China can build the largest collider on Earth, CERN president says

Eliezer Rabinovici says he is ‘confident’ Chinese scientists can build the world’s largest particle accelerator
The proposed Circular Electron Positron Collider has caused much debate in China over whether it justifies the US$5 billion cost

Science

Dannie Peng

Published: 1:21pm, 6 May 2024

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One of Israel’s top physicists has entered the debate over whether China should build the world’s largest collider, saying he believes the country is now capable of the feat.

Eliezer Rabinovici, an emeritus professor of physics at the Hebrew University of Jerusalem who is also the president of the European Organisation for Nuclear Research (CERN), said during a visit to China in early April: “Chinese scientists can build this machine.”

CERN operates the world’s biggest and most powerful particle accelerator, the Large Hadron Collider (LHC), housed in a ring-shaped tunnel 27km (16.8 miles) in circumference beneath the Swiss-French border.

China’s proposed 36 billion yuan (US$5 billion) Circular Electron Positron Collider (CEPC), also known as a Higgs factory, would dwarf the LHC with a circumference of 100km.

The Chinese government has not given the final approval to the project, which has sparked widespread debate in China among the scientific community and the general public.

The strongest opposition has come from legendary physicist and Nobel laureate Yang Chen-ning.

Yang, who denounced his US citizenship and now lives in Beijing, has previously questioned the need to build a super collider, saying in 2016 that it was “not for today’s China” as the country had more acute needs to deal with, such as economic development and environmental protection.

Rabinovici said he had read what Yang said and the reactions of Chinese scientists at the time, but he believed that Yang, like many others, “underestimated the capability that exists here in China”.

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The CERN president, whose work focuses on theoretical high-energy physics, said during his visit that he had seen tremendous progress in Chinese science, with the country boasting a strong talent pool.

“Over the years, many Chinese physicists have worked at CERN and have gained some knowledge and experience. These people are very capable,” Rabinovici said.

For example, Wang Yifang, the mastermind behind the CEPC project, once worked at CERN with Nobel Prize winner Samuel Chao Chung Ting after graduating from Nanjing University with a bachelor’s degree in physics in 1984.

CERN is now considering expanding the LHC into a machine nearly 100km long, and Rabinovici was invited by the Institute of High Energy Physics (IHEP) in Beijing to share some thoughts and plans for the new project.

What he found during his trip was that Chinese scientists are putting enormous effort into tackling some of the CEPC’s toughest challenges, such as energy conservation.

“Their approach to the challenges is not much different from CERN’s, so I am confident that Chinese scientists can do it,” he said.

The question of whether China should build the world’s largest collider has been debated in China for nearly a decade.

Wang, director of IHEP, first proposed the idea of building the CEPC in 2012 after the Higgs boson – the “God particle” that gives mass to almost all other particles – was discovered in Europe using the LHC.

By accelerating electrons and their antiparticles – positrons – to extremely high energies and smashing them into each other, the infrastructure will create millions of Higgs bosons and allow scientists to make new discoveries beyond the Standard Model – the best theory so far describing the basic building blocks of the universe.

Chinese scientist and Nobel laureate Yang Chen-ning has said the money needed to build the proposed collider would be a “bottomless pit”. Photo: VCG via Getty Images

“I think there’s no doubt that tens of thousands of scientists from all over the world, including the United States, Europe and China, strongly believe that this is a good project that is worth doing,” Rabinovici said.

A physicist at a top mainland university, who declined to be named because he is not authorised to speak to the media, said the team led by Wang was made up of outstanding scientists.

Over the past decade, he said, their research had been highly regarded by international physicists, and the CEPC project they were designing was attracting huge global attention.

The physicist also “strongly disagrees” with Yang’s argument that investing in a huge project like this would squeeze funding for other urgent social issues and other areas of science.

He did not think that China lacked the money for such a project. The problem was how to spend scientific funds wisely, he said, and he believed the amount of money that was wasted on various projects could already be considerable.

In response to the financial burden of the project, which Yang previously warned was a “bottomless pit”, Wang recently admitted that “36 billion yuan is not cheap”.

However, in the interview with the Global Times in March, Wang pointed out that if the CEPC could support the work of thousands of scientists for decades to come, the average cost would not be that high.

Wang told the Global Times that construction of this super collider in China could begin in three years’ time, although it still needed to secure government approval and funding.

Wang added that the CEPC’s “technical design report” – which took more than 1,000 scientists from 24 countries five years to compile – had passed an international review and received “overwhelming feedback” from the physics community when it was released in December.