The first beam in the Large Hadron Collider at CERN flashed around the 27km particle accelerator at 9.30 this morning.
It has been hailed as an historic event in the search for an answer to the question: "where did it all begin?"
According to LHC project leader Lyn Evans, "we can now look forward to a new era of understanding about the origins and evolution of the universe."
The role of UK scientists and engineers in this experiment has been considerable. For an example of this read more
about ALICE.
Once colliding beams have been established, there will be a period of measurement and calibration for the LHC's four major experiments, and new results could start to appear in around a year.
It is also hoped that experiments at the LHC will allow physicists to look at gravity in new ways and investigate the origins of black holes.