Contrary to claims by some scientists that the Large Hadron Collider (LHC) was being sabotaged from the future to save the world, it is back up and running. The LHC is now beyond the point where it was in 2008 when it had to be shut down just nine days after it had commenced sending beams around its 27km (17 mile) circuit on September 10 last year.
The culprit at the time was a poorly-soldered electrical splice, which overheated and led to a series of problems that damaged 53 of the LHC's 1,624 magnets among other components. Now, after repairs costing around €40 million (approx. US$59.9 million at the time of publication), the LHC is ready to get back to its task of smashing together particles traveling around a ring in opposite directions to shed light on the fundamental structure of matter and the origins of the universe.
There is still some way to go before the actual physics can begin, but scientists at the European Organization for Nuclear Research (CERN) say they have established circulating particle beams in both directions. The CERN team has decided to take things slowly, starting at just 3.5 trillion electron volts per beam – half of the 7 TeV that was originally intended. But if things continue to go smoothly they say they may be able to accelerate particles at the highest energy level ever tested before Christmas, although the full 7 TeV collisions wouldn't happen until next year.
The delay wasn't all bad news for the CERN scientists, who took advantage of the extra time to increase the sensitivity of the safeguards at the LHC so that if the collider is beset by another mishap, it would not sustain the same amount of damage as it did last year.
Now that the LHC has established circulating particle beams the next step is to smash them together in low-energy collisions that are expected to begin in around a week's time. Meanwhile, the high-energy collisions that are expected to unlock some of the secrets of the universe are expected to commence in January 2010.
The particles first go in opposite directions at close to the speed of light and are then re-routed to collide. When they crash head on, to my simple mind, their relative speed to the oncoming particles would be twice the speed of light.... but this is impossible since nothing can travel at more than the speed of light. Who can explain what goes on? Do the particles suddenly slow down and when they approach each other so they don\'t violate Einstein\'s theory?
It has to do with time dilatation. To the stationary observer, the particles are traveling near C (C=speed of light), and so their relative velocities are nearly 2C. But from the particle's point of view, time has slowed down everywhere else, so the other particle "appears" to be traveling at C relative to itself. Yeah. They "are" traveling 2C relative to each other, but by the time they actually collide they "aren't". I know it sounds like voodoo, but the effect is (apparently) observable and reproducible.