Ngo-1950, izazi ze-physics uGeorge Gamow noMarvin Stern zaphawula isenzakalo esithakazelisayo: UGamow, owayenehhovisi esitezi sokuqala sesakhiwo esinezitezi eziyisithupha, waphawula ukuthi ikheshi elifikayo lalihla izikhathi ezinhlanu kweziyisithupha, nakuba ayefuna. ukukhuphuka. UStern, owayesebenza esitezi sesihlanu, waphawula okuphambene.
Ikheshi ngokuvamile lalivela esitezi esiphezulu futhi liyehla lapho selifuna ukwehla. Esakhiweni esinezitezi eziningi, ilifti elandelayo efikayo ngokuvamile ibonakala ihamba ngendlela ehlukile kunaleyo oyilindele. Incazelo yalesi simo isesikhathini esihlukile amakheshi asichitha ezitezi ezihlukene.
Ezitezi eziphansi, ilifthi elandelayo yehla kaningi ngoba isikhathi sokuhamba siye phansi sifushane kunesikhathi esikhuphukayo. Ezitezi eziphakeme isimo siyahlehla: Lapha amathuba okuthi ikheshi elilandelayo likhuphuke liphezulu ngoba isikhathi sokuhamba ukwehla nokubuya side.
Uma usesitezi esiphezulu sesakhiwo, zonke izilifti zivela ngaphansi (akukho okungavela phezulu) bese zehla, kuyilapho esitezi sokugcina, ilifti eya esitezi esiphezulu iqala idlule bese kuthi ngemva kwesikhashana idlule yehle – ngakho-ke ngenkathi inani elifanayo lezilifti lidlula lenyuka njengoba lehla, izilifti ezehlayo ngokuvamile zilandela izilifti ezenyuka ngemva kwesikhashana, ngakho-ke ilifti yokuqala ebonwayo ivame ukwenyuka.
Ikheshi lokuqala elibhekwayo liyehla kuphela uma umuntu eqala ukubuka ngesikhathi esifushane ngemva kokuba ikheshi eliya phezulu lidlule, kuyilapho sonke isikhathi ikheshi elibonwa kuqala liyenyuka.
Ikheshi elilodwa lichitha isikhathi salo esiningi engxenyeni enkulu yesakhiwo ngakho-ke maningi amathuba okuthi lisuke kuleyo ndawo lapho kufika lowo osebenzisa ikheshi. Umuntu obukele owahlala eminyango yekheshi amahora noma izinsuku, ebuka ikheshi ngalinye lifika, kunokuba abuke nje ikheshi lokuqala , angaqaphela ukuthi kunenani elilinganayo lamakheshi aya ohlangothini ngalunye.
Sazi kanjani ukuthi kunezinombolo ezifanayo zamakheshi ohlangothini ngalunye? Lokhu kwenziwa ngokunakekela amakheshi . Uma, endaweni ethile, ngokuvamile kuba namakheshi amaningi akhuphukayo kunokwehla, inani lamakheshi liyokwehla kancane kancane ngaphansi kwalelo phuzu, okuyinto engenakwenzeka.