{"id":10325,"date":"2010-02-01T14:25:48","date_gmt":"2010-02-01T12:25:48","guid":{"rendered":"http:\/\/109.232.216.219\/~bilimvegelecek\/?p=10325"},"modified":"2017-05-25T14:57:24","modified_gmt":"2017-05-25T11:57:24","slug":"yerin-yasina-iliskin-darwin-kelvin-tartismasindan-gunumuze-arzin-merkezinde-olup-bitenlere-dair","status":"publish","type":"post","link":"https:\/\/bilimvegelecek.com.tr\/index.php\/2010\/02\/01\/yerin-yasina-iliskin-darwin-kelvin-tartismasindan-gunumuze-arzin-merkezinde-olup-bitenlere-dair","title":{"rendered":"Yer\u2019in ya\u015f\u0131na ili\u015fkin Darwin-Kelvin tart\u0131\u015fmas\u0131ndan g\u00fcn\u00fcm\u00fcze Arz\u2019\u0131n merkezinde olup bitenlere dair"},"content":{"rendered":"

Ba\u015f\u0131n\u0131 Lord Kelvin\u2019in \u00e7ekti\u011fi fizik\u00e7iler, yerbilimcilerin ve Darwin\u2019in Evrim kuram\u0131n\u0131n \u201cs\u0131n\u0131rs\u0131z zaman\u201d ilkesine sava\u015f a\u00e7m\u0131\u015flard\u0131. Darwin\u2019i dahi gerilettiler, ama daha sonra ula\u015f\u0131lan bilimsel ger\u00e7ekler 19. y\u00fczy\u0131l\u0131n k\u00f6t\u00fcmser fizi\u011fini \u00e7\u00fcr\u00fctt\u00fc. G\u00fcn\u00fcm\u00fczde ise ayn\u0131 konuda daha farkl\u0131 bir tart\u0131\u015fma var. Yer\u2019in merkezindeki varl\u0131\u011f\u0131 baz\u0131lar\u0131nca savlanan baz\u0131lar\u0131nca yads\u0131nan h\u0131zl\u0131 \u00fcretken reakt\u00f6rde neler olup bitiyor? Ve bu olup bitenler y\u00fczeye nas\u0131l yans\u0131yor? <\/em><\/p>\n

Prof. Dr. E. Rennan Pek\u00fcnl\u00fc<\/strong><\/p>\n

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Charles Darwin\u2019in geli\u015ftirmi\u015f oldu\u011fu evrim kuram\u0131n\u0131n ilk ilkesi, s\u0131n\u0131rs\u0131z zamand\u0131r. Bu ilk ilke, d\u00f6nemin yerbilimcilerinin bilimsel bulgular\u0131 ve do\u011fa felsefeleri temelinde onanm\u0131\u015f bir ilkedir. Hem Lamarck hem de Darwin organik de\u011fi\u015fimlerin olabil\u00addi\u011fince yava\u015f olarak ger\u00e7ekle\u015fti\u011fi varsay\u0131m\u0131n\u0131 kulland\u0131. 19. y\u00fczy\u0131l\u0131n ilk yar\u0131s\u0131nda ger\u00e7ekle\u015ftirilen bilim\u00adsel bulgular ve bu bulgular\u0131 temel alarak yap\u0131lan s\u0131n\u0131rs\u0131z zaman var\u00adsay\u0131mlar\u0131 H\u0131ristiyan \u00f6\u011fretisindeki \u201cYarad\u0131l\u0131\u015f<\/strong>\u201d i\u00e7in bi\u00e7ilen zamanla \u00e7eli\u015fiyordu. Bir\u00e7ok \u00f6nde gelen Kilise, Yer\u2019in \u0130sa\u2019dan \u00f6nce 4004 y\u0131l\u0131nda yarat\u0131ld\u0131\u011f\u0131n\u0131 \u00f6\u011fretiyordu. Oysa Hutton, Playfair ve di\u011fer bilim insanlar\u0131n\u0131n \u00e7abalar\u0131, s\u0131n\u0131rs\u0131z zaman kavram\u0131n\u0131 do\u011frulayan bulgulara g\u00f6t\u00fcr\u00fcyordu. Asl\u0131nda bu \u00e7abalar, Darwin\u2019in T\u00fcrlerin K\u00f6keni<\/em> adl\u0131 yap\u0131t\u0131n\u0131n alt yap\u0131s\u0131n\u0131 olu\u015fturmu\u015ftu.<\/p>\n

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Lord Kelvin ve di\u011fer fizik\u00e7ilerin yerbilime ve evrime sald\u0131r\u0131lar\u0131<\/em><\/strong><\/p>\n

Ancak ne tuhaft\u0131r ki, T\u00fcrlerin K\u00f6keni<\/em>\u2019nin yay\u0131nlanmas\u0131ndan 6 y\u0131l gibi k\u0131sa bir s\u00fcre sonra s\u0131n\u0131rs\u0131z jeolojik zaman kavram\u0131na \u015fiddetli bir sald\u0131r\u0131 y\u00f6neltildi. 19. y\u00fczy\u0131l\u0131n sonlar\u0131na gelindi\u011finde bir\u00e7ok do\u011fa bilimci do\u011fal se\u00e7ilim (natural selection) ilkesine ku\u015fkuyla bakmaya ba\u015flad\u0131. Bu sald\u0131r\u0131 Darwin\u2019in de \u00f6zg\u00fcvenini sarst\u0131; Huxley, savunusunu bilimsel nesnelli\u011fe dayand\u0131raca\u011f\u0131 yerde so\u00adfizme ba\u015fvurdu ve genel anlamda yerbilim, dersini \u00e7al\u0131\u015fmam\u0131\u015f bir \u00f6\u011frencinin \u00f6\u011fretmenleri kar\u015f\u0131s\u0131ndaki ac\u0131n\u0131lacak durumuna d\u00fc\u015fm\u00fc\u015ft\u00fc.<\/p>\n

Yerbilime dolays\u0131z, dirimbilime de dolayl\u0131 olarak y\u00f6neltilen bu sald\u0131r\u0131, bir\u00e7ok tarih\u00e7inin 19. y\u00fczy\u0131\u00adl\u0131n \u00f6nde gelen fizik\u00e7isi olarak tan\u0131mlad\u0131\u011f\u0131 Lord Kelvin\u2019den gelmi\u015fti. 19. y\u00fczy\u0131l\u0131n ortala\u00adr\u0131nda ba\u015flayan ve yar\u0131m y\u00fczy\u0131l s\u00fcren s\u0131n\u0131rs\u0131z jeolojik zaman tart\u0131\u015fmas\u0131nda Kelvin\u2019in sav\u0131 yayg\u0131n olarak kullan\u0131ld\u0131 ve fizik\u00e7iler s\u0131n\u0131r\u00ads\u0131z zaman\u0131n yanl\u0131\u015fl\u0131\u011f\u0131n\u0131 kan\u0131tlamaya \u00e7al\u0131\u015ft\u0131; ancak son \u00e7\u00f6z\u00fcmlemede kan\u0131t\u00adlanan kendi ba\u015far\u0131s\u0131zl\u0131klar\u0131 oldu. O d\u00f6nemde fizik\u00e7iler yerbilim\u00adcilere \u201camat\u00f6r\u201d bilimciler g\u00f6z\u00fcyle bak\u0131yordu. Fizik\u00e7iler, \u00f6zellikle de Kelvin, yerbilimcilerin savlar\u0131n\u0131 dikkate alm\u0131yor, okumaya bile yana\u015fm\u0131yordu. Ancak zaman bu \u201camat\u00f6r\u00adleri\u201d do\u011frulad\u0131. Yine 19. y\u00fczy\u0131la d\u00f6necek olursak, fizik\u00e7ilerin dolayl\u0131 sald\u0131r\u0131s\u0131na u\u011frayan Darwin ve dirimbilimciler i\u00e7in durum hi\u00e7 de i\u00e7 a\u00e7\u0131c\u0131 de\u011fildi. Dirimbilim Yer\u2019deki ya\u015fam\u0131n \u00e7ok \u00e7e\u015fitlili\u011finin kayna\u011f\u0131 olarak yava\u015f de\u011fi\u015fimi g\u00f6steriyordu; bu sav\u0131n \u00f6z\u00fcnde de s\u0131n\u0131rs\u0131z zaman yat\u0131yordu. Entropinin s\u00fcrekli artt\u0131\u011f\u0131n\u0131, \u201c\u0131s\u0131 \u00f6l\u00fcm\u00fcne\u201d do\u011fru gidildi\u011fini savunan fizik\u00e7iler, fiyakal\u0131 matema\u00adtiksel form\u00fclleriyle dirimbilimcilerin ve yerbilimcilerin zaman \u00f6l\u00e7e\u011fine bir k\u0131s\u0131tlama getirdiler. Zaman \u00f6l\u00e7e\u011fine bir k\u0131s\u0131tlama getirilecekse, dirimbilimciler yava\u015f de\u011fi\u015fimi yads\u0131\u00admak ve yerine d\u0131\u015f etkenlere ba\u011fl\u0131 olmayan ve yazg\u0131s\u0131 \u00f6nceden belirlen\u00admi\u015f bir evrimi ve dolay\u0131s\u0131yla tanr\u0131sal bir de\u011fi\u015fimi onamak zorunda kala\u00adcakt\u0131.<\/p>\n

Lord Kelvin ve \u00e7al\u0131\u015fma arkada\u015f\u0131 Peter Tait\u2019in dirimbilimi bekleyen bu ka\u00e7\u0131n\u0131lmaz de\u011fi\u015fim gere\u011fini \u00f6ng\u00f6r\u00fcp g\u00f6remedikleri bir merak konusudur! Ancak \u015furas\u0131 kesin ki, her ikisi de dinsel g\u00f6revlerini aksat\u00admadan yerine getiren koyu H\u0131ristiyan ki\u015filerdi. \u0130ster dinsel ister bilim\u00adsel d\u00fcrt\u00fcyle g\u00fcd\u00fclm\u00fc\u015f olsun, bu iki bilim adam\u0131 dirimbilimcilerin ve yerbilimcilerin \u00fczerine ac\u0131mas\u0131zca gittiler. Bug\u00fcn, Yer \u00fczerindeki ya\u015fam\u0131n tarihi en tutucu bir rakamla 3 milyar y\u0131l olarak belirlenmi\u015ftir. Ancak, Kelvin ve Tait\u2019in Yer\u2019e bi\u00e7tikleri 10-30 milyon y\u0131ll\u0131k ge\u00e7mi\u015f, Darwin kuram\u0131na korkun\u00e7 k\u0131s\u0131tlamalar dayatm\u0131\u015ft\u0131. S\u0131n\u0131rs\u0131z zaman i\u00e7inde yava\u015f de\u011fi\u015fimi kendine temel alm\u0131\u015f olan evrim kuram\u0131 ve do\u011fal se\u00e7ilim ilkesi, fizik\u00e7ilerin dayatt\u0131\u011f\u0131 cinsten k\u0131sa bir zaman aral\u0131\u011f\u0131nda organik ya\u015fam\u0131n nas\u0131l \u00e7e\u015fitlilik kazanabilece\u011fini a\u00e7\u0131klaya\u00admazd\u0131.<\/p>\n

