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1
00:00:03,499 --> 00:00:08,602
WE'RE ALL MARCHING RELENTLESSLY
FORWARD THROUGH TIME.
2
00:00:08,603 --> 00:00:10,839
[ TIRES SQUEAL ]
3
00:00:10,840 --> 00:00:13,874
WE ACCEPT THAT THERE'S NO
WAY TO GET OFF THIS RIDE
4
00:00:13,875 --> 00:00:15,811
OR TO CHANGE OUR DESTINY.
5
00:00:17,747 --> 00:00:20,047
BUT WHAT IF THAT'S
NOT REALLY TRUE?
6
00:00:20,048 --> 00:00:23,518
WHAT IF WE CAN SEND
MESSAGES BACK IN TIME...
7
00:00:25,753 --> 00:00:27,689
COPY THAT.
8
00:00:27,690 --> 00:00:30,358
...AND CHANGE EVENTS
THAT ALREADY HAPPENED?
9
00:00:30,359 --> 00:00:34,794
CAN THE FUTURE REACH BACK
AND REWRITE THE PRESENT?
10
00:00:34,795 --> 00:00:37,266
CAN TIME GO BACKWARDS?
11
00:00:44,305 --> 00:00:49,211
SPACE, TIME, LIFE ITSELF.
12
00:00:51,180 --> 00:00:55,883
THE SECRETS OF THE COSMOS
LIE THROUGH THE WORMHOLE.
13
00:00:55,884 --> 00:00:58,886
-- Captions by VITAC --
www.vitac.com
14
00:00:58,887 --> 00:01:01,924
CAPTIONS PAID FOR BY
DISCOVERY COMMUNICATIONS
15
00:01:08,631 --> 00:01:13,000
WE THINK OF THE PAST
AS BEING SET IN STONE
16
00:01:13,001 --> 00:01:18,205
AND THE FUTURE AS A BLANK SLATE
WHERE ANYTHING CAN HAPPEN.
17
00:01:18,206 --> 00:01:21,474
BUT EINSTEIN'S
LAWS OF RELATIVITY
18
00:01:21,475 --> 00:01:24,444
BLUR OUR CONCEPT OF TIME.
19
00:01:24,445 --> 00:01:26,780
AS THE GREAT MAN SAID,
20
00:01:26,781 --> 00:01:32,185
THE DISTINCTION BETWEEN THE
PAST, PRESENT, AND FUTURE
21
00:01:32,186 --> 00:01:36,024
IS ONLY A STUBBORNLY
PERSISTENT ILLUSION.
22
00:01:36,025 --> 00:01:41,062
IF ALL OF TIME IS
ALREADY OUT THERE,
23
00:01:41,063 --> 00:01:46,269
CAN WE MAKE THE SANDS OF
TIME FLOW THE OTHER WAY?
24
00:01:48,537 --> 00:01:50,203
CRAIG CALLENDER
25
00:01:50,204 --> 00:01:53,208
OF THE UNIVERSITY OF
CALIFORNIA, SAN DIEGO
26
00:01:53,209 --> 00:01:57,145
IS A PHILOSOPHER WHO STUDIES
PHYSICS AND COGNITIVE SCIENCE.
27
00:01:57,146 --> 00:02:00,348
HE WONDERS WHY WE
DON'T EXPERIENCE TIME
28
00:02:00,349 --> 00:02:02,518
THE WAY IT REALLY IS.
29
00:02:02,617 --> 00:02:04,718
WE ORDINARILY THINK
OF OUR BRAINS
30
00:02:04,719 --> 00:02:07,354
AS JUST RECEIVING THIS
STREAM OF INFORMATION
31
00:02:07,355 --> 00:02:09,656
AND GIVING IT TO US
IN A PASSIVE WAY.
32
00:02:09,657 --> 00:02:12,526
BUT, IN FACT, WE NEVER REALLY
LOOK UNDERNEATH THE HOOD
33
00:02:12,527 --> 00:02:14,628
AND THEN SEE WHAT
REALLY IS GOING ON.
34
00:02:14,629 --> 00:02:17,999
Freeman: WHEN YOU LOOK AT A
SMOOTHLY MOVING CLOCK HAND,
35
00:02:18,000 --> 00:02:21,602
YOUR BRAIN CAN MAKE TIME
APPEAR TO STOP AND START
36
00:02:21,603 --> 00:02:24,506
WHENEVER YOUR MENTAL
FOCUS CHANGES.
37
00:02:24,507 --> 00:02:25,874
IF YOU LOOK AT AN ANALOG CLOCK
38
00:02:25,875 --> 00:02:28,341
AND YOU'RE LOOKING AT THE SECOND
HAND AS IT'S GOING AROUND,
39
00:02:28,342 --> 00:02:30,644
JUST AS YOU GRAB IT
WITH YOUR ATTENTION,
40
00:02:30,645 --> 00:02:33,648
THE SECOND HAND SEEMS
TO PAUSE MOMENTARILY.
41
00:02:33,649 --> 00:02:36,418
Freeman: YOU ALSO
EXPERIENCE A PAUSE IN TIME
42
00:02:36,419 --> 00:02:38,353
WHENEVER YOU LOOK IN THE MIRROR.
43
00:02:38,354 --> 00:02:40,957
SHIFT YOUR GAZE FROM
ONE EYE TO THE OTHER,
44
00:02:41,056 --> 00:02:44,491
AND YOU WILL NEVER SEE
EITHER IN MOTION.
45
00:02:44,492 --> 00:02:47,161
THE BRAIN IS PULLING ALL THESE
TRICKS ON US ALL THE TIME.
46
00:02:47,162 --> 00:02:52,868
Freeman: OUR BRAINS DISTORT TIME TO
HELP US TAKE SNAPSHOTS OF THE WORLD
47
00:02:52,967 --> 00:02:55,402
AND REMEMBER IMPORTANT EVENTS.
48
00:02:55,403 --> 00:03:00,307
IF OUR CONCEPT OF TIME IS
DISTORTED, WHAT'S THE REALITY?
49
00:03:00,308 --> 00:03:03,277
ALBERT EINSTEIN'S
THEORY OF RELATIVITY
50
00:03:03,278 --> 00:03:06,413
ATTEMPTS TO EXPLAIN
HOW TIME TRULY WORKS.
51
00:03:06,414 --> 00:03:08,917
IN HIS VIEW, TIME IS A DIMENSION
52
00:03:08,918 --> 00:03:12,220
JUST LIKE THE THREE
DIMENSIONS OF SPACE.
53
00:03:12,221 --> 00:03:14,957
AND BECAUSE OF THIS, HE BELIEVED
54
00:03:15,056 --> 00:03:20,026
THAT THERE IS NO SUCH THING
AS A SINGLE UNIVERSAL "NOW."
55
00:03:20,027 --> 00:03:26,133
SPACE HAS NO SINGLE UNIVERSAL
HERE, SO WHY SHOULD TIME?
56
00:03:26,134 --> 00:03:27,935
SO, HERE WE'RE IN SAN DIEGO.
57
00:03:27,936 --> 00:03:30,304
THERE ARE OTHER PLACES ...
BOSTON, LONDON, MOSCOW.
58
00:03:30,305 --> 00:03:32,007
THERE ARE ALL THOSE
OTHER PLACES.
59
00:03:32,008 --> 00:03:34,576
WE CAN'T SEE THEM, BUT
WE KNOW THEY EXIST.
60
00:03:34,675 --> 00:03:37,277
SIMILARLY, THINGS ARE LAID
OUT IN TIME THAT WAY, TOO.
61
00:03:37,278 --> 00:03:40,013
Freeman: ALL OF
TIME ALREADY EXISTS
62
00:03:40,014 --> 00:03:42,883
ALONGSIDE THE OTHER
THREE DIMENSIONS.
63
00:03:42,884 --> 00:03:45,387
IN EINSTEIN'S
DESCRIPTION OF TIME,
64
00:03:45,388 --> 00:03:48,355
CRAIG'S ACTIONS OF
GETTING INTO THE WATER,
65
00:03:48,356 --> 00:03:50,424
PADDLING OVER IT,
AND GETTING OUT
66
00:03:50,425 --> 00:03:53,595
ALL HAPPEN ALONGSIDE
ONE ANOTHER.
67
00:03:54,896 --> 00:03:57,331
PHYSICISTS CALL THIS
VIEW OF REALITY
68
00:03:57,332 --> 00:04:00,567
WHERE ALL OF TIME AND
SPACE ALREADY EXIST
69
00:04:00,568 --> 00:04:02,704
THE BLOCK UNIVERSE,
70
00:04:02,705 --> 00:04:05,541
AND IT LOOKS LIKE THIS CAKE.
71
00:04:05,640 --> 00:04:08,508
SO, LET THIS END OF THE
BLOCK BE THE BIG BANG,
72
00:04:08,509 --> 00:04:11,512
THIS END OF THE BLOCK BE
THE END OF THE UNIVERSE.
73
00:04:11,513 --> 00:04:13,815
ALL THE EVENTS ARE
THERE LAID OUT.
74
00:04:13,816 --> 00:04:15,984
SO SOME OF THESE EVENTS
MIGHT BE YOUR BIRTH.
75
00:04:15,985 --> 00:04:17,420
SOME OF THEM MIGHT BE RIGHT NOW.
76
00:04:17,519 --> 00:04:18,720
SOME OF THEM MIGHT
BE YOUR DEATH.
77
00:04:18,721 --> 00:04:20,188
THEY'RE ALL THERE.
78
00:04:20,189 --> 00:04:24,991
Freeman: OF COURSE, WE DON'T SEE
THE BLOCK UNIVERSE ALL AT ONCE.
79
00:04:24,992 --> 00:04:29,263
WE EACH EXPERIENCE THE UNIVERSE
AS OUR OWN SLICE OF NOW.
80
00:04:29,264 --> 00:04:32,333
EVERYTHING BEHIND THE
SLICE BECOMES OUR PAST,
81
00:04:32,334 --> 00:04:36,270
AND EVERYTHING IN FRONT
REPRESENTS OUR FUTURE.
82
00:04:36,271 --> 00:04:39,707
Callender: SO EACH OBSERVER
WILL HAVE A DIFFERENT SLICE,
83
00:04:39,708 --> 00:04:42,143
CARVING IT UP INTO PAST,
PRESENT, AND FUTURE.
84
00:04:42,144 --> 00:04:45,179
THAT KNIFE WILL
BE THEIR PRESENT.
85
00:04:45,180 --> 00:04:49,284
Freeman: BUT JUST AS EVERYONE
CAN'T HAVE THE SAME HERE,
86
00:04:49,285 --> 00:04:52,652
NOT EVERYONE CAN AGREE
ON WHAT NOW IS.
87
00:04:52,653 --> 00:04:55,056
OR TO PUT IT ANOTHER WAY,
88
00:04:55,057 --> 00:04:59,727
EVERYONE HAS THEIR OWN
UNIQUELY ANGLED NOW SLICE.
89
00:04:59,728 --> 00:05:03,265
CONSIDER YOUR OWN SLICE
OF NOW HERE ON EARTH.
90
00:05:03,266 --> 00:05:05,835
YOUR NOW INCLUDES LIGHT
IN THE NIGHT SKY
91
00:05:05,836 --> 00:05:08,703
FROM THE NEARBY STAR
ALPHA CENTAURI.
92
00:05:08,704 --> 00:05:12,506
BUT THAT LIGHT HAS TAKEN OVER
FOUR YEARS TO REACH YOU.
93
00:05:12,507 --> 00:05:15,475
SO YOUR PRESENT SLICE
IS ACTUALLY ANGLED
94
00:05:15,476 --> 00:05:19,479
TO INCLUDE PAST EVENTS
ON ALPHA CENTAURI.
95
00:05:19,480 --> 00:05:23,318
FOR SOMEONE ON ALPHA CENTAURI
LOOKING TOWARD EARTH,
96
00:05:23,319 --> 00:05:27,789
THEIR NOW SLICE INCLUDES EVENTS
FROM FOUR YEARS IN THE PAST
97
00:05:27,790 --> 00:05:29,457
ON OUR PLANET.
98
00:05:29,458 --> 00:05:30,924
Callender: AND EINSTEIN
IS SAYING THAT
99
00:05:30,925 --> 00:05:32,693
THERE'S NO DISTINGUISHED
CUTTING UP OF THE CAKE.
100
00:05:32,694 --> 00:05:36,898
THEY'RE ALL EQUALLY LEGITIMATE
WAYS OF CUTTING UP EVERYTHING.
