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aveled to the argonne national laboratory in illinois；where he was granted time on a late…model mass spectrograph； a machine capable of detectingand measuring the minute quantities of uranium and lead locked up in ancient crystals。 whenat last he had his results； patterson was so excited that he drove straight to his boyhood homein iowa and had his mother check him into a hospital because he thought he was having aheart attack。
soon afterward； at a meeting in wisconsin； patterson announced a definitive age for theearth of 4；550 million years （plus or minus 70 million years）鈥斺�渁 figure that stands unchanged 50 years later；鈥潯s mcgrayne admiringly notes。 after two hundred years of trying；the earth finally had an age。
his main work done； patterson now turned his attention to the nagging question of all thatlead in the atmosphere。 he was astounded to find that what little was known about the effectsof lead on humans was almost invariably wrong or misleading鈥攁nd not surprisingly； hediscovered； since for forty years every study of lead鈥檚 effects had been funded exclusively bymanufacturers of lead additives。
in one such study； a doctor who had no specialized training in chemical pathologyundertook a five…year program in which volunteers were asked to breathe in or swallow leadin elevated quantities。 then their urine and feces were tested。 unfortunately； as the doctorappears not to have known； lead is not excreted as a waste product。 rather； it accumulates inthe bones and blood鈥攖hat鈥檚 what makes it so dangerous鈥攁nd neither bone nor blood wastested。 in consequence； lead was given a clean bill of health。
patterson quickly established that we had a lot of lead in the atmosphere鈥攕till do； in fact；since lead never goes away鈥攁nd that about 90 percent of it appeared to e fromautomobile exhaust pipes； but he couldn鈥檛 prove it。 what he needed was a way to parelead levels in the atmosphere now with the levels that existed before 1923； when tetraethyllead was introduced。 it occurred to him that ice cores could provide the answer。
it was known that snowfall in places like greenland accumulates into discrete annual layers（because seasonal temperature differences produce slight changes in coloration from winter tosummer）。 by counting back through these layers and measuring the amount of lead in each； hecould work out global lead concentrations at any time for hundreds； or even thousands； ofyears。 the notion became the foundation of ice core studies； on which much modernclimatological work is based。
what patterson found was that before 1923 there was almost no lead in the atmosphere； andthat since that time its level had climbed steadily and dangerously。 he now made it his life鈥檚quest to get lead taken out of gasoline。 to that end； he became a constant and often vocalcritic of the lead industry and its interests。
it would prove to be a hellish campaign。 ethyl was a powerful global corporation withmany friends in high places。 （among its directors have been supreme court justice lewispowell and gilbert grosvenor of the national geographic society。） patterson suddenly foundresearch funding withdrawn or difficult to acquire。 the american petroleum institutecanceled a research contract with him； as did the united states public health service； asupposedly neutral government institution。
as patterson increasingly became a liability to his institution； the school trustees wererepeatedly pressed by lead industry officials to shut him up or let him go。 according to jamielincoln kitman； writing in the nation in 2000； ethyl executives allegedly offered to endow achair at caltech 鈥渋f patterson was sent packing。鈥潯bsurdly； he was excluded from a 1971national research council panel appointed to investigate the dangers of atmospheric leadpoisoning even though he was by now unquestionably the leading expert on atmospheric lead。
to his great credit； patterson never wavered or buckled。 eventually his efforts led to theintroduction of the clean air act of 1970 and finally to the removal from sale of all leadedgasoline in the united states in 1986。 almost immediately lead levels in the blood ofamericans fell by 80 percent。 but because lead is forever； those of us alive today have about625 times more lead in our blood than people did a century ago。 the amount of lead in theatmosphere also continues to grow； quite legally； by about a hundred thousand metric tons ayear； mostly from mining； smelting； and industrial activities。 the united states also bannedlead in indoor paint； 鈥渇orty…four years after most of europe；鈥潯s mcgrayne notes。
