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1
00:00:01,850 --> 00:00:05,086
WE ALL FLOAT
ALONG THE RIVER OF TIME.
2
00:00:05,087 --> 00:00:07,857
BUT DOES THAT RIVER
HAVE A SOURCE?
3
00:00:09,125 --> 00:00:11,125
HOW WAS TIME UNLEASHED?
4
00:00:11,126 --> 00:00:16,397
SOME BELIEVE TIME
FLOWS SMOOTHLY AND ETERNALLY.
5
00:00:16,398 --> 00:00:20,033
OTHERS SAY
IT DOESN'T FLOW AT ALL --
6
00:00:20,034 --> 00:00:23,405
IT POPS INTO EXISTENCE
EVERY FRACTION OF A SECOND.
7
00:00:25,475 --> 00:00:28,708
THE FINEST MINDS
IN PHYSICS CAN'T AGREE.
8
00:00:28,709 --> 00:00:31,779
BUT NEW EXPERIMENTS
MAY HOLD THE ANSWER
9
00:00:31,780 --> 00:00:37,986
TO THE GREATEST UNSOLVED MYSTERY
IN THE HISTORY OF THE UNIVERSE.
10
00:00:37,987 --> 00:00:39,086
THE MYSTERY...
11
00:00:39,087 --> 00:00:42,892
OF WHEN TIME BEGAN.
12
00:00:46,627 --> 00:00:48,196
SPACE...
13
00:00:48,197 --> 00:00:49,563
TIME...
14
00:00:49,564 --> 00:00:51,099
LIFE ITSELF.
15
00:00:53,602 --> 00:00:59,107
THE SECRETS OF THE COSMOS
LIE THROUGH THE WORMHOLE.
16
00:01:12,329 --> 00:01:14,899
WHEN WERE YOU BORN?
17
00:01:14,968 --> 00:01:17,069
SOUNDS LIKE A SIMPLE QUESTION.
18
00:01:17,126 --> 00:01:20,395
YOU JUST SAY A CERTAIN YEAR,
A MONTH, AND DAY.
19
00:01:20,483 --> 00:01:24,084
BUT AROUND THE WORLD,
WE RECKON TIME DIFFERENTLY.
20
00:01:24,180 --> 00:01:27,283
IN SAUDI ARABIA,
IT'S THE 15th CENTURY.
21
00:01:27,367 --> 00:01:30,169
IN ISRAEL, IT'S THE 58th.
22
00:01:30,244 --> 00:01:34,047
AND WE LIVE IN
24 DIFFERENT TIME ZONES.
23
00:01:34,149 --> 00:01:38,151
WE ALL MEASURE TIME RELATIVE
TO SOME STARTING POINT --
24
00:01:38,259 --> 00:01:40,027
A POINT WE HAVE CHOSEN.
25
00:01:40,075 --> 00:01:43,443
BUT IF WE REALLY WANT TO KNOW
WHAT TIME IT IS,
26
00:01:43,533 --> 00:01:48,204
WE NEED TO KNOW WHEN THE COSMIC
CLOCK STARTED TO TICK.
27
00:01:48,329 --> 00:01:52,099
DID TIME BEGIN
WHEN THE UNIVERSE BEGAN?
28
00:01:52,200 --> 00:01:54,670
OR DID IT START SOME OTHER WAY?
29
00:01:58,504 --> 00:02:00,904
ONCE, I WAS IN A BIKE RACE.
30
00:02:00,969 --> 00:02:04,841
I WANTED TO IMPRESS SOME FRIENDS
WITH MY TERRIFIC SPEED.
31
00:02:06,964 --> 00:02:11,232
SO I GAVE IT EVERYTHING I HAD.
32
00:02:11,346 --> 00:02:17,185
IT WAS A CLOSE RACE -- SO CLOSE,
I THOUGHT IT WAS A TIE.
33
00:02:17,341 --> 00:02:19,978
ONE KID SAID
MY OPPONENT WAS QUICKEST.
34
00:02:20,049 --> 00:02:23,118
BUT ANOTHER SAID I WAS FASTER.
35
00:02:23,201 --> 00:02:27,271
SO, WHOSE PERCEPTION OF TIME
WAS CORRECT?
36
00:02:27,380 --> 00:02:33,051
IN A WAY, WE WERE ALL RIGHT.
37
00:02:33,202 --> 00:02:37,204
TIME IS A MEASURE OF CHANGE.
38
00:02:39,915 --> 00:02:43,051
BUT HOW DO
WE KNOW THINGS CHANGE?
39
00:02:43,135 --> 00:02:46,037
WE RELY ON WHAT
OUR SENSES TELL US,
40
00:02:46,115 --> 00:02:49,483
AND PRIMARILY,
WE RELY ON WHAT WE CAN SEE.
41
00:02:49,574 --> 00:02:52,644
WE RELY ON LIGHT.
42
00:02:52,726 --> 00:02:54,726
IN THE VACUUM OF SPACE,
43
00:02:54,780 --> 00:02:59,985
LIGHT TRAVELS AT A FIXED SPEED
OF 186,000 MILES PER SECOND.
44
00:03:00,125 --> 00:03:04,396
THIS IS ACCEPTED AS AN ABSOLUTE
TRUTH OF THE UNIVERSE.
45
00:03:05,434 --> 00:03:09,737
AND THAT,
SAYS COSMOLOGIST JANNA LEVIN,
46
00:03:09,852 --> 00:03:13,989
GIVES LIGHT A UNIQUE
RELATIONSHIP TO TIME.
47
00:03:14,100 --> 00:03:16,502
IT'S ACTUALLY
COMPLETELY REMARKABLE
48
00:03:16,567 --> 00:03:18,801
THAT THE SPEED OF LIGHT
IS AN ABSOLUTE.
49
00:03:18,861 --> 00:03:21,029
IT'S NEVER FASTER.
IT'S NEVER SLOWER.
50
00:03:21,088 --> 00:03:23,489
TO UNDERSTAND
THE RELATIVITY OF TIME,
51
00:03:23,554 --> 00:03:25,522
WE REALLY NEED
TO UNDERSTAND LIGHT,
52
00:03:25,575 --> 00:03:28,009
AND ONCE WE START THINKING ABOUT
THE NATURE OF LIGHT,
53
00:03:28,074 --> 00:03:30,477
ALL OF OUR FAMILIAR INTUITIONS
ARE TURNED ON THEIR HEADS.
54
00:03:31,466 --> 00:03:33,835
IF THE SPEED OF LIGHT
IS CONSTANT,
55
00:03:34,207 --> 00:03:37,744
THEN TIME AND SPACE
MUST SHIFT AND DISTORT
56
00:03:37,839 --> 00:03:42,309
DEPENDING ON YOUR PARTICULAR
POINT OF VIEW.
57
00:03:42,429 --> 00:03:45,898
EINSTEIN HAD
THIS VERY PROFOUND INSIGHT
58
00:03:45,991 --> 00:03:48,994
WHEN HE STARTED TO THINK ABOUT
SOMETHING AS SIMPLE AS LIGHT,
59
00:03:49,075 --> 00:03:53,511
AND HE REALIZED THAT IF LIGHT
WAS GOING TO BE THE SAME
60
00:03:53,629 --> 00:03:56,029
FOR EVERYBODY IN THE UNIVERSE
61
00:03:56,094 --> 00:03:58,096
REGARDLESS OF HOW FAST
THEY WERE MOVING
62
00:03:58,150 --> 00:03:59,850
OR WHERE THEY WERE
IN THE UNIVERSE,
63
00:03:59,896 --> 00:04:01,763
THEN SPACE AND TIME
HAD TO BE DIFFERENT
64
00:04:01,814 --> 00:04:04,083
FOR DIFFERENT OBSERVERS.
65
00:04:04,144 --> 00:04:06,878
THIS MEANS TIME
IS VERY PERSONAL.
66
00:04:06,952 --> 00:04:11,657
IT DEPENDS ON WHERE YOU ARE
AND HOW FAST YOU ARE MOVING.
67
00:04:11,783 --> 00:04:14,819
AND THE WAY YOU SEE
YOUR MOVEMENT THROUGH TIME
68
00:04:14,900 --> 00:04:19,270
MAY NOT BE THE WAY OTHERS
SEE YOUR MOVEMENT THROUGH TIME.
69
00:04:22,470 --> 00:04:26,240
SAY, FOR INSTANCE,
JANNA HAS A DOPPELGANGER
70
00:04:26,341 --> 00:04:29,643
THAT RIDES THE SUBWAYS
AND TAXIS OF NEW YORK.
71
00:04:31,000 --> 00:04:34,769
IF JANNA'S DOPPELGANGER
GETS IN A CAB
72
00:04:34,870 --> 00:04:37,405
AND THAT CAB TRAVELS
AT INCREDIBLE SPEEDS...
73
00:04:40,864 --> 00:04:43,966
...TIME WILL FLOW DIFFERENTLY
FOR EACH WOMAN.
74
00:04:44,049 --> 00:04:47,486
IF SHE FLIES PAST ME IN A TAXI,
75
00:04:47,579 --> 00:04:51,248
IT WILL APPEAR TO ME
THAT HER TIME IS RUNNING SLOWER.
76
00:04:51,346 --> 00:04:55,249
FROM MY DOPPELGANGER'S POINT OF
VIEW, THE STREET WITH ME ON IT,
77
00:04:55,354 --> 00:04:57,755
WE'RE FLYING PAST HER
IN THE OPPOSITE DIRECTION,
78
00:04:57,819 --> 00:04:59,986
AND AS FAR AS SHE'S CONCERNED,
HER TIME IS NORMAL.
79
00:05:00,045 --> 00:05:02,548
IT'S MY TIME
THAT'S RUNNING SLOW.
80
00:05:02,718 --> 00:05:07,255
TO UNDERSTAND WHY THIS HAPPENS,
81
00:05:07,377 --> 00:05:11,146
IMAGINE JANNA TURNS ON
A DOUBLE-SIDED LASER
82
00:05:11,247 --> 00:05:15,250
WHOSE PULSING BEAMS BOUNCE OFF
THE SIDEWALK BELOW HER
83
00:05:15,357 --> 00:05:17,258
AND THE BALCONY ABOVE HER HEAD.
84
00:05:17,309 --> 00:05:19,479
THE PULSES FORM A LIGHT CLOCK.
85
00:05:19,538 --> 00:05:23,407
EACH BOUNCE OF THE LASER BEAM
IS ONE TICK.
86
00:05:23,511 --> 00:05:26,246
JANNA SEES THE LIGHT
GO STRAIGHT UP AND DOWN,
87
00:05:26,319 --> 00:05:31,923
BUT HER CAB-RIDING DOUBLE
SEES SOMETHING QUITE DIFFERENT.
88
00:05:32,073 --> 00:05:33,841
FROM THE PERSPECTIVE OF THE CAB,
89
00:05:33,889 --> 00:05:37,725
THE LIGHT APPEARS TO TAKE
A LONG DIAGONAL
90
00:05:37,828 --> 00:05:42,431
AND SO SEEMS AS THOUGH MY CLOCK
IS TAKING TOO LONG TO TICK.
91
00:05:42,554 --> 00:05:45,023
SO IT SEEMS LIKE MY TIME
IS RUNNING SLOW.
