Einstein/Kloc-graduated from Zurich University of Technology in 0/900, and began to teach in this university in 0/909. 19 14 was the director of the Royal William Institute of Physics and a professor at the University of Berlin. He was forced to immigrate to the United States and became an American citizen on 1940.
/kloc-the late 0/9th century is a period of change in physics. Einstein re-examined the basic concepts of physics from the experimental facts and made a fundamental breakthrough in theory. Some of his achievements greatly promoted the development of astronomy. His quantum theory has a great influence on astrophysics, especially theoretical astrophysics. The first mature aspect of theoretical astrophysics-stellar atmosphere theory is based on quantum theory and radiation theory. Einstein's special theory of relativity successfully revealed the relationship between energy and mass and solved the long-standing problem of stellar energy. In recent years, more and more high-energy physical phenomena have been discovered, and special relativity has become the basic theoretical tool to explain this phenomenon. His general theory of relativity also solved a mystery in astronomy for many years, and deduced the phenomenon of light bending that was later verified, which became the theoretical basis of many astronomical concepts later.
Einstein's greatest contribution to astronomy is his cosmology. He founded relativistic cosmology, established a static finite and infinite self-consistent dynamic universe model, and introduced new concepts such as cosmology principle and curved space, which greatly promoted the development of modern astronomy.
Brief introduction to life
1879 was born in Ulm, Germany, a small owner's family who runs an electrical appliance workshop. A year later, my family and I moved to Munich. 1894, his family moved to Milan, Italy. From 65438 to 0895, he transferred to the state middle school in Arau, Switzerland. 1896 entered the normal department of Zurich University of Technology to study physics, 1900 graduated. 190 1 acquired Swiss nationality. 1902 After graduating from university, I was unable to enter academic institutions. He just found a temporary job as an examiner in Bern, Switzerland, and was hired as a technician in Bern, Switzerland, engaged in technical appraisal of invention patent applications. But there, Einstein's scientific passion stifled by formal education finally reappeared in Generation, and his relaxed work allowed Einstein to continue to devote himself to scientific research.
He used his spare time to do scientific research. 1905, Einstein, who was nearly 26 years old, published three papers in succession (light quantum, Brownian motion and special relativity), and made historic achievements in three different fields of physics, especially the establishment of special relativity and the proposal of light quantum theory, which promoted the revolution of physics theory. In the same year, he received his Ph.D. degree from the University of Zurich with his thesis "A New Method for Determining Molecular Size".
Einstein was a part-time lecturer at Berne University from 65438 to 0908. 1909 left the patent office and became an associate professor of theoretical physics at the University of Zurich. 191/kloc-0 was a professor of theoretical physics at the Deutschland University in Prague, and 19 12 was a professor at his alma mater, Swiss Federal Institute of Technology in Zurich. 19 14 years, at the invitation of Max Planck and Walter Nernst, he returned to Germany as the director of the Royal Institute of Physics William and a professor at the University of Berlin until 1933. 1920 At the invitation of Hendrick Antoine Lorenz and paul ehrenfest, he was also distinguished professor of Leiden University in the Netherlands. After the outbreak of World War I, he devoted himself to public and underground anti-war activities.
Einstein published his general theory of relativity in 19 15. His prediction that light will bend after passing through the gravitational field of the sun was confirmed by the observation of the total solar eclipse by British astronomer arthur stanley eddington in 19 19. 19 16 The gravitational wave he predicted was also confirmed in 1978. Einstein and relativity have become household names in the west, but they have also attracted vicious attacks from chauvinists, militarists and anti-Semitists in Germany and other countries.
19 17, Einstein put forward the theory of stimulated radiation, which became the theoretical basis of laser.