101
00:05:36,899 --> 00:05:40,001
AND THOSE SLICES WILL
GRAB DIFFERENT EVENTS
102
00:05:40,002 --> 00:05:42,035
IN THE SPACE TIME MANIFOLD.
103
00:05:42,036 --> 00:05:47,441
Freeman: LIGHT ZIPS AROUND OUR PLANET
IN A SMALL FRACTION OF A SECOND,
104
00:05:47,442 --> 00:05:52,614
SO OUR BRAINS TRICK US INTO
AGREEING ON A SINGLE SHARED NOW.
105
00:05:52,615 --> 00:05:55,417
AND OUR BRAINS ALSO
FOOL US INTO BELIEVING
106
00:05:55,418 --> 00:05:59,352
THAT TIME IS MOVING, EVEN THOUGH
THE PAST, PRESENT, AND FUTURE
107
00:05:59,353 --> 00:06:00,455
EXIST TOGETHER.
108
00:06:00,456 --> 00:06:04,124
CRAIG THINKS THIS IS
BECAUSE OUR BRAINS
109
00:06:04,125 --> 00:06:07,895
ARE STRINGING TOGETHER
INDIVIDUAL SLICES OF NOW,
110
00:06:07,896 --> 00:06:10,231
LIKE FRAMES OF A MOVIE.
111
00:06:10,232 --> 00:06:12,167
Callender: WHAT'S REALLY
GOING ON, I THINK,
112
00:06:12,168 --> 00:06:14,234
IS THAT WE HAVE MEMORIES
ONLY IN ONE DIRECTION.
113
00:06:14,235 --> 00:06:16,304
YOU JUST CAN'T GET
MEMORIES OF THE FUTURE.
114
00:06:16,305 --> 00:06:19,472
SO THERE'S BABY YOU,
ADULT YOU, ET CETERA.
115
00:06:19,473 --> 00:06:23,210
YOU HAVE THIS THREAD OF IDENTITY
RUNNING THROUGH SPACE TIME.
116
00:06:23,211 --> 00:06:25,679
THAT'S WHY IT FEELS
LIKE I'M FLOWING,
117
00:06:25,680 --> 00:06:28,782
BECAUSE I'M BUILDING UP
THIS STORY OF THE SELF.
118
00:06:28,783 --> 00:06:31,585
THERE'S NOTHING REALLY
MOVING THROUGH THE BLOCK.
119
00:06:31,586 --> 00:06:36,691
Freeman: OUR SENSATIONS OF TIME APPEAR
TO BE DISTORTED, EVEN FABRICATED,
120
00:06:36,692 --> 00:06:40,660
SO CAN WE LEARN TO SEE
TIME DIFFERENTLY?
121
00:06:40,661 --> 00:06:44,499
TIME NEVER STOPS.
122
00:06:44,500 --> 00:06:49,035
BUT OUR BRAINS CAN ONLY
REGISTER ONE MOMENT IN TIME ...
123
00:06:49,036 --> 00:06:52,273
THE MOMENT WE CALL THE PRESENT.
124
00:06:52,274 --> 00:06:56,710
IF ALL OF TIME DOES
EXIST AT ONCE,
125
00:06:56,711 --> 00:07:00,982
COULDN'T WE CHANGE OUR
VIEWPOINT OF TIME
126
00:07:00,983 --> 00:07:05,588
AND MAYBE SEE OUR OWN FUTURE?
127
00:07:07,088 --> 00:07:09,823
JIM HARTLE IS A PHYSICIST
128
00:07:09,824 --> 00:07:13,427
AT THE UNIVERSITY OF
CALIFORNIA AT SANTA BARBARA.
129
00:07:13,428 --> 00:07:16,931
HE SPENT DECADES TRYING
TO WRAP HIS HEAD AROUND
130
00:07:16,932 --> 00:07:19,165
EINSTEIN'S THEORY OF TIME.
131
00:07:19,166 --> 00:07:21,135
Hartle: THERE ISN'T A NOTION
OF PAST, PRESENT, AND FUTURE
132
00:07:21,136 --> 00:07:22,970
IN SPECIAL RELATIVITY,
133
00:07:22,971 --> 00:07:26,674
SO OUR IMPRESSION OF PAST,
PRESENT, AND FUTURE
134
00:07:26,675 --> 00:07:29,876
HAS TO COME FROM THE WAY
THAT WE'RE CONSTRUCTED.
135
00:07:29,877 --> 00:07:34,215
Freeman: OUR BRAINS CONSTANTLY
PROCESS INFORMATION,
136
00:07:34,216 --> 00:07:37,785
AND WHATEVER IS MOST
RECENT BECOMES NOW.
137
00:07:37,786 --> 00:07:41,422
OUR BRAINS THEN MOVE THAT
INFORMATION INTO OUR MEMORY
138
00:07:41,423 --> 00:07:43,289
TO MAKE ROOM FOR A NEW NOW.
139
00:07:43,290 --> 00:07:46,794
Hartle: THE PRESENT IS THE
MOST RECENT INFORMATION.
140
00:07:46,795 --> 00:07:49,963
THE PAST, RIGHT, IS WHAT
YOU'VE GOT IN MEMORY.
141
00:07:49,964 --> 00:07:52,633
WE TAKE THE TWO, AND WE
TRY TO PREDICT, RIGHT,
142
00:07:52,634 --> 00:07:54,770
WHAT WE'RE GONNA
SEE IN THE FUTURE.
143
00:07:56,672 --> 00:08:00,407
Freeman: BUT WHAT IF WE
PERCEIVE TIME DIFFERENTLY?
144
00:08:00,408 --> 00:08:02,676
JIM IMAGINED BRAINS CONSTRUCTED
145
00:08:02,677 --> 00:08:06,181
TO INTERPRET SEQUENCES
OF EVENTS IN NEW WAYS.
146
00:08:06,182 --> 00:08:08,717
TAKE THE FAST MOVING
GAME OF ROLLER HOCKEY.
147
00:08:08,718 --> 00:08:10,951
THE PLAYERS ARE ALL
MAKING DECISIONS
148
00:08:10,952 --> 00:08:13,487
BASED ON WHAT'S HAPPENING
IN THEIR PRESENT.
149
00:08:13,488 --> 00:08:17,891
WHAT WOULD HAPPEN TO A PLAYER IF
HIS EXPERIENCE OF THE PRESENT
150
00:08:17,892 --> 00:08:21,429
WAS WHAT EVERYONE ELSE
SEES AS THE PAST?
151
00:08:21,430 --> 00:08:25,099
LET'S SAY THE GOGGLES JIM
HANDS TO THIS PLAYER
152
00:08:25,100 --> 00:08:27,367
CHANGED HIS PERSPECTIVE ON TIME.
153
00:08:27,368 --> 00:08:30,337
LET'S SAY THAT THOSE
GOGGLES CONTAIN A PROGRAM
154
00:08:30,338 --> 00:08:32,539
THAT FILTERS THE
EVENTS IN OUR PRESENT
155
00:08:32,540 --> 00:08:34,708
AND DELAYS THEM BY 10 SECONDS.
156
00:08:34,709 --> 00:08:39,212
Freeman: AFTER THE FACE OFF, BOTH
TEAMS SCATTER TOWARD THE GOAL.
157
00:08:39,213 --> 00:08:42,116
THE GOGGLED PLAYER
REMAINS AT CENTER ICE.
158
00:08:42,117 --> 00:08:45,453
WHAT HAPPENED 10 SECONDS
AGO FOR EVERYONE ELSE
159
00:08:45,454 --> 00:08:48,222
FEELS LIKE THE PRESENT TO HIM.
160
00:08:48,223 --> 00:08:50,857
WHEN THE GOGGLED PLAYER
FINALLY PERCEIVES THE PUCK
161
00:08:50,858 --> 00:08:52,126
MOVING TOWARD THE GOAL,
162
00:08:52,127 --> 00:08:54,794
THE REST OF THE PLAYERS
HAVE ALREADY SKATED
163
00:08:54,795 --> 00:08:56,597
TO A CORNER OF THE RINK.
164
00:08:56,598 --> 00:09:00,068
THAT PLAYER WOULD NEVER
CATCH UP WITH THE PUCK.
165
00:09:00,069 --> 00:09:04,105
Freeman: IN HOCKEY, A PLAYER
SEEING THE PAST AS HIS NOW
166
00:09:04,106 --> 00:09:07,107
WOULD BE PERPETUALLY
LATE TO THE ACTION
167
00:09:07,108 --> 00:09:09,742
AND WOULD BE A USELESS PLAYER.
168
00:09:09,743 --> 00:09:14,548
IN THE NATURAL WORLD, THE
REPERCUSSIONS ARE MORE SEVERE.
169
00:09:14,549 --> 00:09:17,552
IF A HUNTER BELIEVED HIS PREY
TO BE IN A TIME AND PLACE
170
00:09:17,553 --> 00:09:19,953
THAT IT HAD ALREADY LEFT,
171
00:09:19,954 --> 00:09:22,256
HE'D NEVER CATCH A MEAL,
172
00:09:22,257 --> 00:09:26,427
AND HIS DAYS WOULD BE NUMBERED.
173
00:09:26,428 --> 00:09:28,663
NATURAL SELECTION HAS GUIDED
THE DEVELOPMENT OF OUR BRAINS
174
00:09:28,664 --> 00:09:30,063
TO COMPUTE IN THAT WAY.
175
00:09:30,064 --> 00:09:33,300
THAT'S THE MOST EFFICIENT
SURVIVAL MECHANISM,
176
00:09:33,301 --> 00:09:36,404
AND ALTERNATIVES TO
IT GET WEEDED OUT.
177
00:09:36,405 --> 00:09:40,140
Freeman: JIM THEN WONDERED WHETHER
A BRAIN ARTIFICIALLY CONSTRUCTED
178
00:09:40,141 --> 00:09:42,977
TO EXPERIENCE MORE THAN ONE NOW
179
00:09:42,978 --> 00:09:45,847
MIGHT GAIN SOME ADVANTAGE.
180
00:09:45,848 --> 00:09:48,649
Hartle: IT IS POSSIBLE
TO IMAGINE BRAINS
181
00:09:48,650 --> 00:09:51,986
THAT HAVE CONSCIOUS FOCUS ON
ALL PARTS OF ITS MEMBRANE
182
00:09:51,987 --> 00:09:53,219
IN THE PRESENT,
183
00:09:53,220 --> 00:09:56,189
BUT IT WOULD WASTE VALUABLE
COMPUTATIONAL RESOURCES
184
00:09:56,190 --> 00:09:58,458
CONSIDERING OPTIONS
THAT ARE USELESS.
185
00:09:58,459 --> 00:10:02,395
Freeman: IMAGINE THE HOCKEY
PLAYER HAVING TO MAKE DECISIONS
186
00:10:02,396 --> 00:10:05,131
WHERE ALL MOMENTS ARE
EQUALLY ACCESSIBLE,
187
00:10:05,132 --> 00:10:08,435
EVERYTHING IN HIS
EXPERIENCE FEELS LIKE NOW.
188
00:10:08,436 --> 00:10:12,039
JIM SUSPECTS A BRAIN LIKE THIS
WOULD FREEZE INTO INACTION,
189
00:10:12,040 --> 00:10:15,809
OVERWHELMED BY A
UNIVERSE OF CHOICES.
190
00:10:15,810 --> 00:10:17,310
OUR PAST, PRESENT,
AND FUTURE WAY
191
00:10:17,311 --> 00:10:19,380
OF ORGANIZING THE FLOW OF TIME
192
00:10:19,381 --> 00:10:22,817
HAS EVOLVED AS BEST FOR
OUR BIOLOGICAL SURVIVAL.
193
00:10:22,818 --> 00:10:25,754
OUR BRAINS HAVE CREATED
A NARRATIVE OF TIME
194
00:10:25,755 --> 00:10:27,822
THAT BEST SUITS OUR ENVIRONMENT.
195
00:10:27,823 --> 00:10:31,025
Freeman: BUT COULD OTHER
PERCEPTIONS OF WHAT NOW IS
196
00:10:31,026 --> 00:10:34,028
WORK BETTER IN OTHER
ENVIRONMENTS?
197
00:10:34,029 --> 00:10:38,900
IT'S A VERY INTRIGUING QUESTION
WHETHER BEINGS ON OTHER PLANETS,
198
00:10:38,901 --> 00:10:40,367
FOR EXAMPLE,
199
00:10:40,368 --> 00:10:43,002
WOULD HAVE THE SAME METHOD OF
ORGANIZING TIME THAT WE DO ...
