TEDxCaltech
Sean Carroll: Distant time and the hint of a multiverse
Sean Carroll: Daleko vrijeme i naznaka multisvemira
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Na TEDxCaltech, kozmolog Sean Carroll napada -- u zanimljivoj priči o prirodi vremena i svemira -- naoko jednostavno pitanje: Zašto postoji vrijeme? Mogući odgovori ukazuju na iznenađujuću prirodu svemira, i naše uloge u njemu.
Sean M. Carroll - Physicist, cosmologist
A physicist, cosmologist and gifted science communicator, Sean Carroll is asking himself -- and asking us to consider -- questions that get at the fundamental nature of the universe. Full bio
A physicist, cosmologist and gifted science communicator, Sean Carroll is asking himself -- and asking us to consider -- questions that get at the fundamental nature of the universe. Full bio
Double-click the English transcript below to play the video.
00:15
The universe
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Svemir
00:17
is really big.
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je jako velik.
00:19
We live in a galaxy, the Milky Way Galaxy.
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Živimo u galaksiji Mliječni put.
00:22
There are about a hundred billion stars in the Milky Way Galaxy.
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U njoj ima oko sto milijardi zvijezda.
00:25
And if you take a camera
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Ako uzmete kameru
00:27
and you point it at a random part of the sky,
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i uperite je u nasumični komad neba,
00:29
and you just keep the shutter open,
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i ostavite zatvarač otvorenim,
00:31
as long as your camera is attached to the Hubble Space Telescope,
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i ako vam je kamera spojena na teleskop Hubble,
00:34
it will see something like this.
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vidjet će ovakvo nešto.
00:36
Every one of these little blobs
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Svaka mrlja je galaksija
00:39
is a galaxy roughly the size of our Milky Way --
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veličine Mliječnog puta --
00:41
a hundred billion stars in each of those blobs.
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u svakoj oko sto milijardi zvijezda.
00:44
There are approximately a hundred billion galaxies
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Postoji oko sto milijardi galaksija
00:47
in the observable universe.
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u vidljivom svemiru.
00:49
100 billion is the only number you need to know.
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Sto milijardi je jedini broj.
00:51
The age of the universe, between now and the Big Bang,
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Starost Svemira, od sad do Velikog Praska,
00:54
is a hundred billion in dog years.
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je sto milijardi u psećim godinama.
00:56
(Laughter)
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(Smijeh)
00:58
Which tells you something about our place in the universe.
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Što vam govori nešto o našem značaju u svemiru.
01:01
One thing you can do with a picture like this is simply admire it.
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Ovoj slici se divimo.
01:03
It's extremely beautiful.
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Jako je lijepa.
01:05
I've often wondered, what is the evolutionary pressure
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Pitao sam se, kakav evolucijski pritisak
01:08
that made our ancestors in the Veldt adapt and evolve
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je natjerao naše pretke u Veldt ravnicama da evoluiraju
01:11
to really enjoy pictures of galaxies
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da im se sviđaju slike galaksija
01:13
when they didn't have any.
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dok ih nisu imali.
01:15
But we would also like to understand it.
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Ali ih želimo razumjeti.
01:17
As a cosmologist, I want to ask, why is the universe like this?
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Kao kozmolog se pitam, zašto je svemir ovakav?
01:21
One big clue we have is that the universe is changing with time.
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Veliki trag je da se svemir mijenja s vremenom.
01:24
If you looked at one of these galaxies and measured its velocity,
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Ako gledate jednu galaksiju, i mjerite joj brzinu,
01:27
it would be moving away from you.
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ona se kreće od vas.
01:29
And if you look at a galaxy even farther away,
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Ako gledate još dalju galaksiju
01:31
it would be moving away faster.
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ona se kreće još brže.
01:33
So we say the universe is expanding.
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Zato kažemo da se svemir širi.
01:35
What that means, of course, is that, in the past,
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To znači da su u prošlosti
01:37
things were closer together.
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stvari bile međusobno bliže.
01:39
In the past, the universe was more dense,
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U prošlosti je svemir bio gušći,
01:41
and it was also hotter.
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i topliji.
01:43
If you squeeze things together, the temperature goes up.
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Ako nešto stisneš, temperatura raste.
01:45
That kind of makes sense to us.
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To ima smisla.
01:47
The thing that doesn't make sense to us as much
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Ono što nema smisla
01:49
is that the universe, at early times, near the Big Bang,
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je da je svemir, jako rano, blizu Velikog Praska,
01:52
was also very, very smooth.
