Officials at Cern, home of the Large Hadron Collider near Geneva, is pressing ahead with plans for a new machine that will be at least three times larger than the existing particle accelerator.
The Large Hadron Collider, built in a 27km circular tunnel beneath the Swiss-French countryside, collides protons and other subatomic particles at close to the speed of light to recreate the conditions that existed fractions of a second after the Big Bang have.
The machine, the world’s biggest collider, discovered the Higgs boson in 2012, almost 50 years after it was proposed by Peter Higgs, the theoretical physicist at the University of Edinburgh, and several other researchers. The achievement was honored with the Nobel Prize in Physics the following year.
But since the discovery of the Higgs bosonthe collider did not reveal any significant new physics that would shed light on some of the deepest mysteries of the universe, such as the nature of dark matter or dark energy, why matter dominates antimatter, and whether reality is permeated with hidden extra dimensions.
Cern plans for the next machine drawn up, the Future Circular Collider (FCC), in 2019. The €20bn (£17bn) machine will have a 90-100km circumference and aim to smash together subatomic particles at a maximum energy of 100 tera electron volts (TeV ). The Large Hadron Collider reaches maximum energies of 14TeV.
However, the proposal has its critics. Sir David King, the UK’s former government chief science adviser, told the BBC that spending billions on the machine would “reckless” when the world was facing such serious threats from the climate crisis.
On Friday the Cern The board discussed an interim review of a feasibility study for the FCC. If the plans go ahead, the organization will seek approval in the next five years and hopes to have the machine built and ready for operations in the 2040s when the LHC completes its runs.
Prof Fabiola Gianotti, the director general of Cern, told the Guardian: “If approved, the FCC will be the most powerful microscope ever built to study the laws of nature at the smallest scales and highest energies, with the aim to some of the outstanding questions in today’s fundamental physics and our understanding of the universe.”
“The scientific case is really exciting,” says Tara Shears, a member of the LHCb experiment at the Large Hadron Collider, and professor of physics at the University of Liverpool. “At the moment we are doing a study to see if the machine is feasible. This should be completed in 2025, with a decision on the best way forward by 2028.
“This is a next-generation machine: bigger, faster, stronger, with the ability to reveal so much more detail about the fine details of the universe. It will reveal features of the Higgs and Higgs field that just can’t be studied at the Large Hadron Collider, and let us search for dark matter and test new physics ideas in new regimes.”
If the machine is approved, it will be built in two phases. The first experiments would collide electrons while the second phase, earmarked for the 2070s, would bump protons into each other. Because of the extra radiation generated by the machine, it will have to sit twice as far underground as the Large Hadron Collider.
Dr Sabine Hossenfelder, at the Frankfurt Institute for Advanced Studies, is critical of the plans and says there is no evidence that the FCC would reveal anything about dark matter or dark energy.
“The truth is that the most likely thing such a machine will do is just make better measurements of some constants in the standard model, and that’s it,” she said. “I don’t think the social relevance is high enough to justify such a large investment.”
“I fear that funding such an experiment will mean that very smart people will waste their time on research that will not lead to any progress. The LHC had a good motivation. The FCC did not. Particle physicists must accept that their time is over. This is the age of quantum physics.”
Prof Jon Butterworth, a member of the Atlas experiment at the Large Hadron Collider and a professor of physics at University College London, said the collider was a work in progress.
“It’s about extending the frontier of human knowledge to the heart of matter and the fundamental forces, partly to see how fundamental they really are,” he added.
