MEYRIN, Switzerland — The most powerful atom- smasher ever built could make some bizarre discoveries, such as invisible matter or extra dimensions in space, after it is switched on in August.
But some critics fear the Large Hadron Collider could exceed physicists’ wildest conjectures: Will it spawn a black hole that could swallow Earth? Or spit out particles that could turn the planet into a hot dead clump?
Ridiculous, say scientists at the European Organization for Nuclear Research, known by its French initials, CERN — some of whom have been working for a generation on the $5.8 billion collider, or LHC.
“Obviously, the world will not end when the LHC switches on,” said project leader Lyn Evans.
The collider basically consists of a ring of supercooled magnets 17 miles in circumference attached to huge barrel-shaped detectors. The ring, which straddles the French and Swiss border, is buried 330 feet underground.
The machine, which has been called the largest scientific experiment in history, isn’t expected to begin test runs until August, and ramping up to full power could take months.But once it is working, it is expected to produce some startling findings.
Scientists plan to hunt for signs of the invisible “dark matter” and “dark energy” that make up more than 96 percent of the universe, and hope to glimpse the elusive Higgs boson, an undiscovered particle thought to give matter its mass.
The collider could find evidence of extra dimensions, a boon for superstring theory, which holds that quarks, the particles that make up atoms, are infinitesimal vibrating strings. The theory could resolve many of physics’ unanswered questions but requires about 10 dimensions — far more than the three spatial dimensions our senses experience.
The physicist Martin Rees has estimated the chance of an accelerator producing a global catastrophe at one in 50 million — long odds, to be sure, but about the same as winning some lotteries.
By contrast, a CERN team this month issued a report concluding that there is “no conceivable danger” of a cataclysmic event. The report essentially confirmed the findings of a 2003 CERN safety report, and a panel of five prominent scientists not affiliated with CERN, including one Nobel laureate, endorsed its conclusions.
Critics of the LHC filed a lawsuit in a Hawaiian court in March seeking to block its startup, alleging that there was “a significant risk that . . . operation of the collider may have unintended consequences, which could ultimately result in the destruction of our planet.”
On Tuesday, U.S. Justice Department lawyers representing the Department of Energy and the National Science Foundation filed a motion to dismiss the case. The two agencies have contributed $531 million to building the collider.
In rebutting doomsday scenarios, CERN scientists point out that cosmic rays have been bombarding the Earth and triggering collisions similar to those planned for the collider since the solar system formed 4.5 billion years ago. And so far, Earth has survived.
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How does the Large Hadron Collider work? Two beams of protons will race around a ring, 17 miles in circumference, 11,000 times a second in opposite directions. They will travel in two tubes about the width of fire hoses, speeding through a vacuum that is colder and emptier than outer space.
Their trajectory will be curved by supercooled magnets — to guide the beams around the rings and prevent the packets of protons from cutting through the surrounding magnets like a blowtorch.
The paths of these beams will cross, and a few of the protons in them will collide, at a series of cylindrical detectors along the ring. The two largest detectors are essentially huge digital cameras, capable of taking millions of snapshots a second.
Will it create a black hole? Critics have said the proton collisions might produce micro black holes, subatomic versions of cosmic black holes. Micro black holes produced by cosmic-ray collisions would likely be traveling so fast they would pass harmlessly through the Earth. Micro black holes produced by a collider, the skeptics theorize, would move more slowly and might be trapped inside the Earth’s gravitational field — and eventually threaten the planet.
Physicist John Ellis said doomsayers assume that the collider will create micro black holes in the first place, which he said was unlikely. And even if they appeared, he said, they would instantly evaporate, as predicted by the British physicist Stephen Hawking.
The Associated Press
