Silently reflecting autumn water 丨 The 120th anniversary of the founder of the quantum mechanics Dirac

Written article | Cao Zexian (Institute of Physics of the Chinese Academy of Sciences)

I have an equation. Do you have one too?

—— Paul Adrien Maurice Dirac [1]

Abstract Dirac is a monument in the history of physics. It has profound thoughts and light styles, showing a typical British mathematical physics

The concept expands the world of micro particles. Dirac's work style is hailed by Mr. Yang Zhenning as "the autumn water article is not dyed". Its explanation of quantum mechanics, quantum field theory, general theory of relativity, rotation theory, and electromagnetics are all classic works, which are simple and easy to understand. Especially admirable is Dirac's pure mind. He always pays attention to the social content of physics itself rather than physical (). Dirac is taciturn. Dirac (1 Dirac = 1/How), who is a sociological unit, may be the most interesting contribution left by Dirac to human society.

01

Attractive

Quantum mechanics is the greatest ideological achievement of human beings in the twentieth century. Roughly speaking, the approximate framework of quantum mechanics is used by acting quantum H (optical energy quantum is e = HV), regular quantum condition (x, p) = iћ, and the amount of momentum that comes from this moment indicates that the amount of kinetic quantity indicates represents

Linear space theory, operator generation, spectrum theory, principles of division, complexity, complexity, complex function, group theory, rotation theory, etc., can talk about primary quantum mechanics. The establishment of quantum mechanics has benefited from the brainstorms of a batch of physicists in the early 20th century. In the founders of quantum mechanics, Dirac is still the one who is talented and excellent.

02

Dirac

Paul Adrien Maurice Diraca (1902.08.08-1984.10.20) was born in a ordinary family in Bristol, England. Dirac's mother was British, and his father was from Switzerland. He returned to Britain in 1919. I remember that I had read that Dirac Zu was somewhere in French Champagne. AU is a grassland in German DONAU (Danube), Aarau (Einstein's town in Switzerland). The place name, it is said that the village where Dirac Zu was on the village included the famous COGNAC (Cognac Bailan Land) and Cadillac (Cadillac), and of course Dirac Village. Dirac's father taught French in middle school and asked his children to speak French at home. Because French grammar is tedious, children in foreign countries, or children are in foreign countries, are difficult to say French perfectly. Dirac's father was too severe to treat the child, and the child's French was not correct to be punished. Because he was afraid that French would be beaten, Dirac was avoiding speaking as much as possible when he was a child, which made him a dumb habit (Figure 1). Some literatures said that Dirac's colleagues in Cambridge joked that Dirac was used as a metering unit to express the content of the person's talk, 1 Dirac = 1 word/hour (1 dirac = 1 word per hour). The author said boldly that the silence may help enter the state of deep thinking, which is a good thing. Zi said: "The gentleman wants to speak and be sensitive to his words." This is reasonable.

Figure 1. Dirac at the age of five

Dirac graduated from the University of Bristol to study electrical engineering in 1921. Due to the economic downturn after the First World War, Dirac failed to find a job of an engineer after graduation, so he continued to study mathematics at the University of Bristol — the author thought it was a key factor in the status of Dirac in the history of science. In 1923, Dirac received a scholarship from the University of Cambridge and entered Cambridge. From Ralph Howard Fowler, he obtained a doctorate degree in 1926. The topic of the paper "Quantum Mechanics" was simple (Figure 2). I guess this should be the shortest doctoral dissertation in history. Dirac's doctoral dissertation is 72 pages, which not only contains the quantum-to-ease of general computing, but also the content of quantum statistics, which was later named Fermi Dirac statistics. Dirac's doctoral dissertation has caused strong response in the European continent, including caught Einstein's attention. Einstein talked about Dirac's paper, "I have true with dirac. This Balancing on the Dizzying Path Between Genius and Madness is awful. The balance is too cool). ". Mathematics is not a very strong person to read Dirac's paper and it is easy to feel.

