Ungakwazi yini ukukhiqiza isifinyezo semigqa emibili salombhalo?
Context:Ku-physics, amandla adonsela phansi (ngesiLatini gravitas 'isisindo') kuwukuhlangana okuyisisekelo okubangela ukuncintisana phakathi kwazo zonke izinto ezinobunzima noma amandla. Amandla adonsela phansi, ngokusobala, abuthakathaka kunawo wonke emandleni amane ayisisekelo, cishe abuthakathaka ngokuphindwe izikhathi ezingu-1038 kunamandla adonsela phansi aqinile, aphindwe izikhathi ezingu-1036 kunamandla adonsela phansi kagesi futhi aphindwe izikhathi ezingu-1029 kunamandla adonsela phansi abuthakathaka. Ngenxa yalokho, ayinalo ithonya elibalulekile ezingeni lezinhlayiya ezingaphansi kwe-athomu. Nokho, amandla adonsela phansi ayisici esibaluleke kunazo zonke phakathi kwezinto ezisesilinganisweni esikhulu, futhi anquma ukunyakaza kwamaplanethi, izinkanyezi, imithala ngisho nokukhanya.  Emhlabeni, amandla adonsela phansi anikeza isisindo ezintweni ezibonakalayo, futhi amandla adonsela phansi eNyangeni anesibopho samagagasi angaphansi kwenyanga olwandle (amagagasi ahambelana ne-antipodal abangelwa ukungabi namandla komhlaba nenyanga ezungeza enye nenye). Amandla adonsela phansi nawo anemisebenzi eminingi ebalulekile yezinto eziphilayo, esiza ekuqondiseni ukukhula kwezitshalo ngenqubo ye-gravitropism futhi athonya ukujikeleza koketshezi ezidalweni ezinamaseli amaningi. Ukucwaninga ngemiphumela yokungabi nasisindo kuye kwabonisa ukuthi amandla adonsela phansi angase abe nendima ekusebenzeni kwesimiso somzimba sokuzivikela ezifweni nasekuhlukaneni kwamangqamuzana emzimbeni womuntu.  Amandla adonsela phansi phakathi kwento eyigesi yasekuqaleni endaweni yonke ayivumela ukuba ihlangane futhi yakhe izinkanyezi ekugcineni ezahlangana zaba imithala, ngakho amandla adonsela phansi ayimbangela yezakhiwo eziningi ezinkulu endaweni yonke. Amandla adonsela phansi anobubanzi obungenamkhawulo, nakuba imiphumela yawo iba buthakathaka njengoba izinto ziba kude.  Amandla adonsela phansi achazwa ngokunembile kakhulu yi-General Theory of Relativity (ephakanyiswe ngu-Albert Einstein ngo-1915), echaza amandla adonsela phansi hhayi njengamandla, kodwa njengokugobeka kwesikhala-isikhathi, okubangelwa ukusatshalaliswa okungafani kwesisindo, futhi okubangela ukuthi izixuku zihambe ngemigqa ye-geodesic. Isibonelo esibi kakhulu salokhu kuguquguquka kwesikhala-isikhathi umgodi omnyama, lapho kungekho lutho - ngisho nokukhanya - okungaphunyuka khona uma sekudlulile emkhathizwe wesigameko somgodi omnyama. Nokho, ekusetshenzisweni okuningi, amandla adonsela phansi asondele kahle emthethweni kaNewton wokudonsela phansi kwendawo yonke, ochaza amandla adonsela phansi njengamandla abangela noma yiziphi izidumbu ezimbili ukuthi zidonswe komunye nomunye, ngobukhulu obulingana nomkhiqizo wemisa yazo futhi ngokulinganayo ngokulingana nesikwele sebanga eliphakathi kwazo.
Emfundisweni ye-physics evamile (Newton), amandla adonsela phansi adonsela izinto komunye nomunye ngokususelwa emananini azo kanye nesikwele sebanga elizihlukanisayo. Emfundisweni yokuhlobana (ka-Einstein), kuwukugoba kwesikhala-sikhathi okubangelwa yizinto ngokwazo.