Finally they are ready to restage the birth of time

In the beginning was the creation. Now scientists try again . . .

Science Correspondent

The Universe is a few days away from its second Big Bang - though this one will be more modest than the first, 15 billion years ago, which brought everything into existence. This time, a couple of particles that survive for a few billionths of a second will suffice.

The repeat is scheduled for Monday, and will occur about 50 metres below the Jura foothills near Geneva, as part of a series of experiments in the particle accelerator operated by CERN, the European laboratory for particle physics.

But instead of a whole Universe, CERN's scientists will be happy - in fact, overjoyed - to create some particles that have never been observed, though they have been predicted by theory for years. They hope the experiments, due to start after calibration tests this weekend, will produce a particle known as a "chargino" - one of the missing links in the enormous cast of subatomic particles predicted by theory. This belongs to a class of particles known as "supersymmetrical" (because of their mathematical properties rather than their shape) and theory suggests that they play a crucial - if elusive - part in subatomic physics.

Discovering a chargino "would be a major discovery that would reveal a new facet of nature," said Chris Llewellyn-Smith, CERN's director, yesterday.

However, the 400-strong team on the Large Electron-Positron Collider (LEP) must first create conditions similar to those an instant after the Big Bang - the moment when the Universe came into being. In the superhot, superdense environment that existed then, supersymmetrical particles could have existed fleetingly as separate objects. As the Universe expanded and cooled, they became inseparable constituents of ordinary matter.

CERN's LEP will recreate those early conditions by accelerating beams of electrons and their antiparticle, positrons, almost to the speed of light around the 26-kilometre accelerator buried near Geneva. The beams will be whirled in opposite directions around the accelerator, gaining energy until they are brought together in a reaction chamber, where they will annihilate each other in a pure blast of energy. Instantaneously, the energy density in the chamber will echo that one ten-billionth of a second after the Big Bang - and so should allow the re-creation of the particles that were able to exist then.

If the "chargino" is discovered, it would help to tie together strands of theoretical physics which have for years attempted to link the four forces of nature - electrical, gravitational, the "strong" nuclear force (which holds the nuclei of atoms together) and the "weak" nuclear force (which allows particles called neutrinos to interact with other matter).

"Supersymmetrical particles connect them all," said Dr Llewellyn-Smith. "It would be one of the greatest discoveries."

If it happens, it would make up for one of CERN's most embarrassing discoveries a fortnight ago: two empty Heineken beer bottles which had reached the parts that beer should not reach.

The bottles were found in the high-vacuum tube of the accelerator, after earlier calibration tests had puzzlingly produced no results at all. This, it turned out, was because the particle beams had been absorbed by the glass.