200
00:10:43,003 --> 00:10:44,837
PAST, PRESENT, AND FUTURE.
201
00:10:44,838 --> 00:10:49,309
Freeman: PERHAPS ON OTHER WORLDS,
ALIEN MINDS HAVE DEVISED WAYS
202
00:10:49,310 --> 00:10:52,179
TO AUGMENT THEIR OWN
EXPERIENCE OF TIME.
203
00:10:52,180 --> 00:10:54,548
THEY MAY BE ABLE TO
THRIVE WITH KNOWLEDGE
204
00:10:54,549 --> 00:10:58,554
OF THE PAST, PRESENT,
AND FUTURE ALL AT ONCE.
205
00:11:00,454 --> 00:11:05,425
COULD WE, OURSELVES, LEARN
HOW TO MANAGE MULTIPLE NOWS?
206
00:11:05,426 --> 00:11:07,895
IT COULD BE MORE
LIKELY THAN YOU THINK.
207
00:11:07,896 --> 00:11:10,396
ONE SCIENTIST THINKS
HE'S SEEN THE FUTURE
208
00:11:10,397 --> 00:11:16,238
AND DETECTED ITS SHADOW
CAST BACKWARD IN TIME.
209
00:11:17,999 --> 00:11:20,267
YOU CAN'T GET TO
WHERE YOU WANT TO GO
210
00:11:20,268 --> 00:11:22,603
WITHOUT TAKING THE FIRST STEP.
211
00:11:22,604 --> 00:11:25,273
SEEMS SIMPLE ENOUGH.
212
00:11:26,542 --> 00:11:31,377
BUT NEW RESEARCH IS HINTING THAT
THE OPPOSITE COULD ALSO BE TRUE.
213
00:11:31,378 --> 00:11:36,585
WHERE YOU END UP MIGHT INFLUENCE
THE PATH YOU'RE TAKING NOW.
214
00:11:39,320 --> 00:11:41,955
SANDU POPESCU IS A
PROFESSOR OF PHYSICS
215
00:11:41,956 --> 00:11:44,959
AT THE UNIVERSITY OF
BRISTOL IN ENGLAND.
216
00:11:44,960 --> 00:11:48,194
HE'S MADE AN
UNSETTLING DISCOVERY.
217
00:11:48,195 --> 00:11:53,635
THE FUTURE MIGHT BE REACHING
BACK AND MEDDLING WITH THE PAST.
218
00:11:53,636 --> 00:11:56,972
THE IDEA DAWNED ON SANDU
WHILE HE AND HIS COLLEAGUES
219
00:11:56,973 --> 00:12:00,275
WERE EXPLORING THE FUNDAMENTAL
MATHEMATICAL CONCEPT
220
00:12:00,276 --> 00:12:03,611
CALLED THE PIGEONHOLE PRINCIPLE.
221
00:12:03,612 --> 00:12:05,680
IF I HAVE THREE PIGEONS
222
00:12:05,681 --> 00:12:09,583
AND I WANT TO PUT THEM
INTO TWO PIGEONHOLES,
223
00:12:09,584 --> 00:12:14,789
THEN I NECESSARILY END UP
WITH TWO PIGEONS IN ONE HOLE.
224
00:12:14,790 --> 00:12:16,824
Freeman: IT'S COMMON SENSE.
225
00:12:16,825 --> 00:12:20,161
THREE PIGEONS WON'T FIT
INTO TWO PIGEONHOLES
226
00:12:20,162 --> 00:12:22,496
WITHOUT TWO OF THEM
HAVING TO SHARE.
227
00:12:22,497 --> 00:12:25,967
BUT IF THE PIGEONS WERE SHRUNK
DOWN TO THE SIZE OF ATOMS,
228
00:12:25,968 --> 00:12:28,569
THEN THEY WOULD FOLLOW
THE STRANGE RULES
229
00:12:28,570 --> 00:12:30,371
OF QUANTUM MECHANICS,
230
00:12:30,372 --> 00:12:33,840
AND THEN THREE PIGEONS
COULD FIT INTO TWO SPACES
231
00:12:33,841 --> 00:12:36,844
AND NEVER SHARE THE SAME SPACE.
232
00:12:36,845 --> 00:12:41,348
I CAN ARRANGE A SITUATION
IN WHICH I CAN GUARANTEE
233
00:12:41,349 --> 00:12:46,055
THAT NO TWO PARTICLES WILL
BE FOUND IN THE SAME BOX.
234
00:12:47,522 --> 00:12:49,957
Freeman: THIS BIZARRE
EFFECT IS POSSIBLE
235
00:12:49,958 --> 00:12:52,059
BECAUSE MINISCULE
QUANTUM OBJECTS
236
00:12:52,060 --> 00:12:54,862
DON'T HAVE DEFINITE
FIXED LOCATIONS.
237
00:12:54,863 --> 00:12:59,434
Popescu: QUANTUM PARTICLES IN
GENERAL BEHAVE VERY DIFFERENTLY
238
00:12:59,435 --> 00:13:02,603
FROM EVERYDAY OBJECTS
THAT WE KNOW.
239
00:13:02,604 --> 00:13:07,340
FOR EXAMPLE, AN ATOM CAN BE
IN TWO OR EVEN MORE PLACES
240
00:13:07,341 --> 00:13:09,010
AT THE SAME TIME.
241
00:13:09,011 --> 00:13:11,512
Freeman: BUT WHEN SANDU
BEGAN THINKING ABOUT
242
00:13:11,513 --> 00:13:14,982
EXACTLY HOW PARTICLES AVOID
SHARING A SPACE WITH ONE ANOTHER,
243
00:13:14,983 --> 00:13:18,652
HE FOUND IT HAD A
RADICAL CONSEQUENCE.
244
00:13:18,653 --> 00:13:23,523
INFORMATION ABOUT THE FUTURE CAN
TRAVEL BACKWARDS THROUGH TIME.
245
00:13:23,524 --> 00:13:29,129
Popescu: THE FACT THAT WHEN DEALING
WITH MICROSCOPIC PARTICLES,
246
00:13:29,130 --> 00:13:31,299
THE RESULT OF AN EXPERIMENT
247
00:13:31,300 --> 00:13:34,767
IS NOT DETERMINED
FROM THE BEGINNING
248
00:13:34,768 --> 00:13:39,873
OPENS THE POSSIBILITY THAT THE
FUTURE WILL INFLUENCE THE PAST.
249
00:13:39,874 --> 00:13:42,910
Freeman: SANDU HAS
SET UP AN EXPERIMENT
250
00:13:42,911 --> 00:13:45,681
TO EXPLORE THIS
CURIOUS SITUATION.
251
00:13:47,147 --> 00:13:49,883
HE FIRES BATCHES
OF THREE ELECTRONS
252
00:13:49,884 --> 00:13:52,687
INTO A DIAMOND SHAPED APPARATUS.
253
00:13:54,656 --> 00:13:56,122
IT HAS TWO TRACKS.
254
00:13:56,123 --> 00:13:59,826
ONE GOES TO THE LEFT, THE
OTHER GOES TO THE RIGHT
255
00:13:59,827 --> 00:14:02,964
BEFORE MERGING AGAIN
AT A SECOND FORK.
256
00:14:02,965 --> 00:14:06,734
THESE TWO TRACKS ARE
THE TWO PIGEONHOLES.
257
00:14:08,902 --> 00:14:11,003
TO UNDERSTAND HOW SANDU STUDIES
258
00:14:11,004 --> 00:14:13,608
WHAT THE THREE
ELECTRONS ARE DOING,
259
00:14:13,609 --> 00:14:16,844
THINK OF THEM AS THREE
HAT WEARING TOY PIGEONS.
260
00:14:16,845 --> 00:14:18,579
[ TOY SQUEAKS ]
261
00:14:18,580 --> 00:14:21,747
Popescu: WE HAVE THREE
PIGEONS AND TWO PIGEONHOLES.
262
00:14:21,748 --> 00:14:25,453
THEY'LL GO TO THE LEFT, AND
THEY'LL GO TO THE RIGHT.
263
00:14:25,454 --> 00:14:28,922
AT LEAST TWO OF THEM SHOULD
BE IN THE SAME PLACE.
264
00:14:28,923 --> 00:14:32,725
NOW, THE ROAD IS
PRETTY NARROW,
265
00:14:32,726 --> 00:14:37,765
SO EVEN TWO PIGEONS BEING
TOGETHER, IT'S A CROWD.
266
00:14:37,766 --> 00:14:42,236
BEING A CROWD, THEY COLLIDE,
COLLIDE WITH EACH OTHER.
267
00:14:42,237 --> 00:14:46,274
Freeman: BECAUSE THESE PIGEONS
REPRESENT QUANTUM PARTICLES,
268
00:14:46,275 --> 00:14:47,775
SANDU CAN'T ACTUALLY WATCH THEM
269
00:14:47,776 --> 00:14:49,743
AS THEY TRAVEL THROUGH
THE TWO TRACKS.
270
00:14:49,744 --> 00:14:51,478
IF HE DID,
271
00:14:51,479 --> 00:14:56,483
HE WOULD DISRUPT THEIR MOVEMENT
AND RUIN THE EXPERIMENT.
272
00:14:56,484 --> 00:15:01,254
Popescu: WE WANT TO MAKE SURE THAT
WE DO NOT DISTURB THE PARTICLES.
273
00:15:01,255 --> 00:15:03,323
SO WHAT WE HAVE TO DO
274
00:15:03,324 --> 00:15:05,959
IS TO PERFORM THE
EXPERIMENT IN THE DARK.
275
00:15:05,960 --> 00:15:09,595
Freeman: HOWEVER,
SANDU DOES HAVE A WAY
276
00:15:09,596 --> 00:15:12,098
OF CHECKING WHETHER THE
PIGEONS HAVE SHARED A TRACK
277
00:15:12,099 --> 00:15:14,736
WITHOUT DISTURBING
THEIR MOVEMENT.
278
00:15:14,737 --> 00:15:16,538
HE CAN WAIT FOR THEM TO EXIT
279
00:15:16,539 --> 00:15:19,741
AND SEE WHETHER ANY OF THEIR
HATS HAVE FALLEN OFF,
280
00:15:19,742 --> 00:15:22,276
A SURE SIGN OF A COLLISION.
281
00:15:22,277 --> 00:15:24,645
AS WITH EVERYTHING IN
THE QUANTUM WORLD,
282
00:15:24,646 --> 00:15:27,582
THE RESULTS OF THE
EXPERIMENT ARE DIFFERENT
283
00:15:27,583 --> 00:15:29,849
EVERY TIME IT IS RUN.
284
00:15:29,850 --> 00:15:34,589
I THROWED THE THREE PARTICLES
EXACTLY IN THE SAME WAY.
285
00:15:34,590 --> 00:15:37,958
SOMETIMES I SEE HATS.
SOMETIMES I DO NOT.
286
00:15:37,959 --> 00:15:41,728
Freeman: BUT ONE ASPECT OF THE
EXPERIMENT SEEMED TO FLY IN THE FACE
287
00:15:41,729 --> 00:15:45,299
OF THOSE QUANTUM MECHANICAL
RULES OF RANDOMNESS.
288
00:15:45,300 --> 00:15:49,368
WHENEVER THE PIGEONS EXIT
TOGETHER ON ONE SIDE,
289
00:15:49,369 --> 00:15:53,007
SANDU FINDS THEY ARE
ALWAYS WEARING HATS.
290
00:15:53,008 --> 00:15:57,044
TWO PIGEONS MUST HAVE
GONE DOWN THE SAME TRACK,
291
00:15:57,045 --> 00:16:01,281
AND, AS IF BY MAGIC,
THEY DID NOT COLLIDE.
292
00:16:01,282 --> 00:16:04,618
HOWEVER, IF INSTEAD
293
00:16:04,619 --> 00:16:07,888
SANDU CHECKS ON THE PIGEONS
RIGHT BEFORE THE FORK,
294
00:16:07,889 --> 00:16:09,989
HE SEES SOMETHING DIFFERENT.
295
00:16:09,990 --> 00:16:13,026
SOMETIMES HE FINDS ALL THREE
OF THEM WEARING THEIR HATS,
296
00:16:13,027 --> 00:16:18,132
AND SOMETIMES TWO OF THEM
HAVE LOST THEIR HATS.