Einstein was awarded the 192 1 Nobel Prize in Physics for his research on photoelectric effect. 1933 1 10 After the Nazi Party seized the German regime in October, Einstein was the primary object of persecution in the scientific community. Fortunately, he was giving a lecture in America at that time and was not killed. Returning to Europe in March, he took refuge in Belgium. On September 9, he found himself being followed by the Gestapo who planned to assassinate him. He crossed the ocean in the starry night, transferred to Princeton University in the United States in June 5438+10, and served as a professor in the newly-built Institute for Advanced Studies until his retirement in June 5438 +0945. 1940 Obtaining American citizenship.
1939, he was told that uranium nuclear fission and its chain reaction were discovered. Under the impetus of Hungarian physicist Leo Szilard, he wrote to President Roosevelt and suggested developing an atomic bomb to prevent the Germans from taking the lead. On the eve of the end of World War II, the United States dropped atomic bombs over Hiroshima and Nagasaki, Japan. Einstein was strongly dissatisfied with this. After the war, the United States waged unremitting struggles and launched a peaceful movement against the dangers of nuclear war and fascism.
Einstein died of ruptured aortic aneurysm at Princeton. According to his will, there will be no funeral, no grave, no monument, and the ashes will be scattered in a place that will always be kept secret, and no place will be sacred. Einstein spent the rest of his life exploring the theory of grand unification, but this work has never been successful. Now the grand unified theory is the central issue of theoretical physics research.
1955 In April, Einstein signed the Russell-Einstein Declaration on his deathbed, calling on people to unite and prevent the outbreak of a new world war. Einstein was not only a great scientist but also a pacifist. He witnessed the destruction of human civilization in two world wars and thought that peace was the primary problem of mankind.
1999 Time Magazine selected him as the man of the century.
The objective existence of atoms and molecules made the German chemist ostwald, who was the most firmly opposed to atomism, take the initiative to declare that "the atomic hypothesis has become a scientific theory with a solid foundation" in 1908.
1In June, 905, Einstein finished his long paper "On Electrodynamics of Moving Objects", which initiated a new era of physics and put forward the special theory of relativity completely. This is the result of Einstein's ten-year exploration, which largely solved the crisis of classical physics at the end of 19, changed the space-time view of Newtonian mechanics, exposed the equivalence of matter and energy, and created a brand-new world of physics, which is the greatest revolution in the field of modern physics.
1905 In September, Einstein wrote a short article, is the inertia of an object related to the energy it contains? ",as an inference of relativity. Mass-energy equivalence is the theoretical basis of nuclear physics and particle physics, and it also paved the way for the release and utilization of nuclear energy in the 1940s.
In this short period of six months, Einstein's breakthrough achievements in science can be said to be "unprecedented". Even if he gave up physics research, even if he only accomplished any of the above three achievements, Einstein would leave an extremely important mark on the history of physics development. Einstein dispelled the "dark clouds in the clear sky of physics" and ushered in a more brilliant new era of physics.
Growth resume
1March 879 14 in the morning 1 1: 30, Einstein was born at 135, Ulmbanhof Street, Germany. Both parents are Jewish. My father's name is Herman Einstein and my mother is Pauline Kirk.
1884, Einstein was fascinated by the pocket compass when he was five years old.
From 65438 to 0885, Einstein began to learn the violin.
1886, Einstein studied in the parliamentary school in Munich. Studying Jewish canon at home.
From 65438 to 0888, Einstein entered Louis Polder High School. Continue to receive religious education at school and accept the rite of passage. Friedman is the instructor.
From 65438 to 0889, he read popular science books and philosophical works under the guidance of medical college student Talme.
189 1 year, I taught myself Euclidean geometry, and I was crazy about it. At the same time, I began to teach myself advanced mathematics.
1892, I started reading Emanuel Kantor's works.
1895, taught himself calculus.
1896, graduated from Arau Middle School. In June, 5438+00, he entered Zurich Normal University of Swiss Federal Institute of Technology to study physics.
189910 June 19, Einstein formally applied for Swiss citizenship.
1900 In August, Einstein graduated from the Federal Institute of Technology in Zurich, Switzerland; In February, 65438, the paper "Inference of Capillary Phenomenon" was completed and published in Leipzig Journal of Physics the following year.
