Albert Einstein (March 14, 1879 - April 18, 1955), a world-famous German-American scientist, the founder and founder of modern physics . On December 26, 1999, Einstein was selected as the "Great Man of the Century" by the American "Time" magazine
Einstein graduated from the Technical University of Zurich in 1900 and became a Swiss citizen. Received a doctorate in philosophy from the University of Zurich in 1905. Served at the Patent Office in Bern. Professor at the Technical University of Zurich and Deutsche University in Prague. Returning to Germany in 1913, he served as director of the Kaiser Wilhelm Institute of Physics in Berlin and professor at the University of Berlin, and was elected as an academician of the Prussian Academy of Sciences. In 1933, he was persecuted by the Nazi regime and moved to the United States. He became a professor at the Institute for Advanced Study in Princeton and engaged in theoretical physics research. He became a U.S. citizen in 1940.
The late nineteenth century was a period of change in physics. Starting from experimental facts, Einstein re-examined the basic concepts of physics and made fundamental breakthroughs 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, the theory of stellar atmospheres, was built on the basis of 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 sources. In recent years, more and more high-energy physical phenomena have been discovered, and special relativity has become one of the most basic theoretical tools to explain such phenomena. His general theory of relativity also solved a long-standing mystery in astronomy and deduced the phenomenon of light bending that was later verified. It also became the theoretical basis for many later astronomical concepts.
Einstein's greatest contribution to astronomy is his cosmological theory. He founded relativistic cosmology, established a static finite and boundless self-consistent dynamic universe model, and introduced new concepts such as cosmological principles and curved space, which greatly promoted the development of modern astronomy.
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At 11:30 am on March 14, 1879, Einstein was born at No. 135 Bahnhofstrasse, Ulm, Germany. Both parents are Jewish. His father's name was Hermann Einstein, and his mother's name was Pauline Coker. Einstein
In 1884, Einstein became fascinated with the pocket compass.
In 1885, Einstein began to learn violin.
In 1886, Einstein studied at the Munich Public School (Council School); he studied Jewish observances at home.
In 1888, Einstein entered Louis Pold High School. Continue to receive religious education in school and receive a ordination ceremony. Friedman is the instructor.
In 1889, under the guidance of Talmei, a medical student, he read popular scientific readings and philosophical works.
In 1891, he taught himself Euclidean geometry and felt passionate about it. At the same time, he began to teach himself advanced mathematics.
In 1892, he began to read the works of Immanuel Kant. In 1895, he taught himself calculus.
In 1896, he received a diploma from Aarau High School. In October, he entered the Normal Department of the Federal Technical University of Zurich to study physics.
On October 19, 1899, Einstein officially applied for Swiss citizenship.
In August 1900, Einstein graduated from the Federal University of Technology in Zurich; in December he completed his thesis "Inferences from Capillary Phenomenon", which was published in the "Journal of Physics" in Leipzig the following year and became a Swiss citizen.
On March 21, 1901, he obtained Swiss nationality. From May to July of this year, I completed the thesis on the thermodynamic theory of electric potential difference.
In September 1904, he was converted from a probationary employee of the Patent Office to a formal third-level technician.
In March 1905, he developed quantum theory, proposed the light quantum hypothesis, and solved the photoelectric effect problem. In April, he submitted his thesis "A New Method for Determining Molecular Size" to the University of Zurich and obtained his doctorate.
In May, he completed the paper "On the Electrodynamics of Moving Bodies" and independently and completely proposed the principle of special relativity, creating a new era in physics.
In April 1906, he was promoted to a second-level technician in the Patent Office. In November, I completed a paper on the specific heat of solids, which is the first paper on the quantum theory of solids. In October 1908, he concurrently served as a non-staff lecturer at the University of Bern.
In October 1909, he left the Bern Patent Office and became an associate professor of theoretical physics at the University of Zurich. Einstein
In October 1910, he completed his paper on critical opalescence.
The law of "photochemical equivalent" was proposed in 1912.
