TEDxCaltech
Sean Carroll: Distant time and the hint of a multiverse
Sean Carroll: Oddaljen čas in namig o mnogovesolju
Filmed:
Readability: 4.2
1,776,253 views
Kosmolog Sean Carroll nas na dogodku TEDxCaltech popelje na zabavno a obenem provokativno popotovanje skozi naravo časa in vesolja ob navidez preprostem vprašanju: zakaj čas sploh obstaja? Potencialni odgovor razkrije presenetljiv pogled na naravo vesolja in naše mesto v njem.
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
0
0
2000
Vesolje
00:17
is really big.
1
2000
2000
je res veliko.
00:19
We live in a galaxy, the Milky Way Galaxy.
2
4000
3000
Živimo v galaksiji, v Galaksiji Rimska cesta.
00:22
There are about a hundred billion stars in the Milky Way Galaxy.
3
7000
3000
Tu je približno sto milijard zvezd.
00:25
And if you take a camera
4
10000
2000
In če vzamemo kamero
00:27
and you point it at a random part of the sky,
5
12000
2000
in jo usmerimo v naključno točko na nebu,
00:29
and you just keep the shutter open,
6
14000
2000
in pustimo odprto zaslonko,
00:31
as long as your camera is attached to the Hubble Space Telescope,
7
16000
3000
seveda, če je naša kamera pripeta na vesoljski teleskop Hubble,
00:34
it will see something like this.
8
19000
2000
bomo videli nekaj takega.
00:36
Every one of these little blobs
9
21000
3000
In v vsaki teh lis
00:39
is a galaxy roughly the size of our Milky Way --
10
24000
2000
je galaksija približno velikosti naše Rimske ceste --
00:41
a hundred billion stars in each of those blobs.
11
26000
3000
sto milijard zvezd v vsaki taki lisi.
00:44
There are approximately a hundred billion galaxies
12
29000
3000
V vidnem vesolju je približno
00:47
in the observable universe.
13
32000
2000
sto milijard galaksij.
00:49
100 billion is the only number you need to know.
14
34000
2000
100 milijard je edino število, ki si ga moramo zapomniti.
00:51
The age of the universe, between now and the Big Bang,
15
36000
3000
Starost vesolja, med zdaj in Velikim Pokom
00:54
is a hundred billion in dog years.
16
39000
2000
je sto milijard v pasjih letih.
00:56
(Laughter)
17
41000
2000
(Smeh)
00:58
Which tells you something about our place in the universe.
18
43000
3000
Kar nam pove nekaj o našem mestu v vesolju.
01:01
One thing you can do with a picture like this is simply admire it.
19
46000
2000
Nekaj, kar naredimo s tako sliko, je preprosto občudovanje.
01:03
It's extremely beautiful.
20
48000
2000
To je izjemna lepota.
01:05
I've often wondered, what is the evolutionary pressure
21
50000
3000
Pogosto sem se spraševal, kakšen je pritisk evolucije
01:08
that made our ancestors in the Veldt adapt and evolve
22
53000
3000
ki je naše prednike izoblikoval do te mere
01:11
to really enjoy pictures of galaxies
23
56000
2000
da so uživali v slikah galaksij
01:13
when they didn't have any.
24
58000
2000
čeprav jih niso imeli.
01:15
But we would also like to understand it.
25
60000
2000
Toda mi bi jih radi tudi razumeli.
01:17
As a cosmologist, I want to ask, why is the universe like this?
26
62000
4000
Kot kosmolog, želim vprašati: Zakaj je vesolje takšno?
01:21
One big clue we have is that the universe is changing with time.
27
66000
3000
Velik namig, ki ga imamo, je da se vesolje spreminja skozi čas.
01:24
If you looked at one of these galaxies and measured its velocity,
28
69000
3000
Če bi gledali v eno teh galaksij in izmerili njeno hitrost,
01:27
it would be moving away from you.
29
72000
2000
bi se odmikala od nas.
01:29
And if you look at a galaxy even farther away,
30
74000
2000
In če se zazremo še v bolj oddaljeno galaksijo,
01:31
it would be moving away faster.
31
76000
2000
se le-ta odmika še hitreje.
01:33
So we say the universe is expanding.
32
78000
2000
Zato pravimo, da se vesolje širi.
01:35
What that means, of course, is that, in the past,
33
80000
2000
In to seveda pomeni, da so bile v preteklosti,
01:37
things were closer together.
34
82000
2000
vse stvari bližje skupaj.
01:39
In the past, the universe was more dense,
35
84000
2000
V preteklosti je bilo vesolje gostejše,
01:41
and it was also hotter.
36
86000
2000
in bilo je bolj vroče.
01:43
If you squeeze things together, the temperature goes up.
37
88000
2000
Če stisnemo stvari skupaj, temperatura naraste.
01:45
That kind of makes sense to us.
38
90000
2000
To se nam zdi smiselno.
01:47
The thing that doesn't make sense to us as much
39
92000
2000
Kar se nam ne zdi tako smiselno
01:49
is that the universe, at early times, near the Big Bang,
40
94000
3000
je, da je bilo vesolje, v zgodnji dobi, skoraj ob Velikem Poku,
01:52
was also very, very smooth.
41
97000
2000
tudi zelo gladko, enakomerno.
01:54
You might think that that's not a surprise.
42
99000
2000
Morda boste pomislili, da to ni presenetljivo.
01:56
The air in this room is very smooth.
43
101000
2000
Tudi zrak v tem prostoru je zelo enakomeren.
01:58
You might say, "Well, maybe things just smoothed themselves out."
44
103000
3000
Lahko rečete: "No, morda se stvari same uredijo".
