IN 1911, A British stist named C. T. R. Wilson was studying cloud formations bytramping regularly to the summit of Ben Nevis, a famously damp Scottish mountain, when itoccurred to him that there must be an easier way to study clouds. Ba the dish Labin Cambridge he built an artificial cloud chamber—a simple devi which he could cooland moisten the air, creating a reasonable model of a cloud in laboratory ditions.
The device worked very well, but had an additional, ued be. When heaccelerated an alpha particle through the chamber to seed his make-believe clouds, it left avisible trail—like the trails of a passing airliner. He had just ied the particle detector.
It provided ving evidehat subatomic particles did indeed exist.
Eventually two other dish stists ied a more powerful proton-beam device,while in California Er Lawre Berkeley produced his famous and impressivecyclotron, or atom smasher, as such devices were loingly known. All of thesetraptions worked—and iill work—on more or less the same principle, the ideabeing to accelerate a proton or other charged particle to aremely high speed along a traetimes circular, sometimes linear), then bang it into another particle and see what fliesoff. That』s why they were called atom smashers. It wasn』t sce at its subtlest, but it wasgenerally effective.
As physicists built bigger and more ambitious maes, they began to find or postulateparticles or particle families seemingly without number: muons, pions, hyperons, mesons, K-mesons, Higgs bosons, intermediate vector bosons, baryons, tas. Even physicists beganto grow a little unfortable. 「Young man,」 Enrico Fermi replied when a student asked himthe name of a particular particle, 「if I could remember the names of these particles, I wouldhave been a botanist.」
Today accelerators have hat sound like something Flash Gordon would use inbattle: the Super Proton Synchrotron, the Large Ele-Positron Collider, the Large HadronCollider, the Relativistic Heavy Ion Collider. Using huge amounts of energy (some operateonly at night so that people in neighb towns don』t have to witheir lights fadihe apparatus is fired up), they whip particles into such a state of livelihat asingle ele do forty-seven thousand laps around a four-mile tunnel in a sed. Fearshave been raised that in their enthusiasm stists might iently create a black hole oreven something called 「strange quarks,」 which could, theoretically, i with othersubatomic particles and propagate untrollably. If you are reading this, that hasn』thappened.
Finding particles takes a certain amount of tration. They are not just tiny and swiftbut also often tantalizingly eva. Particles e into being and be gone again in aslittle as 0.000000000000000000000001 sed (10-24). Even the most sluggish of unstableparticles hang around for no more than 0.0000001 sed (10-7).
Some particles are almost ludicrously slippery. Every sed the Earth is visited by 10,000trillion trillion tiny, all but massless rinos (mostly shot out by the nuclear broilings of theSun), and virtually all of them pass right through the pla and everything that is on it,including you and me, as if it weren』t there. To trap just a few of them, stists anksholding up to 12.5 million gallons of heavy water (that is, water with a relative abundance ofdeuterium in it) in underground chambers (old mines usually) where they 』t be interferedwith by other types of radiation.
Very occasionally, a passirino will b