1
00:00:02,000 --> 00:00:04,568
THE UNIVERSE WAS BORN TO DIE.

2
00:00:04,569 --> 00:00:08,972
BUT HOW AND WHEN
WILL IT ALL END?

3
00:00:08,973 --> 00:00:10,806
THAT'S THE REASON
I BECAME A COSMOLOGIST.

4
00:00:10,807 --> 00:00:12,543
I WANTED TO BE THE FIRST PERSON
THAT WOULD KNOW

5
00:00:12,544 --> 00:00:14,511
HOW THE UNIVERSE WOULD END.

6
00:00:14,512 --> 00:00:18,282
TWO COSMIC HEAVYWEIGHTS
WRESTLE FOR CONTROL.

7
00:00:18,283 --> 00:00:20,783
THE WINNER SEALS OUR FATE.

8
00:00:20,784 --> 00:00:23,587
THE TUG OF WAR IS GRAVITY,

9
00:00:23,588 --> 00:00:25,256
WHICH IS TRYING
TO SHRINK IT DOWN,

10
00:00:25,257 --> 00:00:28,058
AND THE EXPANSION OF SPACE
AND TIME ITSELF.

11
00:00:28,059 --> 00:00:30,393
WILL GRAVITY TRIUMPH?

12
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THE UNIVERSE WILL GET SMALLER
AND SMALLER, HOTTER AND HOTTER.

13
00:00:33,564 --> 00:00:36,566
OR WILL EXPANSION
GET THE UPPER HAND?

14
00:00:36,567 --> 00:00:40,538
EVEN THE ELECTRONS AROUND
YOUR ATOMS WILL BE RIPPED APART.

15
00:00:40,539 --> 00:00:42,005
THE END IS COMING,

16
00:00:42,006 --> 00:00:45,543
AND IT COULD BE
SOONER THAN YOU THINK.

17
00:00:49,847 --> 00:00:52,849
-- Captions by VITAC --
 www.vitac.com

18
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CAPTIONS PAID FOR BY
DISCOVERY COMMUNICATIONS

19
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THE UNIVERSE IS EVERYTHING

20
00:01:01,995 --> 00:01:05,698
ALL SPACE, ALL TIME, ALL MATTER.

21
00:01:07,967 --> 00:01:10,936
THE EARTH IS A SPECK
BY COMPARISON,

22
00:01:10,937 --> 00:01:15,507
A GRAIN OF ROCK ORBITING JUST
ONE OF THE 200 BILLION STARS

23
00:01:15,508 --> 00:01:18,579
IN OUR HOME GALAXY,
THE MILKY WAY.

24
00:01:21,881 --> 00:01:25,684
IN TURN, THIS ENORMOUS STRUCTURE
IS JUST A DROP

25
00:01:25,685 --> 00:01:28,287
IN AN OCEAN OF GALAXIES
THAT STRETCH

26
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FOR 90 BILLION LIGHT YEARS.

27
00:01:32,925 --> 00:01:35,026
AND ALL OF THIS,

28
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FROM THE BIGGEST GALAXY
TO THE SMALLEST ATOM,

29
00:01:39,199 --> 00:01:41,402
WILL ONE DAY DIE.

30
00:01:43,237 --> 00:01:45,638
WE DON'T SEE EVIDENCE
OF ANYTHING BEING ETERNAL.

31
00:01:45,639 --> 00:01:47,338
ETERNITY DOESN'T EXIST.

32
00:01:47,339 --> 00:01:49,609
EVEN SPACE AND TIME
WILL COME TO AN END.

33
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THE UNIVERSE HAS BEEN
EXPANDING SINCE ITS BIRTH,

34
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GRADUALLY BURNING THROUGH
THE FUEL THAT LIGHTS ITS STARS.

35
00:01:59,052 --> 00:02:02,054
BUT WHAT HAPPENS
WHEN THE FUEL RUNS OUT?

36
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WILL IT ALL JUST FADE AWAY?

37
00:02:04,557 --> 00:02:06,960
STARS DIE OUT,
USE UP THEIR NUCLEAR FUEL.