In 1913, he returned to Germany and served as director of the Kaiser Wilhelm Institute of Physics in Berlin and professor at the University of Berlin. He was also elected as an academician of the Prussian Academy of Sciences.
In April 1914, Einstein accepted the invitation from the German scientific community and moved to Berlin.
In August, World War I broke out. Although he lived in the birthplace of the war and lived surrounded by war advocates, he resolutely expressed his anti-war attitude.
In September, Einstein participated in the founding of the anti-war group "New Motherland Alliance". When this organization was declared illegal and its members were arrested and persecuted in large numbers and went underground, Einstein remained determined Participate in the secret activities of this organization.
In October, under the control and instigation of militarists, the German scientific and cultural circles issued the "Declaration of a Civilized World" to defend the aggressive war launched by Germany and advocated that Germany was above all else and that all The world should embrace the "true German spirit". Ninety-three people signed the "Declaration", all of whom were prestigious German scientists, artists, and pastors at the time. Even Nernst, Roentgen, Ostwald, Planck, etc. all signed it. When Einstein was asked to sign, he flatly refused, but at the same time he resolutely signed his name on the anti-war "Letter to Europeans." This move shocked the world.
In November 1915, he proposed the complete form of the gravity equation of general relativity and successfully explained the perihelion motion of Mercury. Einstein
In March 1916, he completed the concluding paper "Foundations of General Relativity". In May, he proposed the hypothesis that the universe is finite and unbounded. In August, he completed "Quantum Theory of Radiation", summarizing the development of quantum theory and proposing the theory of stimulated emission.
After the victory of the Soviet socialist revolution led by Lenin in 1917, Einstein enthusiastically supported this great revolution and praised it as a great social experiment that would be of decisive significance to the world. : "I respect Lenin because he was a person who had a spirit of complete self-sacrifice and devoted himself wholeheartedly to realizing social justice. I don't think his methods are practical, but one thing is for sure: people like him are He is the defender and recreater of human conscience.”
In November 1918, influenced and inspired by the victory of the Russian October Revolution, German workers and soldiers launched an uprising and overthrew Kaiser Wilhelm. On the third day after II stepped down, Einstein wrote two postcards to his mother, cheering "A great thing has happened... What an honor it is to experience this event personally!" In the 1920s and early 1930s, , Einstein was basically an absolute pacifist. However, the reality of constant wars of aggression and plunder shattered 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, prompting him to change his views. He made it clear: "When the law and human dignity must be defended, we must fight. Since the danger of fascism has arrived, I no longer believe that absolute passive pacifism is effective. As long as fascism rules Europe, then There will be no peace." Because of Einstein's progressive activities and because he was a Jew, he was listed as an important target of persecution by the German Nazis. Fortunately, he left Germany at the end of 1932 to give lectures in the United States and was not persecuted. His house in Berlin was raided and destroyed, his property confiscated, his books burned, and the Nazis offered a reward of 20,000 marks for his death. Facing the danger of assassination by the Nazis, Einstein showed no fear, but fought more determinedly.
When his close friend Laue wrote a letter to persuade him to adopt a prudent and protective attitude towards political issues, he regardless of his personal safety, loudly pointed out that fascism means war, peace must be defended with arms, and called on the American people to rise up and fight fascism. When Einstein later learned from radio broadcasts that the United States had dropped atomic bombs on Hiroshima and Nagasaki, killing and injuring many civilians, he felt very sad. He later wrote a letter to American citizens, saying: "The scientists who have liberated this huge power must first take responsibility for everything. Atomic energy must be limited and must not be used to kill all mankind, but To enhance human happiness."
Einstein's theory in 1919 is regarded as "one of the greatest achievements in the history of human thought." In December, he received the only honorary degree in Germany: a doctorate in medicine from the University of Rostock.
From April 2 to May 30, 1921, in order to raise funds for the establishment of the Hebrew University of Jerusalem, he and Weizmann visited the United States for the first time.
