BBC News - Scientists have hailed a successful switch-on for an enormous experiment which will recreate the conditions a few moments after the Big Bang.
They have now fired two beams of particles called protons around the 27km-long tunnel which houses the Large Hadron Collider (LHC).
The £5bn machine on the Swiss-French border is designed to smash protons together with cataclysmic force.Scientists hope it will shed light on fundamental questions in physics.
But there are great concerns about the safety of these experiments. Wikipedia summarizes some of these concerns.
Concerns have been raised in the media, on the Internet and through the law courts about the safety of the particle physics experiments planned to take place at the Large Hadron Collider (LHC), the world's largest and most powerful particle accelerator to date, built by the European Organization for Nuclear Research (CERN) near Geneva, in Switzerland. The claimed dangers of the LHC particle collisions, which are scheduled to begin on 21 October 2008, include doomsday scenarios involving the production of stable micro black holes and the creation of hypothetical particles called strangelets. To address such concerns, CERN mandated a group of independent scientists to review these scenarios. In a report issued in 2003, they concluded that, like current particle experiments such as the Relativistic Heavy Ion Collider (RHIC), the LHC particle collisions pose no conceivable threat. A second review of the evidence commissioned by CERN was released in 2008. The report, prepared by a group of physicists not involved in the LHC experiments, reaffirmed the safety of the LHC collisions in light of further research conducted since the 2003 assessment. It was reviewed and endorsed by a CERN committee of 20 external scientists and by the Executive Committee of the Division of Particles & Fields of the American Physical Society, and was later published in the peer-reviewed Journal of Physics G. The report concludes that any doomsday scenarios at the LHC are ruled out because the physical conditions and events that will be created in the LHC experiments occur naturally in the universe without hazardous consequences.
Should we be worried?
Addition: I should clarify that I am not afraid and find the whole thing fascinating.