CERN’s Future Circular Collider Plans

The scientific community is currently engaged in a high-stakes discussion regarding the future of particle physics. At the center of this conversation is the Future Circular Collider (FCC), a proposed machine that would dwarf the current Large Hadron Collider (LHC). With a projected cost of roughly $17 billion (15 billion Swiss Francs) and a timeline stretching late into the 21st century, this project represents one of the most ambitious and expensive scientific undertakings in human history.

The Massive Scale of the FCC

To understand the magnitude of the FCC, you have to look at what currently exists. The Large Hadron Collider (LHC), situated beneath the France-Switzerland border near Geneva, has a circumference of 27 kilometers (17 miles). It is currently the world’s largest and most powerful particle accelerator.

The proposed FCC would be a subterranean ring with a circumference of approximately 91 kilometers (56 miles). It would encircle Geneva and extend well into the French countryside, passing under Lake Geneva.

A Two-Stage Strategy

CERN does not plan to build the ultimate machine immediately. The proposal outlines a two-stage integrated program:

  1. FCC-ee (The Higgs Factory): Scheduled to begin operations around 2045, this phase involves an electron-positron collider. Its primary mission is to produce huge quantities of Higgs bosons. Scientists want to measure the properties of this particle with extreme precision to understand how matter obtains mass.
  2. FCC-hh (The Energy Frontier): Once the FCC-ee program concludes (around 2060), the tunnel would be repurposed. Engineers would install powerful superconducting magnets to create a proton-proton collider. This machine would target an energy level of 100 tera-electronvolts (TeV), compared to the LHC’s current maximum of 13.6 TeV. Operations for this phase would likely begin in the 2070s.

The $17 Billion Debate

The primary point of contention is the price tag. The initial construction cost is estimated at 15 billion Swiss Francs. This amount covers the construction of the tunnel and the first machine (FCC-ee). The second phase (FCC-hh) would require an additional investment, potentially bringing the total cost even higher over the project’s lifespan.

The Argument for Construction

Proponents, including CERN Director-General Fabiola Gianotti, argue that the FCC is the only logical step forward for high-energy physics. Their arguments rest on several pillars:

  • Dark Matter: The Standard Model of particle physics describes visible matter, but this accounts for only 5% of the universe. The rest is Dark Energy and Dark Matter. The LHC has not yet identified particles responsible for Dark Matter. A more powerful collider increases the chances of spotting these elusive components.
  • The Higgs Boson: While the LHC discovered the Higgs boson in 2012, it produces them relatively rarely. The FCC-ee would generate millions of them, allowing for “precision physics” that could reveal cracks in our current understanding of the universe.
  • Technological Spinoffs: Supporters point out that CERN research leads to practical applications, such as the World Wide Web and advancements in medical imaging (PET scans) and cancer therapy.

The Argument Against

Critics, such as theoretical physicist Dr. Sabine Hossenfelder, argue that the project is a gamble with poor odds. The criticism focuses on:

  • Lack of Guarantees: The LHC did not find “supersymmetry” (SUSY), a theory many physicists hoped to confirm. Critics argue there is no theoretical guarantee that a 100 TeV collider will discover new particles. It might simply confirm existing theories with slightly higher precision.
  • Opportunity Cost: $17 billion is a massive sum. Detractors argue these funds could be better spent on other scientific endeavors, such as climate change research, pandemic preparedness, or smaller, more diverse physics experiments (like radio astronomy or tabletop quantum gravity experiments).
  • Diminishing Returns: Science has moved past the “low-hanging fruit.” Discovering the next particle might require energy levels even the FCC cannot reach, leading to a “desert” where no new physics is observed regardless of the machine’s size.

Engineering and Geological Challenges

Building a 91-kilometer tunnel is not just a financial issue; it is a geological one. The tunnel must be dug through the Molasse basin, avoiding the limestone of the Jura mountains to prevent water ingress and high pressure.

CERN is currently conducting a Feasibility Study, which is expected to be completed in 2025. This study includes:

  • Geological Drilling: Engineers are drilling boreholes to analyze the rock stability under the specific areas of France and Switzerland where the tunnel would sit.
  • Environmental Impact: The project requires significant surface sites for cooling towers, ventilation, and access shafts. CERN has committed to minimizing the environmental footprint, but local opposition in the Geneva and Haute-Savoie regions remains a hurdle.
  • Power Consumption: The FCC would require roughly 1.8 terawatt-hours of electricity per year. This is equivalent to the annual consumption of a modest regional transport network. CERN is investigating ways to make the facility energy-efficient and potentially use waste heat to warm nearby residential areas.

The Decision Timeline

The project is currently in the investigation phase. The roadmap looks like this:

  • 2025: Completion of the Feasibility Study.
  • 2028: The CERN Council (representing the member states) must make a final decision on whether to approve the project.
  • 2033: If approved, tunnel excavation would begin.
  • 2045-2048: The FCC-ee (electron-positron) machine begins collecting data.

If the member states—which include Germany, the UK, France, and Italy—balk at the cost, the project may be scrapped or significantly altered. Alternatively, high-energy physics leadership could shift to China, which is proposing its own Circular Electron Positron Collider (CEPC) with a similar design and timeline.

Frequently Asked Questions

Why can’t they just upgrade the LHC again? The LHC is already being upgraded to the “High-Luminosity LHC” (HL-LHC), which will operate until roughly 2041. However, the LHC is limited by its size. To reach higher energy levels, you need either stronger magnets or a larger ring. The 27km tunnel physically restricts how much energy can be generated, regardless of magnet technology.

Who pays for the FCC? CERN is funded by its 23 Member States. Each country contributes in proportion to its Net National Income. Germany, the UK, France, and Italy are the largest contributors. Additionally, non-member Associate States (like India and Ukraine) and Observer States (like the USA and Japan) may contribute to specific projects.

Will the FCC create a black hole that destroys Earth? No. This was a fear during the launch of the LHC as well. Cosmic rays hit the Earth’s atmosphere every day with far higher energies than the FCC will produce. If these collisions could create dangerous black holes, the Earth would have been destroyed billions of years ago.

Is China building a similar collider? Yes. China has proposed the Circular Electron Positron Collider (CEPC). It would also be a 100km ring and serves as a direct competitor to CERN’s plan. If China proceeds faster, it could claim the title of the world’s leading center for particle physics.