“CERN Makes Bold Push to Build €21-Billion Supercollider: European Particle-Physics Lab Will Pursue a 100-Kilometre Machine to Uncover the Higgs Boson’s Secrets—But It Doesn’t yet Have the Funds”, 2020-06-19 (; backlinks):
CERN has taken a major step towards building a 100-kilometer circular supercollider to push the frontier of high-energy physics.
The decision was unanimously endorsed by the CERN Council, the organization’s governing body, on 19 June, following the plan’s approval by an independent panel in March. Europe’s pre-eminent particle-physics organization will need global help to fund the project, which is expected to cost at least €21 billion (US$24 billion) and would be a follow-up to the lab’s famed Large Hadron Collider (LHC). The new machine would be colliding electrons with their antimatter partners, positrons, by the middle of the century. The design—to be built in an underground tunnel near CERN’s location near Geneva, Switzerland—will enable physicists to study the properties of the Higgs boson and, later, to host an even more-powerful machine that will collide protons and will last well into the second half of the century.
…Funding Tour: CERN’s strategy envisages 2038 as the date for beginning construction of the new, 100-kilometer tunnel and the electron-positron collider. Until then, the lab will continue to operate an upgraded version of the LHC, called High Luminosity LHC, which is currently under construction. But before CERN can start building its new machine, it will have to seek new funding beyond the regular budget it receives from member states. Llewellyn Smith says that countries outside Europe, including the United States, China and Japan, might need to join CERN to form a new, global organization. “Almost certainly it will need a new structure”, he says.
The costly plan has its detractors—even in the physics community. Sabine Hossenfelder, a theoretical physicist at the Frankfurt Institute for Advanced Studies in Germany, has emerged as a critic of pursuing ever-higher energies, when the scientific payback—apart from measuring the properties of known particles—is far from guaranteed. “I still think it’s not a good idea”, Hossenfelder says. “We’re talking about tens of billions. I just think there is not enough scientific potential in doing that kind of study right now.”
The new collider will be in uncharted territory, says Tara Shears, a physicist at the University of Liverpool, UK. The LHC had a clear target to look for—the Higgs boson—as well as theorists’ well-motivated reasons to believe that there could be new particles in the range of masses it could explore, but the situation now is different, she says. “We don’t have an equivalent, rock-solid prediction now—and that makes knowing where and how to look for answers more challenging and higher risk.” Still, she says, “We do know that the only way to find answers is by experiment and the only place to find them is where we haven’t been able to look yet.”