92
00:05:45,090 --> 00:05:49,193
IF JANNA'S DOPPELGANGER
TURNS ON THE LASER IN THE TAXI,
93
00:05:49,303 --> 00:05:52,704
SHE WILL SEE THE BEAM HITTING
THE CEILING AND FLOOR
94
00:05:52,795 --> 00:05:54,930
RIGHT ABOVE AND BELOW HER.
95
00:05:54,988 --> 00:05:58,760
BUT THE JANNA ON THE STREET
SEES THE BEAM MOVE DIAGONALLY.
96
00:05:59,580 --> 00:06:05,151
BECAUSE THE BEAM HAS LONGER TO
TRAVEL, ITS TICK LOOKS SLOWER.
97
00:06:05,299 --> 00:06:07,065
FROM MY PERSPECTIVE
ON THE STREET,
98
00:06:07,113 --> 00:06:08,514
IF I'M LOOKING INTO THE TAXI,
99
00:06:08,553 --> 00:06:11,321
I SEE THEIR LIGHT
TAKE A LONG DIAGONAL,
100
00:06:11,395 --> 00:06:15,066
AND SO I THINK IT'S TAKING
THEIR CLOCK TOO LONG TO TICK.
101
00:06:15,165 --> 00:06:18,034
FROM MY PERSPECTIVE,
THEIR CLOCKS ARE RUNNING SLOW.
102
00:06:18,487 --> 00:06:23,191
THE EFFECT INCREASES
THE FASTER YOU GO.
103
00:06:23,317 --> 00:06:26,218
IF THE CAB APPROACHES
THE SPEED OF LIGHT,
104
00:06:26,296 --> 00:06:28,631
THE SPEED LIMIT OF THE UNIVERSE,
105
00:06:28,694 --> 00:06:33,131
TIME OUTSIDE THE CAB
APPEARS TO STAND STILL.
106
00:06:33,250 --> 00:06:36,419
IF THAT TAXI WAS TO FLY BY
AT THE SPEED OF LIGHT,
107
00:06:36,504 --> 00:06:39,239
IT WOULD LOOK LIKE MY CLOCK
WAS NEVER GOING TO TICK,
108
00:06:39,313 --> 00:06:42,915
LIKE MY TIME HAD STOOD STILL,
LIKE TIME WAS FROZEN.
109
00:06:43,012 --> 00:06:46,247
SO, WHICH OBSERVER IS CORRECT?
110
00:06:46,334 --> 00:06:49,003
THE JANNA WHO'S STANDING STILL?
111
00:06:49,074 --> 00:06:50,941
OR THE JANNA IN MOTION?
112
00:06:50,992 --> 00:06:54,128
MY DOPPELGANGER AND I
JUST FUNDAMENTALLY DISAGREE
113
00:06:54,212 --> 00:06:55,545
ON THE PASSAGE OF TIME,
114
00:06:55,582 --> 00:06:56,850
AND IT'S TRUE.
115
00:06:56,884 --> 00:06:59,819
WE'RE BOTH RIGHT --
TIME IS RELATIVE.
116
00:06:59,898 --> 00:07:05,169
RELATIVITY MEANS THAT THERE CAN
BE NO SINGLE UNIVERSAL TIME.
117
00:07:05,310 --> 00:07:09,681
HOWEVER, THERE WAS ONE MOMENT
WHEN ALL PERSPECTIVES ON TIME
118
00:07:09,798 --> 00:07:12,098
MUST HAVE BEEN THE SAME --
119
00:07:12,161 --> 00:07:15,632
A MOMENT WHEN EVERYTHING EXISTED
IN ONE SINGLE PLACE...
120
00:07:16,854 --> 00:07:19,156
THE BIG BANG.
121
00:07:19,218 --> 00:07:22,419
ONE OF THE HARDEST THINGS
TO GRASP ABOUT THE IDEA
122
00:07:22,505 --> 00:07:25,307
OF THE BIG BANG
AND THE CREATION OF THE UNIVERSE
123
00:07:25,382 --> 00:07:30,888
IS THE IDEA THAT TIME ITSELF MAY
HAVE BEGUN IN THAT BIG EVENT,
124
00:07:31,036 --> 00:07:36,907
THAT SPACE WAS CREATED IN THE
BIG BANG AND TIME BEGAN TO TICK.
125
00:07:37,064 --> 00:07:40,399
BEFORE OUR BIG BANG, THERE MIGHT
NOT HAVE BEEN SPACE OR TIME.
126
00:07:40,591 --> 00:07:44,362
JANNA BELIEVES
THE BIG BANG WAS PROBABLY
127
00:07:44,463 --> 00:07:48,632
WHEN ALL THE VARIOUS TIME
STREAMS IN THE UNIVERSE BEGAN
128
00:07:48,744 --> 00:07:52,347
AND THAT, SINCE THEN,
TIME HAS PASSED DIFFERENTLY
129
00:07:52,443 --> 00:07:57,848
IN DIFFERENT PLACES DEPENDING
ON HOW THOSE PLACES HAVE MOVED.
130
00:07:57,993 --> 00:08:00,727
BUT COULD WE CREATE PLACES
IN OUR UNIVERSE
131
00:08:00,800 --> 00:08:05,806
WHERE TIME CAN APPEAR TO STOP
AND THEN BEGIN AGAIN?
132
00:08:05,940 --> 00:08:08,809
IF WE COULD HIDE AN EVENT
FROM LIGHT,
133
00:08:08,886 --> 00:08:11,522
COULD WE ALSO HIDE IT FROM TIME?
134
00:08:13,887 --> 00:08:15,955
THESE ARE QUESTIONS
135
00:08:16,011 --> 00:08:19,813
PROFESSOR ALEX GAETA
ASKED HIMSELF.
136
00:08:19,915 --> 00:08:22,085
A FORMER
COMPETITION-TENNIS PLAYER,
137
00:08:23,167 --> 00:08:24,869
ALEX IS A PHYSICIST
AT CORNELL UNIVERSITY
138
00:08:24,915 --> 00:08:29,319
SPECIALIZING
IN ULTRA-FAST OPTICS.
139
00:08:29,437 --> 00:08:31,939
THIS TECHNOLOGY IS USUALLY USED
140
00:08:32,006 --> 00:08:34,941
FOR HIGH-SPEED DATA
TRANSMISSION.
141
00:08:35,020 --> 00:08:36,920
BUT AFTER READING A PAPER
142
00:08:36,972 --> 00:08:40,109
WRITTEN BY THEORISTS
AT IMPERIAL COLLEGE,
143
00:08:40,193 --> 00:08:44,563
HE REALIZED IT
COULD ALSO CREATE A GAP IN TIME.
144
00:08:44,680 --> 00:08:47,048
YOU KNOW, LIGHT IS
AN ELECTROMAGNETIC DISTURBANCE.
145
00:08:47,112 --> 00:08:48,845
THE MINUTE THINGS START
CHANGING,
146
00:08:48,892 --> 00:08:50,994
THAT'S AN INDICATION
THAT TIME IS PASSING.
147
00:08:51,051 --> 00:08:53,618
SO ALL THESE CHANGES
THAT ARE OCCURRING
148
00:08:53,687 --> 00:08:55,956
ARE CREATING ALL THESE
ELECTROMAGNETIC DISTURBANCES
149
00:08:56,017 --> 00:09:00,520
THAT WE CAN DETECT
AND MEASURE AS PASSAGE OF TIME.
150
00:09:00,641 --> 00:09:02,675
WHAT WE'VE FIGURED OUT
IS A WAY
151
00:09:02,730 --> 00:09:05,800
OF ESSENTIALLY
TURNING OFF THE LIGHTS,
152
00:09:05,882 --> 00:09:07,482
TURNING THEM BACK ON WITHOUT,
YOU KNOW,
153
00:09:07,526 --> 00:09:10,864
YOU SENSING THAT THEY'VE EVER
ACTUALLY BEEN TURNED OFF.
154
00:09:14,959 --> 00:09:17,694
WHAT WOULD HAPPEN
IF YOU TURNED OFF
155
00:09:17,768 --> 00:09:19,170
THE LIGHT SHINING ON TIME
156
00:09:19,208 --> 00:09:21,608
LONG ENOUGH TO HIDE AN EVENT?
157
00:09:21,673 --> 00:09:27,613
SAY, FOR INSTANCE, ALEX IS IN
A CLOSE GAME WITH HIS SON, MAX.
158
00:09:27,772 --> 00:09:31,608
HE'S COMING UP TO MATCH POINT,
AND HE WANTS TO WIN.
159
00:09:31,710 --> 00:09:36,012
IF ALEX COULD CREATE
A HOLE IN TIME,
160
00:09:36,128 --> 00:09:38,297
NO ONE COULD SEE HIM DO THIS...
161
00:09:42,191 --> 00:09:48,329
TO OBSERVERS, INCLUDING HIS SON,
ALEX WINS THE SET WITHOUT PAUSE.
162
00:09:50,926 --> 00:09:54,729
RIGHT NOW, THIS IS IMPOSSIBLE.
163
00:09:54,831 --> 00:09:58,301
BUT ALL GREAT THINGS
START SMALL.
164
00:09:59,729 --> 00:10:05,068
THIS IS THE KEY COMPONENT
OF ALEX'S EXPERIMENT --
165
00:10:05,211 --> 00:10:06,978
THE SPLIT-TIME LENS.
166
00:10:08,156 --> 00:10:10,825
IT FOCUSES LIGHT SIGNALS
AND TIME
167
00:10:10,897 --> 00:10:14,266
THE WAY A GLASS LENS
FOCUSES LIGHT IN SPACE.
168
00:10:14,356 --> 00:10:17,991
IN A VACUUM,
THE SPEED OF LIGHT IS CONSTANT,
169
00:10:18,089 --> 00:10:22,726
BUT THAT SPEED CHANGES WHEN
LIGHT PASSES THROUGH A MATERIAL
170
00:10:22,850 --> 00:10:26,052
OR WHEN IT RUNS INTO
ANOTHER LIGHT BEAM.
171
00:10:26,138 --> 00:10:30,543
ALEX'S SPLIT-TIME LENS
USES BOTH TRICKS.
172
00:10:30,661 --> 00:10:34,796
ALEX SHOOTS A LASER
INTO A BEAM OF LIGHT,
173
00:10:34,907 --> 00:10:36,842
SLOWING IT EVER SO SLIGHTLY.
174
00:10:36,894 --> 00:10:39,997
THE BEAM THEN PASSES THROUGH
A GLASS FIBER
175
00:10:40,080 --> 00:10:42,247
WHERE IT SPLITS INTO TWO PARTS,
176
00:10:42,306 --> 00:10:44,640
EACH WITH
A DIFFERENT WAVELENGTH.
177
00:10:44,703 --> 00:10:48,807
THE LOWER WAVELENGTH PULLS AHEAD
OF THE HIGHER WAVELENGTH,
178
00:10:48,917 --> 00:10:51,585
LEAVING A GAP
OF ABSOLUTE DARKNESS.
179
00:10:51,657 --> 00:10:55,593
ANYTHING WITHIN THAT GAP
IS IMPOSSIBLE TO OBSERVE
180
00:10:55,698 --> 00:10:58,066
SINCE THERE IS NO LIGHT THERE.
181
00:10:58,130 --> 00:11:00,698
THE LIGHT THEN PASSES THROUGH
ANOTHER TIME LENS
182
00:11:00,767 --> 00:11:04,572
THAT RE-UNIFIES THE BEAM
WITH NO VISIBLE CHANGE.
