Geneva - What is described as the biggest and most expensive experiment in scientific history got under way Wednesday as scientists started up a 10 billion-dollar underground facility aimed at exploring the origin of matter.

A beam of particles was being accelerated around a massive tunnel or "ring" 27-kilometres in circumference - the so-called Large Hadron Collider (LHC) - located near Geneva on the French-Swiss border.

Physicists at the European Organization for Nuclear Research - known by its French acronym CERN - applauded as the initial beam was successfully turned on at the start of a series of experiments which will go on for years.

The scientists were due later in the day to introduce the first atomic particles into the beam, which during the course of the long line of experiments will be subjected to intense scrutiny.

Of central interest to the cameras recording their behaviour micro- seconds at a time will be how they collide at speeds approaching light.

The idea is to create conditions believed to be similar to those moments after the Big Bang which most physicists believe to have been the origin of the universe.

The so-called "Big Bang Day," when two proton beams will go onto a pre-set collision course, is not expected to occur for a year or so. (dpa)