Bu geli\u015fmenin tarih\u00e7esine bakt\u0131\u011f\u0131m\u0131zda, 1894 y\u0131l\u0131nda Lord Salisbu\u00adry\u2019nin \u0130ngiliz Bilimi \u0130lerletme Toplulu\u011fu\u2019na ba\u015fkanl\u0131k etti\u011fi bir toplant\u0131da yapm\u0131\u015f oldu\u011fu dikkat \u00e7ekici bir konu\u015fmaya tan\u0131k oluruz. Bu konu\u015fmas\u0131nda Lord Salisbury, Darwin\u2019\u00adin s\u0131n\u0131rs\u0131z zaman hipotezine iki noktada kar\u015f\u0131 \u00e7\u0131k\u0131yor: Birincisi, Darwin\u2019in kullanm\u0131\u015f oldu\u011fu y\u00f6ntemle evrim i\u00e7in yeterli zaman\u0131n buluna\u00admayaca\u011f\u0131; ikincisi ise, do\u011fal se\u00e7ilimi ayr\u0131nt\u0131lar\u0131yla kan\u0131tlaman\u0131n olas\u0131 olmayaca\u011f\u0131 y\u00f6n\u00fcndeydi.<\/p>\n

Darwin\u2019in evrim kuram\u0131na olan tepkiler dozunu o denli ka\u00e7\u0131rm\u0131\u015ft\u0131 ki, Columbia \u00dcniversitesi Rekt\u00f6r\u00fc Barnard 1873 y\u0131l\u0131nda yapt\u0131\u011f\u0131 bir de\u011ferlendirmeyle \u201ckaranl\u0131\u011fa\u201d olan \u00f6zlemini \u015f\u00f6yle dile getirmi\u015fti: \u201cDarwin\u2019in organik evrimi do\u011fruysa, Tanr\u0131\u2019n\u0131n varl\u0131\u011f\u0131na inanmak olas\u0131 de\u011fildir. E\u011fer \u00e7a\u011fda\u015f bilimin sonu\u00e7lar\u0131 t\u00fcrlerin bu denli \u00e7abuk gelip ge\u00e7ici oldu\u011funu sergilemekse ben daha fazla bilim istemiyorum. Benden \u00f6nce atalar\u0131m nas\u0131l cahil ya\u015fad\u0131ysa ben de \u00f6yle cahil ya\u015famak istiyorum.\u201d<\/p>\n

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Lord Kelvin ve di\u011fer fizik\u00e7ilerin Yer\u2019e bi\u00e7tikleri 10-30 milyon y\u0131ll\u0131k ge\u00e7mi\u015f, Darwin kuram\u0131na korkun\u00e7 k\u0131s\u0131tlamalar dayatm\u0131\u015ft\u0131.<\/figcaption><\/figure>\n

Lord Kelvin\u2019in kar\u015f\u0131 \u00e7\u0131k\u0131\u015f nedeni, 18. y\u00fczy\u0131l\u0131n sonlar\u0131nda geli\u015fmeye ba\u015flayan evrensel evrim d\u00fc\u015f\u00fcncelerinin ka\u00e7\u0131n\u0131lmaz sonu\u00e7lar\u0131y\u00add\u0131. Lord Kelvin yerbilimci de\u011fil, fizik\u00e7iydi. \u0130ncelemesine ba\u015flarken Yer\u2019in ilk olu\u015fum a\u015famas\u0131nda erimi\u015f durumda bulunan bir k\u00fctle oldu\u011funu ve zamanla so\u011fuyup g\u00fcn\u00fcm\u00fczdeki kat\u0131 durumuna geldi\u011fini varsaym\u0131\u015ft\u0131. Yapt\u0131\u011f\u0131 \u00f6l\u00e7\u00fcmlerde Yer y\u00fczeyindeki kayalardaki \u0131s\u0131 ak\u0131s\u0131n\u0131 yakla\u015f\u0131k, bir y\u0131lda 1 cm2 de 40 kalori olarak saptama becerisini g\u00f6stermi\u015fti. Di\u011fer yandan, Yer\u2019in s\u0131cakl\u0131\u011f\u0131n\u0131n derinlikle artt\u0131\u011f\u0131n\u0131 ve bu art\u0131\u015f\u0131n her 100 metrede yakla\u015f\u0131k 2\u00b0 C oldu\u011funu da biliyordu. Kelvin baz\u0131 kayalar\u0131n erime s\u0131cakl\u0131\u011f\u0131n\u0131 bildi\u011finden bu kayalar\u0131n \u0131s\u0131 iletkenli\u011fini \u00f6l\u00e7t\u00fc ve \u00e7al\u0131\u015fmalar\u0131n\u0131, \u201c20-40 milyon y\u0131l \u00f6nce Yer y\u00fczeyinin, ya\u015fama destek veremeyecek denli s\u0131cak oldu\u011fu\u201d de\u011ferlendirmesiyle noktalad\u0131. Kelvin\u00ad\u2019in ya\u015f saptama y\u00f6ntemi son derece zeki bir y\u00f6ntemdi. Ancak bug\u00fcn Kel\u00advin\u2019in bulmu\u015f oldu\u011fu bu de\u011ferin yanl\u0131\u015f oldu\u011funu biliyoruz. Kelvin\u2019in hesaplamalar\u0131 ni\u00e7in yanl\u0131\u015ft\u0131? Ba\u015fl\u0131ca yan\u0131lg\u0131s\u0131 kuram\u0131n\u0131n varsay\u0131m\u0131nda yat\u0131yordu. Kelvin, Yer\u2019in i\u00e7 k\u0131s\u0131mlar\u0131nda \u00fcretilen \u0131s\u0131n\u0131n, Yer\u2019in erimi\u015f durumda oldu\u011fu o ilk olu\u015fum zamanlar\u0131ndan arda kalan art\u0131k \u0131s\u0131 (residual heat) oldu\u011funu varsaym\u0131\u015ft\u0131. Bug\u00fcn art\u0131k bu \u0131s\u0131n\u0131n Yer\u2019in i\u00e7 katmanlar\u0131nda bulunan radyoaktif elementlerin bozunmas\u0131 sonucunda \u00fcretilen \u0131s\u0131 oldu\u011funu biliyoruz. Bu \u0131s\u0131 ak\u0131s\u0131, \u00e7ok uzun zaman aral\u0131klar\u0131nda g\u00f6receli olarak sabit kalm\u0131\u015f ve kalacak olan \u0131s\u0131d\u0131r.<\/p>\n

Kelvin\u2019in bu varsay\u0131m\u0131n\u0131n ge\u00e7ersiz oldu\u011funun bilinmedi\u011fi d\u00f6nem\u00adlere, 19. y\u00fczy\u0131l\u0131n ikinci yar\u0131s\u0131na d\u00f6nelim. Termodinami\u011fin ikinci yasas\u0131 (entropinin s\u00fcrekli artt\u0131\u011f\u0131n\u0131 savu\u00adnan \u015fu \u00fcnl\u00fc ilke!) yerbilimciler aras\u0131nda giderek daha fazla onay kazanmaya ba\u015flam\u0131\u015ft\u0131. \u00d6rne\u011fin, yerbi\u00adlimci George Greenboug, Londra Yerbi\u00adlim Toplulu\u011fu\u2019nun y\u0131ll\u0131k toplant\u0131s\u0131n\u00adda yapt\u0131\u011f\u0131 konu\u015fmada \u015fu saptamay\u0131 yap\u0131yordu: \u201cGezegenimiz so\u011fumas\u0131n\u0131 s\u00fcrd\u00fcr\u00fcrken, organik ya\u015fam Tertiary \u00e7a\u011f\u0131n ba\u015f\u0131ndan bu yana kendini g\u00f6stermeye ba\u015flam\u0131\u015ft\u0131r.\u201d<\/p>\n

Ayn\u0131 d\u00f6nemlerde tart\u0131\u015f\u0131lan G\u00fcne\u015f\u2019in \u0131s\u0131 ya\u015f\u0131 ve Yer \u00fczerindeki ya\u015fam \u00fczerine olan etkisi sorunu art\u0131k \u0131s\u0131 sorununa eklenince yerbi\u00adlimde bir reform yapma gere\u011fine ili\u015fkin istemler kendisini duyumsat\u00admaya ba\u015flad\u0131. Bu d\u00f6nemde Lord Kelvin: \u201c\u0130ngiliz pop\u00fcler yerbilimi do\u011fa felsefesine dolays\u0131z olarak kar\u015f\u0131 \u00e7\u0131k\u0131yor\u201d bi\u00e7iminden saptamalar yap\u0131yordu. Uniformitarian yerbilim\u00adciler Yer\u2019in olu\u015fumuna ili\u015fkin kuram\u00adlar\u0131nda zaman\u0131n ne ba\u015flang\u0131c\u0131ndan ne de sonundan s\u00f6z ediyorlard\u0131. Lord Kelvin, termodinami\u011fin ikinci yasas\u0131n\u0131n i\u015faret etti\u011fi \u201cger\u00e7eklere\u201d dayanarak yerbilimcilere dolays\u0131z, dirimbilimcilereyse dolayl\u0131 olarak meydan okuyordu (Darwin, evrim kuram\u0131 i\u00e7in gerekli s\u0131n\u0131rs\u0131z zaman kavram\u0131n\u0131 yerbilimcilerden alm\u0131\u015ft\u0131). 19. y\u00fczy\u0131\u00adl\u0131n sonuna gelinmi\u015fti ve bu iki d\u00fc\u015fman kamp varl\u0131\u011f\u0131n\u0131 s\u00fcrd\u00fcr\u00fcyordu. Bu konuda 1862-1902 d\u00f6neminde yaz\u0131lanlar dev boyutlara \u00e7\u0131km\u0131\u015ft\u0131. Kelvin ve fizik\u00e7i arkada\u015flar\u0131n\u0131n yerbilimci ve dirimbilimciler \u00fczerine yapm\u0131\u015f oldu\u011fu bu etkiyi bo\u015flamak olas\u0131 de\u011fildi. O d\u00f6nemin dolu dizgin geli\u015fen fizi\u011fini g\u00f6z \u00f6n\u00fcne ald\u0131\u011f\u0131m\u0131zda bu etkiden kurtulman\u0131n ger\u00e7ekten olas\u0131 olmad\u0131\u011f\u0131n\u0131 anlar\u0131z. Bir\u00e7ok yerbilimci bu etkiye esir d\u00fc\u015fm\u00fc\u015f ve Yer\u2019in ya\u015f\u0131na ili\u015fkin hesaplamalar\u0131n\u0131 g\u00f6zden ge\u00e7irerek Yer\u2019i \u201cgen\u00e7le\u015ftirmi\u015flerdir\u201d. Dirimbilimcilerin \u00e7\u0131kmaz\u0131 daha da b\u00fcy\u00fckt\u00fc. Bu \u00e7\u0131kmazdan kurtulabilmek i\u00e7in kuramlar\u0131na bir\u00e7ok yara band\u0131 (epicycle) yap\u0131\u015ft\u0131rmak zorunda kald\u0131lar.<\/p>\n