297
00:16:18,133 --> 00:16:20,666
Popescu: IF I CHECK
THEM BEFORE THE FORK,
298
00:16:20,667 --> 00:16:25,705
THERE WERE TWO POSSIBILITIES OF
EVENTS THAT HAPPENED EARLIER,
299
00:16:25,706 --> 00:16:29,743
NAMELY, HATS WERE LOST
OR HATS WERE NOT LOST.
300
00:16:29,744 --> 00:16:34,480
IF, ON THE OTHER HAND, I CHECK
THE PIGEONS ONLY LATER,
301
00:16:34,481 --> 00:16:37,818
I SEE THAT ONE OF THESE
POSSIBILITIES DISAPPEAR.
302
00:16:37,819 --> 00:16:39,319
THE QUESTION IS,
303
00:16:39,320 --> 00:16:44,058
HOW CAN MY DECISION OF EITHER
CHECKING HERE OR CHECKING THERE
304
00:16:44,059 --> 00:16:47,661
MAKE ONE EARLIER
POSSIBILITY DISAPPEAR?
305
00:16:47,662 --> 00:16:52,199
Freeman: SANDU BELIEVES THE MOST NATURAL
EXPLANATION FOR WHAT'S HAPPENING
306
00:16:52,200 --> 00:16:54,667
IS THAT INFORMATION
FROM THE FUTURE
307
00:16:54,668 --> 00:16:57,371
TRAVELS BACKWARD THROUGH TIME.
308
00:16:57,372 --> 00:17:00,406
WHILE THE PIGEONS ARE
STILL INSIDE THE TRACKS,
309
00:17:00,407 --> 00:17:03,945
THEY APPEAR TO ALREADY KNOW
THAT SANDU IS GOING TO WAIT
310
00:17:03,946 --> 00:17:08,181
AND CHECK ON THEM ONLY
AFTER THEY HAVE EXITED,
311
00:17:08,182 --> 00:17:12,452
AND SO THEY DON'T COLLIDE.
312
00:17:12,453 --> 00:17:16,122
WE NEED TO CONCLUDE THAT, NO
MATTER HOW STRANGE THIS MAY BE,
313
00:17:16,123 --> 00:17:18,558
NO MATTER HOW UNUSUAL,
314
00:17:18,559 --> 00:17:21,595
MOST PROBABLY WHAT HAPPENS IS
315
00:17:21,596 --> 00:17:25,433
THAT THE FUTURE DOES
INFLUENCE THE PAST.
316
00:17:27,035 --> 00:17:29,536
YOU'VE HEARD THE EXPRESSION
317
00:17:29,537 --> 00:17:33,007
"LIFE IS LIKE A BOX
OF CHOCOLATES."
318
00:17:33,008 --> 00:17:35,142
THERE ARE SO MANY POSSIBILITIES,
319
00:17:35,143 --> 00:17:37,276
YOU NEVER KNOW WHAT
YOU'RE GOING TO GET.
320
00:17:37,277 --> 00:17:41,515
BUT THE POSSIBILITIES MAY NOT
BE AS GREAT AS WE THINK.
321
00:17:41,516 --> 00:17:47,855
THE FUTURE COULD BE REACHING
BACK AND STEALING SOME.
322
00:17:48,890 --> 00:17:52,758
IN FACT, THE FUTURE OF
THE ENTIRE UNIVERSE
323
00:17:52,759 --> 00:17:56,131
COULD BE CONTROLLING
OUR LIVES RIGHT NOW.
324
00:17:58,600 --> 00:18:03,704
WHAT HAS YET TO HAPPEN AFFECTS
WHAT IS HAPPENING NOW.
325
00:18:03,705 --> 00:18:07,910
AT LEAST THAT'S WHAT WE SEE
IN THE SUBATOMIC WORLD.
326
00:18:09,011 --> 00:18:12,047
BUT WE'RE ALL MADE OF ATOMS.
327
00:18:12,048 --> 00:18:14,982
THE ENTIRE UNIVERSE IS.
328
00:18:14,983 --> 00:18:18,420
SO COULD THE ULTIMATE
DESTINY OF THE COSMOS
329
00:18:18,421 --> 00:18:21,924
AFFECT WHAT'S POSSIBLE
IN THE HERE AND NOW?
330
00:18:25,027 --> 00:18:28,596
PROFESSOR PAUL DAVIES
IS A COSMOLOGIST
331
00:18:28,597 --> 00:18:31,098
AT ARIZONA STATE UNIVERSITY.
332
00:18:31,099 --> 00:18:33,701
HE BELIEVES WHAT
HAPPENS IN THE FUTURE
333
00:18:33,702 --> 00:18:35,370
REACHES BACK THROUGH TIME
334
00:18:35,371 --> 00:18:38,108
AND AFFECTS WHAT'S
HAPPENING IN THE PRESENT.
335
00:18:38,109 --> 00:18:41,076
AND WHAT'S HAPPENING NOW
HAS ELIMINATED CHOICES
336
00:18:41,077 --> 00:18:44,378
WE THOUGHT WE COULD
HAVE MADE IN THE PAST.
337
00:18:44,379 --> 00:18:48,450
FOR EXAMPLE, ONCE HIS STUDENTS
STEP FOOT INTO HIS CLASSROOM,
338
00:18:48,451 --> 00:18:51,686
AN EARLIER CHOICE TO DITCH
CLASS IS RULED OUT.
339
00:18:51,687 --> 00:18:53,154
PAUL'S STUDENTS BELIEVE
340
00:18:53,155 --> 00:18:56,691
THEY COULD HAVE SKIPPED TODAY'S
LECTURE IF THEY WANTED TO,
341
00:18:56,692 --> 00:19:00,495
BUT HE THINKS THAT THEY NEVER
ACTUALLY HAD THAT CHOICE.
342
00:19:00,496 --> 00:19:04,266
Davies: WHAT HAPPENS IN THE FUTURE
AND WHAT HAPPENS IN THE PAST
343
00:19:04,267 --> 00:19:06,634
CAN BE LINKED,
344
00:19:06,635 --> 00:19:08,536
SO SOMEHOW,
345
00:19:08,537 --> 00:19:10,404
THE PRESENT KNOWS WHAT'S
GONNA HAPPEN IN THE FUTURE,
346
00:19:10,405 --> 00:19:13,107
AND ALSO WHAT HAPPENS NOW
347
00:19:13,108 --> 00:19:15,743
AFFECTS WHAT COULD HAVE
HAPPENED IN THE PAST.
348
00:19:15,744 --> 00:19:18,546
Freeman: EXPERIMENTS
WITH SUBATOMIC PARTICLES
349
00:19:18,547 --> 00:19:21,383
HAVE ALREADY SHOWN THAT THE
FUTURE POSITION OF AN OBJECT
350
00:19:21,384 --> 00:19:23,951
LIMITS WHERE IT CAN
BE IN THE PRESENT.
351
00:19:23,952 --> 00:19:26,755
PAUL THINKS THE SAME
THING MIGHT BE HAPPENING
352
00:19:26,756 --> 00:19:29,824
AT THE LEVEL OF OUR
EVERYDAY REALITY.
353
00:19:29,825 --> 00:19:32,326
FOR EXAMPLE, AT THE
END OF THE DAY,
354
00:19:32,327 --> 00:19:35,564
PAUL ENJOYS AN ANNIVERSARY
DINNER WITH HIS WIFE.
355
00:19:35,565 --> 00:19:40,567
THAT MEANS THAT CERTAIN EVENTS
EARLIER IN THE DAY CAN'T HAPPEN.
356
00:19:40,568 --> 00:19:42,503
SO, SUPPOSING SOMEBODY WALKS IN
357
00:19:42,504 --> 00:19:45,172
AND OFFERS ME SOME
TICKETS TO A CONCERT.
358
00:19:45,173 --> 00:19:47,208
HEY, PAUL, I GOT
THIS EXTRA TICKET
359
00:19:47,209 --> 00:19:49,243
FOR THIS CONCERT
TONIGHT IN VEGAS,
360
00:19:49,244 --> 00:19:50,478
BUT WE HAVE TO LEAVE,
LIKE, RIGHT NOW.
361
00:19:50,479 --> 00:19:51,846
DO YOU WANT TO COME?
362
00:19:51,847 --> 00:19:55,517
Freeman: COULD PAUL SAY YES
TO THE CONCERT INVITATION?
363
00:19:55,518 --> 00:19:59,788
IF HE DOES, HIS WIFE
WILL BE LEFT ALONE.
364
00:19:59,789 --> 00:20:02,856
HANG ON, LET ME JUST
CHECK MY CALENDAR.
365
00:20:02,857 --> 00:20:06,694
HE MAY FEEL, RIGHT AT THE
MOMENT HE CHECKS HIS CALENDAR,
366
00:20:06,695 --> 00:20:09,463
THAT HE HAS A CHOICE
ABOUT WHAT TO DO.
367
00:20:09,464 --> 00:20:12,366
AM I GONNA HAVE TO MAKE A DECISION
BETWEEN THE CONCERT AND THE DINNER?
368
00:20:12,367 --> 00:20:13,501
WHAT AM I GOING TO DO?
369
00:20:13,502 --> 00:20:16,238
Freeman: BUT HIS
CALENDAR IS IRRELEVANT,
370
00:20:16,239 --> 00:20:19,475
EVEN THOUGH HE DOESN'T
REALIZE IT IN THE PRESENT.
371
00:20:19,476 --> 00:20:23,377
NOT GOING TO THAT DINNER
IS SIMPLY NOT AN OPTION.
372
00:20:23,378 --> 00:20:28,016
MISS IT, AND PAUL'S LIFE
AS HE KNOWS IT IS OVER.
373
00:20:28,017 --> 00:20:30,986
OH, NO. THERE'S SOMETHING I
REALLY CAN'T GET OUT OF.
374
00:20:30,987 --> 00:20:33,721
SORRY, YOU'LL HAVE TO
GIVE IT TO SOMEBODY ELSE.
375
00:20:33,722 --> 00:20:36,224
IT'S NOT THAT HIS
WIFE WILL BE MAD.
376
00:20:36,225 --> 00:20:39,161
PAUL DOES ATTEND THE
DINNER IN THE FUTURE,
377
00:20:39,162 --> 00:20:41,063
AND THAT MAKES IT IMPOSSIBLE
378
00:20:41,064 --> 00:20:43,531
FOR PAUL TO DO ANYTHING
THAT WOULD PREVENT IT.
379
00:20:43,532 --> 00:20:45,299
Davies: I'VE GOT TO DO THIS,
AND I'VE GOT TO DO THAT,
380
00:20:45,300 --> 00:20:46,800
AND HOW DO I CHOOSE
ONE OR THE OTHER?
381
00:20:46,801 --> 00:20:48,568
AND IT TURNS OUT THAT
382
00:20:48,569 --> 00:20:52,074
ALL OF THESE DIFFERENT POSSIBLE
PATHWAYS INTO THE FUTURE
383
00:20:52,075 --> 00:20:54,244
CAN STRAIN OUR FREEDOM
OF ACTION NOW.
384
00:20:54,245 --> 00:20:57,945
Freeman: AND, PAUL BELIEVES,
THIS SAME BACKWARD TIME EFFECT
385
00:20:57,946 --> 00:21:00,248
IS AT PLAY ON A COSMIC SCALE,
386
00:21:00,249 --> 00:21:04,353
FROM THE DISTANT FUTURE TO
THE BEGINNING OF EVERYTHING.
387
00:21:04,354 --> 00:21:07,721
TO HELP MAKE SENSE OF THIS,
388
00:21:07,722 --> 00:21:12,359
IMAGINE OUR UNIVERSE IS
A CHOCOLATE FACTORY.
389
00:21:12,360 --> 00:21:16,163
THE BIG BANG IS THE BEGINNING
OF THE PRODUCTION LINE,
390
00:21:16,164 --> 00:21:18,165
AND THE END OF THE UNIVERSE
391
00:21:18,166 --> 00:21:21,336
IS WHERE THE FINISHED
CHOCOLATES COME OUT.
392
00:21:21,337 --> 00:21:25,038
OUR PRESENT IS
SOMEWHERE IN BETWEEN.
393
00:21:25,039 --> 00:21:29,176
WE MAY THINK WHAT HAPPENS NOW
CHANGES THEIR FINAL STATE,
394
00:21:29,177 --> 00:21:33,448
BUT ACTUALLY, WHAT'S INSIDE
THE FINISHED CHOCOLATES
395
00:21:33,449 --> 00:21:36,750
DETERMINES THE INGREDIENTS
THAT CAN BE PUT IN.
