Willard Frank Libby,1908 y\u0131l\u0131nda Colorado\u2019da do\u011fmu\u015f,radyoaktif karbonla,yani karbon 14 ile tarihleme y\u00f6ntemini geli\u015ftirerek 1960 Nobel Kimya \u00d6d\u00fcl\u2019\u00fc kazanm\u0131\u015f olan bilim adam\u0131d\u0131r.1933-1945 y\u0131llar\u0131 aras\u0131nda California \u00dcniversitesi\u2019nde fiziksel kimya dersleri verirken Manhattan Projesi\u2019nde g\u00f6rev alarak atom bombas\u0131n\u0131n yap\u0131m\u0131nda en \u00f6nemli a\u015fama olan uranyum izotoplar\u0131n\u0131n ayr\u0131lmas\u0131 y\u00f6ntemini geli\u015ftirmi\u015ftir.1945 y\u0131l\u0131nda Chicago \u00dcniversitesi\u2019ndeki N\u00fckleer Ara\u015ft\u0131rma Enstit\u00fcs\u00fc\u2019nde \u00e7al\u0131\u015fmaya ba\u015flad\u0131 ve bu g\u00f6revini 1959 y\u0131l\u0131na kadar s\u00fcrd\u00fcrd\u00fc.1980 y\u0131l\u0131nda \u00f6len Libby,1946 y\u0131l\u0131nda hidrojenin en a\u011f\u0131r izotopu olan trityumun, kozmik \u0131\u015f\u0131nlar\u0131n yard\u0131m\u0131yla \u00fcretilebilece\u011fini g\u00f6stermi\u015fti.
\nLibby,1947 y\u0131l\u0131nda radyokarbonla tarihlendirme y\u00f6ntemini geli\u015ftirmi\u015f,kemiklerin ve di\u011fer organik kal\u0131nt\u0131lar\u0131n ya\u015f\u0131n\u0131 kesinlikle saptama f\u0131rsat\u0131n\u0131 ilgili bilim adamlar\u0131na sunmu\u015ftu.
\n*
\nKarbon 14 ile tarihlendirme y\u00f6ntemi daha \u00f6nce hi\u00e7 uygulanmam\u0131\u015ft\u0131.O g\u00fcnlere kadar M\u0131s\u0131r Medeniyeti\u2019nin M\u00d6.3000 y\u0131llar\u0131na denk gelen Birinci Hanedanl\u0131k d\u00f6neminden daha eski olan kal\u0131nt\u0131lara g\u00fcvenilir \u015fekilde tarih verilemiyordu.Bu durumda son buz katmanlar\u0131n\u0131n ne zaman \u00e7ekildi\u011fini bilmek olanaks\u0131zd\u0131. Ayn\u0131 \u015fekilde Fransa\u2019da bulunan Lascaux magaralar\u0131n\u0131n duvarlar\u0131na \u00e7izilen resimlerin hangi tarihte yer ald\u0131\u011f\u0131n\u0131 kimse tam olarak s\u00f6yleyemiyordu. Libby\u2019in kuram\u0131,t\u00fcm canl\u0131lar\u0131n i\u00e7lerinde karbon 14 izotopu ta\u015f\u0131d\u0131klar\u0131 temelinden yola \u00e7\u0131k\u0131yordu.Canl\u0131lar \u00f6ld\u00fcklerinde bu izotop,\u00f6l\u00e7\u00fclebilir h\u0131zla bozunmaya ba\u015flar.
\nKarbon 14\u2019\u00fcn yar\u0131 \u00f6mr\u00fc yakla\u015f\u0131k 5.600 y\u0131ld\u0131r.
\n*
\nYar\u0131 \u00f6m\u00fcr,herhangi bir \u00f6rne\u011fin yar\u0131s\u0131n\u0131n yok olmas\u0131 i\u00e7in gereken s\u00fcredir.Bir yar\u0131 \u00f6m\u00fcr i\u00e7inde hangi y\u00fczde 50\u2019nin \u00f6lece\u011fi ve hangi y\u00fczde 50\u2019nin ya\u015fayaca\u011f\u0131 konusunda atomlar\u0131n nas\u0131l bir yol izledi\u011fi, istatistiksel bir olgudur.Yar\u0131 \u00f6m\u00fcr,temel maddeler i\u00e7in ge\u00e7erli olan,istatistiksel bir veri tablosudur.Yar\u0131 \u00f6mr\u00fc 30 saniye olan bir madde birimindeki her atom,tam tam\u0131na 30,60 ya da 90 saniye i\u00e7in var olacak anlam\u0131na gelmez.Yani,her atomun,kendisi i\u00e7in \u00f6ng\u00f6r\u00fclen bir d\u00fczenli s\u00fcre i\u00e7in varl\u0131\u011f\u0131n\u0131 s\u00fcrd\u00fcrece\u011fi demek de\u011fildir.Asl\u0131nda her atom,30\u2019un katlar\u0131yla ilgisi olmayan ve tamamen rastgele uzunlukta \u00f6m\u00fcrl\u00fcd\u00fcr.2 saniye sonra \u00f6lebilece\u011fi gibi y\u00fczlerce y\u0131l sonra da \u00f6lebilir.Bilebilece\u011fimiz tek husus,inceledi\u011fimiz \u00f6rne\u011fin t\u00fcm\u00fc i\u00e7in ge\u00e7erli olan yok olma h\u0131z\u0131n\u0131n,her 30 saniyede bir,atomlar\u0131n yar\u0131s\u0131n\u0131 yok edecek bi\u00e7imde s\u00fcrece\u011fidir.Bu,ortalama bir h\u0131zd\u0131r.
