Albert. Introduction of Einstein
Albert. Albert. Einstein was a Jewish physicist.
Einstein was born in a Jewish family in Ulm, Germany on 1879. 1900 graduated from the Federal Institute of Technology in Zurich and became a Swiss citizen. 1905 received a doctorate from the University of Zurich. Einstein put forward the photon hypothesis and successfully explained the photoelectric effect. Therefore, he won the 192 1 Nobel Prize in physics and founded the special theory of relativity. General relativity was founded in 19 15.
Einstein laid a theoretical foundation for the development of nuclear energy and initiated a new era of modern science and technology, and was recognized as the greatest physicist after Galileo and Newton. 199965438+On February 26th, Einstein was elected? A great man of the century? .
Albert. Einstein characters experience
Reading period
From 65438 to 0888 (aged 9), Einstein entered Louis Polder High School. He received religious education and bar mitzvah at school, and Friedman was the instructor.
1889 (10 years old), reading popular science books and philosophical works under the guidance of medical college student Talme.
189 1 year-old (12-year-old) He taught himself Euclid geometry, and he was enthusiastic about it. At the same time, he began to teach himself advanced mathematics.
1892 (13 years old), began to read Kant's works.
1894 (15 years old), Einstein's family moved to Italy.
1895 (16 years old), taught himself calculus. In the same year, Einstein failed to pass the entrance examination of Swiss Institute of Technology. Einstein began to think about what a person would see when moving at the speed of light. Confused about the internal contradictions of classical theories.
1896 (17 years old), graduated from Alao Middle School. 10 year 10 On October 29th, Einstein moved to Zurich and studied at Swiss Institute of Technology.
1899 65438+1October19 (aged 20), Einstein formally applied for Swiss citizenship.
1900 (2 1 year) In August, Einstein graduated from the Federal Institute of Technology in Zurich, Switzerland; In February, 65438, he completed his thesis "Inference of Capillary Phenomenon", which was published in the Journal of Physics in Leipzig the following year and incorporated into Swiss nationality.
1901March 2 1 (22 years old), and obtained Swiss nationality. From May to July this year, I finished my thesis on the thermodynamic theory of potential difference.
After graduation
1902 June16 (aged 23), employed by the Patent Office in Bern, Switzerland.
1903 (24 years old), he and his college classmate mileva? Marek is married. They had their first child before they got married.
1September, 904 (25 years old), changed from a trainee in the patent office to a formal third-class technician.
1March, 905 (at the age of 26), he published quantum theory, put forward the light quantum hypothesis, and solved the photoelectric effect problem. 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. So this year is called? Einstein miracle year? .
1April, 906 (at the age of 27) was promoted to the second-class technician of the Patent Office. 165438+ 10, the paper on specific heat of solids was completed, which is the first paper on solid quantum theory.
1907 (aged 28) was promoted to the first-class technician of the patent office.
1908 (29 years old) 10 month, part-time lecturer at the University of Bern.
1909 (30 years old) 10 month, left the Berne patent office as an associate professor of theoretical physics.
19 10 years (3 1 year) 10 months, and finished the paper on critical opalescence.
19 1 1 year (32 years old), moved from Switzerland to Prague.
19 12 (33 years old), propose? Photochemical equivalent? Law.
19 13 (34 years old), returned to Germany, served as the director of the Institute of Physics of Emperor William in Berlin and a professor at Humboldt University in Berlin, and was elected as an academician of the Prussian Academy of Sciences.
Albert. Einstein's major achievements
Theory of relativity
The establishment of special relativity;
As early as 16 years old, Einstein learned from books that light is a fast electromagnetic wave. Related to this, he would like to discuss the so-called etheric 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 and Christianity in the 0/7th century? Huygens initiated and developed the theory of ether, believing that ether is the medium of light wave propagation, which is full of all spaces including vacuum and can penetrate into matter. Different from the ether theory, 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, and wave theory prevailed in19th century. The theory of ether has also made great progress: the propagation of waves needs medium, and the medium through which light propagates in vacuum is ether, 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, and it was proved theoretically and practically that light is electromagnetic wave 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. On the contrary, Michelson Morey's experiment found that ether was unlikely to exist.