183
00:11:08,476 --> 00:11:10,645
USING THIS DEVICE,
184
00:11:10,703 --> 00:11:16,207
ALEX HAS CREATED GAPS THAT LAST
ALMOST A BILLIONTH OF A SECOND.
185
00:11:16,355 --> 00:11:18,257
THAT MAY NOT SOUND LIKE MUCH,
186
00:11:18,308 --> 00:11:21,708
BUT IN THE WORLD OF HIGH-SPEED
INFORMATION TRANSFER,
187
00:11:21,799 --> 00:11:23,402
IT'S SIGNIFICANT.
188
00:11:23,446 --> 00:11:25,513
LET'S SAY YOU HAVE
A DATA STREAM
189
00:11:25,569 --> 00:11:27,737
AND YOU DON'T WANT
TO INTERRUPT IT AT ALL
190
00:11:27,795 --> 00:11:29,761
BUT YOU WANT TO PUT
SOME INFORMATION
191
00:11:29,815 --> 00:11:30,948
INTO THAT DATA STREAM
192
00:11:30,979 --> 00:11:32,079
AND THEN TAKE IT OUT.
193
00:11:32,109 --> 00:11:34,211
SO, BY CREATING THIS GAP,
194
00:11:34,268 --> 00:11:37,337
YOU CAN CREATE THE GAP,
NOT DISTURB THE LIGHT STREAM,
195
00:11:37,419 --> 00:11:39,888
INSERT A LITTLE BIT OF DATA,
TRANSMIT IT,
196
00:11:39,955 --> 00:11:41,689
AND THEN LATER ON,
PULL OUT THAT DATA
197
00:11:41,941 --> 00:11:45,178
AND THEN PUT
THE DATA STREAM BACK TOGETHER.
198
00:11:45,265 --> 00:11:49,836
AND THAT INFORMATION WOULD BE
HIDDEN FROM THE PASSAGE OF TIME.
199
00:11:51,738 --> 00:11:57,110
TODAY, CREATING A LIGHT GAP
THAT LASTS FOR ONE SECOND
200
00:11:57,253 --> 00:12:02,324
WOULD REQUIRE
A MACHINE 186,000 MILES LONG.
201
00:12:02,460 --> 00:12:07,062
SO ALEX WILL HAVE TO WIN
HIS TENNIS MATCHES THE HARD WAY.
202
00:12:07,185 --> 00:12:10,989
BUT THE TECHNOLOGY
IS RAPIDLY EVOLVING.
203
00:12:11,091 --> 00:12:13,594
IN PRINCIPLE,
THERE HAVE BEEN DEMONSTRATIONS
204
00:12:13,662 --> 00:12:16,293
WHERE THEY CAN SLOW
DOWN LIGHT BY FACTORS
205
00:12:16,389 --> 00:12:18,368
OF 10 TO THE 7th, 10 TO THE 8th.
206
00:12:18,422 --> 00:12:20,022
IN THE NEAR FUTURE,
IT COULD BE EVEN MORE.
207
00:12:20,065 --> 00:12:22,467
YOU COULD ESSENTIALLY
ALMOST STOP LIGHT,
208
00:12:22,532 --> 00:12:25,733
STORE LIGHT FOR RELATIVELY LONG
PERIODS OF TIME, SECONDS,
209
00:12:25,819 --> 00:12:28,353
AND THEN ESSENTIALLY
RELEASE IT TO TRAVEL,
210
00:12:28,447 --> 00:12:30,425
AGAIN, BACK AT THE
SPEED OF LIGHT.
211
00:12:30,478 --> 00:12:34,848
ALEX AND JANNA'S WORK EXPLORES
THE DEEP CONNECTION
212
00:12:34,966 --> 00:12:38,902
BETWEEN OBSERVERS, LIGHT,
AND THE PASSAGE OF TIME.
213
00:12:39,007 --> 00:12:41,242
IT BEGS THE QUESTION,
214
00:12:41,302 --> 00:12:45,104
DOES TIME EXIST IF THERE
IS NO ONE AROUND TO SEE IT?
215
00:12:45,206 --> 00:12:48,575
ONE SCIENTIST SAYS NO --
216
00:12:48,666 --> 00:12:52,939
TIME BEGAN
MUCH LATER THAN WE THINK.
217
00:12:58,430 --> 00:13:01,199
HOW OFTEN HAVE YOU WOKEN UP
IN A DARKENED ROOM
218
00:13:01,274 --> 00:13:04,976
AND HAD NO IDEA
WHAT TIME IT WAS?
219
00:13:05,075 --> 00:13:10,947
HAVE YOU BEEN OUT
FOR MINUTES OR HOURS?
220
00:13:11,104 --> 00:13:16,341
WHEN YOU ARE SLEEPING, YOU HAVE
NO SENSE THAT TIME IS PASSING.
221
00:13:16,481 --> 00:13:20,652
PERHAPS THE COSMOS EXPERIENCES
TIME IN THE SAME WAY.
222
00:13:20,764 --> 00:13:23,932
THE BIG BANG WAS THE MOMENT
OUR UNIVERSE WAS BORN,
223
00:13:24,017 --> 00:13:29,122
BUT WHAT IF IT
DIDN'T WAKE UP RIGHT AWAY?
224
00:13:29,259 --> 00:13:34,797
COULD THERE HAVE BEEN A TIME
WHEN THE UNIVERSE HAD NO TIME?
225
00:13:40,077 --> 00:13:43,480
PROFESSOR LARRY SCHULMAN
IS A LITTLE OUT OF PLACE
226
00:13:43,571 --> 00:13:45,038
IN DRESDEN, GERMANY.
227
00:13:45,078 --> 00:13:48,647
HIS HOME BASE IS NEW YORK'S
CLARKSON UNIVERSITY,
228
00:13:48,743 --> 00:13:52,146
WHICH OFTEN SITS UNDER
A STATIC SHEET OF ICE.
229
00:13:52,237 --> 00:13:54,172
NOT SO DIFFERENT, LARRY SAYS,
230
00:13:54,225 --> 00:13:56,860
FROM THE STATE
OF THE EARLY UNIVERSE,
231
00:13:56,931 --> 00:14:01,035
WHEN, HE CLAIMS,
TIME DID NOT EXIST.
232
00:14:04,295 --> 00:14:07,295
LARRY EXPLORES
THE BEHAVIOR OF SYSTEMS
233
00:14:07,376 --> 00:14:09,678
COMPOSED OF LARGE NUMBERS
OF PARTICLES
234
00:14:09,740 --> 00:14:11,910
SUCH AS THE WATER IN
THIS FOUNTAIN OR THE UNIVERSE.
235
00:14:12,482 --> 00:14:15,650
STATISTICAL MECHANICS
CAN ALSO TELL US ABOUT
236
00:14:15,735 --> 00:14:18,304
THE RELATIONSHIP
OF LIGHT TO TIME.
237
00:14:19,811 --> 00:14:22,079
LIGHT CARRIES INFORMATION
ABOUT EVENTS.
238
00:14:22,141 --> 00:14:26,712
WE USE IT TO DETERMINE
WHAT IS HAPPENING NOW.
239
00:14:26,834 --> 00:14:29,069
BUT BECAUSE LIGHT
HAS A SPEED LIMIT,
240
00:14:29,129 --> 00:14:34,532
EVERYTHING WE SEE
ACTUALLY TOOK PLACE IN THE PAST.
241
00:14:34,677 --> 00:14:37,879
THE TIME IT WOULD TAKE,
FOR EXAMPLE, FROM THE SUN
242
00:14:37,965 --> 00:14:40,568
IS ABOUT 8 MINUTES
BECAUSE IT'S 93 MILLION MILES,
243
00:14:40,638 --> 00:14:43,806
AND YOU FIGURE WITH A VELOCITY
OF 186,000 MILES PER SECOND,
244
00:14:43,891 --> 00:14:46,058
THAT'S HOW LONG
THE LIGHT WOULD TAKE.
245
00:14:46,117 --> 00:14:49,154
SO, IF THE SUN WERE TO EXPLODE,
FOR EXAMPLE,
246
00:14:49,235 --> 00:14:50,734
YOU WOULD NOT KNOW ABOUT IT
247
00:14:50,775 --> 00:14:52,546
UNTIL EIGHT MINUTES
AFTER THE EVENT.
248
00:14:53,929 --> 00:14:56,563
THE LIGHT OF THE MOST
DISTANT PARTS OF THE UNIVERSE
249
00:14:56,634 --> 00:15:01,272
HAS BEEN TRAVELING TOWARD US
FOR 13.8 BILLION YEARS.
250
00:15:01,396 --> 00:15:05,367
THIS IS WHEN THE UNIVERSE BEGAN
IN THE BIG BANG.
251
00:15:08,967 --> 00:15:10,768
THE EARLY UNIVERSE WAS NOTHING
252
00:15:10,816 --> 00:15:12,983
BUT A FIELD
OF CHARGED PARTICLES,
253
00:15:13,042 --> 00:15:16,544
A DENSE, HOT CLOUD OF PLASMA.
254
00:15:16,638 --> 00:15:19,006
PHOTONS, PARTICLES OF LIGHT,
255
00:15:19,070 --> 00:15:23,241
COULD NOT TRAVEL VERY FAR
IN THIS SOUP.
256
00:15:23,353 --> 00:15:27,656
THEN ABOUT 380,000 YEARS
INTO THE LIFE OF THE UNIVERSE,
257
00:15:27,771 --> 00:15:32,174
THERE WAS A SUDDEN CHANGE
CALLED RECOMBINATION.
258
00:15:32,292 --> 00:15:35,694
THIS IS WHEN ATOMS
BEGAN TO FORM.
259
00:15:35,785 --> 00:15:37,254
PRIOR TO RECOMBINATION,
260
00:15:37,294 --> 00:15:38,694
IF AN ELECTRON AND A PROTON
261
00:15:38,732 --> 00:15:41,332
WOULD APPROACH
AND BIND TEMPORARILY,
262
00:15:41,402 --> 00:15:44,170
THEY WOULD BE WHACKED
BY A PHOTON COMING ALONG
263
00:15:44,245 --> 00:15:45,546
AND BE KNOCKED APART.
264
00:15:45,581 --> 00:15:48,115
RECOMBINATION IS A PROCESS
265
00:15:48,184 --> 00:15:50,320
IN WHICH THE ELECTRONS
AND THE PROTONS,
266
00:15:50,377 --> 00:15:51,811
WHICH WERE PREVIOUSLY LOOSE
267
00:15:51,851 --> 00:15:54,218
AND SEPARATED FROM EACH OTHER
IN THE PLASMA,
268
00:15:54,281 --> 00:15:56,417
FINALLY CAN GET TOGETHER.
269
00:15:57,091 --> 00:16:01,863
IT'S A BIT LIKE HOCKEY.
270
00:16:01,991 --> 00:16:06,260
IF YOU IMAGINE
THE HOCKEY PUCK IS A PHOTON.
271
00:16:06,374 --> 00:16:12,278
THIS IS THE RIVER ELBE,
AND SOMETIMES IT FREEZES OVER.
272
00:16:12,436 --> 00:16:14,204
SUPPOSING I WOULD WAIT FOR THAT
273
00:16:14,252 --> 00:16:16,520
AND GO OUT THERE
WITH MY HOCKEY PUCK,
274
00:16:16,581 --> 00:16:19,651
I COULD KNOCK IT
TO THE BANK WITH NO PROBLEM.
