Isisindo sekhilogremu singakanani? Ososayensi bebelokhu behlola le nkinga ebonakala ilula amakhulu eminyaka.
Ngo-1795, iFrance yamemezela umthetho owawubeka "igremu" ngokuthi "isisindo esiphelele samanzi ku-cube enomthamo olingana nengxenye eyodwa kweziyikhulu zemitha ekushiseni lapho iqhwa lincibilika (okungukuthi, u-0°C)." Ngo-1799, ososayensi bathola ukuthi umthamo wamanzi uzinzile kakhulu lapho ubuningi bamanzi buphakeme kakhulu ku-4°C, ngakho-ke incazelo yekhilogram ishintshe yaba "yisisindo se-cubic decimeter eyodwa yamanzi ahlanzekile ku-4°C". Lokhu kwakhiqiza ikhilogram yokuqala yeplatinum emsulwa, ikhilogram ichazwa njengelingana nobunzima bayo, obubizwa ngokuthi i-archives kilogram.
Leli kilogram eligciniwe lisetshenziswe njengesilinganiso iminyaka engama-90. Ngo-1889, iNgqungquthela Yokuqala Yamazwe Ngamazwe Yezokulinganisa ivumile ikhophi ye-platinum-iridium alloy eseduze nekhilogremu eligciniwe njengekhilogremu yokuqala yomhlaba wonke. Isisindo "sekhilogremu" sichazwa yi-platinum-iridium alloy (90% platinum, 10% iridium) cylinder, engaba ngu-39 mm ukuphakama nobubanzi, futhi okwamanje igcinwe engaphansi komhlaba emaphethelweni eParis.
Ikhilogremu yokuqala yamazwe ngamazwe
Kusukela eNkathini Yokukhanyiselwa, umphakathi ohlola izinto ubelokhu uzibophezele ekusunguleni uhlelo lokuhlola oluhlanganisa yonke indawo. Nakuba kuyindlela engenzeka yokusebenzisa into ebonakalayo njengesilinganiso sokulinganisa, ngoba into ebonakalayo yonakaliswa kalula yizinto ezenziwe ngumuntu noma ezemvelo, ukuzinza kuzothinteka, futhi umphakathi ohlola izinto ubulokhu ufuna ukuyeka le ndlela ngokushesha okukhulu.
Ngemva kokuba ikhilogremu isebenzise incazelo yekhilogremu yokuqala yomhlaba wonke, kukhona umbuzo okhathaza kakhulu izazi ze-metrology: ingabe le ncazelo izinzile kangakanani? Ingabe izoqhubeka ngokuhamba kwesikhathi?
Kufanele kushiwo ukuthi lo mbuzo waphakanyiswa ekuqaleni kwencazelo yeyunithi yesisindo ikhilogram. Isibonelo, lapho ikhilogram ichazwa ngo-1889, i-International Bureau of Weights and Measures yakhiqiza izisindo zekhilogram eziyi-7 ze-platinum-iridium alloy, enye yazo eyi-International The original kilogram isetshenziselwa ukuchaza iyunithi yesisindo ikhilogram, kanti ezinye izisindo eziyi-6 ezenziwe ngezinto ezifanayo kanye nenqubo efanayo zisetshenziswa njengezilinganiso zesibili zokuhlola ukuthi kukhona yini ukuzulazula ngokuhamba kwesikhathi phakathi komunye nomunye.
Ngesikhathi esifanayo, ngokuthuthukiswa kobuchwepheshe obunembile kakhulu, sidinga nezilinganiso ezizinzile nezinembile kakhudlwana. Ngakho-ke, kwaphakanyiswa uhlelo lokuchaza kabusha iyunithi eyisisekelo yomhlaba wonke ngama-constant angokwenyama. Ukusebenzisa ama-constant ukuchaza amayunithi okulinganisa kusho ukuthi lezi zincazelo zizohlangabezana nezidingo zesizukulwane esilandelayo sokutholwa kwesayensi.
Ngokusho kwedatha esemthethweni ye-International Bureau of Weights and Measures, eminyakeni eyi-100 kusukela ngo-1889 kuya ku-2014, ukuhambisana kwekhwalithi kwamanye amakhilogremu okuqala kanye nekhilogremu yokuqala yamazwe ngamazwe kwashintsha ngama-microgram angaba ngu-50. Lokhu kukhombisa ukuthi kunenkinga ngokuqina kwesilinganiso somzimba seyunithi yekhwalithi. Nakuba ushintsho lwama-microgram angu-50 luzwakala luluncane, lunomthelela omkhulu kwezinye izimboni ezisezingeni eliphezulu.
Uma ama-constant ayisisekelo asetshenziswa esikhundleni se-kilogram physical benchmark, ukuzinza kweyunithi yesisindo ngeke kuthinteke isikhala nesikhathi. Ngakho-ke, ngo-2005, iKomidi Lomhlaba Wonke Lezilinganiso Nezilinganiso labhala uhlaka lokusetshenziswa kwama-constant ayisisekelo ayisisekelo ukuchaza amanye amayunithi ayisisekelo e-International System of Units. Kunconywa ukuthi i-Planck constant isetshenziswe ukuchaza iyunithi yesisindo ikhilogram, futhi amalabhorethri asezingeni likazwelonke anekhono ayakhuthazwa ukuba enze umsebenzi wocwaningo lwesayensi ohlobene.
Ngakho-ke, eNgqungqutheleni Yomhlaba Wonke Yango-2018 Ye-Metrology, ososayensi bavotela ukuyekisa ngokusemthethweni i-prototype kilogram yomhlaba wonke, futhi bashintsha i-Planck constant (uphawu h) njengendinganiso entsha yokuchaza kabusha i-"kg".
Isikhathi sokuthunyelwe: Mashi-05-2021