Chapter 8 first quarter

On September 4, 1918, after nearly a month of sailing, the "Nanjing" arrived in San Francisco, USA.A month later, Ye Qisun entered the Physics Department of the University of Chicago to study. Why study physics? Confucius said, all things can be established if they are foreseen, and they will be destroyed if they are not forewarned.Ye Qisun, who is full of the idea of ​​saving the country through science, has long used the rational vision of the sages to weave his future studies.As early as January 1915, Ye Qisun revealed his thoughts in his diary: Mr. Xu Zhicheng said that the young people of our country who study in the United States are not like the shipbuilders of Robinson Robinson.When he was in the secondary subjects of Tsinghua University, he didn't take into account the two subjects of literature and reality, whichever was better for him.Once you are promoted to a higher level, you will follow suit, and you will enter a subject, even those who are supposed to be in the literature, turn to practice, and those who are supposed to be in the practice will turn to literature, even if you are at a high level, it doesn't matter. Knowledge is the most suitable for oneself.Time is like a arrow, and in the blink of an eye, four years later, I have graduated from high school and will be sent to the United States. It starts in January to decide on life-long events. If you want it to be correct, yes?What's more, after arriving in the United States, when you apply for a school, if you don't take one subject, you can change another subject.Each husband has the longest ability of one person, but this ability is not easy to discover, it is easy for others to discover it, but it is even more difficult for oneself to discover it.The ancients said that it is more difficult to know yourself than to know others, which is what it means.Therefore, if you want to decide what kind of knowledge you want to specialize in, and think about the purpose of future study, it is extremely difficult. In ancient times, great scholars have spent more than ten years to decide their lifelong behavior. For big things, no matter if you miss it for life, you will be lucky enough to get it, and it is not a firm purpose. If you want to concentrate on learning, you will get it, woohoo!The fees for overseas students, and the indemnity refunded by the United States, have been refunded, and it is not allowed to call it our country's wealth.The motherland spends tens of thousands of dollars to provide overseas students. It is not a sad thing to do so in a perfunctory way for the benefit of the motherland.

What kind of science is the most suitable for one's own physique? What kind of science is my ambition most inclined to? In what science is one's abilities best excelled? The so-called shipbuilding by Robinson in the diary, beside the main text of the diary, Ye Qisun wrote a small note: "After reading this lesson in the morning, I read the section on shipbuilding by Robinson. In the end, even though it is done, there is no way for the pawn to enter the water. It will be futile. Confucius said, everything is forewarned, and I believe it." Ye Qisun underlined the words "everything is forewarned and established", and gave a Chinese understanding of this Western story.We read a few key words from Ye Qisun's diary. He called the major he studied as his "big event in life", and he linked this major event with "seeking the happiness of the motherland". It is not comparable to ordinary people.

Coincidentally, a few years later, Chen Yinke, who was also at Harvard University, also commented on foreign students, which coincided with Ye Qisun's point of view, and it can be said that the heroes have the same views: Philosophy and fine arts in China are far inferior to those in Greece, and not only are science inferior.But the ancient Chinese, who were good at politics and practical ethics, were most similar to the Romans.When he talks about morality, he only pays attention to practicality and does not pay attention to false reasoning. Both his strengths and weaknesses are here.Strengths, that is, the purpose of repairing Qi Zhiping.Weaknesses, that is, the gains and losses of practical things, the observation is too clear, but the lack of profound and far-reaching thinking.Therefore, in the past, scholars practiced stereotyped writing in order to gain fame and wealth; and scholars who studied morality were ultimately a very small number.Nowadays, all overseas students study engineering and industry. They yearn for wealth and honor, and they don't want to study hard.I don't know that industry is based on science.If you don't think about the basics, but treat the end, make the most of it, you will only become a low-level craftsman.If there is a slight change in the theory of the situation, the skills will no longer be useful. The so-called most practical ones will become the least practical.As far as the study of natural principles and human affairs is profound and profound, it has lasted through the ages and has remained unchanged.It can be used anytime and anywhere.In order to save the country and manage the world, it is especially necessary to take the knowledge of the spirit (so-called metaphysics) as the foundation.It is because the overseas students in our country do not know how to study, and despise it, and do not hurt themselves for their ignorance. It is because they emphasize practicality and have not changed their accumulated habits... Husband and country are like individuals. The study of relationships among people must be developed.Therefore, the teachings of Confucius and Mencius in China are learned from the study of human affairs.But Buddhism failed to prevail in China.In particular, those who speak, those who focus on practicality, have no foresight, selfishness, and it is difficult to unite and seek long-term public welfare.That is, on the personnel side, there are also deficiencies.People today mistakenly say that China is too heavy on false principles, and they only seek to import utilitarian and mechanical things instead of seeking spiritual medicine.The history of the Western Kingdom is well-known and can be used as a reference. (Volumes 1917-1924 of "Wu Mi Diary", December 14, 1919)

This is Chen Yinke’s insights after studying in Japan, Germany, France, and Britain since he was 12 years old. At this time, Chen Yinke has re-established his own cultural identity, so he can analyze Chinese culture with a fairly objective and sober academic attitude. pros and cons.He always has a Chinese heart, but his vision is "three eyes".Therefore, the view of the world landscape is so clear and real.There is also a key word in his passage, which is "taking science as the foundation" - "to save the country and manage the world, it is especially necessary to take spiritual knowledge as the foundation".And Wu Mi also had the same opinion. He believed that "most of my colleagues who studied in the United States have low aspirations, but only seek fame and food and clothing; and their academic research is also aimless, and it is mixed with superficiality."It is precisely because they have the same foundation and values, similar insights into that era, and similar heavy life weights, that they became close friends, and they will not change even after half a lifetime of hardships.

