Too expensive even for China : the country halts its ambitious race with Europe to build the world’s largest particle accelerator

17 December 2025

In the rarefied world of high-energy physics, ambition is measured in kilometres and budgets in billions of pounds. For years, a silent but intense race was underway between China and Europe to build the next great scientific instrument: a particle accelerator that would dwarf all predecessors. This machine, a successor to the famed Large Hadron Collider, promised to unlock the deepest secrets of the universe. Yet, this grand scientific marathon has seen a surprising development, with one of the main contenders pulling up short, revealing that even for a global superpower, some ambitions come with a price tag too high to bear.

The race for accelerators: a challenge between China and Europe

China’s proposed supercollider

China threw down the gauntlet with its proposal for the Circular Electron Positron Collider (CEPC). This was not merely an upgrade or a next-generation machine; it was a monumental leap in scale and power. Envisioned as a 100-kilometre-long underground ring, it would be nearly four times the size of the current record holder, the Large Hadron Collider (LHC) at CERN. The primary goal of the CEPC was to be a ‘Higgs factory’, producing millions of Higgs bosons to allow for precision measurements far beyond the capabilities of the LHC. This project was a clear statement of intent, designed to position China as the undisputed global centre for particle physics.

Europe’s counter-proposal

In response, and as part of its long-term strategy, Europe’s particle physics laboratory, CERN, has been developing plans for its own successor to the LHC. The Future Circular Collider (FCC) is a similarly ambitious project, also proposing a tunnel of around 100 kilometres. The European plan is a staged approach, beginning with an electron-positron collider (FCC-ee), much like the CEPC, before potentially upgrading to a proton-proton collider (FCC-hh) capable of reaching unprecedented energy levels. The competition was clear: two scientific heavyweights vying to build the world’s next great discovery machine.

Collider Project Comparison

Feature	Chinese CEPC	CERN’s FCC (conceptual)	CERN’s LHC (current)
Circumference	~100 km	~91 km	27 km
Primary Goal (Phase 1)	Higgs Factory (e+e-)	Higgs/Z/W Factory (e+e-)	Higgs Discovery (p-p)
Projected Initial Cost	~ £5 billion	~ £10 billion (for e+e- phase)	~ £4 billion (initial construction)
Status	Halted / Indefinitely Postponed	Under review and design study	Operational

The stark contrast in scale and cost highlighted the monumental challenge both sides were undertaking. However, the initial fervour behind the Chinese project would soon face the harsh realities of national priorities and economic constraints, putting its ambitious timeline and very existence into question.

The Chinese ambitions put to the test

A project of unprecedented scale

The sheer magnitude of the CEPC project cannot be overstated. Beyond its 100-kilometre circumference, the plan involved a multi-decade commitment, culminating in a potential upgrade to a Super Proton-Proton Collider (SppC) in the same tunnel. This future machine would have reached collision energies seven times greater than the LHC. The project’s proponents argued it would attract the world’s top scientific talent to China, fostering innovation and cementing the nation’s reputation as a leader in fundamental research. The goals were clear and compelling:

To precisely measure the properties of the Higgs boson, the particle that gives mass to other fundamental particles.
To search for physics beyond the Standard Model, including evidence of supersymmetry or dark matter.
To establish a long-term roadmap for high-energy physics, driven and hosted by China.

This was more than a scientific instrument; it was envisioned as a cornerstone of China’s scientific ascendancy for the 21st century.

Internal dissent and scientific debate

Despite the grand vision, the project was not without its critics within China’s own scientific community. The most prominent opponent was the Nobel laureate physicist Yang Chen-ning. He argued forcefully that the project was a colossal waste of money. He believed the enormous investment would divert critical funding from other more pressing scientific fields like materials science and life sciences, which he saw as offering more immediate and tangible benefits to the country. Yang argued that the scientific returns of a new collider were speculative, whereas the cost was concrete and astronomical. This high-profile dissent created a significant rift in the community, forcing a national debate on the value of ‘blue-sky’ research versus applied science. The project’s momentum was undeniably slowed by these powerful internal arguments.

Economic factors: a major hindrance for China

The prohibitive cost of fundamental science

Ultimately, the most significant obstacle for the CEPC was its staggering price tag. Initial estimates placed the cost of the first phase at around £5 billion, but many physicists believed this was a conservative figure, with the final cost likely to be much higher. As China’s economy began to face headwinds, with slowing growth and shifting priorities towards technological self-sufficiency in areas like semiconductors, justifying such a colossal expenditure on fundamental physics became increasingly difficult. The government had to weigh the potential, long-term prestige of a supercollider against more immediate strategic and economic needs. This financial reality cast a long shadow over the project’s viability.

