"Five, four, three, two, one... nothing," Dr Evans said, in a nervous attempt at humour. The reputation of European science hung by a thread for nearly four minutes, until at last the computer screen at the control centre said something had happened. There was a round of applause from everyone present.
"It's not like trying to start your home computer," the press relations woman said later. "It's much, much more complicated."
One small indicator of the uniqueness of the occasion was that Cern staff abandoned the usual standards of scruffiness associated with advanced science. Dr Evans, a miner's son from south Wales, was dressed in a shirt and jeans. His normal work clothes are a T-shirt and shorts.
The glitch was caused by a cryogenic problem, cryogenics being the science of producing low temperatures. The temperature inside the Large Hadron Collider (LHC), the particle accelerator built by Cern, is about as close to absolute zero as it is possible to get. It is colder than outer space. Around its 27km underground tunnel there are 6,500 magnets, with enough power to cause protons fired into the LHC to accelerate to more than 99.99 per cent of the speed of light. If one of those thousands of magnets is 1C warmer than it should be, or 1mm out of position, it could wreck the experiment.
Engineers discovered on Monday night that there was something wrong, and worked frantically to put it right. The night shift on Tuesday discovered more problems. But when the scientists assembled at 9am yesterday, they were briefed that all was now OK. Then came those four doom-laden moments, when it looked as if something else had gone horribly wrong.