I feel like I've not written very well lately.,There's no passion.,The last day of the May Day holiday.,It's better to take a day off.,Update it normally tomorrow.。

After all, the author is not Zhang Yuan, who can burst his liver all day long and does not know that he is tired, and he needs to rest normally...... (I also seem to have become him, QAQ)

Finally, let's have a popular science article, an article written by an academician, it feels pretty good, and if you are interested, you can take a look.

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Opinion on the construction of a large collider in China

He Zuoxiu, a researcher at the Institute of Theoretical Physics of the Chinese Academy of Sciences and an academician of the Chinese Academy of Sciences

He Zuoxiu (Researcher, Institute of Theoretical Physics, Chinese Academy of Sciences, Academician of Chinese Academy of Sciences)

Editor-in-charge|Lu Haoran

1

The CEPC-SPPC project proposed by Wang Yifang, director of the Institute of High Energy Physics, Chinese Academy of Sciences, and others is not an innovative project, and the overall design idea is borrowed from the LHC and amplified, and the project funding is also very large. the SSC project in the United States, with a planned energy of 20TeV; Italy, i.e. Europe, had a larger Eliosatron project than the SSC in the United States, with higher energy plans. The SPPC proposed by Wang Yifang is now 70-100 TeV, which is actually similar to Eliosatron's, which was opposed by many high-energy physicists in Europe without discussion in many countries.

The United States engaged in a heated debate for the SSC, which finally went to Congress, where it voted and finally vetoed. Some people say that this is a victim of the political debate between the two parties, right! As for the decision-making of the SSC project, the people who are actually in charge of the state finance believe that the project does not have much scientific value, and the cost is huge, which will affect the country's development capacity, so it is finally abandoned. Of course, there are many high-energy physicists who support it, but there are also many high-energy physicists who insist on opposing it, thinking that it is a big waste! In the end, Congress adopted the opposing side's argument and voted against it.

It should also be noted that the depth of the US "veto" is astonishing! The U.S. government has invested $2 billion, mainly to dig a large tunnel, which is planned to cost about 10 percent of the total cost. Later, an additional $150~20 billion was requested for eventual realization.

But as a result, Congress would rather sacrifice the $2 billion it should have spent than allow such unproductive spending. After the congressional veto, even the excavated tunnels were filled in, and "resurgence" was not allowed.

2

Why did the U.S. Congress question the opinions of a number of experts and finally veto the SSC project after a congressional debate? There is another important reason in the academic field: 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, which is called the "great desert" theory of high-energy physics.

The "Great Desert" theory suggests that new discoveries in high-energy physics can only be made if the energy is at least increased to the Planck scale, that is, the energy equivalent to 10^16 TeV. Later, some high-energy physicists argued that this theory was not entirely correct and should be revised. The solution is to introduce the concept of "supersymmetry", and think that with these supersymmetric particles, their energy scales will be reduced by many orders of magnitude, but still much higher than those proposed by SPPC! Later, several accelerators, such as in the United States and Europe, tried to discover these supersymmetric particles, but found nothing. This also illustrates the rationality of the "Great Desert" theory from the side. Therefore, the US Congress, with an overwhelming vote, vetoed the continuation of the construction of the SSC project.

Of course, the "disappearance" of supersymmetric particles also immediately led to a major fundamental shift in perception, that is, the "collapse" of many superstring theories crafted by particle physicists and mathematicians! The so-called "downfall" here is aimed at theories that superstring theory makes no sense in physics. However, it is not excluded that it has some mathematical significance.

However, there are still a considerable number of theoretical physicists who do superstring theory and supersymmetric particles do not think that supersymmetry is dead and still insist on it. However, few people no longer believe that this is a promising theory in particle physics, and they have announced that they will not do it. For example, Professor Li Miao, who contributed to superstring theory at the Institute of Theoretical Physics, has now given up on not doing it. In other words, superstring theory is no longer the mainstream in the field of high energy and particle science!

3

Combining the above two arguments, I can only think that the CEPC-SPPC proposal proposed by Director Wang Yifang is nothing more than an "innovation" that has been completely abandoned by the US Congress, but at this time, many scientists have taken it and sold it to the Chinese government.

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

It should also be noted that many of the people who promoted the collider project were American experts, such as academicians of the National Academy of Sciences, who said that the program had "many benefits". Of course, because China's research on high-energy physics is far less advanced and developed than that of the United States, perhaps we are "blind" and have no scientific foresight. However, there is still one question that I cannot understand: why is such a good solution not accepted by the American tech community? Why does such a good plan not insist on continuing to lobby for the US government? If the U.S. government announces that it will launch this "innovative" plan, and hopes that China will also contribute a large amount of funds to join the cooperation, I believe that it will definitely receive the full support of many scientists in China's high-energy physics community!

4

One answer to our question is that this solution is still of far-reaching significance for the research of high-energy physics in developing countries, such as China. I disagree. We have always been in favor of the phrase "science knows no borders, and scientists have a motherland", and we cannot agree to a program that is of no great significance to world science, but will have any "great significance" to the motherland of Chinese scientists. There are so many scientific problems that need to be solved in contemporary China, and there are many, many young people who need to participate in this work. But just because there are already a number of people in China or other countries around the world who have entered the high-energy physics community, but there is a lack of jobs, we can't come up with a plan that is not very "effective" to resettle these high-energy physicists!

The world is one. The economic and scientific development of all countries in the world today will inevitably follow the road of "integration" and "globalization." Recently, I have been engaged in the study and research of economics and political economy in my spare time. Many of the conclusions of economics should also be applied to the development of world science.

We know that there is a law of diminishing marginal utility in economics, and this law can be applied to a wide range. For example, why has China's economy changed from an average growth rate 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 are also inevitably applicable to the study of high-energy physics.