Shifting national priorities

The decision to halt the project reflects a broader shift in Beijing’s strategic thinking. While scientific leadership remains a goal, the focus has pivoted towards technologies with direct economic and geopolitical applications. The immense resources, both financial and intellectual, required for the CEPC were seen as a diversion from critical national objectives. The leadership seemingly decided that investing billions in smashing particles to perhaps find new ones was a luxury it could not afford when faced with pressing challenges in other technological domains. The opportunity cost was simply deemed too high. This pivot away from mega-projects in fundamental research highlights a pragmatic, if perhaps less visionary, approach to scientific investment, a decision that has profound implications for the global scientific landscape.

The technological and scientific stakes involved

The quest for new physics

The suspension of the CEPC is a significant blow to the global physics community. Machines like the proposed supercolliders are essential tools in the quest to answer some of the most fundamental questions about our universe. The Standard Model of particle physics, while incredibly successful, is known to be incomplete. It does not account for phenomena like:

Dark matter: The invisible substance that makes up about 27% of the universe.
Dark energy: The mysterious force driving the accelerated expansion of the universe.
Neutrino mass: The Standard Model predicts neutrinos should be massless, but experiments have shown they are not.

A Higgs factory like the CEPC would have provided a unique window into these mysteries. By measuring the Higgs boson’s properties with extreme precision, physicists hope to find tiny deviations from the Standard Model’s predictions, which would be the first clues to a new, more complete theory. The loss of this project means these clues may remain hidden for much longer.

Technological spin-offs and innovation

Large-scale scientific projects are powerful engines of technological innovation. The construction of the LHC at CERN, for instance, led to advancements in cryogenics, vacuum technology, data processing, and superconducting magnets. The World Wide Web itself was famously invented at CERN to help scientists share data. The CEPC project was expected to generate similar spin-offs, pushing the boundaries of Chinese industry in high-tech fields. Halting the project means forgoing these potential technological dividends, which often have applications far beyond the realm of pure science. The decision, therefore, represents not just a scientific loss, but a missed opportunity for broader technological development that could have benefited the entire nation.

Europe, leader of particle accelerators ?

CERN’s strengthened position

With China effectively withdrawing from the race, CERN’s position as the world’s pre-eminent centre for high-energy physics is solidified for the foreseeable future. The development of the Future Circular Collider, while still in its planning stages and facing its own significant funding hurdles, now stands as the most credible and advanced plan for a post-LHC machine. The LHC itself is undergoing upgrades to become the High-Luminosity LHC, which will extend its operational life into the 2040s. This gives CERN a clear, uninterrupted roadmap for the next two decades. China’s withdrawal removes a major competitor and potential partner, leaving Europe, for now, as the undisputed flag-bearer for mega-science in particle physics.

The challenges ahead for the FCC

Despite this strengthened position, the path forward for CERN is not without its own challenges. The estimated cost of the FCC is even higher than that of the CEPC, requiring sustained and substantial political and financial commitment from its member states. In a climate of economic uncertainty and competing public priorities across Europe, securing such funding will be a monumental task. The scientific case for the FCC must be made compellingly to politicians and the public alike. The halt of the Chinese project serves as a stark reminder that scientific ambition alone is not enough to bring these colossal machines to life. Europe’s leadership is secure for now, but realising its own future vision will require navigating the same economic and political realities that grounded its rival.

Prospects for global scientific research

The future of international collaboration

The immense cost and complexity of next-generation particle accelerators raise a critical question: can any single nation or region afford to build them alone ? China’s decision suggests that the answer may be no. This could usher in a new era where such mega-projects are only feasible as truly global collaborations, pooling resources, expertise, and funding from multiple continents. An intercontinental project, while politically and logistically complex, would distribute the financial burden and reflect the inherently international nature of scientific discovery. The suspension of the CEPC might inadvertently become the catalyst for a more collaborative, global model for the future of fundamental research.

A potential slowdown in discovery

In the short to medium term, the absence of the CEPC will likely mean a slowdown in the pace of discovery in particle physics. The High-Luminosity LHC will continue to produce valuable data, but it cannot perform the precision measurements that a dedicated Higgs factory could. The insights that the CEPC was designed to provide into the Higgs boson and potential new physics will be delayed by at least a decade, if not more, until the FCC or a similar project is built. This creates a potential ‘gap’ in our ability to probe the energy frontier, a period of waiting for the next great tool. The global scientific community must now recalibrate its expectations and timelines, adapting its research programmes to a world with one less supercollider on the horizon.

The indefinite postponement of China’s supercollider marks a pivotal moment, stemming primarily from its colossal cost and a shift in national priorities towards applied technologies. This development effectively ends the direct race with Europe, cementing CERN’s leadership position with its plans for a Future Circular Collider. The episode serves as a powerful illustration of the immense economic and political challenges facing mega-science, suggesting that the future of such ambitious projects may lie not in national competition, but in broader, global collaboration.