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bio jako gladak.
01:54
You might think that that's not a surprise.
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To nije iznenađujuće.
01:56
The air in this room is very smooth.
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Zrak u ovoj sobi je jako gladak.
01:58
You might say, "Well, maybe things just smoothed themselves out."
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Kažete, "Možda su se stvari izgladile."
02:01
But the conditions near the Big Bang are very, very different
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Ali uvjeti blizu Velikog Praska su puno drugačiji
02:04
than the conditions of the air in this room.
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nego uvjeti zraka u ovoj sobi.
02:06
In particular, things were a lot denser.
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Stvari su bile puno gušće.
02:08
The gravitational pull of things
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Gravitacijska privlačnost
02:10
was a lot stronger near the Big Bang.
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je bila jaka blizu Velikog Praska.
02:12
What you have to think about
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Morate znati
02:14
is we have a universe with a hundred billion galaxies,
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da imamo svemir sa sto milijardi galaksija,
02:16
a hundred billion stars each.
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svaka sa sto milijardi zvijeda.
02:18
At early times, those hundred billion galaxies
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U rana vremena, tih sto milijardi galaksija
02:21
were squeezed into a region about this big --
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je bilo stješnjeno
02:24
literally -- at early times.
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u ovoliki prostor.
02:26
And you have to imagine doing that squeezing
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Zamislite to stješnjavanje
02:28
without any imperfections,
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bez ikakvih nesavršenosti,
02:30
without any little spots
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bez ikakvih točkica
02:32
where there were a few more atoms than somewhere else.
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s više atoma nego drugdje.
02:34
Because if there had been, they would have collapsed under the gravitational pull
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Jer da je bilo, sve bi se urušilo zbog gravitacije
02:37
into a huge black hole.
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u veliku crnu rupu.
02:39
Keeping the universe very, very smooth at early times
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Držanje svemira vrlo glatkim tako rano
02:42
is not easy; it's a delicate arrangement.
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nije lako, to je osjetljiv raspored.
02:44
It's a clue
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To je indicija
02:46
that the early universe is not chosen randomly.
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da rani svemir nije odabran slučajno.
02:48
There is something that made it that way.
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Nešto ga je takvim napravilo.
02:50
We would like to know what.
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Željeli bi znati što.
02:52
So part of our understanding of this was given to us by Ludwig Boltzmann,
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Dio shvaćanja ovoga nam je dao Ludwig Boltzmann,
02:55
an Austrian physicist in the 19th century.
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Austrijski fizičar 19. stoljeća.
02:58
And Boltzmann's contribution was that he helped us understand entropy.
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Boltzmanov doprinos je bio shvaćanje entropije.
03:01
You've heard of entropy.
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Čuli ste za entropiju.
03:03
It's the randomness, the disorder, the chaoticness of some systems.
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To je slučajnost, nered, kaotičnost sistema.
03:06
Boltzmann gave us a formula --
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Boltzmann nam je dao formulu --
03:08
engraved on his tombstone now --
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ugraviranu na njegov nadgrobni kamen --
03:10
that really quantifies what entropy is.
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koja kvantificira entropiju.
03:12
And it's basically just saying
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I ona kaže
03:14
that entropy is the number of ways
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da je entropija suma načina na koji
03:16
we can rearrange the constituents of a system so that you don't notice,
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možemo preurediti sustav da se to ne primjeti,
03:19
so that macroscopically it looks the same.
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da makroskopski izgleda jednako.
03:21
If you have the air in this room,
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Imamo zrak u ovoj sobi,
03:23
you don't notice each individual atom.
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ne primjećujete zasebne atome.
03:26
A low entropy configuration
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Kod konfiguracije niske entropije
03:28
is one in which there's only a few arrangements that look that way.
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imamo tek nekoliko razmještaja koji izgledaju jednako.
03:30
A high entropy arrangement
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Kod visoke entropije
03:32
is one that there are many arrangements that look that way.
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imamo puno razmještaja koji izgledaju jednako.
03:34
This is a crucially important insight
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Ovo je presudno važan uvid,
03:36
because it helps us explain
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jer nam objašnjava
03:38
the second law of thermodynamics --
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drugi zakon termodinamike --
03:40
the law that says that entropy increases in the universe,
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zakon koji kaže da se entropija povećava u svemiru,
03:43
or in some isolated bit of the universe.
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ili u izoliranom dijelu svemira.
03:45
The reason why entropy increases
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Entropija se povećava
03:47
is simply because there are many more ways
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jer ima puno više načina
03:50
to be high entropy than to be low entropy.
