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1
00:00:02,133 --> 00:00:05,367
Freeman: WE ALL FLOAT
ALONG THE RIVER OF TIME.
2
00:00:05,367 --> 00:00:08,133
BUT DOES THAT RIVER
HAVE A SOURCE?
3
00:00:09,400 --> 00:00:11,400
HOW WAS TIME UNLEASHED?
4
00:00:11,400 --> 00:00:16,667
SOME BELIEVE TIME
FLOWS SMOOTHLY AND ETERNALLY.
5
00:00:16,667 --> 00:00:20,300
OTHERS SAY
IT DOESN'T FLOW AT ALL --
6
00:00:20,300 --> 00:00:23,667
IT POPS INTO EXISTENCE
EVERY FRACTION OF A SECOND.
7
00:00:25,733 --> 00:00:28,967
THE FINEST MINDS
IN PHYSICS CAN'T AGREE.
8
00:00:28,967 --> 00:00:32,033
BUT NEW EXPERIMENTS
MAY HOLD THE ANSWER
9
00:00:32,033 --> 00:00:38,233
TO THE GREATEST UNSOLVED MYSTERY
IN THE HISTORY OF THE UNIVERSE.
10
00:00:38,233 --> 00:00:39,333
THE MYSTERY...
11
00:00:39,333 --> 00:00:43,133
OF WHEN TIME BEGAN.
12
00:00:46,867 --> 00:00:48,433
SPACE...
13
00:00:48,433 --> 00:00:49,800
TIME...
14
00:00:49,800 --> 00:00:51,333
LIFE ITSELF.
15
00:00:53,833 --> 00:00:59,333
THE SECRETS OF THE COSMOS
LIE THROUGH THE WORMHOLE.
16
00:00:59,333 --> 00:01:02,400
-- Captions by VITAC --
www.vitac.com
17
00:01:02,400 --> 00:01:05,433
CAPTIONS PAID FOR BY
DISCOVERY COMMUNICATIONS
18
00:01:12,200 --> 00:01:14,767
WHEN WERE YOU BORN?
19
00:01:14,767 --> 00:01:16,867
SOUNDS LIKE A SIMPLE QUESTION.
20
00:01:16,867 --> 00:01:20,133
YOU JUST SAY A CERTAIN YEAR,
A MONTH, AND DAY.
21
00:01:20,133 --> 00:01:23,733
BUT AROUND THE WORLD,
WE RECKON TIME DIFFERENTLY.
22
00:01:23,733 --> 00:01:26,833
IN SAUDI ARABIA,
IT'S THE 15th CENTURY.
23
00:01:26,833 --> 00:01:29,633
IN ISRAEL, IT'S THE 58th.
24
00:01:29,633 --> 00:01:33,433
AND WE LIVE IN
24 DIFFERENT TIME ZONES.
25
00:01:33,433 --> 00:01:37,433
WE ALL MEASURE TIME RELATIVE
TO SOME STARTING POINT --
26
00:01:37,433 --> 00:01:39,200
A POINT WE HAVE CHOSEN.
27
00:01:39,200 --> 00:01:42,567
BUT IF WE REALLY WANT TO KNOW
WHAT TIME IT IS,
28
00:01:42,567 --> 00:01:47,233
WE NEED TO KNOW WHEN THE COSMIC
CLOCK STARTED TO TICK.
29
00:01:47,233 --> 00:01:51,067
DID TIME BEGIN
WHEN THE UNIVERSE BEGAN?
30
00:01:51,067 --> 00:01:55,767
OR DID IT START SOME OTHER WAY?
31
00:01:55,767 --> 00:01:57,733
[ BIRDS CHIRPING ]
32
00:01:57,733 --> 00:02:00,200
ONCE, I WAS IN A BIKE RACE.
33
00:02:00,200 --> 00:02:04,067
I WANTED TO IMPRESS SOME FRIENDS
WITH MY TERRIFIC SPEED.
34
00:02:06,067 --> 00:02:10,300
SO I GAVE IT EVERYTHING I HAD.
35
00:02:10,300 --> 00:02:16,133
IT WAS A CLOSE RACE -- SO CLOSE,
I THOUGHT IT WAS A TIE.
36
00:02:16,133 --> 00:02:19,867
ONE KID SAID
MY OPPONENT WAS QUICKEST.
37
00:02:19,867 --> 00:02:22,933
BUT ANOTHER SAID I WAS FASTER.
38
00:02:22,933 --> 00:02:27,067
SO, WHOSE PERCEPTION OF TIME
WAS CORRECT?
39
00:02:27,067 --> 00:02:32,667
IN A WAY, WE WERE ALL RIGHT.
40
00:02:32,667 --> 00:02:36,667
TIME IS A MEASURE OF CHANGE.
41
00:02:36,667 --> 00:02:39,200
[ CLOCK TICKING ]
42
00:02:39,200 --> 00:02:42,333
BUT HOW DO
WE KNOW THINGS CHANGE?
43
00:02:42,333 --> 00:02:45,233
WE RELY ON WHAT
OUR SENSES TELL US,
44
00:02:45,233 --> 00:02:48,600
AND PRIMARILY,
WE RELY ON WHAT WE CAN SEE.
45
00:02:48,600 --> 00:02:51,667
WE RELY ON LIGHT.
46
00:02:51,667 --> 00:02:53,667
IN THE VACUUM OF SPACE,
47
00:02:53,667 --> 00:02:58,867
LIGHT TRAVELS AT A FIXED SPEED
OF 186,000 MILES PER SECOND.
48
00:02:58,867 --> 00:03:04,900
THIS IS ACCEPTED AS AN ABSOLUTE
TRUTH OF THE UNIVERSE.
49
00:03:04,900 --> 00:03:09,200
AND THAT,
SAYS COSMOLOGIST JANNA LEVIN,
50
00:03:09,200 --> 00:03:13,333
GIVES LIGHT A UNIQUE
RELATIONSHIP TO TIME.
51
00:03:13,333 --> 00:03:15,733
Levin: IT'S ACTUALLY
COMPLETELY REMARKABLE
52
00:03:15,733 --> 00:03:17,967
THAT THE SPEED OF LIGHT
IS AN ABSOLUTE.
53
00:03:17,967 --> 00:03:20,133
IT'S NEVER FASTER.
IT'S NEVER SLOWER.
54
00:03:20,133 --> 00:03:22,533
TO UNDERSTAND
THE RELATIVITY OF TIME,
55
00:03:22,533 --> 00:03:24,500
WE REALLY NEED
TO UNDERSTAND LIGHT,
56
00:03:24,500 --> 00:03:26,933
AND ONCE WE START THINKING ABOUT
THE NATURE OF LIGHT,
57
00:03:26,933 --> 00:03:30,233
ALL OF OUR FAMILIAR INTUITIONS
ARE TURNED ON THEIR HEADS.
58
00:03:30,233 --> 00:03:34,200
Freeman: IF THE SPEED OF LIGHT
IS CONSTANT,
59
00:03:34,200 --> 00:03:37,733
THEN TIME AND SPACE
MUST SHIFT AND DISTORT
60
00:03:37,733 --> 00:03:42,200
DEPENDING ON YOUR PARTICULAR
POINT OF VIEW.
61
00:03:42,200 --> 00:03:45,667
Levin: EINSTEIN HAD
THIS VERY PROFOUND INSIGHT
62
00:03:45,667 --> 00:03:48,667
WHEN HE STARTED TO THINK ABOUT
SOMETHING AS SIMPLE AS LIGHT,
63
00:03:48,667 --> 00:03:53,100
AND HE REALIZED THAT IF LIGHT
WAS GOING TO BE THE SAME
64
00:03:53,100 --> 00:03:55,500
FOR EVERYBODY IN THE UNIVERSE
65
00:03:55,500 --> 00:03:57,500
REGARDLESS OF HOW FAST
THEY WERE MOVING
66
00:03:57,500 --> 00:03:59,200
OR WHERE THEY WERE
IN THE UNIVERSE,
67
00:03:59,200 --> 00:04:01,133
THEN SPACE AND TIME
HAD TO BE DIFFERENT
68
00:04:01,133 --> 00:04:03,400
FOR DIFFERENT OBSERVERS.
69
00:04:03,400 --> 00:04:06,133
Freeman: THIS MEANS TIME
IS VERY PERSONAL.
70
00:04:06,133 --> 00:04:10,833
IT DEPENDS ON WHERE YOU ARE
AND HOW FAST YOU ARE MOVING.
71
00:04:10,833 --> 00:04:13,867
AND THE WAY YOU SEE
YOUR MOVEMENT THROUGH TIME
72
00:04:13,867 --> 00:04:18,233
MAY NOT BE THE WAY OTHERS
SEE YOUR MOVEMENT THROUGH TIME.
73
00:04:22,333 --> 00:04:26,100
SAY, FOR INSTANCE,
JANNA HAS A DOPPELGANGER
74
00:04:26,100 --> 00:04:29,400
THAT RIDES THE SUBWAYS
AND TAXIS OF NEW YORK.
75
00:04:29,400 --> 00:04:30,633
[ HORN HONKS ]
76
00:04:30,633 --> 00:04:34,400
IF JANNA'S DOPPELGANGER
GETS IN A CAB
77
00:04:34,400 --> 00:04:36,933
AND THAT CAB TRAVELS
AT INCREDIBLE SPEEDS...
78
00:04:36,933 --> 00:04:38,400
[ TIRES SQUEALING ]
79
00:04:40,233 --> 00:04:43,333
...TIME WILL FLOW DIFFERENTLY
FOR EACH WOMAN.
80
00:04:43,333 --> 00:04:46,767
Levin:
IF SHE FLIES PAST ME IN A TAXI,
81
00:04:46,767 --> 00:04:50,433
IT WILL APPEAR TO ME
THAT HER TIME IS RUNNING SLOWER.
82
00:04:50,433 --> 00:04:54,333
FROM MY DOPPELGANGER'S POINT OF
VIEW, THE STREET WITH ME ON IT,
83
00:04:54,333 --> 00:04:56,733
WE'RE FLYING PAST HER
IN THE OPPOSITE DIRECTION,
84
00:04:56,733 --> 00:04:58,900
AND AS FAR AS SHE'S CONCERNED,
HER TIME IS NORMAL.
85
00:04:58,900 --> 00:05:02,167
IT'S MY TIME
THAT'S RUNNING SLOW.
86
00:05:02,167 --> 00:05:06,700
Freeman:
TO UNDERSTAND WHY THIS HAPPENS,
87
00:05:06,700 --> 00:05:10,467
IMAGINE JANNA TURNS ON
A DOUBLE-SIDED LASER
88
00:05:10,467 --> 00:05:14,467
WHOSE PULSING BEAMS BOUNCE OFF
THE SIDEWALK BELOW HER
89
00:05:14,467 --> 00:05:16,367
AND THE BALCONY ABOVE HER HEAD.
90
00:05:16,367 --> 00:05:19,533
THE PULSES FORM A LIGHT CLOCK.
91
00:05:19,533 --> 00:05:23,400
EACH BOUNCE OF THE LASER BEAM
IS ONE TICK.
92
00:05:23,400 --> 00:05:26,133
JANNA SEES THE LIGHT
GO STRAIGHT UP AND DOWN,
93
00:05:26,133 --> 00:05:31,733
BUT HER CAB-RIDING DOUBLE
SEES SOMETHING QUITE DIFFERENT.
94
00:05:31,733 --> 00:05:33,500
Levin:
FROM THE PERSPECTIVE OF THE CAB,
95
00:05:33,500 --> 00:05:37,333
THE LIGHT APPEARS TO TAKE
A LONG DIAGONAL
96
00:05:37,333 --> 00:05:41,933
AND SO SEEMS AS THOUGH MY CLOCK
IS TAKING TOO LONG TO TICK.