In January 1922, the first paper on unified field theory was completed. In July, he was threatened with murder and temporarily left Berlin. On October 8, Einstein and Elsa took a ship from Marseille to Japan. Visits Colombo, Singapore, Hong Kong and Shanghai along the way. On November 9, while on his way to Japan, Einstein was awarded the 1921 "Nobel Prize in Physics". Visited Japan from November 17th to December 29th.
In July 1923, he went to Gothenburg to receive the 1921 Nobel Prize. In December, it was speculated for the first time that quantum effects may arise from over-constrained general relativistic field equations.
In 1924, the "Bose-Einstein condensation" was discovered.
After 1925, Einstein went all out to explore the unified theory. In the first few years, he was very optimistic and thought victory was in sight; later he found difficulties and he believed that the existing mathematical tools were not enough.
In the 30 years from 1925 to 1955, in addition to the completeness of quantum mechanics, gravitational waves and the motion problems of general relativity, Einstein devoted almost all of his scientific and creative energy to The search for unified field theory.
In 1926, he was elected as an academician of the Soviet Academy of Sciences.
After 1928, he turned to the exploration of pure mathematics. He tried various methods, but failed to achieve results of real physical significance.
In January, he was elected as a director of the "German Human Rights League" (formerly the German "New Fatherland League").
On his 50th birthday in March 1929, he hid in the countryside to avoid birthday celebrations. Won the "Planck Medal" on June 28.
From December 11, 1930 to March 4, 1931, Einstein visited the United States for the second time, giving lectures at the California Institute of Technology.
In July 1932, he corresponded with Freud to discuss the psychological issues of war; he called on the German people to rise up to defend the Weimar Republic and oppose fascism with all their strength.
On January 30, 1933, the Nazis came to power.
On March 10, he issued a statement in Pasadena that he would not return to Germany, and set off back to Europe the next day.
On March 20, the Nazis raided his house and he protested. Later, his property in Germany was confiscated and his books were burned.
In May 1935, he formally applied for permanent residence in the United States in Bermuda. That year, he was running around in order to give the Nobel Prize (Peace Prize) to Ossietzky, who was imprisoned in the Nazi concentration camp.
In March 1937, he supported China's "Seven Gentlemen".
In 1937, with the cooperation of two assistants, he derived the equations of motion from the gravitational field equations of general relativity, further revealing the unity between space, time, matter, and motion. This is the generalized theory of The major development of the theory of relativity was also the last major achievement achieved by Einstein in his scientific creation activities. In terms of unified field theory, he never succeeded. He never got discouraged and started from the beginning with full confidence every time. Because he stayed away from the mainstream of physics research at that time and attacked problems on his own that were unsolvable at the time, he was very isolated in the physics community in his later years, contrary to his situation in the 1920s.
However, he remained fearless and unswervingly followed the path he had identified. Until the day before his death, he was still preparing to continue his mathematical calculations on the unified field theory in his hospital bed. Concerned about the destiny of all mankind, Einstein loved science and mankind. He did not put himself outside society because he was immersed in scientific research. He has always been concerned about human civilization and progress, and fought tenaciously and bravely for it. He said: "Only by dedicating oneself to society can one find out the meaning of a life that is actually short and risky." This is exactly what he did.
In September 1938, he wrote a letter to his descendants five thousand years later, expressing his dissatisfaction with the current situation of capitalist society.
On August 2, 1939, he wrote to President Roosevelt, suggesting that the United States speed up atomic energy research to prevent Germany from mastering the atomic bomb first.
On May 22, 1940, he called Roosevelt to oppose the U.S. neutrality policy.
Obtained U.S. citizenship on October 1.
In May 1943, he participated in the work of the U.S. Navy as a scientific advisor.
In 1944, in order to support the anti-fascist war, he auctioned the manuscript of the 1905 special theory of relativity paper for US$6 million.
In 1947, he continued to publish a lot of remarks about world government.