The difference is that Chen and Wu chose "spiritual knowledge", while Ye Qisun chose "science as the foundation". In China at that time, these were the wings that made China take off. As Chen Yinke said, among the overseas students, there are many who "seek wealth and honor".Looking through the historical materials, I realized that the craze for studying abroad did not start today.In the history of studying abroad in China, the first overseas student was Yung Wing who graduated from Yale University in the United States.Later, another 120 publicly funded young children went to study in the United States.From 1901 to 1908, 37,850 people went to study in Japan, and 869 people were sent to the United States to study under the "Boxer Indemnity".There are also many people who go to Germany, Britain, France and other European countries to study in other ways.Therefore, this is likely to be the first time in Chinese history to study abroad.

However, in the army of tens of thousands of people studying abroad, as Chen Yinke said, regardless of personal wealth, those who are diligent in learning and working hard on "science as the foundation" are indeed very few. Because of this, Mr. Ren Hongjun, a good friend of Ye Qisun, appealed in the first issue of "Science": "However, if there is no sophisticated and profound learning, it will be learned by the people of the country, and the society will lose its core, and the people will have no beauty. In the past, those who have flourished in the academic forest of China and are entrusted by all living beings are only scientific, and they are only scientific!"

Ye Qisun chose the road of saving the country scientifically, obviously not on a whim, but with long-term mental preparation.We can see from one of his diaries that he has long been aware of the relationship between science and ideals and practicality: ... As a result of the widespread sale of foreign goods, all countries are striving to benefit China. China is the land of the Chinese, and there is no stage for competing with others for profit. , It can also be sad.The only reason is the lack of industry, and the lack of industry is due to the underdevelopment of science. It is also said that although there are many kinds of science, in general, they can be divided into two categories, one is ideal and the other is practical.The distinction between ideal science and practical science has been around for a long time, but until today, scholars have learned more and more, and are discovering novelty every day.The so-called ideals in the past have become realities today. Scholars know that ideals are practical, and there is no limit to them, but they change over time.The two are actually two in one. Ideal is the mother of practicality, and practicality is the achievement of ideals. This is why ideal science and practical science are parallel and complementary...

The reason why Ye Qisun chose physics among other sciences is also the result of his investigation and research. At the beginning of the 20th century, the sun of modern physics first rose in Europe.It was the famous German theoretical physicist Max Planck (1858-1947) who first showed his brilliance. He reported his revolutionary discovery at the German Physics Conference held on December 14, 1900 - the fundamental action quantum h, therefore, this day is unanimously recognized by the history of physics as the beginning of a new era of natural science. h is one of the most important universal constants in nature.To commemorate this major discovery, it was sacredly named "Planck's constant".Immediately afterwards, another dazzling light appeared. In 1905, Einstein was the first to apply quantum expansion to general radiation, and established a new quantum theory of light. He successfully revealed the wave-particle duality of light, just like the hand of God brushed away the clouds covering the sun. Similarly, the spring of physics was born.The third light is the Danish Niels Bohr (1885-1962). In 1913, he generalized quantum theory to any atomic structure and atomic light waves, leading human thinking to wander in the wind and horse of physics and optics. Where the cows don't touch each other, the carols of the harmony of physics and chemistry are sung inside the atom.Subsequently, Louis de Broglie of France discovered that physical particles also have wave-particle duality, and Erwin Schrödinger of Austria also founded wave mechanics based on this.There are also Werner Heisenberg, the German who founded matrix mechanics, and Max Born, a Jew who perfected matrix mechanics, and so on. During the first half of the 20th century, they supported modern physics with different discoveries and the same brilliance. the sun.All of them have won the Nobel Prize in Physics.

