Consider an ancient example of a ‘discovery story’. Allegedly, the Greek mathematician Archimedes hit upon his famous principle while taking a bath. On the strike of inspiration, the ever-so-hygienic thinker leapt out of the water with a shout of ‘Eureka!’ Compare this image of the isolated, damp, naked mathematical genius with Wednesday’s announcement that, after years of scrabbling around the LHC and mutterings of ‘I definitely saw it here somewhere’, the Higg’s Boson has finally been located down the back of the subatomic sofa. The discovery, partly attributable to a team of over 10,000 scientists from 111 nations, is quite different to Archimedes’ Eureka moment. They’d need a very big bathtub, for a start.
The interesting thing about reports of Wednesday’s proceeding (apart from the revolution of 21st-century physics, which is also quite interesting) is the somewhat mixed messages about the nature of the ‘discovery’. According to the CERN press release and the morning conference, all that has been officially discovered is a new boson, with properties merely “consistent with the Higgs boson”. A tone of forced restraint loiters in all the reports. Nonetheless, CERN’s top brass were confident enough to hand the microphone to Peter Higgs, who thanked the assembled throng for discovering his namesake within his lifetime. And as the director of the US particle physics lab Fermilab argued, “if it looks like a duck and walks like a duck it’s going to be a duck”, which gives an insight into the surprisingly ornithological methods of high-end particle physics. Rudolf Heuer’s statement “as a layman, I would say we now have it” neatly sums up this split personality. As careful scientists, let’s not get too excited yet. But putting aside professional scepticism, HURRAH!
All this seems to be quite a modern phenomenon. When Galileo first saw the moons of Jupiter in 1610, and invited various noblemen to peer through his telescope and see for themselves, he was utterly convinced that his discovery was genuine. As many of the nobles failed to see the alleged moons, Galileo blamed their poor telescope technique. Ditto Isaac Newton when continental philosophers failed to replicate his prism experiments. A more recent example, and one that closely parallels the CERN story, is Arthur Eddington’s confirmation of Einstein’s General Relativity in 1919. Like the Higg’s Boson, Eddington knew exactly what he should be seeing if Einstein’s theory was correct. And when Eddington saw what he was hoping to see, the results were blared out at a prestigious meeting in London and through newspapers across the world (including the wonderful New York Times headline “Stars Not Where They Seemed or Were Calculated to Be, but Nobody Need Worry”). A telegram sent to Bertrand Russell began “dear Russell. Einstein’s theory now completely confirmed”. Never mind that, as the Harry Collins and Trevor Pinch show in their excellent short book The Golem, a more careful inspection of Eddington’s results reveals some rather brazen leaps of faith. The confidence shown by scientists and media across the world contrasts with the tone of today – a prediction was made, observations matched the predictions, so the right answer had obviously been discovered. No five-sigma levels of uncertainty here.
The whole five-sigma thing is interesting in its own right, in that it makes uncertainty an inherent part of discovery. Instead of the binary undiscovered / discovered nature of, say, Galileo’s moons around Jupiter, we end up with a graded scale of almost-discovery. The statistical certainty can never reach a full 100%; instead a discovery such as the Higg’s Boson is more ‘we’re really quite sure it can’t be anything else, probably. But we might be wrong.’ That’s not to criticise statistical definitions of discovery. Particularly in the field of particle physics, where the five-sigma cutoff was first set, it is a necessary step to deal with the huge mass of data coming from many different causes. A particle accelerator is a much busier place than the eyepiece of Eddington’s telescope, and forces scientists away from Galileo’s confidence and into CERN-like caution. But it is worth asking when the enduring image of the Eureka moment was replaced by this cumulative climb towards higher probability.
In truth, science has always been a bit like that. The sociologist of science Peter Galison points out that choosing to end an experiment, and to claim that you’ve got an answer, is always a bit of a judgement call. A discovery isn’t really any good until you’ve got people believing you, and they won’t believe you until you’ve amassed enough evidence. But how much is ‘enough’? For much of history, this has depended on the fierceness of your critics. But nowadays, in the era of Big Science like the LHC, you’ve also got to make sure all of your own side agree on the results too. In an earlier CERN breakthrough, the discovery of weak neutral currents over 1972-73, the image that clinched the deal had to pass through a chain of hierarchy. First a computer, then a lowly student, then a supervisor, then increasingly more impressive figures looked at a swathe of images they were handed from below, each time rejecting a chunk as uninteresting, until only the really interesting remained. It’s a nice thought that a game-changing image in 20th-century physics was first glimpsed by some lowly underpaid student in basement room Z, whose internship report would later read ‘my main tasks were making tea and overthrowing subatomic theory’. But even once the image had reached the high-and-mighty, they still had to call a series of meetings in London and Paris to ensure they all agreed on what had been discovered and – crucially – how they were going to publish it. As Galison points out, doing science always involves making decisions. Modern science, increasingly bureaucratic as it is, simply involves a lot more decisions.
Exactly when, how, and by whom the weak neutral current, or the Higg’s Boson for that matter, were ‘discovered’ will never be clear. But it isn’t really clear when the moons of Jupiter were discovered – when Galileo first saw smudges of something, when he worked out what the smudges were, or when he’d got enough people to believe in his smudges? After all, until the latter occurred he was just another crackpot with a shiny instrument. But we shouldn’t mourn the Eureka moment. It might be pleasingly dramatic to imagine a modern-day Archimedes simply noticing the Higgs floating towards the rubber duck. But we should also be proud that science has dealt with so much of the observable world around us that scientists are forced into finding order amidst some of the most complex patterns in nature, places where discoveries don’t appear in blinding flashes of sudden obviousness. And the footage from CERN on Wednesday shows that slow accumulation of probability can still be a cause for celebration. A Eureka Press Conference may sound less exciting than a Eureka Moment, but it still provides something worth leaping out of the bath for.
Official CERN press release: http://press.web.cern.ch/press/PressReleases/Releases2012/PR17.12E.html