190 1 year, and obtained Swiss nationality on March 2 1 day. From May to July this year, I finished my thesis on the thermodynamic theory of potential difference.
1904, in September, the trainee of the patent office became a formal third-class technician.
1905 In March, the quantum theory was developed, the light quantum hypothesis was put forward, and the photoelectric effect problem was solved. In April, he submitted his paper "A New Method for Determining Molecular Size" to the University of Zurich, and received his doctorate. In May, he finished the paper "On Electrodynamics of Moving Objects", and put forward the principle of special relativity independently and completely, which initiated a new era of physics.
1906 was promoted to the second-class technician of the patent office in April. 165438+ 10, the paper on specific heat of solids was completed, which is the first paper on solid quantum theory.
1908 10 is a part-time lecturer at the University of Bern.
1909 10 left the Berne patent office and became an associate professor of theoretical physics at the University of Zurich.
Finish the paper on critical opalescence.
19 12 put forward the photochemical equivalence law.
19 13 12 7 accepted the title of academician in Berlin.
1965438+April 6, 2004, moved from Zurich to Berlin.
19 15, 1 1 June, 2008, put forward the complete form of the gravitational equation of general relativity, and successfully explained the motion of mercury at perihelion.
1965438+In March, 2006, I finished the summary paper "The Basis of General Relativity". In May, the hypothesis that the universe is finite and unbounded was put forward. In August, he completed the quantum theory of radiation, summarized the development of quantum theory and put forward the theory of stimulated radiation.
19 19 Einstein's theory is considered as "one of the greatest achievements in the history of human thought". In February, 65438, he received the only honorary degree in Germany: the doctorate of medicine from the University of Rostock.
1921From April 2 to May 30, Weizmann and I visited the United States for the first time in order to raise funds for the establishment of the Hebrew University of Jerusalem in Jerusalem.
1922 1 completed the first paper of unified field theory. In July, he was threatened with murder and temporarily left Berlin. On October 8th, 65438/KLOC-0, Einstein and Elsa went to Japan by boat in Marseille. Visit Colombo, Singapore, Hong Kong and Shanghai along the way. 165438+1On October 9th, Einstein was awarded the Nobel Prize in Physics 192 1 year. 165438+1October17-65438+February 29th, I have been to Japan.
1923 In July, he went to Gothenburg to receive the Nobel Prize of 192 1. In February 65438, it was first speculated that the quantum effect might come from the overconstrained field equation of general relativity.
Bose-Einstein condensation was discovered in 1924.
1926 was elected as an academician of the Soviet Academy of Sciences.
1928 was 1 year, and he was elected as the director of the German Human Rights League (formerly known as the German New Motherland League).
1929 March, 50th birthday, hiding in the suburbs to avoid birthday celebrations. On June 28th, he won the Planck Medal.
1930 is the year of 65438+ February11~1931. On March 4th, Einstein visited the United States for the second time and gave a speech at California Institute of Technology.
1932 Corresponded with Freud in July to discuss the psychological problems of war; Call on the German people to stand up and defend the Weimar Republic and oppose fascism with all their strength.
193365438+1October 30th, the Nazis came to power. On March 10, I made a statement in Pasadena that I would not return to Germany and set off for Europe the next day. On March 20th, the Nazis searched his house, and he protested. After that, his property in Germany was confiscated and his works were burned.
1935 In May, he formally applied for permanent residency in the United States in Bermuda. That year, in order to get the Nobel Prize (Peace Prize) awarded to Ausier Tsky, who was imprisoned in a Nazi concentration camp, he ran around.
/kloc-0 supported China's "Seven Gentlemen" in March, 937.
1September, 938, he wrote a letter to future generations after 5,000 years, expressing his dissatisfaction with the present situation of capitalist society.
