The contribution of physics to the progress of society, and the inspiration derived therefrom

The Development of Physics and the Progress of Human Science The world has passed from obscurity to clarity, and the light of scientific care has scarcely ceased to shine for an instant, and all the vague and impossible scenes and all the extraordinary imaginings are likely to be made submissive, orderly, ethereal, and stable by the gentle touch of science. The wind sends a breath of precision and delight, and the fruit of an encounter with intelligence and inspiration may well come to earth in the twinkling of an eye in the form of a texture. It stands in reality, marking the triumph of today over yesterday; or signaling that people's yesterday's way of life is gone; or marking that a great man of science has come slowly to earth ...... In the dawn of mankind, or in those days of the past as far as our knowledge can know them, we can indeed see that science, in the broad and long region of It has experienced difficulties and failures, but it has also driven history forward with a force that has changed everything, and has built a monument of glory as far as the eye can see. Faith, passion, fervent hope and infinite joy is any one of these monuments suggests to us the direction of life, so that we believe in diligence, hard work, love of life, deep thinking and high lifting ...... At the same time, we also more see the deep charm of the science itself, humanities or nature, scientists or a specific thing, are like a vertical sky to see. The science of science itself is y fascinating, humanistic or natural, scientists or a specific thing, like a mirror that can be seen in the sky stands in front of us, we have to move forward and upward because it is inevitable to stand in front of it to sort out their own rationality and emotions, and in its reflection of the brilliant light to draw wisdom and strength, so that our creativity is more supportive, and more because of the accumulation of the abundance of the more powerful and reliable.

At every stage of human development, physics has always stood at the forefront of the emancipation of productive forces, and every small progress in the development of physics is accompanied by great difficulties and twists and turns, and it is only in the long term collision between tradition and reality that it can be developed and progressed, which is not only glittering with the aura of the wisdom of pioneers, but also with countless scientific pioneers in the pursuit of scientific truth. There is also the blood and tears of countless scientific pioneers in the quest for scientific truth on the road of unyielding struggle. As the youth of the new era, it is very necessary to tread this thorny road, we do not expect that every time on this road can pick up the flowers, even if every time as long as you can smell the refreshing fragrance of flowers on this road, it is also considered to be the countless pioneers of science to the soul of the British consolation. This is the original intention of this series of lectures on popularization of science. (I) The Enlightenment and Development Stage of Physics The development of physics has experienced a very long enlightenment stage. Until the Middle Ages, physics was not recognized as an independent science, and for a long time it was classified under the category of philosophy. In this long period of time, people are according to the needs of the productive forces at that time or the will of the ruler to develop and utilize the knowledge of physics (from unconscious to subconscious), is to I according to the human development process of the level of development of the productive forces as well as the degree of application of the knowledge of physics, this period of the enlightenment stage of physics for the following divisions:

1, the age of firearms:

The human ancestors first carried out the division of labor between hands and feet, and used their free hands to make tools, which improved the efficiency of labor. The earliest tools made by human beings in this period were stone tools, and the manufacture of stone tools announced the beginning of labor, as well as the enlightenment of simple physics.

With the development of stone tools, the emergence of a more complex tool - the bow and arrow, which gave rise to the "hunting" of the earliest production sector. Human ancestors with their own wisdom and experience made stone axes, stone knives, bows and arrows, where we can use the principles of physics to illustrate its superiority: pressure and pressure is proportional to the area of the force is inversely proportional to the pressure. Stone axe stone knife blade is made very thin in order to reduce the force area to increase the pressure, so that they are not under great pressure can enter the object; the use of the bow and arrow not only use the knowledge of physics in the pressure, but also use Newton's third law - when the arrow to the bowstring a force, the bowstring at the same time also give the arrow a reaction force so that the arrow can be shot. The fact that this subtle idea was tapped into by our ancestors is a testament to the progress of our ancestors' thinking.　

