In the modern quantum mechanical model, the quantum number describing the electron layer is called the principal quantum number.
Number) or quantum number n, the value of n is a positive integer 1, 2, 3, 4, 5, 6, 7, and the corresponding symbols are K, L, M, N, O, P, Q. For hydrogen atoms, N is certain, and the energy of its motion state is also certain. Generally speaking, the greater the n, the higher the energy of the electron shell.
From all the elements in the first to seventh periods, people found four energy levels, which were named S, P, D and F respectively. Theoretically, the fifth energy level will appear in the eighth cycle.
The internal contradictions and difficulties of everything are the internal driving force for the development of things. It is the contradictions and difficulties of the old quantum theory that push quantum physics to a higher stage and produce the theory of quantum mechanics. At present, it is generally believed that 1924 ~ 1930 is the period of creation and perfection of quantum mechanics. A brief introduction is as follows:
19 13 The first Suwei conference, which is recognized as the "International Physics Summit", was held. At this conference, quantum theory was considered as a theory of universal significance in the field of physics. So quantum physics has attracted the attention of almost all physicists, especially young physicists. After that, quantum physics developed rapidly along two relatively independent routes.
First, a large number of relatively young physicists followed Bohr's steady-state transition theory and Bohr's correspondence principle proposed by 19 16, and extended their application scope from hydrogen atoms to complex systems applicable to all atoms, which led to the establishment of quantum mechanics in the form of Heisenberg matrix mechanics and the discovery of 1925 electron spin.
The second is to develop along Einstein's ideological line of wave-particle duality. Directly lead to 1924 de Broglie (L.V.de
Broglie, 1892- 1987) proposed that electrons also have wave properties, and wave-particle duality is De Broglie's wave theory with the same properties as all microscopic objects. Please refer to Zhou Fazhe's previous blog post for details.
One, 24-year-old Heisenberg pioneered the matrix mechanics of quantum mechanics.
1July, 925, 24-year-old Werner Karl
Heisenberg 190 1 ~ 1976) The first paper on quantum mechanics, Reinterpretation of the Relationship between Kinematics and Dynamics by Quantum Theory, was immediately handed over to his teacher Born. At that time, Heisenberg himself was not confident in this paper, so he asked the teacher to read it and decide whether it was worth sending it out for publication.
Born was immediately attracted by this paper! At first glance, the most amazing step of this paper is to define the quantum theoretical transition amplitude of coordinate Q and momentum P in the mechanical formula. Although there are still many vague things in the paper, this one is a major scientific innovation!
So Born immediately sent Heisenberg's article to the German journal of physics for publication, but he was immersed in thinking about Heisenberg's qp and pq "symbolic product" algorithm all day and couldn't sleep for several nights in a row.
One morning, Born suddenly realized that Heisenberg's symbolic product method was just a matrix operation! Born studied matrices when he was a student, and he knew the operation of matrices. Heisenberg didn't learn matrix when he was a student, and he didn't understand matrix operation, so although the paper actually introduced matrix operation, it was not clear.
So Born immediately decided to transform Heisenberg's paper into a clear matrix form. To this end, he found Jordan to help him with his work. In September, Heisenberg's second paper on quantum mechanics, About Quantum Mechanics, was published.
Heisenberg was a visiting scholar in Bohr, Copenhagen. After learning this news, he was greatly encouraged, and he immediately made up lessons in The Matrix.
Born 10 Prepare1Visit the United States at the end of October. He felt that there were still many problems in the matrix form of "quantum mechanics" that needed to be further studied and improved and applied to practical problems, so he immediately recalled Heisenberg from Copenhagen and wrote another paper named after Born, Heisenberg and Jordan. At this point, the matrix quantum mechanics initiated by Heisenberg has developed into a complete set of "matrix mechanics".
Secondly, Bohr's Copenhagen School contributed to matrix mechanics.
Another important force that gave great support and help to the establishment and perfection of Heisenberg's quantum mechanics was Bohr and the scholars around him.