The development of electromagnetism was originally contained in the framework of Newtonian mechanics, but when explaining the electromagnetic process of moving objects, it was found that it was inconsistent with the relativity principle followed by Newtonian mechanics. According to Maxwell's theory, the speed of electromagnetic wave in vacuum, that is, the speed of light, is a constant; However, according to the principle of velocity addition in Newtonian mechanics, the speed of light in different inertial systems is different. For example, two cars, one is approaching you and the other is leaving. You see the lights in the front car approaching you and the lights in the back car are far away. According to Galileo's theory, the car coming to you will emit light with a speed greater than C (vacuum light speed of 3.0x10 8m/s/s), that is, the light speed in front of the car = light speed+speed; The speed of light leaving the car is less than c, that is, the speed of light behind the car = speed of light-speed. However, according to Maxwell's theory, the speed of the car does not affect the propagation of light. To put it bluntly, regardless of cars, the speed of light is equal to C. Maxwell and Galileo's views on speed are obviously opposite!
Einstein seems to be the man who is going to build a brand-new physics building. Einstein carefully studied Maxwell's electromagnetic theory, especially the electrodynamics developed and expounded by Hertz and Lorenz. Einstein firmly believes that the electromagnetic theory is completely correct, but there is one problem that makes him uneasy, and that is the existence of the absolute reference frame ether. He read a lot of books and found that all the experiments that proved the existence of ether failed. After Einstein's research, it was found that ether had no practical significance in Lorentz theory except as an absolute reference system and the load of electromagnetic field.
Einstein likes reading philosophical works and absorbing ideological nutrition from philosophy. He believes in the unity of the world and the consistency of logic. Are you online? Olympia Academy of Sciences? David? David hume's doubts about the universal validity of causality influenced Einstein. The principle of relativity has been widely proved in mechanics, but it cannot be established in electrodynamics. Einstein questioned the logical inconsistency between the two theoretical systems of physics. He believes that the principle of relativity should be universally established, so the electromagnetic theory should have the same form for each inertial system, but there is a problem of the speed of light here. Whether the speed of light is constant or variable becomes the primary question whether the principle of relativity is universally established. Physicists at that time generally believed in ether, that is, there was an absolute frame of reference, which was influenced by Newton's concept of absolute space. /kloc-At the end of 0/9, Mach criticized Newton's absolute view of time and space in Mechanics in Development, which left a deep impression on Einstein. 1905 One day in May, Einstein and a friend Bezo discussed the problem that had been explored for ten years. Bezo expounded his point of view according to Mahism, and they had a long discussion about it. Suddenly, Einstein realized something, went home and thought about it again and again, and finally figured it out. The next day, he came to Bezo's house again and said, thank you, my problem has been solved. It turned out that Einstein thought clearly about one thing: there is no absolute definition of time, and time is closely related to the speed of optical signals. He found the key to the lock, and after five weeks of hard work, Einstein showed people the special theory of relativity.
