The universe is really big. We live in a galaxy, the Milky Way Galaxy. There are about a hundred billion stars in the Milky Way Galaxy. And if you take a camera and you point it at a random part of the sky, and you just keep the shutter open, as long as your camera is attached to the Hubble Space Telescope, it will see something like this. Every one of these little blobs is a galaxy roughly the size of our Milky Way -- a hundred billion stars in each of those blobs. There are approximately a hundred billion galaxies in the observable universe. 100 billion is the only number you need to know. The age of the universe, between now and the Big Bang, is a hundred billion in dog years. (Laughter) Which tells you something about our place in the universe.
Svemir je zaista ogroman. Živimo u galaksiji Mlečni put, u kojoj ima oko sto milijardi zvezda. I ako uzmete kameru i uperite je bilo gde ka nebu, i skinete poklopac, ako vam je kamera priključena na svemirski telskop Habl, videće nešto ovako. Svaka od tih malih mrlja je galaksija veličine slične našem Mlečnom putu - sto milijardi zvezda u svakoj od tih mrlja. Ima oko sto milijardi galaksija u vidljivom svemiru. Sto milijardi je jedini broj koji treba da znate. Starost svemira, između Velikog praska i sadašnosti, je sto milijardi u psećim godinama. (Smeh) Što vam govori nešto o našem mestu u svemiru.
One thing you can do with a picture like this is simply admire it. It's extremely beautiful. I've often wondered, what is the evolutionary pressure that made our ancestors in the Veldt adapt and evolve to really enjoy pictures of galaxies when they didn't have any. But we would also like to understand it. As a cosmologist, I want to ask, why is the universe like this? One big clue we have is that the universe is changing with time. If you looked at one of these galaxies and measured its velocity, it would be moving away from you. And if you look at a galaxy even farther away, it would be moving away faster. So we say the universe is expanding.
Jedino što možete sa ovom slikom jeste da joj se divite. Neverovatno je lepa. Često sam se pitao kakav je to pritisak evolucije terao naše pretke u Africi da se prilagođavaju i evoluiraju da bi uživali u slikama galaksije kada ih nisu imali. Ali i mi bismo voleli da razumemo to. Kao kosmolog, želim da se pitam, zašto je svemir ovakav? Veliki trag koji imamo jeste da se svemir vremenom menja. Ako pogledate jednu od ovih galaksija i izmerite njenu brzinu, ona će se udaljavati od vas. A ako pogledate još udaljeniju galaksiju, ona će se udaljavati još brže. Zato kažemo da se svemir širi.
What that means, of course, is that, in the past, things were closer together. In the past, the universe was more dense, and it was also hotter. If you squeeze things together, the temperature goes up. That kind of makes sense to us. The thing that doesn't make sense to us as much is that the universe, at early times, near the Big Bang, was also very, very smooth. You might think that that's not a surprise. The air in this room is very smooth. You might say, "Well, maybe things just smoothed themselves out." But the conditions near the Big Bang are very, very different than the conditions of the air in this room. In particular, things were a lot denser. The gravitational pull of things was a lot stronger near the Big Bang.
To, naravno, znači da su u prošlosti stvari bile skupljenije. U prošlosti, svemir je bio gušći i takođe, topliji. Ako sabijete stvari zajedno, temperatura raste. To nam je nekako logično. Ono što nije tako logično jeste da je svemir, u rano doba, blizu Velikog praska takođe bio vrlo vrlo gladak. To vas možda ne iznenađuje. Vazduh u ovoj sobi je vrlo gladak. Mislite: "Pa, možda su se stvari same izgladile". Ali stanja blizu Velikog praska su vrlo različita od stanja vazduha u ovoj sobi. Tačnije, stvari su bile mnogo gušće. Gravitacione sile su bile mnogo jače blizu Velikog praska.
What you have to think about is we have a universe with a hundred billion galaxies, a hundred billion stars each. At early times, those hundred billion galaxies were squeezed into a region about this big -- literally -- at early times. And you have to imagine doing that squeezing without any imperfections, without any little spots where there were a few more atoms than somewhere else. Because if there had been, they would have collapsed under the gravitational pull into a huge black hole. Keeping the universe very, very smooth at early times is not easy; it's a delicate arrangement. It's a clue that the early universe is not chosen randomly. There is something that made it that way. We would like to know what.