1On August 2, 939, he wrote to President Roosevelt, suggesting that the United States should pay close attention to atomic energy research and prevent Germany from mastering the atomic bomb first.
1940 telephoned Roosevelt on May 22 to oppose the neutral policy of the United States. 65438+1 October1obtained American citizenship.
May 1943, joined the work of the United States Admiralty as a scientific consultant.
1944, in order to support the anti-fascist war, 1905 manuscript of special relativity was auctioned for $6 million.
1947 continues to make a lot of remarks about world government.
1949, 1 month, he wrote Critical Answers to criticize the criticism of Copenhagen School in the collection Albert Einstein: Philosopher-Scientist.
In February 1950, 13, he made a televised speech against American-made hydrogen bombs. Signed and sealed the will on March 65438, 2008.
195 1 year, he published articles and letters one after another, pointing out that the U.S. policy of armament expansion is a serious obstacle to world peace.
1 952165438+1October,1After the death of Israeli President weismann, the Israeli government asked him to be the second president, but he was rejected.
1954 was denounced as "the enemy of America" by US Senator McCarthy in March.
1955 died in the hospital on April 18 1: 25.
A long and difficult exploration
After the completion of the general theory of relativity, Einstein still felt dissatisfied, so he wanted to extend the general theory of relativity to include not only the gravitational field, but also the electromagnetic field. He believes that this is the third stage of the development of relativity, namely the unified field theory.
After 1925, Einstein went all out to explore the unified field theory In the first few years, he was optimistic that victory was in sight; It turned out to be a lot more difficult. He thinks that the existing mathematical tools are not enough. Exploration of 1928 to pure mathematics. He tried various methods, but he didn't get any results with real physical significance.
During the 30 years from 1925 to 1955, except for the completeness of quantum mechanics, gravitational waves and general relativity, Einstein devoted almost all his scientific creative energy to the exploration of unified field theory.
1937, with the cooperation of two assistants, he deduced the equation of motion from the gravitational field equation of general relativity, further revealing the unity of time and space, matter and motion, which was a major development of general relativity and the last major achievement Einstein made in scientific creation activities.
He never succeeded in the unified field theory. He never gets discouraged and always starts from scratch with confidence. Because he was far away from the mainstream of physics research at that time, he went alone to overcome the problems that could not be solved at that time. So contrary to the situation in the 1920s, he was very isolated in physics in his later years. However, he is still fearless and unswervingly follows his own path. Until the day before his death, he was still in his hospital bed preparing to continue his mathematical calculation of the unified field theory.
Concerned about the fate of all mankind.
Einstein loved science as well as human beings. He didn't isolate himself from society because he was immersed in scientific research. He always cared about human civilization and progress and fought bravely for it. He said, "One can only find the meaning of a short and risky life if he devotes himself to society", and he did it himself.
1914 In April, Einstein accepted the invitation of the German scientific community and moved to Berlin. In August, World War I broke out. Although he lived in the birthplace of war and was surrounded by war advocates, he firmly showed his anti-war attitude. In September, Einstein participated in launching the anti-war group "New Motherland Alliance". Although the organization was declared illegal and a large number of its members were arrested and persecuted and went underground, Einstein resolutely participated in the secret activities of the organization.
On June+10, 5438, under the manipulation and instigation of militarists, the German scientific and cultural circles published the Declaration of Civilized World, defending the war of aggression launched by Germany, arguing that Germany is above all else and the whole world should accept the "true German spirit". Ninety-three people signed the declaration, all of whom were prestigious scientists, artists and priests in Germany at that time. Even Nernst, Roentgen, ostwald and Planck signed it. When asked for Einstein's autograph, he flatly refused, but at the same time resolutely signed his name on the anti-war letter to Europeans. This move shocked the whole world.
