I’ve launched myself into the blogosphere just a bit too late for the feeding frenzy surrounding the switching on of the Large Hadron Collider at CERN last week. Obviously the event itself was a bit of a non-event as it will take years for anything interesting to come out the other end of its multi-billion-dollar tunnel. There are a couple of things worth saying in retrospect, though, now that the dust has settled.
The first is about all this nonsense concerning the creation of black holes that could destroy the Earth. If it were possible to create black holes in the LHC then they would be very puny ones, not capable of destroying anything very much at all. The phrase “black hole” conjures up Hollywood-style images of dead stars rampaging through the Galaxy devouring planets and costing a fortune in special effects. But not all black holes are massive enough to be stars in movies. If the LHC could make black holes it would only make very titchy ones. Since the gravitational effect of a black hole depends on its mass – and these little ones have very little of that – any that did pop out of an event in the LHC would be more of a pin-prick than a hole…
Moreover, energetic particles in the form of cosmic rays are constantly raining down on the Earth’s atmosphere, colliding with hadrons as they do so. The most extreme cosmic rays have energies far in excess of the limit that can be reached by the LHC. If an energetic hadron collision were going to produce a black hole that could destroy the planet, it would have happened a very long time ago and we wouldn’t be around to discuss the possibility.
So how did this daft idea come to dominate the news coverage surrounding the switch-on of the LHC? The press are never reluctant to peddle the doomsday scenario whenever they can as it appears to sell newspapers. But there is probably a bit more to it than that. I think part of it is a side-effect of the exaggerated language used by particle physicists in their attempt to use the LHC to capture the public imagination. “The Big Bang Machine” is just one example. If the experiment were really attempting to recreate the Big Bang, then there would indeed be much to be scared about. But the fact of the matter is that the LHC doesn’t reach energies anything like those reached in the Big Bang (nor even in the many smaller bangs that our Universe indulges in from time to time, such as supernova explosions).
The maximum energy reached by the LHC is going to be about 7 TeV (roughly equivalent to the energy of a bumble bee in flight). Although the very earliest stages of the Big Bang itself are not well understood, we are pretty sure that the primordial fireball started off with energies at least a million million (i.e. 1,000,000,000,000) times larger than this. It is doubtful (to say the least) that we’ll ever be able to build a device capable of reaching such energies, so the only “Big Bang Machine” there will ever be is the one we happen to be living in.
This is perhaps the reason why particle physicists are so desperate to glean maximum publicity for the LHC. It’s cost – though not extreme when compared to, for example, military spending – far exceeds that of any other scientific experiment. When it is over, will it be possible to build an even bigger experiment to probe even deeper into the subatomic world? Funding of such experiments generally comes from the public purse and it seems more than likely that the taxpayer will draw the line very soon. Although it won’t destroy the world, perhaps the LHC is nevertheless the end of the line for experimental physics of that kind.
So by all means let’s celebrate the LHC. It’s a wonderful demonstration of what international cooperation can achieve. It is also a response to the need all humans have to ask questions about our Universe. But let us not forget that our ability to probe the inner space of particles with experiments will always be limited, while the outer space beyond the stars offers much wider horizons.
PS. I can’t resist adding this link, as the best example of the worst of the hysteria about the LHC.
PPS. And this one, which explains why the LHC really is safe.
In the Dark 