396
00:21:36,751 --> 00:21:40,188
Davies: THERE MAY BE CERTAIN
CHOCOLATE INGREDIENTS
397
00:21:40,189 --> 00:21:43,691
THAT ARE SIMPLY INCONSISTENT
WITH THIS FINAL STATE.
398
00:21:43,692 --> 00:21:46,060
Freeman: IN THE MIDDLE
OF THE PRODUCTION LINE,
399
00:21:46,061 --> 00:21:49,064
IT MAY APPEAR THE MACHINES
CAN ADD A CREAM FILLING
400
00:21:49,065 --> 00:21:50,797
OR A RASPBERRY FILLING,
401
00:21:50,798 --> 00:21:54,669
BUT SINCE THE FINISHED
CHOCOLATES CONTAIN RASPBERRY,
402
00:21:54,670 --> 00:21:58,640
ONLY THE PINK FILLING CAN
POSSIBLY ENTER THE LINE.
403
00:21:58,641 --> 00:22:02,809
THE END LIMITS WHAT
IS POSSIBLE NOW.
404
00:22:02,810 --> 00:22:05,113
AND PAUL THINKS THERE'S A
SIMILAR LIMITING EFFECT
405
00:22:05,114 --> 00:22:07,315
RADIATING BACK TO OUR PRESENT
406
00:22:07,316 --> 00:22:11,318
FROM THE ULTIMATE
FUTURE OF THE UNIVERSE.
407
00:22:11,319 --> 00:22:14,556
Davies: IF WE IMAGINE THE
FINAL STATE OF THE UNIVERSE
408
00:22:14,557 --> 00:22:17,291
BEING FIXED BY
NATURE IN SOME WAY,
409
00:22:17,292 --> 00:22:19,359
THEN THAT WOULD
HAVE IMPLICATIONS
410
00:22:19,360 --> 00:22:22,063
FOR THE PRODUCTION LINE
THAT WE'RE SEEING NOW.
411
00:22:22,064 --> 00:22:25,298
THE BIG DIFFERENCE
WITH THE CHOCOLATES
412
00:22:25,299 --> 00:22:27,367
IS THAT WHATEVER HAPPENS,
413
00:22:27,368 --> 00:22:30,605
THERE WILL BE A FINAL
STATE OF THE CHOCOLATES.
414
00:22:30,606 --> 00:22:33,842
THAT IS DETERMINED IN ADVANCE
BY THE INTERNAL MACHINERY.
415
00:22:33,843 --> 00:22:37,179
BUT IN THE REAL UNIVERSE,
NOBODY, NOT EVEN NATURE,
416
00:22:37,180 --> 00:22:39,747
KNOWS WHAT THAT FINAL
STATE WILL BE.
417
00:22:39,748 --> 00:22:42,817
Freeman: ALTHOUGH NO
ONE CAN SAY FOR SURE,
418
00:22:42,818 --> 00:22:44,385
MOST SCIENTISTS THINK
419
00:22:44,386 --> 00:22:48,655
THE FAR FUTURE OF THE
COSMOS WILL BE COLD, DARK,
420
00:22:48,656 --> 00:22:52,594
AND COMPLETELY EMPTY
OF ALL PARTICLES.
421
00:22:52,595 --> 00:22:55,363
PAUL THINKS WE MIGHT
BE ABLE TO DETECT
422
00:22:55,364 --> 00:22:58,100
THE EFFECTS OF THIS FUTURE
ON CERTAIN EXPERIMENTS
423
00:22:58,101 --> 00:23:00,468
WE PERFORM HERE AND NOW.
424
00:23:00,469 --> 00:23:05,039
ONE IDEA IS TO FIRE A
LASER INTO DEEP SPACE.
425
00:23:05,040 --> 00:23:08,643
AS LONG AS PAUL'S LASER BEAM
EVENTUALLY RUNS INTO SOMETHING,
426
00:23:08,644 --> 00:23:10,478
LIKE A PLANET,
427
00:23:10,479 --> 00:23:12,247
THEN THE LASER WILL
FIRE AS NORMAL.
428
00:23:12,248 --> 00:23:14,548
HOWEVER, IF PAUL
DIRECTS HIS LASER
429
00:23:14,549 --> 00:23:17,050
INTO A COMPLETELY
EMPTY PATCH OF SPACE,
430
00:23:17,051 --> 00:23:19,054
WHERE NOTHING WOULD
EVER BLOCK IT
431
00:23:19,055 --> 00:23:21,355
AND IT COULD, IN THEORY,
TRAVEL FOREVER,
432
00:23:21,356 --> 00:23:24,159
THE LASER MIGHT NOT WORK.
433
00:23:24,160 --> 00:23:27,062
Davies: SO YOU CAN POINT A LASER
AT THE DARK PARTS OF THE SKY,
434
00:23:27,063 --> 00:23:29,697
AND YOU CAN NOTICE THERE
WASN'T ANY LIGHT COMING OUT
435
00:23:29,698 --> 00:23:31,033
OR THERE'S NOT MUCH LIGHT.
436
00:23:31,034 --> 00:23:33,867
Freeman: LIGHT
WOULDN'T COME OUT
437
00:23:33,868 --> 00:23:38,740
BECAUSE NO LIGHT IS ALLOWED IN
THE FAR FUTURE OF THE UNIVERSE.
438
00:23:38,741 --> 00:23:42,477
IF THE END STATE OF THE UNIVERSE
IS, INDEED, DARK AND EMPTY,
439
00:23:42,478 --> 00:23:46,149
NOTHING FROM THE PRESENT, LIKE
PHOTONS FROM THE LASER BEAM,
440
00:23:46,150 --> 00:23:48,683
CAN BE ALLOWED TO REACH IT.
441
00:23:49,852 --> 00:23:54,188
FINDING EVIDENCE THAT THE
FUTURE INFLUENCES THE PRESENT
442
00:23:54,189 --> 00:23:58,159
CREATES AN INTRIGUING
POSSIBILITY.
443
00:23:58,160 --> 00:24:04,200
CAN WE, RIGHT NOW, REACH BACK
AND AFFECT OUR OWN PAST?
444
00:24:08,838 --> 00:24:14,943
QUANTUM MECHANICS SUGGESTS THE
FUTURE CAN CONTROL THE PAST.
445
00:24:14,944 --> 00:24:19,949
MAYBE SOME DAY, WE'LL TURN
THEORY INTO PRACTICE,
446
00:24:19,950 --> 00:24:21,418
BUT WHAT ARE THE LIMITS?
447
00:24:21,419 --> 00:24:25,954
COULD SOMEONE GO BACK IN
TIME AND CHANGE HISTORY,
448
00:24:25,955 --> 00:24:32,060
STOP HITLER BEFORE
HE STARTS A WAR
449
00:24:32,061 --> 00:24:38,167
OR SAVE JFK FROM AN
ASSASSIN'S BULLET?
450
00:24:40,904 --> 00:24:43,972
TODD BRUN LIKES TO IMAGINE
WHAT IT WOULD BE LIKE
451
00:24:43,973 --> 00:24:45,907
TO LIVE IN THE PAST.
452
00:24:45,908 --> 00:24:49,245
AND AS A PROFESSOR OF PHYSICS
AND ELECTRICAL ENGINEERING
453
00:24:49,246 --> 00:24:52,347
AT THE UNIVERSITY OF
SOUTHERN CALIFORNIA,
454
00:24:52,348 --> 00:24:53,982
HE'S ACTUALLY TRYING TO WORK OUT
455
00:24:53,983 --> 00:24:56,318
WHETHER TRAVELING BACK
IN TIME IS POSSIBLE.
456
00:24:57,787 --> 00:25:01,490
Brun: THE DIRECTION OF TIME
ITSELF IS SOMETHING OF A MYSTERY.
457
00:25:01,491 --> 00:25:04,594
IN THE EQUATIONS OF
PHYSICS, IT SEEMS LIKE
458
00:25:04,595 --> 00:25:06,795
YOU COULD RUN THEM EITHER
FORWARDS OR BACKWARDS.
459
00:25:06,796 --> 00:25:09,966
Freeman: BUT EVERYTHING WE
OBSERVE IN THE WORLD AROUND US
460
00:25:09,967 --> 00:25:15,037
POINTS TO TIME HAVING ONLY ONE
POSSIBLE DIRECTION ... FORWARDS.
461
00:25:15,038 --> 00:25:19,307
EVERYTHING GROWS OLDER,
EVERYTHING DECAYS.
462
00:25:19,308 --> 00:25:21,977
Brun: WHEN WE WRITE
ON A CHALKBOARD,
463
00:25:21,978 --> 00:25:24,779
THE MARKS THAT WE
LEAVE ARE CHALK DUST
464
00:25:24,780 --> 00:25:27,482
THAT CRUMBLES OFF OF THE
END OF OUR STICK OF CHALK
465
00:25:27,483 --> 00:25:29,451
AND STICKS TO THE BOARD.
466
00:25:29,452 --> 00:25:31,819
IF I MOVE MY STICK OF
CHALK OVER A CHALKBOARD,
467
00:25:31,820 --> 00:25:33,756
THE DUST THAT
CRUMBLED OFF THE END
468
00:25:33,757 --> 00:25:36,159
DOESN'T, ONCE AGAIN, ADHERE
TO MY STICK OF CHALK
469
00:25:36,160 --> 00:25:38,527
AND MAKE IT A LONGER
STICK OF CHALK.
470
00:25:38,528 --> 00:25:40,729
THAT'S THE ARROW
OF TIME AT WORK.
471
00:25:40,730 --> 00:25:44,299
Freeman: HOWEVER, IF TIME
IS REALLY A DIMENSION,
472
00:25:44,300 --> 00:25:48,970
AS EINSTEIN SAYS, TIME
THAT'S PASSED STILL EXISTS.
473
00:25:48,971 --> 00:25:51,172
IT'S SIMPLY LOCATED
SOMEWHERE ELSE
474
00:25:51,173 --> 00:25:53,509
IN THE FORWARD
DIMENSIONAL UNIVERSE.
475
00:25:53,510 --> 00:25:59,181
Brun: SPACE TIME IS THE ENTIRE
FOUR DIMENSIONAL BACKGROUND
476
00:25:59,182 --> 00:26:01,784
FOR EVERYTHING THAT HAPPENS
AND EVER HAS HAPPENED
477
00:26:01,785 --> 00:26:03,853
AND EVER WILL HAPPEN
IN THE UNIVERSE.
478
00:26:03,854 --> 00:26:09,090
Freeman: EVENTS IN OUR PAST MAY
NOT BE GONE FROM THE UNIVERSE,
479
00:26:09,091 --> 00:26:11,259
BUT THEY ARE OUT OF REACH.
480
00:26:11,260 --> 00:26:14,028
IF YOU TRAVEL FASTER
THAN THE SPEED OF LIGHT,
481
00:26:14,029 --> 00:26:16,231
EINSTEIN'S EQUATIONS
OF RELATIVITY
482
00:26:16,232 --> 00:26:19,101
SAY YOUR TIME TICKS BACKWARDS.
483
00:26:19,102 --> 00:26:22,773
THE TROUBLE IS, IT TAKES AN
INFINITE AMOUNT OF ENERGY
484
00:26:22,774 --> 00:26:24,973
TO REACH THE SPEED OF LIGHT,
485
00:26:24,974 --> 00:26:27,476
SO YOU CAN FORGET THAT.
486
00:26:27,477 --> 00:26:30,512
BUT THERE MAY BE WAYS
TO GET TO THE PAST.
487
00:26:30,513 --> 00:26:33,915
THEY'RE CALLED CLOSED
TIME LIGHT CURVES,
488
00:26:33,916 --> 00:26:37,786
STRANGE DISTORTIONS OF
THE FABRIC OF SPACE TIME
489
00:26:37,787 --> 00:26:42,258
THAT COULD GIVE YOU A SHORTCUT
TO A DIFFERENT MOMENT IN TIME.
490
00:26:42,259 --> 00:26:46,028
SOME VERY EXOTIC ARRANGEMENTS
OF MATTER IN SPACE TIME
491
00:26:46,029 --> 00:26:49,498
CAN CAUSE THESE PATHS TO
ACTUALLY CURVE SO MUCH,
492
00:26:49,499 --> 00:26:52,236
THEY CURVE ALL THE WAY
AROUND BACK UPON THEMSELVES.
493
00:26:52,237 --> 00:26:53,701
HOWDY.
494
00:26:53,702 --> 00:26:55,403
Freeman: TIME TRAVELING TODD
495
00:26:55,404 --> 00:26:57,772
WOULDN'T HAVE TO TRAVEL
FASTER THAN LIGHT.
