Lub cev dub kiag li hu ua qhov no vim tias nws nqus tag nrho cov hluav taws xob poob rau ntawm nws (lossis theej, rau hauv nws) ob qho tib si hauv qhov pom thiab dhau mus. Tab sis yog hais tias lub cev tsis kub, lub zog yog re-radiated rov qab. Qhov hluav taws xob no tawm los ntawm lub cev dub tag nrho yog qhov txaus siab tshwj xeeb. Thawj qhov kev sim los kawm txog nws cov khoom tau ua txawm tias ua ntej lub ntsej muag ntawm tus qauv nws tus kheej.
Nyob rau xyoo 19th, John Leslie tau sim ntau yam tshuaj. Raws li nws tau muab tawm, cov hmoov av dub tsis tsuas yog absorbs tag nrho cov teeb pom kev poob rau ntawm nws. Nws radiated nyob rau hauv infrared ntau npaum li cas muaj zog tshaj lwm yam, sib dua, tshuaj. Nws yog thermal tawg, uas txawv los ntawm tag nrho cov lwm yam nyob rau hauv ntau yam khoom. Cov hluav taws xob ntawm lub cev dub tag nrho yog qhov sib npaug, homogeneous, tshwm sim tsis muaj zog hloov pauv thiab nyob ntawm qhov kub ntawm lub cev xwb.
Thaum qhov kub ntawm qhov khoom siab txaus, cov hluav taws xob thermal yuav pom, thiab tom qab ntawd txhua lub cev, suav nrog cov xim dub kiag li, tau txais xim.
Qhov khoom tshwj xeeb uas tawm tsuas yog qee yam ntawm lub zog, tsis tuaj yeem pab tab sis nyiam mloog. Txij li thaum peb tab tom tham txog cov hluav taws xob thermal, thawj cov qauv thiab cov kev xav txog qhov spectrum yuav tsum zoo li cas tau thov nyob rau hauv lub moj khaum ntawm thermodynamics. Classical thermodynamics muaj peev xwm txiav txim siab ntawm qhov wavelength qhov siab tshaj plaws hluav taws xob yuav tsum nyob ntawm qhov kub thiab txias, nyob rau hauv qhov kev taw qhia thiab ntau npaum li cas nws yuav hloov thaum rhuab thiab txias. Txawm li cas los xij, nws tsis tuaj yeem kwv yees tias qhov kev faib tawm ntawm lub zog hauv lub cev dub spectrum ntawm tag nrho cov wavelengths thiab, tshwj xeeb tshaj yog, nyob rau hauv ultraviolet ntau yam.
Raws li cov thermodynamics classical, lub zog tuaj yeem tso tawm hauv txhua qhov, suav nrog cov me me. Tab sis txhawm rau kom lub cev dub kiag li tawg ntawm lub wavelengths luv, lub zog ntawm qee qhov ntawm nws cov khoom yuav tsum loj heev, thiab hauv cheeb tsam ntawm ultrashort nthwv dej nws yuav mus rau infinity. Nyob rau hauv kev muaj tiag, qhov no yog tsis yooj yim sua, infinity tshwm sim nyob rau hauv qhov sib npaug thiab hu ua lub ultraviolet kev puas tsuaj. Tsuas yog Planck txoj kev xav tias lub zog tuaj yeem raug hluav taws xob hauv qhov sib cais - quanta - pab daws qhov nyuaj. Niaj hnub no qhov sib npaug ntawm thermodynamics yog qhov tshwj xeeb ntawm qhov sib npaug ntawm quantum physics.
Thaum xub thawj, lub cev dub tag nrho tau sawv cev raws li kab noj hniav nrog qhov qhib nqaim. Cov hluav taws xob tawm sab nraud nkag mus rau hauv cov kab noj hniav zoo li no thiab yog nqus los ntawm cov phab ntsa. Nyob rau spectrum ntawm hluav taws xob, uasyuav tsum muaj lub cev dub kiag li, nyob rau hauv cov ntaub ntawv no, lub spectrum ntawm hluav taws xob los ntawm kev nkag mus rau lub qhov tsua, qhib lub qhov dej, lub qhov rais mus rau lub tsaus chav tsev nyob rau hauv ib hnub tshav ntuj, thiab lwm yam. Tab sis feem ntau ntawm tag nrho cov, lub spectrum ntawm cosmic keeb kwm yav dhau hluav taws xob ntawm lub ntiaj teb no thiab cov hnub qub, nrog rau lub hnub, coincide nrog nws.
Nws muaj kev nyab xeeb hais tias ntau qhov sib txawv nrog lub zog sib txawv hauv ib yam khoom, qhov muaj zog ntawm nws cov hluav taws xob yuav zoo li lub cev dub. Lub zog faib nkhaus nyob rau hauv lub spectrum ntawm lub cev dub qhia txog cov qauv kev txheeb cais hauv cov kab ke ntawm cov khoom no, nrog rau kev kho tsuas yog tias lub zog hloov pauv thaum sib cuam tshuam yog sib cais.