97
00:05:41,933 --> 00:05:44,400
SO IT SEEMS LIKE MY TIME
IS RUNNING SLOW.
98
00:05:44,400 --> 00:05:48,500
Freeman: IF JANNA'S DOPPELGANGER
TURNS ON THE LASER IN THE TAXI,
99
00:05:48,500 --> 00:05:51,900
SHE WILL SEE THE BEAM HITTING
THE CEILING AND FLOOR
100
00:05:51,900 --> 00:05:54,067
RIGHT ABOVE AND BELOW HER.
101
00:05:54,067 --> 00:05:59,400
BUT THE JANNA ON THE STREET
SEES THE BEAM MOVE DIAGONALLY.
102
00:05:59,400 --> 00:06:05,067
BECAUSE THE BEAM HAS LONGER TO
TRAVEL, ITS TICK LOOKS SLOWER.
103
00:06:05,067 --> 00:06:06,800
FROM MY PERSPECTIVE
ON THE STREET,
104
00:06:06,800 --> 00:06:08,200
IF I'M LOOKING INTO THE TAXI,
105
00:06:08,200 --> 00:06:10,967
I SEE THEIR LIGHT
TAKE A LONG DIAGONAL,
106
00:06:10,967 --> 00:06:14,633
AND SO I THINK IT'S TAKING
THEIR CLOCK TOO LONG TO TICK.
107
00:06:14,633 --> 00:06:17,500
FROM MY PERSPECTIVE,
THEIR CLOCKS ARE RUNNING SLOW.
108
00:06:17,500 --> 00:06:18,767
[ WHIRRING ]
109
00:06:18,767 --> 00:06:23,467
Freeman: THE EFFECT INCREASES
THE FASTER YOU GO.
110
00:06:23,467 --> 00:06:26,367
IF THE CAB APPROACHES
THE SPEED OF LIGHT,
111
00:06:26,367 --> 00:06:28,700
THE SPEED LIMIT OF THE UNIVERSE,
112
00:06:28,700 --> 00:06:33,133
TIME OUTSIDE THE CAB
APPEARS TO STAND STILL.
113
00:06:33,133 --> 00:06:36,300
IF THAT TAXI WAS TO FLY BY
AT THE SPEED OF LIGHT,
114
00:06:36,300 --> 00:06:39,067
IT WOULD LOOK LIKE MY CLOCK
WAS NEVER GOING TO TICK,
115
00:06:39,067 --> 00:06:42,633
LIKE MY TIME HAD STOOD STILL,
LIKE TIME WAS FROZEN.
116
00:06:42,633 --> 00:06:45,867
Freeman:
SO, WHICH OBSERVER IS CORRECT?
117
00:06:45,867 --> 00:06:48,533
THE JANNA WHO'S STANDING STILL?
118
00:06:48,533 --> 00:06:50,400
OR THE JANNA IN MOTION?
119
00:06:50,400 --> 00:06:53,533
Levin: MY DOPPELGANGER AND I
JUST FUNDAMENTALLY DISAGREE
120
00:06:53,533 --> 00:06:54,867
ON THE PASSAGE OF TIME,
121
00:06:54,867 --> 00:06:56,133
AND IT'S TRUE.
122
00:06:56,133 --> 00:06:59,067
WE'RE BOTH RIGHT --
TIME IS RELATIVE.
123
00:06:59,067 --> 00:07:05,200
Freeman:
RELATIVITY MEANS THAT THERE CAN
BE NO SINGLE UNIVERSAL TIME.
124
00:07:05,200 --> 00:07:09,567
HOWEVER, THERE WAS ONE MOMENT
WHEN ALL PERSPECTIVES ON TIME
125
00:07:09,567 --> 00:07:11,867
MUST HAVE BEEN THE SAME --
126
00:07:11,867 --> 00:07:16,433
A MOMENT WHEN EVERYTHING EXISTED
IN ONE SINGLE PLACE...
127
00:07:16,433 --> 00:07:18,733
THE BIG BANG.
128
00:07:18,733 --> 00:07:21,933
Levin: ONE OF THE HARDEST THINGS
TO GRASP ABOUT THE IDEA
129
00:07:21,933 --> 00:07:24,733
OF THE BIG BANG
AND THE CREATION OF THE UNIVERSE
130
00:07:24,733 --> 00:07:30,233
IS THE IDEA THAT TIME ITSELF MAY
HAVE BEGUN IN THAT BIG EVENT,
131
00:07:30,233 --> 00:07:36,100
THAT SPACE WAS CREATED IN THE
BIG BANG AND TIME BEGAN TO TICK.
132
00:07:36,100 --> 00:07:40,333
BEFORE OUR BIG BANG, THERE MIGHT
NOT HAVE BEEN SPACE OR TIME.
133
00:07:40,333 --> 00:07:44,100
Freeman: JANNA BELIEVES
THE BIG BANG WAS PROBABLY
134
00:07:44,100 --> 00:07:48,267
WHEN ALL THE VARIOUS TIME
STREAMS IN THE UNIVERSE BEGAN
135
00:07:48,267 --> 00:07:51,867
AND THAT, SINCE THEN,
TIME HAS PASSED DIFFERENTLY
136
00:07:51,867 --> 00:07:57,267
IN DIFFERENT PLACES DEPENDING
ON HOW THOSE PLACES HAVE MOVED.
137
00:07:57,267 --> 00:08:00,067
BUT COULD WE CREATE PLACES
IN OUR UNIVERSE
138
00:08:00,067 --> 00:08:06,267
WHERE TIME CAN APPEAR TO STOP
AND THEN BEGIN AGAIN?
139
00:08:06,267 --> 00:08:09,133
IF WE COULD HIDE AN EVENT
FROM LIGHT,
140
00:08:09,133 --> 00:08:11,767
COULD WE ALSO HIDE IT FROM TIME?
141
00:08:14,067 --> 00:08:16,067
THESE ARE QUESTIONS
142
00:08:16,067 --> 00:08:19,867
PROFESSOR ALEX GAETA
ASKED HIMSELF.
143
00:08:19,867 --> 00:08:22,067
A FORMER
COMPETITION-TENNIS PLAYER,
144
00:08:22,067 --> 00:08:24,733
ALEX IS A PHYSICIST
AT CORNELL UNIVERSITY
145
00:08:24,733 --> 00:08:29,133
SPECIALIZING
IN ULTRA-FAST OPTICS.
146
00:08:29,133 --> 00:08:31,633
THIS TECHNOLOGY IS USUALLY USED
147
00:08:31,633 --> 00:08:34,567
FOR HIGH-SPEED DATA
TRANSMISSION.
148
00:08:34,567 --> 00:08:36,467
BUT AFTER READING A PAPER
149
00:08:36,467 --> 00:08:39,600
WRITTEN BY THEORISTS
AT IMPERIAL COLLEGE,
150
00:08:39,600 --> 00:08:43,967
HE REALIZED IT
COULD ALSO CREATE A GAP IN TIME.
151
00:08:43,967 --> 00:08:46,333
Gaeta: YOU KNOW, LIGHT IS
AN ELECTROMAGNETIC DISTURBANCE.
152
00:08:46,333 --> 00:08:48,067
THE MINUTE THINGS START
CHANGING,
153
00:08:48,067 --> 00:08:50,167
THAT'S AN INDICATION
THAT TIME IS PASSING.
154
00:08:50,167 --> 00:08:52,733
SO ALL THESE CHANGES
THAT ARE OCCURRING
155
00:08:52,733 --> 00:08:55,067
ARE CREATING ALL THESE
ELECTROMAGNETIC DISTURBANCES
156
00:08:55,067 --> 00:08:59,500
THAT WE CAN DETECT
AND MEASURE AS PASSAGE OF TIME.
157
00:08:59,500 --> 00:09:01,600
WHAT WE'VE FIGURED OUT
IS A WAY
158
00:09:01,600 --> 00:09:04,667
OF ESSENTIALLY
TURNING OFF THE LIGHTS,
159
00:09:04,667 --> 00:09:07,767
TURNING THEM BACK ON WITHOUT,
YOU KNOW,
160
00:09:07,767 --> 00:09:11,100
YOU SENSING THAT THEY'VE EVER
ACTUALLY BEEN TURNED OFF.
161
00:09:15,100 --> 00:09:17,833
Freeman: WHAT WOULD HAPPEN
IF YOU TURNED OFF
162
00:09:17,833 --> 00:09:19,233
THE LIGHT SHINING ON TIME
163
00:09:19,233 --> 00:09:21,633
LONG ENOUGH TO HIDE AN EVENT?
164
00:09:21,633 --> 00:09:27,567
SAY, FOR INSTANCE, ALEX IS IN
A CLOSE GAME WITH HIS SON, MAX.
165
00:09:27,567 --> 00:09:31,400
HE'S COMING UP TO MATCH POINT,
AND HE WANTS TO WIN.
166
00:09:31,400 --> 00:09:35,700
IF ALEX COULD CREATE
A HOLE IN TIME,
167
00:09:35,700 --> 00:09:37,867
NO ONE COULD SEE HIM DO THIS...
168
00:09:41,600 --> 00:09:47,733
TO OBSERVERS, INCLUDING HIS SON,
ALEX WINS THE SET WITHOUT PAUSE.
169
00:09:47,733 --> 00:09:48,900
[ REWINDING ]
170
00:09:50,100 --> 00:09:53,900
RIGHT NOW, THIS IS IMPOSSIBLE.
171
00:09:53,900 --> 00:09:57,367
BUT ALL GREAT THINGS
START SMALL.
172
00:10:00,167 --> 00:10:05,500
THIS IS THE KEY COMPONENT
OF ALEX'S EXPERIMENT --
173
00:10:05,500 --> 00:10:07,267
THE SPLIT-TIME LENS.
174
00:10:07,267 --> 00:10:08,367
[ MACHINERY BEEPS ]
175
00:10:08,367 --> 00:10:11,033
IT FOCUSES LIGHT SIGNALS
AND TIME
176
00:10:11,033 --> 00:10:14,400
THE WAY A GLASS LENS
FOCUSES LIGHT IN SPACE.
177
00:10:14,400 --> 00:10:18,033
IN A VACUUM,
THE SPEED OF LIGHT IS CONSTANT,
178
00:10:18,033 --> 00:10:22,667
BUT THAT SPEED CHANGES WHEN
LIGHT PASSES THROUGH A MATERIAL
179
00:10:22,667 --> 00:10:25,867
OR WHEN IT RUNS INTO
ANOTHER LIGHT BEAM.
180
00:10:25,867 --> 00:10:30,267
ALEX'S SPLIT-TIME LENS
USES BOTH TRICKS.
181
00:10:30,267 --> 00:10:34,400
ALEX SHOOTS A LASER
INTO A BEAM OF LIGHT,
182
00:10:34,400 --> 00:10:37,133
SLOWING IT EVER SO SLIGHTLY.
183
00:10:37,133 --> 00:10:40,233
THE BEAM THEN PASSES THROUGH
A GLASS FIBER
184
00:10:40,233 --> 00:10:42,400
WHERE IT SPLITS INTO TWO PARTS,
185
00:10:42,400 --> 00:10:44,733
EACH WITH
A DIFFERENT WAVELENGTH.
186
00:10:44,733 --> 00:10:48,833
THE LOWER WAVELENGTH PULLS AHEAD
OF THE HIGHER WAVELENGTH,
187
00:10:48,833 --> 00:10:51,500
LEAVING A GAP
OF ABSOLUTE DARKNESS.
188
00:10:51,500 --> 00:10:55,433
ANYTHING WITHIN THAT GAP
IS IMPOSSIBLE TO OBSERVE
189
00:10:55,433 --> 00:10:57,800
SINCE THERE IS NO LIGHT THERE.