In January 1949, he wrote "Reply to Criticism", a counter-criticism of the Copenhagen School's criticism in the collection "Albert Einstein: Philosopher-Scientist".
On February 13, 1950, he gave a televised speech opposing the United States' efforts to build a hydrogen bomb. On March 18, the will was signed and sealed.
In 1951, he published a series of articles and letters pointing out that the United States' policy of arms expansion and war preparation was a serious obstacle to world peace.
In November 1952, after the death of Weisman, the first president of Israel, the Israeli government asked him to serve as the second president, but he was rejected.
In March 1954, he was publicly denounced as an "enemy of the United States" by U.S. Senator McCarthy.
In 1955, Einstein and Russell jointly issued the "Russell-Einstein Declaration" opposing nuclear war and calling for world peace.
He died in the hospital at 1:25 on April 18, 1955. After the long and arduous exploration of the general theory of relativity, Einstein still felt dissatisfied and wanted to extend the general theory of relativity to include not only the gravitational field, but also the electromagnetic field. He believed that this was the third stage in the development of relativity, that is, unified field theory.
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■The creation of the special theory of relativity
As early as 16 years old, Einstein learned from books that light is very He came up with the idea of ??electromagnetic waves traveling at a fast speed. If a person moved at the speed of light, what kind of world would he see? He will not be able to see the light moving forward, but can only see the electromagnetic field oscillating but stagnant in space. Is this possible?
In connection with this, he very much wanted to explore the so-called ether problem related to light waves. The term ether originates from the Greeks and is used to represent the basic elements that make up celestial objects. Descartes first introduced it to science in the 17th century as a medium for transmitting light. Later, Huygens further developed the ether theory, believing that the medium carrying light waves was ether, which should fill all space including vacuum, and be able to penetrate into ordinary matter. Different from Huygens' view, Newton proposed the particle theory of light. Newton believed that the luminous body emits a stream of particles moving in a straight line, and the particle stream impacts the retina to cause vision. In the 18th century, Newton's particle theory prevailed. However, in the 19th century, the wave theory gained absolute dominance, and the theory of ether also developed greatly. The view at that time was that the propagation of waves depends on the medium, because light can propagate in vacuum, and the medium for propagating light waves is the ether that fills the entire space, also called light ether. At the same time, electromagnetism has developed vigorously. Through the efforts of Maxwell, Hertz and others, a mature dynamic theory of electromagnetic phenomena—electrodynamics—has been formed, and unified light and electromagnetic phenomena in theory and practice. It is believed that Light is an electromagnetic wave within a certain frequency range, thus unifying the wave theory of light with the electromagnetic theory. Ether is not only the carrier of light waves, but also the carrier of electromagnetic fields.
Until the end of the 19th century, people attempted to search for ether, but it was never discovered experimentally.
However, electrodynamics has encountered a major problem, which is that it is inconsistent with the principle of relativity followed by Newtonian mechanics. The idea of ??the principle of relativity existed as early as the time of Galileo and Newton. The development of electromagnetism was initially integrated into 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 speed addition principle of Newtonian mechanics, the speed of light in different inertial systems is different. This raises a question: Is the principle of relativity applicable to mechanics Applicable to electromagnetism? For example, there are two cars, one approaching you and one driving away. You see the lights of the car in front of you approaching you and the lights of the car behind you moving away. According to Maxwell's theory, the speed of the two kinds of light is the same, and the speed of the car does not play a role in this. But according to Galileo's theory, these two measurements are different. The car coming towards you will accelerate the light emitted, that is, the speed of light of the car in front = speed of light + speed of car; while the speed of light of the car driving away is slower, because the speed of light of the car behind = speed of light - speed of car. Maxwell's and Galileo's statements about speed clearly contradicted each other. How do we resolve this disagreement?
