Sean Carroll: Distant time and the hint of a multiverse

Prevodilac: Slavko Despotović Lektor: Ana Zivanovic-Nenadovic

The universe

Svemir

is really big.

je zaista ogroman.

We live in a galaxy, the Milky Way Galaxy.

Živimo u galaksiji Mlečni put,

There are about a hundred billion stars in the Milky Way Galaxy.

u kojoj ima oko sto milijardi zvezda.

And if you take a camera

I ako uzmete kameru

and you point it at a random part of the sky,

i uperite je bilo gde ka nebu,

and you just keep the shutter open,

i skinete poklopac,

as long as your camera is attached to the Hubble Space Telescope,

ako vam je kamera priključena na svemirski telskop Habl,

it will see something like this.

videće nešto ovako.

Every one of these little blobs

Svaka od tih malih mrlja

is a galaxy roughly the size of our Milky Way --

je galaksija veličine slične našem Mlečnom putu -

a hundred billion stars in each of those blobs.

sto milijardi zvezda u svakoj od tih mrlja.

There are approximately a hundred billion galaxies

Ima oko sto milijardi galaksija

in the observable universe.

u vidljivom svemiru.

100 billion is the only number you need to know.

Sto milijardi je jedini broj koji treba da znate.

The age of the universe, between now and the Big Bang,

Starost svemira, između Velikog praska i sadašnosti,

is a hundred billion in dog years.

je sto milijardi u psećim godinama.

(Laughter)

(Smeh)

Which tells you something about our place in the universe.

Što vam govori nešto o našem mestu u svemiru.

One thing you can do with a picture like this is simply admire it.

Jedino što možete sa ovom slikom jeste da joj se divite.

It's extremely beautiful.

Neverovatno je lepa.

I've often wondered, what is the evolutionary pressure

Često sam se pitao kakav je to pritisak evolucije

that made our ancestors in the Veldt adapt and evolve

terao naše pretke u Africi da se prilagođavaju i evoluiraju

to really enjoy pictures of galaxies

da bi uživali u slikama galaksije

when they didn't have any.

kada ih nisu imali.

But we would also like to understand it.

Ali i mi bismo voleli da razumemo to.

As a cosmologist, I want to ask, why is the universe like this?

Kao kosmolog, želim da se pitam, zašto je svemir ovakav?

One big clue we have is that the universe is changing with time.

Veliki trag koji imamo jeste da se svemir vremenom menja.

If you looked at one of these galaxies and measured its velocity,

Ako pogledate jednu od ovih galaksija i izmerite njenu brzinu,

it would be moving away from you.

ona će se udaljavati od vas.

And if you look at a galaxy even farther away,

A ako pogledate još udaljeniju galaksiju,

it would be moving away faster.

ona će se udaljavati još brže.

So we say the universe is expanding.

Zato kažemo da se svemir širi.

What that means, of course, is that, in the past,

To, naravno, znači da su u prošlosti

things were closer together.

stvari bile skupljenije.

In the past, the universe was more dense,

U prošlosti, svemir je bio gušći

and it was also hotter.

i takođe, topliji.

If you squeeze things together, the temperature goes up.

Ako sabijete stvari zajedno, temperatura raste.

That kind of makes sense to us.

To nam je nekako logično.

The thing that doesn't make sense to us as much

Ono što nije tako logično

is that the universe, at early times, near the Big Bang,

jeste da je svemir, u rano doba, blizu Velikog praska

was also very, very smooth.

takođe bio vrlo vrlo gladak.

You might think that that's not a surprise.

To vas možda ne iznenađuje.

The air in this room is very smooth.

Vazduh u ovoj sobi je vrlo gladak.

You might say, "Well, maybe things just smoothed themselves out."

Mislite: "Pa, možda su se stvari same izgladile".

But the conditions near the Big Bang are very, very different

Ali stanja blizu Velikog praska su vrlo različita

than the conditions of the air in this room.

od stanja vazduha u ovoj sobi.