190
00:10:57,800 --> 00:11:00,433
THE LIGHT THEN PASSES THROUGH
ANOTHER TIME LENS
191
00:11:00,433 --> 00:11:04,233
THAT RE-UNIFIES THE BEAM
WITH NO VISIBLE CHANGE.
192
00:11:08,833 --> 00:11:11,067
USING THIS DEVICE,
193
00:11:11,067 --> 00:11:16,500
ALEX HAS CREATED GAPS THAT LAST
ALMOST A BILLIONTH OF A SECOND.
194
00:11:16,500 --> 00:11:18,400
THAT MAY NOT SOUND LIKE MUCH,
195
00:11:18,400 --> 00:11:21,800
BUT IN THE WORLD OF HIGH-SPEED
INFORMATION TRANSFER,
196
00:11:21,800 --> 00:11:23,400
IT'S SIGNIFICANT.
197
00:11:23,400 --> 00:11:25,467
Gaeta: LET'S SAY YOU HAVE
A DATA STREAM
198
00:11:25,467 --> 00:11:27,633
AND YOU DON'T WANT
TO INTERRUPT IT AT ALL
199
00:11:27,633 --> 00:11:29,600
BUT YOU WANT TO PUT
SOME INFORMATION
200
00:11:29,600 --> 00:11:30,733
INTO THAT DATA STREAM
201
00:11:30,733 --> 00:11:31,833
AND THEN TAKE IT OUT.
202
00:11:31,833 --> 00:11:33,933
SO, BY CREATING THIS GAP,
203
00:11:33,933 --> 00:11:37,067
YOU CAN CREATE THE GAP,
NOT DISTURB THE LIGHT STREAM,
204
00:11:37,067 --> 00:11:39,467
INSERT A LITTLE BIT OF DATA,
TRANSMIT IT,
205
00:11:39,467 --> 00:11:42,300
AND THEN LATER ON,
PULL OUT THAT DATA
206
00:11:42,300 --> 00:11:45,533
AND THEN PUT
THE DATA STREAM BACK TOGETHER.
207
00:11:45,533 --> 00:11:50,100
Freeman:
AND THAT INFORMATION WOULD BE
HIDDEN FROM THE PASSAGE OF TIME.
208
00:11:51,833 --> 00:11:57,200
TODAY, CREATING A LIGHT GAP
THAT LASTS FOR ONE SECOND
209
00:11:57,200 --> 00:12:02,333
WOULD REQUIRE
A MACHINE 186,000 MILES LONG.
210
00:12:02,333 --> 00:12:06,933
SO ALEX WILL HAVE TO WIN
HIS TENNIS MATCHES THE HARD WAY.
211
00:12:06,933 --> 00:12:10,733
BUT THE TECHNOLOGY
IS RAPIDLY EVOLVING.
212
00:12:10,733 --> 00:12:13,233
IN PRINCIPLE,
THERE HAVE BEEN DEMONSTRATIONS
213
00:12:13,233 --> 00:12:16,300
WHERE THEY CAN SLOW DOWN LIGHT
BY FACTORS OF 10 TO THE 7th,
214
00:12:16,300 --> 00:12:17,867
10 TO THE 8th.
215
00:12:17,867 --> 00:12:19,467
IN THE NEAR FUTURE,
IT COULD BE EVEN MORE.
216
00:12:19,467 --> 00:12:21,867
YOU COULD ESSENTIALLY
ALMOST STOP LIGHT,
217
00:12:21,867 --> 00:12:25,067
STORE LIGHT FOR RELATIVELY LONG
PERIODS OF TIME, SECONDS,
218
00:12:25,067 --> 00:12:28,700
AND THEN ESSENTIALLY
RELEASE IT TO TRAVEL, AGAIN,
219
00:12:28,700 --> 00:12:30,600
BACK AT THE SPEED OF LIGHT.
220
00:12:30,600 --> 00:12:34,967
ALEX AND JANNA'S WORK EXPLORES
THE DEEP CONNECTION
221
00:12:34,967 --> 00:12:38,900
BETWEEN OBSERVERS, LIGHT,
AND THE PASSAGE OF TIME.
222
00:12:38,900 --> 00:12:41,133
IT BEGS THE QUESTION,
223
00:12:41,133 --> 00:12:44,933
DOES TIME EXIST IF THERE
IS NO ONE AROUND TO SEE IT?
224
00:12:44,933 --> 00:12:48,300
ONE SCIENTIST SAYS NO --
225
00:12:48,300 --> 00:12:52,567
TIME BEGAN
MUCH LATER THAN WE THINK.
226
00:12:59,800 --> 00:13:02,633
HOW OFTEN HAVE YOU WOKEN UP
IN A DARKENED ROOM
227
00:13:02,633 --> 00:13:06,333
AND HAD NO IDEA
WHAT TIME IT WAS?
228
00:13:06,333 --> 00:13:12,200
HAVE YOU BEEN OUT
FOR MINUTES OR HOURS?
229
00:13:12,200 --> 00:13:17,433
WHEN YOU ARE SLEEPING, YOU HAVE
NO SENSE THAT TIME IS PASSING.
230
00:13:17,433 --> 00:13:21,600
PERHAPS THE COSMOS EXPERIENCES
TIME IN THE SAME WAY.
231
00:13:21,600 --> 00:13:24,767
THE BIG BANG WAS THE MOMENT
OUR UNIVERSE WAS BORN,
232
00:13:24,767 --> 00:13:29,867
BUT WHAT IF IT
DIDN'T WAKE UP RIGHT AWAY?
233
00:13:29,867 --> 00:13:35,400
COULD THERE HAVE BEEN A TIME
WHEN THE UNIVERSE HAD NO TIME?
234
00:13:39,267 --> 00:13:42,667
PROFESSOR LARRY SCHULMAN
IS A LITTLE OUT OF PLACE
235
00:13:42,667 --> 00:13:44,133
IN DRESDEN, GERMANY.
236
00:13:44,133 --> 00:13:47,700
HIS HOME BASE IS NEW YORK'S
CLARKSON UNIVERSITY,
237
00:13:47,700 --> 00:13:51,100
WHICH OFTEN SITS UNDER
A STATIC SHEET OF ICE.
238
00:13:51,100 --> 00:13:53,067
NOT SO DIFFERENT, LARRY SAYS,
239
00:13:53,067 --> 00:13:55,667
FROM THE STATE
OF THE EARLY UNIVERSE,
240
00:13:55,667 --> 00:13:59,767
WHEN, HE CLAIMS,
TIME DID NOT EXIST.
241
00:14:02,900 --> 00:14:05,900
LARRY EXPLORES
THE BEHAVIOR OF SYSTEMS
242
00:14:05,900 --> 00:14:08,200
COMPOSED OF LARGE NUMBERS
OF PARTICLES
243
00:14:08,200 --> 00:14:11,867
SUCH AS THE WATER IN
THIS FOUNTAIN OR THE UNIVERSE.
244
00:14:11,867 --> 00:14:15,067
STATISTICAL MECHANICS
CAN ALSO TELL US ABOUT
245
00:14:15,067 --> 00:14:17,600
THE RELATIONSHIP
OF LIGHT TO TIME.
246
00:14:17,600 --> 00:14:19,067
[ BELL TOLLS ]
247
00:14:19,067 --> 00:14:21,267
LIGHT CARRIES INFORMATION
ABOUT EVENTS.
248
00:14:21,267 --> 00:14:25,833
WE USE IT TO DETERMINE
WHAT IS HAPPENING NOW.
249
00:14:25,833 --> 00:14:28,067
BUT BECAUSE LIGHT
HAS A SPEED LIMIT,
250
00:14:28,067 --> 00:14:33,467
EVERYTHING WE SEE
ACTUALLY TOOK PLACE IN THE PAST.
251
00:14:33,467 --> 00:14:36,667
Schulman:
THE TIME IT WOULD TAKE,
FOR EXAMPLE, FROM THE SUN
252
00:14:36,667 --> 00:14:39,267
IS ABOUT 8 MINUTES
BECAUSE IT'S 93 MILLION MILES,
253
00:14:39,267 --> 00:14:42,433
AND YOU FIGURE WITH A VELOCITY
OF 186,000 MILES PER SECOND,
254
00:14:42,433 --> 00:14:44,600
THAT'S HOW LONG
THE LIGHT WOULD TAKE.
255
00:14:44,600 --> 00:14:47,633
SO, IF THE SUN WERE TO EXPLODE,
FOR EXAMPLE,
256
00:14:47,633 --> 00:14:49,133
YOU WOULD NOT KNOW ABOUT IT
257
00:14:49,133 --> 00:14:53,200
UNTIL EIGHT MINUTES
AFTER THE EVENT.
258
00:14:53,200 --> 00:14:55,833
Freeman: THE LIGHT OF THE MOST
DISTANT PARTS OF THE UNIVERSE
259
00:14:55,833 --> 00:15:00,533
HAS BEEN TRAVELING TOWARD US
FOR 13.8 BILLION YEARS.
260
00:15:00,533 --> 00:15:04,500
THIS IS WHEN THE UNIVERSE BEGAN
IN THE BIG BANG.
261
00:15:08,900 --> 00:15:10,700
THE EARLY UNIVERSE WAS NOTHING
262
00:15:10,700 --> 00:15:12,867
BUT A FIELD
OF CHARGED PARTICLES,
263
00:15:12,867 --> 00:15:16,367
A DENSE, HOT CLOUD OF PLASMA.
264
00:15:16,367 --> 00:15:18,733
PHOTONS, PARTICLES OF LIGHT,
265
00:15:18,733 --> 00:15:22,900
COULD NOT TRAVEL VERY FAR
IN THIS SOUP.
266
00:15:22,900 --> 00:15:27,200
THEN ABOUT 380,000 YEARS
INTO THE LIFE OF THE UNIVERSE,
267
00:15:27,200 --> 00:15:31,600
THERE WAS A SUDDEN CHANGE
CALLED RECOMBINATION.
268
00:15:31,600 --> 00:15:35,067
THIS IS WHEN ATOMS
BEGAN TO FORM.
269
00:15:35,067 --> 00:15:36,467
Schulman:
PRIOR TO RECOMBINATION,
270
00:15:36,467 --> 00:15:37,867
IF AN ELECTRON AND A PROTON
271
00:15:37,867 --> 00:15:40,467
WOULD APPROACH
AND BIND TEMPORARILY,
272
00:15:40,467 --> 00:15:43,233
THEY WOULD BE WHACKED
BY A PHOTON COMING ALONG
273
00:15:43,233 --> 00:15:44,533
AND BE KNOCKED APART.
274
00:15:44,533 --> 00:15:47,067
RECOMBINATION IS A PROCESS
275
00:15:47,067 --> 00:15:49,200
IN WHICH THE ELECTRONS
AND THE PROTONS,
276
00:15:49,200 --> 00:15:50,633
WHICH WERE PREVIOUSLY LOOSE
277
00:15:50,633 --> 00:15:53,067
AND SEPARATED FROM EACH OTHER
IN THE PLASMA,
278
00:15:53,067 --> 00:15:56,733
FINALLY CAN GET TOGETHER.
279
00:15:56,733 --> 00:16:01,567
Freeman:
IT'S A BIT LIKE HOCKEY.
280
00:16:01,567 --> 00:16:05,833
IF YOU IMAGINE
THE HOCKEY PUCK IS A PHOTON.
281
00:16:05,833 --> 00:16:11,733
THIS IS THE RIVER ELBE,
AND SOMETIMES IT FREEZES OVER.
282
00:16:11,733 --> 00:16:13,500
SUPPOSING I WOULD WAIT FOR THAT
283
00:16:13,500 --> 00:16:15,767
AND GO OUT THERE
WITH MY HOCKEY PUCK,
284
00:16:15,767 --> 00:16:18,833
I COULD KNOCK IT
TO THE BANK WITH NO PROBLEM.