275
00:16:19,734 --> 00:16:23,369
BUT THE UNIVERSE JUST AFTER THE
BIG BANG WAS FULL OF OBSTACLES.
276
00:16:23,466 --> 00:16:27,268
NOW SUPPOSE THAT SURROUNDING ME
WERE A BUNCH OF GOALIES
277
00:16:27,370 --> 00:16:28,772
NOT PROTECTING A GOAL,
278
00:16:28,810 --> 00:16:32,011
BUT JUST MAKING SURE THAT
MY HOCKEY PUCK DIDN'T PASS THEM.
279
00:16:32,097 --> 00:16:34,466
SO ALL THESE GOALIES
ARE STANDING AROUND,
280
00:16:34,530 --> 00:16:37,466
AND EVERY TIME I HIT THE PUCK,
ONE OF THEM STOPS IT.
281
00:16:37,545 --> 00:16:39,447
THIS PUCK
IS NOT GONNA GET THROUGH.
282
00:16:39,499 --> 00:16:43,467
THIS, LARRY SAYS,
IS THE EARLY UNIVERSE.
283
00:16:43,573 --> 00:16:47,475
PHOTON PUCKS COULDN'T GET PAST
THE ELECTRON AND PROTON GOALIES,
284
00:16:47,580 --> 00:16:51,117
SO LIGHT DIDN'T FLOW.
285
00:16:51,212 --> 00:16:54,814
ON THE OTHER HAND, THESE GOALIES
ARE A LITTLE BIT UNUSUAL,
286
00:16:54,910 --> 00:16:56,879
AND THEY ALTERNATE BOY, GIRL,
BOY, GIRL,
287
00:16:56,933 --> 00:16:59,801
BUT AT FIRST, THEY DIDN'T KNOW
THAT BECAUSE OF THEIR BIG MASKS.
288
00:16:59,878 --> 00:17:02,280
AFTER A WHILE, ONE OF THEM
REMOVES THE MASK,
289
00:17:02,345 --> 00:17:04,445
AND THE GUY NEXT TO HER
SAYS, "OH."
290
00:17:04,501 --> 00:17:05,769
HMM.
291
00:17:05,804 --> 00:17:08,238
THEN THE PUCK
CAN GET RIGHT THROUGH.
292
00:17:08,304 --> 00:17:10,805
ONCE THE PHOTONS
COULD ESCAPE EASILY,
293
00:17:10,872 --> 00:17:12,939
THE WORLD
CHANGED DRAMATICALLY.
294
00:17:14,949 --> 00:17:19,454
IN THE EARLY UNIVERSE,
PHOTONS COULD NEVER MOVE FREELY,
295
00:17:19,574 --> 00:17:22,042
AND THERE WAS NO WAY
TO MEASURE CHANGE.
296
00:17:22,109 --> 00:17:26,978
LARRY ARGUES,
THAT MEANS TIME DID NOT EXIST.
297
00:17:27,108 --> 00:17:29,743
ONLY AFTER RECOMBINATION,
298
00:17:29,814 --> 00:17:33,083
WHEN THE UNIVERSE COOLED
AND ATOMS FORMED,
299
00:17:33,171 --> 00:17:36,107
DID LIGHT BEGIN
TO MOVE AROUND FREELY.
300
00:17:36,186 --> 00:17:42,125
THAT, SAYS LARRY, IS WHEN THE
UNIVERSE'S CLOCK BEGAN TO TICK.
301
00:17:42,283 --> 00:17:45,951
THE VERY EARLIEST POINT,
THERE'S NEVER EVEN A TIME.
302
00:17:46,050 --> 00:17:48,419
BUT EVENTUALLY,
THERE WAS SOMETHING CALLED TIME,
303
00:17:48,483 --> 00:17:51,953
WHICH WAS KEEPING TRACK
OF THE WAY THINGS CHANGED.
304
00:17:52,115 --> 00:17:55,084
THIS COULD EXPLAIN THE BIRTH
OF TIME IN OUR UNIVERSE.
305
00:17:56,841 --> 00:18:03,380
BUT IF OUR UNIVERSE ENDS,
WILL TIME DIE WITH IT?
306
00:18:03,555 --> 00:18:08,292
THIS PHYSICIST THINKS TIME
IS TRULY FUNDAMENTAL --
307
00:18:08,418 --> 00:18:10,353
TIME IS ALWAYS HERE.
308
00:18:10,406 --> 00:18:13,108
IT IS SPACE THAT COMES AND GOES.
309
00:18:15,715 --> 00:18:20,685
TIME MOVES FORWARD,
NEVER BACKWARD.
310
00:18:20,818 --> 00:18:25,924
PHYSICISTS SAY THAT IS BECAUSE
ENERGY ALWAYS DISSIPATES.
311
00:18:27,943 --> 00:18:30,312
IF YOU WIND TIME BACK
FAR ENOUGH,
312
00:18:30,376 --> 00:18:35,613
YOU WOULD SEE THE ENTIRE ENERGY
OF THE UNIVERSE COMING TOGETHER.
313
00:18:35,753 --> 00:18:40,923
AT THE BIG BANG, EVERYTHING
IS FOCUSED ON A SINGLE POINT.
314
00:18:41,061 --> 00:18:45,299
YOU CAN'T WIND TIME BACK
ANY MORE THAN THIS.
315
00:18:45,413 --> 00:18:47,680
OR CAN YOU?
316
00:18:47,741 --> 00:18:51,645
PHYSICIST SEAN CARROLL
317
00:18:51,750 --> 00:18:54,218
OF THE CALIFORNIA INSTITUTE
OF TECHNOLOGY
318
00:18:54,284 --> 00:18:57,486
HAS SPENT MUCH OF HIS CAREER
CONTEMPLATING TIME.
319
00:18:57,572 --> 00:19:01,507
THOUGH THE ORIGIN OF TIME
IS A MYSTERY,
320
00:19:01,613 --> 00:19:03,849
SEAN IS CERTAIN OF ONE THING --
321
00:19:03,909 --> 00:19:07,145
IN OUR UNIVERSE,
TIME HAS A DIRECTION,
322
00:19:07,848 --> 00:19:11,417
AN ARROW
THAT RUNS THROUGH EVERYTHING.
323
00:19:11,513 --> 00:19:17,419
TIME IS A MEASURE OF CHANGE
IN THE UNIVERSE.
324
00:19:17,577 --> 00:19:19,746
IF NOTHING WERE CHANGING
IN THE WORLD,
325
00:19:19,804 --> 00:19:22,037
THERE'D BE NO WAY OF KNOWING
THAT TIME WAS PASSING.
326
00:19:22,098 --> 00:19:24,200
EVERYTHING WOULD BE THE SAME
AT EVERY SINGLE MOMENT.
327
00:19:24,257 --> 00:19:25,389
THERE'D BE NO CLOCKS.
328
00:19:25,420 --> 00:19:27,555
TIME ITSELF WOULD BASICALLY
HAVE NO MEANING.
329
00:19:30,458 --> 00:19:33,994
AS LONG AS SOMETHING IS
CHANGING, NO MATTER HOW SMALL,
330
00:19:34,089 --> 00:19:36,656
TIME IS FLOWING.
331
00:19:36,725 --> 00:19:41,595
AND OUR UNIVERSE IS IN
A CONSTANT STATE OF CHANGE.
332
00:19:41,725 --> 00:19:43,626
AT THE DAWN OF THE UNIVERSE,
333
00:19:43,678 --> 00:19:48,582
AN ENORMOUS AMOUNT OF ENERGY WAS
COMPRESSED INTO A SINGLE POINT.
334
00:19:48,713 --> 00:19:50,682
THEN CAME THE BIG BANG.
335
00:19:51,112 --> 00:19:54,214
SINCE THEN,
WITH EVERY PASSING SECOND,
336
00:19:54,297 --> 00:19:57,834
THAT ENERGY HAS BECOME
MORE AND MORE SPREAD OUT.
337
00:19:57,929 --> 00:20:02,966
THE MEASURE OF THAT SPREADING
OF ENERGY IS CALLED ENTROPY.
338
00:20:03,101 --> 00:20:07,970
SEAN BELIEVES THE FORWARD
MOVEMENT OF TIME, TIME'S ARROW,
339
00:20:08,100 --> 00:20:13,005
IS THE STEADY MOVEMENT FROM
LOW ENTROPY TO HIGH ENTROPY.
340
00:20:13,137 --> 00:20:17,407
BUT WHAT SET TIME'S ARROW
IN MOTION?
341
00:20:17,521 --> 00:20:19,321
THE PUZZLE THAT WE HAVE
342
00:20:19,370 --> 00:20:21,238
IS THAT ENTROPY
TENDS TO INCREASE,
343
00:20:21,288 --> 00:20:24,256
BUT OUR BIG BANG WAS A CONDITION
OF VERY, VERY LOW ENTROPY,
344
00:20:24,336 --> 00:20:26,772
SO HOW DID IT GET THAT WAY?
345
00:20:26,838 --> 00:20:28,673
WHERE COULD IT HAVE COME FROM?
346
00:20:28,723 --> 00:20:33,359
EVERYTHING WE KNOW IN PHYSICS
IS THINGS INCREASING IN ENTROPY.
347
00:20:33,483 --> 00:20:35,117
SO IF YOU GO BACK
TO THE BIG BANG,
348
00:20:35,161 --> 00:20:38,696
THERE WAS NO LOWER ENTROPY PLACE
IT COULD'VE COME FROM.
349
00:20:38,791 --> 00:20:41,627
SEAN SUSPECTS THE ANSWER
350
00:20:41,703 --> 00:20:45,374
IS THAT OUR UNIVERSE IS
THE CHILD OF ANOTHER UNIVERSE.
351
00:20:45,473 --> 00:20:48,307
BUT WHAT WAS THAT UNIVERSE LIKE?
352
00:20:48,383 --> 00:20:50,650
MAYBE LIKE THIS...
353
00:20:50,711 --> 00:20:53,014
IMAGINE A UNIVERSE
THAT'S IN EQUILIBRIUM.
354
00:20:53,076 --> 00:20:55,778
IT'S IN A HIGH-ENTROPY STATE.
IT'S EMPTIED OUT.
355
00:20:55,851 --> 00:20:57,417
IT'S JUST SITTING THERE QUIETLY,
356
00:20:57,460 --> 00:20:59,260
MUCH LIKE
THE WATER IN THIS TANK.
357
00:20:59,309 --> 00:21:02,278
YOU DON'T SEE ANY MOTION.
358
00:21:02,358 --> 00:21:04,693
NOW IMAGINE IN THIS UNIVERSE
359
00:21:04,756 --> 00:21:06,992
WHERE ALL THE ENERGY
IS DISSIPATED,
360
00:21:07,052 --> 00:21:11,621
SUDDENLY AN AREA OF DENSE ENERGY
POPS INTO EXISTENCE,
361
00:21:11,743 --> 00:21:15,879
MUCH LIKE THIS BAG
OF EFFERVESCENT TABLETS.
362
00:21:15,990 --> 00:21:18,859
THE SELTZER STARTS
SMALL AND DENSE AND LOW ENTROPY
363
00:21:18,936 --> 00:21:22,505
JUST LIKE OUR UNIVERSE DID NEAR
THE BIG BANG,
364
00:21:22,601 --> 00:21:25,803
BUT THEN WE EXPANDED AND COOLED,
GALAXIES FORMED,
365
00:21:25,889 --> 00:21:29,992
AND THE ARROW OF TIME
PROGRESSES FROM PAST TO FUTURE.
