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The feast is over: Yang's view of high-energy physics and the implications for China

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Intellectuals

The Intellectual

The feast is over: Yang's view of high-energy physics and the implications for China

Yang Chen-ning, 100 Years of Style | Drawing: Wang Ruonan

By | Huang Qingqiao (Professor, Institute of History and Culture of Science, Shanghai Jiao Tong University)

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Since the 20th century, along with the breakthrough development of mankind's exploration of the internal structure of matter, especially the successful application of atomic bomb technology in World War II, the development of high-energy physics, which is the foundation of basic science, has received great attention.

However, since the 1960s, expensive, purely fundamental research in high-energy physics began to be questioned, and of particular concern was the fact that many prominent physicists who were themselves engaged in high-energy physics research also expressed concern about the development of high-energy physics. For example, Mr. Chen Ning Yang, a theoretical physicist and Nobel laureate in physics, has a unique perspective on the development of high-energy physics. His unique views on high-energy physics have inevitably spread widely in China and have had a tremendous and far-reaching impact on the development of science in his country.

The feast is over: Yang's view of high-energy physics and the implications for China

Figure 1 Mr. Chen Ning Yang | Source: casad.cas.cn

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Sprinkling sand on top of a pile of sand.

The importance of high-energy physics

Since the second half of the 20th century, Yang has published an impressive number of pessimistic views on the development of high-energy physics. This has also created a false impression that he seems to ignore the tremendous achievements and far-reaching impact of physics as a whole in the 20th century. In fact, this is a misconception.

In April 1961, during the centennial celebration of the Massachusetts Institute of Technology (MIT), a symposium entitled "The Future of Physics" was held. Yang gave a speech at this symposium, and while the overall content of his speech showed that he was worried and pessimistic about the future of physics, in the first half of his speech he clearly praised the development of physics in the first half of the 20th century.

According to Yang, the achievements of physics in the 20th century are amazing by all standards.

At the beginning of the 20th century, the atomic face of matter was just emerging as a new subject of study, and today we have progressed a million times in the fineness of its scope: from atomic size to sub-nuclear size. The progress in terms of energy is even more impressive: from a few electron volts to billions of electron volts. The capabilities and sophistication of experimental techniques have also advanced as physicists have explored deeper. It is difficult to describe the significant impact that advances in physics have had on other disciplines - chemistry, astronomy, and even biology. The impact of developments in physics on technology, on human affairs, has been so prominent in the postwar period that there is no need for further emphasis here.

However, in Yang's view, the glory of 20th century physics was not based on these influences, nor were they what physicists valued most, nor was even the deepening and expanding scope of physical experiments a major aspect of physicists' satisfaction and pride. What physicists are most concerned with is the possibility of forming concepts from which, in Einstein's words, a 'complete and usable system of theoretical physics' can be constructed," he says. Such a system embodies the universal fundamental law that 'with this system, the universe can be constructed in a purely deductive way.'"

Obviously, as a theoretical physicist, Yang attaches special importance to the breakthrough of physical concepts, physical concepts and the construction of theoretical systems with universal applicability. According to Yang, in the field of physics, there are not only a large number of important discoveries that broaden our understanding of the physical world, but also revolutionary changes in proven physical concepts: special relativity, general relativity and quantum theory. "These three conceptual revolutions have resulted in a profound, complete, and unified system of theoretical physics that has acquired the remarkable legacy of the period just past."

In 2002, in his presentation at the International Conference on Theoretical Physics TH-2002 in Paris, Yang again spoke of the breakthroughs in fundamental concepts and their significance in 20th century physics: "It is difficult not to be impressed by the tremendous development of physics in the 20th century in terms of the decisive role it has played in human history. It is difficult not to be impressed by the decisive role that the tremendous developments in physics in the 20th century have played in human history. The real brilliance of 20th century physics lies in the deeper understanding of some important fundamental concepts that originated at the beginning of human civilization - space, time, motion, energy, and force. There has been a profound change in our understanding of all of these fundamental concepts, and what this change has brought us is a more beautiful, more subtle, more precise, and at the same time more unified description of nature."

Since the reform and opening up, Yang has strongly advised the Chinese government to develop applied science and advised Chinese students not to blindly choose his field of theoretical physics, especially high-energy physics, and strongly opposed the construction of high-energy gas pedals in China. This seems to give the impression that Yang despises or even denies the value of theoretical physics, especially high-energy physics. This is not the case.