02:01
But the conditions near the Big Bang are very, very different
45
106000
3000
Toda razmere ob Velikem Poku, so bile zelo, zelo drugačne
02:04
than the conditions of the air in this room.
46
109000
2000
kot so razmere zraka v tem prostoru.
02:06
In particular, things were a lot denser.
47
111000
2000
Še posebej, stvari so bile zelo gostejše.
02:08
The gravitational pull of things
48
113000
2000
Gravitacijske sile stvari
02:10
was a lot stronger near the Big Bang.
49
115000
2000
so bile močnejše ob Velikem Poku.
02:12
What you have to think about
50
117000
2000
Kar lahko razmislimo
02:14
is we have a universe with a hundred billion galaxies,
51
119000
2000
je, da imamo vesolje z sto milijardami galaksij
02:16
a hundred billion stars each.
52
121000
2000
in v vsaki sto milijard zvezd.
02:18
At early times, those hundred billion galaxies
53
123000
3000
V zgodnjih časih, so bile te milijarde galaksij
02:21
were squeezed into a region about this big --
54
126000
3000
stisnjene v območje približno te velikosti --
02:24
literally -- at early times.
55
129000
2000
dobesedno, v zgodnjih časih.
02:26
And you have to imagine doing that squeezing
56
131000
2000
In predstavljajte si tako stiskanje
02:28
without any imperfections,
57
133000
2000
brez kakršnih koli nepopolnosti,
02:30
without any little spots
58
135000
2000
brez nobenih malih točk
02:32
where there were a few more atoms than somewhere else.
59
137000
2000
kjer bi bilo nekaj manj atomov, kot nekje drugje.
02:34
Because if there had been, they would have collapsed under the gravitational pull
60
139000
3000
Kajti, če bi bile, bi se zrušile pod gravitacijsko silo
02:37
into a huge black hole.
61
142000
2000
v ogromno črno luknjo.
02:39
Keeping the universe very, very smooth at early times
62
144000
3000
Ohranjanje zelo enakomernega vesolja v zgodnjih časih
02:42
is not easy; it's a delicate arrangement.
63
147000
2000
ni preprosto, je občutljiva ureditev.
02:44
It's a clue
64
149000
2000
To je namig,
02:46
that the early universe is not chosen randomly.
65
151000
2000
da zgodnje vesolje ni izbrano naključno.
02:48
There is something that made it that way.
66
153000
2000
Tu je nekaj, kar ga je ustvarilo na ta način.
02:50
We would like to know what.
67
155000
2000
In mi bi radi vedeli kaj.
02:52
So part of our understanding of this was given to us by Ludwig Boltzmann,
68
157000
3000
Torej del našega razumevanja nam je podal Ludwig Boltzmann,
02:55
an Austrian physicist in the 19th century.
69
160000
3000
austrijski fizik v 19. stoletju.
02:58
And Boltzmann's contribution was that he helped us understand entropy.
70
163000
3000
In Boltzmannov prispevek nam je pomagal razumeti entropijo.
03:01
You've heard of entropy.
71
166000
2000
Slišali ste za entropijo.
03:03
It's the randomness, the disorder, the chaoticness of some systems.
72
168000
3000
To je naključje, nered, kaotičnost nekih sistemov.
03:06
Boltzmann gave us a formula --
73
171000
2000
Boltzmann nam je podal formulo --
03:08
engraved on his tombstone now --
74
173000
2000
danes vklesano na njegov nagrobnik --
03:10
that really quantifies what entropy is.
75
175000
2000
ki količinsko določa kaj je entropija.
03:12
And it's basically just saying
76
177000
2000
In v bistvu pravi le,
03:14
that entropy is the number of ways
77
179000
2000
da je entropija število načinov,
03:16
we can rearrange the constituents of a system so that you don't notice,
78
181000
3000
s katerimi lahko prerazporedimo sestavine sistema, tako da se ne opazi,
03:19
so that macroscopically it looks the same.
79
184000
2000
tako, da makroskopsko zgleda enako.
03:21
If you have the air in this room,
80
186000
2000
Če vzamemo zrak v tej sobi,
03:23
you don't notice each individual atom.
81
188000
3000
ne opazimo vsakega posameznega atoma.
03:26
A low entropy configuration
82
191000
2000
Nizka konfiguracija entropije
03:28
is one in which there's only a few arrangements that look that way.
83
193000
2000
je taka, v kateri je samo nekaj postavitev, ki zgledajo tako.
03:30
A high entropy arrangement
84
195000
2000
Visoka ureditev entropije
03:32
is one that there are many arrangements that look that way.
85
197000
2000
je taka, kjer je več možnih postavitev, ki zgledajo tako.
03:34
This is a crucially important insight
86
199000
2000
To je ključnega pomena,
03:36
because it helps us explain
87
201000
2000
ker nam pomaga razložiti
03:38
the second law of thermodynamics --
88
203000
2000
drugi zakon termodinamike --
03:40
the law that says that entropy increases in the universe,
89
205000
3000
zakon, ki pravi, da entropija v vesolju narašča.
03:43
or in some isolated bit of the universe.
90
208000
2000
ali v omejenem delčku vesolja.
03:45
The reason why entropy increases
91
210000
2000
Razlog za naraščanje entropije
03:47
is simply because there are many more ways
92
212000
3000
je preprost, ker je veliko več načinov
03:50
to be high entropy than to be low entropy.
93
215000
2000
za doseganje visoke entropije, kot nizke entropije.
03:52
That's a wonderful insight,
94
217000
2000
To je čudovito razumevanje,
03:54
but it leaves something out.
95
219000
2000
vendar nekaj manjka.