Heisenberg was originally a student of sommerfeld at Muny University. 1922, sommerfeld was going to be a visiting professor at the University of Wisconsin, and sent Heisenberg to Born, University of G? ttingen. 1September, 924, Heisenberg was sent to Bohr as a teaching assistant and served as a cooperative researcher for a period of time, which gave Heisenberg an opportunity to deeply understand Bohr's scientific and philosophical thoughts, and was later called "the source of Copenhagen spirit", and specially followed Clemens (H.A.Kramers, 1894-65438+).
Heisenberg's first paper on quantum mechanics was formed in Copenhagen for more than half a year, from ideas to methods. He also discussed the ideas and calculation results in the paper with his friends Pauli, R.L. Kronig and Clemens when he worked there, and got a lot of help from them.
The biggest support and help from Copenhagen is that Heisenberg's quantum mechanics was challenged by Schrodinger's wave mechanics after it came out, while the older generation of physicists showed a tendency to favor Schrodinger's wave mechanics and criticized Heisenberg's quantum mechanics more than appreciated it. At this time, Bohr stood out in a clear-cut manner, fully supported Heisenberg's quantum mechanics, demonstrated and solved problems for him, and constantly overcame the existing defects and deficiencies, and finally gained the recognition of the whole physics community.
Third, Dirac, an supernumerary member of Copenhagen School.
Dirac (1902— 1984) has also made important contributions to the supplement, development and perfection of Heisenberg's quantum mechanics.
192 1 year, dirac entered Cambridge university shortly after graduating from the department of electrical engineering of Bristol university in England. He loved mathematics since he was a child and was very talented in mathematics. At that time, it was the golden age of physics development, and the purpose of entering Cambridge University as a graduate student was to further develop my physics.
June 65438+July 0925 Heisenberg was invited to visit Cambridge University. On July 28th, Heisenberg gave a speech at Cambridge University, introducing his first paper on the creation of quantum mechanics. At that time, Dirac's tutor, W.A.Fowler, was very interested in Heisenberg's work and asked Heisenberg for the preprint of the paper. Did Chandler get it and give it to Dirac, let him study it first and then make comments. Dirac didn't care too much at first, but he soon saw the significance of Heisenberg's paper. Dirac immediately turned his attention to Heisenberg's research on quantum mechanics.
1winter of 925 and1spring of 926, Dirac, who was under 24 years old, published many papers successively, such as Basic Equation of Quantum Mechanics and On Quantum Mechanics, and expounded Heisenberg's quantum mechanics from the perspective of the connection and transition between quantum mechanics and classical mechanics. This greatly shortens the distance for the older generation of physicists who are familiar with the classical mechanics theory to accept the new quantum mechanics theory.
1926 In the spring, after Schrodinger's paper on wave mechanics was published, the physics circle was puzzled about whether Heisenberg's quantum mechanics and Schrodinger's wave mechanics were interlinked. Although Schrodinger proved that the conclusions of these two theories are consistent in June of that year, this proof is special and difficult to understand, and people's confusion has not been completely eliminated.
On the basis of the work of Heisenberg and Schrodinger, Dirac published two articles in succession from the autumn of 1926 to the beginning of 1927, which is now called the "representation transformation theory" of quantum mechanics, bringing the quantum mechanics independently founded by Heisenberg and Schrodinger into a highly unified and harmonious new theoretical framework of quantum mechanics. This theoretical framework reflects the transformation relationship between differential equation and matrix, which is widely used in mathematics, and embodies the idea of canonical transformation in Hamiltonian theory of classical mechanics in physics, and the probability explanation of continuous wave function has been further promoted.
Dirac's work has played an important role in perfecting the current theory of quantum mechanics. Therefore, when Heisenberg's quantum mechanics was finally recognized as the orthodox quantum mechanics theory by the physics circle, people regarded Dirac as the main member of Copenhagen School, and thought that his contribution to the development of quantum physics could be comparable to Bohr, Heisenberg and Born.