38
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WE HAVE AN EMPTY, COLD,
DESOLATE UNIVERSE.

39
00:02:09,564 --> 00:02:11,632
JUST DEAD REMNANTS OF STARS --

40
00:02:11,633 --> 00:02:13,734
BLACK HOLES, NEUTRON STARS.

41
00:02:13,735 --> 00:02:15,268
EVENTUALLY, THEY DECAY AWAY,

42
00:02:15,269 --> 00:02:18,204
AND YOU'RE LEFT WITH A THIN HAZE
OF VERY LOW ENERGY LIGHT.

43
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THAT'S IT.

44
00:02:19,540 --> 00:02:21,306
WE USED TO THINK THE UNIVERSE

45
00:02:21,307 --> 00:02:24,077
WOULD CRUISE GENTLY
INTO OLD AGE.

46
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BUT OVER THE PAST FEW DECADES,

47
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ASTRONOMERS HAVE
REVEALED A VERY DIFFERENT

48
00:02:29,650 --> 00:02:31,418
AND DISTURBING PICTURE.

49
00:02:31,419 --> 00:02:34,353
THE UNIVERSE ISN'T CRUISING.

50
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IT'S FIGHTING FOR ITS LIFE.

51
00:02:36,189 --> 00:02:38,458
IT MAY SEEM PEACEFUL HERE
ON EARTH ON A NICE, SUNNY DAY,

52
00:02:38,459 --> 00:02:40,293
BUT IN FACT, ABOVE US
AND ALL AROUND US,

53
00:02:40,294 --> 00:02:43,429
THROUGHOUT THE UNIVERSE,
A BATTLE IS RAGING,

54
00:02:43,430 --> 00:02:45,467
AND IT HAS RAGED
SINCE THE BEGINNING OF TIME.

55
00:02:46,335 --> 00:02:49,904
TWO DEADLY FORCES
GRAPPLE FOR CONTROL.

56
00:02:49,905 --> 00:02:54,441
THE FIRST, EXPANSION,
PULLS GALAXIES APART,

57
00:02:54,442 --> 00:02:57,477
COOLING THE UNIVERSE
AND THREATENING IT

58
00:02:57,478 --> 00:03:00,548
WITH A FROZEN EXTINCTION.

59
00:03:00,549 --> 00:03:05,085
THE SECOND, GRAVITY, TRIES TO
CRUSH EVERYTHING BACK TOGETHER,

60
00:03:05,086 --> 00:03:08,924
ANNIHILATING THE UNIVERSE
IN A DENSE BALL OF FIRE.

61
00:03:11,492 --> 00:03:15,096
WILL GRAVITY OR EXPANSION WIN?

62
00:03:15,097 --> 00:03:17,131
OR WILL IT END IN A TIE?

63
00:03:17,132 --> 00:03:20,937
THESE TWO COLOSSAL FORCES
YIELD THREE ENDGAMES.

64
00:03:21,537 --> 00:03:23,604
ONE IS THE BIG FREEZE.

65
00:03:23,605 --> 00:03:26,573
EXPANSION WINS, AND THE UNIVERSE
JUST EXPANDS FOREVER.

66
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THE SECOND IS THAT THERE IS
A DELICATE BALANCE

67
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BETWEEN THE EXPANSION

68
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AND THE AMOUNT OF GRAVITATIONAL
ATTRACTION,

69
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AND THE UNIVERSE GETS
TO A PARTICULAR SIZE,

70
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AND IT PRETTY MUCH STAYS THERE.

71
00:03:35,685 --> 00:03:37,353
AND THE THIRD OUTCOME IS THAT

72
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THE GRAVITATIONAL
ATTRACTION WINS,

73
00:03:39,189 --> 00:03:40,822
AND THE EXPANSION STOPS,

74
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AND THE UNIVERSE
BEGINS TO GET SMALLER

75
00:03:42,558 --> 00:03:45,728
UNTIL, EVENTUALLY,
IT GOES BACK TO A BIG CRUNCH.

76
00:03:47,931 --> 00:03:50,265
SO FAR,
THE UNIVERSE SEEMS BALANCED

77
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ON A TIGHTROPE BETWEEN
EXPANSION AND CONTRACTION.