03:56
This insight that entropy increases, by the way,
96
221000
2000
Razumevanje, da entropija narašča, mimogrede,
03:58
is what's behind what we call the arrow of time,
97
223000
3000
kar je za nami imenujemo časovni vektor,
04:01
the difference between the past and the future.
98
226000
2000
razlika med preteklostjo in prihodnjostjo.
04:03
Every difference that there is
99
228000
2000
Vsaka razlika
04:05
between the past and the future
100
230000
2000
med preteklostjo in prihodnjostjo
04:07
is because entropy is increasing --
101
232000
2000
je zaradi naraščanja entropije --
04:09
the fact that you can remember the past, but not the future.
102
234000
3000
dejstvo, da se lahko spomnimo preteklosti, toda ne prihodnosti.
04:12
The fact that you are born, and then you live, and then you die,
103
237000
3000
Dejstvo, da se rodimo, živimo in umremo,
04:15
always in that order,
104
240000
2000
vedno v tem vrstnem redu,
04:17
that's because entropy is increasing.
105
242000
2000
to je zaradi naraščanja entropije.
04:19
Boltzmann explained that if you start with low entropy,
106
244000
2000
Boltzmann je razložil tudi, da če začnemo z nizko entropijo,
04:21
it's very natural for it to increase
107
246000
2000
je zelo naravno, da se poveča,
04:23
because there's more ways to be high entropy.
108
248000
3000
ker je veliko več načinov za stanja z visoko entropijo.
04:26
What he didn't explain
109
251000
2000
Kar pa ni razložil,
04:28
was why the entropy was ever low in the first place.
110
253000
3000
je zakaj je bila entropija vedno nizka v izhodišču.
04:31
The fact that the entropy of the universe was low
111
256000
2000
Dejstvo, da je bila entropija vesolja nizka
04:33
was a reflection of the fact
112
258000
2000
je odsev dejstva
04:35
that the early universe was very, very smooth.
113
260000
2000
da je bilo prvotno vesolje zelo enakomerno.
04:37
We'd like to understand that.
114
262000
2000
To bi radi razumeli.
04:39
That's our job as cosmologists.
115
264000
2000
To je naloga nas kozmologov.
04:41
Unfortunately, it's actually not a problem
116
266000
2000
Nažalost, to ni problem,
04:43
that we've been giving enough attention to.
117
268000
2000
ki smo mu namenili dovolj pozornosti.
04:45
It's not one of the first things people would say,
118
270000
2000
To ni en izmed prvih odgovorov, ki ga slišiš,
04:47
if you asked a modern cosmologist,
119
272000
2000
če vprašaš sodobnega kozmologa:
04:49
"What are the problems we're trying to address?"
120
274000
2000
"Katere probleme poskušate rešiti?"
04:51
One of the people who did understand that this was a problem
121
276000
2000
Nekdo, ki je razumel, da je to problem
04:53
was Richard Feynman.
122
278000
2000
je bil Richard Feynman.
04:55
50 years ago, he gave a series of a bunch of different lectures.
123
280000
2000
Pred 50 leti, je imel serijo rezličnih predavanj.
04:57
He gave the popular lectures
124
282000
2000
Predaval je na priljubljenih predavanjih
04:59
that became "The Character of Physical Law."
125
284000
2000
ki so postali "Karakter fizikalnih zakonov".
05:01
He gave lectures to Caltech undergrads
126
286000
2000
Predaval je študentom na Caltechu,
05:03
that became "The Feynman Lectures on Physics."
127
288000
2000
danes znanimi kot "Feynmanova predavanja o fiziki".
05:05
He gave lectures to Caltech graduate students
128
290000
2000
Predaval je Caltech-ovim podiplomantom,
05:07
that became "The Feynman Lectures on Gravitation."
129
292000
2000
kar poznamo kot "Feynmanova predavanja o gravitaciji".
05:09
In every one of these books, every one of these sets of lectures,
130
294000
3000
V vsaki izmed teh knjig, vsaki zbirki predavanj,
05:12
he emphasized this puzzle:
131
297000
2000
je povdarjal vprašanje:
05:14
Why did the early universe have such a small entropy?
132
299000
3000
Zakaj je imelo zgodnje vesolje tako majhno entropijo?
05:17
So he says -- I'm not going to do the accent --
133
302000
2000
Tako pravi -- In ne bom naglaševal --
05:19
he says, "For some reason, the universe, at one time,
134
304000
3000
pravi: "Zaradi nekega vzroka, je vesolje, v nekem času,
05:22
had a very low entropy for its energy content,
135
307000
3000
imelo zelo nizko entropijo za svojo energijsko vsebnost,
05:25
and since then the entropy has increased.
136
310000
2000
in odtlej je entropija naraščala.
05:27
The arrow of time cannot be completely understood
137
312000
3000
Časovnega vektorja ne moremo povsem razumeti
05:30
until the mystery of the beginnings of the history of the universe
138
315000
3000
dokler skrivnost začetka zgodovine vesolja
05:33
are reduced still further
139
318000
2000
ni dokončno zmanjšana
05:35
from speculation to understanding."
140
320000
2000
iz špekulacije v razumevanje".
05:37
So that's our job.
141
322000
2000
To je naša naloga.
05:39
We want to know -- this is 50 years ago, "Surely," you're thinking,
142
324000
2000
Želimo vedeti -- to je bilo pred 50 leti in razmišljate: "Seveda
05:41
"we've figured it out by now."
143
326000
2000
do danes smo to rezrešili".
05:43
It's not true that we've figured it out by now.
144
328000
2000
Ni res, da smo do danes to rezrešili.
