Shekarun duniya

Yana da, aƙalla na ɗan lokaci, duniyar da take rayuwa a kanta. Yana da tazarar da ta dace da rana don a sami ruwa cikin ruwa da yanayin zafin da zai isar miliyoyin shuke-shuke da dabbobi su girma. Duniya.

Shekaranku nawa? Tafiyarsa ta zama abin da yake a yau ya kasance mai haɗari da haɗari. Wajen waje ba wuri ne mai aminci ba. Amma, Menene shekarun duniya kuma yaya aka lissafta shi?

Shekarun Duniya nawa?

Kodayake babu cikakken adadin, an san duniyarmu da kimanin shekaru biliyan 4.500. Masana ilimin kimiyyar kasa da kimiyyar lissafi sun iya lissafin shekaru ta hanyar auna yawan abubuwan da sinadarin uranium na karfen radiyo ke narkewa cikin gubar. Hakanan, ta amfani da dabarun saduwa da radiometric, sun gano yadda tsoffin meteorites suke, wanda yayi kama da na Duniya da Wata.

Tsohon sanannen ma'adinai shine zirconium daga yankin Jack Hills na Yammacin Ostiraliya. An kiyasta su shekaru miliyan 4.404. Tsoffin meteorites da aka samo a cikin tsarin hasken rana, ma'ana, wadatar wadataccen alli-aluminiya, suna da shekaru miliyan 4.567. Wannan yana nufin cewa Tsarin Rana ya fara samar da shekaru miliyan 4.567 da suka gabata.

Wani hasashe ya nuna cewa Duniya ta fara samuwa ne jim kadan bayan da meteorites suka yi, amma har yanzu ba a iya tantance ainihin shekarun ta ba.

Ka'idojin farko

An daɗe ana tunani cewa duniyar tana nan har abada, har sai masana ilimin halitta suka fara fahimtar canje-canje daban-daban da duniyar tamu ta fuskanta yayin nazarin lamuranta. Nicolas Steno na ɗaya daga cikin farkon waɗanda suka fahimci alaƙar da ke tsakanin burbushin halittu da waɗanda muka ambata ɗazu. A wajajan 1790, Bature masanin halitta William Smith yayi tunanin cewa idan yadudduka biyu na dutse a wasu shafuka daban daban suna dauke da burbushin burbushin halittu, to akwai yiwuwar dukkan matakan biyu sun fito daga lokaci guda. Shekaru daga baya wani dan wa, John Phillips, ya kirga ta amfani da wadannan dabarun cewa shekarun Duniya zasu kai kimanin shekaru miliyan 96.

Masanin halitta Mikhail Lomonosov yayi tunanin cewa Duniya ta samu ne ba tare da sauran halittun ba, shekaru dubu dari da suka gabata. A cikin 1779 ɗan asalin Faransa Bafaranshe Comte Du Buffon ya gudanar da gwaji: ya ƙirƙiri ƙaramar duniyar da abun da ke ciki ya yi kama da na duniyar sannan kuma ya auna yanayin sanyayarsa.. Don haka, ya kiyasta shekarun duniya game da shekaru dubu 75.

Duk da haka, Sai a shekarar 1830 ne wani masanin kasa mai suna Charles Lyell ya ba da shawarar cewa duniya tana canzawa koyaushe. Wannan, kodayake a yau wani abu ne na dabi'a kuma mai ma'ana a gare mu, a wancan lokacin ya kasance wata ka'ida ce ta sabon labari, tunda suna tunanin cewa duniyar wani abu ne mai tsaye, cewa kawai ya canza ta hanyar masifu na halitta.

Lissafi

Jikin jiki na Glasgow William Thomson ya buga a 1862 a lissafin lissafin da aka kiyasta shekarun duniyar mu zuwa tsakanin shekaru miliyan 24 zuwa 400 miliyan. Ubangiji Kelvin, wanda daga baya za a kira shi, ya zaci cewa Duniya ta samu kamar kwalba na narkakken dutsen, kuma ya kirga lokacin da za a yi kafin aikin sanyaya ya kai matsakaicin zafin da yake a yanzu (14ºC). Duk da komai, masana ilimin kasa basu gamsu da cewa wannan tunanin yayi inganci ba.

