Chapter 72

I don't think it's written very well recently. There's no passion. On the last day of the May Day holiday, I'd better take a day off and update it normally tomorrow.

After all, the author is not Zhang Yuan. He can explode his liver all day. He doesn't know that he is tired and needs a normal rest... (I also seem to become him, QAQ)

Finally, another popular science article, an article written by an academician, feels very good. If you are interested, you can have a look.

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Opinions on the construction of large Collider in China

He Zuoxiu, researcher of Institute of theoretical physics, Chinese Academy of Sciences and academician of Chinese Academy of Sciences

Author he Zuoxiu (researcher, Institute of theoretical physics, Chinese Academy of Sciences, academician, Chinese Academy of Sciences)

Editor in charge: LV Haoran

one

The cepc-sppc project proposed by Wang Yifang, director of Institute of high energy physics, Chinese Academy of Sciences, and others is not an innovative project. The overall design idea is based on LHC and enlarged, and the project fund is also very large. The planned energy of SSC project in the United States is 20tev; Italy, that is, Europe once had a larger eliosatron project than the SSC of the United States, with higher planned energy. At present, the energy of SPPC proposed by Wang Yifang is 70-100tev, which is actually similar to that of eliosatron, which died without discussion in many countries, that is, it was opposed by many high-energy physics scholars in Europe.

The United States launched a fierce debate on SSC, and finally the dispute went to Congress, which voted and finally rejected it. Some people say that this is the victim of the political debate between the two parties, right! For the decision-making of SSC project, the financial personnel actually in charge of the state believe that this project does not have much scientific value, and the cost is huge, which will affect the national development capacity, so it is finally abandoned. Of course, many high-energy physicists support it, but many high-energy physicists insist on opposing it and think it is a big waste! Finally, Congress adopted the opposition and voted against it.

It should also be noted that the thoroughness of the US "veto" is surprising! The US government has invested US $2 billion, mainly to dig a large tunnel. In the plan, the cost of the tunnel accounts for about 10% of the total cost. Subsequently, an additional $15-20 billion was requested in order to achieve the final goal.

But the result is that Congress would rather sacrifice $2 billion than allow such unproductive investment. After the Congressional veto, even the excavated tunnels were filled in and no "resurgence" was allowed.

two

Why did the US Congress question the opinions of many experts and finally veto the SSC project after the Congress debate? Another important academic reason is that there is an important theory in the theory of particle physics, that is, particle physics will develop to ultra-high energy physics and there will be no new discoveries. This is called the "big desert" theory of high energy physics.

The "great desert" theory holds that new discoveries in high-energy physics are possible only if the energy is at least raised to the Planck scale, that is, the energy equivalent to 10 ^ 16tev. Later, some high-energy physics scholars believed that this theory was not completely correct and should be revised. The correction method is to introduce the concept of "supersymmetry", and think that with these supersymmetric particles, the energy scale will be reduced by many orders of magnitude, but it is still much higher than that proposed by SPPC! Later, several accelerators in the United States and Europe tried to find these supersymmetric particles, but they got nothing. This also explains the rationality of the "great desert" theory. Therefore, the U.S. Congress overwhelmingly rejected the continuation of the SSC project.

Of course, the "disappearance" of supersymmetric particles immediately led to a major fundamental change of view, that is, the superstring theory carefully prepared by many particle physicists and mathematicians also "collapsed"! The so-called "collapse" here is aimed at superstring theory, which is meaningless in physics. However, it is not excluded that it has certain significance in mathematics.

However, a considerable number of theoretical physicists who do superstring theory and supersymmetric particles do not think supersymmetry is dead and are still insisting. However, few people believe that this is a promising theory in particle physics, and they have announced that they will "change their profession". For example, Professor Li Miao of the Institute of theoretical physics, who has made great contributions to superstring theory, has now given up. In other words, superstring theory is not the mainstream of high energy and particle science!

three

Combining the above two discussions, I can only think that the cepc-sppc scheme proposed by director Wang Yifang is just an "innovation" that has been completely abandoned by the US Congress, but at this time, it was taken by many scientists to sell it to the Chinese government.

As for whether the Chinese government is willing to invest heavily in construction, it depends on how the Chinese government evaluates the matter.

