By Geoff Brumfiel
The end of the world is not nigh after all. Flouting predictions from some theorists, microscopic black holes have so far failed to appear inside the Large Hadron Collider (LHC), scientists there have revealed.
The result, which will be posted this week on arXiv.org, comes as researchers make plans to keep the LHC running until the end of 2012, rather than 2011 as previously scheduled. The 27-kilometre collider at the particle-physics laboratory CERN near Geneva, Switzerland, had endured delays and a crippling breakdown before finally surging to life late in 2009, and physicists say it is now performing above expectations.
Predictions of mini black holes forming at collision energies of a few teraelectronvolts (TeV) were based on theories that consider the gravitational effects of extra dimensions of space. Although the holes were expected to evaporate quickly, some suggested that they might linger long enough to consume the planet. But scientists at the Compact Muon Solenoid (CMS) detector now say they found no signs of mini black holes at energies of 3.5-4.5 TeV. Physicist Guido Tonelli, the detector's spokesperson, says that by the end of the next run, the LHC should be able to exclude the creation of black holes almost entirely.
The find is one of a stream of recent papers from the LHC, made possible by the machine's unexpectedly high performance. "We were very surprised by how well behaved the machine was when we started really pushing it to its limit," says Steve Myers, the CERN physicist who oversaw this year's LHC operations. As a consequence, physicists are increasingly optimistic that they may be able to detect the elusive Higgs boson earlier than expected. The particle, the LHC's best-known quarry, and its associated field are thought to endow other particles with mass.
Initially, physicists were not sure that the LHC could create and detect the Higgs at the machine's current energies, and CERN managers had planned a 15-month hiatus from the start of 2012 for an upgrade that would allow it to run at higher energies. But a growing consensus holds that even without the upgrade, the LHC will be able to explore most of the energy range in which a standard Higgs particle might be found. Sergio Bertolucci, CERN's director for research and computing, adds that there are political reasons to extend the run. The world's second most powerful accelerator, the Tevatron at Fermilab in Batavia, Illinois, is nipping at the LHC's heels as it gathers a growing body of data in its own Higgs hunt. Moreover, the potential success of the LHC is likely to influence European plans for high-energy physics, as well as a global plan for a next-generation linear collider. Both face big budget decisions in the next few years.
The plan to extend the LHC's run will be discussed at a meeting of LHC managers in Chamonix, France, in late January, with a final decision expected shortly after.