19 17. After the victory of the Soviet socialist revolution led by Lenin, Einstein enthusiastically supported this great revolution and praised it as a great social experiment that will be decisive for the whole world. He said: "I respect Lenin because he is a man with complete self-sacrifice spirit and devoted himself wholeheartedly to realizing social justice. I don't think his method is practical, but one thing is certain: people like him are defenders and reconstructors of human conscience. "
19181kloc-0/October, German workers and soldiers, influenced and inspired by the victory of the October Revolution in Russia, launched an uprising and overthrew the German emperor William II. On the third day after stepping down, Einstein wrote two postcards to his mother, cheering "a great event happened ... what an honor to experience it personally!" "
From the 1920s to the early 1930s, Einstein was basically an absolute pacifist. However, the fact that wars of aggression and plunder are constantly happening has broken his beautiful dream. Especially after Hitler came to power in 1933, Germany became increasingly fascist, which made Einstein realize that a new barbaric war was inevitable and prompted him to change his point of view. He made it clear: "When the law and human dignity must be defended, we must fight. Since the danger of fascism came, I no longer believe that absolute negative pacifism is effective. As long as fascism rules Europe, there will be no peace. "
Because of Einstein's progressive activities and because he was a Jew, he was listed as an important persecution object by the German Nazis. Fortunately, he left Germany to give lectures in the United States at the end of 1932 and was not killed. His house in Berlin was raided and destroyed, his property was confiscated and his works were burned. The Nazis offered a reward of 20,000 marks to kill him. Faced with the danger of Nazi assassination, Einstein did not have the slightest fear, but fought more resolutely. When his close friend Laue wrote to persuade him to take a wise attitude on political issues, he ignored his personal safety and shouted, pointing out that fascism means war, and peace must be defended by armed forces, calling on the American people to rise up against fascism.
Einstein was very sad when he later learned on the radio that the United States dropped atomic bombs on Hiroshima and Nagasaki, causing many civilian casualties. Later, he wrote a letter to American citizens, in which he said: "We scientists who liberated this great power should give priority to taking responsibility for everything, and must limit that atomic energy should never be used to kill all mankind, but should be used to enhance human happiness." From 65438 to 0955, Einstein and Russell jointly published the Russell-Einstein Declaration, which opposed nuclear war and called for world peace.
1949, Einstein wrote an article "Why is socialism? Newspapers. Here, he put forward a view that seems to be correct now! "Planned economy is socialism. The planned economy itself may be accompanied by complete slavery of individuals. The establishment of socialism needs to solve some extremely difficult social and political problems. In view of the high concentration of political power and economic power, how can we prevent administrative personnel from becoming unlimited and arrogant? How to ensure a democratic balance for administrative power while protecting individual rights? "
Superstar fall
1955 On April 8th, Albert Einstein, the greatest scientist in human history, died in Princeton, USA due to ruptured aortic aneurysm.
anecdote
■ Einstein played truant.
1895 spring, Einstein 16 years old. According to the laws of Germany at that time, only when the boy left Germany before the age of 17 could he not have to come back for military service. Because he hated militarism and couldn't bear to stay in the barracks alone-just like Louis Polder Middle School, Einstein decided to leave Germany and go to Italy to reunite with his parents without consulting his parents.
However, what if I drop out of school and can't get my diploma later? Einstein, who has always been honest and simple, came up with a self-righteous idea in a hurry. He asked the math teacher to give him a certificate to prove that his math scores were excellent and he reached the university level early. I got a sick note from a familiar doctor, saying that it was neurasthenia and I needed to go home and rest. Einstein thought that with these two proofs, he could escape from this disgusting place.
Who knows, before he applied, the dean called him and ordered him to drop out of school on the grounds that he corrupted the class spirit and disobeyed the school discipline. Einstein blushed. For whatever reason, he was willing to leave this middle school and didn't care about anything. He just suddenly felt guilty that he had come up with a cunning idea but it didn't come true. Einstein felt guilty every time he mentioned it later. Perhaps this kind of thing is far from his frank and sincere personality.
■ Refuse to be the second president of Israel.