As we know, the idea of "drilling for fire" is of great significance in the history of human development. It is no exaggeration to say that this is the first great revolution in the history of human science and technology. With the realization of artificial fire, marking the human race has been "in practice invented mechanical movement can be converted into heat", "for the first time so that human beings dominate a natural force, and thus ultimately separate people from animals.

With the technology that can make fire at any time, it is possible to make fire into all areas of human production and life. In production, people first invented the use of fire to make pottery - the emergence of pottery technology, marking the first time that human processing of materials to change the nature of the material, thus creating an artificial material, and in the process of processing the first use of natural energy. Later mankind learned the techniques of copper and iron smelting. The world's earliest pig iron smelting technology, appeared in China in the Spring and Autumn period, to the Warring States period, iron has been widely used. By the time of the Eastern Han Dynasty, there were large iron smelting blast furnaces with a height of five or six meters and a volume of thirty or forty cubic meters. On the basis of iron, China also invented the earliest steelmaking technology, and the steelmaking process at the same time also developed the quenching technology. In this way, about the end of the Han Dynasty, China's ancient iron smelting, casting and forging, steelmaking and quenching technology has formed a relatively complete system, a variety of processes and methods have been roughly complete, at that time the world in the absolute leading position. Thus laying the foundation for the processing technology of the most basic materials throughout the feudal era.

Under the technical conditions of fire and fire, mankind has realized the transition from stone tools to copper and iron age in human history has caused a revolution in the production tools, greatly promoting the development of agriculture and handicrafts, so that the productivity has made unprecedented progress. And iron civilization is not only the development of technology, but also promote the birth of science. 2, leading the world of Chinese physics in the Middle Ages

In China's thousands of years of feudal society, in the history of war and chaos in the gap, China's science and technology has not slowed down the pace of progress, China's ancient scientific and technological system has gradually been improved and enriched. And emerged such as Wang Chong, Zhang Heng, Liu Zheng, Zu Chongzhi, Jia Si Fo, Bi Sheng, Shen Kuo and other famous scientists. Among them, Zhang Heng had made the world's earliest use of water rotation of the Hunxiang, that is, Hun Tianyi, and an instrument that can determine the direction of the epicenter of the earthquake, named "Waiting Wind Earthquake Instrument", which is the world's first seismograph, its sensitivity is very high, more than 1,700 years than Europe's geodesic instrument; in the field of weights and measures, no matter whether it was invented in China in the ancient times in the astronomical In the field of weights and measures, whether it is China's invention in the ancient times in astronomy through the establishment of the kuai table shadow measurement for the observation and award of time, or later people in practice invented the use of hydrostatic pressure to measure the time of the instrument - leakage carving, in the ancient times without clocks and watches is a very remarkable invention, in the long-distance measurement of the length of the time was invented to measure the mileage of the drum car, and when the time came to measure the mileage, the drum car was invented. Measuring the mileage of the drum car, when the car is moving forward, the use of the rotation of the wheels, can be directly or indirectly the distance traveled by the car expressed, which at that time the world can be said to be the first; to the Song and Yuan dynasties, due to the development of production, economic prosperity, the implementation of the policy of supporting science and technology and scientific and technological exchanges between ethnic groups, between Chinese and foreign science and technology, the Song and Yuan dynasties science and technology in the Sui and Tang dynasty, reached the peak of scientific and technological development in ancient times. The science and technology of the Song and Yuan dynasties reached the peak of the development of ancient science and technology. During this period, metallurgical technology, famous kilns and porcelain, construction technology, textile technology, water conservancy construction, shipbuilding and navigation technology had great development, especially worth mentioning as one of the four great inventions of ancient China, the compass has been widely used in navigation in continuous improvement, as one of the four great inventions of gunpowder in the improvement of the technology of firearms and weaponry to great extent, as recorded in the history book of the "Flying air to hit the thief Zhentian Lei Cannon" and "divine fire flying crows", still as the prototype of modern rockets and rocket artillery, as one of the four great inventions of the collodion lithography on the development and progress of world civilization has played a huge role in promoting ......