From the proposal of Wang Yifang and others, this scheme is characterized by 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 determine at what rate the "marginal utility" will "decrease", and how much will it "decrease" in the future "margin", that is, the "slope"? In fact, recent experiments with the LHC have already given a verdict.

In the previous period, the LHC found a 750 GeV "formant peak" in the 700-800 GeV energy range. The academic community is very excited, because it seems that there may still be new discoveries in high-energy physics going "high", and the theory of the "Great Desert" does not match the reality! However, due to the insufficient number of experiments, it is not clear that this is a new particle. As a result, some advocate investing more time and money in order to get this "new particle" out. There are also a large number of theorists who believe that this is a new thing, and have made many "new" theories to explain this particle, and have made all kinds of new predictions.

However, most theoretical physicists who insist on the "Great Desert" theory still believe that this so-called "new particle" should be a statistical fluctuation, not the discovery of a new particle.

As a result, further high-precision experiments showed that the existence of "new particles" was not confirmed! The "Great Desert" theory is still true in this energy zone. It should be noted that the 750GeV energy is actually 6 times that of the Higgs particle, known as the "God particle", 125GeV, but the result is still zero. In economic terms, this experiment has shown that the "marginal utility" of the High Energy Collider in the energy region of the LHC has been reduced to "zero".

Now, in the scheme proposed by Wang Yifang, the maximum energy is only 7 times that of LHC. And if we continue to follow this trend, how can we ensure that new particles or other major new things are discovered? Not only that, but the Geneva Center is about to further increase its capacity to 20 TeV and continue to work on experiments. But Geneva already has mega-accelerators, and the West only needs to reinvest some money to achieve marginal benefits. China, on the other hand, wants to restart the stove, which is only to increase the energy by a factor of seven, but it will have to go back to the long journey that the LHC in the center of Geneva has already taken.

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

The contribution of the LHC at the Geneva Centre to high-energy physics is enormous, as it has been in operation for 20 years, has discovered four important particles, and has almost completely proved the correctness of the "Standard Model". Now only one small question remains, that is, the question of whether the lepton number is "absolutely" conserved has not been completely resolved. However, the answer to this question does not require ultra-high-energy accelerators to be studied, but medium- and low-energy accelerators, such as the Spallation Neutron Source and ADS projects that have been approved by the Academy of Sciences.

It can be said that the current development trend of high-energy physics, which is completely corresponding to the supply curve that has been repeatedly emphasized, will extend to the "right" according to the "S" trait. At this time, the "Great Desert" theory and the experimental results of the LHC have shown that the "marginal utility" of this extension is roughly close to zero, that is, the "S" shaped curve is close to the "vertex".

So, why is it necessary for China today to make a major investment in this CEPC-SPPC, which is difficult to produce significant results?

5

Of course, Director Wang Yifang has always emphasized that the Positron Collider has never been 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 Positron Collider, I would like to tell you some of the stories behind it.

The Positron Collider built by the High Energy Institute was a large-scale basic research project built by Comrade *** according to Premier Zhou's last wish 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 has come forward to greet all sides: This is not a piece of "Tang monk meat", and various ministries and commissions should not take the opportunity to "take a bite". This "greeting" also spread to Hong Kong, which had not yet returned to China at that time. The industry in Hong Kong said that this is a project specially approved by Comrade Xiaoping, and we will definitely give strong support, and even if it is not profitable, we will try to ensure the supply.

In order to ensure that the positron collider proceeds as planned, the central authorities have specially appointed Comrade Gu Yu, the wife of Comrade ******* Hu Qiaomu, to preside over and take charge of this work. When difficulties are encountered, Comrade Gu Yu coordinates them. For example, when the construction of the Positron Collider began, nearby residents expressed their opposition for fear of radioactive contamination. As a result, the environmental protection department sent a department-level cadre to participate in the supervision. However, the cadre's professional knowledge reserve was insufficient, and he just blindly expressed his opposition.

We asked her to come up with a corresponding "indicator" on what standard she should meet in order to pass, but she couldn't give a specific value. At that time, the leaders of the high-energy institute entrusted me to organize some young comrades to design the protective device of the high-energy accelerator, but because the cadre sent by the environmental protection department was really a "layman", he could not give a specific target, and of course we suspected that she had the meaning of "taking a bite".

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

Of course, our design was completed very quickly. Because this collider is a positron and negative electron collider, it emits only X-rays and γ rays, and its impact on the environment is even smaller than that of the cosmic ray background.

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

6

Director Wang Yifang also said that the opponents are almost all experts outside the field of high-energy physics. I guess that's not true.

We also have a group of members of the Society for High Energy Physics here (Institute of Theoretical Physics), and many of them are against it. In fact, there are some different opinions within the institute, but they are embarrassed to express them publicly because of the feelings of their colleagues.

Previously, Professor Yang Zhenning published an article opposing China's construction of a large collider, and some people also pointed out that Mr. Yang has not been on the front line of physics for many years, deviating from the mainstream of physics. Although Professor Yang is old and has not been on the front line for many years, Mr. Yang's views on theoretical physics cannot be said to be outdated or deviate from the mainstream, and from a historical point of view, Mr. Yang's judgment on the future of physics cannot be said to be insignificant.

Recently, Director Wang Yifang pointed out that almost all high-energy experimental physicists are in favor of China's construction of the Large Collider project, and the opponents are all theoretical physicists, and raised some doubts about the profession of the opponents, including Professor Yang Zhenning, who is not an experimental physicist.

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

I'm sorry that I've made Professor Ding's opinion public here. But I think this is enough to prove that there are still some internationally renowned experimentalists in high-energy physics who do not support his plan.