July 29, 2008. Copyright, 2008, Graphic News. All rights reserved

One of the coolest places in the universe

LONDON, July 29, Graphic News: Deep beneath the Swiss-French border near Geneva, thousands of physicists are building the world’s largest and most expensive science experiment -- a particle accelerator that will smash subatomic particles together to recreate the moments after the Big Bang.

Located in a 27km (17-mile) tunnel, 100 metres below ground, lies CERN’s Large Hadron Collider. The purpose of the LHC is to make protons -- hydrogen nuclei -- travel at nearly the speed of light until they smash together, pulverising one another and emitting a shower of sub-particles that will reveal mysteries about the makeup of matter.

The cancellation of America’s Superconducting Super Collider in 1993 left the way open for the $8bn LHC to become the de facto global physics laboratory.

The first aim of scientists working on the LHC is to confirm the existence of the Higgs boson, which was proposed by Peter Higgs at Edinburgh University in the 1960s to explain how mass is related to matter in the Standard Model of particle physics. It is the only Standard Model particle not yet observed.

The search for the elusive boson calls for conditions that existed moments after the universe came into existence, just seconds after the Big Bang, 13.7 billion years ago.

The giant super-conducting magnets used to accelerate the proton beams have to be chilled using liquid helium to minus 271.3°C -- less than two degrees above absolute zero -- making the lab one of the coldest places in the universe.

The beams travel in an ultrahigh vacuum equivalent to deep space and 10 times less than the pressure on the moon. Altogether some 600 million collisions will take place every second in the four particle detectors positioned around the accelerator.

Besides the Higgs boson, some of the 9,000 scientists hope the LHC will also reveal dimensions predicted by “string theory”. The popular hypothesis posits that at least six other dimensions exist in addition to our four familiar ones -- length, width, depth and time.

Miniature black holes are another possible product of the project. While the majority of collisions will be between protons, the LHC will also smash together the far heavier nuclei of lead atoms. These will generate temperatures of 10 billion degrees -- a million times hotter than the centre of the sun.

“We are recreating a tiny volume of matter that is very similar to the universe one-millionth of a second after the Big Bang,” said David Evans, senior scientist at the so-called ALICE particle detector. “We are more likely to find black holes than in the proton-proton collisions.”

These possibilities have alarmed German physicist Otto Rossler who claims that these lead ion collisions will produce black holes that will swallow the entire planet. Others, fearing the creation of “strangelets” -- hypothetical particles that could also trigger disaster -- have even filed a lawsuit in the U.S. seeking to prevent the LHC from opening on safety grounds. 

While CERN physicists expect to generate micro black holes at the rate of about one per second, they say they’ll evaporate instantaneously. For billions of years, much more powerful cosmic rays have battered our planet without creating an Earth-eating black hole, they say, so there’s no reason to think that the LHC will create planet-threatening particles.

The LHC is scheduled to become operational in October and run for 20 years, with an upgrade planned for 2016.
/ENDS