Morate da shvatite da svemir ima sto milijardi galaksija, svaka sa po sto milijardi zvezda. U rano doba, tih sto milijardi galaksija je bilo sabijeno u prostor ove veličine - bukvalno, u rano doba. I zamislite to sabijanje savršeno izvedeno, bez nekih malih tačaka gde ima par atoma više nego negde drugde. Da je bilo tako, urušili bi se pod gravitacionim silama u ogromnu crnu rupu. Održati svemir vrlo glatkim u rano doba je bio vrlo delikatan zadatak. To je trag da rani svemir nje bio nasumično odabran. Nešto ga je učinilo takvim. Želeli bismo da znamo šta.
So part of our understanding of this was given to us by Ludwig Boltzmann, an Austrian physicist in the 19th century. And Boltzmann's contribution was that he helped us understand entropy. You've heard of entropy. It's the randomness, the disorder, the chaoticness of some systems. Boltzmann gave us a formula -- engraved on his tombstone now -- that really quantifies what entropy is. And it's basically just saying that entropy is the number of ways we can rearrange the constituents of a system so that you don't notice, so that macroscopically it looks the same. If you have the air in this room, you don't notice each individual atom. A low entropy configuration is one in which there's only a few arrangements that look that way. A high entropy arrangement is one that there are many arrangements that look that way. This is a crucially important insight because it helps us explain the second law of thermodynamics -- the law that says that entropy increases in the universe, or in some isolated bit of the universe.
Ludvig Boltcman, austrijski fizičar iz 19. veka, nam je dao delimično rešenje. Boltcmanov doprinos je u tome što nam je pomogao da razumemo entropiju. Čuli ste za entropiju. To je nasumičnost, nered, haotičnost nekih sistema. Boltzman nam je dao formulu, koja je ugravirana na njegovom nadgrobnom spomeniku, koja zaista objašnjava entropiju. I u osnovi nam kaže da je entropija broj načina na koji možemo da preuredimo delove sistema, tako da ne primetite, tako da on makroskopski izgleda isto. Na primer, vazduh u ovoj sobi, ne primetite njegov svaki pojedinačni atom. Sklop sa niskom entropijom je onaj gde postoji samo par takvih uređenja. Sklop sa visokom entropijom je onaj gde postoji veliki broj takvih uređenja. To je uvid od ključne važnosti, jer nam pomaže da objasnimo drugi zakon termodinamike - zakon po kome se entropija povećava u svemiru, ili u izolovanom delu svemira.
The reason why entropy increases is simply because there are many more ways to be high entropy than to be low entropy. That's a wonderful insight, but it leaves something out. This insight that entropy increases, by the way, is what's behind what we call the arrow of time, the difference between the past and the future. Every difference that there is between the past and the future is because entropy is increasing -- the fact that you can remember the past, but not the future. The fact that you are born, and then you live, and then you die, always in that order, that's because entropy is increasing. Boltzmann explained that if you start with low entropy, it's very natural for it to increase because there's more ways to be high entropy. What he didn't explain was why the entropy was ever low in the first place.
Entropija se povećava jer jednostavno ima mnogo više načina da se postigne visoka nego niska entropija. To je divan uvid, ali nešto izostavlja. Usput, uvid da se entropija povećava objašnjava ono što nazivamo strelom vremena, razliku između prošlosti i budućnosti. Svaka razlika između prošlosti i budućnosti postoji jer se entropija povećava - to što se sećate prošlosti, ali ne i budućnosti. To što se rađamo, živimo i umiremo, uvek tim redom, je zato što se entropija povećava. Boltcman je objasnio da ako se krene od niske entropije, prirodno je da se ona povećava. zato što postoji više načina da se postigne visoka entropija. Ali nije objasnio zašto je entropija niska na početku.
The fact that the entropy of the universe was low was a reflection of the fact that the early universe was very, very smooth. We'd like to understand that. That's our job as cosmologists. Unfortunately, it's actually not a problem that we've been giving enough attention to. It's not one of the first things people would say, if you asked a modern cosmologist, "What are the problems we're trying to address?" One of the people who did understand that this was a problem was Richard Feynman. 50 years ago, he gave a series of a bunch of different lectures. He gave the popular lectures that became "The Character of Physical Law." He gave lectures to Caltech undergrads that became "The Feynman Lectures on Physics." He gave lectures to Caltech graduate students that became "The Feynman Lectures on Gravitation." In every one of these books, every one of these sets of lectures, he emphasized this puzzle: Why did the early universe have such a small entropy?