366
00:21:30,102 --> 00:21:32,938
LIKEWISE, THE SELTZER FIZZES
AND BECOMES HIGHER ENTROPY
367
00:21:33,014 --> 00:21:35,916
AS IT MIXES
WITH THE WATER AROUND IT.
368
00:21:35,994 --> 00:21:38,329
AND EVENTUALLY,
JUST LIKE OUR UNIVERSE
369
00:21:38,392 --> 00:21:40,058
WILL COME BACK TO EQUILIBRIUM
370
00:21:40,104 --> 00:21:42,172
AND THE ARROW OF TIME
WILL CEASE,
371
00:21:42,228 --> 00:21:43,829
THE SELTZER REACHES EQUILIBRIUM
372
00:21:43,872 --> 00:21:45,806
BY MIXING WITH
THE WATER AROUND IT,
373
00:21:45,858 --> 00:21:48,660
AND WE'RE BACK TO A STATE
THAT DOESN'T CHANGE ANYMORE,
374
00:21:48,736 --> 00:21:50,370
A STATE WITHOUT
ANY ARROW OF TIME.
375
00:21:50,517 --> 00:21:53,553
BUT HOW COULD A DEAD UNIVERSE,
376
00:21:53,635 --> 00:21:56,804
ONE WITH NO LIFE, STARS,
OR SOLID MATTER,
377
00:21:56,889 --> 00:22:00,593
GIVE BIRTH TO ANOTHER UNIVERSE?
378
00:22:02,381 --> 00:22:06,318
ACCORDING TO QUANTUM PHYSICS,
EVEN AN EMPTY VOID
379
00:22:06,424 --> 00:22:10,093
WILL EXPERIENCE TINY
FLUCTUATIONS OF ENERGY.
380
00:22:10,191 --> 00:22:13,893
THIS MEANS
THAT EVERY ONCE IN A WHILE,
381
00:22:13,993 --> 00:22:17,330
SOMETHING
CAN POP OUT OF NOTHING.
382
00:22:17,419 --> 00:22:20,890
THINK ABOUT THE ATOMIC NUCLEUS
OF A RADIOACTIVE ELEMENT.
383
00:22:20,983 --> 00:22:23,350
IT JUST SITS THERE.
YOU LOOK AT IT.
384
00:22:23,414 --> 00:22:25,815
IT'S NOT CHANGING
AS YOU LOOK AT IT,
385
00:22:25,880 --> 00:22:29,248
BUT THERE IS A POSSIBILITY EVERY
SECOND THAT IT WILL DECAY,
386
00:22:29,338 --> 00:22:31,640
THAT IT WILL SPIT OUT
A NEW PARTICLE.
387
00:22:31,703 --> 00:22:34,172
WHAT WE'RE SAYING IS THAT
SPACE-TIME ITSELF
388
00:22:34,238 --> 00:22:36,637
CAN BE RADIOACTIVE
JUST LIKE THAT NUCLEUS,
389
00:22:36,702 --> 00:22:39,604
EXCEPT INSTEAD OF SPITTING OUT
A NEW PARTICLE,
390
00:22:39,682 --> 00:22:42,986
IT CAN SPIT OUT
AN ENTIRELY NEW UNIVERSE.
391
00:22:43,075 --> 00:22:50,048
NEW UNIVERSES MAY CONSTANTLY
BE POPPING INTO EXISTENCE.
392
00:22:52,701 --> 00:22:56,637
A RANDOM QUANTUM FLUCTUATION
IN AN ANCIENT UNIVERSE --
393
00:22:56,742 --> 00:23:00,044
A UNIVERSE SO OLD,
TIME FELL APART --
394
00:23:00,133 --> 00:23:05,137
MIGHT EVEN HAVE GIVEN BIRTH
TO OUR UNIVERSE.
395
00:23:05,271 --> 00:23:07,972
THIS PROCESS OF STARTING
WITH NO ARROW OF TIME,
396
00:23:08,044 --> 00:23:10,713
BUDDING OFF A NEW UNIVERSE,
HAVING AN ARROW,
397
00:23:10,785 --> 00:23:12,986
AND THE ARROW ONLY LASTS
FOR A LITTLE WHILE
398
00:23:13,046 --> 00:23:14,881
AS THAT UNIVERSE
EXPANDS AND COOLS,
399
00:23:14,931 --> 00:23:17,466
BUT ONCE IT REACHES EQUILIBRIUM,
THE ARROW STOPS --
400
00:23:17,534 --> 00:23:19,869
THIS COULD HAPPEN MANY, MANY,
MANY, MANY TIMES.
401
00:23:19,932 --> 00:23:21,165
LET'S PUT IT THAT WAY --
402
00:23:21,199 --> 00:23:22,999
MAYBE AN INFINITE NUMBER
OF TIMES,
403
00:23:23,047 --> 00:23:25,382
BUT CERTAINLY
A VERY, VERY LARGE NUMBER,
404
00:23:25,445 --> 00:23:28,114
SO IT'S POSSIBLE
THAT THE UNIVERSE WE CAME FROM
405
00:23:28,186 --> 00:23:30,521
WAS NOWHERE NEAR THE FIRST.
406
00:23:31,205 --> 00:23:37,444
OUR BIG BANG MIGHT
NOT HAVE BEEN THE BEGINNING.
407
00:23:37,611 --> 00:23:41,489
OUR COSMOS' TIME COULD HAVE
ANCESTORS THAT PREDATED IT
408
00:23:41,490 --> 00:23:45,859
AND DESCENDENTS
AFTER THIS UNIVERSE IS GONE.
409
00:23:45,976 --> 00:23:50,114
BUT THERE MAY BE
AN EVEN DEEPER TRUTH ABOUT TIME,
410
00:23:50,225 --> 00:23:52,525
A TRUTH WE WILL NEVER LEARN
411
00:23:52,587 --> 00:23:57,692
UNTIL WE ACCEPT
THAT IT DOESN'T REALLY EXIST.
412
00:24:09,382 --> 00:24:12,017
WHAT WOULD WE DO WITHOUT TIME?
413
00:24:12,088 --> 00:24:16,526
HOW COULD WE KEEP TRACK
OF THE EVENTS IN OUR LIVES
414
00:24:16,645 --> 00:24:21,281
WITHOUT THE STEADY PULSE
OF MINUTES, DAYS, AND YEARS?
415
00:24:21,405 --> 00:24:25,909
BUT IT MAY BE
THAT NONE OF THAT IS REAL.
416
00:24:26,030 --> 00:24:29,465
IT MAY BE THAT TIME
417
00:24:29,557 --> 00:24:30,759
IS NOTHING MORE THAN A MIRAGE.
418
00:24:39,013 --> 00:24:40,812
THIS IS THE BELIEF
419
00:24:40,860 --> 00:24:45,064
HELD BY THEORETICAL PHYSICIST
CARLO ROVELLI.
420
00:24:45,177 --> 00:24:47,412
AS A STUDENT
IN HIS NATIVE ITALY,
421
00:24:47,472 --> 00:24:49,440
CARLO WAS ON THE BARRICADES,
422
00:24:49,494 --> 00:24:52,414
FIGHTING AGAINST
THE RESURGENT FASCIST MOVEMENT.
423
00:24:52,415 --> 00:24:54,783
I WAS YOUNG IN THE '70s,
424
00:24:54,847 --> 00:24:58,250
AND THERE WAS THE BIG DREAM
OF CHANGING THE WORLD.
425
00:24:58,341 --> 00:25:01,042
WE FAILED.
WE DIDN'T CHANGE THE WORLD.
426
00:25:01,115 --> 00:25:03,752
AND SO I THINK
I MOVED INTO SCIENCE
427
00:25:03,823 --> 00:25:06,658
BECAUSE I THOUGHT IT WAS ANOTHER
WAY OF CHANGING THE WORLD,
428
00:25:06,734 --> 00:25:09,001
AND PERHAPS I COULD BE
MORE SUCCESSFUL THERE.
429
00:25:09,062 --> 00:25:14,034
CARLO LEAVES THE CENTRE DE
PHYSIQUE TH?ORIQUE DE LUMINY,
430
00:25:14,167 --> 00:25:16,934
A THINK TANK
IN THE SOUTH OF FRANCE.
431
00:25:17,009 --> 00:25:20,611
BUT HE'S STILL BREAKING
THE RULES.
432
00:25:20,708 --> 00:25:24,611
AS THE LEADING VOICE OF
THE THEORY OF THERMAL TIME,
433
00:25:24,715 --> 00:25:28,385
HE IS RAISING THE BANNER
FOR A PARADIGM SHIFT
434
00:25:28,484 --> 00:25:30,351
IN FUNDAMENTAL PHYSICS.
435
00:25:30,401 --> 00:25:31,801
IN A NUTSHELL,
436
00:25:31,839 --> 00:25:36,543
THERMAL TIME PROPOSES
THAT TIME DOES NOT EXIST --
437
00:25:36,669 --> 00:25:39,229
AT LEAST NOT AT THE FUNDAMENTAL
LEVEL OF REALITY.
438
00:25:39,230 --> 00:25:41,932
THE IDEA THAT THERE'S
NO TIME ON THE FUNDAMENTAL LEVEL
439
00:25:42,005 --> 00:25:43,405
IS NOT SO COMPLICATED AFTER ALL.
440
00:25:43,443 --> 00:25:45,211
LET ME GIVE YOU AN EXAMPLE.
441
00:25:45,259 --> 00:25:47,493
IMAGINE THAT YOU DESCRIBE
SOMETHING HAPPENING IN TIME,
442
00:25:47,553 --> 00:25:49,920
LIKE THIS IS OSCILLATING
IN TIME.
443
00:25:49,984 --> 00:25:50,984
WHAT DO WE MEAN?
444
00:25:51,012 --> 00:25:52,413
WE MEAN THAT THERE IS SOMETHING
445
00:25:52,451 --> 00:25:53,918
THAT MOVES WITH RESPECT TO TIME.
446
00:25:53,958 --> 00:25:55,092
BUT WHAT IS TIME?
447
00:25:55,123 --> 00:25:57,857
TIME IS THE POSITION
OF THE HAND.
448
00:25:57,931 --> 00:26:00,333
SO WHAT WE
ARE REALLY OBSERVING HERE,
449
00:26:00,398 --> 00:26:02,767
WHAT WE'RE REALLY DOING HERE
IS COMPARING THIS MOVEMENT
450
00:26:02,777 --> 00:26:05,045
WITH THE MOVEMENT
OF THE HANDS OF THE CLOCK.
451
00:26:05,106 --> 00:26:08,109
SO WE DESCRIBE HOW
THE HAND'S CHANGING TIME,
452
00:26:08,190 --> 00:26:11,259
BUT WHAT WE REALLY SEE
IS JUST HOW THIS ANGLE
453
00:26:11,342 --> 00:26:13,508
CHANGES WITH RESPECT
TO THIS ANGLE.
454
00:26:13,566 --> 00:26:16,637
SO, DO WITHOUT TIME MEANS
JUST TO DESCRIBE THE WORLD
455
00:26:16,720 --> 00:26:19,622
IN TERMS OF THE WAY
THE VARIOUS VARIABLES CHANGE
456
00:26:19,700 --> 00:26:21,301
WITH RESPECT TO ONE ANOTHER
457
00:26:21,344 --> 00:26:25,079
WITHOUT EVER HAVING TO BRINGING
THIS UNOBSERVABLE TIME
458
00:26:25,180 --> 00:26:26,715
INTO THE PICTURE.