05:45
The reason the problem has gotten worse,
145
330000
2000
Problem je postal še večji
05:47
rather than better,
146
332000
2000
namesto lažji,
05:49
is because in 1998
147
334000
2000
ker smo v letu 1998
05:51
we learned something crucial about the universe that we didn't know before.
148
336000
3000
spoznali nekaj ključnega o vesolju, česar doslej nismo vedeli.
05:54
We learned that it's accelerating.
149
339000
2000
Spoznali smo, da vesolje pospešuje.
05:56
The universe is not only expanding.
150
341000
2000
Vesolje se ne samo širi.
05:58
If you look at the galaxy, it's moving away.
151
343000
2000
Če pogledate galaksije, se oddaljujejo.
06:00
If you come back a billion years later and look at it again,
152
345000
2000
Če se vrnemo čez milijard let in spet pogledamo,
06:02
it will be moving away faster.
153
347000
3000
se galaksije oddaljujejo še hitreje.
06:05
Individual galaxies are speeding away from us faster and faster
154
350000
3000
Posamezne galaksije drvijo stran od nas hitreje in hitreje.
06:08
so we say the universe is accelerating.
155
353000
2000
Tako pravimo, da vesolje pospešuje.
06:10
Unlike the low entropy of the early universe,
156
355000
2000
Za razliko od nizke entropije zgodnjega vesolja,
06:12
even though we don't know the answer for this,
157
357000
2000
čeprav ne poznamo odgovora na to,
06:14
we at least have a good theory that can explain it,
158
359000
2000
imamo vsaj dobro terorijo, ki nam to lahko razloži,
06:16
if that theory is right,
159
361000
2000
in če je teorija pravilna,
06:18
and that's the theory of dark energy.
160
363000
2000
je to teorija temne energije.
06:20
It's just the idea that empty space itself has energy.
161
365000
3000
Je le ideja, da ima tudi prazen prostor energijo.
06:23
In every little cubic centimeter of space,
162
368000
3000
V vsakem malem kubičnem centimetru prostora,
06:26
whether or not there's stuff,
163
371000
2000
neglede na to kaj vsebuje,
06:28
whether or not there's particles, matter, radiation or whatever,
164
373000
2000
neglede ali so ali ni delcev, materije, sevanja ali česarkoli,
06:30
there's still energy, even in the space itself.
165
375000
3000
še vedno je prisotna energija v samem prostoru.
06:33
And this energy, according to Einstein,
166
378000
2000
In ta energija, po Einsteinu
06:35
exerts a push on the universe.
167
380000
3000
izvaja potisk na vesolje.
06:38
It is a perpetual impulse
168
383000
2000
To je ponavljajoč impulz,
06:40
that pushes galaxies apart from each other.
169
385000
2000
ki potiska galaksije narazen eno od druge.
06:42
Because dark energy, unlike matter or radiation,
170
387000
3000
Ker se temna energija, za razliko od snovi ali sevanja,
06:45
does not dilute away as the universe expands.
171
390000
3000
ne razredči medtem, ko se vesolje širi.
06:48
The amount of energy in each cubic centimeter
172
393000
2000
Količina energije v vsakem kubičnem centimetru
06:50
remains the same,
173
395000
2000
ostaja enaka,
06:52
even as the universe gets bigger and bigger.
174
397000
2000
tudi, ko se vesolje veča in veča.
06:54
This has crucial implications
175
399000
3000
To ima ključne posledice
06:57
for what the universe is going to do in the future.
176
402000
3000
na obnašanje vesolja v prihodnjosti.
07:00
For one thing, the universe will expand forever.
177
405000
2000
Ena stvar: vesolje se bo večno širilo.
07:02
Back when I was your age,
178
407000
2000
Ko sem bil vaše starosti,
07:04
we didn't know what the universe was going to do.
179
409000
2000
nismo vedeli, kaj se bo zgodilo z vesoljem.
07:06
Some people thought that the universe would recollapse in the future.
180
411000
3000
Nekateri so mislili, da se bo vesolje v prihodnosti sesedlo.
07:09
Einstein was fond of this idea.
181
414000
2000
Einsteinu je bila ta ideja všeč.
07:11
But if there's dark energy, and the dark energy does not go away,
182
416000
3000
Toda če je temna energija, in če temna energija ne gre stran,
07:14
the universe is just going to keep expanding forever and ever and ever.
183
419000
3000
se bo vesolje le širilo in širilo za vse večne čase.
07:17
14 billion years in the past,
184
422000
2000
14 milijard let nazaj,
07:19
100 billion dog years,
185
424000
2000
100 milijard pasjih let,
07:21
but an infinite number of years into the future.
186
426000
3000
toda neskončno število let v prihodnjost.
07:24
Meanwhile, for all intents and purposes,
187
429000
3000
Medtem, za vse namene in namere,
07:27
space looks finite to us.
188
432000
2000
prostor vidimo kot končen.
07:29
Space may be finite or infinite,
189
434000
2000
Prostor je lahko končen ali neskončen,
07:31
but because the universe is accelerating,
190
436000
2000
vendar, ker vesolje pospešuje,
07:33
there are parts of it we cannot see
191
438000
2000
so predeli, ki jih ne moremo videti
07:35
and never will see.
192
440000
2000
in jih nikoli ne bomo videli.
07:37
There's a finite region of space that we have access to,
193
442000
2000
Imamo dostop le do končnega območja vesolja,
07:39
surrounded by a horizon.
194
444000
2000
ki ga obkroža obzorje.
07:41
So even though time goes on forever,
195
446000
2000
Tudi če je čas neskončen,
07:43
space is limited to us.
196
448000
2000
je prostor za nas omejen.