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da budeš visoke nego niske entropije.
03:52
That's a wonderful insight,
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Ovo je divan uvid,
03:54
but it leaves something out.
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ali nešto izostavlja.
03:56
This insight that entropy increases, by the way,
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Ovo mišljenje da se entropija povećava,
03:58
is what's behind what we call the arrow of time,
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stoji iza vremenskog pravca,
04:01
the difference between the past and the future.
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razlike između prošlosti i budućnosti.
04:03
Every difference that there is
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Svaka promjena koja postoji
04:05
between the past and the future
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između prošlosti i budućnosti
04:07
is because entropy is increasing --
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jest uslijed povećanja entropije --
04:09
the fact that you can remember the past, but not the future.
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činjenica da se možemo sjetiti prošlosti, a ne budućnosti.
04:12
The fact that you are born, and then you live, and then you die,
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Činjenica da ste rođeni, pa živite, i onda umrete,
04:15
always in that order,
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uvijek u tom slijedu,
04:17
that's because entropy is increasing.
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jest zbog povećavajuće entropije.
04:19
Boltzmann explained that if you start with low entropy,
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Boltzmann je objasnio da ako počnete s malom entropijom,
04:21
it's very natural for it to increase
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prirodno je da se povećava,
04:23
because there's more ways to be high entropy.
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jer postoji više načina da bude visoka entropija.
04:26
What he didn't explain
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Ono što nije objasnio
04:28
was why the entropy was ever low in the first place.
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jest zašto je entropija na početku bila niska.
04:31
The fact that the entropy of the universe was low
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Ta činjenica
04:33
was a reflection of the fact
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ogledava činjenicu
04:35
that the early universe was very, very smooth.
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da je rani svemir bio gladak.
04:37
We'd like to understand that.
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Želimo to razumjeti.
04:39
That's our job as cosmologists.
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To je posao kozmologa.
04:41
Unfortunately, it's actually not a problem
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Tom problemu
04:43
that we've been giving enough attention to.
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nismo davali dosta pažnje.
04:45
It's not one of the first things people would say,
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To nije stvar koju bi prvu rekao
04:47
if you asked a modern cosmologist,
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da ste pitali kozmologa
04:49
"What are the problems we're trying to address?"
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"Koje probleme pokušavate rješiti?"
04:51
One of the people who did understand that this was a problem
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Jedan od ljudi koji su to razumjeli
04:53
was Richard Feynman.
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bio je Richard Feynman.
04:55
50 years ago, he gave a series of a bunch of different lectures.
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Prije 50 godina, dao je niz predavanja.
04:57
He gave the popular lectures
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Popularna predavanja
04:59
that became "The Character of Physical Law."
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koja su postala "Osobitosti fizikalnih zakona."
05:01
He gave lectures to Caltech undergrads
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Davao je predavanja studentima Caltecha
05:03
that became "The Feynman Lectures on Physics."
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koja su postala "Feynmanova predavanja o fizici."
05:05
He gave lectures to Caltech graduate students
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Davao je predavanja diplomcima
05:07
that became "The Feynman Lectures on Gravitation."
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koja su postala "Feynmanova predavanja o gravitaciji."
05:09
In every one of these books, every one of these sets of lectures,
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I u svakom predavanju
05:12
he emphasized this puzzle:
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naglašavao je zagonetku:
05:14
Why did the early universe have such a small entropy?
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Zašto je rani svemir imao malu entropiju?
05:17
So he says -- I'm not going to do the accent --
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Pa kaže -- neću imitirati naglasak --
05:19
he says, "For some reason, the universe, at one time,
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kaže, "Iz nekog razloga je svemir,
05:22
had a very low entropy for its energy content,
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imao malu entropiju za istu količinu energije,
05:25
and since then the entropy has increased.
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i entropija se povećavala.
05:27
The arrow of time cannot be completely understood
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Pravac vremena se ne može shvatiti
05:30
until the mystery of the beginnings of the history of the universe
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dok se misterij početaka povijesti svemira
05:33
are reduced still further
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ne svede s nagađanja
05:35
from speculation to understanding."
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na razumjevanje."
05:37
So that's our job.
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To je naš posao.
05:39
We want to know -- this is 50 years ago, "Surely," you're thinking,
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To je bilo prije 50 godina, mislite
05:41
"we've figured it out by now."
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"sigurno smo to već shvatili."
05:43
It's not true that we've figured it out by now.
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Još nismo shvatili.