To što je entropija svemira bila niska odražava činjenicu da je rani svemir bio vrlo, vrlo gladak. Hteli bismo to da razumemo. To je posao nas kosmologa. Nažalost, to je problem kome smo posvetili malo pažnje. On nije jedna od prvih stvari koje biste čuli ako biste pitali savremenog kosmologa, "Koje probleme pokušavamo da rešimo?" Jedan od ljudi koji je shvatio da je ovo problem je bio Ričard Fejnman. Pre 50 godina, održao je niz različitih predavanja. Držao je popularna predavanja koja su postala "Lik fizičkog zakona". Držao je predavanja studentima na Kalteku koja su postala "Fejnmanova predavanja o fizici." Držao je predavanja diplomcima na Kalteku koja su postala "Fejnmanova predavanja o gravitaciji" U svim tim knjigama, tim nizovima predavanja, naglašavao je ovu zagonetku: zašto je rani svemir imao tako nisku entropiju?
So he says -- I'm not going to do the accent -- he says, "For some reason, the universe, at one time, had a very low entropy for its energy content, and since then the entropy has increased. The arrow of time cannot be completely understood until the mystery of the beginnings of the history of the universe are reduced still further from speculation to understanding." So that's our job. We want to know -- this is 50 years ago, "Surely," you're thinking, "we've figured it out by now." It's not true that we've figured it out by now.
I rekao je, neću imitirati akcenat: "Iz nekog razloga, svemir je u jednom trenutku, imao vrlo nisku entropiju u odnosu na njegovu energiju, i od tada entropija se uvećala. Strela vremena se ne može u potpunosti razumeti dok se misterija o početku istorijie svemira ne svede sa nagađanja na razumevanje". To je naš posao. To je bilo pre 50 godina. Vi mislite: "Sigurno smo do sada shvatili." Nije istina da smo do sada shvatili.
The reason the problem has gotten worse, rather than better, is because in 1998 we learned something crucial about the universe that we didn't know before. We learned that it's accelerating. The universe is not only expanding. If you look at the galaxy, it's moving away. If you come back a billion years later and look at it again, it will be moving away faster. Individual galaxies are speeding away from us faster and faster so we say the universe is accelerating. Unlike the low entropy of the early universe, even though we don't know the answer for this, we at least have a good theory that can explain it, if that theory is right, and that's the theory of dark energy. It's just the idea that empty space itself has energy.
Problem je postao i teži, umesto da postane lakši, jer smo 1998. godine saznali nešto ključno o svemiru što nismo znali ranije. Saznali smo da on ubrzava. Širenje je samo jedna karakteristika svemira. Pogledajte galaksiju, ona se udaljava. Pogledajte je opet za milijardu godina, i udaljavaće se još brže. Pojedine galaksije ubrzavaju od nas sve brže i brže. Zato kažemo da svemir ubrzava. Za razliku od niske entropije ranog svemira, iako ne znamo odgovor na ovo pitanje, bar imamo dobru teoriju koja ga objašnjava, pod uslovom da je tačna, a to je teorija o tamnoj energiji. To je ideja da sam prazan prostor ima energiju.
In every little cubic centimeter of space, whether or not there's stuff, whether or not there's particles, matter, radiation or whatever, there's still energy, even in the space itself. And this energy, according to Einstein, exerts a push on the universe. It is a perpetual impulse that pushes galaxies apart from each other. Because dark energy, unlike matter or radiation, does not dilute away as the universe expands. The amount of energy in each cubic centimeter remains the same, even as the universe gets bigger and bigger. This has crucial implications for what the universe is going to do in the future. For one thing, the universe will expand forever.