07:45
Finally, empty space has a temperature.
197
450000
3000
Končno, prazen prostor ima temperaturo.
07:48
In the 1970s, Stephen Hawking told us
198
453000
2000
1970 nam je Stephen Hawking povedal,
07:50
that a black hole, even though you think it's black,
199
455000
2000
da črna luknja, čeprav mislimo, da je črna,
07:52
it actually emits radiation
200
457000
2000
pravzaprav oddaja sevanje,
07:54
when you take into account quantum mechanics.
201
459000
2000
če upoštevamo kvantno mehaniko.
07:56
The curvature of space-time around the black hole
202
461000
3000
Ukrivljenost prostora-časa okrog črne luknje
07:59
brings to life the quantum mechanical fluctuation,
203
464000
3000
oživi kvantno mehanično fluktuacijo,
08:02
and the black hole radiates.
204
467000
2000
in tako črna luknja seva.
08:04
A precisely similar calculation by Hawking and Gary Gibbons
205
469000
3000
Natančno podoben izračun Hawkinga and Gary Gibbonsa
08:07
showed that if you have dark energy in empty space,
206
472000
3000
je pokazal, da če imamo temno energijo v praznem prostoru,
08:10
then the whole universe radiates.
207
475000
3000
potem celotno vesolje seva.
08:13
The energy of empty space
208
478000
2000
Energija praznega prostora
08:15
brings to life quantum fluctuations.
209
480000
2000
oživi kvantno fluktuacijo.
08:17
And so even though the universe will last forever,
210
482000
2000
Tudi če bo vesolje trajalo večno,
08:19
and ordinary matter and radiation will dilute away,
211
484000
3000
in se bo običajna snov in sevanje redčilo,
08:22
there will always be some radiation,
212
487000
2000
bo vedno ostalo nekaj sevanja,
08:24
some thermal fluctuations,
213
489000
2000
nekaj termične fluktuacije,
08:26
even in empty space.
214
491000
2000
tudi v praznem prostoru.
08:28
So what this means
215
493000
2000
To pomeni,
08:30
is that the universe is like a box of gas
216
495000
2000
da je vesolje kot škatla plina,
08:32
that lasts forever.
217
497000
2000
ki traja večno.
08:34
Well what is the implication of that?
218
499000
2000
In kaj je posledica tega?
08:36
That implication was studied by Boltzmann back in the 19th century.
219
501000
3000
Posledice je proučeval Boltzmann v 19. stoletju.
08:39
He said, well, entropy increases
220
504000
3000
Rekel je, no, entropija narašča
08:42
because there are many, many more ways
221
507000
2000
ker obstaja veliko, veliko več načinov,
08:44
for the universe to be high entropy, rather than low entropy.
222
509000
3000
da je vesolje z visoko entropijo, kot z nizko entropijo.
08:47
But that's a probabilistic statement.
223
512000
3000
Toda to je verjetnostna izjava.
08:50
It will probably increase,
224
515000
2000
Verjetno bo naraščala,
08:52
and the probability is enormously huge.
225
517000
2000
in ta verjetnost je ogromna.
08:54
It's not something you have to worry about --
226
519000
2000
Zagotovo nam ni treba skrbeti,
08:56
the air in this room all gathering over one part of the room and suffocating us.
227
521000
4000
da se ves zrak v tej sobi zbere v eni sami točki in nas tako zaduši.
09:00
It's very, very unlikely.
228
525000
2000
To je zelo, zelo neverjetno.
09:02
Except if they locked the doors
229
527000
2000
Razen, če bi kdo zaklenil vrata
09:04
and kept us here literally forever,
230
529000
2000
in nas zadrževal tu dobesedno za vedno,
09:06
that would happen.
231
531000
2000
bi se to zgodilo.
09:08
Everything that is allowed,
232
533000
2000
Vse kar je dovoljeno,
09:10
every configuration that is allowed to be obtained by the molecules in this room,
233
535000
3000
vsaka postavitev, ki se lahko pripeti molekulam v tej sobi,
09:13
would eventually be obtained.
234
538000
2000
je lahko dosežena pod pravimi pogoji.
09:15
So Boltzmann says, look, you could start with a universe
235
540000
3000
Boltzmann pravi: poglej, lahko začnemo vesolje
09:18
that was in thermal equilibrium.
236
543000
2000
ki je v termičnem ravnovesju.
09:20
He didn't know about the Big Bang. He didn't know about the expansion of the universe.
237
545000
3000
Ni vedel za Veliki Pok. Ni vedel za širjenje vesolja.
09:23
He thought that space and time were explained by Isaac Newton --
238
548000
3000
Mislil je, da sta prostor in čas razložena po Isaacu Newtonu --
09:26
they were absolute; they just stuck there forever.
239
551000
2000
bila sta absolutna in večna.
09:28
So his idea of a natural universe
240
553000
2000
Njegova ideja naravnega vesolja
09:30
was one in which the air molecules were just spread out evenly everywhere --
241
555000
3000
je bila taka, kjer se molekule zraka širijo vsepovsod enakomerno --
09:33
the everything molecules.
242
558000
2000
vse molekule.
09:35
But if you're Boltzmann, you know that if you wait long enough,
243
560000
3000
Toda če ste vi Boltzmann, veste, da če čakaš dovolj časa,
09:38
the random fluctuations of those molecules
244
563000
3000
naključna fluktuacija teh molekul
09:41
will occasionally bring them
245
566000
2000
občasno pripelje molekule
09:43
into lower entropy configurations.
246
568000
2000
v konfiguracije nizke entropije.