In particular, things were a lot denser.

Tačnije, stvari su bile mnogo gušće.

The gravitational pull of things

Gravitacione sile

was a lot stronger near the Big Bang.

su bile mnogo jače blizu Velikog praska.

What you have to think about

Morate da shvatite

is we have a universe with a hundred billion galaxies,

da svemir ima sto milijardi galaksija,

a hundred billion stars each.

svaka sa po sto milijardi zvezda.

At early times, those hundred billion galaxies

U rano doba, tih sto milijardi galaksija

were squeezed into a region about this big --

je bilo sabijeno u prostor ove veličine -

literally -- at early times.

bukvalno, u rano doba.

And you have to imagine doing that squeezing

I zamislite to sabijanje

without any imperfections,

savršeno izvedeno,

without any little spots

bez nekih malih tačaka

where there were a few more atoms than somewhere else.

gde ima par atoma više nego negde drugde.

Because if there had been, they would have collapsed under the gravitational pull

Da je bilo tako, urušili bi se pod gravitacionim silama

into a huge black hole.

u ogromnu crnu rupu.

Keeping the universe very, very smooth at early times

Održati svemir vrlo glatkim u rano doba

is not easy; it's a delicate arrangement.

je bio vrlo delikatan zadatak.

It's a clue

To je trag

that the early universe is not chosen randomly.

da rani svemir nje bio nasumično odabran.

There is something that made it that way.

Nešto ga je učinilo takvim.

We would like to know what.

Želeli bismo da znamo šta.

So part of our understanding of this was given to us by Ludwig Boltzmann,

Ludvig Boltcman, austrijski fizičar iz 19. veka,

an Austrian physicist in the 19th century.

nam je dao delimično rešenje.

And Boltzmann's contribution was that he helped us understand entropy.

Boltcmanov doprinos je u tome što nam je pomogao da razumemo entropiju.

You've heard of entropy.

Čuli ste za entropiju.

It's the randomness, the disorder, the chaoticness of some systems.

To je nasumičnost, nered, haotičnost nekih sistema.

Boltzmann gave us a formula --

Boltzman nam je dao formulu,

engraved on his tombstone now --

koja je ugravirana na njegovom nadgrobnom spomeniku,

that really quantifies what entropy is.

koja zaista objašnjava entropiju.

And it's basically just saying

I u osnovi nam kaže

that entropy is the number of ways

da je entropija broj načina

we can rearrange the constituents of a system so that you don't notice,

na koji možemo da preuredimo delove sistema, tako da ne primetite,

so that macroscopically it looks the same.

tako da on makroskopski izgleda isto.

If you have the air in this room,

Na primer, vazduh u ovoj sobi,

you don't notice each individual atom.

ne primetite njegov svaki pojedinačni atom.

A low entropy configuration

Sklop sa niskom entropijom

is one in which there's only a few arrangements that look that way.

je onaj gde postoji samo par takvih uređenja.

A high entropy arrangement

Sklop sa visokom entropijom

is one that there are many arrangements that look that way.

je onaj gde postoji veliki broj takvih uređenja.

This is a crucially important insight

To je uvid od ključne važnosti,

because it helps us explain

jer nam pomaže da objasnimo

the second law of thermodynamics --

drugi zakon termodinamike -

the law that says that entropy increases in the universe,

zakon po kome se entropija povećava u svemiru,

or in some isolated bit of the universe.

ili u izolovanom delu svemira.

The reason why entropy increases

Entropija se povećava jer

is simply because there are many more ways

jednostavno ima mnogo više načina

to be high entropy than to be low entropy.

da se postigne visoka nego niska entropija.

That's a wonderful insight,

To je divan uvid,

but it leaves something out.

ali nešto izostavlja.

This insight that entropy increases, by the way,

Usput, uvid da se entropija povećava

is what's behind what we call the arrow of time,

objašnjava ono što nazivamo strelom vremena,

the difference between the past and the future.

razliku između prošlosti i budućnosti.