1905 On June 30th, the German Yearbook of Physics accepted Einstein's paper "On Electrodynamics of Moving Objects" and published it in September of the same year. This paper is the first article about special relativity, which contains the basic ideas and contents of special relativity. Special relativity is based on two principles: the principle of relativity and the principle of invariability of light speed. Einstein's starting point for solving problems is to firmly believe in the principle of relativity. Galileo first expounded the idea of relativity principle, but he did not give a clear definition of time and space. Newton also talked about relativity when he established the mechanical system, but he also defined absolute space, absolute time and absolute motion. He contradicts himself on this issue. Einstein greatly developed the principle of relativity. In his view, there is no absolute still space, and there is no absolute constant time. All time and space are connected with 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 in space and time of the reference system are the same in form, which is the principle of relativity, strictly speaking, the principle of relativity in a narrow sense. In this article, Einstein did not discuss the constant speed of light as the basis of the basic principle. It is a bold assumption that the speed of light is constant, which is put forward from the requirements of electromagnetic theory and relativity principle. This article is the result of Einstein's thinking about ether and electrodynamics for many years. At the same time, he established a brand-new space-time theory from the perspective of relativity, and gave a complete form of electrodynamics of moving objects on the basis of this new space-time theory. Ether is no longer necessary and ether drift does not exist.
What is the relativity of simultaneity? How do we know that events in two different places happen at the same time? Generally speaking, we will confirm by signal. In order to know the simultaneity of events in different places, we must know the speed of signal transmission, but how to measure this speed? We must measure the spatial distance between the two places and the time required for signal transmission. The measurement of spatial distance is simple, but the trouble lies in the measurement time. We must assume that every place has an aligned clock, and the propagation time of the signal can be known from the readings of the two clocks. But how do we know that the clocks in different places are right? The answer is that another signal is needed. Can this signal set the clock right? If we follow the previous thinking, it needs a new signal, so it will retreat indefinitely, and the simultaneity of different places cannot be confirmed. But one thing is clear, simultaneity must be associated with a signal, otherwise it is meaningless to say that these two things happen at the same time.
Optical signal may be the most suitable signal for a clock, but the speed of light is not infinite, which leads to a novel conclusion that two things happen at the same time for a stationary observer but not for a moving observer. Let's imagine a high-speed train, its speed is close to the speed of light. When the train passed the platform, A stood on the platform, and two lightning flashes appeared in front of A's eyes, one at the front end of the train and the other at the back end, leaving traces at both ends of the train and the corresponding parts of the platform. Through measurement, the distance between A and both ends of the train is equal, and the conclusion is that A saw two lightning flashes at the same time. Therefore, for A, two received optical signals travel the same distance in the same time interval and reach his position at the same time. These two things must happen at the same time, and at the same time. But for B in the center of the train, the situation is different, because B moves with the high-speed train, so he will intercept the front-end signal that propagates to him first, and then receive the optical signal at the back end. For B, these two events are different at the same time. In other words, simultaneity is not absolute, but depends on the observer's motion state. This conclusion denies the framework of absolute time and absolute space based on Newtonian mechanics.
Relativity holds that the speed of light is constant in all inertial reference frames, and it is the maximum speed at which an object moves. Due to the relativistic effect, the length of the moving object will become shorter and the time of the moving object will expand. However, due to the problems encountered in daily life, the speed of motion is very low (compared with the speed of light) and the relativistic effect cannot be seen.
Einstein established relativistic mechanics on the basis of completely changing the concept of time and space, pointing out that the mass increases with the increase of speed, and when the speed approaches the speed of light, the mass tends to infinity. He also gave a famous mass-energy relation: e = MC 2, which played a guiding role in the later development of atomic energy.
The establishment of general relativity;
1905, after Einstein published his first article on special relativity (that is, electrodynamics of moving objects), it did not immediately arouse great repercussions. But Planck, the authority of German physics, noticed his article and thought that Einstein's work could be comparable to Copernicus's. It is precisely because of Planck's promotion that relativity quickly became a topic of research and discussion, and Einstein also attracted the attention of academic circles.
1907, Einstein listened to his friend's advice and submitted the famous paper, and applied for the position of supernumerary lecturer at Federal Institute of Technology, but the answer was that the paper was incomprehensible. Although Einstein is very famous in the German physics field, in Switzerland, he can't find a teaching post in a university, and many famous people began to complain about him. 1908, Einstein finally got the position of supernumerary lecturer and became an associate professor the following year. 19 12 years, Einstein became a professor, 19 13 years, at the invitation of Planck, he became the director of the newly established Institute of Physics of Emperor William and a professor at Berlin University.