09:45
And then, of course, in the natural course of things,
247
570000
2000
In tedaj, seveda, se v naravnem toku,
09:47
they will expand back.
248
572000
2000
ponovno razširijo.
09:49
So it's not that entropy must always increase --
249
574000
2000
Torej ni nujno, da entropija vedno narašča --
09:51
you can get fluctuations into lower entropy,
250
576000
3000
lahko dobimo fluktuacije v nižjo entropijo,
09:54
more organized situations.
251
579000
2000
bolj urejene razmere.
09:56
Well if that's true,
252
581000
2000
Če je to res,
09:58
Boltzmann then goes onto invent
253
583000
2000
Boltzmann izumlja
10:00
two very modern-sounding ideas --
254
585000
2000
dve zelo sodobni ideji --
10:02
the multiverse and the anthropic principle.
255
587000
3000
mnogovesolje in antropično načelo.
10:05
He says, the problem with thermal equilibrium
256
590000
2000
Govori nam, da je problem s termičnim ravnovesjem,
10:07
is that we can't live there.
257
592000
2000
da ne moremo živeti tam.
10:09
Remember, life itself depends on the arrow of time.
258
594000
3000
Pomnite, življenje samo je odvisno od časovnega vektorja.
10:12
We would not be able to process information,
259
597000
2000
Nebi mogli obdelovati informacij,
10:14
metabolize, walk and talk,
260
599000
2000
prebavljati, hoditi in govoriti,
10:16
if we lived in thermal equilibrium.
261
601000
2000
če bi živeli v termičnem ravnovesju.
10:18
So if you imagine a very, very big universe,
262
603000
2000
Tako, če si predstavljate veliko, zelo veliko vesolje,
10:20
an infinitely big universe,
263
605000
2000
neskončno veliko vesolje,
10:22
with randomly bumping into each other particles,
264
607000
2000
z delci, ki se naključno zaletajo eden v drugega,
10:24
there will occasionally be small fluctuations in the lower entropy states,
265
609000
3000
bo prišlo do občasnih majhnih nihanj v nizkem stanju entropije,
10:27
and then they relax back.
266
612000
2000
ki se nato zopet sprostijo.
10:29
But there will also be large fluctuations.
267
614000
2000
Toda prihajalo bo tudi do večjih nihanj.
10:31
Occasionally, you will make a planet
268
616000
2000
Občasno, bo ustvarjen planet
10:33
or a star or a galaxy
269
618000
2000
ali zvezda ali galaksija
10:35
or a hundred billion galaxies.
270
620000
2000
ali sto milijard galaksij.
10:37
So Boltzmann says,
271
622000
2000
Torej Boltzmann govori,
10:39
we will only live in the part of the multiverse,
272
624000
3000
da bomo živeli samo v delu mnogovesolja,
10:42
in the part of this infinitely big set of fluctuating particles,
273
627000
3000
v delu tega neskončnega nabora nihajočih delcev,
10:45
where life is possible.
274
630000
2000
kjer je možno življenje.
10:47
That's the region where entropy is low.
275
632000
2000
To je področje, kjer je entropija nizka.
10:49
Maybe our universe is just one of those things
276
634000
3000
Morda je naše vesolje le ena izmed stvari,
10:52
that happens from time to time.
277
637000
2000
ki se zgodijo občasno.
10:54
Now your homework assignment
278
639000
2000
Zdaj je vaša domača naloga,
10:56
is to really think about this, to contemplate what it means.
279
641000
2000
da razmišljate o tem, kaj to pomeni.
10:58
Carl Sagan once famously said
280
643000
2000
Carl Sagan je nekoč izjavil,
11:00
that "in order to make an apple pie,
281
645000
2000
da "če želimo speči jabolčno pito,
11:02
you must first invent the universe."
282
647000
3000
moramo najprej izumiti vesolje".
11:05
But he was not right.
283
650000
2000
Toda ni imel prav.
11:07
In Boltzmann's scenario, if you want to make an apple pie,
284
652000
3000
Po Boltzmannu, če želimo speči jabolčno pito,
11:10
you just wait for the random motion of atoms
285
655000
3000
le počakamo na naključno gibanje atomov,
11:13
to make you an apple pie.
286
658000
2000
ki nam speče pito.
11:15
That will happen much more frequently
287
660000
2000
To se bo dogajalo bolj pogosto
11:17
than the random motions of atoms
288
662000
2000
kot naključno gibanje atomov,
11:19
making you an apple orchard
289
664000
2000
ki pripelje do sadovnjaka
11:21
and some sugar and an oven,
290
666000
2000
in nekaj sladkorja in pečice,
11:23
and then making you an apple pie.
291
668000
2000
in nam nato speče pito.
11:25
So this scenario makes predictions.
292
670000
3000
Ta scenarij daje napovedi.
11:28
And the predictions are
293
673000
2000
In napovedi so,
11:30
that the fluctuations that make us are minimal.
294
675000
3000
da so nihanja, ki nas ustvarjajo minimalna.
11:33
Even if you imagine that this room we are in now
295
678000
3000
Tudi, če si predstavljate, da ta soba
11:36
exists and is real and here we are,
296
681000
2000
obstaja in je resnična, da smo tukaj,
11:38
and we have, not only our memories,
297
683000
2000
imamo svoje spomine in
11:40
but our impression that outside there's something
298
685000
2000
vtis, da je tam zunaj nekaj
11:42
called Caltech and the United States and the Milky Way Galaxy,
299
687000
4000
imenovanega Caltech in ZDA in galaksija Rimska cesta,
11:46
it's much easier for all those impressions to randomly fluctuate into your brain
300
691000
3000
je enostavnejše, da se vsi ti vtisi naključno zanihajo v vaših možganih,
11:49
than for them actually to randomly fluctuate
301
694000
2000
kot za pravo naključno nihanje
11:51
into Caltech, the United States and the galaxy.