In short, the achievements of Chinese science and technology in the Middle Ages are gratifying, but with the development of time, Chinese science and technology entered a period of slow development in later years, while European science and technology is rising rapidly and quickly after the "Dark Ages" of science. Rise by leaps and bounds, and quickly overtook China. 3. The later rise of brilliant Western physics

It is worth mentioning here the Western civilization in this period. Before the feudal society, the ancient Greek science and culture in Europe in a leading position: the most famous scholars at that time is later called "the father of science" Thales, Western historians, he put forward the principle of the relationship between the shadow and the length of the physical object is proportional to the principle, and the use of this principle to accurately measure and calculate the height of the pyramids of Egypt; the same time period There also appeared another for later generations praised the scholars of ancient Greece - Pythagoras, he put forward the doctrine that mathematics is the basis of everything in the universe, and to put forward the Pythagorean theorem (i.e., the hook string theorem) and famous, he also discovered the irrational numbers, giving rise to the first "Mathematical Crisis"; there was also a very influential scientific authority at the time, Lioukibe, who, together with his successor Democritus, put forward the theory of atomism, which, it should be known, is the cornerstone of modern science; among the ancient Greek scholars, the most influential figure for the In the ancient Greek scholars, the most influential figure is Aristotle, who set the Athenian school of the great success of astronomy, physics, biology, medicine and other aspects of in-depth research, in the development of natural sciences at that time to make a great contribution; ancient Greek scholars, there is also a famous scientist --- Archimedes, he discovered the theory of atomism, and his successor Democritus put forward the atomic theory. Archimedes, he discovered the law of buoyancy, the principle of leverage, etc., and the use of the principle of leverage, clever invention of pulleys, screws, named after Archimedes Archimedes screw, in the modern machinery is extremely wide range of applications, he is a very important experimental inventor, has created a lot of instruments and machinery, especially in the military invention of a lot of, in addition to his astronomy, geometry, mathematics, pi, and so on, all have In addition, he made special contributions to astronomy, geometry, mathematics, pi, and so on. Therefore, the history of science says that Archimedes "stood at the highest peak of the whole Greek and Roman ancient scientists and added glory to the Alexandrian period", "was the theoretical genius and practical genius in one theoretical incarnation, and matched the great figures of recent times, and in many fields there were great original and real discoveries" ......

In the Middle Ages, Europe developed rapidly and effectively in astrophysics. Among the leading figures were Copernicus, Bruno, Ditgu, and K?bler. The greatness of Copernicus was the realization of the combination of the sun-centered theory and the mathematical methods that existed in the past, so that the sun-centered theory was firmly established on the basis of actual observations and scientific calculations, so that science entered a new era. In his Theory of the Operation of the Heavenly Bodies, published in 1543, he pointed out that: (1) the earth is not the center of the universe, but only the center of the gravitational lunar orbit; (2) all celestial bodies orbit around the sun, so that the sun is at the center of the universe; (3) the distance from the earth to the sun is much less than the distance from the earth to the stars, so that stars appear to be motionless; (4) the earth, like other planets, orbits around the sun, and the sun's apparent motion arises from the motion of the Earth; (5) the planet's apparent inverse motion is not caused by its own motion, but comes from the motion of the Earth. Copernicus also largely depicted the true picture of the structure of the solar system --- people see the sun, moon and stars rise in the east and fall in the west, is the result of the Earth's own rotation; Mars, Jupiter and other planets in the sky sometimes prograde, sometimes retrograde, is not what the Emperor's Church said " action strange, secretive movements", but due to its orbit around the sun and the speed of the orbit caused by the different integrated performance. Copernicus, as a Catholic, was well aware of the "danger" of his doctrine, so he delayed publishing it. It was only at the urging of his friends that he published a copy of the manuscript of the Theory of the Operation of the Heavens in the year of his death (1543).