285
00:16:18,833 --> 00:16:22,467
Freeman:
BUT THE UNIVERSE JUST AFTER THE
BIG BANG WAS FULL OF OBSTACLES.
286
00:16:22,467 --> 00:16:27,167
Schulman:
NOW SUPPOSE THAT SURROUNDING ME
WERE A BUNCH OF GOALIES
287
00:16:27,167 --> 00:16:28,667
NOT PROTECTING A GOAL,
288
00:16:28,667 --> 00:16:31,867
BUT JUST MAKING SURE THAT
MY HOCKEY PUCK DIDN'T PASS THEM.
289
00:16:31,867 --> 00:16:34,233
SO ALL THESE GOALIES
ARE STANDING AROUND,
290
00:16:34,233 --> 00:16:37,167
AND EVERY TIME I HIT THE PUCK,
ONE OF THEM STOPS IT.
291
00:16:37,167 --> 00:16:39,067
THIS PUCK
IS NOT GONNA GET THROUGH.
292
00:16:39,067 --> 00:16:43,067
Freeman: THIS, LARRY SAYS,
IS THE EARLY UNIVERSE.
293
00:16:43,067 --> 00:16:46,933
PHOTON PUCKS COULDN'T GET PAST
THE ELECTRON AND PROTON GOALIES,
294
00:16:46,933 --> 00:16:50,467
SO LIGHT DIDN'T FLOW.
295
00:16:50,467 --> 00:16:54,067
Schulman:
ON THE OTHER HAND, THESE GOALIES
ARE A LITTLE BIT UNUSUAL,
296
00:16:54,067 --> 00:16:56,067
AND THEY ALTERNATE BOY, GIRL,
BOY, GIRL,
297
00:16:56,067 --> 00:16:58,900
BUT AT FIRST, THEY DIDN'T KNOW
THAT BECAUSE OF THEIR BIG MASKS.
298
00:16:58,900 --> 00:17:01,367
AFTER A WHILE, ONE OF THEM
REMOVES THE MASK,
299
00:17:01,367 --> 00:17:03,467
AND THE GUY NEXT TO HER
SAYS, "OH."
300
00:17:03,467 --> 00:17:04,733
HMM.
301
00:17:04,733 --> 00:17:07,167
THEN THE PUCK
CAN GET RIGHT THROUGH.
302
00:17:07,167 --> 00:17:09,667
ONCE THE PHOTONS
COULD ESCAPE EASILY,
303
00:17:09,667 --> 00:17:11,733
THE WORLD
CHANGED DRAMATICALLY.
304
00:17:11,733 --> 00:17:13,233
[ CHUCKLES ]
305
00:17:14,633 --> 00:17:19,133
IN THE EARLY UNIVERSE,
PHOTONS COULD NEVER MOVE FREELY,
306
00:17:19,133 --> 00:17:21,600
AND THERE WAS NO WAY
TO MEASURE CHANGE.
307
00:17:21,600 --> 00:17:26,467
LARRY ARGUES,
THAT MEANS TIME DID NOT EXIST.
308
00:17:26,467 --> 00:17:29,100
ONLY AFTER RECOMBINATION,
309
00:17:29,100 --> 00:17:32,367
WHEN THE UNIVERSE COOLED
AND ATOMS FORMED,
310
00:17:32,367 --> 00:17:35,300
DID LIGHT BEGIN
TO MOVE AROUND FREELY.
311
00:17:35,300 --> 00:17:41,233
THAT, SAYS LARRY, IS WHEN THE
UNIVERSE'S CLOCK BEGAN TO TICK.
312
00:17:41,233 --> 00:17:44,900
THE VERY EARLIEST POINT,
THERE'S NEVER EVEN A TIME.
313
00:17:44,900 --> 00:17:47,267
BUT EVENTUALLY,
THERE WAS SOMETHING CALLED TIME,
314
00:17:47,267 --> 00:17:50,733
WHICH WAS KEEPING TRACK
OF THE WAY THINGS CHANGED.
315
00:17:50,733 --> 00:17:52,067
[ BELL RINGS ]
316
00:17:52,067 --> 00:17:54,967
THIS COULD EXPLAIN THE BIRTH
OF TIME IN OUR UNIVERSE.
317
00:17:56,600 --> 00:18:03,200
BUT IF OUR UNIVERSE ENDS,
WILL TIME DIE WITH IT?
318
00:18:03,200 --> 00:18:07,933
THIS PHYSICIST THINKS TIME
IS TRULY FUNDAMENTAL --
319
00:18:07,933 --> 00:18:09,867
TIME IS ALWAYS HERE.
320
00:18:09,867 --> 00:18:12,567
IT IS SPACE THAT COMES AND GOES.
321
00:18:16,067 --> 00:18:21,067
TIME MOVES FORWARD,
NEVER BACKWARD.
322
00:18:21,067 --> 00:18:26,100
PHYSICISTS SAY THAT IS BECAUSE
ENERGY ALWAYS DISSIPATES.
323
00:18:27,933 --> 00:18:30,300
IF YOU WIND TIME BACK
FAR ENOUGH,
324
00:18:30,300 --> 00:18:35,533
YOU WOULD SEE THE ENTIRE ENERGY
OF THE UNIVERSE COMING TOGETHER.
325
00:18:35,533 --> 00:18:40,700
AT THE BIG BANG, EVERYTHING
IS FOCUSED ON A SINGLE POINT.
326
00:18:40,700 --> 00:18:44,933
YOU CAN'T WIND TIME BACK
ANY MORE THAN THIS.
327
00:18:44,933 --> 00:18:47,200
OR CAN YOU?
328
00:18:47,200 --> 00:18:51,100
PHYSICIST SEAN CARROLL
329
00:18:51,100 --> 00:18:53,567
OF THE CALIFORNIA INSTITUTE
OF TECHNOLOGY
330
00:18:53,567 --> 00:18:56,767
HAS SPENT MUCH OF HIS CAREER
CONTEMPLATING TIME.
331
00:18:56,767 --> 00:19:00,767
THOUGH THE ORIGIN OF TIME
IS A MYSTERY,
332
00:19:00,767 --> 00:19:03,067
SEAN IS CERTAIN OF ONE THING --
333
00:19:03,067 --> 00:19:07,833
IN OUR UNIVERSE,
TIME HAS A DIRECTION,
334
00:19:07,833 --> 00:19:11,400
AN ARROW
THAT RUNS THROUGH EVERYTHING.
335
00:19:11,400 --> 00:19:17,300
TIME IS A MEASURE OF CHANGE
IN THE UNIVERSE.
336
00:19:17,300 --> 00:19:19,467
IF NOTHING WERE CHANGING
IN THE WORLD,
337
00:19:19,467 --> 00:19:21,700
THERE'D BE NO WAY OF KNOWING
THAT TIME WAS PASSING.
338
00:19:21,700 --> 00:19:23,800
EVERYTHING WOULD BE THE SAME
AT EVERY SINGLE MOMENT.
339
00:19:23,800 --> 00:19:24,933
THERE'D BE NO CLOCKS.
340
00:19:24,933 --> 00:19:27,067
TIME ITSELF WOULD BASICALLY
HAVE NO MEANING.
341
00:19:27,067 --> 00:19:28,567
[ ARROW WHOOSHES ]
342
00:19:31,133 --> 00:19:34,667
Freeman: AS LONG AS SOMETHING IS
CHANGING, NO MATTER HOW SMALL,
343
00:19:34,667 --> 00:19:37,233
TIME IS FLOWING.
344
00:19:37,233 --> 00:19:42,100
AND OUR UNIVERSE IS IN
A CONSTANT STATE OF CHANGE.
345
00:19:42,100 --> 00:19:44,067
AT THE DAWN OF THE UNIVERSE,
346
00:19:44,067 --> 00:19:48,900
AN ENORMOUS AMOUNT OF ENERGY WAS
COMPRESSED INTO A SINGLE POINT.
347
00:19:48,900 --> 00:19:50,867
THEN CAME THE BIG BANG.
348
00:19:52,233 --> 00:19:55,333
SINCE THEN,
WITH EVERY PASSING SECOND,
349
00:19:55,333 --> 00:19:58,867
THAT ENERGY HAS BECOME
MORE AND MORE SPREAD OUT.
350
00:19:58,867 --> 00:20:03,900
THE MEASURE OF THAT SPREADING
OF ENERGY IS CALLED ENTROPY.
351
00:20:03,900 --> 00:20:08,767
SEAN BELIEVES THE FORWARD
MOVEMENT OF TIME, TIME'S ARROW,
352
00:20:08,767 --> 00:20:13,667
IS THE STEADY MOVEMENT FROM
LOW ENTROPY TO HIGH ENTROPY.
353
00:20:13,667 --> 00:20:17,933
BUT WHAT SET TIME'S ARROW
IN MOTION?
354
00:20:17,933 --> 00:20:19,733
Carroll:
THE PUZZLE THAT WE HAVE
355
00:20:19,733 --> 00:20:21,600
IS THAT ENTROPY
TENDS TO INCREASE,
356
00:20:21,600 --> 00:20:24,567
BUT OUR BIG BANG WAS A CONDITION
OF VERY, VERY LOW ENTROPY,
357
00:20:24,567 --> 00:20:27,000
SO HOW DID IT GET THAT WAY?
358
00:20:27,000 --> 00:20:28,833
WHERE COULD IT HAVE COME FROM?
359
00:20:28,833 --> 00:20:33,467
EVERYTHING WE KNOW IN PHYSICS
IS THINGS INCREASING IN ENTROPY.
360
00:20:33,467 --> 00:20:35,100
SO IF YOU GO BACK
TO THE BIG BANG,
361
00:20:35,100 --> 00:20:38,633
THERE WAS NO LOWER ENTROPY PLACE
IT COULD'VE COME FROM.
362
00:20:38,633 --> 00:20:41,467
Freeman:
SEAN SUSPECTS THE ANSWER
363
00:20:41,467 --> 00:20:46,133
IS THAT OUR UNIVERSE IS
THE CHILD OF ANOTHER UNIVERSE.
364
00:20:46,133 --> 00:20:48,967
BUT WHAT WAS THAT UNIVERSE LIKE?
365
00:20:48,967 --> 00:20:51,233
MAYBE LIKE THIS...
366
00:20:51,233 --> 00:20:53,533
IMAGINE A UNIVERSE
THAT'S IN EQUILIBRIUM.
367
00:20:53,533 --> 00:20:56,233
IT'S IN A HIGH-ENTROPY STATE.
IT'S EMPTIED OUT.
368
00:20:56,233 --> 00:20:57,800
IT'S JUST SITTING THERE QUIETLY,
369
00:20:57,800 --> 00:20:59,600
MUCH LIKE
THE WATER IN THIS TANK.
370
00:20:59,600 --> 00:21:02,633
YOU DON'T SEE ANY MOTION.
371
00:21:02,633 --> 00:21:04,967
Freeman:
NOW IMAGINE IN THIS UNIVERSE
372
00:21:04,967 --> 00:21:07,200
WHERE ALL THE ENERGY
IS DISSIPATED,
373
00:21:07,200 --> 00:21:11,767
SUDDENLY AN AREA OF DENSE ENERGY
POPS INTO EXISTENCE,
374
00:21:11,767 --> 00:21:15,900
MUCH LIKE THIS BAG
OF EFFERVESCENT TABLETS.
