In 2014, China announced plans to build the world's largest and most advanced electron-positron collider, with the intention of advancing physics research by exploring the properties of elementary particles such as the Higgs particle. This ambitious project, which cost tens of billions of dollars, is supported by international partners and is a major ambition of the Institute of High Energy Physics of the Chinese Academy of Sciences. However, in the face of this world-renowned plan, the famous physicist and Nobel laureate Yang Zhenning openly expressed his opposition, and even disagreed with many domestic scientists because of this. Why would this scientist, who is a major figure in the world of physics, risk controversy and be so adamant in his opposition to this seemingly glorious project?
Origin and development of collider technology
In 1956, a group of scientists conducted a series of experiments in the laboratory on the stability and strength of electron beams. Through continuous experimentation and adjustment, they succeeded in obtaining a beam of sufficient intensity, which was a major breakthrough in the development of collider technology. Scientists have verified the feasibility of the beam in high-energy physics experiments by precisely controlling the focusing and acceleration of the electron beam.
As the technology matured, scientists began to design and build the first positron collider. Due to its relatively low cost and technical requirements, the positron collider quickly became an important tool for high-energy physics research. The design team chose a relatively simple magnetic ring structure to accelerate and store high-speed moving electrons and positrons, allowing them to produce high-energy particle fragments during the collision.
In 1961, the world's first positron collider was completed and put into operation at a research institute in the United States. The successful launch of the collider marks the beginning of a completely new scientific direction. Through collision experiments, scientists have observed a series of novel particle phenomena, and these discoveries have provided valuable data for theoretical modeling of particle physics.
Soon after, several countries in Europe and Asia also set up their own low-energy electron colliders. Although these colliders are of lower energy, they have played an important role in the fundamental research of particle physics due to technological advances. Through these facilities, scientific teams have conducted a series of innovative experiments to study the energy released and the types of particles produced when electrons and positrons collide at extremely high speeds.
Major discovery: the birth of the J/ψ particle
At the SPEAR collider at the Stanford Linear Accelerator Center in United States, scientist B. Richter and his team successfully observed a new type of particle in a high-energy experiment, which is later widely known as the J/ψ particle. The discovery was made almost simultaneously with Professor Ding Zhaozhong of the Brookhaven National Laboratory in the United States, who also independently discovered this same particle in his experiments.
In experiments at the SPEAR collider, B. Richter and his team observed anomalous energy releases and particle trajectories by precisely controlling and monitoring the collision process of electrons and positrons inside the collider. This anomaly indicates the creation of an unknown heavy particle, and after repeated experiments and data analysis, it was confirmed that these signals originated from a completely new particle, the J/ψ particle.
At the same time, Professor Ding Zhaozhong observed a similar phenomenon in Brookhaven's laboratory. Professor Ding used different techniques and methods, but came up with similar results to Richter, further verifying the correctness of this finding. The discovery was elaborated by their respective research teams in their publications and public lectures, which sparked great interest in the global scientific community.
The discovery of J/ψ particles has had a profound impact on the field of high-energy physics. First, it provided strong experimental evidence for the quark model, which was an important theory in particle physics at the time. The properties of the J/ψ particles are consistent with the predicted quark combination particles, helping scientists to better understand the internal structure and interactions of elementary particles.
In addition, the discovery of J/ψ particles also greatly promoted the development of collider technology. The scientific community realizes that higher-energy and higher-precision colliders can help them explore more unknown particles like J/ψ particles, and thus unlock more secrets about the most fundamental forces and makeup of the universe. This realization has led scientific research institutions and governments to increase investment in high-energy physics research facilities and to plan for the construction of larger-scale positron and electron colliders.
In the years that followed, several research centers around the world began designing and building higher-energy colliders. The design of these new facilities draws on the technical experience of earlier colliders such as SPEAR, but with significant improvements in energy output, particle control and data processing.
The Higgs Particle Factory
In 2014, the Institute of High Energy Physics of the Chinese Academy of Sciences held an important press conference, officially announcing that they planned to build a large-scale positron collider in the next decade or so, called the "Higgs Particle Factory". The 52-kilometre-long underground loop designed by the collider program is a huge project for the global physics community.
The goal of the project is clear, mainly focused on exploring the properties of the Higgs particle. Since the European Center for Nuclear Research (CERN) first discovered the Higgs particle in 2012 with the Large Hadron Collider (LHC), scientists have been hoping to reveal more about the Higgs field and the origin of the particle's mass through further experiments. However, due to the technical limitations of existing facilities, the exploration of many properties of the Higgs particle is still in its infancy. The Chinese project aims to further advance research in this area through higher-precision, higher-energy collisions.
The launch of this project has received international support from many parties. A number of international scientific research institutions, including scientists and research institutions from Europe, United States, Japan and other places, have expressed their willingness to participate in cooperation.