Now the sun of physics is shining brightly. Wherever it shines, the material world is no longer the world in its original meaning, but is precisely told that they are composed of molecules, atoms, electrons, neutrons, protons and other microscopic particles. At the beginning of the 20th century, the United States was not yet a center of physics.However, there is a dazzling light shining in the Physics Department of the University of Chicago. This is the 1907 Nobel Prize winner in Physics Michelson (Alberta Braham Michelson, 1852-1931).Michelson was the head of the department at the time.He is known for creating precision optical instruments and a series of extremely precise measurement experiments.Einstein called him an "artist in science" with admiration, and praised him that "the greatest pleasure seems to come from the beauty of the experiment itself and the exquisiteness of the methods used".Michelson took away part of the aura of physics in Europe and let it shine on the once tundra of the United States, which ushered in the spring of physical science for the whole United States.Since him, the second and third recipients of the Nobel Prize in Physics in the United States have completed their own discoveries under his command.From 1892 to 1930, Michelson was the head of the Department of Physics at the University of Chicago, and was once the president of the American Association for the Advancement of Science and the president of the American Academy of Sciences.It is no exaggeration to say that the reason why the United States has caught up with or even surpassed Europe in a short period of time and became the most advanced scientific power in the world is definitely related to the name Michelson.

Of course, it is also inseparable from the sophisticated instruments and laboratories of the Department of Physics.It was in this laboratory with Michelson's soul that Millikan (Robert Andrews Millikan, 1868-1953) completed the famous oil drop experiment and precisely measured the electric quantity of electrons.He won the 1923 Nobel Prize in Physics for this.At the same time, he also carried out precise measurements on the photoelectric effect, which proved Einstein's light quantum theory, so that Einstein won the 1921 Nobel Prize in Physics.The myth of this laboratory continued. In 1923, Compton (Arthur Holly Pton, 1892-1962) came to the Department of Physics of the University of Chicago as a professor.Previously, he was doing x-ray research at Washington University in St. Louis, and found that the scattered x-rays contained a component with a frequency lower than that of the incident x-rays.He named this phenomenon "Compton effect" and explained it with light quantum theory.He later won the 1927 Nobel Prize in Physics.

Ye Qisun clearly noticed what the physics department of the University of Chicago and Michelson himself meant to China.Although the research center of physics at that time was in Europe, he had no choice but to study in the United States.However, students have the freedom to choose their majors.So Ye Qisun chose the most boastful major at the University of Chicago-physics. No one knows exactly Ye Qisun's most secret psychology at this time, but from his life's hard work, from his performance when he once controlled and dominated the power of Chinese students going abroad for further study, from his experience of hardships and humiliation throughout his life Based on this experience, we will come to the conclusion that Ye Qisun's choice is by no means accidental. The hidden motive of this choice is called "saving the country through science". China is like a building that is about to collapse, the country is in critical condition, and there are many disasters. If it is not rescued, it will really be "the country will not be the country".When Ye Qisun set his goal on "saving the country through science", what kind of feelings of blood and tears were there! Since he has the mission of "saving the country", this makes Ye Qisun's choice unusual, even a little "weird".Ye Qisun entered the school in the name of a third-grade transfer student.When choosing a dormitory roommate, Ye Qisun did not choose a student from Tsinghua University, nor did he choose a British or American student, but chose a French student.When asked about the reason, Ye Qisun said that he has basically mastered English, so he can take this opportunity to learn French from his French classmates.Link every detail with learning, this is Ye Qisun. Every summer vacation, he and a few former Tsinghua alumni go to an agricultural university for the summer vacation. Therefore, free accommodation, yogurt, and some fruits and vegetables are provided here. This is really a lot of money, which can be saved for study.Ye Qisun said: "The motherland provides us with huge amounts of money. We should study hard and not waste it. We only hope to return to the country someday." On the contrary, there