375
00:21:15,900 --> 00:21:18,767
Carroll: THE SELTZER STARTS
SMALL AND DENSE AND LOW ENTROPY
376
00:21:18,767 --> 00:21:22,333
JUST LIKE OUR UNIVERSE DID NEAR
THE BIG BANG,
377
00:21:22,333 --> 00:21:25,533
BUT THEN WE EXPANDED AND COOLED,
GALAXIES FORMED,
378
00:21:25,533 --> 00:21:29,633
AND THE ARROW OF TIME
PROGRESSES FROM PAST TO FUTURE.
379
00:21:29,633 --> 00:21:32,467
LIKEWISE, THE SELTZER FIZZES
AND BECOMES HIGHER ENTROPY
380
00:21:32,467 --> 00:21:35,367
AS IT MIXES
WITH THE WATER AROUND IT.
381
00:21:35,367 --> 00:21:37,700
AND EVENTUALLY,
JUST LIKE OUR UNIVERSE
382
00:21:37,700 --> 00:21:39,367
WILL COME BACK TO EQUILIBRIUM
383
00:21:39,367 --> 00:21:41,433
AND THE ARROW OF TIME
WILL CEASE,
384
00:21:41,433 --> 00:21:43,067
THE SELTZER REACHES EQUILIBRIUM
385
00:21:43,067 --> 00:21:44,967
BY MIXING WITH
THE WATER AROUND IT,
386
00:21:44,967 --> 00:21:47,767
AND WE'RE BACK TO A STATE
THAT DOESN'T CHANGE ANYMORE,
387
00:21:47,767 --> 00:21:50,500
A STATE WITHOUT
ANY ARROW OF TIME.
388
00:21:50,500 --> 00:21:53,533
Freeman:
BUT HOW COULD A DEAD UNIVERSE,
389
00:21:53,533 --> 00:21:56,700
ONE WITH NO LIFE, STARS,
OR SOLID MATTER,
390
00:21:56,700 --> 00:22:01,967
GIVE BIRTH TO ANOTHER UNIVERSE?
391
00:22:01,967 --> 00:22:05,900
ACCORDING TO QUANTUM PHYSICS,
EVEN AN EMPTY VOID
392
00:22:05,900 --> 00:22:09,567
WILL EXPERIENCE TINY
FLUCTUATIONS OF ENERGY.
393
00:22:09,567 --> 00:22:13,267
THIS MEANS
THAT EVERY ONCE IN A WHILE,
394
00:22:13,267 --> 00:22:16,600
SOMETHING
CAN POP OUT OF NOTHING.
395
00:22:16,600 --> 00:22:20,067
THINK ABOUT THE ATOMIC NUCLEUS
OF A RADIOACTIVE ELEMENT.
396
00:22:20,067 --> 00:22:22,433
IT JUST SITS THERE.
YOU LOOK AT IT.
397
00:22:22,433 --> 00:22:24,833
IT'S NOT CHANGING
AS YOU LOOK AT IT,
398
00:22:24,833 --> 00:22:28,200
BUT THERE IS A POSSIBILITY EVERY
SECOND THAT IT WILL DECAY,
399
00:22:28,200 --> 00:22:30,500
THAT IT WILL SPIT OUT
A NEW PARTICLE.
400
00:22:30,500 --> 00:22:32,967
WHAT WE'RE SAYING IS THAT
SPACE-TIME ITSELF
401
00:22:32,967 --> 00:22:35,367
CAN BE RADIOACTIVE
JUST LIKE THAT NUCLEUS,
402
00:22:35,367 --> 00:22:38,267
EXCEPT INSTEAD OF SPITTING OUT
A NEW PARTICLE,
403
00:22:38,267 --> 00:22:41,567
IT CAN SPIT OUT
AN ENTIRELY NEW UNIVERSE.
404
00:22:41,567 --> 00:22:48,533
Freeman:
NEW UNIVERSES MAY CONSTANTLY
BE POPPING INTO EXISTENCE.
405
00:22:48,533 --> 00:22:52,433
[ POPCORN POPS ]
406
00:22:52,433 --> 00:22:56,367
A RANDOM QUANTUM FLUCTUATION
IN AN ANCIENT UNIVERSE --
407
00:22:56,367 --> 00:22:59,667
A UNIVERSE SO OLD,
TIME FELL APART --
408
00:22:59,667 --> 00:23:04,733
MIGHT EVEN HAVE GIVEN BIRTH
TO OUR UNIVERSE.
409
00:23:04,733 --> 00:23:07,433
THIS PROCESS OF STARTING
WITH NO ARROW OF TIME,
410
00:23:07,433 --> 00:23:10,100
BUDDING OFF A NEW UNIVERSE,
HAVING AN ARROW,
411
00:23:10,100 --> 00:23:12,300
AND THE ARROW ONLY LASTS
FOR A LITTLE WHILE
412
00:23:12,300 --> 00:23:14,133
AS THAT UNIVERSE
EXPANDS AND COOLS,
413
00:23:14,133 --> 00:23:16,667
BUT ONCE IT REACHES EQUILIBRIUM,
THE ARROW STOPS --
414
00:23:16,667 --> 00:23:19,067
THIS COULD HAPPEN MANY, MANY,
MANY, MANY TIMES.
415
00:23:19,067 --> 00:23:20,233
LET'S PUT IT THAT WAY --
416
00:23:20,233 --> 00:23:22,067
MAYBE AN INFINITE NUMBER
OF TIMES,
417
00:23:22,067 --> 00:23:24,367
BUT CERTAINLY
A VERY, VERY LARGE NUMBER,
418
00:23:24,367 --> 00:23:27,067
SO IT'S POSSIBLE
THAT THE UNIVERSE WE CAME FROM
419
00:23:27,067 --> 00:23:29,867
WAS NOWHERE NEAR THE FIRST.
420
00:23:29,867 --> 00:23:36,600
OUR BIG BANG MIGHT
NOT HAVE BEEN THE BEGINNING.
421
00:23:36,600 --> 00:23:41,767
OUR COSMOS' TIME COULD HAVE
ANCESTORS THAT PREDATED IT
422
00:23:41,767 --> 00:23:46,133
AND DESCENDENTS
AFTER THIS UNIVERSE IS GONE.
423
00:23:46,133 --> 00:23:50,267
BUT THERE MAY BE
AN EVEN DEEPER TRUTH ABOUT TIME,
424
00:23:50,267 --> 00:23:52,567
A TRUTH WE WILL NEVER LEARN
425
00:23:52,567 --> 00:23:57,667
UNTIL WE ACCEPT
THAT IT DOESN'T REALLY EXIST.
426
00:24:06,367 --> 00:24:09,300
[ WATCH TICKING ]
427
00:24:09,300 --> 00:24:11,933
WHAT WOULD WE DO WITHOUT TIME?
428
00:24:11,933 --> 00:24:16,367
HOW COULD WE KEEP TRACK
OF THE EVENTS IN OUR LIVES
429
00:24:16,367 --> 00:24:21,067
WITHOUT THE STEADY PULSE
OF MINUTES, DAYS, AND YEARS?
430
00:24:21,067 --> 00:24:25,500
BUT IT MAY BE
THAT NONE OF THAT IS REAL.
431
00:24:25,500 --> 00:24:28,933
IT MAY BE THAT TIME
432
00:24:28,933 --> 00:24:31,333
IS NOTHING MORE THAN A MIRAGE.
[ TICKING STOPS ]
433
00:24:38,133 --> 00:24:39,933
THIS IS THE BELIEF
434
00:24:39,933 --> 00:24:44,133
HELD BY THEORETICAL PHYSICIST
CARLO ROVELLI.
435
00:24:44,133 --> 00:24:46,367
AS A STUDENT
IN HIS NATIVE ITALY,
436
00:24:46,367 --> 00:24:48,333
CARLO WAS ON THE BARRICADES,
437
00:24:48,333 --> 00:24:51,767
FIGHTING AGAINST
THE RESURGENT FASCIST MOVEMENT.
438
00:24:51,767 --> 00:24:54,133
Rovelli:
I WAS YOUNG IN THE '70s,
439
00:24:54,133 --> 00:24:57,533
AND THERE WAS THE BIG DREAM
OF CHANGING THE WORLD.
440
00:24:57,533 --> 00:25:00,300
WE FAILED.
WE DIDN'T CHANGE THE WORLD.
441
00:25:00,300 --> 00:25:02,933
AND SO I THINK
I MOVED INTO SCIENCE
442
00:25:02,933 --> 00:25:05,767
BECAUSE I THOUGHT IT WAS ANOTHER
WAY OF CHANGING THE WORLD,
443
00:25:05,767 --> 00:25:08,067
AND PERHAPS I COULD BE
MORE SUCCESSFUL THERE.
444
00:25:08,067 --> 00:25:13,067
CARLO LEAVES THE CENTRE DE
PHYSIQUE THéORIQUE DE LUMINY,
445
00:25:13,067 --> 00:25:15,767
A THINK TANK
IN THE SOUTH OF FRANCE.
446
00:25:15,767 --> 00:25:19,367
BUT HE'S STILL BREAKING
THE RULES.
447
00:25:19,367 --> 00:25:23,267
AS THE LEADING VOICE OF
THE THEORY OF THERMAL TIME,
448
00:25:23,267 --> 00:25:26,933
HE IS RAISING THE BANNER
FOR A PARADIGM SHIFT
449
00:25:26,933 --> 00:25:28,800
IN FUNDAMENTAL PHYSICS.
450
00:25:28,800 --> 00:25:30,200
IN A NUTSHELL,
451
00:25:30,200 --> 00:25:34,900
THERMAL TIME PROPOSES
THAT TIME DOES NOT EXIST --
452
00:25:34,900 --> 00:25:38,600
AT LEAST NOT AT THE FUNDAMENTAL
LEVEL OF REALITY.
453
00:25:38,600 --> 00:25:41,300
Rovelli: THE IDEA THAT THERE'S
NO TIME ON THE FUNDAMENTAL LEVEL
454
00:25:41,300 --> 00:25:42,700
IS NOT SO COMPLICATED AFTER ALL.
455
00:25:42,700 --> 00:25:44,467
LET ME GIVE YOU AN EXAMPLE.
456
00:25:44,467 --> 00:25:46,700
IMAGINE THAT YOU DESCRIBE
SOMETHING HAPPENING IN TIME,
457
00:25:46,700 --> 00:25:49,067
LIKE THIS IS OSCILLATING
IN TIME.
458
00:25:49,067 --> 00:25:50,067
WHAT DO WE MEAN?
459
00:25:50,067 --> 00:25:51,467
WE MEAN THAT THERE IS SOMETHING
460
00:25:51,467 --> 00:25:52,933
THAT MOVES WITH RESPECT TO TIME.
461
00:25:52,933 --> 00:25:54,067
BUT WHAT IS TIME?
462
00:25:54,067 --> 00:25:56,800
TIME IS THE POSITION
OF THE HAND.
463
00:25:56,800 --> 00:25:59,200
SO WHAT WE
ARE REALLY OBSERVING HERE,
464
00:25:59,200 --> 00:26:02,600
WHAT WE'RE REALLY DOING HERE
IS COMPARING THIS MOVEMENT
465
00:26:02,600 --> 00:26:04,867
WITH THE MOVEMENT
OF THE HANDS OF THE CLOCK.
466
00:26:04,867 --> 00:26:07,867
SO WE DESCRIBE HOW
THE HAND'S CHANGING TIME,
467
00:26:07,867 --> 00:26:10,933
BUT WHAT WE REALLY SEE
IS JUST HOW THIS ANGLE
468
00:26:10,933 --> 00:26:13,100
CHANGES WITH RESPECT
TO THIS ANGLE.
