportional to time. Newton also imagined that a particle runs from a point on an ellipse for an infinitely short time, and the distance from the particle to the tangent in a very short time is inversely proportional to the square of the distance from the focus to the point. When two points on the ellipse are close, Newton concludes that Kepler's area law is the key condition in this extreme case. In a word, Newton concluded that if the area law holds, the elliptical orbit means that the force pointing to the focus must be inversely proportional to the square of the distance. Newton then deliberately proved that the area law is a necessary and sufficient condition for the force acting on a moving object to point to the center. This reveals the importance of Kepler's first and second laws. The second part of the Principle discusses the motion of particles in the medium with resistance (gas and liquid). Newton used more mathematical methods here, but the physical meaning was less than before. In the first part, Newton tried his best to prove the existence of gravity (centripetal force) in the universe by various methods; In the second part, Newton assumed that the resistance in the medium is proportional to the speed of the object; It is also assumed that it is proportional to the square of velocity; It is even considered that part is the ratio of speed and part is the ratio of the square of speed. He also demonstrated some other problems. In these works, Newton used mathematical skills to deal with some seemingly meaningless problems. He also studied the elasticity and compressibility of gases. In the second part of the Principle, Newton measured the relationship between the weight (that is, the gravity of the earth) and the inertia through the movement experiment placed in the fluid. In classical physics, these two quantities can only be determined by experiments. The study of acoustics is recorded in the second part of Principles. Newton studied the speed of sound in theory (see Theorems 48, 49 and 50), and the results obtained were 65,438+06% lower than the measured values. He believes that the speed of sound is directly proportional to the square root of the so-called "elasticity" and inversely proportional to the square root of the medium density. Newton also studied the form of sound propagation. He said that propagation is caused by the pulsation of air, and pointed out that the pulsation of waves is only the alternating motion of particles in the medium, which is no different from the motion of a pendulum. In the last paragraph of the second part, Newton clarified that the vortex hypothesis has nothing to do with celestial motion. Newton wanted to write the third part of Principles as a general summary. But later changed the plan, titled "Cosmic System". In this part, the motion of planets, satellites and comets in the solar system and the generation of ocean tides are discussed. He called these forces gravity, which is what we call gravity today. He explained that gravity is the interaction between two objects. The sun attracts the planet to make it run in orbit, and the planet also exerts force on the sun, which is stipulated by the third law of motion. It's just that the mass difference between the sun and the planets is too big, and the movement of the sun is very small. The motion between planets is disturbed by gravity, which is called perturbation in many-body problems. In the third part, Newton expounded the perturbation of the sun to the moon and Saturn to Jupiter. In the third part, taking Kepler's third law as an example, the distance of Jupiter satellite and its operating period are calculated.

The Great Comet appeared twice in 1680, 165438+ 10 and16865438+March. Newton initially thought it was two different comets moving in a straight line, but in opposite directions. Framstead reminded Newton through observation that it was just the same comet, orbiting the sun. So Newton calculated that the comet of 1680 moves parabolically with the sun as the focus, and its centripetal force to the sun also obeys the distance inverse square law. 1695, Halley assumed that the orbit of comet 1680 was a flat and long ellipse orbiting the sun. Harley and Newton recalculated this. In the third part of the second and third editions of Principles, there are detailed observation records and calculations, and it is predicted that this comet will orbit the sun once in about 75 years, which is today's famous Halley's comet (the earliest record of this comet in China is BC 1057). Finally, Newton said in his conclusion that "the comet is one of the planets, and it has a great eccentricity when it orbits the sun", but he also said that "the orbit of the comet on the parabola can be determined by three observations".

When we talk about Newton's physics, we can't help but mention his great contribution to mathematics. The full name of principle is the mathematical principle of natural philosophy. At that time, the so-called natural philosophy included physics, chemistry and so on, but mainly physics. As mentioned above, the center of the first and second parts is to clarify the law of motion of objects by mathematical methods, which shows the important position of mathematics in the principle. When readers first read Principles, they often think that the author advocates Euclid's geometric norms in ancient Greece when writing. But after careful reading, we can find that the author takes the form of geometry, which has a brand-new connotation in essence. After establishing the geometric conditions, the author immediately introduced some so-called limit methods that were carefully defined. This method is based on a universal limit operation principle, which is different from classical ancient Greek geometry. The limit theory is introduced in detail in the lemma and explanation of 1 1 in the first chapter of the principle. There is a detailed explanation of the meaning of limit: there are two interdependent physical quantities. When the two quantities become smaller, Newton calls it the flow number, and its ratio is also changing gradually. When the independent variable reaches infinity, the ratio reaches a limit, which Newton called flow. This is called derivative or WeChat business. Newton found his rheology very useful. Conversely, this technique can find a surface surrounded by curves, which is now called integration. The first part of Chapter 8 Proposition 4 1 is the application of integral. It can be said that the central content of the book Principles is to discuss Newton's great creation in mathematics, namely calculus, and to apply this creation to solve celestial motion and other related physical problems. Historians also attribute the invention of calculus to Leibniz. For this great invention in mathematics, Newton and Leibniz came first, and later theorists followed. Even then, the two sides also exchanged letters on this issue, which has been controversial. Listen to how Einstein praised Newton's differential discovery. He said, "Only the form of differential law can fully meet the requirements of modern physicists for the law of cause and effect. The clear concept of differential law is one of Newton's greatest intellectual achievements. "