is another attitude towards life and study. "Business women don't know the hatred of subjugation", and flaunted their grandeur to the United States. Wu Mi recorded in his diary: Rich people such as Hong and Zhu (both acquaintances of Tsinghua University, and their names are not named) have a wealthy family, and their father and brother remitted huge sums of money from China to allow them to spend a lot of money.Hong bought a car, was abducted in the street, and then bought another car (each worth more than 1,500 US dollars, less than 2,000 or 3,000 US dollars, depending on high and low).There is a wealthy businessman (Chinese businessman) whose daughter is quite beautiful, and ants are attracted to her.Hong and Zhu flaunt their wealth to each other for the daughter... Wu Mi severely criticized the strange phenomenon of studying abroad: The situation of Chinese students is extremely short-lived.In a word, most of them seek profit and seek money, receive official fees, and do not study, but serve as deacons in banks, shops, etc.The salary received varies from thickness to thickness.Those who get more money will be envied and respected by all; those who get less money will be despised by everyone.But learning and character are irrelevant, even if you devote yourself to learning and have excellent grades, the public will not know it... And "Ye Qisun is here, strict with his noble personality, fine-tuned his discernment, pick up the good and discard the bad. Choose his strengths and make up for his own weaknesses." He is well-known among overseas students and can be called a model. In addition to continuing to serve as the president of the overseas branch of the Science Society, Ye Qisun often organizes scientific lectures and other activities. In view of the tendency of overseas students to ignore state affairs and only seek personal wealth, he held a "conversation meeting" after discussing with a few friends. .He is not a person who likes to show his face, but this matter is of great importance. Although he is making progress in his studies, how can he realize the dream of saving the country with science alone?Gather sand to form a tower, gather armpits to form fur.If there is a way for everyone to get together, often show people with national events and world situations, and inspire people with new things and new thinking, international students will think of their responsibilities and missions, and they will not be in the colorful world of the United States. Sinking and lost in the gentle countryside.Ye Qisun's idea was approved by everyone, and they decided to hold a talk meeting every Sunday morning, the main content of which was to discuss culture, international trends, and domestic current situation. The conversation initiated by Ye Qisun is described in detail in Wu Mi's diary: November 21, 1920 Sunday.Snow.Initiated by Ye Junqisun, a talk meeting was held, and about a dozen Chinese students from the school gathered. The meeting was held every Sunday morning to discuss knowledge and current affairs in China.It's not a bad intention, but Wei Mi has too many chores at present, even on Sundays, she is still busy.Adding this item is really exhausting, and I know that this kind of meeting, although its name is beautiful, but ordinary Chinese students are ignorant, careless and absurd, how can we benefit from it?However, since Jun Ye brought up this matter, Mi had no choice but to agree to it out of sympathy.At 11 o'clock in the morning on that day, the first meeting was held in the Mi room to study the exclusion of Japanese people in California, and the meeting adjourned after 12:30. Ye Qisun is a more rational person, while Wu Mi is an impulsive and emotional person, but this does not prevent them from becoming close friends.Among Chen, Wu and Ye, Chen Yinke is 4 years older than Wu Mi, and Wu Mi is 4 years older than Ye Qisun.In this way, among the three, Ye Qisun is actually in the position of a little brother.For some reason, Wu Mi respected Chen Yinke like a teacher, and he was courteous to Ye Qisun. Even if he didn't want to attend Ye Qisun's talk, he couldn't say it clearly.Thinking about it, Ye Qisun was too rigorous in his work, but it was really interesting to make Wu Mi, a great scholar, so terrified. In Wu Mi's diary after November 21, Wu Jun briefly mentioned every talk session.However, after all, this is a talk meeting hosted by Ye Qisun. His rigorous, strict and even stern style makes the talk a little "political" and somewhat "official". After more than a month, Wu Mi couldn't bear it. , vented his dissatisfaction in the diary: ... Mr. Ye is here.Ye Jun likes his enthusiasm, he is conscientious in everything, and he is strict with others, but in fact his purpose is not high, and Mi suffers from it. In Wu Mi's eyes, Ye Qisun was weird, he was such a waste of time making conversations, it was like a blind man lighting a lamp, it was useless.However, Ye