469
00:26:13,100 --> 00:26:16,167
SO, DO WITHOUT TIME MEANS
JUST TO DESCRIBE THE WORLD
470
00:26:16,167 --> 00:26:19,067
IN TERMS OF THE WAY
THE VARIOUS VARIABLES CHANGE
471
00:26:19,067 --> 00:26:20,667
WITH RESPECT TO ONE ANOTHER
472
00:26:20,667 --> 00:26:24,400
WITHOUT EVER HAVING TO BRINGING
THIS UNOBSERVABLE TIME
473
00:26:24,400 --> 00:26:25,933
INTO THE PICTURE.
474
00:26:29,600 --> 00:26:33,967
Freeman:
ISAAC NEWTON INTRODUCED THE IDEA
OF A VARIABLE, "T" FOR "TIME,"
475
00:26:33,967 --> 00:26:38,233
TO DESCRIBE HOW OBJECTS MOVE.
476
00:26:38,233 --> 00:26:40,833
BUT QUANTUM PHYSICS
TREATS TIME DIFFERENTLY
477
00:26:40,833 --> 00:26:43,333
THAN NEWTON'S CLASSICAL SYSTEM.
478
00:26:43,333 --> 00:26:45,767
IN FACT, AT THE PLANCK SCALE,
479
00:26:45,767 --> 00:26:48,467
THE SMALLEST UNIT
OF THE PHYSICAL WORLD,
480
00:26:48,467 --> 00:26:52,300
TIME VARIABLES
SIMPLY DON'T WORK.
481
00:26:52,300 --> 00:26:55,533
CARLO THINKS THE ONLY WAY TO
RESOLVE THIS CONTRADICTION
482
00:26:55,533 --> 00:27:00,300
IS TO GO BACK BEFORE NEWTON
AND GET RID OF THE VARIABLE "T."
483
00:27:00,300 --> 00:27:04,467
HE HAS COMPLETELY REFORMULATED
QUANTUM THEORY
484
00:27:04,467 --> 00:27:06,700
WITHOUT THE USE OF TIME.
485
00:27:06,700 --> 00:27:10,167
BUT THAT'S JUST THE BEGINNING.
486
00:27:10,167 --> 00:27:12,967
THE INTERESTING PART
IS ACTUALLY THE SECOND PART
487
00:27:12,967 --> 00:27:14,633
BECAUSE IF WE ACCEPT THE IDEA
488
00:27:14,633 --> 00:27:17,300
THAT THERE'S NO TIME
ON THE FUNDAMENTAL LEVEL,
489
00:27:17,300 --> 00:27:19,467
NEVERTHELESS
WE DO EXPERIENCE TIME.
490
00:27:19,467 --> 00:27:22,067
TIME PASSES FOR US, RIGHT?
WE LIVE IN TIME.
491
00:27:22,067 --> 00:27:25,767
SO WHERE DOES
THIS TIME EXPERIENCE COME FROM?
492
00:27:27,667 --> 00:27:29,267
[ ENGINE TURNS OVER ]
493
00:27:29,267 --> 00:27:31,067
[ ENGINE REVVING ]
494
00:27:31,067 --> 00:27:35,167
Freeman: THE ANSWER,
CARLO THINKS, IS HEAT.
495
00:27:35,167 --> 00:27:37,400
WHEN YOU ADD HEAT TO MATTER,
496
00:27:37,400 --> 00:27:40,867
IRREVERSIBLE PROCESSES
BEGIN TO TAKE PLACE,
497
00:27:40,867 --> 00:27:43,700
EVENTS THAT CAN'T BE UNDONE.
498
00:27:43,700 --> 00:27:47,600
THINGS BEGIN TO CHANGE IN TIME.
499
00:27:47,600 --> 00:27:51,867
Rovelli:
SO, EVERY TIME THERE IS SOME
LACK OF REVERSIBILITY IN TIME,
500
00:27:51,867 --> 00:27:52,967
THERE'S HEAT.
501
00:27:52,967 --> 00:27:55,533
SO TIME IS TIED TO HEAT,
502
00:27:55,533 --> 00:27:59,067
AND I THINK THAT THE KEY IDEA IS
NOT THAT HEAT COMES FROM TIME,
503
00:27:59,067 --> 00:28:01,067
BUT IS THAT TIME
COMES FROM HEAT.
504
00:28:01,067 --> 00:28:02,600
AND HEAT IS THERMODYNAMICS,
505
00:28:02,600 --> 00:28:07,233
AND WE HAVE UNDERSTOOD THAT
THERMODYNAMIC IS STATISTICS.
506
00:28:07,233 --> 00:28:10,367
SO TIME IS TIED TO STATISTICS.
507
00:28:10,367 --> 00:28:12,933
Freeman: WE DON'T KNOW
THE FINE DETAILS OF NATURE.
508
00:28:12,933 --> 00:28:16,100
WE ONLY UNDERSTAND THE AVERAGE.
509
00:28:16,100 --> 00:28:21,767
WE HAVE ONLY
A STATISTICAL KNOWLEDGE.
510
00:28:21,767 --> 00:28:25,333
SAY CARLO HAS AN OVEN.
511
00:28:25,333 --> 00:28:28,967
TO MEASURE ALL THE QUANTUM
INTERACTIONS INSIDE THE OVEN,
512
00:28:28,967 --> 00:28:31,933
HE WOULD NEED TO MAKE
BILLIONS OF MEASUREMENTS.
513
00:28:31,933 --> 00:28:34,967
BUT NO ONE CAN DO THAT.
514
00:28:34,967 --> 00:28:36,900
SO, INSTEAD, HE SAYS,
AAH!
515
00:28:36,900 --> 00:28:41,200
"THIS OVEN IS 450 DEGREES."
516
00:28:41,200 --> 00:28:44,467
TEMPERATURE IS AN AVERAGE
OF THE ENERGIES
517
00:28:44,467 --> 00:28:46,767
IN THE COUNTLESS PARTICLES
IN A SYSTEM.
518
00:28:46,767 --> 00:28:49,200
IT'S WHAT WE GET
WHEN WE GIVE UP DESCRIBING
519
00:28:49,200 --> 00:28:51,400
WHAT'S HAPPENING
IN THE QUANTUM WORLD,
520
00:28:51,400 --> 00:28:54,933
AND, CARLO SAYS, SO IS TIME.
521
00:28:54,933 --> 00:28:57,400
Rovelli: IF WE COULD SEE
ALL THE DETAILS OF THE WORLD,
522
00:28:57,400 --> 00:28:59,533
WE WOULD SEE
A TIMELESS WORLD IN SOME SENSE.
523
00:28:59,533 --> 00:29:02,967
WE WOULDN'T SEE THIS THING
THAT WE FEEL AS TIME.
524
00:29:06,167 --> 00:29:08,867
Freeman: TO CARLO,
525
00:29:08,867 --> 00:29:12,933
TIME IS JUST A STATEMENT
OF LIMITED INFORMATION.
526
00:29:12,933 --> 00:29:16,833
THE FUNDAMENTAL LEVEL
OF THE UNIVERSE IS TIMELESS.
527
00:29:16,833 --> 00:29:19,100
BUT AT LARGER LEVELS OF REALITY,
528
00:29:19,100 --> 00:29:22,067
WHEN THE INTERACTIONS
OF MATTER AND HEAT
529
00:29:22,067 --> 00:29:24,200
BEGIN TO HAVE VISIBLE EFFECTS,
530
00:29:24,200 --> 00:29:28,267
THE THING
WE CALL "TIME" IS BORN.
531
00:29:28,267 --> 00:29:30,800
TIME BEGAN WHEN SOME SYSTEM,
532
00:29:30,800 --> 00:29:33,467
INSTEAD OF INTERACTING
JUST WITH ITS NEIGHBOR,
533
00:29:33,467 --> 00:29:36,267
INTERACTED WITH
A BIG SET OF SYSTEMS.
534
00:29:36,267 --> 00:29:38,367
SO TIME BEGAN WHEN SOME SYSTEM
535
00:29:38,367 --> 00:29:41,067
STARTED HAVING PARTIAL
INFORMATION,
536
00:29:41,067 --> 00:29:43,400
NOT COMPLETE INFORMATION
ABOUT ITS SURROUNDING.
537
00:29:43,400 --> 00:29:47,800
TIME BEGIN WITH OUR IGNORANCE
AND GROWS WITH OUR IGNORANCE.
538
00:29:47,800 --> 00:29:50,300
Freeman: IT'S A RADICAL VIEW
OF THE UNIVERSE,
539
00:29:50,300 --> 00:29:55,333
BUT CARLO HAS NEVER BEEN AFRAID
TO CHALLENGE THE STATUS QUO.
540
00:29:55,333 --> 00:29:58,067
IS CARLO CORRECT?
541
00:29:58,067 --> 00:30:01,100
IS TIME REALLY
JUST OUR FAILURE TO COMPREHEND
542
00:30:01,100 --> 00:30:03,800
THE DISPERSION OF HEAT?
543
00:30:03,800 --> 00:30:07,033
THIS WOMAN SAYS
THERE IS ANOTHER POSSIBILITY.
544
00:30:07,033 --> 00:30:09,200
TIME IS REAL.
[ CLOCK TICKING ]
545
00:30:09,200 --> 00:30:12,200
BUT IT IS BORN AND REBORN
546
00:30:12,200 --> 00:30:15,067
A TRILLION, TRILLION TIMES
A SECOND.
547
00:30:21,433 --> 00:30:24,000
WHEN I MOVE FROM PLACE TO PLACE,
548
00:30:24,000 --> 00:30:28,467
MY SENSES TELL ME IT HAPPENS
IN ONE CONTINUOUS SWEEP.
549
00:30:28,467 --> 00:30:32,067
BUT ACCORDING TO QUANTUM
MECHANICS, ANY MOVEMENT...
550
00:30:33,500 --> 00:30:36,300
IS ACTUALLY A SERIES
OF MICROSCOPIC JITTERS
551
00:30:36,300 --> 00:30:38,100
THROUGH SPACE.
552
00:30:38,100 --> 00:30:39,333
HUH?
553
00:30:39,333 --> 00:30:41,067
NO ONE HAS YET WORKED OUT
554
00:30:41,067 --> 00:30:44,867
HOW TO APPLY THE THEORY
OF QUANTUM MECHANICS TO TIME,
555
00:30:44,867 --> 00:30:48,800
BUT SOME SCIENTISTS
ARE GETTING VERY CLOSE.
556
00:30:48,800 --> 00:30:55,233
IF THEY SUCCEED, WE WILL HAVE TO
ACCEPT A STRANGE, NEW IDEA --
557
00:30:55,233 --> 00:30:58,533
EVERY MINUTE FRACTION
OF A SECOND,
558
00:30:58,533 --> 00:31:06,333
TIME BURSTS INTO EXISTENCE
OVER AND OVER.
559
00:31:06,333 --> 00:31:13,533
LIKE ALL OF US, FAY DOWKER
EXPERIENCES A FLOW OF TIME.
560
00:31:13,533 --> 00:31:15,333
SHE WAS A GIRL...
561
00:31:15,333 --> 00:31:17,433
THEN A UNIVERSITY STUDENT...
562
00:31:17,433 --> 00:31:21,900
AND NOW SHE'S A PHYSICIST
AT LONDON'S IMPERIAL COLLEGE.
563
00:31:21,900 --> 00:31:24,533
NOTHING IS MORE FUNDAMENTAL
TO OUR EXPERIENCES
564
00:31:24,533 --> 00:31:26,767
THAN THAT WE HAVE
THOSE EXPERIENCES IN TIME.
565
00:31:26,767 --> 00:31:29,067
WE ARE AWARE OF TIME PASSING.
566
00:31:29,067 --> 00:31:32,333
TIME SEEMS TO FLOW.