U svakom kubnom centrimetru svemira, bilo da ima nečega ili nema, bilo da ima čestica, materije, radijacije ili bilo čega, ipak ima energije, čak i u samom prostoru. I ta energija, kako Ajnštajn tvrdi, gura svemir. To je trajni impuls koji je udaljio galksije jednu od druge. Jer se tamna energija, za razliku od materije ili radijacije, ne razređuje kako se svemir širi. Količina energije u svakom kubnom centimetru ostaje ista, iako svemir postaje sve veći i veči. Ovo je od bitnog značaja za ono što će svemir raditi ubuduće. Kao prvo, svemir će se večno širiti.
Back when I was your age, we didn't know what the universe was going to do. Some people thought that the universe would recollapse in the future. Einstein was fond of this idea. But if there's dark energy, and the dark energy does not go away, the universe is just going to keep expanding forever and ever and ever. 14 billion years in the past, 100 billion dog years, but an infinite number of years into the future. Meanwhile, for all intents and purposes, space looks finite to us. Space may be finite or infinite, but because the universe is accelerating, there are parts of it we cannot see and never will see. There's a finite region of space that we have access to, surrounded by a horizon. So even though time goes on forever, space is limited to us. Finally, empty space has a temperature.
Kada sam ja bio vaših godina nismo znali šta će svemir uraditi. Neki su mislili da će se svemir urušiti u budućnosti. Ajnštajnu se sviđala ta ideja. Ali ako postoji tamna energija, i ako je trajna, svemir će se prosto širiti zauvek i uvek. To traje već 14 milijardi godina, 100 milijardi psećih godina, ali i beskonačan broj godina u budućnosti. U međuvremenu, za sve namere i svrhe, svemir nama deluje ograničeno. Svemir je možda konačan ili beskonačan, ali pošto ubrzava, postoje delovi koje ne možemo da vidimo, i nikada ih nećemo videti. Imamo pristup ograničenom delu svemira, koji je okružen horizontom. Tako da, iako se vreme večno pruža, svemir je za nas ograničen. Na kraju, prazan svemir ima temperaturu.
In the 1970s, Stephen Hawking told us that a black hole, even though you think it's black, it actually emits radiation when you take into account quantum mechanics. The curvature of space-time around the black hole brings to life the quantum mechanical fluctuation, and the black hole radiates. A precisely similar calculation by Hawking and Gary Gibbons showed that if you have dark energy in empty space, then the whole universe radiates. The energy of empty space brings to life quantum fluctuations. And so even though the universe will last forever, and ordinary matter and radiation will dilute away, there will always be some radiation, some thermal fluctuations, even in empty space. So what this means is that the universe is like a box of gas that lasts forever. Well what is the implication of that?
Sedamdesetih godina Stiven Hoking nam je rekao, da crna rupa, iako mislite da je crna, zapravo emituje radijaciju, kada uzmete u obzir kvantnu mehaniku. Zakrivljenost vremena i prostora oko crne rupe, stvara fluktuacije kvantne mehanike i crna rupa emituje radijaciju. Jako sličan proračun Hokinga i Garija Gibonsa je pokazao, da ako ima tamne energije u praznom prostoru, onda ceo svemir isijava. Energija praznog prostora stvara kvantne fluktuacije. I iako će svemir trajati večno, i obična materija i radijacija će se razrediti, uvek će biti neke radijacije, nekih termalnih fluktuacija, čak i u praznom prostoru. Dakle to znači da je svemir kao kutija gasa koja večno traje. Dakle šta to implicira?
That implication was studied by Boltzmann back in the 19th century. He said, well, entropy increases because there are many, many more ways for the universe to be high entropy, rather than low entropy. But that's a probabilistic statement. It will probably increase, and the probability is enormously huge. It's not something you have to worry about -- the air in this room all gathering over one part of the room and suffocating us. It's very, very unlikely. Except if they locked the doors and kept us here literally forever, that would happen. Everything that is allowed, every configuration that is allowed to be obtained by the molecules in this room, would eventually be obtained.
Implikacije je proučavao Boltcman u 19. veku. Rekao je da se entropija povećava jer postoji mnogo više načina da svemir ima visoku neko nisku entropiju. Ali to je izjava o verovatnoći. Verovatno će se povećati, i verovatnoća je ogromna. O tome ne brinite - da će se vazduh u sobi skupiti u jednom delu i ugušiti nas. To je vrlo malo verovatno. Osim ako bi zaključali vrata i držali nas ovde bukvalno zauvek, to bi se desilo. Sve što je moguće svaki mogući sklop molekula u ovoj sobi, će se vremenom ostvariti.