Qisun never tires of doing it, and the things he is looking for are "restraint and strict, responsible for Qi Yan", and because he is an upright gentleman, he does these things not for himself, but for the country, and he can't say anything about him, so he is loose Wu Mi, who was used to it, had no choice but to yell: Bitter wow... In June 1920, Ye Qisun received a bachelor's degree in physics from the University of Chicago with honors. In September of the same year, Ye Qisun transferred to Harvard University Research Institute in Massachusetts to study for a doctorate in experimental physics, under the tutelage of Percy Williams Bridgman (1882-1961), who later won the Nobel Prize in Physics.An obvious reason why Ye Qisun chose the direction of experimental physics is that the development history of modern physics points out that experiments are an important basis for the development of modern physics, and almost all the masters who won the Nobel Prize in Physics are engaged in experimental physics.At this point, the blinding light of Michelson's lab gave him magical guidance. According to the routine, Ye Qisun at this time can get a doctorate as long as he completes a doctoral dissertation, and many people do the same.But Ye Qisun did not come here for this paper diploma, what he wanted was a complete process, which is the idea, method and steps of scientific research. Half a year later, Ye Qisun chose a scientific research topic that was extremely cutting-edge at that time - "re-determining Planck's constant by X-ray method" to do his first experiment. Planck, a myth in the European physics world, even the great Einstein, facing this mythical character, the emotion he can express most in his heart can only be "what the son wants to say to his father". On October 4, 1947, after Planck finished his life journey, at a memorial service of the National Academy of Sciences, Einstein said with emotion: "I am very honored, and the days with him are unforgettable forever. , very rewarding. He was always after eternal things, while also actively participating in anything human beings do every day... The time I spent in his house, and the many conversations I had with this great man face to face, will last for the rest of my life , will always be the fondest memory, and this will never change, the tragic fate has not separated us from each other." Although Planck and Einstein are two milestone figures in the field of physical science, in the 20th century At the beginning, Einstein's peak was still rising, but Planck's peak had already been built.To choose Planck is to choose the highest peak of physical science. The basic action quantum h discovered by Planck knocked on the door of physics in the 20th century, and all the important contents of modern physics have to be related to it. Therefore, to accurately determine the value of Planck's constant is equal to Quantum h, a mountain of physical science, can measure the precise height, just as we use the latest research results to measure the height of Mount Everest today, which will have important scientific value. The first person to determine the value of Planck's constant was Planck himself.He obtained the experimental formula obtained from the experimental measurement of black body radiation, discovered the basic action quantum h, and derived the black body radiation formula in 1900 based on the experimental data of black body radiation.Einstein also realized the universal significance of the quantum concept, but it was several years after Planck proposed the quantum hypothesis.Einstein was humbly looking for work when Planck published the fundamental action quantum h, and even a year later his father unknowingly wrote to a rather prestigious professor of physics asking He found a job as an assistant for Einstein.He said: "We are not rich, especially my son is more depressed because he can't get a job, so he thinks he is a burden to us... Whether now or next fall, if you can provide him with a position as an assistant , I will be infinitely grateful to you." The physical sky at this time was prepared for Planck.Before him, the British physicist Rayleigh proposed the energy distribution formula of black body radiation based on classical statistical mechanics and electromagnetic theory experiments.The theory is more consistent with the experiment in the long-wave part, but infinite values ​​appear in the short-wave part, while the experimental result tends to zero.This serious deviation is called "ultraviolet disaster" by the academic circles.At this time, the great figure of Planck joined the team of blackbody radiation experiments. He adopted a patchwork method and obtained a formula that both the long-wave and short-wave parts can be consistent with the experiment.He found that as long as it is assumed that the radiant energy of the object does not change continuously, but changes in a certain integer