In fact, as early as June 1972, when he returned to China for the second time, he spoke profoundly about the important academic value of high-energy physics in a symposium. in June 1972, Yang returned to China for the second time and had extensive exchanges with the Chinese scientific community, with 10 academic presentations or symposia. Among them, the symposium on June 28 was centered on high-energy physics. At the beginning of the symposium, he talked about the influence of high-energy physics in the United States and Europe in two aspects: First, in terms of technology, there was some influence, but it could not be said to be great. For example, the strong focus approach developed in 1952 has applications in industry, and various detectors have been used in industry with the Van de Graaff gas pedal - now considered low energy, of course - in industry, medicine, and so on.

"This is just one part of the impact of high-energy physics on society that is readily visible. There's the other side that's not readily visible all at once, which is the boost to physics as a whole, high-energy physics is the cutting edge of physics, and its development, to use an analogy, is like spreading sand on top of a pile of sand, and it improves from the base to the top, and the impact is great." "In the long run, there is no question that high-energy physics is something that must be developed." It is thus clear that Yang has a clear and profound insight into the importance and significance of developing high-energy physics, and as an "insider", there is no doubt that he gives full recognition and high praise to the profession he is engaged in.

Even the giant high-energy gas pedal, which he later strongly opposed, was highly praised by Yang, who celebrated the 20th anniversary of the AGS (alternating gradient cyclotron) at Brookhaven National Laboratory in the United States on May 22, 1980. In his speech after the symposium banquet, Yang gave a profound account of the contribution of the giant gas pedal to the development of physics as a whole from the perspective of a theoretical physicist: "In fact, it is no exaggeration to say that the history of our research field in the last 20 years has been largely the history of AGS, as the symposium this afternoon vividly demonstrated. A theoretical physicist is not quite so intertwined with gas pedals ...... Nevertheless, a theoretical physicist lives equally in the environment provided by the general trends in the field, and this environment is of course significantly influenced by the results that these big machines bring."

Looking ahead to the future of the large gas pedal, Yang said, "As we celebrate the 20th anniversary of this large gas pedal, it is natural to ask questions about the trends in high-energy physics in the next 20 years. I personally believe that there will undoubtedly be greater mysteries revealed and more great discoveries made in the future. Physics is constantly creating new wonders." It is thus clear that Yang is not a blanket denier of large gas pedals; he has a very deep understanding of their role.

Figure 2 U.S. Alternating Gradient Cyclotron | Image source: archive.org

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The feast is over.

A pessimistic view of high-energy physics

Yang not only explained the importance of high-energy physics, but as an "insider", he was also able to jump out of the "circle" of interests and express his pessimistic views and predictions on the future of high-energy physics. It should be emphasized that Yang's pessimistic view of high-energy physics is not meant to oppose the development of high-energy physics, but is a warning about the future of high-energy physics and its development path.

At the symposium "The Future of Physics" held at MIT in April 1961, Yang, after acknowledging the great achievements of high-energy physics, clearly expressed his pessimistic prediction about the development of high-energy physics. He said, "It is also difficult to predict by speculation what revolutionary changes will occur in the conceptual aspects of physics. But because of the tendency to believe in a 'fundamental theory of the future' without limit, I would like to make some pessimistic comments. It is perhaps not entirely inappropriate to insert some discordant melodies into this 100th anniversary celebration, where the whole atmosphere is filled with pride in past achievements and a broad outlook on future prospects."

Why did Yang "express some pessimistic opinions"? In his view, "the structure of the deeper and more complete theoretical system we envision must contain at least one more level of penetration. In this respect, physicists face the disadvantage that the ultimate judgment of theoretical physics is in reality. Unlike mathematicians and artists, physicists cannot create new concepts and construct new theories based solely on their free imagination."

However, "due to the complexity and indirect nature of the experiments, situations arise where people do not recognize the selective nature of the experiments they perform. Choices are based on concepts which may be inappropriate". A deeper reason lies in the contradiction between the finiteness of the human intellect and the infinity of nature. "The idea of believing that the depth of natural phenomena is finite is illogical, and the belief that the power of the human intellect is infinite is also incorrect. It is an important and necessary fact to consider that the physical and social limitations of each individual's creativity may be more serious than the limitations of nature".

