The Large Hadron Collider is there to create tiny collisions with a fantastically high energy-density. High enough that they expect particles to appear that have never been seen before. Maybe the famous Higgs Boson. Maybe something quite unexpected.
[This was written in 2008. The Higgs Boson was indeed found: reported as probable in 2012 and confirmed in 2013.]
It’s not a danger [contrary to the fears expressed at the time] because the amount of energy involved in any collision is very small. More drastic things happen in Earth’s atmosphere due to cosmic rays. And even if they produced a black hole, it would grow very slowly and might ‘evaporate’ due to Hawkins’s Radiation.
With sub-atomic particles, you get new particles created when they collide. This is related to the amount of energy in the collision. It’s like being in a restaurant with items at different prices – the more you can pay, the wider the range of dishes if you can pay. Now suppose you are in a Chinese restaurant and you can read the price but not what the dish is. Except you can read a little and have some notion – actual Chinese names for dishes are often rather weird and may give you no clue as to what you would be eating. You could order at random and see what turns up.
There was a flurry of media interest over the formal switch-on on Wednesday 10th September. In fact they had been using it before that, and the high-energe collisions come later. The plan was for collisions of ten tetravolts some time in November, then a shut-down and rebuild to get to the promised maximum of fourteen tetravolts. If there were dangers, they would apply then rather than now. The whole thing has anyway been shut down because of a technical fault, but not for more than a couple of months. Some time in early 2009 the big collisions will begin. But remember, though the energy density is high, the actual amount is rather small. I remember a New Scientist cartoon in which an ordinary 9-volt battery bore the label ‘danger – nine million microvolts’. It’s the same with CERN. As they put it:
“In absolute terms, these energies, if compared to the energies we deal with everyday, are not impressive. In fact, 1 TeV is about the energy of motion of a flying mosquito. What makes the LHC so extraordinary is that it squeezes energy into a space about a million million times smaller than a mosquito.” [Ask An Expert]
If one TeV is a mosquito, then 14 TeV would be about a flyswat. But concentration matters as much as force, that’s why a knife does damage and a razor much more so.
As for the usefulness, they expect to find just a few events that prove the existence of new particles. The most interesting is the Higgs Boson, which is the most plausible explanation as to why different particles have different masses, a proton much heavier than an electron and other particles heavier than a proton. It is called the ‘God Particle’, but that is a piece of silliness. If discovered or if disproved, it would not say anything about the origins of the Big Bang, the question that might have theological significance. the Big Bang may have come from nothing or from a meta-universe with different physical laws, this is still being talked about. But when physicists use a name loaded with emotional tags, it gets picked up. People suppose there is something mystical about an Einstein-Bose Condensate. I’m wondering what the media reaction will be when someone finally finds a Degenerate Fermi Gas!
Seriously, we already know that the universe as we know it originated in the Big Bang, 14 billion years ago and long before the formation of the Earth, about 4.5 billion years in a solar system that had already existing for about 500 million years and was still emerging from primaeval disorder. That actually matched the Norse Pagan creation mythology rather better than the myths of any higher religion. We did emerge between fire and ice, though the Norse version also has Primaeval Cow and similar gibberish. But it would be a nice line to throw at Christian ‘Fundamentalists’, whose Young Earth view is ludicrous and is also based mostly on the work of Bishop Usher, not anything the Bible actually says.
There is also a chance that CERN will provide evidence for one version of supersymmetry (often abbreviated SUSY). Supersymmetry is also a feature of most versions of string theory, though it can exist in nature even if string theory is wrong. In a year or two we may have a more definite idea. It is also possible they will find things that were not expected – call this the ‘Sedna Effect’, after the strange little world they found in the Kupier Belt but which is something quite different, thought to come from the much more distant Oort Cloud.
Every previous new experiment has found interesting stuff and it would be horrible bad luck if CERN does not. The problem is, these will be rare events and could be confused with two unrelated events that happen to overlap. Also the detectors are new and might produce false results. So it will take time before anything interesting develops.
None of it is likely to have any practical use, in terms of new consumer goods or weapons or medicine. This isn’t totally certain – high-temperature superconductors would be vastly important if they could get some cheap convenient material that does it, and new understandings of basic physics might give a clue. But my view is that new knowledge is worth having just for itself.
[As of June 15th 2015, no evidence of supersymmetry has been found. It might well turn up with the higher energies of the new run that is just beginning.]