The fellas at CERN have gone to great lengths to reassure us all that they won’t destroy the planet (who says physicists are cold hearted?).

The worry was that the collision of particles at the LHC’s high energies could create a black hole that would swallow the planet. We appear to be safe on that score but it turns out there’s another way in which some people think the LHC could cause a major explosion.

The worry this time is about Bose Einstein Condensates, lumps of matter so cold that their constituents occupy the lowest possible quantum state.

Physicists have been fiddling with BECs since the early 1990s and have become quite good at manipulating them with magnetic fields.

One thing they’ve found is that it is possible to switch the force between atoms in certain kinds of BECs from positive to negative and back using a magnetic field, a phenomenon known as a Feschbach resonance.

But get this: in 2001, Elizabeth Donley and buddies at JILA in Boulder, Colorado, caused a BEC to explode by switching the forces like. These explosions have since become known as Bose supernovas.

Nobody is exactly sure how these explosions proceed which is a tad worrying for the following reason: some clever clogs has pointed out that superfluid helium is a BEC and that the LHC is swimming in 700,000 litres of the stuff. Not only that but the entire thing is bathed in some of the most powerful magnetic fields on the planet.

So is the LHC a timebomb waiting to go off? Not according to Malcolm Fairbairn and Bob McElrath at CERN who have filled the back of a few envelopes in calculating that we’re still safe. To be doubly sure, they also checked that no other superfluid helium facilities have mysteriously blown themselves to kingdom come.

“We conclude that that there is no physics whatsoever which suggests that Helium could undergo
any kind of unforeseen catastrophic explosion,” they say.

That’s comforting and impressive. Ruling out foreseen catastrophies is certainly useful but the ability to rule out unforeseen ones is truly amazing.

Ref: arxiv.org/abs/0809.4004: There is no Explosion Risk Associated with Superfluid Helium in the LHC Cooling System

This entry was posted on Monday, September 29th, 2008 at 12:46 am and is filed under At the seaside, Calculatin', Fightin', Mean machines. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.