302
696000
3000
v Caltech, ZDA in galaksijo.
11:54
The good news is that,
303
699000
2000
Dobra stvar je,
11:56
therefore, this scenario does not work; it is not right.
304
701000
3000
da ta scenarij ne deluje, ni pravi.
11:59
This scenario predicts that we should be a minimal fluctuation.
305
704000
3000
Ta scenarij predvideva, da smo minimalno nihanje.
12:02
Even if you left our galaxy out,
306
707000
2000
Tudi če izpustimo našo galaksijo,
12:04
you would not get a hundred billion other galaxies.
307
709000
2000
ne bi dobili sto milijard drugih galaksij.
12:06
And Feynman also understood this.
308
711000
2000
In tudi Feynman je razumel to.
12:08
Feynman says, "From the hypothesis that the world is a fluctuation,
309
713000
4000
Feynman govori: "Od hipoteze da je svet nihanje,
12:12
all the predictions are that
310
717000
2000
in vse napoveduje,
12:14
if we look at a part of the world we've never seen before,
311
719000
2000
da če pogledamo del sveta, ki ga še nismo doslej,
12:16
we will find it mixed up, and not like the piece we've just looked at --
312
721000
2000
bo ta zmešan, nič kot predel, ki smo ga gledali --
12:18
high entropy.
313
723000
2000
visoka entropija.
12:20
If our order were due to a fluctuation,
314
725000
2000
Če je naš red zaradi nihanja,
12:22
we would not expect order anywhere but where we have just noticed it.
315
727000
2000
nebi pričakovali reda nikjer drugje razen, kjer smo ga pravkar zaznali.
12:24
We therefore conclude the universe is not a fluctuation."
316
729000
4000
Zatorej zaključujemo, da vesolje ni nihanje".
12:28
So that's good. The question is then what is the right answer?
317
733000
3000
To je dobro. Vprašanje je kaj je pravi odgovor?
12:31
If the universe is not a fluctuation,
318
736000
2000
Če vesolje ni nihanje,
12:33
why did the early universe have a low entropy?
319
738000
3000
zakaj je zgodnje vesolje imelo nizko entropijo?
12:36
And I would love to tell you the answer, but I'm running out of time.
320
741000
3000
In rad bi vam povedal odgovor, a moj čas se izteka.
12:39
(Laughter)
321
744000
2000
(Smeh)
12:41
Here is the universe that we tell you about,
322
746000
2000
Tu je vesolje o katerem govorimo,
12:43
versus the universe that really exists.
323
748000
2000
nasproti vesolji, ki zares obstaja.
12:45
I just showed you this picture.
324
750000
2000
Pravkar sem vam pokazal to sliko.
12:47
The universe is expanding for the last 10 billion years or so.
325
752000
2000
Vesolje se širi že vsaj zadnjih 10 milijard let.
12:49
It's cooling off.
326
754000
2000
Ohlaja se.
12:51
But we now know enough about the future of the universe
327
756000
2000
Toda zdaj vemo dovolj o prihodnosti vesolja,
12:53
to say a lot more.
328
758000
2000
da rečemo veliko več.
12:55
If the dark energy remains around,
329
760000
2000
Če temna energija ostaja okrog,
12:57
the stars around us will use up their nuclear fuel, they will stop burning.
330
762000
3000
bodo zvezde okrog nas porabile svojo jedrsko gorivo in ugasnile.
13:00
They will fall into black holes.
331
765000
2000
Padle bodo v črne luknje.
13:02
We will live in a universe
332
767000
2000
Živeli bomo v vesolju
13:04
with nothing in it but black holes.
333
769000
2000
brez ničesar v njem, razen črnih lukenj.
13:06
That universe will last 10 to the 100 years --
334
771000
4000
To vesolje bo trajalo 10 do 100 let --
13:10
a lot longer than our little universe has lived.
335
775000
2000
veliko dlje, kot je živelo naše malo vesolje.
13:12
The future is much longer than the past.
336
777000
2000
Prihodnost je veliko daljša od preteklosti.
13:14
But even black holes don't last forever.
337
779000
2000
Tudi če črne luknje ne trajajo večno.
13:16
They will evaporate,
338
781000
2000
Bodo izhlapele,
13:18
and we will be left with nothing but empty space.
339
783000
2000
in ostal nam bo le prazen prostor.
13:20
That empty space lasts essentially forever.
340
785000
4000
Tak prazen prostor v bistvu traja večno.
13:24
However, you notice, since empty space gives off radiation,
341
789000
3000
Kakorkoli, če opazite, ker prazen prostor oddaja sevanje,
13:27
there's actually thermal fluctuations,
342
792000
2000
so tam pravzaprav termična nihanja,
13:29
and it cycles around
343
794000
2000
in ciklično prehajajo
13:31
all the different possible combinations
344
796000
2000
vse različne možne kombinacije
13:33
of the degrees of freedom that exist in empty space.
345
798000
3000
stopenj svobode, ki obstajajo v praznem prostoru.
13:36
So even though the universe lasts forever,
346
801000
2000
Tako tudi, če je vesolje večno,
13:38
there's only a finite number of things
347
803000
2000
je le končno mnogo stvari,
13:40
that can possibly happen in the universe.
348
805000
2000
ki se lahko zgodijo v vesolju.
13:42
They all happen over a period of time
349
807000
2000
Vse se zgodijo v časovnem obdobju
13:44
equal to 10 to the 10 to the 120 years.