Lord Kelvin bu konudaki d\u00fc\u015f\u00fcncelerini 1860 y\u0131l\u0131nda yazd\u0131\u011f\u0131 \u00fc\u00e7 b\u00fcy\u00fck makalede yay\u0131nlad\u0131. Macmillan\u2019s Magazine<\/em>\u2019e yazd\u0131\u011f\u0131 ve Helmholtz ve di\u011fer fizik\u00e7ilerin de destekledi\u011fi makalesi \u201cG\u00fcne\u015f\u2019in \u0131s\u0131 ya\u015f\u0131\u201d \u00fczeri\u00adneydi. Bu makalenin ana d\u00fc\u015f\u00fcncesi, G\u00fcne\u015f\u2019in \u0131s\u0131 ve \u0131\u015f\u0131k veren s\u0131v\u0131 bir k\u00fctle oldu\u011fu ve \u00e7evresine h\u0131zla erke da\u011f\u0131tt\u0131\u011f\u0131 \u00fczerineydi. Bu saptamas\u0131n\u00addan sonra Kelvin, G\u00fcne\u015f\u2019in gelecek ya\u015fam\u0131n\u0131n son derece k\u0131sa, ge\u00e7mi\u015finin ise \u00e7ok uzun olmad\u0131\u011f\u0131n\u0131, dolay\u0131s\u0131yla bir zamanlar g\u00fcn\u00fcm\u00fczden daha s\u0131cak oldu\u011funu savunuyordu. Benzer bir makalesinde de gelece\u011fe y\u00f6nelik d\u00fc\u015f\u00fcncelerini \u015f\u00f6yle s\u0131ral\u0131yordu: \u201c\u015euras\u0131 kesin ki, gezegenimizin canl\u0131lar\u0131, ya\u015famlar\u0131 i\u00e7in gerekli olan G\u00fcne\u015f \u0131s\u0131 ve \u0131\u015f\u0131\u011f\u0131ndan daha bir\u00e7ok milyon y\u0131l yararlanma olana\u011f\u0131na sahip olamayacaklar.\u201d<\/p>\n

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Lord Kelvin\u2019\u00acin matematiksel \u201ckan\u0131t\u0131ndan\u201d ka\u00e7maya \u00e7al\u0131\u015fan ve yap\u0131lan sald\u0131r\u0131lardan tedirgin olan Darwin, T\u00fcrlerin K\u00f6keni\u2019nin 6. bask\u0131s\u0131nda baz\u0131 \u201cd\u00fczeltmelere\u201d gitmek zorunda kalm\u0131\u015ft\u0131.<\/figcaption><\/figure>\n

Ku\u015fkusuz Kelvin zaman\u0131nda atom erkesi hen\u00fcz bulunma\u00adm\u0131\u015ft\u0131. Ancak ayn\u0131 erke, Kelvin\u2019in k\u00f6t\u00fcmser g\u00f6zl\u00fckleriyle bakt\u0131\u011f\u0131 Yer\u2019i milyarlarca y\u0131ldan beri \u0131s\u0131t\u0131yordu. Bug\u00fcn \u00e7a\u011fda\u015f bilim, G\u00fcne\u015f \u0131s\u0131s\u0131n\u0131n ilk olu\u015fum zamanlar\u0131ndan g\u00fcn\u00fcm\u00fcze ge\u00e7en milyarlarca y\u0131l boyunca duyumsanamayacak denli az de\u011fi\u015fti\u011fini s\u00f6yl\u00fcyor. E\u011fer tersi olsayd\u0131 gezegenimizdeki ya\u015fam s\u00fcreklili\u011fini koruyamazd\u0131.<\/p>\n

Kelvin\u2019in 1865 y\u0131l\u0131nda yazd\u0131\u011f\u0131 ve yerbilimcilere dolays\u0131z olarak meydan okuyan makalesinin ba\u015fl\u0131\u011f\u0131 \u201cYerbilimdeki Uniformity Doktrininin Yads\u0131nmas\u0131\u201d bi\u00e7imindeydi. Bu makale, \u0131s\u0131 yitirilmesini temel alm\u0131\u015ft\u0131. Kelvin, uniformitarian yerbilimciler ve onlar\u0131n sonu\u00e7lar\u0131n\u0131 kullanan dirimbilimcilerin gereksinim duydu\u011fu s\u0131n\u0131rs\u0131z zaman boyunca Yer kabu\u011funun kararl\u0131l\u0131\u011f\u0131n\u0131 koruyamayaca\u011f\u0131n\u0131 mate\u00admatiksel olarak kan\u0131tlamaya\u00a0 \u00e7al\u0131\u015fm\u0131\u015ft\u0131. O d\u00f6nem, fizi\u011fin genelde parlak bir d\u00f6nemiydi. Thomas Huxley, Charles Darwin ve di\u011fer do\u011fa bilim\u00adcileri fizi\u011fin sald\u0131r\u0131lar\u0131 kar\u015f\u0131s\u0131nda gerileme g\u00f6stermeye ba\u015flam\u0131\u015flard\u0131. 1871 y\u0131l\u0131nda Wallace\u2019a yazd\u0131\u011f\u0131 mek\u00adtupta Darwin\u2019in ac\u0131lar\u0131 ve kayg\u0131lar\u0131 a\u00e7\u0131k\u00e7a duyumsan\u0131yordu: \u201cG\u00fcne\u015f ve Yer\u2019in k\u0131salm\u0131\u015f olan ya\u015flar\u0131n\u0131 hen\u00fcz \u00f6z\u00fcmseyebilmi\u015f de\u011filim\u201d. Kelvin kazanm\u0131\u015f oldu\u011fu bu \u00fcst\u00fcnl\u00fc\u011f\u00fc ac\u0131ma\u00ads\u0131zca s\u00fcrd\u00fcr\u00fcyordu. 1893 y\u0131l\u0131nda Kelvin \u015f\u00f6yle yaz\u0131yordu: \u201cDarwin felse\u00adfesinin k\u0131s\u0131rl\u0131\u011f\u0131 her a\u015famada bir kez daha sergileniyor\u201d. Clarence King, 1893 y\u0131l\u0131nda Yer\u2019in 24 milyon ya\u015f\u0131nda oldu\u011funu duyurmu\u015f, Kelvin de bu saptamaya kat\u0131lm\u0131\u015ft\u0131.<\/p>\n

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Yer\u2019in merkezini g\u00f6steren bir \u00e7izim<\/figcaption><\/figure>\n

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G\u00fcne\u015f bal\u00e7\u0131kla s\u0131vanam\u0131yor!<\/em><\/strong><\/p>\n

Yerbilimcilerin fizik\u00e7iler kar\u015f\u0131s\u0131ndaki \u00e7aresizli\u011fi dirimbilimcileri de bir \u00e7\u0131k\u0131\u015f noktas\u0131 aramaya zorluyordu. Bu \u00e7aba anti-Darwinci ak\u0131m\u0131n ortaya \u00e7\u0131kt\u0131\u011f\u0131 bir d\u00f6nemde oluyordu. Bu d\u00f6nem entelekt\u00fcel karma\u015fan\u0131n bask\u0131n oldu\u011fu bir d\u00f6nemdi. Bu kar\u0131\u015f\u0131k d\u00f6nem, Gregor Mendel\u2019in yeniden ke\u015ffine g\u00f6t\u00fcren ara\u015ft\u0131rmala\u00adr\u0131n uyart\u0131ld\u0131\u011f\u0131 bir d\u00f6nemdi. Darwin bu yeni ak\u0131m\u0131n mayalanmas\u0131ndan \u00f6nce ya\u015fam\u0131n\u0131 yitirdi. T\u00fcrlerin K\u00f6keni<\/em>\u2019nin 6. bask\u0131\u00ads\u0131nda Darwin, Lord Kelvin\u2019in do\u011fal se\u00e7ilime kar\u015f\u0131 g\u00f6sterdi\u011fi kar\u015f\u0131 \u00e7\u0131k\u0131\u015f\u0131n a\u015f\u0131lmas\u0131 zor bir \u00e7\u0131k\u0131\u015f oldu\u011funu onad\u0131.<\/p>\n

