We know about our universe’s past: the Big Bang theory predicts that all matter, time, and space began in an incredibly tiny, compact state about 14 billion years ago. And we know about the present: scientists’ observations of the movement of galaxies tell us that the universe is expanding at an accelerated rate. But what about the future? Do we know how our universe is going to end?
Tunajua ya kale ya ulimwengu wetu: nadharia ya Mlipuko Mkubwa inatabiri kuwa mata, muda na anga zote vilianza kwa hali ya udogo sana, takribani miaka bilioni 14 iliyopita. Nasi tunajua kuhusu sasa: mitazamo ya watafiti ya mienendo ya galaksi inatuambia kwamba ulimwengu unapanuka kwa kasi sana. Je vipi kuhusu mbeleni? Tunajua namna gani ulimwengu wetu utafikia kikomo?
Cosmologists have three possible answers for this question, called the Big Freeze, the Big Rip and the Big Crunch.
Wanakosmolojia wana nadharia tatu za swali hili, zinazoitwa Mgando Mkubwa, Mraruo Mkubwa na Uchakacho Mkubwa.
To understand these three scenarios, imagine two objects representing galaxies. A short, tight rubber band is holding them together— that’s the attractive force of gravity. Meanwhile, two hooks are pulling them apart— that’s the repulsive force expanding the universe. Copy this system over and over again, and you have something approximating the real universe. The outcome of the battle between these two opposing forces determines how the end of the universe will play out.
Kuzielewa hizi nadharia tatu, waza vitu viwili vya kuwakilisha galaksi. Kamba ya mpira fupi, iliyokaza inazishikilia pamoja--- hiyo ni mvuto wa nguvu ya uvutano. Wakati huo huo, koleo mbili zinaziachanisha--- hiyo ni nguvu ya muasi inayofanya ulimwengu usambae. Nakili huu mfumo tena na tena, Na una kitu kinachokaribia ulimwengu wa ukweli. Matokeo ya mashindano ya hizi nguvu mbili zinazokinzana inaamua jinsi mwisho wa ulimwengu utakuwaje.
The Big Freeze scenario is what happens if the force pulling the objects apart is just strong enough to stretch the rubber band until it loses its elasticity. The expansion wouldn’t be able to accelerate anymore, but the universe would keep getting bigger. Clusters of galaxies would separate. The objects within the galaxies– suns, planets, and solar systems would move away from each other, until galaxies dissolved into lonely objects floating separately in the vast space. The light they emit would be redshifted to long wavelengths with very low, faint energies, and the gas emanating from them would be too thin to create new stars. The universe would become darker and colder, approaching a frozen state also known as the Big Chill, or the Heat Death of the Universe.
Matukio ya Mgando Mkubwa ndiyo yanayotokea kama nguvu inayofanya vitu viachane ina nguvu ya kutosha ya kuisogeza kamba ya mpira hadi ipoteze uvutikaji. Kusogea hakutoweza kuongezeka tena, lakini ulimwengu utazidi kuwa mkubwa. Makundi ya galaksi yanaweza kutengana. Vitu vilivyomo kwenye galaksi-- jua, sayari, na mifumo wa jua vingeweza kutengana, mpaka galaksi ziyeyuke kuwa vitu vya kipekee vikielea kwa kujitegemea kwenye anga kubwa. Mwanga unaotoka ungeweza kuhamishwa kwenye mawimbi marefu yenye nguvu kidogo na hafifu, na gesi inayotoka kwao ingekua nyembamba sana kutengeneza nyota mpya. Ulimwengu ungekuwa wa giza na wa baridi zaidi, ukikaribia hali ya kuganda unaojulikanana kama Ubaridi Mkubwa, au kifo cha joto cha Ulimwengu.
But what if the repulsive force is so strong that it stretches the rubber band past its elastic limit, and actually tears it? If the expansion of the universe continues to accelerate, it will eventually overcome not only the gravitational force – tearing apart galaxies and solar systems– but also the electromagnetic, weak, and strong nuclear forces which hold atoms and nuclei together. As a result, the matter that makes up stars breaks into tiny pieces. Even atoms and subatomic particles will be destroyed. That’s the Big Rip.