Charles Darwin, wanda yayi nazarin ayyukan Lyell, ya gabatar da ka'idarsa game da zabin yanayi, tsari ne wanda jerin canje-canje a cikin kwayoyin halitta kuma, tabbas, lokaci ya zama dole su faru.. Saboda haka, yayi tunanin cewa shekaru miliyan 400 basu isa ba.

A cikin 1856 masanin ilmin kimiyyar lissafi dan kasar Jamus Hermann von Helmholt kuma a cikin 1892 masanin tauraron dan adam dan kasar Kanada Simon Newcomb, suka gabatar da nasu lissafin. Na farkon yana da shekaru miliyan 22, na biyu kuma miliyan 18. Masana kimiyya sun isa ga wadannan alkaluman ta hanyar lissafin lokacin da rana zata dauka don juyawa zuwa yadda take a yanzu da kuma tsananinta daga iskar gas da ƙura daga inda ta samu.

Ci gaban sadarwar rediyo

A halin yanzu zamu iya samun ra'ayin yadda tsoffin duwatsu da ma'adinai ke godiya ga saduwa ta rediyo, wanda hanya ce da Arthur Holmes ya kirkira a farkon karni na XNUMX kuma hakan ya dogara ne da gwargwadon isotope da ake kira uba da na ɗaya ko fiye na zuriya waɗanda aka san rabinsu..

Radiotric Dating an fara buga shi a cikin 1907 ta Bertran Boltwood kuma a yau shine babban tushen bayanai game da shekarun duwatsu, ko duniyar Duniya kanta. Akwai hanyoyi daban-daban na saduwa, waɗanda sune:

• Hanyar Carbon 14: Yana da amfani don saduwa a cikin ilimin kimiya na kayan tarihi, ilimin ɗan adam, yanayin ɗabi'a, teku, kimiyyar ƙasa, da ilimin ƙasa.
• Hanyar potassium-argon: ana amfani dashi a geology.
• Rubidium-etrontium hanya: ana amfani dashi a cikin ƙawancen tsoffin duwatsu na duniya da na miestras.
• Hanyoyin Thorium 230: anyi amfani dashi a cikin tsohuwar tsohuwar lalata layin teku.
• Hanyoyin jagora: amfani dashi a geology.

Ta haka ne, Holmes yayi aune-aune akan samfuran dutse kuma a 1911 ya kammala cewa mafi tsufa shine shekaru miliyan 1600.. Amma waɗannan ƙididdigar ba abin dogara ba ne. Shekaru biyu bayan haka, an buga sakamakon da ke nuna cewa abubuwan suna da isotopes, waɗanda suke bambance-bambancen daban-daban tare da talakawa daban-daban. A cikin 30s, an nuna isotopes yana da tsakiya wanda ya kunshi lambobi daban-daban na barbashi tsaka ko neutron.

An yi watsi da aikin Holmes har zuwa 1920s, lokacin da A cikin 1921 a taron shekara-shekara na Britishungiyar Birtaniyya don Ci gaban Ilimin Kimiyya mambobin sun tabbatar da cewa shekarun duniyar nan yearsan shekaru biliyan ne, kuma cewa rawanin rediyo ya kasance abin dogaro. A 1927 ya fitar da aikinsa »The Age of the Earth, Gabatarwa ga Ka'idojin Yanayi inda ya kirga cewa ya kasance tsakanin shekaru miliyan 1600 zuwa 3000.

Kusan 1931 majalisar bincike ta ƙasa, na kwalejin kimiyya ta ƙasa ta Amurka, ta nada kwamiti don gano yadda shekarun Duniya suke. An gayyaci Holmes, kasancewarta ɗaya daga cikin fewan tsirarun mutanen da suka san dabarun saduwa da na'urar rediyo, don yin aiki a kwamitin. Rahoton da suka samar ya bayyana cewa saduwa da radiometric ita ce kadai hanyar da za a iya amfani da ita don tantance jerin lokutan binciken kasa.

A ƙarshe, CC Patterson ya kirga shekarun Duniya a cikin 1956 ta amfani da isotope Dating na uranium gubar lalata jerin meteorites.

Duniyarmu har yanzu tana da miliyoyin shekaru da yawa don rayuwa. Idan a karshe akidar cewa rana zata "hadiye" duniya idan ta juye izuwa jar katuwar jar, za mu iya kusan tabbata cewa har yanzu zata kewaya da tauraruwar sarki kusan shekaru biliyan 5.