Figure 2. Homepage of Dr. Dirac Thesis

In 1933, Dirac won the Nobel Prize in Physics for "FOR The Discovery of New Productive Forms of Atomic Theory" because of the "discovery of the fruit theory". A very interesting anecdotes in the history of physics. In 1933, Xue Dingzhang, Dirac and Heisenburg, who were shared with the Nobel Prize that year, took a photo when they met at the railway station (Figure 3). In the photo, there are three ladies, one is Xue Dingzheng's wife, and the other two are the mother of Heisenburg and the mother of Dirac. A Lecture Professor and Nobel Prize winner of a Cambridge University did not even have a girlfriend, and they did worry their friends. Enthusiasm Eugene Wigner (1902-1995) introduced her sister to Dirac. Dirac married in 1937 and stayed with his wife for a lifetime. Figure 3. In 1933, Dirac, Heisenburg and Xue Dingzheng took a photo before the prize. From left: Hassonburg Mom, Xue Dingzhang's wife, Dirac Mom, Dirac, Haisenburg, Xue Dingzheng

From 1932 to 1969, Dirac was a Professor of Lucas at the University of Cambridge, which was the position that Newton had occupied. In 1970, Dirac settled in Florida, USA, where the University of Miami and Florida were lectured and studied. Dirac died in Tallahassee in Florida in 1984 and was buried there. Dirac's cemetery is worthy of future generations

A little bit of Dirac equation in the form of Dirac, which indicates that it is (3,1), is shown in Figure 5. To commemorate Dirac, later generations set up a lot of awards named Dilak, such as the Dirac Award set up by the British Institute of Physics.

Figure 4. Dirac's tombstone, engraved with Dirac equations

Figure 5. The standard form of Dirak equations written on the electronic whiteboard

03

Unique research method

Dirac's contribution to quantum mechanics, including quantum statistics, has many aspects, which cannot be detailed here. Two cases of transferring to the author's personal understanding. 1925年9月，导师把海森堡1925年7月29日提交的一篇论文(Heisenberg, Über quantentheoretische Umdeutung kinematischer und mechanischer Beziehungen (论运动学与力学关系的量子理论诠释), Zeitschrift für Physik, 33, 879-893, 1925. This article was handed over to Dirac's hands to study it in the first part of Bolin, Hyenburg, and about the matrix mechanical trilogy. In this article in Heisenburg, there is a relationship with the relationship between the ease (x, p) = xp-px = iћ. Di

For the specific details of the construction process, Dirac described in detail in Chapter 11 of the Book of Quantum Mechanics. The wave function in the Dirac equation is quarterly. In order to interpret Dirac equations and its understanding, Dirac proposed the concept of Positive Electron (Positron) in 1931. In 1932, Zheng Electronics was observed (Figure 6). The concept of positive electronics later expanded the concept of anti -particle and anti -material. The author boldly imagine that Dirac's story should be included in our teenager's reading book, so that our teenagers can understand that you can have a consciousness.

Figure 6. In the autumn of 1932, the electrons observed in the authenticity of the cosmic ray impact of the universe-positive electron pair event

就狄拉克创立相对论量子力学方程的工作，杨振宁先生说他曾长时间考虑也找不到恰当的评价表达，直到他读到了高适在《答侯少府》中的诗句：“性灵出万象， "I am very happy, I feel that I use these two poems to describe the Dirac equation and anti -particle theory. Especially vivid. "

04

Unique way of expressing

Silent Dirac is an outstanding and unique physics representative. Although the point-like distribution function used Einstein in the early 20th century to apply it to statistical physics, it was named the Dirac function, or the Dirac Δ-function.