The Italian astronomer Bruno was an active propagandist and defender of Copernicus's doctrine, and in 1584 he published On Infinity, the Universe, and the World, which developed Copernicus's doctrine and became a famous astronomer. Unfortunately, due to his strong opposition to geocentricity, embraced Copernicus's heliocentricity, advocating that the universe is infinite, was branded as a heretic by the Church, and was burned alive on March 17, 1600 in the Piazza della Florentina in Rome.

After 1600, K?bler became the assistant of Dagu, and began to cooperate with Dagu, which is a wonderful example of scientific cooperation in the history of science. 1601, when Dagu died, he left all the extremely valuable astronomical data he had collected during his life to K?bler, who, after careful summary and study, published his work in 1609, announcing two laws about planetary motion ---The "Law of Orbits" and the "Law of Areas", and after nine years of study and countless calculations, he discovered the third law ---The "Law of Periods" (I will not go into the details of the three laws here). The great contribution of Kepler's three laws of the planets is to advance Copernicus's theory one step forward, providing professional astronomers and mathematicians with a strong argument in favor of heliocentricity, and being called "astronomical legislator" by later generations.

Here to say another scientist Galileo we may be more familiar with (the isochronous principle of the pendulum and the famous Leaning Tower of Pisa falling experiment), he is in the history of modern science, is an epoch-making representative of the figure, he has made significant contributions to astronomy, mechanics, physics, mathematics, and so on, recognized as the founder of the modern experimental science, and for the establishment of the later classical physics, indelible contribution, is the most important of the contemporary science and technology, and is the most important of all. Indelible contribution to the establishment of classical physics, is worthy of the "father of modern physics". (ii) The first golden stage of the development of physics --- the establishment of classical mechanics

Galileo's emergence opened up the precedent of experimental physics, and provided a lot of arguments for the establishment of classical physics, but many of his discoveries were the denials of Aristotle's doctrine, and therefore were also criticized by the Roman Papacy. denial, and was therefore also warned by the Holy See. His publication in 1632 of the Dialogue Concerning the Two World Systems of Ptolemy and Copernicus further enraged the Church and even the Pope himself, and in 1633 Galileo was summoned by the Inquisition and sentenced to life imprisonment. During his imprisonment he overcame many obstacles and wrote his scientific masterpiece, Dialogue Concerning Two New Sciences. Galileo managed to send this work secretly to the Netherlands, where it was published in 1638, making a great contribution to the development of modern science. His summary of a series of basic concepts and fundamental laws in the new dialogue about the knowledge of mechanics became the basis of the three major declarations of mechanics put forward by Newton later, and not only that, he also created the modern scientific research method combining experiment and mathematics. So it is not too much to say that he is the founder of modern physics, is the fighter of science, is to open the door of modern science, is not too much.

In 1642, Galileo died, but another future of science was born, he is the future British physicist, mathematician, astronomer, founder of classical physics Newton.

In 1661, at the age of 18, Newton entered Cambridge University and had the opportunity to learn Euclid's Principia Geometria. He later wrote his brilliant work, The Mathematical Principles of Natural Philosophy, in accordance with Euclid's Geometrical Principles.In 1664, Newton became an assistant to his teacher, Barrow, and had to return to his home town in 1665 when the plague struck London. On the surface, Newton seemed to be living in the middle of a poor countryside, but in his mind there was a huge wave of scientific revolution. In his hometown for a year and a half, Newton's life in the full play of creativity in the period, but also the modern history of science, mathematics, optics, mechanics of the "golden age". He invented calculus, put forward the famous "gravity", he also through the prism to decompose light into seven colors of monochromatic light, thus laying the theoretical foundation of modern optics.

In 1666, Newton made a reflecting telescope capable of magnifying more than 40 times, and in 1671, he formally submitted a paper on the reflecting telescope to the Royal Society; the next year, he submitted "A New Theory of Light and Color" to the Royal Society. These optical treatises were the first scientific achievements in which Newton demonstrated his scientific talents and made them known to the world. Newton in physics, in addition to the mechanics, thermodynamics, optics and other aspects of the achievements, more importantly, he is also the founder of classical physics. On the basis of the work of Galileo and others, he carried out an in-depth study, summarized the three laws, and created the system of classical mechanics:

Newton's first law:

Any object forced to change its state by an external force, before it will remain at rest or in uniform linear motion.