So Boltzmann says, look, you could start with a universe that was in thermal equilibrium. He didn't know about the Big Bang. He didn't know about the expansion of the universe. He thought that space and time were explained by Isaac Newton -- they were absolute; they just stuck there forever. So his idea of a natural universe was one in which the air molecules were just spread out evenly everywhere -- the everything molecules. But if you're Boltzmann, you know that if you wait long enough, the random fluctuations of those molecules will occasionally bring them into lower entropy configurations. And then, of course, in the natural course of things, they will expand back. So it's not that entropy must always increase -- you can get fluctuations into lower entropy, more organized situations.
Bolcman je rekao, počnimo od svemira koji je bio u termalnoj ravnoteži. Nije znao za Veliki prasak i širenje svemira. Mislio je da je Njutn objasnio prostor i vreme - da su apsolutni; da jednostavno postoje večno. Njegova ideja o prirodnom svemiru je ona gde su molekuli vazduha jednako raspoređeni svuda - molekuli svega. Ali ako ste Bolcman, znate da ako dovoljno čekate, nasumične fluktuacije tih molekula će ih povremeno dovesti u sklopove sa niskom entropijom. I naravno, po prirodnom toku, oni će se ponovo raširiti. Nije da se entropija mora uvek uvećavati - fluktuacije mogu imati nižu entropiju, organizovanije situacije.
Well if that's true, Boltzmann then goes onto invent two very modern-sounding ideas -- the multiverse and the anthropic principle. He says, the problem with thermal equilibrium is that we can't live there. Remember, life itself depends on the arrow of time. We would not be able to process information, metabolize, walk and talk, if we lived in thermal equilibrium. So if you imagine a very, very big universe, an infinitely big universe, with randomly bumping into each other particles, there will occasionally be small fluctuations in the lower entropy states, and then they relax back. But there will also be large fluctuations. Occasionally, you will make a planet or a star or a galaxy or a hundred billion galaxies. So Boltzmann says, we will only live in the part of the multiverse, in the part of this infinitely big set of fluctuating particles, where life is possible. That's the region where entropy is low. Maybe our universe is just one of those things that happens from time to time.
Ako je to tačno, Bolcman je onda izmislio dve vrlo savremene ideje - multiverzum i antropički princip. On kaže da je problem sa termalnom ravnotežom što mi ne možemo da živimo u njoj. Sećate se, sam život zavisi od strele vremena. Ne bismo mogli da obrađujemo informacije, razvijamo se, hodamo i pričamo, da živimo u termalnoj ravnoteži. Ako zamislite veoma veliki svemir, beskonačno veliki svemir, sa česticama koje nasumično naleću jedna na drugu, povremeno će biti malih fluktuacija u stanjima sa niskom entropijom koje će se onda ponovo opustiti. Ali će takođe biti velikih fluktuacija. Povremeno, nastaće planeta ili zvezda ili galaksija ili sto milijardi galaksija. I Bolcman kaže, živećemo samo u delu multiverzuma, u delu tog beskonačno velikog skupa fluktuacija čestica gde je život moguć. To je deo gde je entropija niska. Možda je naš svemir samo jedna od onih stvari koje se dešavaju s vremena na vreme.
Now your homework assignment is to really think about this, to contemplate what it means. Carl Sagan once famously said that "in order to make an apple pie, you must first invent the universe." But he was not right. In Boltzmann's scenario, if you want to make an apple pie, you just wait for the random motion of atoms to make you an apple pie. That will happen much more frequently than the random motions of atoms making you an apple orchard and some sugar and an oven, and then making you an apple pie. So this scenario makes predictions. And the predictions are that the fluctuations that make us are minimal. Even if you imagine that this room we are in now exists and is real and here we are, and we have, not only our memories, but our impression that outside there's something called Caltech and the United States and the Milky Way Galaxy, it's much easier for all those impressions to randomly fluctuate into your brain than for them actually to randomly fluctuate into Caltech, the United States and the galaxy.