78
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BUT WILL IT KEEP ITS EQUILIBRIUM
UNTIL IT RUNS OUT OF STEAM,

79
00:03:57,608 --> 00:04:00,411
OR WILL SOMETHING
TIP THE BALANCE?

80
00:04:02,446 --> 00:04:05,382
I DON'T THINK THERE'S
ANY BIGGER QUESTION THAN,

81
00:04:05,383 --> 00:04:07,616
WHERE IS THE UNIVERSE GOING?

82
00:04:07,617 --> 00:04:11,154
TO PREDICT THE FUTURE,
COSMOLOGISTS HAVE ALWAYS LOOKED

83
00:04:11,155 --> 00:04:15,358
TO THE PAST, BACK TO
THE BEGINNING OF EXPANSION,

84
00:04:15,359 --> 00:04:20,131
THE BEGINNING OF GRAVITY,
THE BEGINNING OF EVERYTHING.

85
00:04:22,732 --> 00:04:27,702
13.8 BILLION YEARS AGO,
AN INFINITELY DENSE,

86
00:04:27,703 --> 00:04:32,408
HOT SPECK IGNITES
AND SUDDENLY EXPANDS OUTWARD --

87
00:04:32,409 --> 00:04:34,412
THE BIG BANG.

88
00:04:35,946 --> 00:04:39,516
ALL ENERGY, ALL SPACE,
AND ALL MATTER...

89
00:04:41,251 --> 00:04:44,286
...THE BUILDING BLOCKS OF
THE UNIVERSE WE SEE TODAY,

90
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ARE CREATED AND SET IN MOTION.

91
00:04:47,759 --> 00:04:49,994
THINK OF IT.

92
00:04:49,995 --> 00:04:52,297
EVERYTHING YOU SEE AROUND US

93
00:04:52,298 --> 00:04:56,934
CONCENTRATED INTO A PRIMORDIAL
FIREBALL THAT EXPLODED,

94
00:04:56,935 --> 00:04:59,738
SENDING ALL THE GALAXIES
INTO MOTION.

95
00:05:03,809 --> 00:05:07,477
THAT OUTWARD BLAST,
THE BIRTH OF EXPANSION,

96
00:05:07,478 --> 00:05:10,147
IS STILL GOING ON TODAY.

97
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WITHOUT IT, WE WOULDN'T HAVE
A UNIVERSE BIG ENOUGH

98
00:05:13,552 --> 00:05:16,354
FOR STARS
AND GALAXIES TO EXIST IN.

99
00:05:16,355 --> 00:05:19,623
EXPANSION IS AN ASTONISHING
FORCE OF NATURE.

100
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IT WORKS BY INFLATING
THE FABRIC OF SPACE-TIME.

101
00:05:23,928 --> 00:05:27,599
SPACE BETWEEN GALAXIES EXPANDS,

102
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AND IT PUSHES
THE GALAXIES APART.

103
00:05:29,903 --> 00:05:35,006
SPACE CARRIES OBJECTS WITH IT
LIKE A SURFER ON A WAVE.

104
00:05:35,007 --> 00:05:37,409
IT'S GOING ON
IN EVERY PART OF SPACE.

105
00:05:37,410 --> 00:05:39,078
EVEN INSIDE YOUR BODY RIGHT NOW,

106
00:05:39,079 --> 00:05:41,013
THERE'S A PRESSURE
FOR SPACE TO EXPAND.

107
00:05:41,880 --> 00:05:44,917
EXPANSION GENERATED
THE VAST, MOVING STAGE

108
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ON WHICH TODAY'S UNIVERSE
PLAYS OUT.

109
00:05:47,553 --> 00:05:50,456
BUT LEFT UNCHECKED,
IT COULD HAVE BEEN A FORCE

110
00:05:50,457 --> 00:05:52,590
FOR UTTER ANNIHILATION.