We should also note that many of the people promoting the collider project are American experts such as academicians of the American Academy of Sciences, who said that this scheme has "many benefits". Of course, because the research of high-energy physics in China is far less advanced and developed than that in the United States, perhaps we are "short-sighted" and lack scientific foresight. However, there is still a question that I can't understand: why is such a good scheme not accepted by the American scientific and technological community? Why does such a good plan not insist on lobbying the US government? If the U.S. government announces that it will launch this "innovative" program and hopes that China can also contribute a large amount of funds to join the cooperation, I believe it will get the full support of many scientists in China's high-energy physics community!

four

One answer to our question is that this scheme is still of far-reaching significance for the research of high-energy physics in developing countries, such as China. I can't agree with that. We have always been in favor of the saying that "science has no borders and scientists have the motherland". We can't agree with a plan that is of "great significance" to the motherland of Chinese scientists but has little significance to world science. There are too many scientific problems to be solved in contemporary China, and many young people need to participate in this work. However, we should not conceive a plan that is not very "effective" to resettle these high-energy physics scholars because several people in China or other countries in the world have entered the high-energy physics field but lack jobs!

The world is a whole. The economic and scientific development of all countries in the contemporary world must take the road of "integration" and "globalization". Recently, I am engaged in the study and research of economics and political economics in my spare time. Many conclusions of economics should also apply to the development of world science.

We know that there is a law of diminishing marginal utility in economics, which can be applied to a wide range. For example, why did China's economy rise from an earlier average of 10% to 6.9% today? The simplest explanation is diminishing marginal utility. The way to mitigate this impact is to rely on innovation. These basic principles must also be applicable to the research of high energy physics.

From the proposal of Wang Yifang and others, the feature of this scheme is that there is no revolutionary technological innovation at all and only develops towards "super large", so it must be applicable to the law of diminishing marginal utility.

There is a technical difficulty in applying the law of diminishing marginal utility, that is, it is difficult to judge at what speed the "marginal utility" is "diminishing", and how much will its "marginal", that is, the "slope" be "reduced" in the future? In fact, recent LHC experiments have given a judgment.

In the previous period, LHC found a "resonance peak" of 750 GeV in the energy range of 700-800 GeV. The academic community is very excited, because it seems that there may still be new discoveries in high-energy physics, and the theory of "great desert" is inconsistent with reality! However, due to the insufficient number of experiments, it is not clear that this is a new particle. Therefore, some people advocate investing more operation time and cost in order to fish out the "new particle". A large number of theorists believe that this is a new thing, and have made many "new" theories to explain the particle and make all kinds of new predictions.

However, most theoretical physicists who insist on believing in the "great desert" theory still believe that the so-called "new particle" should be a statistical fluctuation, not a new particle.

As a result, further high-precision experiments show that the existence of "new particles" has not been confirmed“ The "great desert" theory is still correct in this energy region. It should be noted that the energy of 750 GeV is actually six times that of 125 GeV of the Higgs particle called "God particle", but the result is still zero. If interpreted in economic terms, this experiment has shown that the "marginal utility" of the high-energy Collider in the energy region of LHC has decreased to "zero".

Now, in the scheme proposed by Wang Yifang, the maximum energy is only 7 times that of LHC. If we continue to follow this trend, how can we ensure the discovery of new particles or other major new things? Moreover, the Geneva center will further increase its energy to 20tev and continue to engage in experimental work. However, Geneva already has super large accelerators, and the west can achieve marginal benefits only by reinvesting some money. However, China has to restart the stove, which is just to increase the energy by 7 times, but it has to go through the long process of LHC in the center of Geneva.

In other words, the scheme of Wang Yifang and others is by no means an equal competitor of Geneva.

The LHC of the Geneva center has made great contributions to high energy physics. It has operated for 20 years, found four important particles successively, and almost completely proved the correctness of the "standard model". Now there is only one small problem left, that is, whether the lepton number is "absolute" conservation has not been completely solved. However, the answer to this question does not require ultra-high energy accelerators, but medium and low energy accelerators, such as spallation neutron source, ads and other projects approved by the Academy of Sciences.