Every difference that there is

Svaka razlika

between the past and the future

između prošlosti i budućnosti

is because entropy is increasing --

postoji jer se entropija povećava -

the fact that you can remember the past, but not the future.

to što se sećate prošlosti, ali ne i budućnosti.

The fact that you are born, and then you live, and then you die,

To što se rađamo, živimo i umiremo,

always in that order,

uvek tim redom,

that's because entropy is increasing.

je zato što se entropija povećava.

Boltzmann explained that if you start with low entropy,

Boltcman je objasnio da ako se krene od niske entropije,

it's very natural for it to increase

prirodno je da se ona povećava.

because there's more ways to be high entropy.

zato što postoji više načina da se postigne visoka entropija.

What he didn't explain

Ali nije objasnio

was why the entropy was ever low in the first place.

zašto je entropija niska na početku.

The fact that the entropy of the universe was low

To što je entropija svemira bila niska

was a reflection of the fact

odražava činjenicu

that the early universe was very, very smooth.

da je rani svemir bio vrlo, vrlo gladak.

We'd like to understand that.

Hteli bismo to da razumemo.

That's our job as cosmologists.

To je posao nas kosmologa.

Unfortunately, it's actually not a problem

Nažalost, to je problem

that we've been giving enough attention to.

kome smo posvetili malo pažnje.

It's not one of the first things people would say,

On nije jedna od prvih stvari koje biste čuli

if you asked a modern cosmologist,

ako biste pitali savremenog kosmologa,

"What are the problems we're trying to address?"

"Koje probleme pokušavamo da rešimo?"

One of the people who did understand that this was a problem

Jedan od ljudi koji je shvatio da je ovo problem

was Richard Feynman.

je bio Ričard Fejnman.

50 years ago, he gave a series of a bunch of different lectures.

Pre 50 godina, održao je niz različitih predavanja.

He gave the popular lectures

Držao je popularna predavanja

that became "The Character of Physical Law."

koja su postala "Lik fizičkog zakona".

He gave lectures to Caltech undergrads

Držao je predavanja studentima na Kalteku

that became "The Feynman Lectures on Physics."

koja su postala "Fejnmanova predavanja o fizici."

He gave lectures to Caltech graduate students

Držao je predavanja diplomcima na Kalteku

that became "The Feynman Lectures on Gravitation."

koja su postala "Fejnmanova predavanja o gravitaciji"

In every one of these books, every one of these sets of lectures,

U svim tim knjigama, tim nizovima predavanja,

he emphasized this puzzle:

naglašavao je ovu zagonetku:

Why did the early universe have such a small entropy?

zašto je rani svemir imao tako nisku entropiju?

So he says -- I'm not going to do the accent --

I rekao je, neću imitirati akcenat:

he says, "For some reason, the universe, at one time,

"Iz nekog razloga, svemir je u jednom trenutku,

had a very low entropy for its energy content,

imao vrlo nisku entropiju u odnosu na njegovu energiju,

and since then the entropy has increased.

i od tada entropija se uvećala.

The arrow of time cannot be completely understood

Strela vremena se ne može u potpunosti razumeti

until the mystery of the beginnings of the history of the universe

dok se misterija o početku istorijie svemira

are reduced still further

ne svede

from speculation to understanding."

sa nagađanja na razumevanje".

So that's our job.

To je naš posao.

We want to know -- this is 50 years ago, "Surely," you're thinking,

To je bilo pre 50 godina. Vi mislite:

"we've figured it out by now."

"Sigurno smo do sada shvatili."

It's not true that we've figured it out by now.

Nije istina da smo do sada shvatili.

The reason the problem has gotten worse,

Problem je postao i teži,

rather than better,

umesto da postane lakši,

is because in 1998

jer smo 1998. godine

we learned something crucial about the universe that we didn't know before.

saznali nešto ključno o svemiru što nismo znali ranije.

We learned that it's accelerating.

Saznali smo da on ubrzava.

The universe is not only expanding.

Širenje je samo jedna karakteristika svemira.

