Hackers say they've broken into one of the computer networks of the Large Hadron Collider (LHC).

A group calling itself the Greek Security Team left a rogue Web site describing the technicians responsible for computer security at the giant atom smasher as "schoolkids" — but reassuring scientists that they did not want to disrupt the experiment.

The hackers gained access to a Web site open to other scientists on Wednesday as the LHC passed its first test, sending its protons off on their dizzying journey through time and space, close to the speed of light.

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The work of the scientists was not derailed and insiders scoffed at claims that the hackers were "one step away" from the systems controlling the experiment itself. The engineering team completed four days of scheduled work in the first 24 hours but what physicists are really waiting for is the big bang machine's first collisions.

Apart from being wide of the mark from a scientific point of view, fears that the LHC might bring the world to an end this week were in any case premature because it was never going to smash any particles so early on.

This week's successful start-up means that should happen sooner than expected, perhaps as early as the first week in October.

The hackers appear to have targeted the computer system of the Compact Muon Solenoid Experiment, one of the four detectors that will be analyzing the progress of the experiment.

"We don't know who they were but there seems to be no harm done," said James Gillies, a spokesman for CERN, the European Laboratory for Network Collision, and home of the LHC. "It appears to be people who want to make a point that CERN was hackable."

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