: : © : Ready for blastoff: a Brookhaven engineer puts : finishing touches to the ion collider : Big Bang machine could : destroy Earth

: by Jonathan Leake : Science Editor : A NUCLEAR accelerator designed to replicate the : Big Bang is under investigation by international : physicists because of fears that it might cause : "perturbations of the universe" that could destroy the : Earth. One theory even suggests that it could create a : black hole.

: Brookhaven National Laboratories (BNL), one of the : American government's foremost research bodies, : has spent eight years building its Relativistic Heavy : Ion Collider (RHIC) on Long Island in New York state. : A successful test-firing was held on Friday and the : first nuclear collisions will take place in the autumn, : building up to full power around the time of the : millennium.

: Last week, however, John Marburger, Brookhaven's : director, set up a committee of physicists to : investigate whether the project could go disastrously : wrong. It followed warnings by other physicists that : there was a tiny but real risk that the machine, the : most powerful of its kind in the world, had the power : to create "strangelets" - a new type of matter made up : of sub-atomic particles called "strange quarks".

: The committee is to examine the possibility that, once : formed, strangelets might start an uncontrollable chain : reaction that could convert anything they touched into : more strange matter. The committee will also : consider an alternative, although less likely, possibility : that the colliding particles could achieve such a high : density that they would form a mini black hole. In : space, black holes are believed to generate intense : gravitational fields that suck in all surrounding matter. : The creation of one on Earth could be disastrous.

: Professor Bob Jaffe, director of the Centre for : Theoretical Physics at the Massachusetts Institute of : Technology, who is on the committee, said he : believed the risk was tiny but could not be ruled out. : "There have been fears that strange matter could alter : the structure of anything nearby. The risk is : exceedingly small but the probability of something : unusual happening is not zero."

: Construction of the £350m RHIC machine started : eight years ago and is almost complete. On Friday : scientists sent the first beam of particles around the : machine - but without attempting any collisions.

: Inside the collider, atoms of gold will be stripped of : their outer electrons and pumped into one of two : 2.4-mile circular tubes where powerful magnets will : accelerate them to 99.9% of the speed of light.

: The ions in the two tubes will travel in opposite : directions to increase the power of the collisions. : When they smash into each other, at one of several : intersections between the tubes, they will generate : minuscule fireballs of superdense matter with : temperatures of about a trillion degrees - 10,000 : times hotter than the sun. Such conditions are thought : not to have existed - except possibly in the heart of : some dense stars - since the Big Bang that formed : the universe between 12 billion and 15 billion years : ago.

: Under such conditions atomic nuclei "evaporate" into : a plasma of even smaller particles called quarks and : gluons. Theoretical and experimental evidence : predicts that such a plasma would then emit a shower : of other, different particles as it cooled down.

: Among the particles predicted to appear during this : cooling are strange quarks. These have been : detected in other accelerators but always attached to : other particles. RHIC, the most powerful such : machine yet built, has the ability to create solitary : strange quarks for the first time since the universe : began.

: BNL confirmed that there had been discussion over : the possibility of "perturbations in the universe". : Thomas Ludlam, associate project director of RHIC, : said that the committee would hold its first meeting : shortly.

: John Nelson, professor of nuclear physics at : Birmingham University who is leading the British : scientific team at RHIC, said the chances of an : accident were infinitesimally small - but Brookhaven : had a duty to assess them. "The big question is : whether the planet will disappear in the twinkling of an : eye. It is astonishingly unlikely that there is any risk - : but I could not prove it," he said. ::::::::::::::: I seem to remember that during the Trinity tests at Alamagordo, there was some speculation as to the possibility of the "A-Bomb" igniting the atmosphere of the Earth.