05:45
The reason the problem has gotten worse,
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Razlog zašto se problem
05:47
rather than better,
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još pogoršao
05:49
is because in 1998
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je zato što smo 1998.
05:51
we learned something crucial about the universe that we didn't know before.
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naučili nešto presudno o svemiru.
05:54
We learned that it's accelerating.
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Naučili smo da se ubrzava.
05:56
The universe is not only expanding.
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Ne samo to.
05:58
If you look at the galaxy, it's moving away.
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Galaksije se odmiču.
06:00
If you come back a billion years later and look at it again,
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Nakon milijardu godina opet pogledaš,
06:02
it will be moving away faster.
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odmiču se još brže.
06:05
Individual galaxies are speeding away from us faster and faster
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Galaksije se odmiču sve brže i brže.
06:08
so we say the universe is accelerating.
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Kažemo da se svemir ubrzava.
06:10
Unlike the low entropy of the early universe,
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Za razliku od male entropije ranog svemira,
06:12
even though we don't know the answer for this,
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makar ne znamo odgovor na to,
06:14
we at least have a good theory that can explain it,
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imamo dobru teoriju koja to objašnjava,
06:16
if that theory is right,
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ako je točna
06:18
and that's the theory of dark energy.
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a to je teorija tamne energije.
06:20
It's just the idea that empty space itself has energy.
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Kaže da prazan prostor ima energiju.
06:23
In every little cubic centimeter of space,
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U svakom kubičnom centimetru,
06:26
whether or not there's stuff,
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bilo ili ne bilo stvari,
06:28
whether or not there's particles, matter, radiation or whatever,
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čestica, materije, zračenja, svejedno,
06:30
there's still energy, even in the space itself.
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ima energije, u samom prostoru.
06:33
And this energy, according to Einstein,
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Ova energija, po Einsteinu,
06:35
exerts a push on the universe.
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vrši guranje na svemir.
06:38
It is a perpetual impulse
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To je neprekidan impuls
06:40
that pushes galaxies apart from each other.
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koji gura galaksije jednu od druge.
06:42
Because dark energy, unlike matter or radiation,
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Tamna energija se, za razliku od materije ili zračenja,
06:45
does not dilute away as the universe expands.
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ne razrjeđuje kako se svemir širi.
06:48
The amount of energy in each cubic centimeter
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Količina energije u svakom kubičnom centimetru
06:50
remains the same,
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ostaje ista,
06:52
even as the universe gets bigger and bigger.
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kako se svemir povećava.
06:54
This has crucial implications
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Ovo ima presudne implikacije
06:57
for what the universe is going to do in the future.
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na to što će svemir napraviti u budućnosti.
07:00
For one thing, the universe will expand forever.
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Kao prvo, svemir će se širiti zauvijek.
07:02
Back when I was your age,
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Kad sam bio vaših godina,
07:04
we didn't know what the universe was going to do.
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nismo znali što će svemir napraviti.
07:06
Some people thought that the universe would recollapse in the future.
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Neki su mislili da će se svemir u budućnosti sažeti.
07:09
Einstein was fond of this idea.
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Einsteinu se sviđala ova ideja.
07:11
But if there's dark energy, and the dark energy does not go away,
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Ali ako imamo tamnu energiju, i ona ne odlazi,
07:14
the universe is just going to keep expanding forever and ever and ever.
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svemir će se širiti sve više.
07:17
14 billion years in the past,
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Prošlih 14 milijardi godina,
07:19
100 billion dog years,
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100 milijardi psećih godina,
07:21
but an infinite number of years into the future.
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i bezbroj godina u budućnost.
07:24
Meanwhile, for all intents and purposes,
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U međuvremenu, nama,
07:27
space looks finite to us.
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svemir izgleda konačno.
07:29
Space may be finite or infinite,
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Konačan ili beskonačan,
07:31
but because the universe is accelerating,
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pošto se ubrzava,
07:33
there are parts of it we cannot see
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djelove ne možemo vidjeti
07:35
and never will see.
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i nećemo nikad vidjeti.
07:37
There's a finite region of space that we have access to,
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Imamo pristup dijelu svemira,
07:39
surrounded by a horizon.
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zaokruženog horizontom.
07:41
So even though time goes on forever,
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Dakle iako vrijeme ide zauvijek,
07:43
space is limited to us.
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svemir nam je ograničen.
07:45
Finally, empty space has a temperature.
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Na kraju, prazan svemir ima temperaturu.
