The classic of physics , The Maxwell Equation " , was expanded more than 100 years later? Recently, a "conference of important original achievements" held by the Beijing Institute of Nanoenergy and Systems of the Chinese Academy of Sciences caused controversy. Around a paper published last year by Wang Zhonglin, director of the institute and foreign academician of the Chinese Academy of Sciences, several scholars in the physics community pointed out three questions, and the Intellectuals sorted out the details of the controversy and sorted out the release. In addition, "Intellectuals" also received an exclusive written response from Wang Zhonglin, and the public account published two articles questioning and responding on the same day, giving science a space for contention. The more the truth is argued, the clearer it becomes.
Academicians cross-border publication of major achievements
In middle school, we all did this experiment: let a magnet pass through the coil, and the coil will produce an electric current. This is the most basic electromagnetics, which studies the interaction between electricity and magnetism. If electromagnetism is a edifice, maxwell's equations are its foundation. This system of equations, born in the 1860s, consists of four equations that describe the laws of electrostatic, magnetic, electromagnetic, and magnetoelectric.
Recently, a study led by Wang Zhonglin, a foreign academician of the Chinese Academy of Sciences, has attracted domestic media attention. This study expands the application scope of Maxwell's equations, and related reports[2] say that it "laid the theoretical foundation for the electrodynamics of moving dielectrics", called "an important contribution made by Chinese scientific research institutions to the innovation of classical physics basic theory", and has "huge potential application scenarios".
At the press conference, many media such as China Central Radio and Television Corporation, People's Daily, China Daily, China Science Daily, Beijing Daily, and Beijing Radio and Television Station were invited to make on-site reports
The study was published in October 2021 in the international academic journal Materials Today. On the afternoon of January 13, 2022, the Beijing Institute of Nanoenergy and Systems of the Chinese Academy of Sciences held a press conference, inviting a number of government units and official media to attend, saying that Wang Zhonglin had successfully expanded Maxwell's equations after several years of research and experimental verification. Wang Zhonglin is the director and chief scientist of the Beijing Institute of Nanoenergy and Systems, Chinese Academy of Sciences.
However, as soon as the news was released, it was questioned by many parties.
The social platform knows the previous article about "How to evaluate Academician Wang Zhonglin's expansion of Maxwell's equations?" How valuable is it to the theory of physics? There were many skeptical voices under the topic, and one of the most praised answers clearly concluded that the expanded results were clearly wrong.
In response to the controversy of the paper, the digital physics professionals contacted by the Intellectuals generally gave two evaluations: some people pointed out that the application of Maxwell's equations in the moving medium has long been determined by the academic community, and the results are not the "important results" of the foundational formula; others point out that the derivations in the paper are wrong and the conclusions drawn are unreliable.
In addition, the controversy was sparked by Materials Today, which published the paper, which is reported to be an academic journal in the field of materials science, not a journal in the field of physics.
Points of controversy in the academic community
Does Maxwell's equations need to be "extended"?
The first sentence of the abstract of Wang Zhonglin's paper states, "Traditional Maxwell's equations apply to media with fixed boundaries and volumes. However, for cases involving moving media and time-dependent configurations, the equation must be extended. The subsequent derivations and conclusions of the paper have been developed from this point.
However, several experts in the fields of physics and materials science point out that this argument is inherently problematic.
"The electrodynamics of moving media is the problem that Einstein wanted to solve 117 years ago, and thinking and researching on this problem led to one of the greatest discoveries in the history of physics, the birth of special relativity," said Dai Xi, chair professor of the Department of Physics at the Hong Kong University of Science and Technology. ”
Since then, scientists in the field of physics have also studied the application of electrodynamics of moving media in various systems, such as in 1976, the American physicists M. Lex and D.F. Nelson published a paper Maxwell equations in material form [5], carefully discussing Maxwell's equations in the problem of dielectric deformation. Theoretically, no matter what medium you are in, as long as you establish the constitutive relationship describing these media (Note: the constitutive relationship refers to the relationship between the physical quantities such as polarization and magnetization generated in the medium in electromagnetism and the strength of the electric and magnetic fields), and substitute it into Maxwell's equations, you can get the correct results, and there is no need to "expand" the equation system.