567
00:31:32,333 --> 00:31:35,333
WE CAN HARDLY MAKE SENSE OF OUR
LIVES EXCEPT IN THE CONTEXT
568
00:31:35,333 --> 00:31:38,167
OF SOME FIXED PAST OF EVENTS
THAT HAVE ALREADY HAPPENED
569
00:31:38,167 --> 00:31:40,200
AND THAT CAN NEVER BE CHANGED
570
00:31:40,200 --> 00:31:42,400
AND SOME OPEN FUTURE OF EVENTS
571
00:31:42,400 --> 00:31:45,367
THAT ARE FREE
AND HAVEN'T HAPPENED YET
572
00:31:45,367 --> 00:31:48,067
AND SOME MYSTERIOUS
AND ELUSIVE MOMENT OF NOW
573
00:31:48,067 --> 00:31:50,867
THAT APPEARS
TO SEPARATE THE TWO.
574
00:31:52,700 --> 00:31:55,667
Freeman:
THIS IDEA SEEMS OBVIOUS.
575
00:31:55,667 --> 00:32:00,433
BUT, ACTUALLY, IT GOES AGAINST
OUR BEST SCIENTIFIC THEORY
576
00:32:00,433 --> 00:32:03,400
OF HOW THE UNIVERSE WORKS.
577
00:32:03,400 --> 00:32:05,433
THE THEORY OF RELATIVITY
578
00:32:05,433 --> 00:32:09,533
TELLS US SPACE AND TIME
ARE INEXTRICABLY JOINED.
579
00:32:09,533 --> 00:32:13,500
ALL TIME THAT WILL EXIST
ALREADY EXISTS
580
00:32:13,500 --> 00:32:16,533
IN A BLOCK WE CALL "SPACE-TIME."
581
00:32:16,533 --> 00:32:19,067
AS WE PASS FROM BIRTH TO DEATH,
582
00:32:19,067 --> 00:32:22,067
WE GLIMPSE
OUR OWN INDIVIDUAL TRAILS
583
00:32:22,067 --> 00:32:25,600
THROUGH THIS
FROZEN SPACE-TIME LANDSCAPE.
584
00:32:25,600 --> 00:32:29,933
BUT FAY BELIEVES THE UNIVERSE
IS NOT A FROZEN BLOCK.
585
00:32:29,933 --> 00:32:31,900
IT IS A GROWING PILE
586
00:32:31,900 --> 00:32:36,300
MADE OF QUANTUM GRAINS
OF SPACE AND TIME.
587
00:32:36,300 --> 00:32:40,633
SPACE-TIME SEEMS SMOOTH
AND CONTINUOUS TO US,
588
00:32:40,633 --> 00:32:42,567
BUT THAT'S JUST BECAUSE
WE'RE VERY LARGE
589
00:32:42,567 --> 00:32:45,067
AND WE SEE THINGS
AT LARGE SCALES.
590
00:32:45,067 --> 00:32:49,333
SO, IF WE IMAGINE
THAT A SOLID CUBE OF SOMETHING,
591
00:32:49,333 --> 00:32:50,967
SAY A SUGAR CUBE,
592
00:32:50,967 --> 00:32:54,100
REPRESENTS A PIECE
OF SPACE-TIME,
593
00:32:54,100 --> 00:32:56,900
THEN FROM FAR AWAY,
THAT LOOKS SOLID.
594
00:32:56,900 --> 00:32:58,533
IT LOOKS LIKE A CHUNK.
595
00:32:58,533 --> 00:33:00,600
BUT WE KNOW
THAT IF YOU ZOOM IN ON IT
596
00:33:00,600 --> 00:33:03,067
AND LOOK AT
ITS MORE FUNDAMENTAL STRUCTURE,
597
00:33:03,067 --> 00:33:05,133
WE SEE THAT IT BREAKS UP
INTO GRAINS.
598
00:33:05,133 --> 00:33:09,067
THE IDEA WITH A GRANULAR MODEL
OF SPACE-TIME IS SIMILAR.
599
00:33:09,067 --> 00:33:13,633
AT FUNDAMENTAL, TINY SCALES,
IT'S GRAINY AND PARTICULATE.
600
00:33:13,633 --> 00:33:16,067
AT LARGE SCALES, IT APPEARS
SMOOTH AND CONTINUOUS.
601
00:33:16,067 --> 00:33:18,567
WE DON'T NOTICE
THAT GRANULARITY.
602
00:33:18,567 --> 00:33:23,733
Freeman: JUST HOW SMALL
IS A GRAIN OF SPACE-TIME?
603
00:33:23,733 --> 00:33:26,900
INCONCEIVABLY SMALL.
604
00:33:26,900 --> 00:33:30,533
ROUGHLY A MILLION, TRILLION,
TRILLION, TRILLIONTH
605
00:33:30,533 --> 00:33:31,900
OF A SECOND.
606
00:33:31,900 --> 00:33:34,967
THIS IS WHAT PHYSICISTS BELIEVE
607
00:33:34,967 --> 00:33:38,300
IS THE SMALLEST POSSIBLE UNIT
OF MEASUREMENT.
608
00:33:38,300 --> 00:33:41,767
FAY THINKS SPACE-TIME IS BUILT
609
00:33:41,767 --> 00:33:46,600
FROM A PRODIGIOUS STACK
OF THESE IMPOSSIBLY TINY GRAINS,
610
00:33:46,600 --> 00:33:50,333
WHICH SHE CALLS
"SPACE-TIME ATOMS."
611
00:33:50,333 --> 00:33:53,433
Dowker: THIS MARRIES TOGETHER
TWO CONCEPTS --
612
00:33:53,433 --> 00:33:57,267
THAT SPACE-TIME
IS FUNDAMENTALLY ATOMIC
613
00:33:57,267 --> 00:34:00,767
OR BITTY OR GRANULAR
AT VERY TINY SCALES
614
00:34:00,767 --> 00:34:03,500
WITH THE NOTION OF CAUSALITY,
615
00:34:03,500 --> 00:34:08,367
THE FACT
THAT CAUSE MUST PRECEDE EFFECT.
616
00:34:08,367 --> 00:34:10,667
SO, FOR EXAMPLE,
IF I HEAR A LOUD NOISE...
617
00:34:10,667 --> 00:34:11,967
[ TIRES SCREECH, CRASH ]
618
00:34:11,967 --> 00:34:14,100
...THEN THAT WILL STARTLE ME,
619
00:34:14,100 --> 00:34:17,400
AND I MIGHT DROP
MY CUP OF COFFEE.
620
00:34:17,400 --> 00:34:20,200
SO THE CAUSE WAS THE LOUD NOISE.
621
00:34:20,200 --> 00:34:25,633
THE EFFECT WAS THE DROPPING
OF MY CUP OF COFFEE.
622
00:34:25,633 --> 00:34:30,200
Freeman:
IF, AS RELATIVITY INSISTS,
623
00:34:30,200 --> 00:34:34,867
ALL OF SPACE AND TIME
ALREADY EXIST,
624
00:34:34,867 --> 00:34:38,733
THE COFFEE CUP WILL ALWAYS FALL,
IS ALWAYS FALLING,
625
00:34:38,733 --> 00:34:41,067
HAS ALWAYS FALLEN.
626
00:34:41,067 --> 00:34:43,567
BUT IN FAY'S VIEW,
627
00:34:43,567 --> 00:34:46,633
THE UNIVERSE IS A SET OF EVENTS
THAT IS FOREVER GROWING.
628
00:34:46,633 --> 00:34:48,200
[ TIRES SCREECH, CRASH ]
629
00:34:48,200 --> 00:34:51,933
WHEN WE OBSERVE THESE
CONNECTED SEQUENCES OF EVENTS,
630
00:34:51,933 --> 00:34:53,967
WHAT SHE CALLS A CAUSAL SET,
631
00:34:53,967 --> 00:34:57,500
WE PERCEIVE
THAT TIME IS PASSING.
632
00:34:57,500 --> 00:35:00,167
Dowker:
A CAUSAL SET CAN GROW
633
00:35:00,167 --> 00:35:04,167
BY THE ACCUMULATION
OF NEW SPACE-TIME ATOMS.
634
00:35:04,167 --> 00:35:08,067
AND THIS BIRTH
OF NEW SPACE-TIME ATOMS
635
00:35:08,067 --> 00:35:12,867
COULD BE THE PASSAGE
OF TIME AS WE KNOW IT.
636
00:35:12,867 --> 00:35:16,067
Freeman: WHAT WE EXPERIENCE
AS THE PRESENT
637
00:35:16,067 --> 00:35:19,233
IS THE BIRTH
OF THESE NEW SPACE-TIME ATOMS.
638
00:35:19,233 --> 00:35:21,867
THE OLD ATOMS DON'T DIE.
639
00:35:21,867 --> 00:35:26,067
THEY PILE UP INTO
THE THING WE CALL "THE PAST."
640
00:35:26,067 --> 00:35:28,267
THE FUTURE HAS YET TO BE BORN.
641
00:35:28,267 --> 00:35:33,067
Dowker: ONCE A SPACE-TIME ATOM
IS BORN AND EXISTS,
642
00:35:33,067 --> 00:35:35,800
IT WILL THEN FORM PART
OF THE PAST.
643
00:35:35,800 --> 00:35:36,900
SO, IN THAT SENSE,
644
00:35:36,900 --> 00:35:38,700
IT ALSO REALIZES OUR SENSE
645
00:35:38,700 --> 00:35:40,333
THAT THE PAST IS FIXED,
646
00:35:40,333 --> 00:35:44,600
THAT THE PAST HAS HAPPENED,
AND THAT IT CANNOT BE CHANGED.
647
00:35:46,800 --> 00:35:50,467
Freeman: TIME MAY NOT BE
A CONTINUOUS RIVER,
648
00:35:50,467 --> 00:35:53,900
BUT RATHER
AN ENDLESS RAIN OF EVENTS.
649
00:35:53,900 --> 00:35:57,367
SO, WHICH CONCEPT
OF TIME IS CORRECT?
650
00:35:57,367 --> 00:36:00,267
ARE WE GETTING CLOSER
TO THE ORIGIN OF TIME?
651
00:36:00,267 --> 00:36:03,167
WE MAY SOON KNOW.
652
00:36:03,167 --> 00:36:08,800
IN THIS LABORATORY, RESEARCHERS
ARE WORKING ON A NEW EXPERIMENT
653
00:36:08,800 --> 00:36:10,667
THAT COULD FOREVER CHANGE
654
00:36:10,667 --> 00:36:13,500
OUR UNDERSTANDING OF TIME
AND THE UNIVERSE.
655
00:36:18,833 --> 00:36:23,167
TIME MAY HAVE BEGUN
AT THE BIG BANG.
656
00:36:23,167 --> 00:36:26,567
IT MAY HAVE ALWAYS BEEN FLOWING.
657
00:36:26,567 --> 00:36:32,400
OR IT COULD BE BORN
TRILLIONS OF TIMES EVERY SECOND.
658
00:36:32,400 --> 00:36:36,067
THIS DEBATE
COULD GO ON FOR DECADES.
659
00:36:36,067 --> 00:36:38,967
OR IT COULD END ANY DAY NOW.
660
00:36:38,967 --> 00:36:41,967
BECAUSE WE MAY
FINALLY HAVE AN EXPERIMENT
661
00:36:41,967 --> 00:36:46,267
THAT REVEALS
THE TRUE NATURE OF TIME.
662
00:36:46,267 --> 00:36:53,067
AT THE BERKELEY CAMPUS
OF THE UNIVERSITY OF CALIFORNIA,
663
00:36:53,067 --> 00:36:56,867
PROFESSOR HARTMUT HAEFFNER
IS BUILDING A TIME RING --
664
00:36:56,867 --> 00:37:01,633
AN OBJECT
THAT WILL ROTATE LIKE THIS DISK.