jump, the formula can be reasonably explained.Planck called the smallest indivisible energy unit "quantum" or "energy quantum", and reported this hypothesis to the German Physical Society, thus announcing the birth of quantum. However, the quantum hypothesis is in sharp opposition to the "no jumps in nature" that the physics community has believed in for hundreds of years, and most physicists do not accept this theory.Due to public outrage, even Planck himself was shaken, and even gave up quantum theory, and continued to use energy changes to solve radiation problems. Just when the quantum hypothesis was about to disappear, another great figure joined the research team of quantum theory 16 years later, and he was Einstein.At this time, Einstein, whose situation improved, turned his interest to the quantum hypothesis and successfully saved this great discovery. From the perspective of relativity, Einstein once again cared about quantum theory, probably because he believed that general relativity can deeply understand the microscopic structure of atoms. Six years ago, he had given up on quantum issues and became interested in the Danish scientist Bohr's theory of atomic structure.Bohr believed that electrons only orbit the nucleus in certain specific circular orbits, and do not emit energy when running in these specific orbits, and only emit radiation when it transitions from a higher-energy orbit to a lower-energy orbit energy, which in turn absorbs radiant energy.Bohr solved the stability problem of the atom and successfully explained the spectral law of the hydrogen atom.Einstein thought this was a major discovery. Since the absorption and emission of radiation is due to the jump of electrons from one stationary orbit to another, what pressure God exerted on it between the two, this question will be explored. It is exciting and wonderful.After hovering in Bohr's territory with his intelligent wings for a while, Einstein felt that many problems could not be solved immediately, so he focused his thinking on Planck's quantum hypothesis. At that time, Einstein had already begun to consider agreeing with the quantum theory of gravity.At the same time, Einstein proposed a new connection between Planck's formula and the new atomic theory.Presenting his new paper to Besso, he said: "I have come up with a very good idea about the absorption and emission of radiation. Very simple deduction is obtained from Planck's formula, and everything is done algebraically .” Einstein praised Planck's 1900 derivation as audacious, but the approach Einstein took was universal.Einstein deduced from Bohr's basic postulate that has been widely verified: electrons have many different discrete energy states in atoms, and can change from one state to another through the absorption and emission of radiation.Combined with the assumption of radiation and the heat balance between atoms, we can get Planck's formula.This two-page synopsis also includes stimulated radiation of radiation, so the formulas already imply the theory of lasers that came out 50 years later.What was most important to Einstein was the simplicity of the hypothesis and the generality of the methods that produced it.He thinks this is likely to be the baseline for future theoretical developments. In another article, Einstein pointed out that light rays are not emitted in the form of spherical waves, but needle-like emission with a certain direction, and due to this emitted radiation, the molecules are caused to move a definite distance in the opposite direction.This view is a lot like Einstein's 1905 "heuristic view"—that light is a string of particles. In this essay, Einstein essentially deduced all the properties of the photon: the quantum of radiation, or photon particle.Although Einstein tried to make the term fit the conventions of the time, he was well aware that he was alone in adhering to the quantum assumption of radiation. Six years later, American physicist A. Compton verified the formula proposed by Einstein through experiments, and soon the entire scientific and technological circles were talking about "quantum". With the great influence of Einstein, the eyes of the world are focusing on quantum theory.This shows that a great quantum era is coming. However, such an important constant has no precise value for quite a long time. Although the first value was proposed by Planck himself, it was only estimated by him based on his black body radiation experiment data. .The second person who wanted to challenge this measurement experiment was Millikan, the winner of the 1923 Nobel Prize in Physics, by using the photoelectric effect.Since 1914, he has made precise experimental checks on Einstein's law of photoelectric effect. In 1916, Millikan conducted the famous "oil drop experiment" in the famous laboratory of the University of Chicago. After the value of charge e, h can be determined from the constant h/e, and it can be