Isisindo esingakanani ikhilogremu? Sekungamakhulu eminyaka ososayensi behlola le nkinga ebonakala ilula.
Ngo-1795, iFrance yakhipha umthetho owawuthi “igremu” “isisindo samanzi esiphelele kuyi-cube enomthamo olingana nengxenye yemitha yezinga lokushisa lapho iqhwa lincibilika (okungu-0°C).” Ngo-1799, ososayensi bathola ukuthi umthamo wamanzi uzinze kakhulu lapho ukuminyana kwamanzi kuphakeme kakhulu ku-4 ° C, ngakho incazelo yekhilogremu isishintshile yaba "isisindo se-cubic decimeter yamanzi ahlanzekile ku-4 ° C. ”. Lokhu kukhiqize ikhilogremu yoqobo eyiplatinum, ikhilogremu ichazwa njengelingana nesisindo sayo, esibizwa ngokuthi ikhilogremu yokugcinwa komlando.
Le kilogram yenqolobane isetshenziswe njengesilinganiso iminyaka engu-90. Ngo-1889, iNgqungquthela YokuQala Yamazwe Ngamazwe YeMetrology yagunyaza i-platinum-iridium alloy replica eseduze nekhilogremu egciniwe njengekhilogremu yangempela yamazwe ngamazwe. Isisindo "sekhilogremu" sichazwa nge-platinum-iridium alloy (90% platinum, 10% iridium) cylinder, ecishe ibe ngu-39 mm ubude nobubanzi, futhi okwamanje igcinwe egumbini elingaphansi emaphethelweni eParis.
Ikhilogremu yoqobo yamazwe ngamazwe
Kusukela ngeNkathi Yokukhanyiselwa, umphakathi ohlolayo uzibophezele ekusunguleni uhlelo lokuhlola indawo yonke. Nakuba kuyindlela enokwenzeka yokusebenzisa into ebonakalayo njengophawu lokulinganisa, ngenxa yokuthi into ebonakalayo ilinyazwa kalula izici ezenziwe umuntu noma zemvelo, ukuzinza kuzothinteka, futhi umphakathi wokulinganisa ubulokhu ufuna ukuyiyeka le ndlela ngokushesha. ngangokunokwenzeka.
Ngemva kokuba ikhilogremu yamukele incazelo yekhilogremu yoqobo yamazwe ngamazwe, kunombuzo izazi ze-metrologists ezikhathazeke kakhulu ngawo: izinze kangakanani le ncazelo? Ingabe izokhukhuleka ngokuhamba kwesikhathi?
Kufanele kushiwo ukuthi lo mbuzo waphakanyiswa ekuqaleni kwencazelo ye-mass unit kilogram. Isibonelo, lapho i-kilogram ichazwa ngo-1889, i-International Bureau of Weights and Measures yakhiqiza izisindo eziyi-7 ze-platinum-iridium alloy kilogram, enye yazo i-International I-kilogram yokuqala isetshenziselwa ukuchaza i-mass unit kilogram, nezinye izisindo ezingu-6. ezenziwe ngezinto ezifanayo kanye nenqubo efanayo isetshenziswa njengezilinganiso zesibili ukuhlola ukuthi ingabe kukhona ukukhukhuleka ngokuhamba kwesikhathi phakathi kokunye.
Ngesikhathi esifanayo, ngokuthuthukiswa kobuchwepheshe bokunemba okuphezulu, sidinga nezilinganiso ezizinzile nezinembile. Ngakho-ke, kwahlongozwa uhlelo lokuchaza kabusha iyunithi eyisisekelo yamazwe ngamazwe enezinto eziqinile eziqinile. Ukusebenzisa ama-constants ukuchaza amayunithi wokulinganisa 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, ukungaguquguquki kwekhwalithi yamanye amakhilogremu okuqala kanye nekhilogremu yangempela yamazwe ngamazwe kwashintsha cishe ngama-microgram angu-50. Lokhu kubonisa ukuthi kunenkinga ngokuzinza kwebhentshimakhi ebonakalayo yeyunithi yekhwalithi. Nakuba ushintsho lwama-micrograms angu-50 luzwakala luncane, lunomthelela omkhulu kwezinye izimboni ezisezingeni eliphezulu.
Uma ama-constants ayisisekelo asetshenziswayo esikhundleni sebhentshimakhi engokoqobo yekhilogremu, ukuzinza kweyunithi yesisindo ngeke kuthintwa isikhala nesikhathi. Ngakho-ke, ngo-2005, i-International Committee for Weights and Measures yabhala uhlaka lokusetshenziswa kwezinto eziyisisekelo ezingaguquki ukuze kuchazwe amanye amayunithi ayisisekelo e-International System of Units. Kunconywa ukuthi i-Planck njalo isetshenziselwe ukuchaza i-mass unit kilogram, futhi amalabhorethri anekhono kazwelonke ayakhuthazwa ukuba enze umsebenzi wocwaningo lwesayensi ohlobene.
Ngakho-ke, eNgqungqutheleni Yamazwe Ngamazwe Ye-Metrology ka-2018, ososayensi bavotele ukuyekisa ngokusemthethweni i-prototype kilogram, futhi bashintsha i-Planck constant (uphawu h) njengendlela entsha yokuchaza kabusha “kg”.
Isikhathi sokuthumela: Mar-05-2021