Figure 7. The ice slippery of the eaves of the Forbidden City, the proper Dirac Combings

Of course, the introduction of two symbolic systems is not enough to support a person's physical giant status. Dirac is also a propagner and expressionman of physics (Figure 8), and many of them are his personal creation. The list of physics works left by Dirac to us is as follows:

1. The Principles of Quantum Mechanics (Principles of Quantum Mechanics), 1930;

2. LeCTURES on Quantum Mechanics

3. LeCTURES on Quantum Field Theory

5. General Theory of Relativity, 1975;

6. Directions of Physics, 1978;

Every article here is a classic. The two books I read carefully are "Principles of Quantum Mechanics" (Figure 9) and "Figure 10). Maybe because Dirac's understanding of physics is too transparent, a major feature of his works is clear thinking. Mr. Yang Zhenning said that Dirac's article was "the autumn water article is not stained with dust." The author thought it was described rather than praise. The author first read Dirac's "Principles of Quantum Mechanics" in the late 1980s, and was very unaccustomed to its style. After a long time, I understand that Dirac's "Principles of Quantum Mechanics" is not a textbook. He is the process of quantum mechanics as a founder of quantum mechanics. There is always a story or legend that has always been said.

From the perspective of pursuing the real learning process, "The Principles of Quantum Mechanics" can understand the significance of this book for the education of physicists. I think that one of the important significance of this book is to remind you that you can also put yourself in the position of future learning creators to learn and learn. The first printing of the Book of Quantum Mechanics was in May 1930, when Dr. Dirac was less than 28 years old.

Figure 8. Professor Dirac

Figure 9. Dirac 1930 "Principles of Quantum Mechanics"

Figure 10. Dirac printed by the author in 1975 "The theory of relativity in the broad sense"

"The Theory of relativity" was written in the United States in 1975. At that time, he was already the Thai Dou in the physics community. For all theoretical knowledge, he should be said to be pure. The short 69 pages of "The theory of relativity", but it is indeed what the general theory of relativity should be said from the vector of the bending space parallel movement, the regularity of the tensor, and the representation of the Einstan field equation, and why the gravitational wave spin is 2, all of which are all, all of which Speak clear.

05

Excessive words

Dirac is a physicist who can be called Mathemtatic Wizard. He adheres to the British mathematics traditions inherited from Newton, Hamilton, Creford, and Jerevin. The idea of ​​breeding is expressed in a clear and sometimes new mathematics, and finally brings new physics. Such a physical research style of the 20th century is found in the achievements of Einstein, Dirac, and Mr. Yang Zhenning. This method of research has strong individualism. As a thinker, a lonely thinker, and a silent thinker, the Diracs have a unique personality charm. Compared with Lone Ranger such as Einstein, Dirac, and Mr. Yang Zhenning, it is a little inferior to school leaders such as Sofei, Boan, and Langdo. As far as the thought is concerned, the school may not be decent.

Thinking of Laplas's sentence, "Read Euler, read Euler, he is the mentor of all of us!" In this era when this technology surpasses mythology, quantum mechanics should become the standard of the educated knowledge. On the 120th anniversary of Dirac's birthday, let us also read Dirac. While appreciating the beauty of natural rationality, we also learned the consciousness of building a knowledge creator.

references

1. Helge Kragh, Dirac: A scientific biography, Cambridge University Press (1990).

2. Graham Farmelo, The Strangest Man: The Hidden Life of Paul Dirac, mystic of the atom, Basic Books (2009).

3. Abraham Pais, Paul Dirac: The Man and His Work, Cambridge University Press (1998).

4. Behram N. KURSUNOGLU, EUGENE P. Wigner (ED.), Reminiscencese About A Great Physicist: Paul Adrien Maurice Dirac, Cambridge University Press (1987).

5. Helge Kragh, Varying Gravity, Dirac's Legacy in COSMOGY and Geophysics, Birkhäuser (2016).

Annotation

[1] I have a equation.Do you have it too?Seeing Anthony Zee, Quantum Field Theory in a Nutshell, Princeton University Press (2010). [2] The German Hermann Grassmann (1809-1877) prepared such an opposite number.

[3] Symmetrical, he said that Bose-Einstein statistics were based on Bose statistics.Paralying has always regarded Bosis-Einstein statistics with Fermi Dirac statistics as symmetrical and equivalent, and the author is afraid to agree.Rongshi has the opportunity to discuss special articles

Produced: Popular Science China

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