459
00:26:28,469 --> 00:26:32,840
ISAAC NEWTON INTRODUCED THE IDEA
OF A VARIABLE, "T" FOR "TIME,"
460
00:26:32,957 --> 00:26:37,227
TO DESCRIBE HOW OBJECTS MOVE.
461
00:26:37,341 --> 00:26:39,943
BUT QUANTUM PHYSICS
TREATS TIME DIFFERENTLY
462
00:26:40,013 --> 00:26:42,514
THAN NEWTON'S CLASSICAL SYSTEM.
463
00:26:43,466 --> 00:26:45,900
IN FACT, AT THE PLANCK SCALE,
464
00:26:45,965 --> 00:26:48,667
THE SMALLEST UNIT
OF THE PHYSICAL WORLD,
465
00:26:48,740 --> 00:26:52,576
TIME VARIABLES
SIMPLY DON'T WORK.
466
00:26:52,679 --> 00:26:55,915
CARLO THINKS THE ONLY WAY TO
RESOLVE THIS CONTRADICTION
467
00:26:56,002 --> 00:27:00,705
IS TO GO BACK BEFORE NEWTON
AND GET RID OF THE VARIABLE "T."
468
00:27:00,831 --> 00:27:05,002
HE HAS COMPLETELY REFORMULATED
QUANTUM THEORY
469
00:27:05,113 --> 00:27:07,346
WITHOUT THE USE OF TIME.
470
00:27:07,407 --> 00:27:10,877
BUT THAT'S JUST THE BEGINNING.
471
00:27:10,970 --> 00:27:13,772
THE INTERESTING PART
IS ACTUALLY THE SECOND PART
472
00:27:13,847 --> 00:27:15,516
BECAUSE IF WE ACCEPT THE IDEA
473
00:27:15,562 --> 00:27:18,229
THAT THERE'S NO TIME
ON THE FUNDAMENTAL LEVEL,
474
00:27:18,300 --> 00:27:20,469
NEVERTHELESS
WE DO EXPERIENCE TIME.
475
00:27:20,528 --> 00:27:23,060
TIME PASSES FOR US, RIGHT?
WE LIVE IN TIME.
476
00:27:23,128 --> 00:27:26,900
SO WHERE DOES
THIS TIME EXPERIENCE COME FROM?
477
00:27:30,324 --> 00:27:34,495
THE ANSWER,
CARLO THINKS, IS HEAT.
478
00:27:34,607 --> 00:27:36,840
WHEN YOU ADD HEAT TO MATTER,
479
00:27:36,900 --> 00:27:40,370
IRREVERSIBLE PROCESSES
BEGIN TO TAKE PLACE,
480
00:27:40,464 --> 00:27:43,298
EVENTS THAT CAN'T BE UNDONE.
481
00:27:43,374 --> 00:27:47,278
THINGS BEGIN TO CHANGE IN TIME.
482
00:27:47,382 --> 00:27:51,651
SO, EVERY TIME THERE IS SOME
LACK OF REVERSIBILITY IN TIME,
483
00:27:51,766 --> 00:27:52,867
THERE'S HEAT.
484
00:27:52,897 --> 00:27:55,465
SO TIME IS TIED TO HEAT,
485
00:27:55,534 --> 00:27:59,070
AND I THINK THAT THE KEY IDEA IS
NOT THAT HEAT COMES FROM TIME,
486
00:27:59,165 --> 00:28:01,067
BUT IS THAT TIME
COMES FROM HEAT.
487
00:28:01,119 --> 00:28:02,685
AND HEAT IS THERMODYNAMICS,
488
00:28:02,727 --> 00:28:07,364
AND WE HAVE UNDERSTOOD THAT
THERMODYNAMIC IS STATISTICS.
489
00:28:07,488 --> 00:28:10,623
SO TIME IS TIED TO STATISTICS.
490
00:28:10,708 --> 00:28:13,277
WE DON'T KNOW
THE FINE DETAILS OF NATURE.
491
00:28:13,346 --> 00:28:16,514
WE ONLY UNDERSTAND THE AVERAGE.
492
00:28:16,599 --> 00:28:22,270
WE HAVE ONLY
A STATISTICAL KNOWLEDGE.
493
00:28:23,359 --> 00:28:26,928
SAY CARLO HAS AN OVEN.
494
00:28:27,023 --> 00:28:30,661
TO MEASURE ALL THE QUANTUM
INTERACTIONS INSIDE THE OVEN,
495
00:28:30,759 --> 00:28:33,727
HE WOULD NEED TO MAKE
BILLIONS OF MEASUREMENTS.
496
00:28:33,807 --> 00:28:36,842
BUT NO ONE CAN DO THAT.
497
00:28:36,923 --> 00:28:37,891
SO, INSTEAD, HE SAYS,
498
00:28:37,918 --> 00:28:38,884
AAH!
499
00:28:38,911 --> 00:28:43,213
"THIS OVEN IS 450 DEGREES."
500
00:28:41,731 --> 00:28:45,000
TEMPERATURE IS AN AVERAGE
OF THE ENERGIES
501
00:28:45,088 --> 00:28:47,391
IN THE COUNTLESS PARTICLES
IN A SYSTEM.
502
00:28:47,453 --> 00:28:49,886
IT'S WHAT WE GET
WHEN WE GIVE UP DESCRIBING
503
00:28:49,952 --> 00:28:52,154
WHAT'S HAPPENING
IN THE QUANTUM WORLD,
504
00:28:52,213 --> 00:28:53,749
AND, CARLO SAYS, SO IS TIME.
505
00:28:53,791 --> 00:28:56,259
IF WE COULD SEE
ALL THE DETAILS OF THE WORLD,
506
00:28:56,325 --> 00:28:58,460
WE WOULD SEE
A TIMELESS WORLD IN SOME SENSE.
507
00:28:58,518 --> 00:29:01,887
WE WOULDN'T SEE THIS THING
THAT WE FEEL AS TIME.
508
00:29:05,265 --> 00:29:07,968
TO CARLO,
509
00:29:09,418 --> 00:29:13,487
TIME IS JUST A STATEMENT
OF LIMITED INFORMATION.
510
00:29:13,596 --> 00:29:17,500
THE FUNDAMENTAL LEVEL
OF THE UNIVERSE IS TIMELESS.
511
00:29:17,605 --> 00:29:19,872
BUT AT LARGER LEVELS OF REALITY,
512
00:29:19,933 --> 00:29:22,902
WHEN THE INTERACTIONS
OF MATTER AND HEAT
513
00:29:22,982 --> 00:29:25,116
BEGIN TO HAVE VISIBLE EFFECTS,
514
00:29:25,174 --> 00:29:28,416
THE THING
WE CALL "TIME" IS BORN.
515
00:29:28,417 --> 00:29:30,952
TIME BEGAN WHEN SOME SYSTEM,
516
00:29:31,020 --> 00:29:33,689
INSTEAD OF INTERACTING
JUST WITH ITS NEIGHBOR,
517
00:29:33,761 --> 00:29:36,562
INTERACTED WITH
A BIG SET OF SYSTEMS.
518
00:29:36,638 --> 00:29:38,739
SO TIME BEGAN WHEN SOME SYSTEM
519
00:29:38,795 --> 00:29:41,463
STARTED HAVING PARTIAL
INFORMATION,
520
00:29:41,535 --> 00:29:43,904
NOT COMPLETE INFORMATION
ABOUT ITS SURROUNDING.
521
00:29:43,968 --> 00:29:48,371
TIME BEGIN WITH OUR IGNORANCE
AND GROWS WITH OUR IGNORANCE.
522
00:29:48,489 --> 00:29:50,991
IT'S A RADICAL VIEW
OF THE UNIVERSE,
523
00:29:51,058 --> 00:29:56,095
BUT CARLO HAS NEVER BEEN AFRAID
TO CHALLENGE THE STATUS QUO.
524
00:29:56,230 --> 00:29:58,931
IS CARLO CORRECT?
525
00:29:59,004 --> 00:30:02,072
IS TIME REALLY
JUST OUR FAILURE TO COMPREHEND
526
00:30:02,154 --> 00:30:04,856
THE DISPERSION OF HEAT?
527
00:30:04,929 --> 00:30:06,966
THIS WOMAN SAYS
THERE IS ANOTHER POSSIBILITY.
528
00:30:07,227 --> 00:30:08,311
TIME IS REAL.
529
00:30:10,000 --> 00:30:13,004
BUT IT IS BORN AND REBORN
530
00:30:13,085 --> 00:30:15,953
A TRILLION, TRILLION TIMES
A SECOND.
531
00:30:21,141 --> 00:30:23,710
WHEN I MOVE FROM PLACE TO PLACE,
532
00:30:23,779 --> 00:30:28,248
MY SENSES TELL ME IT HAPPENS
IN ONE CONTINUOUS SWEEP.
533
00:30:28,368 --> 00:30:31,973
BUT ACCORDING TO QUANTUM
MECHANICS, ANY MOVEMENT...
534
00:30:33,541 --> 00:30:36,344
IS ACTUALLY A SERIES
OF MICROSCOPIC JITTERS
535
00:30:36,419 --> 00:30:38,218
THROUGH SPACE.
536
00:30:38,267 --> 00:30:39,500
HUH?
537
00:30:39,534 --> 00:30:41,270
NO ONE HAS YET WORKED OUT
538
00:30:41,317 --> 00:30:45,120
HOW TO APPLY THE THEORY
OF QUANTUM MECHANICS TO TIME,
539
00:30:45,222 --> 00:30:49,158
BUT SOME SCIENTISTS
ARE GETTING VERY CLOSE.
540
00:30:49,263 --> 00:30:55,702
IF THEY SUCCEED, WE WILL HAVE TO
ACCEPT A STRANGE, NEW IDEA --
541
00:30:55,874 --> 00:30:59,175
EVERY MINUTE FRACTION
OF A SECOND,
542
00:30:59,264 --> 00:31:07,004
TIME BURSTS INTO EXISTENCE
OVER AND OVER.
543
00:31:08,592 --> 00:31:13,740
LIKE ALL OF US, FAY DOWKER
EXPERIENCES A FLOW OF TIME.
544
00:31:13,741 --> 00:31:15,542
SHE WAS A GIRL...
545
00:31:15,591 --> 00:31:17,692
THEN A UNIVERSITY STUDENT...
546
00:31:17,749 --> 00:31:21,119
AND NOW SHE'S A PHYSICIST
AT LONDON'S IMPERIAL COLLEGE.
547
00:31:21,312 --> 00:31:23,947
NOTHING IS MORE FUNDAMENTAL
TO OUR EXPERIENCES
548
00:31:24,018 --> 00:31:26,253
THAN THAT WE HAVE
THOSE EXPERIENCES IN TIME.
549
00:31:26,313 --> 00:31:28,547
WE ARE AWARE OF TIME PASSING.
550
00:31:28,607 --> 00:31:31,942
TIME SEEMS TO FLOW.