\n*
\nBelli bir karbon \u00f6rne\u011finin ne kadar bozunmu\u015f oldu\u011fu hesaplan\u0131rsa,o \u00f6rne\u011fi i\u00e7eren cismin ya\u015f\u0131 belirlenir.Ancak bu y\u00f6ntem her zaman ge\u00e7erli de\u011fildir.8 yar\u0131 \u00f6m\u00fcr sonras\u0131nda geriye kalan,ba\u015flang\u0131\u00e7taki radyoaktif karbonun sadece 1\/ 256\u2019s\u0131 olur.Bu miktar,g\u00fcvenilir bir \u00f6l\u00e7\u00fcm i\u00e7in \u00e7ok azd\u0131r.Bu nedenle hemen hemen 40.000 y\u0131ldan ya\u015fl\u0131 olmayan nesnelerde i\u015fe yarar.
\nLibby\u2019nin olu\u015fturdu\u011fu tarihleme y\u00f6ntemi yayg\u0131nla\u015fmaya ba\u015flam\u0131\u015ft\u0131 ki baz\u0131 kusurlar ta\u015f\u0131d\u0131\u011f\u0131 anla\u015f\u0131ld\u0131.Her \u015feyden \u00f6nce form\u00fcl\u00fcn temel elemanlar\u0131ndan biri olan bozunma sabiti,normalin y\u00fczde 3 kadar alt\u0131ndayd\u0131.Ancak bu yanl\u0131\u015fl\u0131k bilim d\u00fcnyas\u0131na duyuruluncaya kadar d\u00fcnyan\u0131n her taraf\u0131nda binlerce \u00f6l\u00e7\u00fcm yap\u0131lm\u0131\u015f bulunuyordu.Bu \u00f6l\u00e7\u00fcmlerin her birinin teker teker d\u00fczeltilmesi belki daha da karma\u015f\u0131kl\u0131\u011fa neden olabilirdi.Bu nedenle yanl\u0131\u015f olan bozunma sabiti d\u00fczeltilmeden b\u0131rak\u0131ld\u0131.Dolay\u0131s\u0131yla bug\u00fcn i\u00e7in radyokarbonla tarihlendirme y\u00f6ntemiyle belirlenmi\u015f olan her nesnenin ya\u015f\u0131,y\u00fczde 3 oran\u0131nda d\u00fc\u015f\u00fck bir rakamd\u0131r.
\nK\u0131sa bir s\u00fcre sonra bir sorun daha farkedildi. Karbon 14 \u00f6rneklerine ba\u015fka kaynaklardan,\u00f6rnekle beraber fark edilmeden kat\u0131lan maddelerin de etkili oldu\u011fu anla\u015f\u0131ld\u0131.En s\u0131k rastlanan hata,\u00f6rnekle beraber toplanan minik bir par\u00e7a ottan bula\u015fan karbondu.Ya\u015flar\u0131 20.000 y\u0131ldan fazla olmayan \u00f6rnekler i\u00e7in bu olay pek \u00f6nemli de\u011fildi.Ama daha ya\u015fl\u0131 \u00f6rnekler i\u00e7in ciddi sorundur.\u00c7\u00fcnk\u00fc bu ya\u015fl\u0131 \u00f6rneklerde,artakalan \u00e7ok az say\u0131da atomun say\u0131m\u0131 yap\u0131lmaktad\u0131r. Gen\u00e7 \u00f6rneklerde bu durum bin lira paray\u0131 sayarken bir liral\u0131k hata gibidir.Ya\u015fl\u0131 \u00f6rneklerde ise,iki liray\u0131 sayarken,hatal\u0131 say\u0131lan bir liran\u0131n \u00f6nemi kadard\u0131r.
\n*
\nDi\u011fer taraftan, Libby\u2019nin olu\u015fturdu\u011fu tarihleme y\u00f6ntemi,karbon 14\u2019\u00fcn atmosferde bulunan miktar\u0131n\u0131n ve canl\u0131lar taraf\u0131ndan emilme h\u0131z\u0131n\u0131n tarih boyunca ayn\u0131 kald\u0131\u011f\u0131 varsay\u0131m\u0131na dayan\u0131yordu.Oysa atmosferik karbon 14 miktar\u0131,Yerk\u00fcre manyetizmas\u0131n\u0131n kozmik \u0131\u015f\u0131nlar\u0131 sapt\u0131rmadaki ba\u015far\u0131 ya da ba\u015far\u0131s\u0131zl\u0131\u011f\u0131na ba\u011fl\u0131 olarak de\u011fi\u015fkenlik g\u00f6sterir.Bu ba\u015far\u0131 ya da ba\u015far\u0131s\u0131zl\u0131k zaman i\u00e7inde de\u011fi\u015fkendir.\u015eu halde baz\u0131 karbon 14 tarihlendirmeleri daha da ku\u015fkuludur.\u0130nsano\u011flunun Amerika k\u0131tas\u0131na ilk ayak bas\u0131\u015flar\u0131na yak\u0131n zamanlar en ku\u015fkulu tarihler aras\u0131ndad\u0131r.