If you look at the galaxy, it's moving away.

Pogledajte galaksiju, ona se udaljava.

If you come back a billion years later and look at it again,

Pogledajte je opet za milijardu godina,

it will be moving away faster.

i udaljavaće se još brže.

Individual galaxies are speeding away from us faster and faster

Pojedine galaksije ubrzavaju od nas sve brže i brže.

so we say the universe is accelerating.

Zato kažemo da svemir ubrzava.

Unlike the low entropy of the early universe,

Za razliku od niske entropije ranog svemira,

even though we don't know the answer for this,

iako ne znamo odgovor na ovo pitanje,

we at least have a good theory that can explain it,

bar imamo dobru teoriju koja ga objašnjava,

if that theory is right,

pod uslovom da je tačna,

and that's the theory of dark energy.

a to je teorija o tamnoj energiji.

It's just the idea that empty space itself has energy.

To je ideja da sam prazan prostor ima energiju.

In every little cubic centimeter of space,

U svakom kubnom centrimetru svemira,

whether or not there's stuff,

bilo da ima nečega ili nema,

whether or not there's particles, matter, radiation or whatever,

bilo da ima čestica, materije, radijacije ili bilo čega,

there's still energy, even in the space itself.

ipak ima energije, čak i u samom prostoru.

And this energy, according to Einstein,

I ta energija, kako Ajnštajn tvrdi,

exerts a push on the universe.

gura svemir.

It is a perpetual impulse

To je trajni impuls

that pushes galaxies apart from each other.

koji je udaljio galksije jednu od druge.

Because dark energy, unlike matter or radiation,

Jer se tamna energija, za razliku od materije ili radijacije,

does not dilute away as the universe expands.

ne razređuje kako se svemir širi.

The amount of energy in each cubic centimeter

Količina energije u svakom kubnom centimetru

remains the same,

ostaje ista,

even as the universe gets bigger and bigger.

iako svemir postaje sve veći i veči.

This has crucial implications

Ovo je od bitnog značaja

for what the universe is going to do in the future.

za ono što će svemir raditi ubuduće.

For one thing, the universe will expand forever.

Kao prvo, svemir će se večno širiti.

Back when I was your age,

Kada sam ja bio vaših godina

we didn't know what the universe was going to do.

nismo znali šta će svemir uraditi.

Some people thought that the universe would recollapse in the future.

Neki su mislili da će se svemir urušiti u budućnosti.

Einstein was fond of this idea.

Ajnštajnu se sviđala ta ideja.

But if there's dark energy, and the dark energy does not go away,

Ali ako postoji tamna energija, i ako je trajna,

the universe is just going to keep expanding forever and ever and ever.

svemir će se prosto širiti zauvek i uvek.

14 billion years in the past,

To traje već 14 milijardi godina,

100 billion dog years,

100 milijardi psećih godina,

but an infinite number of years into the future.

ali i beskonačan broj godina u budućnosti.

Meanwhile, for all intents and purposes,

U međuvremenu, za sve namere i svrhe,

space looks finite to us.

svemir nama deluje ograničeno.

Space may be finite or infinite,

Svemir je možda konačan ili beskonačan,

but because the universe is accelerating,

ali pošto ubrzava,

there are parts of it we cannot see

postoje delovi koje ne možemo da vidimo,

and never will see.

i nikada ih nećemo videti.

There's a finite region of space that we have access to,

Imamo pristup ograničenom delu svemira,

surrounded by a horizon.

koji je okružen horizontom.

So even though time goes on forever,

Tako da, iako se vreme večno pruža,

space is limited to us.

svemir je za nas ograničen.

Finally, empty space has a temperature.

Na kraju, prazan svemir ima temperaturu.

In the 1970s, Stephen Hawking told us

Sedamdesetih godina Stiven Hoking nam je rekao,

that a black hole, even though you think it's black,

da crna rupa, iako mislite da je crna,

it actually emits radiation

zapravo emituje radijaciju,

when you take into account quantum mechanics.

kada uzmete u obzir kvantnu mehaniku.

