First, let's look at the rules of Landau ranking. Landau ranking ranks scientists in the field of physics according to their qualifications. This ranking is divided into 0 to 5 grades, with 0 grade corresponding to the godfather of physics and Newton the only one; 0.5 is a superb physicist, and Einstein is here; 1 class corresponds to first-rate physicists, including Bohr, Heisenberg, Dirac, Schrodinger, Bose, Wigner and others. Landau ranked himself at level 2.5, but later he put forward the second-order phase transition theory and ranked himself at level 2. There are more people in the next 3~5 grades, including almost all Nobel Prize winners, and Yang Zhenning is also in the fifth grade.
Newton, Einstein, Schrodinger, Bose, Heisenberg, Bohr, Dirac, Wigner, these people are ahead of Yang Zhenning and have nothing to say, because they really created a new field, which Yang Zhenning really can't reach. So where should Yang Zhenning rank? In fact, Yang Zhenning's contribution to science is a bit like Tesla's. He made the final achievement on the basis of predecessors.
One thing to point out here is that when Landau ranked this place, Yang Ning Zhenning's achievement was not so great, so it was reasonable compared with that time. Now Yang Zhenning's ranking should be at 1 level, and the overall ranking of scientists is in the top 30. After all, many scientists in the west are still very powerful, which we have to admit.
Finally, talk about the scientific achievements of Landau and Yang Zhenning respectively.
Landau, a genius in physics
Landau was an outstanding physicist in the former Soviet Union. This field of physics is particularly gifted and clever. He has shown his genius since he was a teenager. He was able to study at the age of four, graduated from high school at the age of thirteen and entered the university at the age of fourteen. During his college years, he calculated the quantum mechanics of Heisenberg, Schrodinger, Sommerfeld and Dirac.
Landau devoted his life to the development of Soviet physics. On his 50th birthday, he received a gift carefully prepared for him by the Institute of Atomic Energy of the Soviet Union: a marble slab engraved with his ten important scientific achievements, which is the famous "Landau Ten Commandments" in physics.
These ten commandments specifically refer to:
Density matrix and statistical physics in quantum mechanics;
Free electron diamagnetism theory;
Study on second-order phase transition:
Magnetic domain theory of ferromagnetism and theoretical explanation of antiferromagnetism;
Mixed state theory of superconductors:
Probability theory of nucleus;
Quantum theory of superfluidity of helium Ⅱ:
Charge limitation theory of elementary particles;
Quantum theory of Fermi liquid:
CP invariance of weak interaction.
Yang Zhenning's achievements
1) phase transition theory
Statistical mechanics is one of the main research directions of Yang Zhenning. His characteristic in statistical mechanics is to strictly solve and analyze the general model rooted in physical reality, so as to grasp the essence and essence of the problem. From 65438 to 0952, Yang Zhenning and his collaborators published three important papers on phase transition. The climax of these papers is the unit circle theorem in the second paper, which points out that the zero point of the giant partition function of the lattice gas model attracting interaction lies on the unit circle on the complex plane.
2) Boson many-body problem
Out of his interest in liquid helium superfluid, Yang Zhenning published or completed a series of papers on thin boson multibody systems with his collaborators around 1957.
First, he published two papers with Huang and Luttinger, and applied the pseudopotential method to this field. After writing the article "Is parity conserved in weak interaction", while waiting for the experimental results, the correct ground state energy correction was obtained by double collision method, and then the same results as Huang and Huang were obtained by pseudo potential method.
The most surprising energy correction they got was the famous square root correction term, but it could not be verified by experiments at that time. However, with the development of cold atomic physics, this correction term has been confirmed by experiments.
3) Exact solution of boson in the repulsive potential of 1 dimensional δ function at finite temperature.
In 1969, Yang Zhenning and Yang Zhenping pushed the boson problem in the repulsive potential of 1 dimensional δ function to a finite temperature. This is the first time in history that a quantum statistical model of interaction is obtained at a finite temperature (T >). This model and results were later realized and verified by experiments in the cold atomic system.
4) Theoretical explanation of superconducting magnetic ionization.
196 1 year, through close communication with Fei Zhengqing experimental group, Yang Zhenning and byers theoretically explained the superconducting magnetic ionization discovered by the experimental group, proved that electron pairing can lead to observed phenomena, clarified the basic principle of electromagnetic field without introducing new principles, and corrected the mistakes of London reasoning. In this work, Yang Zhenning and byers applied gauge transformation technique to condensed matter system. Related physics and methods were later widely used in the study of superconductivity, superfluidity and quantum Hall effect.
5) Off-diagonal long program
1962, Yang Zhenning put forward the concept of "long-range order from two angles", thus describing the essence of superfluidity and superconductivity in a unified way, and deeply discussing the root of flux ionization. This is a key concept of contemporary condensed matter physics. From 1989 to 1990, Yang Zhenning found the eigenstate with off-diagonal long program in the Hubbard model closely related to HTS, and found its SO(4) symmetry with Zhang Shousheng.