Hurray for the European Court of Human Rights. It has rejected an emergency injunction to block the Large Hadron Collider from turning on on 10 September. It's the latest legal case brought against the LHC by scientists who fear that the world's largest particle accelerator will produce fearsome entities that could destroy the Earth.
I'm thrilled that the ECHR has understood the science and has given the LHC the green light. Because let's get something straight: the world is not going to end on 10 September.
Here's why. Next week physicists will attempt to send a beam of protons all the way round the LHC's 27-kilometre ring for the very first time. What they won't do is accelerate the beam to its design energy of 7 teraelectronvolts (TeV). And unless the tests are very, very successful, they won't be smashing protons head on either.
Instead, a lone beam of protons will make its way round with just 450 gigelectronvolts of energy. The only collisions that could happen is if the beam smashes into one of the very few air molecules that haven't been sucked out of the ring, which has a vacuum 10 times better than on the moon.
Supposing this does happen, the collision energy will be a paltry 30 gigaelectronvolts (30 GeV). That's a far cry from the 14 TeV collision energy that the LHC will produce when it is running at full speed. You simply can't make much in the way of heavy, exotic particles with just 30 GeV of energy. No top quarks, no W or Z particles, no Higgs bosons. And that's just the regular stuff: there certainly is not enough energy to make mini black holes, strangelets, magnetic monopoles or anything else exotic that critics purport could destroy the Earth.
OK, so we have a reprieve of a few months until physicists finish their tests and start creating collisions with 14 TeV of energy. What will happen then? This is uncharted territory for particle accelerators. And the trouble with venturing into the unknown is that you don’t know what will be there. This is what excites physicists and, perhaps understandably, is grist for the mill for doom-mongers.
Theorists have speculated about all manner of things popping into existence, including the infamous mini black holes. Critics claim that these will grow uncontrollably as they suck in matter, eventually gobbling everything in their path. One such opponent is Otto Rössler, a theoretical chemist at the University of Tübingen in Germany, and one of the plaintiffs in the ECHR case. He claims that in the worst case, the Earth could be eaten by a mini black hole in 50 months.
Really, I don't think so. I admit I have a hard time believing theorists' usual line that Stephen Hawking will save us. Hawking's most famous research shows that black holes - the giant ones we see in space - slowly evaporate due to a process called Hawking radiation. Being much smaller, mini black holes should evaporate within microseconds. Trouble is, no one has seen Hawking radiation. So why should I put humanity's hopes in a theoretical physicist?
No, for me, there is a much more compelling argument why the LHC won't destroy the world. And it doesn't rely on theoretical flights of fancy. Whatever the LHC churns up out of all the collision energy, we've been there before. Cosmic rays from outer space are raining down on us all the time and they can reach truly staggering energies. You can get the same collision energy as the LHC from a 108-GeV cosmic ray slamming into the atmosphere. And there are plenty of cosmic rays with such energies.
Cosmic ray experiments all over the world - experiments that have nothing to do with the CERN laboratory where the LHC is based - have found that about 10-14 rays with energy greater than the LHC strike each square centimetre of Earth every second. That might not sound like much. But over the Earth’s 4.5 billion year lifetime, that makes 1022 collisions or 100,000 times more than the LHC will ever produce. Obviously, in that time no mini black holes, vacuum bubbles, killer strangelets or any other weird effects have eaten the planet.
Not convinced? Scale the cosmic ray sums up to cover the 100 billion stars in the Milky Way and the 100 billion galaxies in the visible universe and you find that nature has already made the equivalent of 1031 LHCs. Or if you like, 10 trillion LHCs are running every second. And we're still here.
New Scientist LHC Area
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