The Large Hadron Collider (LHC) will conduct its biggest test yet today. The LHC has been accelerating twin particle streams for the past 10 days, and they are now reaching 3.5 trillion electron volts (TeV), a world record.
Today the two streams will be guided into each other, and the ensuing collision mapped and recorded, although the operators say this could take some time.
"With two beams at 3.5 TeV, we are on the verge of launching the LHC physics programme," explained Cern's director for accelerators and technology, Steve Myers.
"But we've still got a lot of work to do before collisions. Just lining the beams up is a challenge in itself. It's a bit like firing needles across the Atlantic and getting them to collide half way."
The problems will come from trying to direct the streams using huge super-cooled magnets. It was the failure of the cooling system for these magnets that shut down the LHC when it first started operating.
The LHC has been designed to detect the so-called Higgs boson which, it is theorised, is vital to imparting objects with mass.
Professor Stephen Hawking and others postulate that the Higgs boson does not exist, and the LHC is an attempt to settle the question once and for all and provide vital data on the conditions at the start of the universe.
The project has not been without its detractors, however, who assert that the LHC has the potential to destroy the planet or allow time travel, but the scientists involved are confident that the LHC is safe.
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