At the same time, Einstein is considering expanding the accepted theory of relativity. For him, there are two problems that make 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 universal gravitation. Newton's theory of gravity is beyond distance, and the gravitational interaction between two objects is instantaneous, that is, at infinite speed, which conflicts with the view of field on which relativity is based and the limit of light speed. The second problem is the non-inertial system, and the special theory of relativity, like the previous physical laws, only applies to the inertial system. But in fact, it is difficult to find the real inertial system. Logically speaking, all natural laws should not be limited to inertial systems, and non-inertial systems must also be considered. It is difficult for special relativity to explain the so-called twin paradox. Paradoxically, there are two twins. My brother is traveling near the speed of light in a spaceship. According to the effect of relativity, the high-speed clock slows down. When my brother came back, he was very old, because the earth had gone through decades. According to the principle of relativity, the spacecraft moves at a high speed relative to the earth, and the earth also moves at a high speed relative to the spacecraft. Brother looks younger than brother, and brother should look younger. This question can't be answered at all In fact, special relativity only deals with uniform linear motion, and my brother has to go through a process of variable speed motion to come back, which relativity can't handle. While people are busy understanding the relative special relativity, Einstein is continuing to complete the general relativity.
1907, Einstein wrote a long article about the special theory of relativity, "On the Principle of Relativity and Its Conclusions". In this article, Einstein mentioned the principle of equivalence for the first time, and since then, Einstein's thoughts on the principle of equivalence have been developing continuously. Based on the natural law that the inertial mass is directly proportional to the gravitational mass, he proposed that the uniform gravitational field in an infinitely small volume can completely replace the frame of reference for accelerating motion. Einstein also put forward the view of closed box: no matter what method is used, the observer in closed box can't be sure whether he is still in the gravitational field or in the accelerating space without gravitational field. This is the most commonly used viewpoint to explain the equivalence principle, and the equality of inertial mass and gravitational mass is the natural inference of the equivalence principle.
1915438+01In June, Einstein submitted four papers to the Prussian Academy of Sciences. In these four papers, he put forward a new viewpoint, proved the precession of Mercury's perihelion, and gave the correct gravitational field equation. At this point, the basic problems of general relativity have been solved and general relativity was born. 19 16 years, Einstein finished his long paper "The Basis of General Relativity". In this article, Einstein first called the theory of relativity that once applied to the inertial system as special relativity, and called the principle that only the physical laws of the inertial system are the same as the principle of special relativity as special relativity, and further expressed the principle of general relativity: for any moving reference system, the physical laws must be established.
Einstein's general theory of relativity holds that space-time will be curved due to the existence of matter, and the gravitational field is actually a curved space-time. Einstein's theory that space is bent by the sun's gravity well explains the unexplained 43 seconds in the precession of Mercury's perihelion. The second prediction of general relativity is gravitational redshift, that is, the spectrum moves to the red end in a strong gravitational field, which was confirmed by astronomers in the 1920s. The third prediction of general relativity is that the gravitational field deflects light, and the gravitational field closest to the earth is the solar gravitational field. Einstein predicted that distant starlight would deflect 1.7 seconds if it passed through the surface of the sun. 19 19, encouraged by British astronomer Eddington, Britain sent two expeditions to observe the total solar eclipse in two places. After careful study, the final conclusion is that the starlight does deflect around the sun for 1.7 seconds. The Royal Society and the Royal Astronomical Society officially read out the observation report, confirming that the conclusion of general relativity is correct. At the meeting, Tang Musun, a famous physicist and chairman of the Royal Society, said: This is the most significant achievement in the theory of gravity since Newton's time? ,? Einstein's theory of relativity is one of the greatest achievements of human thought? . Einstein became a news figure. 19 16 years, he wrote a popular book about relativity, Introduction to Special and General Relativity. By 1922, it has been reprinted 40 times, translated into more than a dozen languages and widely circulated.