The curvature of space-time around the black hole

Zakrivljenost vremena i prostora oko crne rupe,

brings to life the quantum mechanical fluctuation,

stvara fluktuacije kvantne mehanike

and the black hole radiates.

i crna rupa emituje radijaciju.

A precisely similar calculation by Hawking and Gary Gibbons

Jako sličan proračun Hokinga i Garija Gibonsa

showed that if you have dark energy in empty space,

je pokazao, da ako ima tamne energije u praznom prostoru,

then the whole universe radiates.

onda ceo svemir isijava.

The energy of empty space

Energija praznog prostora

brings to life quantum fluctuations.

stvara kvantne fluktuacije.

And so even though the universe will last forever,

I iako će svemir trajati večno,

and ordinary matter and radiation will dilute away,

i obična materija i radijacija će se razrediti,

there will always be some radiation,

uvek će biti neke radijacije,

some thermal fluctuations,

nekih termalnih fluktuacija,

even in empty space.

čak i u praznom prostoru.

So what this means

Dakle to znači

is that the universe is like a box of gas

da je svemir kao kutija gasa

that lasts forever.

koja večno traje.

Well what is the implication of that?

Dakle šta to implicira?

That implication was studied by Boltzmann back in the 19th century.

Implikacije je proučavao Boltcman u 19. veku.

He said, well, entropy increases

Rekao je da se entropija povećava

because there are many, many more ways

jer postoji mnogo više načina

for the universe to be high entropy, rather than low entropy.

da svemir ima visoku neko nisku entropiju.

But that's a probabilistic statement.

Ali to je izjava o verovatnoći.

It will probably increase,

Verovatno će se povećati,

and the probability is enormously huge.

i verovatnoća je ogromna.

It's not something you have to worry about --

O tome ne brinite -

the air in this room all gathering over one part of the room and suffocating us.

da će se vazduh u sobi skupiti u jednom delu i ugušiti nas.

It's very, very unlikely.

To je vrlo malo verovatno.

Except if they locked the doors

Osim ako bi zaključali vrata

and kept us here literally forever,

i držali nas ovde bukvalno zauvek,

that would happen.

to bi se desilo.

Everything that is allowed,

Sve što je moguće

every configuration that is allowed to be obtained by the molecules in this room,

svaki mogući sklop molekula u ovoj sobi,

would eventually be obtained.

će se vremenom ostvariti.

So Boltzmann says, look, you could start with a universe

Bolcman je rekao, počnimo od svemira

that was in thermal equilibrium.

koji je bio u termalnoj ravnoteži.

He didn't know about the Big Bang. He didn't know about the expansion of the universe.

Nije znao za Veliki prasak i širenje svemira.

He thought that space and time were explained by Isaac Newton --

Mislio je da je Njutn objasnio prostor i vreme -

they were absolute; they just stuck there forever.

da su apsolutni; da jednostavno postoje večno.

So his idea of a natural universe

Njegova ideja o prirodnom svemiru

was one in which the air molecules were just spread out evenly everywhere --

je ona gde su molekuli vazduha jednako raspoređeni svuda -

the everything molecules.

molekuli svega.

But if you're Boltzmann, you know that if you wait long enough,

Ali ako ste Bolcman, znate da ako dovoljno čekate,

the random fluctuations of those molecules

nasumične fluktuacije tih molekula

will occasionally bring them

će ih povremeno dovesti

into lower entropy configurations.

u sklopove sa niskom entropijom.

And then, of course, in the natural course of things,

I naravno, po prirodnom toku,

they will expand back.

oni će se ponovo raširiti.

So it's not that entropy must always increase --

Nije da se entropija mora uvek uvećavati -

you can get fluctuations into lower entropy,

fluktuacije mogu imati nižu entropiju,

more organized situations.

organizovanije situacije.