496
00:26:57,773 --> 00:27:00,275
AS HE MOVES FORWARD,
THE FOLD IN SPACE TIME
497
00:27:00,276 --> 00:27:03,179
WOULD CARRY HIM BACKWARD
TO THE SAME POINT IN SPACE
498
00:27:03,180 --> 00:27:05,113
BUT AT AN EARLIER TIME.
499
00:27:05,114 --> 00:27:09,285
Brun: THIS IS NOT THE SITUATION
THAT WE NORMALLY OBSERVE
500
00:27:09,286 --> 00:27:11,053
IN THE UNIVERSE,
501
00:27:11,054 --> 00:27:13,523
BUT PEOPLE CAN SOLVE
EINSTEIN'S EQUATIONS
502
00:27:13,524 --> 00:27:14,957
AND FIND THESE SOLUTIONS
503
00:27:14,958 --> 00:27:17,592
THAT CONTAIN THESE CLOSED
TIME LIGHT CURVES.
504
00:27:17,593 --> 00:27:21,931
Freeman: THE LAWS OF PHYSICS SAY
WE CAN VISIT A POINT IN THE PAST.
505
00:27:21,932 --> 00:27:25,634
THERE'S NOTHING STOPPING TODD
VISITING ONE OF HIS ANCESTORS
506
00:27:25,635 --> 00:27:29,306
AND EXPLAINING HOW HE MANAGED
TO JUMP BACK IN TIME.
507
00:27:31,173 --> 00:27:33,575
YOU MIGHT FIND
THIS INTERESTING.
508
00:27:33,576 --> 00:27:38,145
HOWEVER, TODD THINKS IT'S
IMPOSSIBLE TO ALTER THE PAST.
509
00:27:38,146 --> 00:27:42,451
TODD'S ANCESTOR MUST ALWAYS
HAVE RECEIVED A VISITOR
510
00:27:42,452 --> 00:27:45,787
FROM THE FUTURE.
511
00:27:45,788 --> 00:27:48,024
Brun: THE HISTORY OF
A SINGLE UNIVERSE
512
00:27:48,025 --> 00:27:50,425
CAN ONLY CONTAIN ONE
SET OF ACTIONS.
513
00:27:50,426 --> 00:27:51,961
THINGS THAT ARE INCOMPATIBLE,
514
00:27:51,962 --> 00:27:54,229
THINGS THAT ARE ACTUAL
INCONSISTENCIES
515
00:27:54,230 --> 00:27:55,933
SHOULD NOT BE ALLOWED.
516
00:27:58,969 --> 00:28:01,705
Freeman: ANYTHING THE
TIME TRAVELER DOES
517
00:28:01,706 --> 00:28:04,472
MUST FIT IN WITH WHAT'S
ALREADY HAPPENED.
518
00:28:04,473 --> 00:28:07,843
FOR EXAMPLE, LET'S SAY
TODD IS A TIME TRAVELER
519
00:28:07,844 --> 00:28:10,545
WHO HOPES TO ALTER
SOME PAST EVENT,
520
00:28:10,546 --> 00:28:14,849
AND IMAGINE THAT EVENT IS A
DANCE TODD WANTS TO STOP.
521
00:28:14,850 --> 00:28:17,952
Brun: THE PAST HAS
TO BE CONSISTENT,
522
00:28:17,953 --> 00:28:20,689
SO IF I GO INTO THE
MIDDLE OF THE DANCE
523
00:28:20,690 --> 00:28:22,225
AND I TRY TO DISRUPT IT
524
00:28:22,226 --> 00:28:25,394
BY PULLING A DANCER OUT
OF THE FLOW OF THE DANCE,
525
00:28:25,395 --> 00:28:28,730
THEN IT WILL HAVE TO
BE THAT THAT DANCER
526
00:28:28,731 --> 00:28:31,732
LEFT THE DANCE AT
THAT VERY MOMENT.
527
00:28:31,733 --> 00:28:35,970
Freeman: NO MATTER WHAT TODD DOES,
HE WILL ONLY FULFILL EVENTS
528
00:28:35,971 --> 00:28:40,009
AND SEQUENCES THAT HAVE
ALREADY TAKEN PLACE.
529
00:28:40,010 --> 00:28:43,077
Brun: IF I TRY TO GO AND JUMP
INTO THE MIDDLE OF A DANCE
530
00:28:43,078 --> 00:28:44,913
THAT'S ALREADY HAPPENING,
531
00:28:44,914 --> 00:28:47,583
THEN IT HAS TO HAVE
BEEN THAT, IN THE PAST,
532
00:28:47,584 --> 00:28:51,420
IF I MYSTERIOUSLY APPEARED AT
THAT POINT AND JOINED THE SET.
533
00:28:51,421 --> 00:28:54,021
EITHER THE DANCE WAS
ALWAYS DISRUPTED
534
00:28:54,022 --> 00:28:56,659
AND I'M JUST FULFILLING
WHAT ALREADY HAPPENED,
535
00:28:56,660 --> 00:28:59,661
OR IF THE DANCE TOOK PLACE,
536
00:28:59,662 --> 00:29:02,498
THEN MY ATTEMPTS TO DISRUPT
IT WILL BE FUTILE.
537
00:29:02,499 --> 00:29:05,933
Freeman: IT'S AS IF THE UNIVERSE
HAS A BUILT IN SAFEGUARD
538
00:29:05,934 --> 00:29:08,636
TO KEEP ITS HISTORY CONSISTENT.
539
00:29:08,637 --> 00:29:12,442
YOU SIMPLY CAN'T KILL
YOUR OWN GRANDFATHER.
540
00:29:15,779 --> 00:29:19,547
BUT THERE IS ONE PARADOX
THAT TIME TRAVEL MAY CREATE.
541
00:29:19,548 --> 00:29:23,484
WHEN TIME TRAVELING TODD TURNS
OVER THOSE TIME MACHINE PLANS
542
00:29:23,485 --> 00:29:24,786
TO HIS ANCESTOR...
543
00:29:24,787 --> 00:29:26,456
YOU MIGHT FIND
THIS INTERESTING.
544
00:29:26,457 --> 00:29:30,459
...THAT ANCESTOR COULD
THEN PASS DOWN THOSE PLANS
545
00:29:30,460 --> 00:29:32,760
BACK TO TIME TRAVELING TODD,
546
00:29:32,761 --> 00:29:37,633
WHO USES THE PLANS TO
BUILD THE TIME MACHINE.
547
00:29:37,634 --> 00:29:42,304
NEITHER OF THEM ACTUALLY
CREATED THE PLANS.
548
00:29:42,305 --> 00:29:45,408
Brun: THE QUESTION IS, WHERE
DID THE PLANS COME FROM?
549
00:29:45,409 --> 00:29:47,643
THE PLANS SEEMINGLY
APPEARED OUT OF NOWHERE.
550
00:29:47,644 --> 00:29:50,813
Freeman: THIS IS THE KIND OF
PARADOX THAT CRITICS CITE
551
00:29:50,814 --> 00:29:53,414
TO QUASH THE IDEA
OF TIME TRAVEL.
552
00:29:53,415 --> 00:29:56,050
AND YET, TODD'S
CALCULATIONS SHOW
553
00:29:56,051 --> 00:29:59,288
THAT TIME TRAVEL CAN
ACTUALLY CAUSE INFORMATION
554
00:29:59,289 --> 00:30:01,557
TO APPEAR FROM NOTHING.
555
00:30:01,558 --> 00:30:03,759
Brun: IN SOME OF THE
MATHEMATICAL MODELS
556
00:30:03,760 --> 00:30:06,394
THAT WE'VE DEVELOPED FOR
CLOSED TIME LIGHT CURVES,
557
00:30:06,395 --> 00:30:10,899
YOU CAN FORCE THE UNIVERSE
TO COUGH UP INFORMATION
558
00:30:10,900 --> 00:30:13,169
WITHOUT EVER HAVING
CALCULATED IT.
559
00:30:13,170 --> 00:30:17,472
Freeman: TODD SAYS A UNIVERSE
WHERE MOVING BACKWARD IN TIME
560
00:30:17,473 --> 00:30:18,641
IS POSSIBLE
561
00:30:18,642 --> 00:30:21,809
BUT CHANGING THE COURSE
OF HISTORY IS NOT.
562
00:30:21,810 --> 00:30:24,246
HOWEVER, NO ONE HAS
YET COME CLOSE
563
00:30:24,247 --> 00:30:26,114
TO BUILDING A WORKING
TIME MACHINE.
564
00:30:26,115 --> 00:30:30,587
BUT MAYBE TO REACH THE
PAST, WE WON'T NEED ONE.
565
00:30:33,999 --> 00:30:38,169
TRAVELING INTO THE PAST OR
MEETING OUR PRIOR SELVES
566
00:30:38,170 --> 00:30:41,905
REMAINS IN THE REALM
OF SCIENCE FICTION.
567
00:30:41,906 --> 00:30:43,907
BUT MODERN TECHNOLOGY
568
00:30:43,908 --> 00:30:47,778
MAY ALREADY BE BUILDING A
LINK BETWEEN OUR PRESENT...
569
00:30:47,779 --> 00:30:49,982
[ TELEPHONE RINGS ]
570
00:30:52,617 --> 00:30:55,387
...AND OUR PAST SELVES.
571
00:30:56,856 --> 00:30:59,458
HELLO?
572
00:31:02,595 --> 00:31:04,962
TOM WEILER IS A
PHYSICS PROFESSOR
573
00:31:04,963 --> 00:31:07,464
AT VANDERBILT UNIVERSITY.
574
00:31:07,465 --> 00:31:12,368
HE'S HUNTING FOR A
TINY TIME TRAVELER.
575
00:31:12,369 --> 00:31:15,106
IF HE TRACKS IT DOWN,
576
00:31:15,107 --> 00:31:19,809
TOM MAY BE ABLE TO SEND
MESSAGES INTO THE PAST...
577
00:31:19,810 --> 00:31:21,878
[ CELLPHONE BEEPS ]
578
00:31:21,879 --> 00:31:24,682
Woman: YOU HAVE ONE
NEW VOICE MESSAGE.
579
00:31:24,683 --> 00:31:27,051
Weiler: HEY, IT'S ME. YOU LEFT
YOUR WALLET ON THE TABLE.
580
00:31:27,052 --> 00:31:29,686
DON'T FORGET TO PICK IT UP.
581
00:31:29,687 --> 00:31:33,824
...AND RECEIVE COMMUNICATION
FROM THE FUTURE.
582
00:31:33,825 --> 00:31:36,594
TOM'S TARGET IS AN
AS YET UNDISCOVERED
583
00:31:36,595 --> 00:31:40,565
SUBATOMIC PARTICLE CALLED
THE HIGGS SINGLET.
584
00:31:40,566 --> 00:31:43,334
WHEN OUR MOST POWERFUL
PARTICLE ACCELERATOR
585
00:31:43,335 --> 00:31:47,271
CREATES A HIGGS BOSON, ALSO
KNOWN AS THE GOD PARTICLE,
586
00:31:47,272 --> 00:31:50,340
IT MAY NOT BE CREATED ALONE.
587
00:31:50,341 --> 00:31:55,547
THE HIGGS SINGLET MAY BE PART
OF THE SUBATOMIC SHRAPNEL.
588
00:31:55,548 --> 00:31:59,850
HOWEVER, FINDING IT WILL
BE A DIFFICULT TASK.
589
00:31:59,851 --> 00:32:03,721
THE HIGGS SINGLET MAY
QUICKLY ESCAPE OUR REALITY
590
00:32:03,722 --> 00:32:07,091
AND MOVE INTO ANOTHER
DIMENSION OF SPACE.
591
00:32:07,092 --> 00:32:09,660
Weiler: THERE'S SOME
MATHEMATICAL ARGUMENTS
592
00:32:09,661 --> 00:32:12,930
FOR WHY THERE SHOULD BE MORE
THAN THREE SPACE DIMENSIONS.
593
00:32:12,931 --> 00:32:15,433
'CAUSE ALL OF THE PARTICLES
WE HAVE MEASURED UP TO NOW,
594
00:32:15,434 --> 00:32:17,167
THE SO CALLED STANDARD
MODEL PARTICLES,
595
00:32:17,168 --> 00:32:19,537
CANNOT LEAVE OUR THREE
DIMENSIONAL SPACE
596
00:32:19,538 --> 00:32:21,207
AND TRAVEL AN EXTRA DIMENSION.