It can be said that the current development trend of high-energy physics fully corresponds to the supply curve repeatedly emphasized by Premier * * * and will extend to the "right" according to the "s" character. At this time, there are "great desert" theory and LHC experimental results, which show that the extended "marginal utility" is almost close to zero, that is, the "s" shaped curve is close to the "vertex".

Then, why should China make a major investment in cepc-sppc, which is difficult to produce significant results?

five

Of course, director Wang Yifang has always stressed that the high energy institute has never overspent when building the positron collider, and the fluctuation range will not exceed 5%. It should be said that this is a historical fact. As a witness of the Beijing Electron Positron Collider, I have to tell some stories behind it.

The Electron Positron Collider built by the Institute of high energy was a large-scale basic research project of trump by Comrade * * * according to the last wish of Premier Zhou after the "Cultural Revolution", with a total cost of 220 million yuan. Since this is the first large-scale scientific research project specially approved by the central government after the reform and opening up, the central government once came forward to say hello to all parties: This is not a "Tang Monk meat", and all ministries and commissions cannot take the opportunity to "bite". This "greeting" also spread to Hong Kong, which has not yet returned. The industry in Hong Kong said that this is a project specially approved by Comrade Xiaoping, and we will strongly support it. Even if we don't make money, we will try to ensure supply.

In order to ensure that the positron collider is carried out as planned, the Central Committee also assigned Comrade Gu Yu, the wife of Comrade Hu Qiaomu, to preside over and take charge of this work. In case of difficulties, Comrade Gu Yu coordinated from them. For example, when the construction of the electron positron collider started, nearby residents were worried about radioactive pollution and opposed it. Therefore, the environmental protection department sent a department level cadre to participate in supervision. However, the cadre's professional knowledge reserve was insufficient, and he just blindly opposed it.

We asked her to come up with a corresponding "index" and what criteria should be reached before it can be passed, but she couldn't give a specific value. At that time, the leader of the Institute entrusted me to organize some young comrades to design the protective device of the high-energy accelerator. Because the cadre sent by the environmental protection department was really "layman", she could not give a specific index, and of course, we also suspected that she meant to "bite".

Therefore, Comrade Gu Yu went to Comrade Xiaoping to report the situation, and finally Comrade Xiaoping decided that we should be responsible.

Of course, our design was finished soon. Because this collider is an electron positron collider, it only emits X-rays and electrons γ Radiation has less impact on the environment than cosmic ray background.

The question is, in the current era, can Wang Yifang's "wishful thinking" be realized again? The conclusion should be: This is a scheme that is not suitable for China's national conditions and should not be supported by policymakers.

six

Director Wang Yifang also said that almost all the opponents are experts outside the field of high energy physics. I don't think that's true.

We also have a group of members of the society of high energy physics here (Institute of Theoretical Physics), many of whom oppose it. In fact, there are some different opinions within the Institute, but due to the kindness of colleagues, I am embarrassed to publish them publicly.

Before that, Professor Yang Zhenning published an article against China's construction of large-scale collider. Some people also pointed out that Mr. Yang has not been in the front line of physics for many years and deviated from the mainstream of physics. These doubts are not correct. Although Professor Yang is old and has not been on the front line for many years, Mr. Yang's views on theoretical physics can not be said to be outdated or deviate from the mainstream. Historically, Mr. Yang's judgment on the future of physics can not be said to be insignificant.

Recently, director Wang Yifang proposed that almost all high-energy experimental physicists are in favor of China's construction of the large-scale collider project. The opponents are theoretical physicists, and raised some questions about the opponents' majors, including Professor Yang Zhenning, who is not an experimental physicist.

OK, let me also list Professor Ding Zhaozhong, a scholar who can definitely be called a high-energy physics experimenter in the world and a teacher of Wang Yifang's director. Professor Ding once asked me what research Wang Yifang is doing now. I replied that he is still measuring neutrino oscillations in Daya Bay. In addition, he is studying some new schemes. Professor Ding asked what was the new plan? I said that he wanted to move the similar scheme of SSC discussed in the United States to China. Professor Ding immediately said, why do you want to do this? It's not interesting at all!

I'm sorry to make Professor Ding Zhaozhong's opinion public here. But I think this is enough to prove that there are still some internationally renowned high-energy physics experimenters who do not support his scheme.