T\u00fcrlerin K\u00f6keni<\/em>\u2019nin son bask\u0131s\u0131 dikkatli bir bi\u00e7imde incelenirse, kuram\u0131na y\u00f6neltilen kar\u015f\u0131 \u00e7\u0131k\u0131\u015fa yan\u0131t vermek amac\u0131yla Darwin, b\u00fcy\u00fck emek verdi\u011fi yap\u0131t\u0131na serpi\u015ftirdi\u011fi \u201cd\u00fczeltmeler\u201dle yap\u0131t\u0131n \u00e7eli\u015fkilerle dolmas\u0131na neden olmu\u015ftur. Kitab\u0131n 6. bask\u0131s\u0131n\u0131n XI. b\u00f6l\u00fcm\u00fcnde \u015f\u00f6yle bir t\u00fcmceyle kar\u015f\u0131la\u015f\u0131yoruz: \u201cY\u00fcksek d\u00fczeyde \u00f6rg\u00fctlenmi\u015f olan organizmalardaki de\u011fi\u015fiklikler, d\u00fc\u015f\u00fck d\u00fczeydekilere k\u0131yas\u00adla daha h\u0131zl\u0131 olmu\u015ftur.\u201d Kitab\u0131n ba\u015fka bir b\u00f6l\u00fcm\u00fcndeyse, Lord Kelvin\u2019\u00adin matematiksel \u201ckan\u0131t\u0131ndan\u201d ka\u00e7maya \u00e7al\u0131\u015fan Darwin, \u00f6nceki bask\u0131lardakinin tam tersi bir saptamaya gidiyor: \u201cYer\u2019in erken d\u00f6nemlerinde fiziksel ko\u015fullardaki de\u011fi\u015fim g\u00fcn\u00fcm\u00fczde kar\u015f\u0131la\u015ft\u0131\u011f\u0131m\u0131z de\u011fi\u015fikliklerden daha h\u0131zl\u0131 ve \u015fiddetli olmu\u015ftur; dolay\u0131s\u0131yla, o d\u00f6nemin neden oldu\u011fu dirimsel de\u011fi\u015fiklikler de o denli h\u0131zl\u0131 olmu\u015ftur.\u201d Darwin\u2019in, Lord Kelvin\u2019in bask\u0131lar\u0131yla T\u00fcrlerin K\u00f6keni<\/em>\u2019ne yapm\u0131\u015f oldu\u011fu bu son \u201conar\u0131mlar\u201d kuram\u0131n metafizik \u00f6\u011felerle dolmas\u0131na neden olmu\u015ftur. Darwin\u2019in uzla\u015fma iste\u011fi, kendi kuram\u0131nda \u00e7arp\u0131c\u0131 tutars\u0131zl\u0131klar ortaya \u00e7\u0131karm\u0131\u015ft\u0131r. Ancak T\u00fcrlerin K\u00f6keni<\/em> klasik bir yap\u0131t d\u00fczeyine \u00e7\u0131kt\u0131\u011f\u0131ndan bu sap\u0131n\u00e7lar d\u00fc\u015fmanlar\u0131n\u0131n bile g\u00f6z\u00fcnden ka\u00e7m\u0131\u015ft\u0131r.<\/p>\n

Dirimbilim \u00fczerine yap\u0131lan bu tuhaf ve yanl\u0131\u015f bask\u0131, Darwin\u2019i, T\u00fcrlerin K\u00f6keni<\/em>\u2019ni yay\u0131nlamas\u0131yla birlikte tedirgin etmeye ba\u015flad\u0131. Darwin Lamarck\u2019a do\u011fru geriledi. Di\u011fer yandan, Kelvin\u2019in sonu\u00e7lar\u0131ndan ku\u015fku duyan birka\u00e7 yerbilimci vard\u0131. Bunlarda biri olan F. R. Moulton, 1899 y\u0131l\u0131nda, bilinmeyen bir t\u00fcr atom erkesinin s\u0131n\u0131rs\u0131z jeolojik zaman\u0131 sa\u011flayabilece\u011fini d\u00fc\u015f\u00fcnd\u00fc. Bu \u00f6ng\u00f6r\u00fc, sonraki on y\u0131l i\u00e7inde do\u011frulu\u011funu g\u00f6sterdi. 1903 y\u0131l\u0131nda Paul Curie ve Laborde radyumun s\u00fcrekli olarak \u00e7evresinden daha s\u0131cak kald\u0131\u011f\u0131n\u0131 g\u00f6sterdi. Yerbilim ve G\u00f6kbilim atom erkesine ili\u015fkin bu yeni bulgunun \u00f6nemini kavramada gecikmedi. G\u00fcne\u015f\u2019in bir k\u00f6m\u00fcr y\u0131\u011f\u0131n\u0131 gibi h\u0131zla yanarak t\u00fckendi\u011fini savu\u00adnan Kelvinci g\u00f6r\u00fc\u015f ayn\u0131 h\u0131zla \u00e7\u00f6kt\u00fc, fiyakal\u0131 matematiksel hesaplar anlam\u00ads\u0131z bir y\u0131\u011f\u0131na d\u00f6n\u00fc\u015ft\u00fc. Kayalardaki uranyum bile\u015feni, art\u0131k \u0131s\u0131n\u0131n yiti\u00adrilmesine ili\u015fkin \u00f6\u011fretiyi yerle bir etti! B\u00f6ylece Yer\u2019in ya\u015f\u0131na ili\u015fkin s\u0131n\u0131rs\u0131z zaman kavram\u0131 yeniden ya\u015fam buldu. Fizik\u00e7ilerin uzun s\u00fcren zor\u00adbal\u0131\u011f\u0131 sona ermi\u015fti. Is\u0131 \u00f6l\u00fcm\u00fc ya da evrenbilimcilerin yayg\u0131n tan\u0131m\u0131yla \u201cB\u00fcy\u00fck Buzul\u201dun, bir \u015faka olmaktan ba\u015fka bir \u015fey olmad\u0131\u011f\u0131 g\u00f6sterildi. So\u011fuktan donan ve b\u00fcz\u00fclen bir gezegenin yerine, daima gen\u00e7, s\u0131cakl\u0131\u011f\u0131 en ulu da\u011flar\u0131n yal\u00e7\u0131n tepelerine de\u011fin yay\u0131lan ve ya\u015fam kayna\u011f\u0131 atomun derinliklerinde yatan bir gezegen ge\u00e7iyordu. 19. y\u00fczy\u0131l\u0131n k\u00f6t\u00fcmser fizi\u011fi \u00e7\u00fcr\u00fct\u00fclm\u00fc\u015f, G\u00fcne\u015f ve G\u00fcne\u015f\u2019te yatan atom erkesi \u00fczerine \u00e7al\u0131\u015fmalar ba\u015flam\u0131\u015ft\u0131.<\/p>\n

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Yer\u2019in \u00f6ze\u011finde n\u00fckleer reakt\u00f6r m\u00fc var?<\/em><\/strong><\/p>\n

Darwin sonras\u0131 d\u00f6nemde Yer\u2019in \u0131s\u0131 kaynaklar\u0131 \u00fczerine \u00e7al\u0131\u015fmalar h\u0131zland\u0131. Yerbilimcilerin yapt\u0131\u011f\u0131 \u00e7al\u0131\u015fmaya g\u00f6re Yer \u00f6ze\u011finden d\u0131\u015far\u0131 akan \u0131s\u0131ya a\u015fa\u011f\u0131daki s\u00fcre\u00e7ler katk\u0131da bulunur:<\/p>\n

1) \u0130\u00e7 \u00f6ze\u011fin kat\u0131la\u015fmas\u0131 sonucu ortaya \u00e7\u0131kan gizli (latent) \u0131s\u0131. 2) \u00d6ze\u011fin so\u011fumas\u0131. 3) D\u0131\u015f \u00f6ze\u011fin s\u00fcperdoyuma ula\u015fmas\u0131 sonucu oksid\/silikatlar\u0131n kristalle\u015fmesiyle \u00fcretilen \u0131s\u0131. 4) Kat\u0131la\u015fma s\u00fcresince Yer \u00f6ze\u011finin b\u00fcz\u00fclmesinin gizilg\u00fc\u00e7 (potansiyel) erkesi ve kristalle\u015fen hafif kat\u0131 cisimlerin \u00f6zek-manto s\u0131n\u0131r\u0131na (CMB: core mantle boundary) y\u00fckselmesi. 5) 40<\/sup>K\u2019n\u0131n bozunmas\u0131yla \u00fcretilen \u0131s\u0131. 6) Uranyumun bozunmas\u0131yla \u00fcretilen \u0131s\u0131. 7) 123<\/sup>Te, 187<\/sup>Re, 186<\/sup>Os elementlerinin bozunmas\u0131yla \u00fcretilen \u0131s\u0131.<\/p>\n

Bu kaynaklara ek olarak Yer\u2019in \u00f6ze\u011finde h\u0131zl\u0131 \u00fcretken reakt\u00f6r bulundu\u011fu sav\u0131 da geli\u015ftirilmi\u015ftir. Herndon (1980, 1993, 2005) ve Hollenbach ve Herndon (2001) Yer\u2019in \u00f6ze\u011finin d\u0131\u015f k\u0131s\u0131mlar\u0131ndaki konveksiyonun ve Yer manyetik alan\u0131n\u0131n s\u00fcreklili\u011fi i\u00e7in \u00f6zekte \u00f6nemli niceliklerde \u0131s\u0131sal erke \u00fcretilmesi gerekti\u011fine i\u015faret ediyorlar. Yazarlar, \u00f6zekte bulunan yo\u011fun uranyum yumaklar\u0131n\u0131n, h\u0131zl\u0131 \u00fcretken reakt\u00f6r (fast breeder reactor) i\u015flevi g\u00f6rerek bu erke kayna\u011f\u0131na b\u00fcy\u00fck katk\u0131da bulunaca\u011f\u0131n\u0131 savunuyor.<\/p>\n

Laboratuvarlarda Yer \u00f6ze\u011findeki bas\u0131nca yak\u0131n ko\u015fullar alt\u0131nda yap\u0131lan deneyler, bir lithophile element olan potasyumun 60-260 mg\/L (Litrede miligram) aras\u0131 yo\u011funluklarda Yer \u00f6ze\u011fine s\u0131zabilece\u011fini g\u00f6sterdi. Son zamanlarda yap\u0131lan bir ba\u015fka deneyde, Yer \u00f6ze\u011findeki s\u0131cakl\u0131k ve bas\u0131n\u00e7 alt\u0131nda uranyumun potasyum gibi davranaca\u011f\u0131 g\u00f6sterildi. Bu deneyler, uranyumun da potasyum gibi davran\u0131p Yer \u00f6ze\u011finde 1-6 mg\/L yo\u011funluklarda bulunabilece\u011fi izlenimi b\u0131rak\u0131yor. Wheeler ve arkada\u015flar\u0131 (2006) \u201cDeney ko\u015fullar\u0131m\u0131z alt\u0131nda uranyumun metal s\u00fclfidden silikata transferi tam olarak ger\u00e7ekle\u015fti\u011finden, geriye yetersiz niceliklerde uranyum kal\u0131r ki, bu da Yer \u00f6ze\u011finin \u0131s\u0131 b\u00fct\u00e7esi i\u00e7in \u00f6nemsizdir\u201d saptamas\u0131n\u0131 yap\u0131yor. Bao ve arkada\u015flar\u0131n\u0131n (2005) deneyi, y\u00fcksek bas\u0131n\u00e7 alt\u0131nda silikonun y\u00fczde 1-2 denlisinin, volkanik bir kaya olan ve y\u00fczde 45 denlisi silis, \u00f6nemli oranlarda magnezyum ve daha az oranlarda demir i\u00e7eren peridotite ile birlikte bulunan s\u0131v\u0131 demir ortam\u0131nda metal evresine ge\u00e7ti\u011fini ve metalik evrede bulunan uranyum konsantrasyonunun da bas\u0131n\u00e7la artt\u0131\u011f\u0131n\u0131 g\u00f6stermi\u015ftir. Uranyumun Yer \u00f6ze\u011fine s\u0131zd\u0131\u011f\u0131n\u0131 varsayal\u0131m. Uranyumun ayr\u0131 bir faz olan kristalizasyonunu hangi s\u00fcre\u00e7 sa\u011flar? 100 kg\u2019dan fazla konsantrasyonlara ula\u015fan uranyum hangi s\u00fcre\u00e7le h\u0131zl\u0131 \u00fcretken reakt\u00f6r gibi davran\u0131r? Bu reakt\u00f6r\u00fcn etkinli\u011fini azaltacak olan yan \u00fcr\u00fcnler zaman zaman dif\u00fczyon yoluyla \u00f6zek d\u0131\u015f\u0131na at\u0131labilir mi?<\/p>\n