350
809000
3000
enakem 10 na 10 na 120 let.
13:47
So here's two questions for you.
351
812000
2000
Tu sta dve vprašanji za vas.
13:49
Number one: If the universe lasts for 10 to the 10 to the 120 years,
352
814000
3000
Prvo: Če vesolje traja 10 na 10 na 120 let,
13:52
why are we born
353
817000
2000
zakaj se rodimo
13:54
in the first 14 billion years of it,
354
819000
3000
v prvih 14 milijard let vesolja,
13:57
in the warm, comfortable afterglow of the Big Bang?
355
822000
3000
v toplem, udobnem siju Velikega Poka?
14:00
Why aren't we in empty space?
356
825000
2000
Zakaj nismo v praznem prostoru?
14:02
You might say, "Well there's nothing there to be living,"
357
827000
2000
Lahko rečete: "No, tam ni ničesar za življenje".
14:04
but that's not right.
358
829000
2000
Toda to ni pravilno.
14:06
You could be a random fluctuation out of the nothingness.
359
831000
2000
Lahko bi bili naključno nihanje iz ničesar.
14:08
Why aren't you?
360
833000
2000
Zakaj niste?
14:10
More homework assignment for you.
361
835000
3000
Še nekaj domačih nalog za vas.
14:13
So like I said, I don't actually know the answer.
362
838000
2000
Kot sem rekel, pravzaprav ne vem odgovora.
14:15
I'm going to give you my favorite scenario.
363
840000
2000
Podal vam bom moj najljubši scenarij.
14:17
Either it's just like that. There is no explanation.
364
842000
3000
Bodisi da je tako. Ni razlage.
14:20
This is a brute fact about the universe
365
845000
2000
To je surovo dejstvo o vesolju,
14:22
that you should learn to accept and stop asking questions.
366
847000
3000
ki ga morate spoznati in sprejeti ter nehati postavljati vprašanja.
14:26
Or maybe the Big Bang
367
851000
2000
Ali morda Veliki Pok
14:28
is not the beginning of the universe.
368
853000
2000
ni začetek vesolja.
14:30
An egg, an unbroken egg, is a low entropy configuration,
369
855000
3000
Jajce, ne-razbito jajce, je konfiguracija z nizko entropijo,
14:33
and yet, when we open our refrigerator,
370
858000
2000
in ko odpremo hladilnik
14:35
we do not go, "Hah, how surprising to find
371
860000
2000
ne rečemo, "Ha, kako presenetljivo najti
14:37
this low entropy configuration in our refrigerator."
372
862000
2000
to nizko stopnjo entropije v našem hladilniku".
14:39
That's because an egg is not a closed system;
373
864000
3000
To je ker jajce ni zaprt sistem;
14:42
it comes out of a chicken.
374
867000
2000
pride iz kokoši.
14:44
Maybe the universe comes out of a universal chicken.
375
869000
4000
Morda vesolje pride iz vesoljne kokoši.
14:48
Maybe there is something that naturally,
376
873000
2000
Morda je tam nekaj, kar naravno
14:50
through the growth of the laws of physics,
377
875000
3000
skozi razvoj zakonov fizike,
14:53
gives rise to universe like ours
378
878000
2000
daje porast vesolju, kot je naše
14:55
in low entropy configurations.
379
880000
2000
z nizko entropijo.
14:57
If that's true, it would happen more than once;
380
882000
2000
Če je to res, bi se zgodilo več kot enkrat;
14:59
we would be part of a much bigger multiverse.
381
884000
3000
bi bili del veliko večjega mnogovesolja.
15:02
That's my favorite scenario.
382
887000
2000
To je moj najljubši scenarij.
15:04
So the organizers asked me to end with a bold speculation.
383
889000
3000
Organizatorji so me prosili naj zaključim z drzno špekulacijo.
15:07
My bold speculation
384
892000
2000
Moja drzna špekulacija
15:09
is that I will be absolutely vindicated by history.
385
894000
3000
je da me bo zgodovina popolnoma upravičila.
15:12
And 50 years from now,
386
897000
2000
In čez 50 let,
15:14
all of my current wild ideas will be accepted as truths
387
899000
3000
bodo vse moje trenutno divje ideje sprejete kot resnične
15:17
by the scientific and external communities.
388
902000
3000
tako znanstveniki kot druge skupnosti.
15:20
We will all believe that our little universe
389
905000
2000
Vsi bomo verjeli, da je naše malo vesolje
15:22
is just a small part of a much larger multiverse.
390
907000
3000
le majhen delček veliko večjega mnogovesolja.
15:25
And even better, we will understand what happened at the Big Bang
391
910000
3000
In še več, razumeli bomo kaj se je zgodilo ob Velikem Poku
15:28
in terms of a theory
392
913000
2000
v teoretičnem smislu,
15:30
that we will be able to compare to observations.
393
915000
2000
ker bomo lahko primerjali opazovanja.
15:32
This is a prediction. I might be wrong.
394
917000
2000
To je moja napoved. Lahko se motim.
15:34
But we've been thinking as a human race
395
919000
2000
Toda kot človeštvo razmišljamo
15:36
about what the universe was like,
396
921000
2000
o tem, kakšno je bilo vesolje in
15:38
why it came to be in the way it did for many, many years.
397
923000
3000
zakaj je nastalo in je takšno kot je, že mnogo, mnogo let.
15:41
It's exciting to think we may finally know the answer someday.
398
926000
3000
Razburljivo je, če pomislimo, da bomo morda nekoč le vedeli odgovor.
15:44
Thank you.
399
929000
2000
Hvala vam.
15:46
(Applause)
400
931000
2000
(Aplavz)
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