551
00:31:32,032 --> 00:31:35,034
WE CAN HARDLY MAKE SENSE OF OUR
LIVES EXCEPT IN THE CONTEXT
552
00:31:35,115 --> 00:31:37,950
OF SOME FIXED PAST OF EVENTS
THAT HAVE ALREADY HAPPENED
553
00:31:38,026 --> 00:31:40,061
AND THAT CAN NEVER BE CHANGED
554
00:31:40,116 --> 00:31:42,317
AND SOME OPEN FUTURE OF EVENTS
555
00:31:42,376 --> 00:31:45,346
THAT ARE FREE
AND HAVEN'T HAPPENED YET
556
00:31:45,426 --> 00:31:48,127
AND SOME MYSTERIOUS
AND ELUSIVE MOMENT OF NOW
557
00:31:48,200 --> 00:31:51,004
THAT APPEARS
TO SEPARATE THE TWO.
558
00:31:52,960 --> 00:31:55,929
THIS IDEA SEEMS OBVIOUS.
559
00:31:56,009 --> 00:32:00,712
BUT, ACTUALLY, IT GOES AGAINST
OUR BEST SCIENTIFIC THEORY
560
00:32:00,838 --> 00:32:02,807
OF HOW THE UNIVERSE WORKS.
561
00:32:02,860 --> 00:32:04,895
THE THEORY OF RELATIVITY
562
00:32:04,950 --> 00:32:09,053
TELLS US SPACE AND TIME
ARE INEXTRICABLY JOINED.
563
00:32:09,163 --> 00:32:13,134
ALL TIME THAT WILL EXIST
ALREADY EXISTS
564
00:32:13,241 --> 00:32:16,274
IN A BLOCK WE CALL "SPACE-TIME."
565
00:32:16,355 --> 00:32:18,824
AS WE PASS FROM BIRTH TO DEATH,
566
00:32:18,891 --> 00:32:21,959
WE GLIMPSE
OUR OWN INDIVIDUAL TRAILS
567
00:32:22,041 --> 00:32:25,577
THROUGH THIS
FROZEN SPACE-TIME LANDSCAPE.
568
00:32:25,672 --> 00:32:30,009
BUT FAY BELIEVES THE UNIVERSE
IS NOT A FROZEN BLOCK.
569
00:32:30,125 --> 00:32:32,092
IT IS A GROWING PILE
570
00:32:32,145 --> 00:32:35,049
MADE OF QUANTUM GRAINS
OF SPACE AND TIME.
571
00:32:35,641 --> 00:32:39,978
SPACE-TIME SEEMS SMOOTH
AND CONTINUOUS TO US,
572
00:32:40,094 --> 00:32:42,029
BUT THAT'S JUST BECAUSE
WE'RE VERY LARGE
573
00:32:42,081 --> 00:32:44,515
AND WE SEE THINGS
AT LARGE SCALES.
574
00:32:44,581 --> 00:32:48,917
SO, IF WE IMAGINE
THAT A SOLID CUBE OF SOMETHING,
575
00:32:49,033 --> 00:32:50,668
SAY A SUGAR CUBE,
576
00:32:50,713 --> 00:32:53,848
REPRESENTS A PIECE
OF SPACE-TIME,
577
00:32:53,932 --> 00:32:56,734
THEN FROM FAR AWAY,
THAT LOOKS SOLID.
578
00:32:56,809 --> 00:32:58,443
IT LOOKS LIKE A CHUNK.
579
00:32:58,488 --> 00:33:00,489
BUT WE KNOW
THAT IF YOU ZOOM IN ON IT
580
00:33:00,543 --> 00:33:02,945
AND LOOK AT
ITS MORE FUNDAMENTAL STRUCTURE,
581
00:33:03,010 --> 00:33:05,144
WE SEE THAT IT BREAKS UP
INTO GRAINS.
582
00:33:05,201 --> 00:33:09,071
THE IDEA WITH A GRANULAR MODEL
OF SPACE-TIME IS SIMILAR.
583
00:33:09,175 --> 00:33:13,812
AT FUNDAMENTAL, TINY SCALES,
IT'S GRAINY AND PARTICULATE.
584
00:33:13,936 --> 00:33:16,303
AT LARGE SCALES, IT APPEARS
SMOOTH AND CONTINUOUS.
585
00:33:16,367 --> 00:33:17,935
WE DON'T NOTICE
THAT GRANULARITY.
586
00:33:17,978 --> 00:33:23,149
JUST HOW SMALL
IS A GRAIN OF SPACE-TIME?
587
00:33:23,287 --> 00:33:26,456
INCONCEIVABLY SMALL.
588
00:33:26,541 --> 00:33:30,177
ROUGHLY A MILLION, TRILLION,
TRILLION, TRILLIONTH
589
00:33:30,275 --> 00:33:31,643
OF A SECOND.
590
00:33:31,680 --> 00:33:34,748
THIS IS WHAT PHYSICISTS BELIEVE
591
00:33:34,831 --> 00:33:38,167
IS THE SMALLEST POSSIBLE UNIT
OF MEASUREMENT.
592
00:33:38,256 --> 00:33:41,725
FAY THINKS SPACE-TIME IS BUILT
593
00:33:41,818 --> 00:33:46,656
FROM A PRODIGIOUS STACK
OF THESE IMPOSSIBLY TINY GRAINS,
594
00:33:46,786 --> 00:33:50,520
WHICH SHE CALLS
"SPACE-TIME ATOMS."
595
00:33:50,620 --> 00:33:53,723
THIS MARRIES TOGETHER
TWO CONCEPTS --
596
00:33:53,806 --> 00:33:57,642
THAT SPACE-TIME
IS FUNDAMENTALLY ATOMIC
597
00:33:57,745 --> 00:34:01,182
OR BITTY OR GRANULAR
AT VERY TINY SCALES
598
00:34:01,274 --> 00:34:04,008
WITH THE NOTION OF CAUSALITY,
599
00:34:04,082 --> 00:34:08,952
THE FACT
THAT CAUSE MUST PRECEDE EFFECT.
600
00:34:09,082 --> 00:34:11,385
SO, FOR EXAMPLE,
IF I HEAR A LOUD NOISE...
601
00:34:11,756 --> 00:34:13,891
...THEN THAT WILL STARTLE ME,
602
00:34:13,949 --> 00:34:17,250
AND I MIGHT DROP
MY CUP OF COFFEE.
603
00:34:17,339 --> 00:34:20,141
SO THE CAUSE WAS THE LOUD NOISE.
604
00:34:20,216 --> 00:34:25,653
THE EFFECT WAS THE DROPPING
OF MY CUP OF COFFEE.
605
00:34:25,799 --> 00:34:30,371
IF, AS RELATIVITY INSISTS,
606
00:34:30,493 --> 00:34:35,162
ALL OF SPACE AND TIME
ALREADY EXIST,
607
00:34:35,287 --> 00:34:39,157
THE COFFEE CUP WILL ALWAYS FALL,
IS ALWAYS FALLING,
608
00:34:39,261 --> 00:34:41,530
HAS ALWAYS FALLEN.
609
00:34:41,591 --> 00:34:44,157
BUT IN FAY'S VIEW,
610
00:34:44,226 --> 00:34:47,196
THE UNIVERSE IS A SET OF EVENTS
THAT IS FOREVER GROWING.
611
00:34:47,347 --> 00:34:51,083
WHEN WE OBSERVE THESE
CONNECTED SEQUENCES OF EVENTS,
612
00:34:51,183 --> 00:34:53,216
WHAT SHE CALLS A CAUSAL SET,
613
00:34:53,271 --> 00:34:56,807
WE PERCEIVE
THAT TIME IS PASSING.
614
00:34:56,902 --> 00:34:59,504
A CAUSAL SET CAN GROW
615
00:34:59,574 --> 00:35:03,578
BY THE ACCUMULATION
OF NEW SPACE-TIME ATOMS.
616
00:35:03,685 --> 00:35:07,588
AND THIS BIRTH
OF NEW SPACE-TIME ATOMS
617
00:35:07,693 --> 00:35:12,495
COULD BE THE PASSAGE
OF TIME AS WE KNOW IT.
618
00:35:12,624 --> 00:35:15,793
WHAT WE EXPERIENCE
AS THE PRESENT
619
00:35:15,878 --> 00:35:19,080
IS THE BIRTH
OF THESE NEW SPACE-TIME ATOMS.
620
00:35:19,166 --> 00:35:21,801
THE OLD ATOMS DON'T DIE.
621
00:35:21,872 --> 00:35:26,009
THEY PILE UP INTO
THE THING WE CALL "THE PAST."
622
00:35:26,120 --> 00:35:28,387
THE FUTURE HAS YET TO BE BORN.
623
00:35:28,448 --> 00:35:33,186
ONCE A SPACE-TIME ATOM
IS BORN AND EXISTS,
624
00:35:33,313 --> 00:35:36,116
IT WILL THEN FORM PART
OF THE PAST.
625
00:35:36,191 --> 00:35:37,290
SO, IN THAT SENSE,
626
00:35:37,320 --> 00:35:39,121
IT ALSO REALIZES OUR SENSE
627
00:35:39,170 --> 00:35:40,805
THAT THE PAST IS FIXED,
628
00:35:40,850 --> 00:35:45,121
THAT THE PAST HAS HAPPENED,
AND THAT IT CANNOT BE CHANGED.
629
00:35:45,439 --> 00:35:49,110
TIME MAY NOT BE
A CONTINUOUS RIVER,
630
00:35:49,209 --> 00:35:52,643
BUT RATHER
AN ENDLESS RAIN OF EVENTS.
631
00:35:52,735 --> 00:35:56,205
SO, WHICH CONCEPT
OF TIME IS CORRECT?
632
00:35:56,298 --> 00:35:59,134
ARE WE GETTING CLOSER
TO THE ORIGIN OF TIME?
633
00:35:59,210 --> 00:36:02,111
WE MAY SOON KNOW.
634
00:36:02,189 --> 00:36:07,826
IN THIS LABORATORY, RESEARCHERS
ARE WORKING ON A NEW EXPERIMENT
635
00:36:07,977 --> 00:36:09,847
THAT COULD FOREVER CHANGE
636
00:36:09,898 --> 00:36:12,734
OUR UNDERSTANDING OF TIME
AND THE UNIVERSE.
637
00:36:18,289 --> 00:36:22,625
TIME MAY HAVE BEGUN
AT THE BIG BANG.
638
00:36:22,741 --> 00:36:26,144
IT MAY HAVE ALWAYS BEEN FLOWING.
639
00:36:26,235 --> 00:36:32,073
OR IT COULD BE BORN
TRILLIONS OF TIMES EVERY SECOND.
640
00:36:32,229 --> 00:36:35,898
THIS DEBATE
COULD GO ON FOR DECADES.
641
00:36:35,997 --> 00:36:38,898
OR IT COULD END ANY DAY NOW.
642
00:36:38,976 --> 00:36:41,979
BECAUSE WE MAY
FINALLY HAVE AN EXPERIMENT
643
00:36:42,059 --> 00:36:46,362
THAT REVEALS
THE TRUE NATURE OF TIME.
644
00:36:46,478 --> 00:36:53,284
AT THE BERKELEY CAMPUS
OF THE UNIVERSITY OF CALIFORNIA,
645
00:36:53,465 --> 00:36:57,268
PROFESSOR HARTMUT HAEFFNER
IS BUILDING A TIME RING --
646
00:36:57,370 --> 00:37:02,074
AN OBJECT
THAT WILL ROTATE LIKE THIS DISK.