\"\"
J. M. Herndon Yer\u2019in \u00f6ze\u011finin d\u0131\u015f k\u0131s\u0131mlar\u0131ndaki konveksiyonun ve Yer manyetik alan\u0131n\u0131n s\u00fcreklili\u011fi i\u00e7in \u00f6zekte \u00f6nemli niceliklerde \u0131s\u0131sal erke \u00fcretilmesi gerekti\u011fine i\u015faret etmi\u015fti.<\/figcaption><\/figure>\n

Yer\u2019in kimyasal bile\u015fiminin yeniden olu\u015fturulma \u00e7abalar\u0131 belli meteoritler, genellikle kondritik meteoritler temelinde yap\u0131l\u0131r, \u00e7\u00fcnk\u00fc ola\u011fan kondritler en s\u0131k kar\u015f\u0131la\u015f\u0131lan meteoritlerdir. Herndon bu varsay\u0131m\u0131n yanl\u0131\u015f oldu\u011funu ve Yer\u2019in daha ender bir meteorit t\u00fcr\u00fc olan enstatite kondritlerinden olu\u015ftu\u011funu savunur.<\/p>\n

 <\/p>\n

 <\/p>\n

Jeolojik tarih boyunca Yer \u00f6ze\u011finin ba\u015fl\u0131ca \u0131s\u0131t\u0131lma ve so\u011fuma a\u015famalar\u0131 <\/strong>(Schuiling, 2006)<\/h3>\n

\u00a0<\/strong><\/p>\n

Is\u0131t\u0131lma a\u015famalar\u0131<\/strong><\/p>\n

1) G\u00fcne\u015f dizgesini olu\u015fturan bulutsunun so\u011fumas\u0131 ve ate\u015fe dayan\u0131kl\u0131 (refractory) elementlerin yo\u011funla\u015fmas\u0131. Yo\u011funla\u015fman\u0131n son s\u0131cakl\u0131\u011f\u0131 yakla\u015f\u0131k 1200 K\u2019dir; bu de\u011fer, ate\u015fe dayan\u0131kl\u0131 elementlerin tamamen yo\u011funla\u015ft\u0131\u011f\u0131 ve ate\u015fe daha az dayan\u0131kl\u0131 elementlerin (volatile) k\u0131smen yo\u011funla\u015fma s\u0131cakl\u0131klar\u0131 dikkate al\u0131narak hesaplanm\u0131\u015ft\u0131r.<\/p>\n

2) Yo\u011funla\u015fm\u0131\u015f olan elementlerin Yer-\u00f6ncesi ortama y\u0131\u011f\u0131lmalar\u0131. Yer \u00f6ze\u011findeki \u00f6zde\u011fin s\u0131k\u0131\u015fmas\u0131 sonucunda s\u0131cakl\u0131\u011f\u0131n artmas\u0131 ve Yer\u2019e \u00e7arpan cisimlerden ve k\u0131sa \u00f6m\u00fcrl\u00fc radyojenik elementlerden gelen erke. S\u0131cakl\u0131k h\u0131zla ~ 2000\u2019e dek \u00e7\u0131kar (d\u00fc\u015f\u00fck bas\u0131n\u00e7larda demirin erime noktas\u0131).<\/p>\n

3) Yer\u2019in \u00fcst katmanlar\u0131nda demir erimeye ba\u015flar (demirin erimesi yerel olarak asteroid \u00e7arp\u0131\u015fmalar\u0131yla tetiklenir) ve metal ma\u011fma \u00e7\u00f6kmeye ba\u015flar.<\/p>\n

4) Yitirilen gizilg\u00fc\u00e7 erkesi \u0131s\u0131ya d\u00f6n\u00fc\u015f\u00fcr. Tortula\u015fman\u0131n (segregation) tamamlanmas\u0131yla bu \u0131s\u0131 t\u00fcm Yer i\u00e7in 1600 K\u2019e denk olur, ancak bu t\u00fcr \u0131s\u0131nman\u0131n \u00e7o\u011fu Yer\u2019in derin katmanlar\u0131nda ger\u00e7ekle\u015fir. Bu derinliklerdeki h\u0131zl\u0131 tortula\u015fma sonucunda s\u0131cakl\u0131k \u00f6nemli \u00f6l\u00e7\u00fclerde artar. \u00d6zek-manto s\u0131n\u0131r\u0131ndaki\u00a0 bas\u0131n\u00e7larda mantodaki \u00f6zde\u011fin erime noktas\u0131 yakla\u015f\u0131k 3800 K\u2019dir. \u00d6zek-manto tortula\u015fmas\u0131n\u0131n tamamlanma a\u015famas\u0131nda bu s\u0131cakl\u0131k, b\u00fcy\u00fck bir olas\u0131l\u0131kla, 3800 K\u2019den daha y\u00fcksekti.<\/p>\n

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So\u011fuma a\u015famalar\u0131<\/strong><\/p>\n

5) Tortula\u015fmadan sonra arda kalan s\u00fcper \u0131s\u0131, alt manto kat\u0131la\u015f\u0131ncaya dek t\u00fcm mantodaki s\u0131v\u0131 konveksiyon taraf\u0131ndan h\u0131zla da\u011f\u0131t\u0131ld\u0131.<\/p>\n

6) Sonra s\u0131v\u0131 konveksiyon nedeniyle \u00f6zekte yava\u015f (ancak g\u00fcn\u00fcm\u00fczdeki so\u011fuma h\u0131z\u0131ndan daha h\u0131zl\u0131 olarak) bir so\u011fuma d\u00f6nemi ba\u015flad\u0131. Bu arada, t\u00fcm mantonun kat\u0131 konveksiyonu ve\/veya \u00f6zek-manto s\u0131n\u0131r\u0131ndan y\u00fckselen f\u0131\u015fk\u0131rmalarla manto da \u0131s\u0131 iletkenli\u011fi yoluyla so\u011fudu. \u00d6nemli \u0131s\u0131 yitikleri, bir plakan\u0131n di\u011ferinin alt\u0131na girdi\u011fi yer ve bu plakalarda ger\u00e7ekle\u015fen su yitimi (dehydration) ve karbon yitimi (decarbonation) gibi \u0131s\u0131 gerektiren (endothermic) tepkimelerdir.<\/p>\n

7) \u00d6zekteki ve mantodaki s\u0131cakl\u0131k, kat\u0131 i\u00e7 \u00f6ze\u011fin olu\u015fmaya ba\u015flayaca\u011f\u0131 noktaya d\u00fc\u015fer. Ba\u015flang\u0131\u00e7ta, kristalle\u015fme s\u0131n\u0131r \u0131s\u0131s\u0131 (latent heat) \u00f6ze\u011fin \u0131s\u0131 b\u00fct\u00e7esine \u00e7ok az katk\u0131da bulunur. Bu a\u015famada \u00f6zekteki \u0131s\u0131 \u00fcretimi ba\u015fl\u0131ca (g\u00fcn\u00fcm\u00fczdekinden daha fazla olarak) 40<\/sup>K (ve uranyum?) dan gelirken, \u00f6zek so\u011fuma yoluyla da \u0131s\u0131 yitirir.<\/p>\n

8) G\u00fcn\u00fcm\u00fczde: 40<\/sup>K\u2019dan \u00fcretilen \u0131s\u0131 olduk\u00e7a azalm\u0131\u015ft\u0131r (Yer\u2019in olu\u015ftu\u011fu d\u00f6nemlerdekinden 10 kat daha az) ve g\u00fcn\u00fcm\u00fczde \u00fcretilen \u0131s\u0131n\u0131n b\u00fcy\u00fck b\u00f6l\u00fcm\u00fc \u00f6ze\u011fin kat\u0131la\u015fmas\u0131 s\u0131ras\u0131nda \u00fcretilen s\u0131n\u0131r \u0131s\u0131d\u0131r. T\u00fcm \u00f6zekteki ve mantonun derinliklerindeki s\u0131cakl\u0131k, kat\u0131 \u00f6ze\u011fin ilk olu\u015fumundan bu yana 170 K ve tortula\u015fman\u0131n tamamlanmas\u0131ndan sonra da 500 K\u2019den daha fazla d\u00fc\u015fme g\u00f6stermi\u015ftir.<\/p>\n

