Ingakanani ubunzima bekhilogram? Izazinzulu bezihlola le ngxaki ebonakala ilula kangangeminyaka engamakhulu.
Ngo-1795, iFransi yapapasha umthetho owawuchaza "igram" njengo "bunzima obupheleleyo bamanzi kwityhubhu enomthamo olingana nekhulu lemitha kubushushu xa umkhenkce unyibilika (oko kukuthi, i-0°C)." Ngo-1799, izazinzulu zafumanisa ukuba umthamo wamanzi uzinzile kakhulu xa uxinano lwamanzi luphezulu kwi-4°C, ngoko ke inkcazo yekhilogram itshintshile yaba "bubunzima be-1 cubic decimeter yamanzi acocekileyo kwi-4°C". Oku kwavelisa ikhilogram yokuqala yeplatinum ecocekileyo, ikhilogram ichazwa njengelingana nobunzima bayo, ebizwa ngokuba yi-archives kilogram.
Le kilogram ye-archive isetyenzisiwe njengomlinganiselo kangangeminyaka engama-90. Ngo-1889, iNkomfa yokuQala yeHlabathi kwiMetrology yavuma ikopi ye-platinum-iridium alloy ekufutshane ne-archive kilogram njenge-pound yokuqala yehlabathi. Ubunzima be-"kilogram" buchazwa yi-platinum-iridium alloy (90% platinum, 10% iridium) cylinder, emalunga ne-39 mm ukuphakama nobubanzi, kwaye okwangoku igcinwe kwigumbi elingaphantsi komhlaba ngaphandle kweParis.
Ikhilogram yokuqala yamazwe ngamazwe
Ukususela kwiXesha lokuKhanyiselwa, uluntu oluhlola izinto luye lwazibophelela ekusekeni inkqubo yophando jikelele. Nangona yindlela enokwenzeka yokusebenzisa into ebonakalayo njengomlinganiselo wokulinganisa, kuba into ebonakalayo yonakaliswa lula zizinto ezenziwe ngumntu okanye zendalo, uzinzo luya kuchaphazeleka, kwaye uluntu oluhlola izinto belusoloko lufuna ukuyeka le ndlela ngokukhawuleza.
Emva kokuba ikhilogram yamkele inkcazo yekhilogram yokuqala yamazwe ngamazwe, kukho umbuzo oxhalatyelwe kakhulu ziingcali zemetro: ingaba le nkcazo izinzile kangakanani? Ngaba iya kuhamba ngokuhamba kwexesha?
Kunokuthiwa lo mbuzo uphakanyiswe ekuqaleni kwenkcazo yeyunithi yobunzima bekhilogram. Umzekelo, xa ikhilogram yachazwa ngo-1889, i-International Bureau of Weights and Measures yavelisa ubunzima bekhilogram yeplatinum-iridium alloy, enye yazo yi-International The original kilogram isetyenziselwa ukuchaza ubunzima beyunithi yekhilogram, kwaye ezinye ubunzima ezi-6 ezenziwe ngezinto ezifanayo kunye nenkqubo efanayo zisetyenziswa njengemilinganiselo yesibini yokujonga ukuba kukho ukushukuma ngokuhamba kwexesha phakathi komnye nomnye.
Kwangaxeshanye, ngophuhliso lwetekhnoloji echanekileyo, sikwafuna imilinganiselo ezinzileyo nechanekileyo ngakumbi. Ke ngoko, kwacetywa icebo lokuchaza ngokutsha iyunithi esisiseko yamazwe ngamazwe ngee-physical constants. Ukusebenzisa ii-constants ukuchaza iiyunithi zokulinganisa kuthetha ukuba ezi nkcazo ziya kuhlangabezana neemfuno zesizukulwana esilandelayo sezinto ezifunyenweyo zesayensi.
Ngokwedatha esemthethweni ye-International Bureau of Weights and Measures, kwiminyaka eli-100 ukusuka ngo-1889 ukuya ku-2014, ukuhambelana komgangatho kwezinye iikhilogram zokuqala kunye nekhilogram yokuqala yehlabathi kwatshintsha malunga nee-microgram ezingama-50. Oku kubonisa ukuba kukho ingxaki ngokuzinza komgangatho womgangatho weyunithi yomgangatho. Nangona utshintsho lwee-microgram ezingama-50 luvakala luncinci, lunempembelelo enkulu kwamanye amashishini aphezulu.
Ukuba ii-constants ezisisiseko zomzimba zisetyenziselwa ukuthatha indawo ye-kilogram physical benchmark, ukuzinza kweyunithi yobunzima akuyi kuchaphazeleka yindawo nexesha. Ke ngoko, ngo-2005, iKomiti yeHlabathi yeZisindo kunye neMilinganiselo yaqulunqa isakhelo sokusetyenziswa kwee-constants ezisisiseko zomzimba ukuchaza ezinye iiyunithi ezisisiseko zeNkqubo yeeYunithi zeHlabathi. Kucetyiswa ukuba i-constant yePlanck isetyenziswe ukuchaza iyunithi yobunzima ikhilogram, kwaye iilabhoratri ezifanelekileyo zenqanaba lesizwe ziyakhuthazwa ukuba zenze umsebenzi wophando lwesayensi onxulumene noko.
Ngenxa yoko, kwiNgqungquthela yeHlabathi yeMetrology ka-2018, izazinzulu zivotele ukuba i-prototype kilogram yelizwe jikelele irhoxiswe ngokusemthethweni, zaza zatshintsha i-Planck constant (uphawu h) njengomgangatho omtsha wokuchaza ngokutsha i-"kg".
Ixesha lokuthumela: Matshi-05-2021