Deep Space Planet Leader

I feel that I have not written very well recently, and there is no passion. On the last day of the May 1st holiday, let’s take a day off and update normally tomorrow. & lt;/p>

After all, the author is not Zhang Yuan. He can burst his liver all day long without knowing that he is exhausted and needs a normal rest... (I also seem to be him QAQ)

Finally, here is a popular science article, an article written by an academician, which feels pretty good, and you can read it if you are interested.

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Opinions on the construction of a large-scale collider in China

Researcher at the Chinese Academy of Sciences Institute of Theoretical Physics, He Zuoxiu, academician of the Chinese Academy of Sciences

Writing|He Zuoxiu (Researcher of the Chinese Academy of Theoretical Physics, Academician of the Chinese Academy of Sciences)

Editor in charge|Lu Haoran

1

Chinese Academy of Sciences High Energy The CEPC-SPPC project proposed by Wang Yifang, Director of the Institute of Physics and the others, is not an innovative project. The overall design idea is borrowed from LHC and enlarged, and the project funding is also very large. The US SSC project has a planned energy of 20 TeV; Italy, that is, Europe once had a larger Eliosatron project than the US SSC, with a higher planned energy. The energy of the SPPC proposed by Wang Yifang is 70-100 TeV, which is actually similar to that of Eliosatron, and the latter has not been discussed by many countries, that is, it has been rejected by many high-energy physics scholars in Europe and died.

The United States launched a fierce debate for the SSC, and finally the dispute reached the Congress, which was voted by Congress and finally vetoed it. Some people say that this is a victim of political disputes between the two parties, which is wrong! Regarding the decision-making of the SSC project, the patriarch financial staff of the country believed that the project did not have much scientific value, and the cost was huge, which would affect the country's development capacity, so it was eventually abandoned. Of course, many high-energy physicists expressed support, but there were also many high-energy physics scholars who insisted on opposing it, thinking it was a big waste! In the end, Congress adopted the opposing party's opinion and voted to reject it.

It should also be noted that the thoroughness of the US "veto" is surprising! The U.S. government has invested US$2 billion, mainly for digging a large tunnel. In the planning, the cost of the tunnel accounts for about 10% of the total cost. Later, it asked for an additional 15-20 billion US dollars in order to finally realize it.

But it turned out that Congress would rather sacrifice the $2 billion that should be invested than it would no longer allow such unprofitable investments. After the Congress vetoed it, even the excavated tunnels were filled in, and the "resurgence" was not allowed.

2

Why did the U.S. Congress question the opinions of many experts and finally rejected the SSC project after the Congressional debate? There is another important academic reason: there is an important theory in the theory of particle physics, that is, the development of particle physics to ultra-high energy physics, and there will be no new discoveries. This is called the "great desert of high energy physics". "Theory.

The "great desert" theory believes that at least the energy must be increased to the Planck scale, that is, the energy equivalent to 10^16TeV, before new discoveries in high energy physics are possible. 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 believe that with these supersymmetric particles, the energy scale will be reduced by a lot of magnitude, but it is still much higher than the magnitude proposed by SPPC! Later, several accelerators in the United States and Europe tried to find these supersymmetric particles, but found nothing. This also illustrates the rationality of the "great desert" theory from the side. Therefore, the US Congress rejected the continued construction of the SSC project by an overwhelming number of votes.

Of course, the "disappearance" of supersymmetric particles also immediately led to a major and fundamental change in opinion, that is, the superstring theory elaborated by many particle physicists and mathematicians also "collapsed." ! The so-called "downfall" here refers to the theory that superstring theory is meaningless in physics. However, it cannot be ruled out that it has a certain meaning in mathematics.

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

3

Combining the above two discussions, I can only think that the CEPC-SPPC plan proposed by Director Wang Yifang is nothing but 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 the Chinese government’s willingness to invest heavily in construction, it depends on how the Chinese government evaluates the matter.

We should also note that many of the people who promote the collider project are American experts such as academicians of the American Academy of Sciences. They said that this program has "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 it is the short-sightedness of those of us who have no scientific foresight. However, there is still a question that I can’t understand: Why is such a good solution not accepted by the American science and technology community? Why is such a good plan not insisting on continuing to lobby 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 it will definitely receive the full support of many scientists in my country's high-energy physics community!

4

For our doubts, one answer is: This program still has far-reaching significance for the research of high energy physics in developing countries, such as China. I cannot agree with this. We have always agreed with the saying "Science knows no borders, and scientists have a motherland". We cannot agree to a plan that has no significance to world science but has "great significance" for the motherland of Chinese scientists. There are too many scientific problems to be solved in contemporary China, and many, many young people are required to participate in this field. However, because there are already a few people in China or other countries in the world who have entered the field of high-energy physics, but there is a lack of jobs, a plan that is not very "effective" can be conceived to arrange these high-energy physics scholars!

The world is a whole. The economic and scientific development of countries in the contemporary world will inevitably follow the path of "integration" and "globalization". Recently, I have been engaged in the study and research of Economics and Political Economics in my spare time. Many conclusions of Economics should also be applicable to the development of world science.

We know that Economics has a law of diminishing marginal utility, which can be applied to a wide range. For example, why has my country's economy changed from an average increase of 10% earlier to 6.9% today? The simplest explanation is diminishing marginal utility. The way to alleviate this impact is to rely on innovation. These basic principles must also be applicable to the study of high-energy physics.