07:48
In the 1970s, Stephen Hawking told us
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U 1970-ima, Stephen Hawking je rekao
07:50
that a black hole, even though you think it's black,
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kako crna rupa
07:52
it actually emits radiation
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emitira zračenje,
07:54
when you take into account quantum mechanics.
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kad uzmete u obzir kvantnu mehaniku.
07:56
The curvature of space-time around the black hole
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Zakrivljenost vrijeme-prostor oko crne rupe
07:59
brings to life the quantum mechanical fluctuation,
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oživljava kvantnomehaničku fluktuaciju,
08:02
and the black hole radiates.
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i crna rupa zrači.
08:04
A precisely similar calculation by Hawking and Gary Gibbons
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Sličan račun Hawkinga i Gary Gibbonsa je pokazao
08:07
showed that if you have dark energy in empty space,
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da ako imamo tamnu energiju u praznom prostoru,
08:10
then the whole universe radiates.
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onda cijeli svemir zrači.
08:13
The energy of empty space
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Energija praznog prostora
08:15
brings to life quantum fluctuations.
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oživljava kvantne fluktuacije.
08:17
And so even though the universe will last forever,
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Dakle iako će svemir trajati vječno,
08:19
and ordinary matter and radiation will dilute away,
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obična materija i zračenje će se razrijediti,
08:22
there will always be some radiation,
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uvijek će biti nešto zračenja,
08:24
some thermal fluctuations,
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nešto termičkih fluktuacija,
08:26
even in empty space.
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čak i u praznom prostoru.
08:28
So what this means
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To znači
08:30
is that the universe is like a box of gas
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da je svemir kao kutija plina
08:32
that lasts forever.
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koja traje zauvijek.
08:34
Well what is the implication of that?
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Koje su implikacije toga?
08:36
That implication was studied by Boltzmann back in the 19th century.
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Te implikacije je proučavao Boltzmann još u 19. stoljeću.
08:39
He said, well, entropy increases
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Rekao je da se entropija povećava
08:42
because there are many, many more ways
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jer ima puno više načina
08:44
for the universe to be high entropy, rather than low entropy.
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za svemir da bude više, nego niže entropije.
08:47
But that's a probabilistic statement.
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To je vjerojatnosna izjava.
08:50
It will probably increase,
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Vjerojatno će se povećati,
08:52
and the probability is enormously huge.
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i vjerojatnost je golema.
08:54
It's not something you have to worry about --
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Ne treba se brinuti da će se
08:56
the air in this room all gathering over one part of the room and suffocating us.
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zrak u ovoj sobi skupiti na jednu stranu sobe i ugušiti nas.
09:00
It's very, very unlikely.
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To je vrlo nevjerojatno.
09:02
Except if they locked the doors
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Osim ako
09:04
and kept us here literally forever,
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nas drže ovdje zauvijek,
09:06
that would happen.
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to bi se dogodilo.
09:08
Everything that is allowed,
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Sve što je moguće,
09:10
every configuration that is allowed to be obtained by the molecules in this room,
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svaka postava koju je moguće postići molekulama u sobi,
09:13
would eventually be obtained.
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će se jednom postići.
09:15
So Boltzmann says, look, you could start with a universe
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Boltzmann kaže, možeš početi sa svemirom
09:18
that was in thermal equilibrium.
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koji je u termičkoj ravnoteži.
09:20
He didn't know about the Big Bang. He didn't know about the expansion of the universe.
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On nije znao o Velikom Prasku. Nije znao o širenju svemira.
09:23
He thought that space and time were explained by Isaac Newton --
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Mislio je da je prostor i vrijeme objasnio Isaac Newton --
09:26
they were absolute; they just stuck there forever.
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da su apsolutni; zaglavljeni zauvijek.
09:28
So his idea of a natural universe
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Njegova ideja o prirodnom svemiru
09:30
was one in which the air molecules were just spread out evenly everywhere --
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kaže da su molekule zraka raspoređene jednoliko --
09:33
the everything molecules.
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molekule svega.
09:35
But if you're Boltzmann, you know that if you wait long enough,
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Ali Boltzmann zna da ako dovoljno čekaš,
09:38
the random fluctuations of those molecules
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slučajne fluktuacije molekula
09:41
will occasionally bring them
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će ih ponekad dovesti
09:43
into lower entropy configurations.
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u konfiguraciju niske entropije.
09:45
And then, of course, in the natural course of things,
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Tada će se, prirodno,
09:47
they will expand back.
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natrag proširiti.
09:49
So it's not that entropy must always increase --
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Ne treba se entropija uvijek povećavati --
09:51
you can get fluctuations into lower entropy,
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ponekad će fluktuirati u nižu entropiju,
09:54
more organized situations.