1948 14 in may, the state of Israel was born, but soon war broke out between Israel and neighboring Arab countries. Einstein, who has lived in the United States for more than ten years, immediately declared to the media: "Now, the Israelis can't retreat any more. We should fight. Jews can only survive in a world hostile to them if they rely on themselves. " 1952165438+1On October 9th, Weizmann, an old friend of Einstein and the first president of Israel, passed away. The day before, the Israeli ambassador to the United States handed Einstein a letter from Israeli Prime Minister Ben Gurion, formally asking Einstein to become the Israeli presidential candidate. That evening, a reporter called Einstein's residence and asked Einstein, "I heard that you will be appointed as the president of Israel, professor." Will you accept it? " "No, I can't be president." "The President doesn't have many specific affairs, and his position is symbolic. Professor, you are the greatest Jew. No, no, you are the greatest person in the world. If you are the president of Israel and symbolize the greatness of the Jewish nation, that would be great. " "No, I can't." Hardly had Einstein put down the phone when it rang again. This time it's the Israeli ambassador to Washington. The ambassador said, "Professor, I was instructed by Israeli Prime Minister Ben Gurion. Are you willing to accept your nomination as a presidential candidate? " "Mr. Ambassador, I know a little about nature and know almost nothing about people. How can a man like me be president? Please explain to the press and give me a hand. " The ambassador further persuaded: "Professor, the late President Weizmann was also a professor. You can do it. " "Weizmann and I are different. He can do it, I can't. " "Professor, every Israeli citizen and every Jew in the world is waiting for you!" Einstein was really moved by the kindness of his compatriots, but he was more concerned with how to politely refuse the ambassador and the Israeli government without letting them down or embarrassed. Soon, Einstein issued a statement in the newspaper, formally refusing to be the president of Israel. In Einstein's view, "being president is not an easy task." At the same time, he quoted himself again: "Equation is more important to me, because politics is present, but equation is eternal."
■ How did Einstein approach China?
As early as 19 19, Einstein's theory of relativity was introduced to China, especially the British philosopher Russell came to China to give lectures in 1920, which left a deep impression on China academic circles. Einstein's own eyes again and again projected to the ancient and unfamiliar China. /kloc-in the winter of 0/922, he was invited to give lectures in Japan. On his way back and forth, he passed through Shanghai twice and stayed for three days. He saw China in distress with his own eyes and expressed deep sympathy. In his travel diary, he wrote down the "tragic picture" and his feelings: "Externally, China people are famous for their hard work and their low requirements for lifestyle and children's welfare. They are more optimistic and naive than Indians. But most of them have a heavy burden: men and women knock stones every day for five cents a day. They seem too slow to understand their terrible fate. " "Einstein saw this labor, groaning and tenacious nation, and his social sympathy was awakened again. He thinks this is the poorest country on earth. They were brutally abused and treated worse than cattle and horses. " (Collected Works of Einstein, edited by Xu, Commercial Press, 1979, pages 20 and 2 1) More than ten years later (1936), Einstein said in his first individual conversation with Zhou Peiyuan who came to Princeton University in the United States: "The people of China are suffering people." His sympathy is sincere and heartfelt, not in words, but in action.
The September 18th Incident took place in 193 1, and Japanese ambitions of invading China from the northeast were obvious. At that time, the international community showed helplessness and incompetence. On June 1 1, Einstein publicly condemned Japan's aggression against the three northeastern provinces and called on all countries to unite to impose economic sanctions on Japan. 1932 10, "Commander-in-Chief of the May 4th Movement" (in Mao Zedong) and Chen Duxiu, founder of China's * * * production party (who was expelled from the party at that time), were arrested in Shanghai. He and Russell, Dewey and other internationally renowned intellectuals jointly called Chiang Kai-shek to demand his release. 1in March, 937, after Shen Junru, Zhang Naiqi, Wang Zaoshi, Shi Liang and other "seven gentlemen" who advocated anti-Japanese were imprisoned, they joined forces with Dewey, Meng Lu and other famous intellectuals to rescue them by electricity, exerting moral pressure on the Kuomintang authorities. 1In June, 938, in order to help War of Resistance against Japanese Aggression in China, he and the eldest son of President Roosevelt launched the "China Aid Committee" and launched fundraising activities for China aid in 2,000 towns in the United States.