\nBir di\u011fer geli\u015fme ile birlikte tarihlendirme sonu\u00e7lar\u0131, akla gelmeyen d\u0131\u015f fakt\u00f6rler nedeniyle iyice g\u00f6zden d\u00fc\u015ft\u00fc.\u00d6zellikle kemikleri teste tabi tutulan canl\u0131lar\u0131n beslenme al\u0131\u015fkanl\u0131klar\u0131 test sonu\u00e7lar\u0131n\u0131 etkiliyordu.Frenginin Yenid\u00fcnya\u2019dan m\u0131 yoksa Eskid\u00fcnya\u2019dan m\u0131 ortaya \u00e7\u0131kt\u0131\u011f\u0131 konusundaki tart\u0131\u015fma son darbeyi vurdu.\u0130ngiltere\u2019nin kuzeyinde \u00e7al\u0131\u015fan arkeologlar,bir manast\u0131r mezarl\u0131\u011f\u0131nda yatan ke\u015fi\u015flerin frengili olduklar\u0131n\u0131 bulgulad\u0131lar.\u0130lk ba\u015flarda bu ke\u015fi\u015flerin hastal\u0131\u011fa Amerika\u2019n\u0131n ke\u015ffinden \u00f6nce yakaland\u0131klar\u0131 sonucuna var\u0131lm\u0131\u015ft\u0131.Ama bir s\u00fcre sonra yap\u0131lan ara\u015ft\u0131rmalarla \u00e7ok fazla bal\u0131k yedikleri anla\u015f\u0131ld\u0131.Bal\u0131k a\u011f\u0131rl\u0131kl\u0131 beslenme,kemiklerin, oldu\u011fundan fazla ya\u015fl\u0131 g\u00f6r\u00fcnmesine sebep olabilirdi.Ger\u00e7i ke\u015fi\u015fler ger\u00e7ekten frengili idiler,ama bu hastal\u0131\u011fa nas\u0131l ve ne zaman yakalanm\u0131\u015flard\u0131?<\/p>\n","protected":false},"excerpt":{"rendered":"
Willard Frank Libby,1908 y\u0131l\u0131nda Colorado\u2019da do\u011fmu\u015f,radyoaktif karbonla,yani karbon 14 ile tarihleme y\u00f6ntemini geli\u015ftirerek 1960 Nobel Kimya \u00d6d\u00fcl\u2019\u00fc kazanm\u0131\u015f olan bilim adam\u0131d\u0131r.1933-1945 y\u0131llar\u0131 aras\u0131nda California \u00dcniversitesi\u2019nde fiziksel kimya dersleri verirken Manhattan Projesi\u2019nde g\u00f6rev alarak atom bombas\u0131n\u0131n yap\u0131m\u0131nda en \u00f6nemli a\u015fama olan uranyum izotoplar\u0131n\u0131n ayr\u0131lmas\u0131 y\u00f6ntemini geli\u015ftirmi\u015ftir.1945 y\u0131l\u0131nda Chicago \u00dcniversitesi\u2019ndeki N\u00fckleer Ara\u015ft\u0131rma Enstit\u00fcs\u00fc\u2019nde \u00e7al\u0131\u015fmaya ba\u015flad\u0131 ve bu …<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1407,1403],"tags":[4997,2137,4995,4998,4996],"class_list":["post-1948","post","type-post","status-publish","format-standard","hentry","category-fen-ve-teknoloji-odevleri","category-odevler","tag-chicago-universitesi","tag-izotop","tag-karbon-14-yonteminin-tarihcesi","tag-trityum","tag-willard-frank-libby"],"_links":{"self":[{"href":"https:\/\/www.islamidavet.com\/kutuphane\/wp-json\/wp\/v2\/posts\/1948","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.islamidavet.com\/kutuphane\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.islamidavet.com\/kutuphane\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.islamidavet.com\/kutuphane\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.islamidavet.com\/kutuphane\/wp-json\/wp\/v2\/comments?post=1948"}],"version-history":[{"count":0,"href":"https:\/\/www.islamidavet.com\/kutuphane\/wp-json\/wp\/v2\/posts\/1948\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.islamidavet.com\/kutuphane\/wp-json\/wp\/v2\/media?parent=1948"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.islamidavet.com\/kutuphane\/wp-json\/wp\/v2\/categories?post=1948"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.islamidavet.com\/kutuphane\/wp-json\/wp\/v2\/tags?post=1948"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}