remarkably； considering its startling toxicity； lead solder was not removed from americanfood containers until 1993。
as for the ethyl corporation； it鈥檚 still going strong； though gm； standard oil； and du pontno longer have stakes in the pany。 （they sold out to a pany called albemarle paper in1962。） according to mcgrayne； as late as february 2001 ethyl continued to contend 鈥渢hatresearch has failed to show that leaded gasoline poses a threat to human health or theenvironment。鈥潯n its website； a history of the pany makes no mention of lead鈥攐r indeedof thomas midgley鈥攂ut simply refers to the original product as containing 鈥渁 certainbination of chemicals。鈥�
ethyl no longer makes leaded gasoline； although； according to its 2001 pany accounts；tetraethyl lead （or tel as it calls it） still accounted for 25。1 million in sales in 2000 （out ofoverall sales of 795 million）； up from 24。1 million in 1999； but down from 117 million in1998。 in its report the pany stated its determination to 鈥渕aximize the cash generated bytel as its usage continues to phase down around the world。鈥潯thyl markets tel through anagreement with associated octel of england。
as for the other scourge left to us by thomas midgley； chlorofluorocarbons； they werebanned in 1974 in the united states； but they are tenacious little devils and any that youloosed into the atmosphere before then （in your deodorants or hair sprays； for instance） willalmost certainly be around and devouring ozone long after you have shuffled off。 worse； weare still introducing huge amounts of cfcs into the atmosphere every year。 according towayne biddle； 60 million pounds of the stuff； worth 1。5 billion； still finds its way onto themarket every year。 so who is making it？ we are鈥攖hat is to say； many of our largecorporations are still making it at their plants overseas。 it will not be banned in third worldcountries until 2010。
clair patterson died in 1995。 he didn鈥檛 win a nobel prize for his work。 geologists neverdo。 nor； more puzzlingly； did he gain any fame or even much attention from half a century ofconsistent and increasingly selfless achievement。 a good case could be made that he was themost influential geologist of the twentieth century。 yet who has ever heard of clair patterson？
most geology textbooks don鈥檛 mention him。 two recent popular books on the history of thedating of earth actually manage to misspell his name。 in early 2001； a reviewer of one ofthese books in the journal nature made the additional； rather astounding error of thinkingpatterson was a woman。
at all events； thanks to the work of clair patterson by 1953 the earth at last had an ageeveryone could agree on。 the only problem now was it was older than the universe thatcontained it。
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11 MUSTER MARK鈥橲 QUARKS
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in 1911； a british scientist 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。 back in the cavendish labin cambridge he built an artificial cloud chamber鈥攁 simple device in which he could cooland moisten the air； creating a reasonable model of a cloud in laboratory conditions。
the device worked very well； but had an additional； unexpected benefit。 when heaccelerated an alpha particle through the chamber to seed his make…believe clouds； it left avisible trail鈥攍ike the contrails of a passing airliner。 he had just invented the particle detector。
it provided convincing evidence that subatomic particles did indeed exist。
eventually two other cavendish scientists invented a more powerful proton…beam device；while in california ernest lawrence at berkeley produced his famous and impressivecyclotron； or atom smasher； as such devices were long excitingly known。 all of thesecontraptions worked鈥攁nd indeed still work鈥攐n more or less the same principle； the ideabeing to accelerate a proton or other charged particle to an extremely high speed along a track（sometimes circular； sometimes linear）； then bang it into another particle and see what fliesoff。 that鈥檚 why they were called atom smashers。 it wasn鈥檛 science at its subtlest； but it wasgenerally effective。
as physicists built bigger and more ambitious machines； they began to find or postulateparticles or particle families seemingly without number： muons； pions； hyperons； mesons； k…mesons； higgs bosons； intermediate vector bosons； baryons； tachyons。 even physicists beganto grow a little unfortable。 鈥測oung man；鈥潯nrico fermi replied when a stude