Einstein is a true citizen of the world, and his love has no national boundaries. His feelings for China are not utilitarian, but are entirely based on human sympathy and strong humanitarian feelings. His thoughts also had a profound influence on China. Shortly after the September 18th Incident, Xu, a teenager who was still in Grade Two, was an ardent admirer of him, hoping to become a scientist like him when he grew up. 1934, Einstein's collection My World View was published in Europe. A few years later (1937 on the eve of the Anti-Japanese War), it was translated by Ye Yunli, a physics professor studying in France, according to the French translation. Because of the national disaster, this book didn't arouse much response, but young Xu was lucky enough to buy a copy before 1938 went to college. He began to seriously think about the meaning of life and the relationship between people and the country. Einstein's many words of wisdom made him unforgettable all his life, and Einstein's image has always played an important role in his later life. 1955, after Einstein's death, Xu and Zhou Peiyuan both published mourning articles. Unfortunately, in the eight years from 1968 to 1976, Einstein became "the biggest reactionary bourgeois academic authority in the field of natural science since this century" in China, and the Gang of Four set off an absurd movement to criticize Einstein. Fortunately, most scientists ignore it and actually resist it. 1979, Beijing also held a grand commemorative meeting for Einstein's birthday100th anniversary.
Einstein and Relativity
■ The establishment of special relativity
As early as 16 years old, Einstein learned from books that light is a very fast electromagnetic wave. He has an idea. If a person moves at the speed of light, what kind of world scene will he see? He will not see the advancing light, but only the electromagnetic field that oscillates in space but stagnates. Is this possible?
In connection with this, he would like to discuss the so-called ether problem related to light waves. The word ether comes from Greece and is used to represent the basic elements that make up objects in the sky. /kloc-Descartes introduced it into science for the first time in the 0/7th century as a medium for spreading light. Later, Huygens further developed the theory of ether, thinking that the medium carrying light waves is ether, which should fill all spaces including vacuum and penetrate into ordinary matter. Unlike Huygens, Newton put forward the particle theory of light. Newton believed that the luminous body emitted a stream of particles moving in a straight line, and the impact of the particle stream on the retina caused vision. Newton's particle theory prevailed in18th century, but the wave theory prevailed in19th century, and the theory of ether developed greatly. At that time, the view was that the propagation of waves depended on the medium, because light can propagate in a vacuum, and the medium that propagates light waves is the ether that fills the whole space, also called optical ether. At the same time, electromagnetism has developed vigorously. With the efforts of Maxwell, Hertz and others, a mature electromagnetic phenomena's dynamic theory-electrodynamics was formed, which unified light and electromagnetic phenomena in theory and practice, and regarded light as electromagnetic waves in a certain frequency range, thus unifying the wave theory of light and electromagnetic theory. Ether is not only the carrier of light waves, but also the carrier of electromagnetic fields. Until the end of 19, people tried to find ether, but they never found it in the experiment.
But electrodynamics has encountered a big problem, which is inconsistent with the relativity principle followed by Newtonian mechanics. The theory of relativity existed as early as Galileo and Newton. The development of electromagnetism was originally included in the framework of Newtonian mechanics, but it encountered difficulties in explaining the electromagnetic process of moving objects. According to Maxwell's theory, the speed of electromagnetic waves in vacuum, that is, the speed of light, is a constant. However, according to the principle of speed addition in Newtonian mechanics, the speed of light in different inertial systems is different, which leads to a question: Is the principle of relativity applicable to mechanics applicable to electromagnetism? For example, there are two cars, one is approaching you and the other is leaving. You saw the lights of the previous car.