111
00:05:52,591 --> 00:05:54,826
IF THE UNIVERSE HAD
BEEN EXPANDING MUCH FASTER,

112
00:05:54,827 --> 00:05:56,595
IT WOULD HAVE EMPTIED OUT
SO FAST,

113
00:05:56,596 --> 00:05:58,864
YOU WOULDN'T HAVE HAD TIME
TO MAKE GALAXIES,

114
00:05:58,865 --> 00:06:00,000
PLANETS, PEOPLE.

115
00:06:02,668 --> 00:06:04,270
THE FACT
THAT WE'RE HERE

116
00:06:04,271 --> 00:06:06,840
MEANS THAT SOMETHING MUST HAVE
PUT ON THE BRAKES.

117
00:06:06,841 --> 00:06:11,443
IT WAS, OF COURSE,
OUR UNIVERSAL GLUE -- GRAVITY.

118
00:06:11,444 --> 00:06:14,913
GRAVITY AND MATTER
GO HAND IN HAND.

119
00:06:14,914 --> 00:06:17,816
THE MORE MASSIVE THE OBJECT,

120
00:06:17,817 --> 00:06:20,919
THE MORE PULL IT EXERTS
ON EVERYTHING AROUND IT.

121
00:06:20,920 --> 00:06:26,526
IT DRAWS ATOM TO ATOM,
PARTICLE TO PARTICLE...

122
00:06:27,228 --> 00:06:32,532
...BUILDING STARS, NEBULAS,

123
00:06:32,533 --> 00:06:34,868
GALAXIES --

124
00:06:34,869 --> 00:06:39,006
THE HARDWARE OF THE UNIVERSE
WE SEE TODAY.

125
00:06:39,007 --> 00:06:41,840
BUT GRAVITY
IS A DOUBLE-EDGED SWORD.

126
00:06:41,841 --> 00:06:44,744
TOO MUCH, AND THE EARLY UNIVERSE
WOULD NEVER HAVE GOTTEN

127
00:06:44,745 --> 00:06:46,912
OUT OF THE STARTING BLOCKS.

128
00:06:46,913 --> 00:06:48,948
IF IT HAD BEEN
EXPANDING MORE SLOWLY,

129
00:06:48,949 --> 00:06:51,217
IT WOULD HAVE RE-COLLAPSED
INTO ANOTHER SINGULARITY.

130
00:06:51,218 --> 00:06:53,986
AND AGAIN, YOU WOULDN'T HAVE HAD
THE TIME TO MAKE GALAXIES,

131
00:06:53,987 --> 00:06:55,789
PLANETS, OR PEOPLE.

132
00:06:55,790 --> 00:06:57,424
SO WE LIVE IN THE GOLDILOCKS
UNIVERSE.

133
00:06:57,425 --> 00:06:59,559
WE LIVE IN THE UNIVERSE
THAT LASTS LONG ENOUGH

134
00:06:59,560 --> 00:07:02,061
THAT WE CAN BE HERE,
BUT EXPANDS GENTLY ENOUGH

135
00:07:02,062 --> 00:07:03,997
THAT WE HAVE TIME TO FORM.

136
00:07:06,767 --> 00:07:10,569
THE UNIVERSE HAS
LASTED FOR 13.8 BILLION YEARS,

137
00:07:10,570 --> 00:07:14,542
THANKS TO THE OPPOSING FORCES
OF GRAVITY AND EXPANSION.

138
00:07:14,543 --> 00:07:18,612
BUT JUST HOW STABLE
IS THIS BALANCING ACT?

139
00:07:18,613 --> 00:07:22,115
DOES OUR UNIVERSE HAVE JUST
THE RIGHT AMOUNT OF STUFF IN IT

140
00:07:22,116 --> 00:07:24,216
TO KEEP IT FROM
RUNAWAY EXPANSION

141
00:07:24,217 --> 00:07:26,287
OR CATASTROPHIC COLLAPSE?

142
00:07:26,888 --> 00:07:29,757
IN THE 1920s,
SCIENTISTS DID THE MATH,

143
00:07:29,758 --> 00:07:33,594
AND THE RESULTS WERE
ANYTHING BUT REASSURING.

144
00:07:33,595 --> 00:07:36,831
THE MORE MATTER YOU HAVE,
THE MORE GRAVITY YOU HAVE.