In 2015, Yang authored an article recalling the 1961 meeting mentioned above. In the article, he posed the question: what have we learned in the more than 50 years since the 1961 meeting? He then answered, "A lot." "Through a deep collaboration between theoretical and experimental physicists, the following theories were proposed one by one and then experimentally verified one by one: a special symmetry-breaking model; weak electric theory; reformable non-abelian canonical fields; asymptotic freedom and QCD. and the final dramatic development was the discovery of the Higgs particle in 2012. So we have today a usable standard model, a SU(3)´SU(2) ´U(1) gauge theory. over 50 years we have succeeded in developing a deep layer of ideas, a new layer built on all previous layers of ideas and many tremendously new experiments."

Clearly, Yang was fully acknowledging the great strides made in physics in the half century since his pessimistic prediction in 1961. But then he turned to the question: "Are there deeper conceptions of physics that need to be discovered? I think there are, and there are many more layers. When will we reach the next layer? I think it will be a long time in the future, if ever." "Why are you so pessimistic?" "I'm not pessimistic, I'm just pragmatic." This shows that Yang is clinging to his pessimistic view of high-energy physics.

In 1980, physicist Marshak organized an international conference in the United States to discuss the future development of high-energy physics. Yang recalled that he was not among the speakers, but the moderator found him in the audience and invited him to speak on an ad hoc basis. Yang agreed to speak and made only one statement, but it was astonishing. He said, "The most important discovery in high-energy physics in the next 10 years was: The party is over. This is the origin of the later very famous "The party is over" in high-energy physics.

In 2000, Yang was working at the Chinese University of Hong Kong, and the famous Chinese-American physicist Huang Kesun was a visiting scholar at the Chinese University of Hong Kong. The two had a conversation when Yang, still holding his own views, told Kesun Huang, "Particle physics has come a long way in the past century, especially in these last 50 years, but its exclusive dominance of the leading position in physics is now coming to an end." In 2017, Yang included his conversation with Kesun Huang in The Morning Glory Collection, with the accompanying note.

I still believe today that in 1980 my phrase "The party is over" was correct.

1. All discoveries and developments in high-energy physics after 1980 and up to today have their theoretical basis originated before 1980 (e.g., the discovery of the Higgs particle in 2012 is certainly a major event in high-energy physics, but it was predicted before 1980).

2. Why were there no important developments in theoretical physics after 1980?

Almost all of the important theoretical developments in history originated in experiments: mechanics, thermodynamics, electromagnetism, quantum mechanics, etc. The 30 years of theoretical high-energy physics before 1980 were no exception: those 30 years of "strange particle" discoveries, since the "table top " experiments began, giving rise to high-energy physics, to an era of interaction between experiment and theory, and to an exciting "feast".

But around 1980, this feast could no longer continue: the experimental set-up had become so large (by the 21st century the experimental teams were bigger to thousands of people), the high-energy physics experiments became big plans and big budgets, the spirit and feeling of table top experiments exploring the mysteries of nature were lost, and high-energy theoretical physics thus lost the inspiration brought by the experimental results. The feast is over!

It follows that the key to Yang's insistence that "the feast is over" is that "the feast can no longer continue. This brings us to the question of Yang's attitude and views on high-energy gas pedals. It should be said that, in contrast to his pessimistic predictions about high-energy physics, Yang has the same reservations and even opposition to the construction of large high-energy gas pedals, as he is known, and has continued to publicly and vehemently oppose the construction of large high-energy gas pedals in China for decades.

Yang's reservations about large high-energy gas pedals are closely related to his physical thinking as a theoretical physicist. In his view, "the problem facing high-energy physics today is one of conceptual breakthrough rather than accuracy." "The key concept has to come from theory. I don't mean that important experiments can't be done on high-energy gas pedals; what I'm saying is that there are key meaningful developments that have to come from physical concepts."

In 2016, the debate over whether China should build a large high-energy gas pedal once attracted widespread social attention, and Yang was placed in the crosshairs of public opinion for his article "China Should Not Build a Very Large Collider Today". In response to Mr. Chengtong Qiu's misinterpretation that "it is therefore puzzling to say that Mr. Yang is against the need for further development of high-energy physics," Yang clearly pointed out: "Professor Qiu's understanding is wrong! I am in no way opposed to the continued development of high-energy physics. What I object to is the fact that China is starting to build the Super Collider today." The subject of why Yang opposes the construction of a high-energy gas pedal in China has been discussed in some detail by the author (Huang Qingqiao, "Historical Reasons for Yang's Persistent Opposition to the Construction of a High-Energy Accelerator in China," published in the July 1, 2018 issue of The Intellectual).