From the proposal of Wang Yifang and the others, the feature of this scheme is that there is no revolutionary technological innovation at all, and it 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" "decreases", and its "margin", that is, the "slope" will "decrease" in the future. How much? In fact, the recent LHC experiment has already given a judgment.

In the previous period, LHC found a "resonant peak" of 750GeV in the energy range of 700-800GeV. The academic community is very excited, because it seems that there may be new discoveries in high-energy physics to "go high", 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 operating time and expenses in order to fish out this "new particle". There are also a large number of theorists who think this is a new thing, and they have made many "new" theories to explain this particle and made various 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 that a new particle has been discovered.

As a result, further high-precision experiments have shown that the existence of "new particles" has not been confirmed! The "great desert" theory is still correct in this energy zone. It should be noted that the energy of 750GeV is actually 6 times that of 125GeV of the Higgs particle called the "God particle", but the result is still zero. If interpreted in the terms of Economics, this experiment has shown that the “marginal utility” of the high-energy collider in the LHC energy zone has diminished 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, the Geneva Center is about to further increase the energy to 20 TeV and continue to engage in experimental work. But Geneva already has super-large accelerators, and the West only needs to reinvest some money to achieve marginal benefits. However, China has to restart the stove, which is only to increase the energy by 7 times, but it has to retake the long journey that the LHC in Geneva center has gone through.

Or Wang Yifang and the others' plan is by no means an equal competitor in Geneva.

The LHC at the Geneva Center has made a huge contribution to high-energy physics. It has been in operation for 20 years and has discovered four important particles, and it has almost completely proved the correctness of the "Standard Model". Now there is only a small question left, that is, whether the lepton number is "absolutely" conserved and has not yet been completely resolved. But the answer to this question does not require ultra-high-energy accelerators to study, but requires low- and medium-energy accelerators, such as the spallation neutron source, ADS and other projects that have been established by the Academy.

It can be said that the current development trend of high energy physics completely corresponds to the supply curve repeatedly emphasized by the Prime Minister of China, and will extend to the "right" according to the "S" character. At this time, there are already "great desert" theory and LHC experimental results, which show that the "marginal utility" of this extension has been roughly close to zero, that is, the "S"-shaped curve is close to the "peak". ".

So, why does today's China need to invest heavily in this CEPC-SPPC, which is difficult to produce great achievements?

5

Of course, Director Wang Yifang has always emphasized that the high-energy electron-positron collider has never been overrun, 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 want to tell some stories behind it.

The electron-positron collider built by High Energy is a large-scale basic research project developed by Comrade *** based on Premier Zhou’s wishes after the "Cultural Revolution". The total cost is 220 million Renminbi. 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 parties: this is not a piece of "longevity meat", and various ministries and commissions cannot take the opportunity to "eat a bite." This "greet" 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 support it. Even if it does not make money, we will try to ensure the supply.

In order to ensure that the electron-positron collider proceeded as planned, the Central Committee also dispatched the wife of ******* Comrade Hu Qiaomu, Comrade Gu Yu, to preside over and take charge of this work. When encountering difficulties, Comrade Gu Yu coordinated. For example, when the construction of the electron-positron collider was started, nearby residents were worried about radioactive contamination and expressed their opposition. As a result, the environmental protection department sent a division-level cadre to participate in the supervision. However, the cadre did not have sufficient reserves of professional knowledge and he merely expressed his opposition.

We asked her to come up with a corresponding "indicator", what kind of standard should be reached in order to pass, but she can not give a specific value. At that time, the leaders of the High Energy Institute commissioned me to organize some young comrades to design the protective devices for high-energy accelerators. Because the cadre from the Ministry of Environmental Protection Sect was really an “outer,” he could not give a specific indicator. Of course, we also suspected that she had “chewed”. "One bite" means.

So, 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 quickly completed. Because this collider is a electron-positron collider, it only emits x-rays and gamma 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 Wang Yifang's "wishful thinking" be realized again? The conclusion should be: This is a plan that does not fit China's national conditions, and policymakers should not support it.

6

Director Wang Yifang also stated that the opponents are almost all experts in the High Energy Physics field of Foreign Domain. I think this is by no means true.

We (Institute of Theoretical Physics) also have a group of members of the Society of High Energy Physics, many of whom oppose it. In fact, there are also some different opinions within the High Energy Institute, but they are due to the feelings of colleagues.

Before Professor Yang Zhenning published an article against China’s construction of a large-scale collider, some people also suggested that Mister 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 in the front line for many years, Mister Yang’s insights on theoretical physics cannot be said to be outdated or deviated from the mainstream. From a historical point of view, Mister Yang’s view of the future of physics The judgment cannot be said to be insignificant.

Recently, Director Wang Yifang pointed out that almost all high-energy experimental physicists are in favor of the construction of a large-scale collider project in China, and the opponents are all theoretical physicists’ arguments, and the opponent’s professionalism is proposed Some doubts have been raised, including that Professor Yang Zhenning 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 Wang Yifang—Professor Ding Zhaozhong. Professor Ding once asked me what research Wang Yifang is currently doing. I replied that he is still measuring neutrino oscillations in Daya Bay. In addition, he is working on some new solutions. Professor Ding asked what is the new plan? I said that he wanted to move the similar plan of SSC discussed in the United States to China. Professor Ding said immediately, why do you want to do this? Not interesting at all!

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