Vaš domaći zadatak je da dobro razmislite o ovome i šta to znači. Karl Sagan je jednom rekao, "da biste napravili pitu sa jabukama, prvo morate izumeti svemir". Ali nije bio u pravu. Po Bolcmanovom scenariju, ako hoćete da napravite pitu sa jabukama, samo čekate nasumično kretanje atoma da vam napravi pitu. To će se desiti mnogo češće nego da vam nasumično kretanje atoma napravi voćnjak jabuka i malo šećera i pećnicu i onda vam napravi pitu. Dakle ovaj scenario pravi predviđanja. A, ona kažu da su fluktuacije koje nas sačinjavaju minimalne. Čak i ako zamislite da soba u kojoj smo sada postoji i da je stvarna i da smo tu, i imamo ne samo naša sećanja, već i utisak da napolju postoji nešto zvano Kaltek i Sjedinjene Države i Mlečni put, mnogo je lakše da ti utisci nasumično fluktuiraju u vaš mozak nego da zapravo nasumično fluktuiraju u Kaltek, Sjedinjene Države i galaksiju.
The good news is that, therefore, this scenario does not work; it is not right. This scenario predicts that we should be a minimal fluctuation. Even if you left our galaxy out, you would not get a hundred billion other galaxies. And Feynman also understood this. Feynman says, "From the hypothesis that the world is a fluctuation, all the predictions are that if we look at a part of the world we've never seen before, we will find it mixed up, and not like the piece we've just looked at -- high entropy. If our order were due to a fluctuation, we would not expect order anywhere but where we have just noticed it. We therefore conclude the universe is not a fluctuation." So that's good. The question is then what is the right answer? If the universe is not a fluctuation, why did the early universe have a low entropy? And I would love to tell you the answer, but I'm running out of time.
Dobra vest je da, stoga, ovaj scenario ne radi, nije tačan. Ovaj scenario predviđa da bi trebalo da budemo minimalne fluktuacije. Čak i ako izostavite našu galaksiju, nećete dobiti sto milijardi drugih galaksija. A, Fejnman je razumeo i ovo. Rekao je: "Od pretpostavke da je svet fluktuacija, sva predviđanja govore, da ako pogledamo deo sveta koji nismo ranije videli, on će biti pomešan, a ne kao deo koji smo upravo videli - visoka entropija. Ako je naš red posledica fluktuacije, očekivali bismo red samo tamo gde smo ga već primetili. Dakle zaključujemo da svemir nije fluktuacija". To je dobro. Pitanje je onda šta je pravi odgovor? Ako svemir nije fluktuacija, zašto je rani svemir imao nisku entropiju? I voleo bih da vam kažem odgovor, ali nestaje mi vremena.
(Laughter)
(Smeh)
Here is the universe that we tell you about, versus the universe that really exists. I just showed you this picture. The universe is expanding for the last 10 billion years or so. It's cooling off. But we now know enough about the future of the universe to say a lot more. If the dark energy remains around, the stars around us will use up their nuclear fuel, they will stop burning. They will fall into black holes. We will live in a universe with nothing in it but black holes. That universe will last 10 to the 100 years -- a lot longer than our little universe has lived. The future is much longer than the past. But even black holes don't last forever. They will evaporate, and we will be left with nothing but empty space. That empty space lasts essentially forever. However, you notice, since empty space gives off radiation, there's actually thermal fluctuations, and it cycles around all the different possible combinations of the degrees of freedom that exist in empty space. So even though the universe lasts forever, there's only a finite number of things that can possibly happen in the universe. They all happen over a period of time equal to 10 to the 10 to the 120 years.
Ovo je svemir o kojem vam mi pričamo, nasuprot svemiru koji zaista postoji. Upravo sam vam pokazao ovu sliku. Svemir se širi otprilike proteklilh 10 milijardi godina Hladi se. Ali znamo dovoljno o budućnosti svemira da bismo rekli mnogo više. Ako tamna energija ostaje prisutna, zvezde oko nas će potrošiti svoje nuklearno gorivo i ugasiće se. Urušiće se u crne rupe. Živećemo u svemiru u kojem postoje smao crne rupe. Taj svemir će trajati 10 na 100-ti godina - mnogo duže od našeg malog svemira. Budućnost je mnogo duža od prošlosti. Ali čak ni crne rupe ne traju večno. One će ispariti i ostaće samo prazan prostor. Taj prazan prostor u suštini traje večno. Ipak, primetićete, pošto prazan prostor emituje radijaciju, zapravo postoje termalne fluktuacije, i ciklus se ponavalja; sve moguće različite kombinacije stepena slobode koji postoje u praznom prostoru. Dakle, iako svemir traje večno, postoji samo ograničen broj stvari koje mogu da se dese u njemu. Sve se dešavaju tokom vremenskog perioda koji iznosi 10 na 10-ti na 120-ti godina.