Well if that's true,

Ako je to tačno,

Boltzmann then goes onto invent

Bolcman je onda izmislio

two very modern-sounding ideas --

dve vrlo savremene ideje -

the multiverse and the anthropic principle.

multiverzum i antropički princip.

He says, the problem with thermal equilibrium

On kaže da je problem sa termalnom ravnotežom

is that we can't live there.

što mi ne možemo da živimo u njoj.

Remember, life itself depends on the arrow of time.

Sećate se, sam život zavisi od strele vremena.

We would not be able to process information,

Ne bismo mogli da obrađujemo informacije,

metabolize, walk and talk,

razvijamo se, hodamo i pričamo,

if we lived in thermal equilibrium.

da živimo u termalnoj ravnoteži.

So if you imagine a very, very big universe,

Ako zamislite veoma veliki svemir,

an infinitely big universe,

beskonačno veliki svemir,

with randomly bumping into each other particles,

sa česticama koje nasumično naleću jedna na drugu,

there will occasionally be small fluctuations in the lower entropy states,

povremeno će biti malih fluktuacija u stanjima sa niskom entropijom

and then they relax back.

koje će se onda ponovo opustiti.

But there will also be large fluctuations.

Ali će takođe biti velikih fluktuacija.

Occasionally, you will make a planet

Povremeno, nastaće planeta

or a star or a galaxy

ili zvezda ili galaksija

or a hundred billion galaxies.

ili sto milijardi galaksija.

So Boltzmann says,

I Bolcman kaže,

we will only live in the part of the multiverse,

živećemo samo u delu multiverzuma,

in the part of this infinitely big set of fluctuating particles,

u delu tog beskonačno velikog skupa fluktuacija čestica

where life is possible.

gde je život moguć.

That's the region where entropy is low.

To je deo gde je entropija niska.

Maybe our universe is just one of those things

Možda je naš svemir samo jedna od onih stvari

that happens from time to time.

koje se dešavaju s vremena na vreme.

Now your homework assignment

Vaš domaći zadatak

is to really think about this, to contemplate what it means.

je da dobro razmislite o ovome i šta to znači.

Carl Sagan once famously said

Karl Sagan je jednom rekao,

that "in order to make an apple pie,

"da biste napravili pitu sa jabukama,

you must first invent the universe."

prvo morate izumeti svemir".

But he was not right.

Ali nije bio u pravu.

In Boltzmann's scenario, if you want to make an apple pie,

Po Bolcmanovom scenariju, ako hoćete da napravite pitu sa jabukama,

you just wait for the random motion of atoms

samo čekate nasumično kretanje atoma

to make you an apple pie.

da vam napravi pitu.

That will happen much more frequently

To će se desiti mnogo češće

than the random motions of atoms

nego da vam nasumično kretanje atoma

making you an apple orchard

napravi voćnjak jabuka

and some sugar and an oven,

i malo šećera i pećnicu

and then making you an apple pie.

i onda vam napravi pitu.

So this scenario makes predictions.

Dakle ovaj scenario pravi predviđanja.

And the predictions are

A, ona kažu

that the fluctuations that make us are minimal.

da su fluktuacije koje nas sačinjavaju minimalne.

Even if you imagine that this room we are in now

Čak i ako zamislite da soba u kojoj smo sada

exists and is real and here we are,

postoji i da je stvarna i da smo tu,

and we have, not only our memories,

i imamo ne samo naša sećanja,

but our impression that outside there's something

već i utisak da napolju postoji nešto

called Caltech and the United States and the Milky Way Galaxy,

zvano Kaltek i Sjedinjene Države i Mlečni put,

it's much easier for all those impressions to randomly fluctuate into your brain

mnogo je lakše da ti utisci nasumično fluktuiraju u vaš mozak

than for them actually to randomly fluctuate

nego da zapravo nasumično fluktuiraju

into Caltech, the United States and the galaxy.

u Kaltek, Sjedinjene Države i galaksiju.

The good news is that,

Dobra vest je

therefore, this scenario does not work; it is not right.

da, stoga, ovaj scenario ne radi, nije tačan.