Dai Xi said that the flat motion discussed in Wang Zhonglin's paper is only a special case of the discussion in the above paper. Specifically, the translation of the rigid body is to keep the shape of the object unchanged, not deformed, not rotated, and moving straight.
In addition, in the 1984 textbook Continuous Dielectric Dynamics, which physics undergraduates are exposed to, there is a subsection devoted to this issue. "The applicability of equations to moving bodies is evident," writes a textbook written by the soviet physicist Lev Landau.
In fact, "a good college or graduate student, as long as he has read Landau's 'continuous dielectric electrodynamics', will not regard this thing as a great contribution, but only make some approximations to the generalization of Einstein's 'electrodynamics of moving body' medium." Sun Changpu, an academician and theoretical physicist at the Faculty of Mathematics and Physics of the Chinese Academy of Sciences, said.
Liu Wandong, Professor of the University of Science and Technology of China and Head of the Department of Modern Physics:
Looking at his (Wang Zhonglin)'s equation, it only divides the electric displacement vector into two parts, and the time partial differentiation becomes a full micro-quotient, which is just a natural result of putting the reference frame on the moving fluid element, so there is no theoretical contribution. This equation is the Maxwell medium equation in the moving medium reference frame, and there is no novelty.
Of course, refining the polarization model in the electrical displacement and considering the non-polarized part is more innovative for engineering applications, but that's about it.
Wang Zhonglin said his achievement was to expand Maxwell's equations. This expansion is natural, not innovative, much less innovative in the field of theoretical physics.
Dai Xi, Chair Professor, Department of Physics, The Hong Kong University of Science and Technology:
Wang Zhonglin's article wants to solve the problem, the electrodynamics of the moving medium, is the problem that Einstein wanted to solve 117 years ago, and the thinking and research on this problem led to one of the greatest discoveries in the history of physics, the birth of special relativity. Teacher Wang Zhonglin is worthy of being a "world-class scientist" with a high starting point, but this problem has been completely solved by Einstein, and it does not need to be solved in theory, but when it is applied to various special material systems, it is indeed necessary to solve some problems in engineering calculation.
The electrodynamics of moving media have long been written into textbooks, such as in Landau and Lifshitz's "Continuum Electrodynamics" there is a special chapter on this issue. Later, in the 1970s and 1980s, with the rapid development of various technical fields such as optics, nano, and microwave, many new problems were raised for the application of motion dielectric electrodynamics in various systems, and the development of this research direction was also promoted. On this point, Wang Wenyu, a teacher at Beijing University of Technology, wrote a very good introduction article in Physics and Engineering in 2018, "Lorentz Covariate Electromagnetic Theory of Moving Medium", which is easy to find on WeChat.
Teacher Wang, who has achieved great success in the field of nanoscience, became interested in this problem, which was a good thing, but unfortunately he did it wrong. His problem is that he wants to make non-relativistic approximations of electrodynamics in a medium, which requires great care, because in this problem there is the motion of matter in the medium and the motion of the electromagnetic field, and the laws of motion of matter (such as the electrons and ions that make up the medium) have non-relativistic limits at low speeds, while the laws of motion of the electromagnetic field are always relativistic and must satisfy the Lorentz transform instead of the Galileo transform. Yesterday, I also read Wang Wenyu's article to thoroughly understand this. Teacher Wang Zhonglin's "Extended Maxwell Equations" is precisely obtained by making Galilean transformations of the real Maxwell equations, destroying the most basic principle of relativity, which cannot be correct.
The road of science is arduous, as long as people are not gods will make mistakes, this is nothing, what really bothers me is that no one can remind him of the Institute of NanoEnergy of the Chinese Academy of Sciences? Before such a big publicity was promoted to the public media, why didn't the Academy of Sciences consult the relevant units in the academy, such as the Institute of Theoretical Physics or the experts of the Institute of Physics? Without an effective error correction mechanism, how to ensure that the scientific research funds invested by the state every year are put into good use? These questions deserve the deep consideration of the management of the Academy of Sciences.