 <\/p>\n

Herndon Hipotezi: Yer \u00f6ze\u011findeki uranyum <\/em><\/strong><\/p>\n

Yer\u2019deki toplam uranyum niceli\u011fi yakla\u015f\u0131k 9\u00b4109 <\/sup>g kadard\u0131r. Bu niceli\u011fin yar\u0131dan biraz fazlas\u0131 Yer kabu\u011fundad\u0131r. \u00dcst mantodaki uranyum konsantrasyonu da yakla\u015f\u0131k 10 ppb (milyarda bir – part per billion) denlidir. Bu durumda mantonun alt b\u00f6l\u00fcmlerindeki + \u00f6zekteki uranyum niceli\u011finin maksimum de\u011feri yakla\u015f\u0131k olarak 3\u00b4109 <\/sup>g kadard\u0131r (Herndon, 1993, \u00f6zek + alt mantodaki uranyum niceli\u011finin 1\u00b4109 <\/sup>g denli oldu\u011funu varsay\u0131yor). Uranyumun lithophile karakteri nedeniyle t\u00fcm mantoya payla\u015ft\u0131r\u0131l\u0131rsa, t\u00fcm mantodaki uranyum konsantrasyon de\u011ferinin ~ 10 ppb olaca\u011f\u0131na inan\u0131l\u0131yor. Ancak e\u011fer, Herndon\u2019un kavramlar\u0131yla, endo \u2013 Yer\u2019deki uranyum Yer\u2019in \u00f6ze\u011fine \u00e7ok etkin bir bi\u00e7imde payla\u015ft\u0131r\u0131l\u0131rsa \u00f6zekteki uranyumun ortalama konsantrasyon de\u011feri kuramsal maksimum de\u011ferine, 15 ppb\u2019ye eri\u015febilir (Malavergne ve arkada\u015flar\u0131na g\u00f6re, 2005, bu de\u011fer 1-6 ppb). Bu de\u011fer, 3\u00b41013<\/sup> ton gibi devasa bir niceli\u011fe denktir. Ancak sorun, bu uranyum da\u011f\u0131l\u0131m\u0131n\u0131 > 100 kg\u2019l\u0131k saf uranyum yumaklar\u0131na d\u00f6n\u00fc\u015ft\u00fcr\u00fcp h\u0131zl\u0131 \u00fcretken reakt\u00f6r gibi etki edebilecek s\u00fcrecin ne olabilece\u011finde yat\u0131yor.<\/p>\n

\"\"
Dr. Helen Caldicott Avustralyal\u0131 bir \u00e7ocuk doktoru.<\/figcaption><\/figure>\n

\u0130lkesel olarak bu maden (ore) olu\u015fum sorunu olarak incelenebilir. Maden olu\u015fumu bir dizi s\u00fcre\u00e7lerin toplam\u0131d\u0131r: d\u00fc\u015f\u00fck konsantrasyonlu bir element b\u00fcy\u00fck oyluma sahip bir kayadan s\u0131zarak daha k\u00fc\u00e7\u00fck oylumlu bir kayaya ta\u015f\u0131n\u0131r ve orada y\u00fcksek konsantrasyonlarda (madencilerin kavramlar\u0131yla y\u00fcksek derecede – grade) depolan\u0131r. Maden olu\u015fum s\u00fcre\u00e7lerinin \u00e7o\u011fu, kimyasal gizilg\u00fc\u00e7te, bas\u0131n\u00e7ta ve s\u0131cakl\u0131kta, \u00e7\u00f6z\u00fcc\u00fclerin (solvent) kaynamas\u0131, dengede bulunmayan iki farkl\u0131 ak\u0131\u015fkan\u0131n kar\u0131\u015f\u0131m\u0131 veya erimi\u015f olan elementin so\u011fumas\u0131 ve kristalle\u015fmesi s\u0131ras\u0131nda ortaya \u00e7\u0131kan keskin uzay de\u011fi\u015fimleriyle (gradyentlerle) ili\u015fkilidir. Bir ak\u0131\u015fkanda y\u00fczen kristaller, e\u011fer ortamdan daha a\u011f\u0131rsa dibe \u00e7\u00f6kecek, hafifse y\u00fczecektir.<\/p>\n

Maden olu\u015fum s\u00fcreci bazen \u00f6nceden zenginle\u015fme a\u015famas\u0131 ge\u00e7irir ve protore olu\u015fur. Protore, daha sonra maden deposu olacak olan bile\u015fenle zenginle\u015fmi\u015f olan bir kaya oylumudur. Kimyasal gizilg\u00fc\u00e7te, bas\u0131n\u00e7 ve s\u0131cakl\u0131kta olu\u015facak olan bir keskin uzay de\u011fi\u015fiminin ak\u0131\u015fkan metalik \u00f6zekte uzun s\u00fcre var olabilme olas\u0131l\u0131\u011f\u0131 olduk\u00e7a d\u00fc\u015f\u00fckt\u00fcr. Di\u011fer yandan, her ne kadar kar\u0131\u015f\u0131ma u\u011framayan (immiscible) silikat ve metal eriyikler tortula\u015fma s\u00fcrecinden sorumlu olsalar da, uranyumun birbirine kar\u0131\u015fmayan iki farkl\u0131 ak\u0131\u015fkan\u0131n olu\u015fturdu\u011fu rezervuarlar aras\u0131nda depolanaca\u011f\u0131n\u0131 d\u00fc\u015f\u00fcnmek olduk\u00e7a zordur.<\/p>\n

Metal-metal s\u00fclfid eriyikte 10 ppb veya daha d\u00fc\u015f\u00fck konsantrasyonlarda erimi\u015f olan uranyumun ayr\u0131 bir evrede kristalle\u015fip Yer\u2019in \u00f6ze\u011fine \u00e7\u00f6kmesi olas\u0131 m\u0131? Uranyumun demire k\u0131yasla daha y\u00fcksek erime s\u0131cakl\u0131\u011f\u0131na sahip oldu\u011funu varsayan Herndon (1993) bunun dolays\u0131z bir \u00f6nerme oldu\u011funu savunsa da, bu \u00f6nerme do\u011fru de\u011fil. D\u00fc\u015f\u00fck bas\u0131n\u00e7lar alt\u0131nda uranyumun erime s\u0131cakl\u0131\u011f\u0131 demirinkinden daha d\u00fc\u015f\u00fck de\u011ferlerdedir. Uranyumun erime noktas\u0131n\u0131n, bas\u0131nc\u0131n bir i\u015flevi olarak, demirinkinden daha h\u0131zl\u0131 y\u00fckseldi\u011fini varsaysak bile, \u00f6zekte kristalle\u015fecek olan ilk metalin uranyum olaca\u011f\u0131 sonucu \u00e7\u0131kar\u0131lamaz. UO2<\/sub>-Fe dizgesinin evre \u00e7izgesine bakarsak (Feber ve ark., 1984) Yer \u00f6ze\u011finde beklenen bile\u015fim (yakla\u015f\u0131k y\u00fczde 80 Fe ve 10 ppb U, konsantrasyon oran\u0131 100 milyon) \u00e7izgenin en sa\u011f\u0131nda, erimi\u015f demir b\u00f6lgesindedir ve bu b\u00f6lgede y\u00fczde 1-2 UO2 \u2013 x <\/sub>bulunur. (\u0130lgin\u00e7tir ki, Feber ve arkada\u015flar\u0131n\u0131n \u00f6zekteki k\u00fctle ve onun i\u00e7indeki demir niceli\u011fi i\u00e7in verdikleri de\u011ferler ger\u00e7ek de\u011ferlerden 1000 kat daha d\u00fc\u015f\u00fckt\u00fcr). Feber ve arkada\u015flar\u0131n\u0131n evre \u00e7izgesine g\u00f6re (\u015eekil 1) bu eriyikteki uranyumun \u00e7\u00f6z\u00fclebilirli\u011fi y\u00fczde 1-2 denlidir, di\u011fer bir deyi\u015fle, 15 ppb\u2019den milyon kez daha b\u00fcy\u00fckt\u00fcr. K\u0131sacas\u0131, uranyum bu denli d\u00fc\u015f\u00fck konsantrasyonlarda ayr\u0131 bir evrede asla kristalle\u015femeyecektir. Metal olarak ilk kristalle\u015fen elementin uranyum olmas\u0131 durumunda bile, uranyumun Yer\u2019in \u00f6ze\u011fine yerle\u015fmesi i\u00e7in bir neden yok, \u00e7\u00fcnk\u00fc Yer \u00f6ze\u011finde \u00e7ekim kuvveti s\u0131f\u0131rd\u0131r.<\/p>\n

Bu durumda, Yer \u00f6ze\u011finde uranyum metalinin dolays\u0131z olarak kristalle\u015fmesi imkans\u0131zd\u0131r sonucunu \u00e7\u0131karmam\u0131z gerekir. \u015eimdi Herndon\u2019un hipotezinin ikinci b\u00f6l\u00fcm\u00fcne bakal\u0131m: Uranyum b\u00fcy\u00fck niceliklere sahip yumaklar bi\u00e7iminde olu\u015ftuktan sonra, s\u00fcrekli olarak bir n\u00fckleer reakt\u00f6r olu\u015fturacak usa yatk\u0131n bir s\u00fcre\u00e7 var m\u0131? Bir an i\u00e7in Yer \u00f6ze\u011finde kat\u0131 uranyum tanecikleri veya y\u00fczen uranyum s\u00fclfidlerin oldu\u011funu d\u00fc\u015f\u00fcnelim; bu durum \u00e7ok u\u00e7uk spek\u00fclasyonlar\u0131 gerektirir ve Herndon\u2019un s\u00f6z\u00fcn\u00fc etti\u011fi gibi bir durum ortaya \u00e7\u0131kabilir. Daha sonra, i\u00e7 \u00f6ze\u011fin d\u0131\u015f k\u0131s\u0131mlar\u0131nda konvektif devinimlerde bulunan ak\u0131\u015fkandaki uranyum taneciklerinin, t\u0131pk\u0131 nehir yataklar\u0131nda tuzaklanan alt\u0131n gibi, tuzakland\u0131\u011f\u0131n\u0131 d\u00fc\u015f\u00fcnebiliriz. Bu tamamen spek\u00fclasyon olsa da en az\u0131ndan dikkate al\u0131nmas\u0131 gereken zay\u0131f bir olas\u0131l\u0131kt\u0131r.<\/p>\n

H\u0131zl\u0131 \u00fcretken reakt\u00f6r\u00fcn \u00fc\u00e7\u00fcnc\u00fc a\u015famas\u0131, yani reakt\u00f6rdeki yan \u00fcr\u00fcnlerin bir s\u0131zma (dif\u00fczyon) s\u00fcreciyle reakt\u00f6rden uzakla\u015ft\u0131r\u0131lmas\u0131n\u0131n \u00f6n\u00fcnde a\u015f\u0131lmas\u0131 zor g\u00fc\u00e7l\u00fckler vard\u0131r. Uranyum, nikel-demirden daha a\u011f\u0131r oldu\u011fu i\u00e7in uranyum konsantrasyonu giderek b\u00fcy\u00fcyen i\u00e7 \u00f6zekte yerle\u015fecek ve bir sonraki kat\u0131 nikel-demir katmanda hapsedilecektir. Reakt\u00f6rde \u00fcretilen yan \u00fcr\u00fcnlerin kat\u0131 bir ortamdan d\u0131\u015far\u0131 s\u0131zma oran\u0131 (helyum hari\u00e7), s\u0131cakl\u0131k 4000 K de olsa, son derece d\u00fc\u015f\u00fckt\u00fcr. K\u0131sacas\u0131, reakt\u00f6r etkinli\u011fini d\u00fc\u015f\u00fcrecek olan yan \u00fcr\u00fcnleri son derece etkin bir ta\u015f\u0131n\u0131m s\u00fcreciyle reakt\u00f6rden uzakla\u015ft\u0131racak bir s\u00fcre\u00e7 bulunmad\u0131k\u00e7a, \u00fcretken reakt\u00f6r\u00fcn kendi kendini etkisizle\u015ftirmesi a\u015f\u0131lamaz bir engel olarak duracakt\u0131r.<\/p>\n