So, after making a pessimistic statement about the future development of high-energy physics, did Yang give his own judgment about the future development of physics discovery? In other words, what is the main theme of physics in the 21st century? In this regard, Yang gave his prediction and judgment in an accompanying note written in 2017 for an old article, "Three main themes of 20th century theoretical physics: quantumization, symmetry, and phase factor".

"With a full understanding of the possible risks involved, allow me to make some guesses as follows: due to the large number of problems facing humanity, physics in the 21st century is likely to be dominated by a variety of applied problems. These are of course very, very important, but it will lack poetic and philosophical qualities when compared with the dominant theme of the 20th century. If there is one area where there is a major fundamental revolution, I believe it will be in astrophysics. Confusions such as dark matter and dark energy will be replaced by beautiful new concepts, very similar to the replacement of Fitzgerald's contraction hypotheses by Einstein's special relativity a century ago."

Yang's prediction about the main theme of the development of physics in the 21st century has yet to be tested by the development of scientific practice, and I will not presume to comment on it. Instead, the deeper reasons for Yang's pessimistic predictions about high-energy physics are worth further exploration. The author believes that Yang's pessimistic view of high-energy physics is rooted in his conception of physics as a theoretical physicist.

Since the 20th century, along with the continuous development of experimental means and technology, especially the rapid development of high-energy gas pedal technology, physicists have gained more and more precise and profound understanding of the internal structure and laws of matter. In Yang's view, although high-energy physics in the 20th century has become more and more profound and precise, for the future, what is needed for breakthroughs in physics, especially in high-energy physics, is a revolutionary breakthrough toward physical ideas, physical concepts, and physical concepts.

Thus, he specifically emphasized that "the problem facing high-energy physics today is one of conceptual breakthroughs rather than accuracy." The further development of physics requires more work like Einstein's theory of relativity, not just the work of tinkering, verification and precise determination under the existing theoretical system.

The famous physicist David commented on Yang's physical ideas from the perspective of a "conservative revolutionary," often quoted by researchers: "As with rebuilding cities and international politics, it is easier to destroy an old structure in science than to build a lasting new one. Revolutionary leaders can be divided into two categories: like Robespierre and Lenin, who destroyed more than they created, and like Franklin and Washington, who built more than they destroyed. Undoubtedly, Young belonged to the latter category of revolutionaries; he was a conservative revolutionary. Like Franklin and Washington, he loved the past and destroyed as little of it as possible."

Another important reason for scholars to talk about high-energy physics is a controversy that took place in the United States from the 1960s onward, when high-energy physics, as an extension of nuclear physics and with the successful application of the atomic bomb and nuclear energy as a background, was considered to be the basis of all basic science and was therefore unconditionally supported by the U.S. government. In 1963, Oak Ridge National Laboratory director Alvin Weinberg published an article stating that "basic science must be useful or relevant to neighboring disciplines to be worth supporting; but the contribution of high-energy physics to neighboring disciplines (nuclear physics) is extremely limited. is extremely limited, far less than the contribution of molecular biology to its neighboring disciplines (e.g., medicine), and its contribution to technology and welfare is virtually nil."

By the early 1970s, scholars were more thorough in their critique of reductionism: "Basic research within each field, which is necessary to understand the phenomena of that field, must be supported. But reductions between different domains, because of the different scales and the complexity involved, cannot lead to a reconstruction of complex domains from simple ones. Thus, particle physics, despite being the most fundamental field in the reductionist sense, can offer little help to the study of other fields and thus should not enjoy any privilege." Yang is a witness to this ongoing debate, and it is clear that he is clearly leaning toward the opposing viewpoint, opposing the granting of special privileged status to high-energy physics, and thus being pessimistic about its development.

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Application oriented.

Suggestions for the development of science and technology in China

A direct result of Yang's pessimistic views and predictions about high-energy physics has been the spread and influence of his views in China, and the recommendations for China's science and technology development strategy based on his ideas.

In March 1980, Yang gave a lecture at the Shanghai Science and Technology Association. In response to the fact that relatively few students took chemistry in the 1979 national college entrance examination, he said, "This is something I cannot understand. I was studying particle-theoretical physics. Particle theory physics is a very important subject. I believe that in 30, 50 or 100 years from now, it will definitely be relevant to the daily life of human beings, and the study of elementary particles is going to affect the productivity of the world. However, this is from a long-term view. The distribution of long-term and short-term investments is different from country to country, and cannot be generalized. In China, if the emphasis on my line of work is too high, it will have an adverse effect, perhaps making many people who should study chemistry want to study elementary particles, and this kind of problem is not a general problem." As can be seen, Yang especially emphasized that the strategy of developing basic research should be different for different countries and at different stages of development.