597
00:32:21,208 --> 00:32:24,674
SO THE HIGGS SINGLET BECOMES
A VERY SPECIAL PARTICLE.
598
00:32:24,675 --> 00:32:27,778
Freeman: TO UNDERSTAND
THE SPECIAL ABILITIES
599
00:32:27,779 --> 00:32:30,780
OF THE HIGGS SINGLET
MORE CLEARLY,
600
00:32:30,781 --> 00:32:32,782
IMAGINE THAT THIS TOY RACETRACK
601
00:32:32,783 --> 00:32:35,252
REPRESENTS THE
DIMENSIONS OF SPACE.
602
00:32:35,253 --> 00:32:39,356
THE FLAT STRAIGHTAWAY SYMBOLIZES
OUR THREE FAMILIAR DIMENSIONS,
603
00:32:39,357 --> 00:32:44,229
AND THE LOOP DE LOOP STANDS
IN FOR AN EXTRA DIMENSION.
604
00:32:44,230 --> 00:32:47,464
ALL PARTICLES WE'VE
DISCOVERED SO FAR
605
00:32:47,465 --> 00:32:50,233
FEEL THE PULL OF ONE OR MORE OF
THREE FUNDAMENTAL FORCES ...
606
00:32:50,234 --> 00:32:52,502
ELECTROMAGNETISM,
607
00:32:52,503 --> 00:32:56,240
THE STRONG FORCE,
AND THE WEAK FORCE.
608
00:32:56,241 --> 00:33:00,211
WHICH FORCE OR FORCES A PARTICLE
FEELS DEPENDS ON ITS CHARGE.
609
00:33:00,212 --> 00:33:03,314
IT MAY HAVE AN ELECTRIC
CHARGE, A WEAK CHARGE,
610
00:33:03,315 --> 00:33:07,352
OR A CHARGE THAT MAKES YOU
FEEL THE STRONG FORCE.
611
00:33:07,353 --> 00:33:11,622
WE HAVE NOT YET FOUND A
PARTICLE THAT HAS NO CHARGE.
612
00:33:11,623 --> 00:33:14,692
Weiler: SO, WHEN WE LOOK
AT A NORMAL PARTICLE,
613
00:33:14,693 --> 00:33:17,962
BECAUSE THE PARTICLE CARRIES
SOME KIND OF CHARGE,
614
00:33:17,963 --> 00:33:21,298
THAT CHARGES STICKS IT
TO THE THREE DIMENSIONS.
615
00:33:21,299 --> 00:33:25,070
AND THAT'S THE EXAMPLE THAT'S
GIVEN BY THIS GREEN CAR.
616
00:33:27,405 --> 00:33:31,209
Freeman: BECAUSE NORMAL PARTICLES
REMAIN TIED TO OUR THREE DIMENSIONS,
617
00:33:31,210 --> 00:33:33,946
THEY CAN TRAVEL ONLY
ONE WAY THROUGH TIME.
618
00:33:33,947 --> 00:33:37,347
BUT TOM BELIEVES A HIGGS
SINGLET IS DIFFERENT ...
619
00:33:37,348 --> 00:33:39,316
IT HAS NO CHARGE WHATSOEVER.
620
00:33:39,317 --> 00:33:41,152
IT'S CALLED A SINGLET
621
00:33:41,153 --> 00:33:45,189
BECAUSE IT ONLY FEELS A
SINGLE FORCE ... GRAVITY.
622
00:33:45,190 --> 00:33:50,027
AND THAT MEANS IT'S FREE TO
STRAY FROM THE USUAL PATH.
623
00:33:50,028 --> 00:33:52,863
TOM SUSPECTS A HIGGS
SINGLET MAY TRAVEL
624
00:33:52,864 --> 00:33:56,802
TO AN EXTRA DIMENSION OF SPACE
THAT CURLS BACK ON ITSELF.
625
00:33:56,803 --> 00:33:59,604
HE CALLS IT THE "U" DIMENSION.
626
00:33:59,605 --> 00:34:02,607
Weiler: SO THE "U" DIMENSION
IS VERY, VERY SMALL.
627
00:34:02,608 --> 00:34:04,575
THE HIGGS SINGLET PERCEIVES
THE EXTRA DIMENSION,
628
00:34:04,576 --> 00:34:08,111
WHICH IN THIS TOY MODEL,
IS THE LOOP THAT WE SEE.
629
00:34:08,112 --> 00:34:11,314
Freeman: AS THE HIGGS
SINGLET ENTERS THE LOOP,
630
00:34:11,315 --> 00:34:15,653
IT'S MOMENTARILY MOVING AGAINST
THE NORMAL ONE WAY FLOW OF TIME.
631
00:34:15,654 --> 00:34:16,953
Weiler: IF I LOOK AT TIME,
632
00:34:16,954 --> 00:34:20,124
WHICH EINSTEIN TOLD US IS
JUST ANOTHER COORDINATE,
633
00:34:20,125 --> 00:34:22,292
THERE'S NOTHING
FUNDAMENTAL TO HIS THEORY
634
00:34:22,293 --> 00:34:25,796
THAT SAYS YOU CAN'T HAVE
TIME GROWING NEGATIVE.
635
00:34:25,797 --> 00:34:28,633
THE HIGGS PARTICLE, IT'LL
TRAVEL THROUGH POSITIVE TIME,
636
00:34:28,634 --> 00:34:31,569
AND IN THIS DIRECTION, IT'LL
TRAVEL THROUGH NEGATIVE TIME,
637
00:34:31,570 --> 00:34:33,872
AND THEN IT'LL TRAVEL THROUGH
POSITIVE TIME AGAIN.
638
00:34:33,873 --> 00:34:35,906
IT LOOKS LIKE IT HAS TO
GO AN EXTRA DISTANCE
639
00:34:35,907 --> 00:34:38,542
AND, THEREFORE, TAKE AN EXTRA
TIME TO GET TO THE END POINT,
640
00:34:38,543 --> 00:34:42,347
BUT, IN FACT, IF IN THE EXTRA
DIMENSION, TIME RUNS BACKWARDS,
641
00:34:42,348 --> 00:34:46,017
THEN IT'S GAINING TIME EACH
TIME IT GOES AROUND THIS LOOP.
642
00:34:46,018 --> 00:34:51,221
Freeman: AND THAT GIVES A
CLUE FOR HOW TO FIND IT.
643
00:34:51,222 --> 00:34:54,325
THE WORLD'S MOST POWERFUL
PARTICLE ACCELERATOR,
644
00:34:54,326 --> 00:34:57,729
THE LARGE HADRON
COLLIDER IN SWITZERLAND,
645
00:34:57,730 --> 00:35:01,865
FIRES PROTONS AT ONE ANOTHER
AT ALMOST THE SPEED OF LIGHT.
646
00:35:01,866 --> 00:35:05,435
THEIR COLLISIONS CREATE
SHOWERS OF SUBATOMIC DEBRIS,
647
00:35:05,436 --> 00:35:08,740
PARTICLES THAT LIVE JUST
A FRACTION OF A SECOND
648
00:35:08,741 --> 00:35:11,075
BEFORE POPPING OUT OF EXISTENCE.
649
00:35:11,076 --> 00:35:14,211
TOM SUSPECTS THAT ONE
OF THESE PARTICLES
650
00:35:14,212 --> 00:35:17,147
COULD BE HIS MYSTERIOUS
TIME TRAVELER.
651
00:35:17,148 --> 00:35:20,785
BUT TO FIND THE BACKWARDS IN
TIME TRAVELING HIGGS SINGLET,
652
00:35:20,786 --> 00:35:23,088
WE'LL HAVE TO LOOK
AT WHAT HAPPENS
653
00:35:23,089 --> 00:35:25,589
BEFORE THE COLLISION
THAT CREATED IT.
654
00:35:25,590 --> 00:35:28,191
WE'RE SCATTERING THE
PARTICLE BEFORE,
655
00:35:28,192 --> 00:35:32,062
ACCORDING TO THE TIME ON OUR
CLOCKS, BEFORE IT WAS PRODUCED.
656
00:35:32,063 --> 00:35:36,466
Freeman: CURRENTLY, THE L.H.C.
ISN'T SET UP
657
00:35:36,467 --> 00:35:39,736
TO LOOK AT COLLISIONS
BEFORE THEY HAPPEN.
658
00:35:39,737 --> 00:35:43,807
ONE OF THE STANDARD PROTOCOLS
IS THAT DECAY OF RECOLLISIONS
659
00:35:43,808 --> 00:35:47,977
DON'T HAPPEN BEFORE THE
PARTICLE IS PRODUCED.
660
00:35:47,978 --> 00:35:52,517
Freeman: UNWITTINGLY, WE MAY
BE CREATING HIGGS SINGLETS,
661
00:35:52,518 --> 00:35:55,953
AND TOM BELIEVES HIS
MYSTERIOUS PARTICLE
662
00:35:55,954 --> 00:36:00,591
COULD EVENTUALLY LEAD
US BACKWARD IN TIME.
663
00:36:00,592 --> 00:36:04,928
Weiler: WELL, IF YOU COULD CONTROL
THIS THING, YOU COULD, AT A MINIMUM,
664
00:36:04,929 --> 00:36:07,765
SEND THE PARTICLES
AS MORSE CODE.
665
00:36:07,766 --> 00:36:10,435
YOU COULD SEND A
SIGNAL TO THE PAST.
666
00:36:10,436 --> 00:36:14,337
Freeman: YOU COULD EVEN USE IT TO
SEND YOUR YOUNGER SELF A MESSAGE.
667
00:36:14,338 --> 00:36:15,939
HEY, THIS IS ME.
668
00:36:15,940 --> 00:36:17,941
YOU LEFT YOUR
WALLET ON THE TABLE.
669
00:36:17,942 --> 00:36:19,410
DON'T FORGET TO PICK IT UP.
670
00:36:19,411 --> 00:36:24,515
COMMUNICATION LINKS INTO THE
PAST MAY ALREADY EXIST,
671
00:36:24,516 --> 00:36:26,984
AND THIS THEORETICAL PHYSICIST
672
00:36:26,985 --> 00:36:30,020
THINKS HE'S FIGURED OUT
WHAT IT TAKES TO MAKE ONE.
673
00:36:30,021 --> 00:36:34,426
CAN WE, IN FACT, BUILD
A TIME MACHINE?
674
00:36:38,999 --> 00:36:41,934
I WOULD LOVE TO
HAVE A TIME MACHINE
675
00:36:41,935 --> 00:36:45,538
TO BE ABLE TO RELIVE
TREASURED MOMENTS
676
00:36:45,539 --> 00:36:50,009
OR MAYBE TO HAVE A CHANCE
TO DO SOME THINGS OVER.
677
00:36:50,010 --> 00:36:56,651
TIME TRAVEL COULD BE POSSIBLE
WITH THE HELP OF A WORMHOLE...
678
00:36:58,519 --> 00:37:03,491
...A COSMIC SHORTCUT
THROUGH SPACE AND TIME.
679
00:37:03,492 --> 00:37:06,759
NO ONE HAS EVER SEEN A WORMHOLE,
680
00:37:06,760 --> 00:37:12,367
SO MAYBE WE'LL JUST
HAVE TO BUILD ONE.
681
00:37:15,336 --> 00:37:17,670
LUKE BUTCHER IS A
THEORETICAL PHYSICIST
682
00:37:17,671 --> 00:37:20,907
WITH THE UNIVERSITY OF
EDINBURGH IN SCOTLAND.
683
00:37:20,908 --> 00:37:24,578
HE STUDIES DISTORTIONS
OF SPACE TIME,
684
00:37:24,579 --> 00:37:26,880
HOW ENERGY WARPS THE
FABRIC OF THE UNIVERSE.
685
00:37:26,881 --> 00:37:28,782
Butcher: EINSTEIN'S EQUATIONS,
686
00:37:28,783 --> 00:37:33,719
OUR RELATION BETWEEN THE ENERGY
AND MATTER OF THE UNIVERSE
687
00:37:33,720 --> 00:37:36,288
AND THE CURVATURE THAT
THAT MATTER CAUSES.
688
00:37:36,289 --> 00:37:39,592
YOU GO FROM A FLAT THING,
YOU PUT SOME ENERGY IN,
689
00:37:39,593 --> 00:37:41,760
AND EINSTEIN SAYS THAT
THE SPACE WILL CURVE.
690
00:37:41,761 --> 00:37:44,431
AND THE MORE ENERGY YOU PUT
IN, THE MORE CURVED IT GETS.