So here's two questions for you. Number one: If the universe lasts for 10 to the 10 to the 120 years, why are we born in the first 14 billion years of it, in the warm, comfortable afterglow of the Big Bang? Why aren't we in empty space? You might say, "Well there's nothing there to be living," but that's not right. You could be a random fluctuation out of the nothingness. Why aren't you? More homework assignment for you.
Dakle, evo dva pitanja za vas. Prvo: ako svemir traje 10 na 10-ti na 120-ti godina, zašto se rađamo u njegovih prvih 14 milijardi godina, u toplom, prijatnom odsjaju Velikog praska? Zašto nismo u praznom prostoru? Možda kažete: "Pa, tamo ništa ne može da živi", ali to nije tačno. Možete biti nasumična fluktuacija iz ništavila. Zašto niste? Eto vam još domaćeg zadatka.
So like I said, I don't actually know the answer. I'm going to give you my favorite scenario. Either it's just like that. There is no explanation. This is a brute fact about the universe that you should learn to accept and stop asking questions. Or maybe the Big Bang is not the beginning of the universe. An egg, an unbroken egg, is a low entropy configuration, and yet, when we open our refrigerator, we do not go, "Hah, how surprising to find this low entropy configuration in our refrigerator." That's because an egg is not a closed system; it comes out of a chicken. Maybe the universe comes out of a universal chicken. Maybe there is something that naturally, through the growth of the laws of physics, gives rise to universe like ours in low entropy configurations. If that's true, it would happen more than once; we would be part of a much bigger multiverse. That's my favorite scenario.
Kao što rekoh, ja zapravo ne znam odgovor. Daću vam moj omiljeni scenario. Ili je to tek tako. Ne postoji objašnjenje. To je okrutna činjenica o svemiru koju treba da prihvatite i ne postavljate pitanja. Ili možda Veliki prasak nije početak svemira. Jaje, nepolomljeno jaje, je sklop niske entropije, a ipak, kada otvorimo frižider, ne pomislimo: "Kako je čudno da se nađe ovaj sklop sa niskom entropijom u mom frižideru". To je zato što jaje nije zatvoren sistem; nastaje iz kokoške. Možda svemir nastaje iz svemirske kokoške. Možda postoji nešto što prirodnim putem, kroz rast zakona fizike, stvara svemir poput našeg u sklopovima niske entropije. Ako je to tačno, desilo bi se više puta; bili bismo deo mnogo većeg multiverzuma. To je moj omiljeni scenario.
So the organizers asked me to end with a bold speculation. My bold speculation is that I will be absolutely vindicated by history. And 50 years from now, all of my current wild ideas will be accepted as truths by the scientific and external communities. We will all believe that our little universe is just a small part of a much larger multiverse. And even better, we will understand what happened at the Big Bang in terms of a theory that we will be able to compare to observations. This is a prediction. I might be wrong. But we've been thinking as a human race about what the universe was like, why it came to be in the way it did for many, many years. It's exciting to think we may finally know the answer someday.
Organizatori su me zamolili da završim sa hrabrim nagađanjem. Moje hrabro nagađanje je da će me istorija potpuno opravdati. I da će za 50 godina, sve moje lude ideje biti prihvaćene kao istine od strane naučnih i ostalih udruženja. Svi ćemo verovati da je naš mali svemir samo mali deo mnogo većeg multiverzuma. I još bolje, razumećemo šta se desilo sa Velikim praskom u pogledu teorije koju ćemo moći da poredimo sa opažanjima. To je predviđanje. Možda grešim. Ali razmišljali smo kao ljudska rasa o tome kakav je bio svemir, zašto je postao i ostao kakav jeste tokom mnogo, mnogo godina. Uzbudljivo je pomisliti da ćemo jednom konačno saznati odgovor.
Thank you.
Hvala vam.
(Applause)
(Aplauz)