The planned collider will produce a large number of high-energy particles through the high-speed collision of positrons and negatives, and the trajectory and properties of the secondary particles produced after these collisions will be recorded through a precise experimental setup. Unlike previous colliders, the Higgs Particle Factory was designed for higher energy density and more accurate particle detection capabilities, allowing for more detailed data about the Higgs particles. The data will help scientists gain a deeper understanding of the most fundamental material composition of the universe and how the laws of physics behave at the subatomic scale.
As the initiator and leader of this project, the Institute of High Energy Physics of the Chinese Academy of Sciences has assumed great responsibility. The construction of the collider is not an easy task, from design to construction, to later maintenance and operation, every step is fraught with challenges. In particular, the construction of such a large-scale underground annular collider requires sophisticated engineering techniques and sophisticated control systems to ensure the stability of the particle beam and the accuracy of the collision experiments. In addition, the sheer size of the project means that hundreds of billions of dollars will be invested.
Controversy in academia
However, since the announcement of this project, it has sparked extensive discussion and controversy in the academic community. One of the most prominent figures in this controversy is the famous physicist Yang Zhenning, who has publicly expressed his opposition to the construction of a large particle collider. Yang pointed out that although the scientific significance of building a large collider may be great, the current scientific goals are not clear. Without clear and concrete research goals, the investment of large sums of money can turn into an expensive venture.
Yang's objections focus on several aspects. First, he argues that while the discovery of the Higgs particle has brought great progress to physics, it may not be as simple as initially thought to continue to explore more of the physics behind it. In the absence of specific research directions, tens of billions of yuan of investment faces huge uncertainties. Yang worries that if the project does not lead to the expected scientific breakthroughs, the huge amount of money could become a sunk cost, wasting resources that could have been used for other, more real-world scientific and social projects.
China has made great progress in the field of science and technology in recent years, but there are still many technical links that rely on foreign technical support when building such complex large-scale scientific equipment, especially in superconducting magnets, particle acceleration technology, detector manufacturing, etc. If imports and foreign technical cooperation are still needed in these core areas, there may be no small risks to the autonomy and long-term sustainability of the project.
Yang further pointed out that China's needs in the fields of healthcare, education and life sciences are more urgent. China has a huge population base, and with the development of social economy, medical health, basic education and life science research have become key areas of general concern in society. In his view, if huge amounts of money can be invested in these important areas related to people's livelihood, it will produce more direct and significant social benefits.
These views of Yang Zhenning have sparked extensive discussions in academic circles at home and abroad. Proponents of his view argue that he is more pragmatic and focuses on the rational allocation of resources and return on investment, especially in the face of increasing global economic uncertainty, and should be more cautious about such a large research project. In addition, some opponents also mentioned that although the importance of high-energy physics research is undeniable, its practical application value in the short term is relatively limited, especially in the process of transforming basic research results into practical application technology, the time span may be very long.
The Future of High Energy Physics in China
In stark contrast to Yang's view is Wang Yifang, an academician of the Chinese Academy of Sciences, and his team, who are adamant that China should not only build its own large collider, but also move quickly to seize a position at the forefront of global science and technology. Academician Wang Yifang has repeatedly stated publicly that the construction of a large collider is crucial to China's high-energy physics research.
Wang Yifang's plan to build the collider is divided into two phases: first, the Positron Collider will be built between 2020 and 2030, which will be a device similar to the European Large Hadron Collider, but different in design. The Positron Collider is able to measure the properties of the Higgs particle with extreme precision and delve into fundamental questions of particle physics.
His second-phase plan is more ambitious, with three-quarters of the Proton Collider expected to be completed between 2040 and 2050. The proton collider, which has much higher energy than the positron collider, will be able to delve deeper into higher energy physical phenomena and perhaps even discover new elementary particles or reveal unsolved mysteries in existing theories. Wang Yifang believes that it is precisely because of the potential of these high-energy collision experiments that China must seize this opportunity, otherwise it may lose an important international voice in the field of high-energy physics in the coming decades.
In addition, Academician Wang Yifang and his supporters stressed that although the construction of the Large Collider requires huge financial and technical investment, in the long run, the scientific value of this project far outweighs its cost.
If China is unable to complete the construction of the electron-positron collider between 2020 and 2030, future physics discoveries may be dominated by other countries, especially European and United States. This will deprive China of the opportunity to become a global research center for high-energy physics in the coming decades, and thus lose its international influence and scientific and technological competitiveness in this field. Therefore, China must seize this historic opportunity. In 2024, the China Particle Collider project was officially launched.
References:[1]Wang Chengtao,Xu Qingjin. Superconducting magnet technology on particle collider[J].Science 24h,2020(10):14-17