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organiziraniju situaciju.
09:56
Well if that's true,
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Ako je to istina,
09:58
Boltzmann then goes onto invent
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Boltzmann nadalje nalazi
10:00
two very modern-sounding ideas --
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dvije moderne ideje --
10:02
the multiverse and the anthropic principle.
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multisvemir i antropički princip.
10:05
He says, the problem with thermal equilibrium
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Kaže, problem s termičkom ravnotežom
10:07
is that we can't live there.
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jest da ne omogućuje život.
10:09
Remember, life itself depends on the arrow of time.
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Život ovisi o pravcu vremena.
10:12
We would not be able to process information,
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Ne bi mogli procesirati informacije,
10:14
metabolize, walk and talk,
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metabolirati, hodati i pričati,
10:16
if we lived in thermal equilibrium.
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da živimo u termičkoj ravnoteži.
10:18
So if you imagine a very, very big universe,
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Zamislite velik svemir,
10:20
an infinitely big universe,
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beskonačno velik
10:22
with randomly bumping into each other particles,
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sa česticama koje se sudaraju,
10:24
there will occasionally be small fluctuations in the lower entropy states,
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ponekad će biti malo fluktuacija u stanju niske entropije,
10:27
and then they relax back.
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i onda se opet smire.
10:29
But there will also be large fluctuations.
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Ali bit će i velikih fluktuacija.
10:31
Occasionally, you will make a planet
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Ponekad će nastati planet
10:33
or a star or a galaxy
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ili zvijezda ili galaksija
10:35
or a hundred billion galaxies.
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ili sto milijardi galaksija.
10:37
So Boltzmann says,
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Boltzmann kaže,
10:39
we will only live in the part of the multiverse,
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živimo u dijelu multisvemira,
10:42
in the part of this infinitely big set of fluctuating particles,
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u dijelu tog beskonačno velikog seta čestica,
10:45
where life is possible.
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gdje je život moguć.
10:47
That's the region where entropy is low.
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To je predio gdje je entropija niska.
10:49
Maybe our universe is just one of those things
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Možda je naš svemir događaj
10:52
that happens from time to time.
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koji se desi s vremena na vrijeme.
10:54
Now your homework assignment
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Za zadaću
10:56
is to really think about this, to contemplate what it means.
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malo razmislite o tome.
10:58
Carl Sagan once famously said
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Carl Sagan je rekao
11:00
that "in order to make an apple pie,
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"kako bi napravili pitu od jabuke,
11:02
you must first invent the universe."
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prvo morate napraviti svemir."
11:05
But he was not right.
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Ali nije bio u pravu.
11:07
In Boltzmann's scenario, if you want to make an apple pie,
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Po Boltzmannu, ako želite napraviti pitu od jabuke,
11:10
you just wait for the random motion of atoms
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samo čekajte nasumično gibanje atoma
11:13
to make you an apple pie.
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da složi pitu od jabuke.
11:15
That will happen much more frequently
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To će se dogoditi češće
11:17
than the random motions of atoms
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nego da nasumično gibanje atoma
11:19
making you an apple orchard
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napravi voćnjak od jabuka
11:21
and some sugar and an oven,
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i šećer i pećnicu,
11:23
and then making you an apple pie.
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i onda vam napravi pitu od jabuke.
11:25
So this scenario makes predictions.
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Taj scenarij predviđa
11:28
And the predictions are
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da su fluktuacije
11:30
that the fluctuations that make us are minimal.
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koje nas stvaraju minimalne.
11:33
Even if you imagine that this room we are in now
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Ako zamislite da ova soba postoji
11:36
exists and is real and here we are,
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i stvarna je, i mi smo tu,
11:38
and we have, not only our memories,
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i imamo, ne samo sjećanje,
11:40
but our impression that outside there's something
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nego utisak da vani ima nečega
11:42
called Caltech and the United States and the Milky Way Galaxy,
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kao Caltech i Sjedinjene države i Mliječni put,
11:46
it's much easier for all those impressions to randomly fluctuate into your brain
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puno je lakše da ti utisci nasumično fluktuiraju u naš mozak
11:49
than for them actually to randomly fluctuate
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nego da nasumično fluktuiraju
11:51
into Caltech, the United States and the galaxy.
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u Caltech, Sjedinjene države i galaksiju.
11:54
The good news is that,
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Dobra je vijest
11:56
therefore, this scenario does not work; it is not right.