The significance of relativity:
Special relativity and general relativity have been established for a long time. It has stood the test of practice and history and is a recognized truth. Relativity has a great influence on the development of modern physics and modern human thought. Relativity logically unifies classical physics and makes it a perfect scientific system. On the basis of the principle of special relativity, special relativity unifies Newton's mechanics and Maxwell's electrodynamics, pointing out that both of them obey the principle of special relativity and are covariant to Lorentz transformation, while Newton's mechanics is only a good approximate law of low-speed motion of objects. On the basis of generalized covariation, general relativity establishes the relationship between local inertia length and universal reference coefficient through equivalence principle, obtains the generalized covariant forms of all physical laws, and establishes the generalized covariant gravity theory, and Newton's gravity theory is only its first-order approximation. This fundamentally solved the problem that physics was limited to inertial system in the past, and got a reasonable arrangement in logic. Relativity strictly examines the basic concepts of physics such as time, space, matter and motion, and gives the time-space view and material view of scientific system, thus making physics a perfect scientific system logically.
Special relativity gives the law of high-speed motion of objects, and puts forward that mass and energy are equivalent, and gives the relationship between mass and energy. These two achievements are not obvious to macroscopic objects moving at low speed, but they are extremely important in the study of microscopic particles. Because the speed of microscopic particles is generally relatively fast, and some of them are close to or even reach the speed of light, the physics of particles cannot be separated from relativity. The mass-energy relationship not only creates the necessary conditions for the establishment and development of quantum theory, but also provides the basis for the development and application of nuclear physics.
At that time, most physicists on earth, including Lorenz, the founder of relativistic transformation relation, found it difficult to accept these new concepts introduced by Einstein. Some people even say? At that time, only two and a half people in the world understood the theory of relativity? . The obstacle of the old way of thinking makes this new physical theory not familiar to physicists until a generation later. Even when the Swedish Academy of Royal Sciences awarded Einstein the Nobel Prize in Physics in 1922, it just said? Because of his contribution to theoretical physics, he discovered the law of photoelectric effect. ? Einstein's Nobel Prize in Physics was awarded, but Einstein's theory of relativity was not mentioned. (Note: Relativity didn't win the Nobel Prize. One of the important reasons is the lack of a large number of facts. )
photoeffect
1905, Einstein put forward the photon hypothesis and successfully explained the photoelectric effect, so he won the 192 1 year Nobel Prize in Physics.
When light irradiates a metal, the electrical properties of this substance will change. This photochromic phenomenon is collectively called photoelectric effect.
The photoelectric effect can be divided into photoelectron emission, photoconductive effect and photovoltaic effect. The former phenomenon occurs on the surface of an object, which is also called external photoelectric effect. The latter two phenomena occur inside the object, which is called internal photoelectric effect.
Hertz discovered the photoelectric effect in 1887, and Einstein was the first to successfully explain the photoelectric effect (the effect that a metal surface emits electrons under the action of light irradiation, and the emitted electrons are called photoelectrons). Only when the wavelength of light is less than a certain critical value can electrons be emitted, that is, the limit wavelength, and the corresponding frequency of light is called the limit frequency. The critical value depends on the metal material, and the energy of emitted electrons depends on the wavelength of light, which has nothing to do with the intensity of light and cannot be explained by the fluctuation of light. And the fluctuation of light is also contradictory, that is, the instantaneity of photoelectric effect. According to the fluctuation theory, if the incident light is weak and the irradiation time is long, the electrons in the metal can accumulate enough energy and fly out of the metal surface. But the fact is that as long as the frequency of light is higher than the limit frequency of metal, no matter the brightness of light, the generation of photons is almost instantaneous, no more than ten MINUS nine seconds. The correct explanation is that light must be composed of strictly defined energy units (i.e. photons or optical quanta) related to wavelength.
