What is at the center of the universe? It's an essential question that humans have been wondering about for centuries. But the journey toward an answer has been a strange one. If you wanted to know the answer to this question in third century B.C.E. Greece, you might look up at the night sky and trust what you see. That's what Aristotle, THE guy to ask back then, did. He thought that since we're on Earth, looking up, it must be the center, right? For him, the sphere of the world was made up of four elements: Earth, water, air, and fire. These elements shifted around a nested set of solid crystalline spheres. Each of the wandering stars, the planets, had their own crystal sphere. The rest of the universe and all of its stars were on the last crystal sphere. If you watch the sky change over time, you could see that this idea worked fine at explaining the motion you saw. For centuries, this was central to how Europe and the Islamic world saw the universe. But in 1543, a guy named Copernicus proposed a different model. He believed that the sun was at the center of the universe. This radically new idea was hard for a lot of people to accept. After all, Aristotle's ideas made sense with what they could see, and they were pretty flattering to humans. But a series of subsequent discoveries made the sun-centric model hard to ignore. First, Johannes Kepler pointed out that orbits aren't perfect circles or spheres. Then, Galileo's telescope caught Jupiter's moons orbiting around Jupiter, totally ignoring Earth. And then, Newton proposed the theory of universal gravitation, demonstrating that all objects are pulling on each other. Eventually, we had to let go of the idea that we were at the center of the universe. Shortly after Copernicus, in the 1580s, an Italian friar, Giordano Bruno, suggested the stars were suns that likely had their own planets and that the universe was infinite. This idea didn't go over well. Bruno was burned at the stake for his radical suggestion. Centuries later, the philosopher Rene Descartes proposed that the universe was a series of whirlpools, which he called vortices, and that each star was at the center of a whirlpool. In time, we realized there were far more stars than Aristotle ever dreamed. As astronomers like William Herschel got more and more advanced telescopes, it became clear that our sun is actually one of many stars inside the Milky Way. And those smudges we see in the night sky? They're other galaxies, just as vast as our Milky Way home. Maybe we're farther from the center than we ever realized. In the 1920s, astronomers studying the nebuli wanted to figure out how they were moving. Based on the Doppler Effect, they expected to see blue shift for objects moving toward us, and red shift for ones moving away. But all they saw was a red shift. Everything was moving away from us, fast. This observation is one of the pieces of evidence for what we now call the Big Bang Theory. According to this theory, all matter in the universe was once a singular, infinitely dense particle. In a sense, our piece of the universe was once at the center. But this theory eliminates the whole idea of a center since there can't be a center to an infinite universe. The Big Bang wasn't just an explosion in space; it was an explosion of space. What each new discovery proves is that while our observations are limited, our ability to speculate and dream of what's out there isn't. What we think we know today can change tomorrow. As with many of the thinkers we just met, sometimes our wildest guesses lead to wonderful and humbling answers and propel us toward even more perplexing questions.
Šta je u središtu svemira? To je suštinsko pitanje koje su ljudi postavljali vekovima, ali je put prema odgovoru bio čudan. Ako ste želeli da znate odgovor na ovo pitanje u trećem veku p. n. e. u Grčkoj, možda biste pogledali u noćno nebo i verovali onome što vidite. To je ono što je Aristotel, glavni momak tog vremena, uradio. Mislio je, pošto smo na Zemlji, gledajući naviše, ona mora biti centar, zar ne? Za njega, sfera sveta bila je sačinjena od četiri elementa: zemlje, vode, vazduha i vatre. Ovi elementi smenjivali su se u ugnežđenom skupu čvrstih kristalnih sfera. Svaka lutajuća zvezda, planeta, imala je sopstvenu kristalnu sferu. Ostatak svemira i sve njegove zvezde bili su na poslednjoj kristalnoj sferi. Ako posmatrate nebo kako se vremenom menja, možete videti da je ova ideja dobro funkcionisala kod objašnjavanja kretanja koja ste videli. Vekovima je ovo bilo središte toga kako su Evropa i muslimanski svet videli svemir. Međutim, 1543. godine, momak pod imenom Kopernik predložio je drugačiji model. Verovao je da je Sunce u centru svemira. Ljudima je bilo teško da prihvate ovu radikalno novu ideju. Na kraju krajeva, Aristotelova ideja bila je smislena prema onome što su mogli da vide, a i prilično su laskale ljudima. Međutim, niz pratećih otkrića učinio je da je model sa Suncem kao središtem bilo teško ignorisati. Prvo je Johanes Kepler istaknuo da orbite nisu savršeno kružne sfere. Zatim je Galileov teleskop uhvatio Jupiterove Mesece kako kruže oko Jupitera, potpuno ignorišući Zemlju, a onda je Njutn predložio teoriju univerzalne gravitacije, demonstrirajući da se svi predmeti međusobno privlače. Na kraju, morali smo da zaboravimo ideju da smo centar svemira. Ubrzo posle Kopernika, oko 1580. godine, italijanski fratr, Đordano Bruno, ukazao je da su zvezde Sunca koja verovatno imaju sopstvene planete, a da je svemir beskonačan. Ova ideja nije dobro prošla. Bruno je spaljen na lomači zbog radikalnog predloga. Vekovima posle toga, filozof Rene Dekart izneo je da je svemir sačinjen od nizova virova, koje je zvao vrtlozi, a svaka je zvezda središte vrtloga. Vremenom smo shvatili da postoji mnogo više zvezda nego što je Aristotel mogao da sanja. Kako su astronomi kao što je Vilijem Herčel dobijali sve razvijenije teleskope, postalo je jasno da je naše Sunce zapravo jedno od mnogih zvezda unutar Mlečnog puta. A mrlje koje vidimo na noćnom nebu? To su druge galaksije, ogromne kao i naš dom, Mlečni put. Možda smo još udaljeniji od centra nego što smo to ikada shvatali. Godine 1920, astronomi koji su proučavali svemirske magline želeli su da shvate kako se kreću. Na osnovu Doplerovog efekta, očekivali su da vide plavi pomak za predmete koji se kreću prema nama, a crveni pomak za one koji se udaljavaju, ali jedino što su videli je crveni pomak. Sve se udaljavalo od nas, i to brzo. Ovo zapažanje je jedan od dokaza za ono što danas prepoznajemo kao teoriju velikog praska. Prema toj teoriji, sva materija u svemiru nekada je bila jedinstvena, beskrajno gusta čestica. Na neki način, naš deo svemira bio je nekada u središtu. Međutim, ova teorija isključuje celokupnu ideju o središtu pošto ne može postojati centar beskrajnog svemira. Veliki prasak nije bio samo eksplozija u svemiru; bila je to eksplozija svemira. Ono što svako novo otkriće potvrđuje je da, dok su naša zapažanja ograničena, naša sposobnost da razmišljamo i sanjamo o onome što je tamo negde - nije. Ono što danas mislimo da znamo može se promeniti sutra. Kao i kod mnogih mislilaca koje smo upravo sreli, ponekad naše najluđe pretpostavke vode ka divnim i skromnim odgovorima i pokreću nas da idemo ka još zagonetnijim pitanjima.