At the end of 1981, Yang wrote a letter to the national leaders, offering his views on the development of science and technology in China, which was later published in the Guangming Daily on March 5, 1982. Yang noted that scientific research in China "tends to go to two extremes: either too much attention to the study of principles or too much attention to the study of products (manufacturing and improvement). Developmental research, which lies between these two kinds of research, does not seem to be focused on." "Principled research is a long-term investment, with results that will enhance the productivity of society perhaps 30 or 50 or 100 years from now (research in high-energy physics is a classic example of principled research)." "Developmental research is a medium-term investment, with the hope that the results will enhance the productivity of society in five, ten or twenty years. This kind of investment I think is a very weak link in the current Chinese science and technology research system." "The results of principle research are often famous and well known, while developmental research is seen as wealthy by the plants and refuses to be made public, so it is easy to get the rather false impression in China that there is much more funding for principle research than for developmental research in the United States. The truth is just the opposite."

Yang also pointed out that developmental research funding in the United States is about 10 times greater than principle-based research funding. "Social support for principle-based research has only started in the United States in these 30 years. This sequence of historical development, actual before principle, short and medium term before long term, is determined by economic laws and is definitely not accidental." In short, Yang suggested that China should vigorously carry out developmental research and put forward specific suggested measures. It should be said that this letter offers highly instructive and constructive advice for China's science and technology development from the perspective of the doctrinal level, China's practicality, and learning from international experience.

In May 1984, Yang told Chinese scholars in the United States: "Each different society needs different technological development, and can develop in different directions. Since my first visit to the new China in 1971, I have constantly suggested that Chinese students studying physics here (note: in the United States) need to put more effort into paying attention to the direction of physics that China needs. The high-energy physics that I am working on is not the direction that China needs urgently, it is the direction that costs money and does not make money. What kind of direction is more appropriate for China? For example, the development of solid state physics is more in line with China's national conditions."

When Yang visited Peking University in late 1984, in response to a student's question about the gap between China and foreign countries in theoretical physics, Yang said, "I don't know how to answer this question. I would say that the problems faced by theoretical physics are not the problems that China is currently trying to solve. Theoretical physics seems to be very hot in China, which is a superstition." In a talk in Shanghai in July 1985, Yang pointed out that "China needs two kinds of talents for its development: those who are engaged in basic theoretical research, who provide the theoretical basis for the development of science and technology, and the number need not be large; and those who are good at hands-on work, who can use the knowledge of the century to solve production problems, economic problems, and social problems, and the number is large. "

During his visit to the graduate school of the University of Science and Technology of China in late May and early June 1986, Yang gave a lecture in which he said, in response to questions from students and faculty, "I suspect that the next 30 years will be a difficult time for high-energy physics. That doesn't mean there's no important work or no one left to do it, but it's no longer a booming situation." "Particle physics experiments are becoming more and more expensive, and it is inevitably going to go downhill in the next 30 years. With fewer and fewer experiments, there are many people doing theory, many of them bright people, so that the tendency to become more and more mathematical is inevitable."

In response to the realities and urgent needs of China, he advised very strongly: "For many years, I have told some people who study physics that unless you feel absolutely compelled to study high-energy physics, it is better not to study high-energy physics. High-energy physics has nothing to do with China's 'quadrupling', and it's even counterproductive, because high-energy physics is too expensive. That doesn't mean that high-energy physics is not important, of course it is, but China's problem is a 'quadrupling' problem not a high-energy physics problem."

As Yang himself said, his views have remained unchanged for decades, so much so that in June 2017 he still argued in an interview that "the biggest difference between today's physics and the physics of my youth and my middle age is that I am afraid that what we can see today is that in the next 30 to 50 years there will be great development in some applied, extremely fundamental physics. research, which is not likely to develop in 30 to 50 years. Most physicists, especially those who are now studying in physics graduate schools, do not understand this difference, so I often urge people to pay more attention to this point."

This article is rewritten from the author's article "The Feast is Over: Yang's Unique View on High Energy Physics and Its Impact in China" published in Science and Culture Review, Vol. 1, 2022.