Theoretical physics reached its peak in the 19th century, but it also contained huge crises. The discovery of Neptune showed the extremely powerful theoretical power of Newtonian mechanics. The unity of electromagnetism and mechanics made physics show a formal integrity, and it was praised as "a solemn and majestic architectural system and a touching and beautiful temple." In people's minds, classical physics has reached an almost perfect level. When the famous German physicist Planck was young, he told his teacher that he would devote himself to theoretical physics. The teacher advised him: "Young man, physics is a science that has been completed, and there will be no more great achievements." It is a pity to devote his life to this subject."
Einstein seems to be the person who will build a new edifice of physics. During his days at the Bern Patent Office, Einstein paid extensive attention to the cutting-edge developments in physics, thought deeply about many issues, and formed his own unique insights. During the course of ten years of exploration, Einstein carefully studied Maxwell's electromagnetic theory, especially electrodynamics as developed and elaborated by Hertz and Lorentz. Einstein firmly believed that the electromagnetic theory was completely correct, but there was one problem that made him uneasy, which was the existence of the absolute reference system ether. He read many works and found that all attempts to prove the existence of ether had failed. After research, Einstein discovered that, apart from serving as an absolute reference system and a load of electromagnetic fields, ether had no practical significance in Lorentz's theory. So he thought: And is an absolute frame of reference necessary? Does the electromagnetic field have to have a load?
Einstein liked to read philosophical works and absorb ideological nourishment from philosophy. He believed in the unity of the world and the consistency of logic. The principle of relativity has been widely proven in mechanics, but it cannot be established in electrodynamics. Einstein raised doubts about the logical inconsistency between the two theoretical systems of physics. He believed that the principle of relativity should be universally true, so the electromagnetic theory should have the same form for each inertial system, but here the problem of the speed of light arises. Whether the speed of light is a constant quantity or a variable quantity has become the primary question of whether the principle of relativity is universally valid. Physicists at that time generally believed in the ether, that is, they believed in the existence of an absolute reference system. This was influenced by Newton's concept of absolute space. At the end of the 19th century, Mach criticized Newton's absolute view of space and time in his book "Developing Mechanics", which left a deep impression on Einstein. One day in May 1905, Einstein discussed this issue that had been explored for ten years with a friend Besso. Besso elaborated on his views based on Machism, and the two discussed it for a long time. Suddenly, Einstein realized something. After thinking about it over and over again when he got home, he finally figured out the problem. The next day, he came to Besso's house again and said: Thank you, my problem is solved. It turns out that Einstein thought one thing clearly: there is no absolute definition of time, and there is an inseparable connection between time and the speed of light signals. He found the key to the lock, and after five weeks of hard work, Einstein presented the special theory of relativity to people.
On June 30, 1905, the German "Annals of Physics" accepted Einstein's paper "On the Electrodynamics of Moving Bodies" and published it in the journal in September of the same year.
This paper is the first article on the special theory of relativity. It contains the basic ideas and basic content of the special theory of relativity. Special relativity is based on two principles: the principle of relativity and the principle of the constant speed of light. The starting point for Einstein's solution to the problem was his firm belief in the principle of relativity. Galileo was the first to clarify the idea of ??the principle of relativity, but he did not give a clear definition of time and space. Newton also talked about the idea of ??relativity when he established the mechanical system, but he also defined absolute space, absolute time and absolute motion. He was contradictory on this issue. Einstein greatly developed the principle of relativity. In his view, there is no absolutely static space at all, and there is no absolutely identical time. All time and space are related to moving objects. For any reference system and coordinate system, there is only space and time belonging to this reference system and coordinate system. For all inertial systems, the physical laws expressed by the space and time of this reference system are all in the same form. This is the principle of relativity, strictly speaking, the principle of relativity in a narrow sense. In this article, Einstein did not discuss much about the basis for the constant speed of light as a basic principle. He proposed that the constant speed of light was a bold assumption, which was based on the requirements of electromagnetic theory and the principle of relativity. This article is the result of Einstein's many years of thinking about the issue of ether and electrodynamics. He used the relativity of simultaneousness as a breakthrough to establish a new theory of time and space, and based on the new theory of space and time, he gave the theory of moving bodies Electrodynamics in its complete form, the ether is no longer necessary, ether drift is non-existent.