647
00:37:02,200 --> 00:37:04,300
BUT WHILE THIS METAL RING
648
00:37:04,357 --> 00:37:07,827
IS LEVITATED USING
ELECTROMAGNETIC FORCE,
649
00:37:07,920 --> 00:37:12,492
A TIME RING WILL BE DRIVEN
BY A JITTER IN TIME.
650
00:37:13,812 --> 00:37:16,313
IF IT WORKS,
651
00:37:16,380 --> 00:37:19,584
THIS EXPERIMENT WILL PROVE
A CONTROVERSIAL THEORY --
652
00:37:19,670 --> 00:37:24,138
THE QUANTUM FLUCTUATIONS
THAT HAVE BEEN OBSERVED IN SPACE
653
00:37:24,258 --> 00:37:26,360
ALSO EXIST IN TIME.
654
00:37:26,692 --> 00:37:28,894
WE PHYSICISTS LIKE SYMMETRIES,
655
00:37:28,953 --> 00:37:32,554
AND ONE SYMMETRY
IS LIKE SPACE AND TIME.
656
00:37:32,651 --> 00:37:35,420
WE WOULD LIKE TO TREAT THEM
ON THE SAME FOOTING,
657
00:37:35,494 --> 00:37:37,828
SO WHATEVER WE OBSERVE IN SPACE,
658
00:37:37,891 --> 00:37:40,759
WE THINK
WE SHOULD ALSO SEE IN TIME,
659
00:37:40,836 --> 00:37:44,272
AND THIS WOULD ACTUALLY SIMPLIFY
THE DESCRIPTION OF THE UNIVERSE
660
00:37:44,365 --> 00:37:45,732
OR MAKE IT MORE ELEGANT.
661
00:37:46,246 --> 00:37:51,384
NANOTECHNOLOGIST
TONGCANG LI, ALSO AT BERKELEY,
662
00:37:51,521 --> 00:37:54,223
DEVISED THE TIME-RING
EXPERIMENT.
663
00:37:54,296 --> 00:37:55,929
HE APPROACHED HARTMUT,
664
00:37:55,974 --> 00:37:59,645
AN EXPERT IN TRAPPING
AND STUDYING ATOMIC PARTICLES.
665
00:37:59,743 --> 00:38:02,577
BUT HARTMUT HAD HIS DOUBTS.
666
00:38:02,653 --> 00:38:04,888
IN THE BEGINNING,
I MEAN, I WAS THINKING,
667
00:38:04,949 --> 00:38:06,049
"I MEAN, THEY ARE CRAZY.
668
00:38:06,079 --> 00:38:08,147
I MEAN,
THIS IS A RIDICULOUS IDEA,"
669
00:38:08,203 --> 00:38:12,507
AND THEN WE START TO TALKING,
AND I REALIZED, "OH, WAIT.
670
00:38:12,622 --> 00:38:14,655
"THIS IS REALLY WEIRD,
BUT THEY ARE RIGHT.
671
00:38:14,710 --> 00:38:16,111
THIS IS THE WAY IT SHOULD BE."
672
00:38:16,655 --> 00:38:18,000
ON THIS ELECTRODE,
673
00:38:18,000 --> 00:38:21,334
INSIDE A SPACE THE WIDTH
OF A HUMAN HAIR,
674
00:38:21,424 --> 00:38:26,262
HARTMUT AND HIS TEAM WILL CREATE
A PERFECTLY STATIC LANDSCAPE --
675
00:38:26,391 --> 00:38:30,194
A LANDSCAPE ISOLATED
FROM OUTSIDE ENERGY.
676
00:38:30,296 --> 00:38:33,632
TO FURTHER REDUCE ENERGY
IN THE SYSTEM,
677
00:38:33,722 --> 00:38:36,690
HE MUST TRAP
AND COOL CALCIUM IONS
678
00:38:36,770 --> 00:38:41,575
DOWN TO A FEW BILLIONTHS OF
A DEGREE ABOVE ABSOLUTE ZERO --
679
00:38:41,703 --> 00:38:46,240
COLDER THAN ANYTHING
HAS EVER BEEN COOLED BEFORE.
680
00:38:46,362 --> 00:38:51,064
THIS WILL TAKE THE IONS
DOWN TO THEIR GROUND STATE --
681
00:38:51,189 --> 00:38:53,206
THE STATE
OF MINIMUM POSSIBLE ENERGY.
682
00:38:53,207 --> 00:38:58,878
ONLY THEN CAN THE EFFECTS
OF SPACE BE SEPARATED FROM TIME.
683
00:38:59,029 --> 00:39:02,765
IMAGINE THESE BALL
BEARINGS ARE CALCIUM IONS
684
00:39:02,865 --> 00:39:05,734
AND WE'RE GOING TO INJECT 100
OF THESE CALCIUM IONS
685
00:39:05,812 --> 00:39:07,713
INTO OUR VACUUM CHAMBER.
686
00:39:07,764 --> 00:39:09,464
SO, AT NORMAL TEMPERATURES,
687
00:39:09,510 --> 00:39:13,547
THESE IONS MOVE AROUND RAPIDLY
IN RANDOM DIRECTIONS,
688
00:39:13,655 --> 00:39:17,456
BUT WHEN WE COOL THEM, THEY FORM
THIS RING AND THEY SLOW DOWN,
689
00:39:17,558 --> 00:39:19,726
AND YOU WOULD EXPECT
THAT AT SOME POINT,
690
00:39:19,785 --> 00:39:21,353
THIS RING STOPS MOVING.
691
00:39:21,396 --> 00:39:22,730
IT WOULDN'T ROTATE,
692
00:39:22,766 --> 00:39:25,868
BUT IF THIS THEORY IS CORRECT,
693
00:39:25,951 --> 00:39:29,589
THAT RING SHOULD MOVE,
ROTATE, SPIN.
694
00:39:31,432 --> 00:39:34,701
AN OBJECT
AT GROUND STATE SHOULDN'T MOVE,
695
00:39:34,789 --> 00:39:39,694
BECAUSE IT NEITHER CONSUMES
NOR PRODUCES ENERGY.
696
00:39:39,825 --> 00:39:45,796
BUT QUANTUM MECHANICS TELLS US
ZERO DOES NOT MEAN ZERO.
697
00:39:45,956 --> 00:39:50,626
EVEN AT GROUND STATE, THERE WILL
STILL BE QUANTUM FLUCTUATIONS.
698
00:39:50,751 --> 00:39:53,665
IN QUANTUM MECHANICS, THERE'S
ALWAYS THIS FINITE JITTER MOTION
699
00:39:53,666 --> 00:39:54,966
IN THE GROUND STATE.
700
00:39:55,001 --> 00:39:56,402
THINGS WILL STILL MOVE,
701
00:39:56,441 --> 00:39:58,909
BUT THEY WILL MOVE
IN AN UNDIRECTED WAY.
702
00:39:58,975 --> 00:40:00,710
WHAT WE ARE AFTER IS SOMETHING
703
00:40:00,757 --> 00:40:04,993
WHERE THERE IS STILL MOTION
IN A PARTICULAR DIRECTION.
704
00:40:05,107 --> 00:40:08,244
IT WOULD BE DIFFERENT
IN THE SENSE THAT IT'S DIRECTED.
705
00:40:10,827 --> 00:40:14,129
FREEZING THE IONS
WILL ALLOW THEM
706
00:40:14,217 --> 00:40:17,854
TO MAKE ONLY TINY,
RANDOM MOVEMENTS IN SPACE --
707
00:40:17,952 --> 00:40:20,619
TOO SMALL TO MAKE THE RING MOVE.
708
00:40:20,691 --> 00:40:25,629
BUT IF THE ION RING
BEGINS TO TURN ANYWAY,
709
00:40:25,761 --> 00:40:30,198
IT WILL MEAN THERE HAS BEEN
A FLUCTUATION IN TIME.
710
00:40:30,317 --> 00:40:33,618
FROM THE THEORY PERSPECTIVE,
IT'S NOT AT ALL CLEAR
711
00:40:33,706 --> 00:40:35,776
WHAT IS GOING TO HAPPEN
AT THESE LOW TEMPERATURES.
712
00:40:35,777 --> 00:40:39,014
THERE ARE PEOPLE WHO SAY
THAT THIS RING SHOULD MOVE,
713
00:40:39,101 --> 00:40:40,833
AND OTHERS SAY IT SHOULDN'T.
714
00:40:40,880 --> 00:40:43,716
IF THE TIME RING WORKS,
715
00:40:43,792 --> 00:40:46,594
THEN BOTH SPACE
AND TIME FLUCTUATE.
716
00:40:46,670 --> 00:40:51,006
THAT MIGHT SUPPORT FAY DOWKER'S
THEORY THAT SPACE-TIME
717
00:40:51,122 --> 00:40:55,459
IS CONSTANTLY GENERATING ITSELF
IN QUANTUM DIPS.
718
00:40:55,575 --> 00:40:58,911
AT THE VERY LEAST,
IT WILL DEMONSTRATE
719
00:40:59,001 --> 00:41:02,102
THAT SPACE AND TIME
ARE INEXTRICABLY LINKED
720
00:41:02,185 --> 00:41:03,919
IN THE QUANTUM REALM.
721
00:41:03,966 --> 00:41:07,497
SO, WE HAVE THESE
QUANTUM FLUCTUATIONS IN SPACE,
722
00:41:07,498 --> 00:41:09,300
BUT TIME WE TREAT AS SOMETHING
723
00:41:09,349 --> 00:41:12,083
WHICH YOU CAN KNOW
VERY PRECISELY.
724
00:41:12,157 --> 00:41:15,626
WELL, ACTUALLY, WHAT I WOULD BE
FEELING MUCH MORE HAPPY WITH
725
00:41:15,719 --> 00:41:18,555
IS IF QUANTUM MECHANICS
WOULD ALSO ASSUME
726
00:41:18,631 --> 00:41:20,932
THAT TIME IS FUZZY,
SO TO SPEAK,
727
00:41:20,994 --> 00:41:26,198
THAT YOU CAN'T TELL WHAT TIME IT
IS EXACTLY, ONLY APPROXIMATELY,
728
00:41:26,337 --> 00:41:28,305
THAT YOU HAVE
FLUCTUATIONS OF TIME.
729
00:41:28,359 --> 00:41:29,959
AND I'VE NEVER WORKED
WITH SOMETHING
730
00:41:30,002 --> 00:41:31,670
WHERE TIME FLUCTUATES, SO...
731
00:41:33,393 --> 00:41:36,129
WHEN I SEE IT, MAYBE THEN IT
BECOMES NATURAL TO ME, TOO.
732
00:41:40,555 --> 00:41:44,759
IF WE FIND THE ORIGINS OF TIME,
733
00:41:44,871 --> 00:41:49,609
WE WILL ANSWER ONE OF
THE DEEPEST RIDDLES OF CREATION.
734
00:41:49,736 --> 00:41:51,137
BUT WE MIGHT ALSO LEARN
735
00:41:51,175 --> 00:41:55,745
THAT TIME IS MEANINGLESS
TO THE UNIVERSE --
736
00:41:55,868 --> 00:41:58,637
TIME ONLY MATTERS TO US
737
00:41:58,711 --> 00:42:03,980
BECAUSE IT ANCHORS US BETWEEN
OUR MEMORIES OF THE PAST...
738
00:42:04,121 --> 00:42:05,957
AND THE MYSTERY OF THE FUTURE.
739
00:42:06,007 --> 00:42:10,557
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