This scenario predicts that we should be a minimal fluctuation.

Ovaj scenario predviđa da bi trebalo da budemo minimalne fluktuacije.

Even if you left our galaxy out,

Čak i ako izostavite našu galaksiju,

you would not get a hundred billion other galaxies.

nećete dobiti sto milijardi drugih galaksija.

And Feynman also understood this.

A, Fejnman je razumeo i ovo.

Feynman says, "From the hypothesis that the world is a fluctuation,

Rekao je: "Od pretpostavke da je svet fluktuacija,

all the predictions are that

sva predviđanja govore,

if we look at a part of the world we've never seen before,

da ako pogledamo deo sveta koji nismo ranije videli,

we will find it mixed up, and not like the piece we've just looked at --

on će biti pomešan, a ne kao deo koji smo upravo videli -

high entropy.

visoka entropija.

If our order were due to a fluctuation,

Ako je naš red posledica fluktuacije,

we would not expect order anywhere but where we have just noticed it.

očekivali bismo red samo tamo gde smo ga već primetili.

We therefore conclude the universe is not a fluctuation."

Dakle zaključujemo da svemir nije fluktuacija".

So that's good. The question is then what is the right answer?

To je dobro. Pitanje je onda šta je pravi odgovor?

If the universe is not a fluctuation,

Ako svemir nije fluktuacija,

why did the early universe have a low entropy?

zašto je rani svemir imao nisku entropiju?

And I would love to tell you the answer, but I'm running out of time.

I voleo bih da vam kažem odgovor, ali nestaje mi vremena.

(Laughter)

(Smeh)

Here is the universe that we tell you about,

Ovo je svemir o kojem vam mi pričamo,

versus the universe that really exists.

nasuprot svemiru koji zaista postoji.

I just showed you this picture.

Upravo sam vam pokazao ovu sliku.

The universe is expanding for the last 10 billion years or so.

Svemir se širi otprilike proteklilh 10 milijardi godina

It's cooling off.

Hladi se.

But we now know enough about the future of the universe

Ali znamo dovoljno o budućnosti svemira

to say a lot more.

da bismo rekli mnogo više.

If the dark energy remains around,

Ako tamna energija ostaje prisutna,

the stars around us will use up their nuclear fuel, they will stop burning.

zvezde oko nas će potrošiti svoje nuklearno gorivo i ugasiće se.

They will fall into black holes.

Urušiće se u crne rupe.

We will live in a universe

Živećemo u svemiru

with nothing in it but black holes.

u kojem postoje smao crne rupe.

That universe will last 10 to the 100 years --

Taj svemir će trajati 10 na 100-ti godina -

a lot longer than our little universe has lived.

mnogo duže od našeg malog svemira.

The future is much longer than the past.

Budućnost je mnogo duža od prošlosti.

But even black holes don't last forever.

Ali čak ni crne rupe ne traju večno.

They will evaporate,

One će ispariti

and we will be left with nothing but empty space.

i ostaće samo prazan prostor.

That empty space lasts essentially forever.

Taj prazan prostor u suštini traje večno.

However, you notice, since empty space gives off radiation,

Ipak, primetićete, pošto prazan prostor emituje radijaciju,

there's actually thermal fluctuations,

zapravo postoje termalne fluktuacije,

and it cycles around

i ciklus se ponavalja;

all the different possible combinations

sve moguće različite kombinacije

of the degrees of freedom that exist in empty space.

stepena slobode koji postoje u praznom prostoru.

So even though the universe lasts forever,

Dakle, iako svemir traje večno,

there's only a finite number of things

postoji samo ograničen broj stvari

that can possibly happen in the universe.

koje mogu da se dese u njemu.

They all happen over a period of time

Sve se dešavaju tokom vremenskog perioda

equal to 10 to the 10 to the 120 years.

koji iznosi 10 na 10-ti na 120-ti godina.

So here's two questions for you.

Dakle, evo dva pitanja za vas.