What is the relativity of simultaneity? How do we know that two events in different places happened at the same time? Generally, we confirm via signals. In order to know the simultaneity of events in different places, we need to know the speed of signal transmission, but how come this speed is not exceeded? We must measure the spatial distance between two places and the time required for signal transmission. Measuring spatial distance is very simple. The trouble lies in measuring time. We must assume that there is a clock in each place that has been adjusted. From the readings of the two clocks, The time it takes for the signal to propagate can be known. But how do we know that the clock in a different place is correct? The answer is that a signal is also needed. Can this signal set the clock correctly? If we follow the previous line of thinking, it would require a new signal, which would lead to infinite retreat and the simultaneity of different places cannot actually be confirmed. But one thing is clear, simultaneity must be related to a signal, otherwise it would be meaningless for us to say that these two things happened at the same time.
The light signal may be the most suitable signal for the clock, but the speed of light is not infinite, which leads to a novel conclusion. For a stationary observer, two things happen at the same time, and for a moving observer, two things happen at the same time. It's not at the same time. We imagine a train running at high speed, its speed is close to the speed of light. When the train passed the platform, A stood on the platform. Two lightning bolts flashed in front of A's eyes, one at the front end of the train and one at the rear end, leaving traces on both ends of the train and corresponding parts of the platform. Through measurement, A and The distance between the two ends of the train is equal, and the conclusion is that A saw two lightning bolts at the same time. Therefore, for A, if the two received light signals travel the same distance within the same time interval and arrive at his location at the same time, the two events must occur at the same time, they are simultaneous. But for B, who is in the center of the train, the situation is different. Because B moves with the high-speed train, he will first intercept the front-end signal propagating towards him, and then receive the optical signal from the back-end. For B, the two events are not simultaneous. That is to say, simultaneity is not absolute but depends on the motion state of the observer. This conclusion denies the absolute time and absolute space frameworks underlying Newtonian mechanics.
The theory of relativity holds that the speed of light is constant in all inertial reference systems and is the maximum speed at which objects move. Due to relativistic effects, the length of a moving object will become shorter and the time of a moving object will dilate. However, due to the problems encountered in daily life, the movement speed is very low (compared to the speed of light), and no relativistic effect can be seen.
Einstein established relativistic mechanics based on a radical change in the view of space and time, stating that mass increases with speed and approaches infinity as speed approaches the speed of light. He also gave the famous mass-energy relationship: E=mc2. The mass-energy relationship played a guiding role in the subsequent development of atomic energy.
■The establishment of the general theory of relativity
After Einstein published his first article on the special theory of relativity in 1905, it did not immediately arouse a great response. However, Planck, an authority in German physics, noticed his article and believed that Einstein's work was comparable to that of Copernicus. It was precisely because of Planck's promotion that the theory of relativity quickly became a topic of research and discussion. Einstein also attracted academic attention.
In 1907, Einstein followed the advice of his friends and submitted his famous paper to apply for a non-staff lecturer position at the Federal University of Technology, but the reply he received was that the paper was incomprehensible. Although Einstein was already very famous in the German physics community, he could not get a university teaching position in Switzerland. Many famous people began to complain about him. In 1908, Einstein finally got a non-staff lecturer. position and became an associate professor in the second year. In 1912, Einstein became a professor. In 1913, at Planck's invitation, he served as director of the newly established Kaiser Wilhelm Institute for Physics and as a professor at the University of Berlin.