Lakini inakuwaje kama nguvu muasi ni kubwa sana kufanya kamba ya mpira ipanuke kupita kipimo chake, na iichane kabisa? Kama kutanuka kwa ulimwengu kunazidi kuongezeka, itaweza kuzidi sio tu nguvu ya uvutano -- ikichana galaksi na mifumo ya jua-- lakini pia na nguvu hafifu ya sumaku umeme,na nguvu za nguvu za nuklia ambayo inashikilia atomu na nuklia pamoja. Matokeo yake, mata inayotengeneza nyota inavunjika katika vipande vidogo. Hata atomu na vipande vidogo vya atomu vitaharibika. Hiyo ni Mraruo Mkubwa.
What about the third scenario, where the rubber band wins out? That corresponds to a possible future in which the force of gravity brings the universe’s expansion to a halt— and then reverses it. Galaxies would start rushing towards each other, and as they clumped together their gravitational pull would get even stronger. Stars too would hurtle together and collide. Temperatures would rise as space would get tighter and tighter. The size of the universe would plummet until everything compressed into such a small space that even atoms and subatomic particles would have to crunch together. The result would be an incredibly dense, hot, compact universe — a lot like the state that preceded the Big Bang. This is the Big Crunch.
Vipi kuhusu tukio la tatu, ambapo kamba ya mpira inashinda? Ambayo ina shabihiana na uwezekano wa mbeleni ambapo nguvu ya uvutano inaletea kusambaa kwa ulimwengu kusimama--- Halafu inaigeuza. Galaksi zitaanza kukimbizana kukaribiana, na zikijikusanya pamoja nguvu zao za uvutano zingekua na nguvu zaidi. Nyota pia zingekusanyika pamoja na kugongana. Joto lingepanda kadri anga inavyozidi kujibana zaidi. Ukubwa waa ulimwengu ungekua timazi hadi kila kitu kilichojikusanyika kwenye nafasi ndogo mpaka hadi chembe za atomu na atomu ndogo vitajikusanyika pamoja. Matokeo yatakuwa ni ulimwengu mzito, wenye joto na ulio jifunga --- kama ile hali iliyoitangulia Big Bang. Hii ndiyo Uchakacho Mkubwa.
Could this tiny point of matter explode in another Big Bang? Could the universe expand and contract over and over again, repeating its entire history? The theory describing such a universe is known as the Big Bounce. In fact, there’s no way to tell how many bounces could’ve already happened— or how many might happen in the future. Each bounce would wipe away any record of the universe’s previous history.
Je hii sehemu ndogo ya mata inaweza kulipuka kuwa Mlipuko Mkubwa mwingine? Ulimwengu unaweza kuongezeka na kujifunga tena na tena, ikirudia historia yake yote? Nadharia inayoeleza ulimwengu huo unajulikana kama Mruko Mkubwa. Pia hamna namna ya kujua miruko mingapi imeshatokea tayari--- au mingapi itatokea huko mbeleni. Kila mruko itafuta mbali kumbukumbu yeyote ya historia ya ulimwengu ya nyuma.
Which one of those scenarios will be the real one? The answer depends on the exact shape of the universe, the amount of dark energy it holds, and changes in its expansion rate. As of now, our observations suggest that we’re heading for a Big Freeze. But the good news is that we’ve probably got about 10 to the 100th power years before the chill sets in — so don’t start stocking up on mittens just yet.
Matukio yapi kati ya haya yatakuwa sahihi? Jibu linategemea na umbo halisi la ulimwengu, kiasi cha nguvu ya gizai iliyobeba, na mabadiliko ya kusambaa kwake. Na kwa sasa, mitazamo yetu inapendekeza kua tunaelekea kwenye Mgando Mkubwa. Japo habari njema ni kwamba tuna karibia miaka 10 mpaka nguvu ya 100 kabla ya ubaridi kuingia --- kwahiyo usianze kununua kinga za mkononi bado.