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da ovaj scenarij ne radi, nije točan.
11:59
This scenario predicts that we should be a minimal fluctuation.
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On predviđa da smo minimalna fluktuacija.
12:02
Even if you left our galaxy out,
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I ako dobimo galaksiju,
12:04
you would not get a hundred billion other galaxies.
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ne bi dobili sto milijardi drugih galaksija.
12:06
And Feynman also understood this.
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Feynman je to razumio.
12:08
Feynman says, "From the hypothesis that the world is a fluctuation,
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On kaže, "Od hipoteze da je svijet fluktuacija,
12:12
all the predictions are that
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svi predviđaju da ako pogledamo
12:14
if we look at a part of the world we've never seen before,
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dio svijeta koji prije nismo vidjeli,
12:16
we will find it mixed up, and not like the piece we've just looked at --
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bit će zbrkan i neće biti poput dijela koji smo sada pogledali --
12:18
high entropy.
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visoka entropija.
12:20
If our order were due to a fluctuation,
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Da je red tu uslijed fluktuacije,
12:22
we would not expect order anywhere but where we have just noticed it.
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ne bi očekivali red nigdje drugdje.
12:24
We therefore conclude the universe is not a fluctuation."
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Tako zaključujemo da svemir nije fluktuacija."
12:28
So that's good. The question is then what is the right answer?
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To je dobro. Ali koji je onda odgovor?
12:31
If the universe is not a fluctuation,
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Ako svemir nije fluktuacija,
12:33
why did the early universe have a low entropy?
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zašto je rani svemir imao nisku entropiju?
12:36
And I would love to tell you the answer, but I'm running out of time.
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Volio bih vam odgovoriti, ali ponestaje mi vremena.
12:39
(Laughter)
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(Smijeh)
12:41
Here is the universe that we tell you about,
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Ovo je svemir o kojem vam govorimo,
12:43
versus the universe that really exists.
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nasuprot svemira koji jest.
12:45
I just showed you this picture.
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Pokazao sam ovu sliku.
12:47
The universe is expanding for the last 10 billion years or so.
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Svemir se širi posljednjih 10 milijardi godina.
12:49
It's cooling off.
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Hladi se.
12:51
But we now know enough about the future of the universe
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Ali sad znamo puno više
12:53
to say a lot more.
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o budućnosti svemira.
12:55
If the dark energy remains around,
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Ako tamna energija ostane,
12:57
the stars around us will use up their nuclear fuel, they will stop burning.
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zvijezde oko nas će iskoristiti svoje gorivo, ugasiti će se.
13:00
They will fall into black holes.
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Past će u crne rupe.
13:02
We will live in a universe
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Živjet ćemo u svemiru
13:04
with nothing in it but black holes.
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s ničim osim crnih rupa.
13:06
That universe will last 10 to the 100 years --
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Takav svemir će trajati 10 do 100 godina --
13:10
a lot longer than our little universe has lived.
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puno duže nego je dosada živio.
13:12
The future is much longer than the past.
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Budućnost je puno duža od prošlosti.
13:14
But even black holes don't last forever.
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Ni crne rupe ne traju zauvijek.
13:16
They will evaporate,
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Isparit će,
13:18
and we will be left with nothing but empty space.
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i ostat će nam samo prazan svemir.
13:20
That empty space lasts essentially forever.
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Taj prazan prostor traje zauvijek.
13:24
However, you notice, since empty space gives off radiation,
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Ali prazan svemir zrači,
13:27
there's actually thermal fluctuations,
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ima termičke fluktuacije,
13:29
and it cycles around
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i vrti se
13:31
all the different possible combinations
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u svim mogućim kombinacijama
13:33
of the degrees of freedom that exist in empty space.
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koje su moguće u praznom svemiru.
13:36
So even though the universe lasts forever,
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Iako svemir traje vječno,
13:38
there's only a finite number of things
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postoji konačan broj stvari
13:40
that can possibly happen in the universe.
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koje se mogu dogoditi u njemu.
13:42
They all happen over a period of time
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Sve se dogode u vremenu
13:44
equal to 10 to the 10 to the 120 years.
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od 10 na 10 na 120 godina.
13:47
So here's two questions for you.
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Evo pitanja.
13:49
Number one: If the universe lasts for 10 to the 10 to the 120 years,
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Prvo: ako svemir toliko traje,
13:52
why are we born
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zašto se rađamo
13:54
in the first 14 billion years of it,
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u prvih 14 milijardi godina,
13:57
in the warm, comfortable afterglow of the Big Bang?