(This is the original expression of the law of inertia that we are studying today)

Newton's second law:

The change in momentum is proportional to the force applied, and is in the direction of that force's action

(This is the original expression of Newton's second law, "Forces are responsible for the acceleration of objects," which we will study in our first year of high school. "

Newton's Third Law:

Acting forces and reaction forces are equal in magnitude and opposite in direction. In other words, the interaction force between two objects is equal in magnitude and opposite in direction.

(The law we have learned so far in middle school, just not in the form of a law)

Newton's three laws about the motion of an object are the basis for our understanding of all mechanical phenomena, and are the basis for the whole of classical mechanics.

The story of Newton's discovery of the law of gravity, the "apple falling to the ground", is widely rumored, but in fact it is just a story. Even if this did happen, we should not overstate the significance of the event itself, but we have to be inspired by this story, to pay attention to observe every phenomenon that occurs around us. To say that Newton discovered the law of gravity because he saw an apple fall to the ground would be an oversimplification of history (though the fact that this story has been circulating in the West and that there is a common saying that "God said, "Let Newton do it" is a testament to Newton's prestige in the scientific community at the time). On a historical level, among the giants of science who contributed to the discovery of the law of gravity, Kobler and Galileo are the first to be recognized. Newton was merely the mastermind and solved the problem that others failed to solve, taking the final, supreme step. Hegel, the famous German philosopher, has said, "K?bler, who was starved to death by the Germans, was the true founder of modern celestial mechanics; and Newton's law of gravitation is already contained in all three of K?bler's laws, and is even manifestly expressed in the third law." It is no wonder that he spoke of his achievements in the natural sciences in such modest terms as "like a child playing on the beach who is delighted to find a few shells", and "all my achievements are due to the fact that I have stood on the shoulders of giants". In short, the birth of the law of gravity, the then celestial mechanics and even the contemporary study of celestial mechanics, provide the most important theoretical guarantee.

In the process of the creation and continuous improvement of classical mechanics, people began to realize the importance of the scientific method, especially the importance of the experimental method. The first in history to explore the new method is the famous British philosopher Bacon, who advocated in the book "New Tools" to unify the functions of experience and rationality, to obtain scientific knowledge, first of all, experiments should be conducted, and finally in practice to reach a conclusion, another proposed experimental scientists is Galileo, who believes that the real science is the universe, the natural world, and that people must be experimented with to read this "book of nature". It can be said that it was Bacon and Galileo stood on the practical and theoretical work to show the direction of science, so that the natural sciences from philosophy and become an independent discipline. It is important to realize that the art of eloquence - elegant language and argumentative skills - is of no use in the field of natural science, which must speak through experimental facts. And the facts speak for themselves: later Torricelli, Pascal, Boyle, Newton, Thomas . Young, Meyman and other scientists of the research results, are based on the experimental basis.

By the 18th century, Newtonian mechanics marched toward both depth and breadth. On the one hand, through human efforts, modern mathematical methods are widely used in mechanics, the formation of "analytical mechanics", it is even regarded as a new branch of mathematics; on the other hand, Newtonian mechanics and the combination of specific physical properties, the formation of the "mechanics of solids", On the other hand, Newtonian mechanics, combined with specific physical properties, formed the "solid mechanics", "elastic mechanics", "fluid mechanics" and many other branches of mechanics, so that mechanics has reached a fairly perfect point.

It can be said that in the era of Galileo and Newton, mechanics has formed a rigorous, complete, systematic scientific system, becoming the first "golden age" in the history of the development of physics. It is because of the mechanics of the drive, the physical discipline has taken shape, and in another group of scientists under the efforts of the deeper and wider into the field.

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