691
00:37:44,432 --> 00:37:49,103
Freeman: WORMHOLES ARE EXTREME
DISTORTIONS IN SPACE TIME.
692
00:37:49,104 --> 00:37:53,940
THEY CAN, THEORETICALLY, LINK
TWO DIFFERENT POINTS IN SPACE
693
00:37:53,941 --> 00:37:56,342
AND TWO DIFFERENT
POINTS IN TIME.
694
00:37:56,343 --> 00:37:59,445
Butcher: SO WORMHOLES
HAVE NOT BEEN OBSERVED,
695
00:37:59,446 --> 00:38:01,449
BUT WE CAN STUDY
THEM MATHEMATICALLY.
696
00:38:01,450 --> 00:38:04,751
IF YOU WRITE DOWN THE SHAPE YOU
THINK SPACE TIME MIGHT BE,
697
00:38:04,752 --> 00:38:07,020
THEN YOU CAN PUT THEM INTO
EINSTEIN'S EQUATIONS.
698
00:38:07,021 --> 00:38:08,889
AND WHAT THOSE EQUATIONS
WILL SPIT OUT
699
00:38:08,890 --> 00:38:10,791
IS THE SORTS OF ENERGY YOU NEED
700
00:38:10,792 --> 00:38:13,662
FOR THAT SPACE TIME TO
EXIST AND TO BE STABLE.
701
00:38:16,631 --> 00:38:19,433
Freeman: LUKE STARTED
CALCULATING WHAT IT WOULD TAKE
702
00:38:19,434 --> 00:38:22,335
TO WARP A PATCH OF SPACE
TIME INTO A WORMHOLE
703
00:38:22,336 --> 00:38:24,170
SOMEONE COULD TRAVEL THROUGH.
704
00:38:24,171 --> 00:38:29,275
IT NEEDS A PARTICULAR FORM OF
ENERGY CALLED NEGATIVE ENERGY.
705
00:38:29,276 --> 00:38:33,547
Butcher: SO, THE BEST WAY OF THINKING
ABOUT WHAT NEGATIVE ENERGY IS
706
00:38:33,548 --> 00:38:36,516
IS TO THINK ABOUT
WHAT ZERO ENERGY IS.
707
00:38:36,517 --> 00:38:38,451
ZERO ENERGY IS THE VACUUM.
708
00:38:38,452 --> 00:38:41,922
Freeman: BUT THE VACUUM
IS NOT TRULY EMPTY.
709
00:38:41,923 --> 00:38:44,791
IT'S FILLED WITH
QUANTUM PARTICLES
710
00:38:44,792 --> 00:38:48,462
POPPING IN AND OUT OF EXISTENCE.
711
00:38:48,463 --> 00:38:50,396
IF WE CAN GET RID OF SOME OF
THOSE QUANTUM FLUCTUATIONS,
712
00:38:50,397 --> 00:38:52,533
WE'LL END UP WITH
NEGATIVE ENERGY.
713
00:38:54,501 --> 00:38:56,637
Freeman: SCIENTISTS HAVE
BEEN ABLE TO CREATE
714
00:38:56,638 --> 00:38:59,539
SMALL DOSES OF NEGATIVE
ENERGY IN THE LAB.
715
00:38:59,540 --> 00:39:03,009
THEY PLACE TWO CONDUCTING
PLATES VERY CLOSE TOGETHER
716
00:39:03,010 --> 00:39:05,646
TO CONSTRAIN THE
QUANTUM FLUCTUATIONS
717
00:39:05,647 --> 00:39:07,713
IN THE GAP BETWEEN THEM.
718
00:39:07,714 --> 00:39:10,016
BECAUSE THE FLUCTUATIONS INSIDE
719
00:39:10,017 --> 00:39:12,719
ARE WEAKER THAN
THE ONES OUTSIDE,
720
00:39:12,720 --> 00:39:15,021
THE GAP HAS NEGATIVE ENERGY.
721
00:39:15,022 --> 00:39:18,858
IF WE CAN SCALE UP THIS
PROCESS, IT'S POSSIBLE
722
00:39:18,859 --> 00:39:21,795
THAT WE COULD MANUFACTURE
ENOUGH NEGATIVE ENERGY
723
00:39:21,796 --> 00:39:26,366
TO CREATE A WORMHOLE AND USE IT
TO OPEN A WINDOW TO THE PAST.
724
00:39:26,367 --> 00:39:28,101
BUT THERE'S A PROBLEM.
725
00:39:28,102 --> 00:39:29,635
THE MATHEMATICS SAY
726
00:39:29,636 --> 00:39:32,706
THAT WORMHOLES ARE
INCREDIBLY UNSTABLE.
727
00:39:32,707 --> 00:39:37,344
ONCE YOU TRY TO ENTER THEM,
THEY CLOSE RIGHT UP.
728
00:39:37,345 --> 00:39:40,047
Butcher: SO, IF YOU'RE TRYING
TO USE THIS AS A TIME MACHINE
729
00:39:40,048 --> 00:39:42,148
OR A SHORTCUT FROM "A" TO "B,"
730
00:39:42,149 --> 00:39:43,416
THERE'S GONNA BE NO HOPE, RIGHT,
731
00:39:43,417 --> 00:39:44,951
BECAUSE THIS THING'S
GONNA COLLAPSE
732
00:39:44,952 --> 00:39:46,719
BEFORE YOU GET FROM ONE
SIDE TO THE OTHER.
733
00:39:46,720 --> 00:39:49,523
Freeman: BUT AS
LUKE DUG DEEPER,
734
00:39:49,524 --> 00:39:51,659
HE REALIZED THERE MIGHT BE A WAY
735
00:39:51,660 --> 00:39:56,429
TO EXTEND THE LIFE SPAN OF A
WORMHOLE BY SLIMMING IT DOWN.
736
00:39:56,430 --> 00:39:59,032
Butcher: THE INTERESTING THING
ABOUT A WORMHOLE IS THAT
737
00:39:59,033 --> 00:40:01,367
WE HAVE TWO DIFFERENT SORTS
OF CURVATURE GOING ON.
738
00:40:01,368 --> 00:40:04,371
THERE'S THIS LONG,
LONGITUDINAL CURVATURE,
739
00:40:04,372 --> 00:40:07,306
CURVATURE THROUGH THE
WORMHOLE LIKE THIS.
740
00:40:07,307 --> 00:40:10,809
AND THERE'S ALSO CURVATURE
GOING AROUND THE WORMHOLE.
741
00:40:10,810 --> 00:40:13,146
Freeman: A LONGER,
THINNER WORMHOLE
742
00:40:13,147 --> 00:40:16,083
WOULDN'T NEED AS MUCH
NEGATIVE ENERGY TO STAY OPEN,
743
00:40:16,084 --> 00:40:20,387
AND ITS NARROWNESS WOULD
EVEN CREATE SOME OF ITS OWN,
744
00:40:20,388 --> 00:40:23,255
MAKING IT FAR MORE STABLE.
745
00:40:23,256 --> 00:40:26,559
Butcher: ESSENTIALLY, THIS
LONGITUDINAL CURVATURE HERE
746
00:40:26,560 --> 00:40:30,297
NEEDS TO BE BALANCED BY
SOMETHING THAT HOLDS IT IN.
747
00:40:30,298 --> 00:40:32,766
AND SO VERY ROUGHLY SPEAKING,
748
00:40:32,767 --> 00:40:36,503
THE WICKER PATTERN
WEAVED AROUND THIS SIDE
749
00:40:36,504 --> 00:40:39,271
IS ANALOGOUS TO THE ROLE
THAT NEGATIVE ENERGY PLAYS
750
00:40:39,272 --> 00:40:41,242
IN KEEPING THE WORMHOLE STABLE.
751
00:40:41,243 --> 00:40:43,978
Freeman: THE TIGHT
CIRCLES OF SPACE TIME
752
00:40:43,979 --> 00:40:46,313
AROUND THE THROAT
OF THE WORMHOLE
753
00:40:46,314 --> 00:40:48,547
CREATE THEIR OWN NEGATIVE ENERGY
754
00:40:48,548 --> 00:40:51,817
AND KEEP THE PORTAL
PROPPED OPEN.
755
00:40:51,818 --> 00:40:54,020
Butcher: SO, THIS
WORMHOLE, AS YOU CAN SEE,
756
00:40:54,021 --> 00:40:56,288
IS QUITE A LOT
LONGER AND THINNER
757
00:40:56,289 --> 00:40:58,891
THAN THIS WORMHOLE
THAT WE STARTED WITH,
758
00:40:58,892 --> 00:41:00,159
A TYPICAL WORMHOLE.
759
00:41:00,160 --> 00:41:02,829
THIS WORMHOLE, ON
THE OTHER HAND,
760
00:41:02,830 --> 00:41:04,831
IS VERY GENTLY CURVED
FROM TOP TO BOTTOM
761
00:41:04,832 --> 00:41:07,101
AND HAS A VERY TIGHT
CIRCUMFERENCE.
762
00:41:07,102 --> 00:41:09,170
IT REQUIRES LESS NEGATIVE ENERGY
763
00:41:09,171 --> 00:41:10,204
AND GENERATES MORE
NEGATIVE ENERGY,
764
00:41:10,205 --> 00:41:11,840
SO IT SHOULD BE MORE STABLE.
765
00:41:11,841 --> 00:41:15,942
Freeman: LUKE MAY HAVE FIGURED OUT HOW
TO CREATE A MORE STABLE WORMHOLE,
766
00:41:15,943 --> 00:41:19,913
BUT THE QUESTION REMAINS, COULD
IT WORK AS A TIME MACHINE?
767
00:41:19,914 --> 00:41:23,449
Butcher: IT'S ON THE EDGE
OF OUR KNOWLEDGE, REALLY,
768
00:41:23,450 --> 00:41:26,853
BUT IT'S TANTALIZING BECAUSE
IT'S NOT DEFINITIVELY NO,
769
00:41:26,854 --> 00:41:28,723
AND IT'S NOT DEFINITIVELY YES.
770
00:41:28,724 --> 00:41:30,891
IN TERMS OF THE
CALCULATIONS I'VE DONE,
771
00:41:30,892 --> 00:41:32,425
YOU COULD SEND AN OBJECT THROUGH
772
00:41:32,426 --> 00:41:34,527
MOVING VERY CLOSE TO
THE SPEED OF LIGHT,
773
00:41:34,528 --> 00:41:36,128
AND IT WOULD BE ABLE
TO SQUEEZE THROUGH.
774
00:41:36,129 --> 00:41:39,333
Freeman: LUKE'S
WORMHOLE IS, BY DESIGN,
775
00:41:39,334 --> 00:41:43,036
FAR TOO NARROW FOR A
PERSON TO SQUEEZE THROUGH,
776
00:41:43,037 --> 00:41:46,038
BUT A LIGHT BEAM COULD
PROBABLY MAKE IT.
777
00:41:46,039 --> 00:41:50,277
AND THAT'S ALL WE WOULD NEED TO
SEND A MESSAGE BACK IN TIME.
778
00:41:50,278 --> 00:41:54,114
MAYBE IN THE FUTURE, SOMEONE
WILL DISCOVER A NEW TWIST
779
00:41:54,115 --> 00:41:56,983
THAT ALLOWS A WORMHOLE TO USHER
THROUGH SOMETHING BIGGER,
780
00:41:56,984 --> 00:41:59,855
LIKE A PERSON.
781
00:42:03,189 --> 00:42:06,360
IT MAY SEEM THAT TIME
RELENTLESSLY CARRIES US
782
00:42:06,361 --> 00:42:08,996
FROM THE PAST TOWARD THE FUTURE,
783
00:42:08,997 --> 00:42:13,434
BUT THAT'S NOT THE WAY THE
UNIVERSE REALLY WORKS.
784
00:42:13,435 --> 00:42:15,902
WHAT TAKES PLACE IN OUR PAST
785
00:42:15,903 --> 00:42:19,605
DOES NOT SIMPLY
RECEDE INTO HISTORY.
786
00:42:19,606 --> 00:42:23,909
IT BECOMES IMPRINTED INTO
THE FABRIC OF THE COSMOS.
787
00:42:23,910 --> 00:42:29,315
ONE DAY, WE MAY LEARN TO WEAVE
THE THREADS OF THE PAST
788
00:42:29,316 --> 00:42:31,717
AND THE FUTURE TOGETHER
789
00:42:31,718 --> 00:42:33,753
AND TRULY PLAY
790
00:42:33,754 --> 00:42:36,857
WITH THE BOUNDLESS
POSSIBILITIES OF TIME.
65220
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