Bu a\u015famada, n\u00fckleer reakt\u00f6rlerdeki yak\u0131tlar\u0131 etkisizle\u015ftiren s\u00fcrece ve n\u00fckleer reakt\u00f6rlere kar\u015f\u0131 ya\u015fam\u0131 boyunca sava\u015f\u0131m veren ve insanl\u0131\u011f\u0131 ayd\u0131nlatan Dr. Helen Caldicott\u2019\u0131n uyar\u0131lar\u0131na k\u0131saca de\u011finelim.<\/p>\n

 <\/p>\n

N\u00fckleer reakt\u00f6rleri etkisizle\u015ftiren izotoplar<\/em><\/strong><\/p>\n

Dr. Helen Caldicott Avustralyal\u0131 bir \u00e7ocuk doktoru ve \u00fc\u00e7 \u00e7ocuk annesi. Ya\u015fam\u0131n\u0131 Cystic Fibrosis<\/em> ad\u0131 verilen ve kendisini daha \u00e7ok pankreas enzimlerinin yetmezli\u011fi, solunum yetmezli\u011fi ve terleme yoluyla su yitirilmesi bi\u00e7iminde g\u00f6steren hastal\u0131ktan k\u0131vranan \u00e7ocuklar\u0131n sa\u011falt\u0131m\u0131na adam\u0131\u015f bir insan. Solunum yetmezli\u011finden, l\u00f6semi ve kat\u0131 kanser t\u00fcrlerinden \u00f6len hastalar\u0131, Dr. Helen Caldicott\u2019\u0131 kamu \u00f6n\u00fcnde a\u00e7\u0131k\u00e7a konu\u015fmaya ve Nuclear Madness<\/em> adl\u0131 kitab\u0131 yazmaya itmi\u015f. Bu t\u00fcr genetik hastal\u0131klar\u0131n ve bozukluklar\u0131n nedeninin gezegenimizi kirleten radyoaktif elementler oldu\u011funu bildi\u011finden suskun kalamam\u0131\u015f.<\/p>\n

\u201cYer\u2019deki uranyum madenlerinden \u00e7\u0131kar\u0131lan her bir ton uranyum cevherinden 2 kg saf uranyum elde edilir. Bu niceli\u011fin y\u00fczde 99,3 kadar\u0131 fizyona giremeyen uranyum-238 izotopudur. 2 kg\u2019\u0131n yaln\u0131zca 14 gram\u0131 fizyona girebilen uranyum-235\u2019dir. Ticari reakt\u00f6rlerin \u00e7o\u011funda kullan\u0131lan fizyon s\u00fcreci i\u00e7in U-235\u2019in \u00f6zg\u00fcn bir minimum niceli\u011fe sahip olmas\u0131 gerekir. Do\u011fal olarak elde edilen uranyumun yaln\u0131zca y\u00fczde 0,7\u2019si i\u015fe yarar U-235 oldu\u011fundan uranyum cevherinin \u2018zenginle\u015ftirilmesi\u2019 gerekir. B\u00f6ylece fizyonda kullan\u0131lan yakla\u015f\u0131k y\u00fczde 3 oran\u0131ndaki U-235 elde edilmi\u015f olur.<\/p>\n

\u201cZenginle\u015ftirme s\u00fcrecini ge\u00e7en uranyum (UO2<\/sub> – uranyumoksit olarak) hap bi\u00e7imine getirilir. Silindirik haplar daha sonra boyu 3,5-4 m, \u00e7ap\u0131 da 2 cm olan silindir bi\u00e7imindeki metal yak\u0131t \u00e7ubuklar\u0131na yerle\u015ftirilir. 1000 megawatl\u0131k bir reakt\u00f6rde yakla\u015f\u0131k 50.000 yak\u0131t \u00e7ubu\u011fu vard\u0131r. \u00c7ap\u0131 6 m y\u00fcksekli\u011fi de 4 m olan silindir bi\u00e7imindeki bir oylumda 100 ton uranyum bulunur.<\/p>\n

\u201cYak\u0131t \u00e7ubuklar\u0131 n\u00fckleer reakt\u00f6r\u00fcn \u00f6ze\u011fine yerle\u015ftirildikten ve su ile kapland\u0131ktan sonra zenginle\u015ftirilmi\u015f uranyum fizyona haz\u0131r demektir. Fizyon s\u00fcrecine giren U-235 atomunun \u00e7ekirde\u011fi par\u00e7alar\u0131na ayr\u0131l\u0131r. Bunlara fizyon \u00fcr\u00fcnleri de denir: Strontium veya Sezyum gibi daha hafif elementlerin \u00e7ekirdekleri olu\u015fur. Bu par\u00e7alanma s\u0131ras\u0131nda \u0131s\u0131 ile bir veya birka\u00e7 n\u00f6tron \u00f6zg\u00fcr duruma ge\u00e7er. Her bir \u00e7ekirde\u011fin par\u00e7alanmas\u0131 sonucunda ortaya \u00e7\u0131kan n\u00f6tronlar di\u011fer atom \u00e7ekirdeklerini par\u00e7alar. \u00d6zg\u00fcr n\u00f6tronlar\u0131n her biri uranyum atomlar\u0131nca so\u011furulup yerine par\u00e7alanan di\u011fer atomlardan sal\u0131nan n\u00f6tronlar ge\u00e7meye ba\u015flay\u0131nca reakt\u00f6r \u2018kritik\u2019 a\u015famaya gelir. Bu zincirleme tepkime art\u0131k kendi kendini destekler duruma gelmi\u015ftir. H\u0131zl\u0131 devinen n\u00f6tronlar\u0131 so\u011furan denetleme \u00e7ubuklar\u0131 s\u00fcrecin h\u0131z\u0131n\u0131 ayarlar.<\/p>\n

\u201cFizyon dev boyutlarda \u0131s\u0131 salar. Bu \u0131s\u0131 suyun buharla\u015fmas\u0131nda kullan\u0131l\u0131r. Buhar t\u00fcrbinleri \u00e7al\u0131\u015ft\u0131r\u0131r ve elektrik \u00fcretilir. K\u0131sacas\u0131, n\u00fckleer fizyon suyu kaynatman\u0131n \u00e7ok ince ve son derece pahal\u0131 bir yoludur, t\u0131pk\u0131 elektrikli b\u0131\u00e7akla tereya\u011f\u0131 kesmek gibi bir \u015fey! Uranyum fizyonu elektrik \u00fcretmenin yan\u0131 s\u0131ra y\u00fczlerce radyoaktif izotop da ortaya \u00e7\u0131kar\u0131r. Bu izotoplar\u0131n yar\u0131 \u00f6m\u00fcrleri birka\u00e7 saniye ile 24.400 y\u0131la dek de\u011fi\u015fir ve hepsi de hem kansere hem de genetik mutasyona neden olur.<\/p>\n

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\u015eekil 1. UO2-Fe dizgesinin evre \u00e7izgesi (Schuiling, 2006).<\/figcaption><\/figure>\n

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\u201cN\u00fckleer teknoloji uzmanlar\u0131 pl\u00fctonyuma n\u00fckleer erke \u00fcretiminde kullan\u0131lan uranyum-235\u2019in yede\u011fi g\u00f6z\u00fcyle bak\u0131yor. D\u00fcnyadaki uranyum-235 kaynaklar\u0131 t\u00fckendi t\u00fckenecek. Uranyum-235\u2019e olan gereksinimi ortadan kald\u0131rmay\u0131 ama\u00e7layan n\u00fckleer end\u00fcstri h\u0131zl\u0131 \u00fcretken reakt\u00f6r\u00fc tasarlad\u0131. Bu reakt\u00f6r\u00fcn yak\u0131t\u0131, pl\u00fctonyum ile uranyum-238\u2019in birlikteli\u011fidir. \u2018\u00dcretken\u2019 olarak adland\u0131r\u0131lmas\u0131n\u0131n nedeni, elektrik \u00fcretme s\u00fcrecinde reakt\u00f6r t\u00fcketti\u011finden daha fazla pl\u00fctonyum \u00fcretir. Fransa\u2019n\u0131n Super-Phonix ad\u0131 verilen h\u0131zl\u0131 \u00fcretken reakt\u00f6r\u00fc ba\u015flang\u0131\u00e7taki pl\u00fctonyum yak\u0131t\u0131n\u0131 60 y\u0131lda ikiye katlayacakt\u0131r.<\/p>\n

\u201cGelece\u011fin h\u0131zl\u0131 reakt\u00f6rlerine yak\u0131t olu\u015fturacak olan pl\u00fctonyum bug\u00fcn depo tanklar\u0131nda yatan kullan\u0131lm\u0131\u015f yak\u0131t \u00e7ubuklar\u0131ndad\u0131r. Ancak, h\u0131zl\u0131 reakt\u00f6rlerde kullan\u0131labilmesi i\u00e7in yak\u0131t \u00e7ubuklar\u0131nda fizyonun di\u011fer yan \u00fcr\u00fcnleriyle kar\u0131\u015fm\u0131\u015f bulunan pl\u00fctonyumun \u2018ay\u0131klanmas\u0131\u2019 gerekir. Bunun i\u00e7in yak\u0131t \u00e7ubuklar\u0131 birka\u00e7 ay s\u00fcreyle so\u011fumaya al\u0131n\u0131r; b\u00f6ylece k\u0131sa \u00f6m\u00fcrl\u00fc radyoaktif elementlerin bozunmas\u0131n\u0131n tamamlanmas\u0131 sa\u011flan\u0131r. \u2018S\u0131cak\u2019 \u00e7ubuklar daha sonra kal\u0131n kur\u015fun kasalar i\u00e7inde kamyonlara y\u00fcklenir ve otobanlarda y\u00fczlerce kilometre s\u00fcren yolculu\u011fa \u00e7\u0131karlar. \u2018Yeniden i\u015fleme\u2019 girecekleri istasyonda nitrik asite yat\u0131r\u0131l\u0131rlar. Burada pl\u00fctonyum ve uranyum birbirinden ayr\u0131l\u0131r, saf bi\u00e7ime getirilir ve di\u011fer fizyon \u00fcr\u00fcnlerinden ar\u0131nd\u0131r\u0131l\u0131r. Saf pl\u00fctonyum ve uranyum yine yo\u011fun korumal\u0131 kasalarda h\u0131zl\u0131 reakt\u00f6re do\u011fru yola \u00e7\u0131kar.\u201d<\/p>\n