obtained: h=(6.547±0.008)x10-34js, but this value still has many uncertainties.The third to attack this dangerous peak was dlwebster and fgblack. They announced their experimental results and theoretical basis in 1916 and 1917 respectively. Obviously, the Duane-hunt law they used was more accurate than that of Millikan. The value obtained by using the photoelectric effect should be accurate.At this time, some scholars have followed suit, but none of them can accurately match.It was under such circumstances that Ye Qisun put forward his own idea. He carefully studied the papers of his predecessors and saw the flaws in them.Thus, a bold plan sprouted from his heart. "Xunzi" said: "False horses are not good at feet, but they can travel thousands of miles; The essence of this ancient saying.The reason why science develops is the result of generations of scientists constantly pioneering and innovating on the basis of their predecessors.Millikan said: "The development of a science is like a plant, which grows by adding a very small part step by step. Each research often modifies the previous research, and each new theory is like a great hall composed of many buildings. It is built with a variety of materials." Therefore, Ye Qisun kept in mind his teacher's teachings, and before starting his plan, he carefully studied all the previous experimental measurements of the masters, and found that the experiments of w.duane and fgblack in 1917 had Its merit is that as long as several links are improved, more accurate experimental data can be obtained.Therefore, Ye Qisun invited w.duane to be his instructor, cooperated with hhpalmer, and started their dream-seeking journey in March 1921. Ye Qisun first revisited the determination made in 1917. Under the guidance of w.duane, the preliminary work of this determination is like the tracing and copying of the first stage of Chinese calligraphy practice.The tutor admired this Chinese student who affirmed his own thinking, and he saw the wisdom and humility of young people from ancient oriental countries.In reviewing and "copying", Ye Qisun quickly found out the advantages and disadvantages of previous tests, and boldly put forward his own suggestions for improvement.Ye Qisun first improved the link of voltage measurement, because this value is directly related to the determination of h value.He used the potentiometer principle.In order to improve the accuracy of the potentiometer, he specially designed and wound a high-resistance manganese-copper coil with a total resistance of 6039504 ohms, which can ensure that its resistance value will not change during the whole experiment, thus greatly improving the voltage resolution.This will make the error caused by the voltage measurement negligible, and make the voltage measurement link reach a perfect situation. Another improvement is the precise determination of the shortwave limit.Ye Qisun used the latest X-ray spectrometer, and when the spectrometer was rotated to measure the deflection angle, the spectrometer could hardly observe the eccentricity.However, the testers in the past often failed to meet this requirement. Their spectrometers had eccentricity when they rotated, which caused irregular errors in the readings of the measured x-ray deflection angles. Therefore, the calculated The numbers are not accurate enough. Ye Qisun is an extremely meticulous person. He considered that the x-rays entering the spectrometer are not a parallel beam of x-rays. Therefore, the direction angle of this x-ray needs to be corrected. After taking this correction into account, the measured value obtained is Much more precise. After adopting a series of bold and ingenious improvements, Ye Qisun and his colleagues obtained the data of v and the short-wave limit Bragg reflection angle with high precision, and the relative error was smaller than that of the standard electric wave electromotive force.Using these experimental data and the numerical values ​​of electron quantity (e), (c) and square solution lattice constant (d) used in the world at that time, they obtained h=(6.556±0.009)x10-34js. When the spring of 1921 was about to withdraw from the embrace of Massachusetts, at the Washington meeting of the American Physical Society, Ye Qisun and his collaborators read a stunning work with passionate voices - "Using the Ray Method Re-determination of Planck's constant". The world was in an uproar. The beginning of the 20th century was an era of rapid change, and the sky of science and technology, where physical science played a leading role, was always changing rapidly.However, this is mainly the sky of Western scientists, while the East is still completely intact.In the eyes of most Westerners, Easterners are still asleep and have nothing to do with modern science. Although China is an ancient civilization with four major inventions, she has not yet awakened. However, Ye Qisun taught Western scientists a