What is the Future Circular Collider?
The Future Circular Collider (FCC) is a proposed next-generation particle accelerator being studied by CERN as a possible successor to the Large Hadron Collider (LHC).
The preferred design envisages an underground circular tunnel of about 90.7 km circumference, much larger than the 27 km LHC.
The proposed tunnel would run beneath parts of:
- France;
- Switzerland;
- the Lake Geneva region.
Its objective is to push particle physics beyond the capabilities of the LHC and investigate fundamental questions that remain unanswered by the Standard Model of particle physics.
The FCC is not yet approved for construction. As of 2026, it remains under technical, financial, environmental and political assessment, with a construction decision expected around 2028.
Two-Stage Scientific Programme
The FCC is conceived as a long-term programme with two major stages.
FCC-ee
The first stage would be an electron-positron collider.
It would operate as an extremely precise Higgs factory, producing large numbers of Higgs bosons and other particles under comparatively clean experimental conditions.
Its major scientific objectives include precision measurements of:
- Higgs boson properties;
- W and Z bosons;
- top quark;
- electroweak interactions.
Electron-positron collisions are particularly valuable for precision physics because electrons are elementary particles, producing cleaner collision environments than proton collisions.
The FCC-ee could therefore reveal very small deviations from Standard Model predictions, potentially providing indirect evidence of new physics.
FCC-hh
At a later stage, the same tunnel could host a much more powerful proton-proton collider.
The proposed FCC-hh could reach collision energies of up to approximately 100 teraelectronvolts (TeV), compared with roughly 14 TeV design collision energy for the LHC.
Its much higher energy would allow physicists to search directly for particles and phenomena that may be inaccessible to existing accelerators.
Why is a New Collider Needed?
The LHC achieved one of modern physics’ greatest breakthroughs with the discovery of the Higgs boson in 2012.
However, the Standard Model remains incomplete.
It does not satisfactorily explain:
- dark matter;
- dark energy;
- why matter dominates antimatter;
- neutrino masses;
- gravity within a quantum framework;
- the large hierarchy between fundamental physical scales.
No confirmed new elementary particle beyond the Standard Model has yet emerged from LHC observations.
The FCC therefore follows a two-pronged strategy:
- precision frontier through FCC-ee, looking for tiny deviations from known physics;
- energy frontier through FCC-hh, directly probing much higher energy scales.
It could also greatly improve understanding of the Higgs field, which is central to explaining how elementary particles acquire mass.
FCC vs Large Hadron Collider
The FCC would represent a major scale-up from the LHC.
Large Hadron Collider
- circumference: about 27 km;
- located at CERN near Geneva;
- proton-proton collider, with other ion operations;
- discovered the Higgs boson;
- being upgraded into the High-Luminosity LHC.
Future Circular Collider
- proposed circumference: about 91 km;
- initially electron-positron;
- later potentially proton-proton;
- FCC-hh energy potentially around 100 TeV;
- designed for both precision measurements and discovery of new physics.
The FCC would therefore not simply be a larger LHC. It is conceived as a multi-decade research infrastructure hosting different collider technologies sequentially.
Latest Status and Major Challenges
CERN completed its major FCC Feasibility Study in March 2025.
The preferred configuration includes:
- a 90.7 km tunnel;
- average depth of roughly 200 metres;
- eight surface access sites;
- provision for four major experiments.
Independent technical reviews found no fundamental technical “showstopper”, but major issues remain.
These include:
- enormous construction and operating cost;
- securing international financial participation;
- geological and engineering complexity;
- environmental impacts;
- excavation and reuse of millions of tonnes of material;
- electricity and resource requirements;
- territorial approval from France and Switzerland;
- long construction and technological-development timelines.
In May 2026, the CERN Council updated the European Strategy for Particle Physics, providing the strategic framework within which the next flagship collider will be considered.
Public consultation processes are also underway in France and Switzerland during 2026.
If eventually approved, preparatory and civil-engineering work would extend through the 2030s, with the FCC potentially beginning operation in the mid-to-late 2040s.
Wider Significance
The FCC is important beyond particle physics.
Large accelerator projects drive advances in:
- superconducting magnets;
- cryogenics;
- vacuum technology;
- artificial intelligence and big-data processing;
- high-performance computing;
- medical accelerator technologies;
- advanced materials;
- precision instrumentation.
The project also raises an important science-policy debate.
Supporters argue that fundamental research frequently produces transformative technologies while addressing some of the deepest questions about the Universe.
Critics question whether the very high financial and environmental cost of a mega-collider is justified when there is no guarantee that entirely new particles will be discovered.
The Future Circular Collider therefore represents both a scientific project and a major global policy choice about the future direction, scale and financing of fundamental physics after the LHC era.