N\u00fckleer end\u00fcstriye kar\u015f\u0131 verdi\u011fi sava\u015f\u0131m Dr. Helen Caldicott\u2019a \u00e7ok \u015fey \u00f6\u011fretmi\u015f; ancak bunlardan ikisi olduk\u00e7a \u00f6nemli: Birincisi, ya\u015famlar\u0131m\u0131z\u0131, gelecek nesillerin ya\u015famlar\u0131n\u0131, sa\u011fl\u0131\u011f\u0131m\u0131z\u0131 art\u0131k cahil politikac\u0131lar\u0131n, sat\u0131l\u0131k b\u00fcrokratlar\u0131n, \u201cuzmanlar\u0131n\u201d veya bilimsel uzmanlar\u0131n eline teslim etmekten vazge\u00e7elim. \u00c7\u00fcnk\u00fc, bu s\u0131n\u0131flamadaki insanlar birbirleriyle olan \u00e7eli\u015fkilerini s\u0131k s\u0131k uzla\u015fmayla noktalayabiliyorlar. H\u00fck\u00fcmet yetkililerinin \u00e7o\u011fu n\u00fckleer sava\u015f ve n\u00fckleer end\u00fcstrinin i\u015faret etti\u011fi sa\u011fl\u0131k sorunlar\u0131ndan habersiz olmalar\u0131na kar\u015f\u0131n bu y\u00f6nde her g\u00fcn \u00e7ok say\u0131da karar alabiliyorlar. Dr. Caldicott bu noktada meslekta\u015flar\u0131n\u0131n sorumluluk almadaki isteksiz davran\u0131\u015flar\u0131n\u0131 da ele\u015ftiriyor: \u201c\u00c7o\u011fumuz ara\u015ft\u0131rma laboratuvarlar\u0131n\u0131n, hastane koridorlar\u0131n\u0131n \u00f6tesinde neler olup bitti\u011fiyle ilgilenmezken bir k\u0131sm\u0131m\u0131z\u0131n da n\u00fckleer teknoloji ve radyasyonun kansere neden oldu\u011funu bilmesine kar\u015f\u0131n bu teknolojinin sa\u011fl\u0131\u011f\u0131m\u0131za dayatt\u0131\u011f\u0131 tehlikeler konusunda sessiz kalmas\u0131 anla\u015f\u0131l\u0131r gibi de\u011fil.\u201d \u0130kincisi, insan neslinin t\u00fckenmemesi, her bir bireyin kendi pay\u0131na d\u00fc\u015fen sorumlulu\u011fun bilincinde olmas\u0131yla olas\u0131d\u0131r. Bug\u00fcn fizyon yoluyla erke elde eden teknolojinin yararl\u0131 m\u0131 zararl\u0131 m\u0131 oldu\u011fu konusunda d\u00fcnya \u00e7ap\u0131nda s\u00fcregelmekte olan bir tart\u0131\u015fma var. Her birey, bug\u00fcnden ba\u015flamak \u00fczere, bu teknolojinin sa\u011fl\u0131\u011f\u0131m\u0131za olan tehlikelerini \u00f6\u011frenmelidir; \u00e7\u00fcnk\u00fc ay\u0131rd\u0131na varmad\u0131\u011f\u0131m\u0131z s\u00fcrece bu tehlikeler bizim ya\u015fam\u0131m\u0131za son verebilir.<\/p>\n

Evet, art\u0131k Yer\u2019in dibine girip oradaki varl\u0131\u011f\u0131 baz\u0131lar\u0131nca savlanan ve baz\u0131lar\u0131nca yads\u0131nan h\u0131zl\u0131 \u00fcretken reakt\u00f6rde neler olup bitti\u011fine ili\u015fkin sonuca bakabiliriz.<\/p>\n

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Sonu\u00e7<\/em><\/strong><\/p>\n

Herndon\u2019un uranyumun \u00f6nemli niceliklerde \u00f6ze\u011fe s\u0131zd\u0131\u011f\u0131 ve \u00f6zekte radyoaktif bozunma yoluyla \u00f6nemli niceliklerde \u0131s\u0131 \u00fcretece\u011fi olas\u0131l\u0131\u011f\u0131 yads\u0131namaz. E\u011fer buradaki uranyum daha sonra oldhamite<\/strong> gibi bir mineral taraf\u0131ndan yakalan\u0131rsa \u00f6zek-manto s\u0131n\u0131r\u0131 yak\u0131nlar\u0131nda \u0131s\u0131 \u00fcretiminde yerel anormalliklere neden olabilir ve mantodan f\u0131\u015fk\u0131rmalar\u0131 tetikleyebilir.<\/p>\n

Bir uranyum bile\u015fi\u011finin (compound) veya uranyum metalinin, 15 ppb veya daha az uranyum i\u00e7eren metal-metal s\u00fclfid eriyikte kristalle\u015fmesini ve yeterince b\u00fcy\u00fck niceliklerde konsantrasyonunu sa\u011flay\u0131p h\u0131zl\u0131 \u00fcretken reakt\u00f6r olarak \u00e7al\u0131\u015fmas\u0131n\u0131 sa\u011flayacak usa yatk\u0131n bir s\u00fcre\u00e7 yoktur. Ancak yine de uyan\u0131k olmal\u0131y\u0131z; b\u00f6ylesi bir s\u00fcreci d\u00fc\u015f\u00fcnemiyor olmam\u0131z bu s\u00fcrecin olmad\u0131\u011f\u0131n\u0131n kan\u0131t\u0131 de\u011fildir. Jeon\u00f6trino ak\u0131lar\u0131n\u0131n bize sa\u011flayaca\u011f\u0131 bilgiler ilgin\u00e7 olabilir.<\/p>\n

Yer \u00f6ze\u011finde ek bir \u0131s\u0131 kayna\u011f\u0131 oldu\u011funu varsaymaya gerek yok. Bilinen \u0131s\u0131 kaynaklar\u0131 \u00f6zekten d\u0131\u015far\u0131 akan \u0131s\u0131y\u0131 ve Yer\u2019in manyetik alan\u0131n\u0131 s\u00fcrekli k\u0131lacak erkeyi sa\u011flamak i\u00e7in yeterlidir.<\/p>\n

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KAYNAKLAR<\/strong><\/p>\n

1) Bao, X. ve ark<\/em>., 2005, AGU<\/em> Abstract<\/em><\/p>\n

2) Eisley, L., Darwin\u2019s Century<\/em>, Anchor Books, Doubleday and Company Inc., Garden City, New York, 1961.<\/p>\n

3) Feber, R.C. ve ark<\/em>., 1984, EOS<\/em> 65, 44.<\/p>\n

4) Herndon, J.M., 1980, Proc. R. Soc. Lond. A <\/em>368, 495-500<\/p>\n

5) Herndon, J.M., 1993, J. Geomagn. Geoelectr<\/em>. 45, 423-437<\/p>\n

6) Herndon, J.M., 2005, http:\/\/www.arXiv.org\/physics\/0510090<\/a><\/p>\n

7) Hollenbach, D.F. & Herndon, J.M., Proc. Natl. Acad. Sci. USA<\/em><\/p>\n

http:\/\/en.wikipedia.org\/wiki\/Helen_Caldicott<\/a><\/p>\n

8) Malavergne, V. ve ark<\/em>., 2005, Proceedings Lunar and Planetary Science Conference<\/em>, XXXVI, p.1823.<\/p>\n

9) Schuiling, R.D., \u201cIs there a Nuclear Reactor at the Center of the Earth\u201d, Earth, Moon and Planets<\/em> (2006).<\/p>\n

10) Wheeler, K.T. ve ark<\/em>., 2006, Geochim. Cosmochim. Acta<\/em> 70, 1537-1547.<\/p>\n","protected":false},"excerpt":{"rendered":"

Ba\u015f\u0131n\u0131 Lord Kelvin\u2019in \u00e7ekti\u011fi fizik\u00e7iler, yerbilimcilerin ve Darwin\u2019in Evrim kuram\u0131n\u0131n \u201cs\u0131n\u0131rs\u0131z zaman\u201d ilkesine sava\u015f a\u00e7m\u0131\u015flard\u0131. Darwin\u2019i dahi gerilettiler, ama daha sonra ula\u015f\u0131lan bilimsel ger\u00e7ekler 19. y\u00fczy\u0131l\u0131n k\u00f6t\u00fcmser fizi\u011fini \u00e7\u00fcr\u00fctt\u00fc. G\u00fcn\u00fcm\u00fczde ise ayn\u0131 konuda daha farkl\u0131 bir tart\u0131\u015fma var. Yer\u2019in merkezindeki varl\u0131\u011f\u0131 baz\u0131lar\u0131nca savlanan baz\u0131lar\u0131nca yads\u0131nan h\u0131zl\u0131 \u00fcretken reakt\u00f6rde neler olup bitiyor? Ve bu olup bitenler […]<\/p>\n","protected":false},"author":475,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[109,32,26,232],"tags":[683],"class_list":["post-10325","post","type-post","status-publish","format-standard","hentry","category-72-sayi","category-evrim","category-fizik","category-yerbilimleri","tag-kelvin"],"acf":[],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/bilimvegelecek.com.tr\/index.php\/wp-json\/wp\/v2\/posts\/10325","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/bilimvegelecek.com.tr\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/bilimvegelecek.com.tr\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/bilimvegelecek.com.tr\/index.php\/wp-json\/wp\/v2\/users\/475"}],"replies":[{"embeddable":true,"href":"https:\/\/bilimvegelecek.com.tr\/index.php\/wp-json\/wp\/v2\/comments?post=10325"}],"version-history":[{"count":0,"href":"https:\/\/bilimvegelecek.com.tr\/index.php\/wp-json\/wp\/v2\/posts\/10325\/revisions"}],"wp:attachment":[{"href":"https:\/\/bilimvegelecek.com.tr\/index.php\/wp-json\/wp\/v2\/media?parent=10325"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/bilimvegelecek.com.tr\/index.php\/wp-json\/wp\/v2\/categories?post=10325"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/bilimvegelecek.com.tr\/index.php\/wp-json\/wp\/v2\/tags?post=10325"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}