In the photoelectric effect, the emission direction of electrons is not completely directional, but most of them are emitted perpendicular to the metal surface, regardless of the irradiation direction. Light is electromagnetic wave, but light is an orthogonal electromagnetic field with high frequency oscillation, and its amplitude is very small, which will not affect the emission direction of electrons.
conservation of energy
E=mc？ , the law of material immortality, said the immortality of the material quality; The law of conservation of energy is about the conservation of energy of matter.
Although these two laws have been discovered one after another, people think that they are two unrelated laws, each of which explains different natural laws. Some people even think that the law of immortality of matter is a chemical law, and the law of conservation of energy is a physical law, belonging to different scientific categories.
Einstein thought that the mass of matter is a measure of inertia and energy is a measure of motion. Energy and mass are not isolated from each other, but are interrelated and inseparable. The change of the mass of the object will change the energy accordingly; And the change of the energy of the object will change the mass accordingly.
Einstein put forward the famous formula of mass and energy in special relativity: e = MC 2 (where e stands for energy, m stands for mass, c stands for the speed of light, and the approximate value is 3? 10 8m/s, indicating that mass reduction can create energy).
Einstein's formula of mass-energy relationship correctly explains various nuclear reactions: Take Helium 4(He4) as an example, its nucleus consists of two protons and two neutrons. In principle, the mass of helium 4 nucleus is equal to the sum of the masses of two protons and two neutrons. In fact, this arithmetic doesn't hold water. The mass of helium nucleus is 0.0302u (atomic mass unit) less than the sum of the mass of two protons and two neutrons! Why is this? Because when two deuterium [dao] nuclei (each deuterium contains 1 proton and 1 neutron) are polymerized into 1 helium 4 nuclei, a large amount of atomic energy is released. When generating 1 g helium 4 atom, it is about 2.7? Atomic energy 10 12 joules. Because of this, the mass of helium 4 nucleus decreases.
This example vividly shows that when two deuterons are polymerized into 1 helium 4 nucleus, it seems that the mass is not conserved, that is, the mass of helium 4 nucleus is not equal to the sum of the two deuterons. However, according to the formula of mass-energy relationship, the mass lost by helium-4 nucleus is exactly equal to the mass reduced by releasing atomic energy during the reaction.
Einstein expounded the essence of the law of immortality of matter and the law of conservation of energy from a newer height, and pointed out the close relationship between the two laws, which made human beings further understand nature.
cosmical constant
Einstein used the cosmological constant when he put forward the theory of relativity (in order to explain the existence of a static universe with non-zero density of matter, he introduced a term in the gravitational field equation that is proportional to the metric tensor, using symbols? Express delivery. This proportional constant is very small and can be ignored at the galactic scale. Only on the cosmic scale can it be meaningful, so it is called the cosmological constant. The so-called fixed value of antigravity) into his equation. He believes that there is an anti-gravity that can balance gravity and make the universe finite and static. When Hubble showed Einstein the astronomical observation results of the expanding universe, Einstein said: This is the biggest mistake I made in my life. ?
The universe is expanding. Hubble and others believe that anti-gravity does not exist, and the expansion speed is getting slower and slower due to the gravity between galaxies. There is a twisting force between galaxies, which makes the universe expand continuously. This is dark energy. 7 billion years ago, they? Overcome? Dark matter becomes the master of the universe. The latest research shows that dark matter and dark energy account for about 96% of the universe in mass composition (only real mass, no virtual matter). It seems that the universe will continue to accelerate its expansion until it collapses and dies. There are other arguments, which are controversial. Although the cosmological constant exists, the value of anti-gravity far exceeds gravity. Linde said humorously: I finally understand why he (Einstein) likes this theory so much that he is still studying the cosmological constant after many years. Cosmic constant is still one of the biggest problems in physics today. ?