By C.N. Yang
In an article published in WeChat public account “Mr. Gu on Geometry”, titled “S. T. Yau: A few comments on the construction of high energy collider in China, and answer to questions from the media”, he said he support the construction of super collider in China, but I (Yang) am against, he can’t believe this. This is specifically mention in the following paragraph:
“The theoretical basis of all these experiments used the theory invented by Mr. Yang. My respect for him grew after each breakthrough. Therefore, it is hard to understand why Mr. Yang opposes the idea that high energy physics needs further development”.
Professor Yau has misunderstood me! I am definitely not against the further development of high energy physics. Instead, I oppose we begin to construct super big collider in China now, for the following reasons:
1) Construction of big collider has been a painful experience for the US: In 1989, it started to build the world’s largest collider. The initial budget was estimated to be 3 billion dollars, but it was added upon for several times later, reaching 8 billion dollars, which triggered a lot of opposing voice. Eventually, the congress painfully cancelled this project in 1992, wasting about 3 billion dollars. This experience led many people to believe that the construction of large collider is a bottomless money sink.
Currently, the largest collider is the LHC at CERN. In 2012, a collaboration of about 6000 physicists discovered the Higgs boson at the LHC. This is a major achievement of particle physics, verified the Standard Model. It has taken many years to construct the LHC. The total cost is no less than 10 billion dollars, including the machine and the detectors. The budget of the super big collider proposed by IHEP is certainly more than 20 billion dollars.
2) IHEP proposed to construct the super big collider in China, sharing the cost among many countries. However, China must shoulder a significant portion of it. Today, to the amazement of the world, the GDP of China has jumped to the second place in the world. However, China is still a developing country, its GDP per capita is still less than that of Brazil, Mexico or Malaysia. There are still a couple hundred millions of farmers and migrant workers. There are urgent problems to deal with, including environment, education, health and medicine, etc. The construction of the super big collider will be very costly, and hamper the solution of those urgent problems. I think we should not consider it now.
3) The construction of the super big collider will significantly squeeze the funding for other basic science, including biological science, condensed matter physics, astrophysics, etc.
4) Why is the construction of super big collider enthusiastically supported by many high energy physicists? The reasons are:
- High energy physics is a new area developed after the World War II. It has had spectacular success in the past 70 years, verified the Standard Model, enabling deep understanding of the three fundamental interactions in nature. However, there are still two unsolved big problems:
- Deeper understanding of the remaining fourth fundamental interaction, gravity, have encountered fundamental difficulties.
- It has been not possible to unify force and mass. It is certain the hope of all physicists to solve these two problems.
- Some high energy physicists hope that the super big collider can discover “supersymmetric particles”, and therefore point to the way of the solution for these two problems.
However, the search for supersymmetry has been going on for many years, with no discovery. The supersymmetric particles which they hope to find at the super big collider is only a hypothesis by a subset of high energy physicists. Most of the physicists, myself included, think the existence of supersymmetric particles is just a hypothesis without any experimental evidence. The hope to find them at the super big collider is only a hypothesis about a hypothesis.
5) What are tangible benefits to people’s life from the big achievement of the high energy physics in the past 70 years? Nothing. What are tangible benefits to people’s life if the super big collider proposed by IHEP can be built, and it can succeed in significantly advancing high energy physics? I think it is impossible in the short term, impossible in 30 or 50 years. Moreover, I know my point of view is agreed upon by the absolute majority of the physicists.
6) IHEP has been established for 30 years. How should we evaluate its achievements in this period? Among the important high energy physicists in the world, only less than 1 to 2 per cent are in China. For the super big collider, its design, construction, and the operation and data analysis after its completion, will definitely be led 90% by foreigners. If there will be Nobel prize, would it be awarded to Chinese?
7) Without the construction of the super collider, is there no future for high energy physics? No. I think there are at least two directions worth pursuing: A. Search for new accelerator design principles. B. Search for beautiful geometrical structure, such as in the research of string theory. The research in both of these directions do not cost as much money. It is suitable under the current trend of economic development of the world.
[Note: The parts in red color were marked by Prof. Yang himself.]