One problem is that society has never agreed on a standard of what is safe in these surreal realms when the odds of disaster might be tiny but the stakes are cosmically high. In such situations, probability estimates are often no more than “informed betting odds,” said Martin Rees, a Cambridge University cosmologist, the astronomer royal and the author of “Our Final Hour.” Adrian Kent, also of Cambridge, said in a paper in 2003 reviewing scientists’ failure to calculate adequately and characterize accurately risks to the public, that even the most basic question, “ ‘How improbable does a catastrophe have to be to justify proceeding with an experiment?’ seems never to have been seriously examined.”

Dr. Calogero commented, as did Dr. Kent, in 2000 after a very public battle on the safety of another accelerator, the Relativistic Heavy Ion Collider, or Rhic, at the Brookhaven National Laboratory on Long Island. Dr. Calogero said he hoped to apply a gentle pressure on Cern to treat these issues with seriousness. “A crusade against it is a danger,” he said of the new collider. “It would not be based on rational argument.”

Image Credit... Harry Campbell

Fears about the Brookhaven collider first centered on black holes but soon shifted to the danger posed by weird hypothetical particles, strangelets, that critics said could transform the Earth almost instantly into a dead, dense lump. Ultimately, independent studies by two groups of physicists calculated that the chances of this catastrophe were negligible, based on astronomical evidence and assumptions about the physics of the strangelets. One report put the odds of a strangelet disaster at less than one in 50 million, less than a chance of winning some lottery jackpots. Dr. Kent, in a 2003 paper, used the standard insurance company method to calculate expected losses to explore how stringent this bound on danger was. He multiplied the disaster probability times the cost, in this case the loss of the global population, six billion. A result was that, in actuarial terms, the Rhic collider could kill up to 120 people in a decade of operation.

“Put this way, the bound seems far from adequately reassuring,” Dr. Kent wrote.

Alvaro de Rujula of Cern, who was involved in writing a safety report, said extending the insurance formula that way violated common sense. “Applied to all imaginable catastrophes, it would result in World Paralysis,” he wrote.

Besides, the random nature of quantum physics means that there is always a minuscule, but nonzero, chance of anything occurring, including that the new collider could spit out man-eating dragons.

Doomsday from particle physics is part of the culture.

Next year will see the release of the film version of “Angels and Demons,” the prequel to Dan Brown’s “DaVinci Code,” in which the bad guys use a Cern accelerator to gather antimatter for a bomb to blow up the Vatican, and it includes scenes at Cern.