lesson. A little-known foreign student, a 23-year-old Chinese boy, was able to measure Planck's constant so accurately, which in itself is more sensational than the precise measurement of Planck's constant.How can a person who was wearing long braids and wearing a long gown and mandarin jacket almost yesterday wake up to be able to stand shoulder to shoulder with Western scientists?It must be known that most of the people who determined Planck’s constant are important cities in physics in the world. They are all top scientists. However, the person who announced the more accurate Planck’s constant at the meeting today is a young man from the far east. Chinese people can't help but be amazed that science probably has an innate kinship with the Chinese. The Proceedings of the National Academy of Sciences and the Journal of the Optical Society of America competed to publish Ye Qisun's papers, praising this as "a great progress".The international scientific community quickly stated that Ye Qisun's determination was the most accurate h value at that time. Ye Qisun's name was engraved in the history of natural science in the modern world, and he became the first person in China to win honor for the motherland on the other side of the ocean. Until 1935, ahpton also praised Yip's test in his book as "the most reliable determination of Planck's constant". It is precisely because of the accuracy of this value that no one dared to care about it within 16 years after the 1920s, when the technological level was developing rapidly. In 1922, Ye Qisun extended his tentacles to magnetic research. He studied the influence of hydrostatic pressure on magnetic permeability in the laboratory of high-pressure physicist Pwbridgman (1946 Nobel Prize winner in Physics).In this study, Ye Qisun used the knowledge he had learned, boldly adopted systematic research, and obtained the quantitative relationship between the percentage change of magnetic induction intensity and the pressure and magnetic field intensity.另外，他还认为前人在实验室中考虑不周是没有得出明确结论的又一原因，他认为，要获得正确的结果，必须使样品彻底退磁，前人所述“反常效应”实际上是退磁不完全造成的。叶企孙还对高压磁性进行了理论分析，结论与实验结果相符。这项研究由叶企孙独立进行，是高压磁学的重要进展，因此他的这篇《流体静压对铁、钴、镍磁导率的影响》的博士论文再一次受到了世人的瞩目，成为欧美科学家争相议论的焦点。他的导师pwbridgman教授也在他1931年所著的physics of high pressure中用整整一章的篇幅来介绍叶企孙的“压强对磁导率的影响”，并这样写道：“自从叶企孙的工作之后，rlsteinberger先生用类似装置对一系列铁镍合金作了类似测量。”可见，叶企孙的研究已经影响到了欧美物理学界。 但是，叶企孙最重要的影响还是给了中国留学生以极大的信心。他的成功使中国科学会驻美分社的会员看到了科学救国的曙光。这一年，叶企孙和会员们又重新制定了驻美分社的有关章程，并开展了一系列的学术活动。在叶企孙的影响下，中国留学生在大洋彼岸掀起了一波又一波的科研高潮。 实际上，叶企孙并不是第一个选择物理专业的。在他之前，有留美生李跃邦、颜任光、饶毓泰，在他之后又有吴有训、周培源等等。他们都用自己的优秀证明了自己无愧于那个时代。 吴有训几乎是循着师哥叶企孙的脚印来到芝加哥大学物理系的，从那时起，他们就结下了深厚的友谊，之后虽经半世风雨，却能始终不渝。 1923年底开始，吴有训与自己的导师康普顿着手检验“康普顿效应”。在此之前，“康普顿效应”一直是康普顿教授的心病。在调入芝加哥大学之前，康普顿在圣路易斯华盛顿大学作x射线的散射研究时，发现被散射的x射线中多出一种频率比入射x射线频率低的成分。到了芝大后，他把这一现象定名为“康普顿效应”，并用光量子学说加以解释，认为是x射线光子与电子相碰撞，运用粒子间碰撞遵守能量守恒和动量守恒原理来阐述x射线频率的改变，但他的理论却受到了阻击。 康普顿的实验仅用了碳这一元素进行散射实验，而有人再重复这一实验时，却得不到相同的结果。这个人就是曾为居里夫人助手的杜安尼。这位x射线权威在哈佛大学做了相同的实验，结果却让康普顿沮丧。不仅如此，杜安尼又做了一项新实验，竟发现一种奇怪的现象，因此他提出了“三次辐射”的假设，从而使“康普顿效应”的真实性受到质疑。康普顿本人亲自去杜安尼的实验室察访，也没有看出对方的实验有什么漏洞，只得抽身而退。 显然，“康普顿效应”受到了严重挑战。 就在这时，吴有训加入到支持“康普顿效应”的行列中。他决定对“康普顿效应”进行精密测量。在导师的指导下，他选用7种不同的材料做实验，结果证明了“康普顿效应”的广泛适用性。之后，吴有训又独立完成了一系列精密实验测量，使这项研究更加完整。 1925年11月，美国物理学会第135届会议上，吴有训在大会上被安排在第一个发言，宣读他和导师康普顿的一系列实验结果的论文。他们的论文令全体与会者大开眼界，而盘旋在“康普顿效应”之上的疑云也随之烟消云散。1927年，康普顿因“康普顿效应”的成功而荣获该年度诺贝尔物理学奖。有人还称这一效应为“康普顿、吴有训效应”。 受叶企孙首战告捷为国争光的影响，除了科研方面有吴有训这样的后续捷报外，别的学科领域，中国留学生也不负众望，获得了骄人的业绩。 陈岱孙就得了美国大学生的最高奖——金钥匙奖。 当陈岱孙还是一个哈佛新生的时候，叶企孙早已蜚声于哈佛内外了。 他是清华学校1918年毕业生，我是清华1920年毕业生。但我是1918年秋季才作为一个插班生，考入清华的，而他已于是年夏季毕业赴美留学；所以在清华学习期间，我对他并无识荆的机会。我们的相识开始于1922年，这是他在美国哈佛攻读物理学博士学位最后一年，而是我刚入哈大攻读经济学研究生的第一学年。 虽然专业不同，但当时在哈大的中国学生人数甚少，我们住处又相近，所以时有过从。（陈岱孙《中国科技发展的开拓者，真诚的爱国者（代序）》，见《一代师表叶企孙》，钱伟长主编，上海科学技术出版社1995年版，第2页） 叶企孙是那种慢热和持久型的朋友类型。“我们在星期日也常常聚在一起，讨论一些问题。比方说对国内的情况，他一直很关心。由于出国多年，对国内的情况除了从美国报纸和家信中了解少许外，其他的只有通过来美的留学生、来美人员中了解到。接触时间久了，他那善良的天性才渐渐显现出来。”世界上有两种人，一种人，乍一接触，觉得热情似火，时间一长，友谊反而随着时间的延长而流失；另一种人，则像陈年老酒，时间越长久，酒就越醇香，更能感到他的可敬可亲可爱。叶企孙就是后一种人。 叶企孙对待学问很有中国古代士子的风骨，谦虚谨慎、不骄不躁，不虚美、不隐恶，既有持之以恒之毅力，又有壮士断腕之果敢，和他相处，点滴交融耳濡目染，使陈岱孙获益颇大。陈岱孙以叶企孙所取得的学术成就为荣，叶企孙也热情鼓励这个学业上刻苦努力的小兄弟。陈岱孙确也有绝不服输的性格，“那时，我是个小伙子，班上有五十多岁出过著作的学者，他们不把我们当回事，我要和他们比试比试”。整整4年，陈岱孙从不外出游玩，在图书馆中专用的小房间发奋读书。“竞争十分激烈，我是连滚带爬地读完了书。”终于到毕业之际，陈岱孙因学习成绩杰出，荣获了美国大学生的最高奖——金钥匙奖。1927年，当陈岱孙从国外返回清华任教时，叶企孙已经在清华多时了。 由于时局关系，我自沪北上交通受阻，到校时晚。住处未定，他让我搬进他所租赁的校内教职员住宅区宿舍，和他同住。是后，除我们分别休假离校的两年外，我们在这宿舍中一直同住了五年。又是后，除了他于1941年-1943年期间在重庆任中央研究院总干事，和我于1952年-1953年期间在北京中央经济学院任职外，我们一直是清华、西南联合大学、北京大学的同事。时间久了我们间有着深厚的友谊。我对于他的方正品德、学术造诣、学者风度，深为钦仰。（陈岱孙《中国科技发展的开拓者，真诚的爱国者（代序）》，见《一代师表叶企孙》，第2页） 患难之中见真情。这对“有半个世纪以上的友谊”的老朋友，在晚年的时候还在谱写着可歌可泣的友谊之歌。叶企孙蒙冤入狱，出狱后病体羸弱，当时“文革”正盛，人人自危。陈岱孙却不畏人言，顶着政治压力，多次去叶企孙住所看望，馈赠礼品，谈笑如初。这一切都给正值霜雪之中的叶企孙以莫大的安慰。1994年，“叶企孙奖”基金设立并《一代师表叶企孙》出版之际，陈老欣然题词：“哲人往矣，风范长存”，以此遥寄自己对老友的一腔深切怀念。 继叶企孙、吴有训、陈岱孙等第一代留学生为祖国争得荣誉之后，又有更多的第二代、第三代甚至第四代学生相继在大洋彼岸获得了成功，他们是王淦昌、施士元、王竹溪、赵九章、彭桓武、邓稼先、钱三强、钱学森、李政道、杨振宁、吴健雄等等，但若溯本寻源，追索谁是第一个在近现代科学界为中华民族赢得荣誉的人，非叶企孙先生莫属。 值得回味的是之后的那些人大都是叶企孙的学生，或者是他学生的学生。而叶企孙们更大的贡献则是为中华民族立于世界之林争取了时间和为祖国完成了科学技术人才上的准备。 这也是叶企孙的一生可以用“伟大”两个字概括的原因。