Newton's important contribution in his life is to collect the achievements of scientific pioneers in 16 and 17 centuries, establish a complete mechanical theory system, and summarize the motion laws of everything in the world with a strict and unified theory. This is the first theoretical synthesis in the history of human understanding of nature. Mechanics named after Newton is the basis of classical physics and astronomy, and it is also the theoretical basis of modern engineering mechanics and related engineering technology. This achievement has made the mechanistic view of nature represented by Newton occupy a dominant position in the whole field of natural science for 200 years.

Philosophy, religion and others

Aristotle's philosophy emphasizes the harmony of things, and the idea of seeking harmony is correct, but Aristotle thinks that the orbits of the sun, the moon and the stars in the sky are all round, because only the movement of the circle is perfect and harmonious, while the movement on the ground, such as the direct fall of heavy objects, is ordinary. The harmonious thought of ancient Greek philosophers cannot be coherent between heaven and earth. /kloc-in the 7th century, Newton unified the laws of motion of the planets and their satellites in the sky with the phenomenon of gravity falling to the ground, and realized the unity of heaven and earth, which was Newton's great contribution to natural philosophy. As we all know, Newton held the particle theory when he understood the nature of light. But when discussing the nature of light with Hu and Huygens, he said that light has one or another instinct to excite the vibration of the ether. This means that ether is the medium of light vibration (see ether theory). Here, Newton seems to understand the duality of light; Actually, it is not. His view on the existence of ether media is very similar to the ubiquitous air, but it is much thinner, finer and more powerful. He also said that it is the etheric animal temperament that makes muscles contract and stretch, so that animals can exercise. He further explained the reflection and refraction of light, transparency and opacity, and the use of light to produce color. He even imagined that the gravity of the earth was constantly condensed by great temperament. At the end of the explanation in chapter 6 of the second part of Principles, it is said that from memory, he has done experiments and tends to say that ether fills the gaps of all objects, although ether has no perceptible influence on gravity. Since 14 and 15 centuries, European scholars have been fascinated by ether, and the theory of ether has become all the rage. Descartes, the giant of science at that time, was convinced of the existence of ether. He thinks that the motion of planets can be explained by too much vortex. Etherism became a temporary philosophical trend of thought. Newton, who respected experiments, was inevitably involved in this torrent of philosophical thoughts and tended to exist. At that time, people had different views on the function of distance. Newton once pointed out that his law of gravitational interaction is not the final explanation, but only the law summarized from experiments. So Newton did not come to a conclusion about the nature of gravity.

Newton's achievements in science must be traced back to his philosophical thoughts and scientific methods. Newton's student R Coates once revealed the mystery in the preface of the second edition of Principles. Philosophers in ancient Greece and Rome summed up their own conclusions by observing and thinking about natural phenomena (there were similar ones in China's pre-Qin period), such as Thales' theory that the root of all things is water. Even the atomism of democritus and Lucretius is now highly regarded. But their method is called speculative philosophy based on genius's speculation, thinking and debate. In the Middle Ages, scholasticism ruled Europe. Science and philosophy become slaves to theology. In the 15 and 16 centuries, Copernicus, G. Bruno, Galileo, etc. Struggle against the church indefatigably and break free from the shackles of serving God. The atmosphere of observing, measuring and experimenting with natural phenomena has gradually formed. In physics, Galileo's experimental work was the beginning of experimental physics, and Newton was deeply influenced by it. Then Newton made physics as an experimental science to form a glorious system, and at the same time let scientific experimental methods break into the hall of philosophical thought.

Newton thought that scientific principles can be derived from phenomena, or that the basic principles of science can be derived or deduced from phenomena.