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u toplom rumenilu nakon Velikog Praska?
14:00
Why aren't we in empty space?
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Zašto nismo u praznom svemiru?
14:02
You might say, "Well there's nothing there to be living,"
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Reći ćete, "Tamo ništa ne živi,"
14:04
but that's not right.
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to nije točno.
14:06
You could be a random fluctuation out of the nothingness.
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Mogli bi biti nasumična fluktuacija iz ničega.
14:08
Why aren't you?
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Zašto nismo?
14:10
More homework assignment for you.
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Više zadaće za vas.
14:13
So like I said, I don't actually know the answer.
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Ja ne znam odgovor.
14:15
I'm going to give you my favorite scenario.
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Ovo je moj najdraži scenarij.
14:17
Either it's just like that. There is no explanation.
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Ili je tako, bez objašnjenja.
14:20
This is a brute fact about the universe
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To je činjenica o svemiru
14:22
that you should learn to accept and stop asking questions.
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koju trebate naučiti.
14:26
Or maybe the Big Bang
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Ili Veliki Prasak
14:28
is not the beginning of the universe.
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nije početak svemira.
14:30
An egg, an unbroken egg, is a low entropy configuration,
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Nerazbijeno jaje ima malu entropiju,
14:33
and yet, when we open our refrigerator,
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ali kad otvorimo frižider
14:35
we do not go, "Hah, how surprising to find
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ne kažemo, "Kako iznenađujuće
14:37
this low entropy configuration in our refrigerator."
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konfiguracija niske entropije u mom frižideru."
14:39
That's because an egg is not a closed system;
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To je zato što jaje nije zatvoreni sustav;
14:42
it comes out of a chicken.
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ono dolazi od kokoši.
14:44
Maybe the universe comes out of a universal chicken.
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Možda svemir dolazi iz svemirske kokoši.
14:48
Maybe there is something that naturally,
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Možda nešto prirodno
14:50
through the growth of the laws of physics,
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kroz rast zakona fizike,
14:53
gives rise to universe like ours
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rađa svemir kao naš
14:55
in low entropy configurations.
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u konfiguracijama niske entropije.
14:57
If that's true, it would happen more than once;
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Ako je to istina, desilo se više puta;
14:59
we would be part of a much bigger multiverse.
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i mi smo dio većeg multisvemira.
15:02
That's my favorite scenario.
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To mi je najdraži scenarij.
15:04
So the organizers asked me to end with a bold speculation.
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Tražili su me da završim s odvažnom špekulacijom.
15:07
My bold speculation
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Ona je
15:09
is that I will be absolutely vindicated by history.
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da će me povijest opravdati.
15:12
And 50 years from now,
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Za 50 godina
15:14
all of my current wild ideas will be accepted as truths
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sve moje lude ideje će prihvatiti
15:17
by the scientific and external communities.
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znanstvene zajednice.
15:20
We will all believe that our little universe
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Svi ćemo vjerovati da je svemir
15:22
is just a small part of a much larger multiverse.
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dio većeg multisvemira.
15:25
And even better, we will understand what happened at the Big Bang
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Razumjet ćemo što se desilo kod Velikog Praska
15:28
in terms of a theory
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teorijom
15:30
that we will be able to compare to observations.
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koju ćemo moći ispitati.
15:32
This is a prediction. I might be wrong.
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To je predviđanje.
15:34
But we've been thinking as a human race
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Kao ljudska rasa smo razmišljali
15:36
about what the universe was like,
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kakav je svemir,
15:38
why it came to be in the way it did for many, many years.
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i zašto je ispao ovakav, puno godina.
15:41
It's exciting to think we may finally know the answer someday.
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Uzbudljivo je misliti da bi mogli naći odgovor.
15:44
Thank you.
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Hvala.
15:46
(Applause)
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(Pljesak)
ABOUT THE SPEAKER
Sean M. Carroll - Physicist, cosmologistA physicist, cosmologist and gifted science communicator, Sean Carroll is asking himself -- and asking us to consider -- questions that get at the fundamental nature of the universe.
Why you should listen
Sean Carroll is a theoretical physicist at Caltech in Pasadena, California, where he researches theoretical aspects of cosmology, field theory and gravitation -- exploring the nature of fundamental physics by studying the structure and evolution of the universe.
His book on cosmology and the arrow of time, From Eternity to Here: The Quest for the Ultimate Theory of Time, was published in 2010. He keeps a regular blog at Cosmic Variance.
Sean M. Carroll | Speaker | TED.com