665
00:37:01,633 --> 00:37:03,733
BUT WHILE THIS METAL RING
666
00:37:03,733 --> 00:37:07,200
IS LEVITATED USING
ELECTROMAGNETIC FORCE,
667
00:37:07,200 --> 00:37:11,767
A TIME RING WILL BE DRIVEN
BY A JITTER IN TIME.
668
00:37:12,933 --> 00:37:15,433
IF IT WORKS,
669
00:37:15,433 --> 00:37:18,633
THIS EXPERIMENT WILL PROVE
A CONTROVERSIAL THEORY --
670
00:37:18,633 --> 00:37:23,100
THE QUANTUM FLUCTUATIONS
THAT HAVE BEEN OBSERVED IN SPACE
671
00:37:23,100 --> 00:37:25,200
ALSO EXIST IN TIME.
672
00:37:25,200 --> 00:37:26,467
[ CLOCK TICKING SPORADICALLY ]
673
00:37:26,467 --> 00:37:28,667
Haeffner:
WE PHYSICISTS LIKE SYMMETRIES,
674
00:37:28,667 --> 00:37:32,267
AND ONE SYMMETRY
IS LIKE SPACE AND TIME.
675
00:37:32,267 --> 00:37:35,067
WE WOULD LIKE TO TREAT THEM
ON THE SAME FOOTING,
676
00:37:35,067 --> 00:37:37,367
SO WHATEVER WE OBSERVE IN SPACE,
677
00:37:37,367 --> 00:37:40,233
WE THINK
WE SHOULD ALSO SEE IN TIME,
678
00:37:40,233 --> 00:37:43,667
AND THIS WOULD ACTUALLY SIMPLIFY
THE DESCRIPTION OF THE UNIVERSE
679
00:37:43,667 --> 00:37:45,067
OR MAKE IT MORE ELEGANT.
680
00:37:45,067 --> 00:37:50,167
Freeman: NANOTECHNOLOGIST
TONGCANG LI, ALSO AT BERKELEY,
681
00:37:50,167 --> 00:37:52,867
DEVISED THE TIME-RING
EXPERIMENT.
682
00:37:52,867 --> 00:37:54,500
HE APPROACHED HARTMUT,
683
00:37:54,500 --> 00:37:58,167
AN EXPERT IN TRAPPING
AND STUDYING ATOMIC PARTICLES.
684
00:37:58,167 --> 00:38:01,067
BUT HARTMUT HAD HIS DOUBTS.
685
00:38:01,067 --> 00:38:03,300
Haeffner: IN THE BEGINNING,
I MEAN, I WAS THINKING,
686
00:38:03,300 --> 00:38:04,400
"I MEAN, THEY ARE CRAZY.
687
00:38:04,400 --> 00:38:06,467
I MEAN,
THIS IS A RIDICULOUS IDEA,"
688
00:38:06,467 --> 00:38:10,767
AND THEN WE START TO TALKING,
AND I REALIZED, "OH, WAIT.
689
00:38:10,767 --> 00:38:12,800
"THIS IS REALLY WEIRD,
BUT THEY ARE RIGHT.
690
00:38:12,800 --> 00:38:14,200
THIS IS THE WAY IT SHOULD BE."
691
00:38:14,200 --> 00:38:17,767
Freeman: ON THIS ELECTRODE,
692
00:38:17,767 --> 00:38:21,100
INSIDE A SPACE THE WIDTH
OF A HUMAN HAIR,
693
00:38:21,100 --> 00:38:25,933
HARTMUT AND HIS TEAM WILL CREATE
A PERFECTLY STATIC LANDSCAPE --
694
00:38:25,933 --> 00:38:29,733
A LANDSCAPE ISOLATED
FROM OUTSIDE ENERGY.
695
00:38:29,733 --> 00:38:33,067
TO FURTHER REDUCE ENERGY
IN THE SYSTEM,
696
00:38:33,067 --> 00:38:36,067
HE MUST TRAP
AND COOL CALCIUM IONS
697
00:38:36,067 --> 00:38:40,833
DOWN TO A FEW BILLIONTHS OF
A DEGREE ABOVE ABSOLUTE ZERO --
698
00:38:40,833 --> 00:38:45,367
COLDER THAN ANYTHING
HAS EVER BEEN COOLED BEFORE.
699
00:38:45,367 --> 00:38:50,067
THIS WILL TAKE THE IONS
DOWN TO THEIR GROUND STATE --
700
00:38:50,067 --> 00:38:52,667
THE STATE
OF MINIMUM POSSIBLE ENERGY.
701
00:38:52,667 --> 00:38:58,333
ONLY THEN CAN THE EFFECTS
OF SPACE BE SEPARATED FROM TIME.
702
00:38:58,333 --> 00:39:02,133
Haeffner: IMAGINE THESE BALL
BEARINGS ARE CALCIUM IONS
703
00:39:02,133 --> 00:39:05,067
AND WE'RE GOING TO INJECT 100
OF THESE CALCIUM IONS
704
00:39:05,067 --> 00:39:06,900
INTO OUR VACUUM CHAMBER.
705
00:39:06,900 --> 00:39:08,600
SO, AT NORMAL TEMPERATURES,
706
00:39:08,600 --> 00:39:12,633
THESE IONS MOVE AROUND RAPIDLY
IN RANDOM DIRECTIONS,
707
00:39:12,633 --> 00:39:16,433
BUT WHEN WE COOL THEM, THEY FORM
THIS RING AND THEY SLOW DOWN,
708
00:39:16,433 --> 00:39:18,600
AND YOU WOULD EXPECT
THAT AT SOME POINT,
709
00:39:18,600 --> 00:39:20,167
THIS RING STOPS MOVING.
710
00:39:20,167 --> 00:39:21,500
IT WOULDN'T ROTATE,
711
00:39:21,500 --> 00:39:24,600
BUT IF THIS THEORY IS CORRECT,
712
00:39:24,600 --> 00:39:28,233
THAT RING SHOULD MOVE,
ROTATE, SPIN.
713
00:39:30,933 --> 00:39:34,200
Freeman: AN OBJECT
AT GROUND STATE SHOULDN'T MOVE,
714
00:39:34,200 --> 00:39:39,100
BECAUSE IT NEITHER CONSUMES
NOR PRODUCES ENERGY.
715
00:39:39,100 --> 00:39:45,067
BUT QUANTUM MECHANICS TELLS US
ZERO DOES NOT MEAN ZERO.
716
00:39:45,067 --> 00:39:49,733
EVEN AT GROUND STATE, THERE WILL
STILL BE QUANTUM FLUCTUATIONS.
717
00:39:49,733 --> 00:39:53,467
IN QUANTUM MECHANICS, THERE'S
ALWAYS THIS FINITE JITTER MOTION
718
00:39:53,467 --> 00:39:54,767
IN THE GROUND STATE.
719
00:39:54,767 --> 00:39:56,167
THINGS WILL STILL MOVE,
720
00:39:56,167 --> 00:39:58,633
BUT THEY WILL MOVE
IN AN UNDIRECTED WAY.
721
00:39:58,633 --> 00:40:00,367
WHAT WE ARE AFTER IS SOMETHING
722
00:40:00,367 --> 00:40:04,600
WHERE THERE IS STILL MOTION
IN A PARTICULAR DIRECTION.
723
00:40:04,600 --> 00:40:07,733
IT WOULD BE DIFFERENT
IN THE SENSE THAT IT'S DIRECTED.
724
00:40:07,733 --> 00:40:10,167
[ WHIRRING ]
725
00:40:10,167 --> 00:40:13,467
Freeman: FREEZING THE IONS
WILL ALLOW THEM
726
00:40:13,467 --> 00:40:17,100
TO MAKE ONLY TINY,
RANDOM MOVEMENTS IN SPACE --
727
00:40:17,100 --> 00:40:19,767
TOO SMALL TO MAKE THE RING MOVE.
728
00:40:19,767 --> 00:40:24,700
BUT IF THE ION RING
BEGINS TO TURN ANYWAY,
729
00:40:24,700 --> 00:40:29,133
IT WILL MEAN THERE HAS BEEN
A FLUCTUATION IN TIME.
730
00:40:29,133 --> 00:40:32,433
FROM THE THEORY PERSPECTIVE,
IT'S NOT AT ALL CLEAR
731
00:40:32,433 --> 00:40:35,500
WHAT IS GOING TO HAPPEN
AT THESE LOW TEMPERATURES.
732
00:40:35,500 --> 00:40:38,733
THERE ARE PEOPLE WHO SAY
THAT THIS RING SHOULD MOVE,
733
00:40:38,733 --> 00:40:40,467
AND OTHERS SAY IT SHOULDN'T.
734
00:40:40,467 --> 00:40:43,300
Freeman:
IF THE TIME RING WORKS,
735
00:40:43,300 --> 00:40:46,100
THEN BOTH SPACE
AND TIME FLUCTUATE.
736
00:40:46,100 --> 00:40:50,433
THAT MIGHT SUPPORT FAY DOWKER'S
THEORY THAT SPACE-TIME
737
00:40:50,433 --> 00:40:54,767
IS CONSTANTLY GENERATING ITSELF
IN QUANTUM DIPS.
738
00:40:54,767 --> 00:40:58,100
AT THE VERY LEAST,
IT WILL DEMONSTRATE
739
00:40:58,100 --> 00:41:01,267
THAT SPACE AND TIME
ARE INEXTRICABLY LINKED
740
00:41:01,267 --> 00:41:03,067
IN THE QUANTUM REALM.
741
00:41:03,067 --> 00:41:07,067
Haeffner: SO, WE HAVE THESE
QUANTUM FLUCTUATIONS IN SPACE,
742
00:41:07,067 --> 00:41:08,833
BUT TIME WE TREAT AS SOMETHING
743
00:41:08,833 --> 00:41:11,567
WHICH YOU CAN KNOW
VERY PRECISELY.
744
00:41:11,567 --> 00:41:15,067
WELL, ACTUALLY, WHAT I WOULD BE
FEELING MUCH MORE HAPPY WITH
745
00:41:15,067 --> 00:41:17,867
IS IF QUANTUM MECHANICS
WOULD ALSO ASSUME
746
00:41:17,867 --> 00:41:20,167
THAT TIME IS FUZZY,
SO TO SPEAK,
747
00:41:20,167 --> 00:41:25,367
THAT YOU CAN'T TELL WHAT TIME IT
IS EXACTLY, ONLY APPROXIMATELY,
748
00:41:25,367 --> 00:41:27,333
THAT YOU HAVE
FLUCTUATIONS OF TIME.
749
00:41:27,333 --> 00:41:28,933
AND I'VE NEVER WORKED
WITH SOMETHING
750
00:41:28,933 --> 00:41:30,600
WHERE TIME FLUCTUATES, SO...
751
00:41:30,600 --> 00:41:32,233
[ CHUCKLES ]
752
00:41:32,233 --> 00:41:34,967
WHEN I SEE IT, MAYBE THEN IT
BECOMES NATURAL TO ME, TOO.
753
00:41:34,967 --> 00:41:36,267
[ WHIRRING ]
754
00:41:40,167 --> 00:41:44,367
IF WE FIND THE ORIGINS OF TIME,
755
00:41:44,367 --> 00:41:49,100
WE WILL ANSWER ONE OF
THE DEEPEST RIDDLES OF CREATION.
756
00:41:49,100 --> 00:41:50,500
BUT WE MIGHT ALSO LEARN
757
00:41:50,500 --> 00:41:55,067
THAT TIME IS MEANINGLESS
TO THE UNIVERSE --
758
00:41:55,067 --> 00:41:57,833
TIME ONLY MATTERS TO US
759
00:41:57,833 --> 00:42:03,167
BECAUSE IT ANCHORS US BETWEEN
OUR MEMORIES OF THE PAST...
760
00:42:03,167 --> 00:42:05,067
AND THE MYSTERY OF THE FUTURE.
61020