Number one: If the universe lasts for 10 to the 10 to the 120 years,

Prvo: ako svemir traje 10 na 10-ti na 120-ti godina,

why are we born

zašto se rađamo

in the first 14 billion years of it,

u njegovih prvih 14 milijardi godina,

in the warm, comfortable afterglow of the Big Bang?

u toplom, prijatnom odsjaju Velikog praska?

Why aren't we in empty space?

Zašto nismo u praznom prostoru?

You might say, "Well there's nothing there to be living,"

Možda kažete: "Pa, tamo ništa ne može da živi",

but that's not right.

ali to nije tačno.

You could be a random fluctuation out of the nothingness.

Možete biti nasumična fluktuacija iz ništavila.

Why aren't you?

Zašto niste?

More homework assignment for you.

Eto vam još domaćeg zadatka.

So like I said, I don't actually know the answer.

Kao što rekoh, ja zapravo ne znam odgovor.

I'm going to give you my favorite scenario.

Daću vam moj omiljeni scenario.

Either it's just like that. There is no explanation.

Ili je to tek tako. Ne postoji objašnjenje.

This is a brute fact about the universe

To je okrutna činjenica o svemiru

that you should learn to accept and stop asking questions.

koju treba da prihvatite i ne postavljate pitanja.

Or maybe the Big Bang

Ili možda Veliki prasak

is not the beginning of the universe.

nije početak svemira.

An egg, an unbroken egg, is a low entropy configuration,

Jaje, nepolomljeno jaje, je sklop niske entropije,

and yet, when we open our refrigerator,

a ipak, kada otvorimo frižider,

we do not go, "Hah, how surprising to find

ne pomislimo: "Kako je čudno da se nađe

this low entropy configuration in our refrigerator."

ovaj sklop sa niskom entropijom u mom frižideru".

That's because an egg is not a closed system;

To je zato što jaje nije zatvoren sistem;

it comes out of a chicken.

nastaje iz kokoške.

Maybe the universe comes out of a universal chicken.

Možda svemir nastaje iz svemirske kokoške.

Maybe there is something that naturally,

Možda postoji nešto što prirodnim putem,

through the growth of the laws of physics,

kroz rast zakona fizike,

gives rise to universe like ours

stvara svemir poput našeg

in low entropy configurations.

u sklopovima niske entropije.

If that's true, it would happen more than once;

Ako je to tačno, desilo bi se više puta;

we would be part of a much bigger multiverse.

bili bismo deo mnogo većeg multiverzuma.

That's my favorite scenario.

To je moj omiljeni scenario.

So the organizers asked me to end with a bold speculation.

Organizatori su me zamolili da završim sa hrabrim nagađanjem.

My bold speculation

Moje hrabro nagađanje

is that I will be absolutely vindicated by history.

je da će me istorija potpuno opravdati.

And 50 years from now,

I da će za 50 godina,

all of my current wild ideas will be accepted as truths

sve moje lude ideje biti prihvaćene kao istine

by the scientific and external communities.

od strane naučnih i ostalih udruženja.

We will all believe that our little universe

Svi ćemo verovati da je naš mali svemir

is just a small part of a much larger multiverse.

samo mali deo mnogo većeg multiverzuma.

And even better, we will understand what happened at the Big Bang

I još bolje, razumećemo šta se desilo sa Velikim praskom

in terms of a theory

u pogledu teorije

that we will be able to compare to observations.

koju ćemo moći da poredimo sa opažanjima.

This is a prediction. I might be wrong.

To je predviđanje. Možda grešim.

But we've been thinking as a human race

Ali razmišljali smo kao ljudska rasa

about what the universe was like,

o tome kakav je bio svemir,

why it came to be in the way it did for many, many years.

zašto je postao i ostao kakav jeste tokom mnogo, mnogo godina.

It's exciting to think we may finally know the answer someday.

Uzbudljivo je pomisliti da ćemo jednom konačno saznati odgovor.

Thank you.

Hvala vam.

(Applause)

(Aplauz)