During this period, Einstein was considering extending the established theory of relativity. For him, there were two problems that made him uneasy. The first is the problem of gravity. Special relativity is correct for the physical laws of mechanics, thermodynamics and electrodynamics, but it cannot explain the problem of gravity. Newton's theory of gravity is at a distance. The gravitational effect between two objects is transmitted instantaneously, that is, at an infinite speed. This conflicts with the field view based on the theory of relativity and the limit of the speed of light. The second is the problem of non-inertial frames. The special theory of relativity, like the previous laws of physics, only applies to inertial frames. But in fact it is difficult to find a true inertial frame. Logically speaking, all natural laws should not be limited to inertial systems, but must consider non-inertial systems. It is difficult for special relativity to explain the so-called twin paradox. The paradox is that there is a pair of twin brothers. The brother is sailing in a spaceship at a speed close to the speed of light. According to the relativistic effect, the high-speed clock slows down and waits for the brother. Back, the younger brother has become very old, because the earth has experienced decades. According to the principle of relativity, the spaceship moves at a high speed relative to the earth, and the earth also moves at a high speed relative to the spacecraft. The younger brother sees that the older brother is getting younger, and the older brother sees that the younger brother should also be younger. There is simply no answer to this question. In fact, the special theory of relativity only deals with uniform linear motion, and the brother must go through a process of variable speed motion to come back, which is something that the theory of relativity cannot handle. While people were busy understanding the special theory of relativity, Einstein was completing the general theory of relativity.
In 1907, Einstein wrote a long article on the special theory of relativity, "On the Principle of Relativity and Conclusions Drawn from It". In this article, Einstein mentioned equivalence for the first time. Since then, Einstein's ideas about the equivalence principle have continued to develop. He used the natural law that inertial mass and gravitational mass are proportional as the basis of the equivalence principle, and proposed that a uniform gravitational field in an infinitely small volume can completely replace the reference frame of accelerated motion. Einstein also proposed the concept of a closed box: no matter what method is used, an observer in a closed box cannot determine whether he is at rest in a gravitational field or in a space that is accelerating without a gravitational field. , this is the most commonly used statement to explain the equivalence principle, and the equality of inertial mass and gravitational mass is a natural corollary of the equivalence principle.
In November 1915, Einstein submitted four papers to the Prussian Academy of Sciences. In these four papers, he put forward new ideas, proved the precession of Mercury's perihelion, and gave Get the correct gravitational field equation. At this point, the basic problems of general relativity have been solved, and general relativity was born. In 1916, Einstein completed a long paper "The Foundation of General Relativity". In this article, Einstein first called the theory of relativity that was previously applicable to inertial frames special relativity, and classified the physical laws that are also true only for inertial frames. The principle is called the principle of special relativity, and further states the principle of general relativity: The laws of physics must hold true for any frame of reference that is moving in any way.
Einstein’s general theory of relativity believes that due to the existence of matter, space and time will be curved, and the gravitational field is actually a curved space-time. Einstein's theory of using the sun's gravity to curve space well explains the unexplained 43 seconds of Mercury's perihelion precession.
The second major prediction of general relativity is gravitational redshift, that is, the spectrum moves toward the red end in a strong gravitational field. In the 1920s, astronomers confirmed this in astronomical observations. The third major prediction of general relativity is that gravitational fields deflect light. The largest gravitational field closest to the earth is the gravitational field of the sun. Einstein predicted that if the light of distant stars passes over the surface of the sun, it will be deflected for 1.7 seconds. In 1919, at the instigation of the British astronomer Eddington, the United Kingdom sent two expeditions to two places to observe the total solar eclipse. After careful research, the final conclusion was that starlight did indeed occur near the sun at 1.7 seconds of deflection. The Royal Society and the Royal Astronomical Society officially read out the observation report, confirming that the conclusions of general relativity are correct. At the meeting, famous physicist and President of the Royal Society Thomson said: "This is the most significant achievement in the theory of universal gravitation since Newton's time." "Einstein's theory of relativity is one of the greatest achievements of human thought." one". Einstein became a news figure. In 1916, he wrote a popular introduction to relativity, "A Brief Introduction to the Special and General Theory of Relativity." By 1922, it had been reprinted 40 times and translated into more than a dozen languages. spread widely.