145
00:07:36,832 --> 00:07:40,168
IF YOU HAVE LOTS OF MATTER
IN A VERY DENSE UNIVERSE,

146
00:07:40,169 --> 00:07:43,238
PERHAPS THE UNIVERSE
BEGINS TO RE-COLLAPSE.

147
00:07:43,239 --> 00:07:45,339
OR, IF YOU HAVE
VERY LITTLE MATTER,

148
00:07:45,340 --> 00:07:47,709
THE UNIVERSE WOULD
FREEZE TO DEATH.

149
00:07:47,710 --> 00:07:51,879
SO WHAT IS THE CRITICAL DENSITY,
THE BORDER BETWEEN THE TWO?

150
00:07:51,880 --> 00:07:56,416
IT'S APPROXIMATELY FIVE HYDROGEN
ATOMS PER CUBIC METER.

151
00:07:56,417 --> 00:08:01,822
SO THINK OF A CUBIC YARD,
AND PUT JUST FIVE HYDROGEN ATOMS

152
00:08:01,823 --> 00:08:04,659
INSIDE,
AND THAT IS THE TIPPING POINT.

153
00:08:04,660 --> 00:08:06,793
IF YOU PUT MORE THAN FIVE ATOMS,

154
00:08:06,794 --> 00:08:08,796
THEN THE UNIVERSE WILL
BEGIN TO COLLAPSE.

155
00:08:08,797 --> 00:08:10,331
IF YOU HAVE
LESS THAN FIVE ATOMS,

156
00:08:10,332 --> 00:08:11,934
THEN THE UNIVERSE
JUST KEEPS ON GOING.

157
00:08:12,935 --> 00:08:15,135
IF WE THOUGHT
THE UNIVERSE WAS BALANCED

158
00:08:15,136 --> 00:08:18,306
ON A TIGHTROPE BEFORE,
THE CRITICAL DENSITY QUESTION

159
00:08:18,307 --> 00:08:22,579
SHOWED US THAT THE ROPE
WAS MORE LIKE A RAZOR BLADE.

160
00:08:22,946 --> 00:08:25,882
YET, WHEN ASTRONOMERS TOOK
ADDITIONAL MEASUREMENTS,

161
00:08:25,883 --> 00:08:28,316
THEY LIKED WHAT THEY SAW.

162
00:08:28,317 --> 00:08:31,720
THE UNIVERSE APPEARED TO CONTAIN
JUST THE RIGHT AMOUNT

163
00:08:31,721 --> 00:08:34,658
OF MATTER TO STAY
AT THE CRITICAL DENSITY.

164
00:08:35,793 --> 00:08:37,893
MORE AND MORE,
THE INDIRECT EVIDENCE

165
00:08:37,894 --> 00:08:40,729
AND THE THEORETICAL
ARGUMENTS SUGGESTED

166
00:08:40,730 --> 00:08:43,432
THAT THE UNIVERSE MUST BE
EXACTLY AT THE BOUNDARY

167
00:08:43,433 --> 00:08:45,268
BETWEEN A UNIVERSE
THAT WOULD COLLAPSE

168
00:08:45,269 --> 00:08:47,570
AND ONE THAT
WOULD EXPAND FOREVER,

169
00:08:47,571 --> 00:08:51,206
THAT WE WERE TEETERING
ON THE HAIRY EDGE OF EXPANSION.

170
00:08:51,207 --> 00:08:55,478
THE UNIVERSE SEEMED
SO PERFECTLY BALANCED

171
00:08:55,479 --> 00:08:59,380
THAT IT WOULD HEAD QUIETLY
INTO OLD AGE.

172
00:08:59,381 --> 00:09:02,918
THEN, IN THE 1970s, ASTRONOMERS
MADE AN OBSERVATION

173
00:09:02,919 --> 00:09:04,921
THAT SHOCKED THEM.

174
00:09:04,922 --> 00:09:08,825
THE COSMOS WAS FILLED
WITH INVISIBLE STUFF,

175
00:09:08,826 --> 00:09:13,531
AND ITS GRAVITY COULD CAUSE
A CATASTROPHIC COLLAPSE.

176
00:09:23,943 --> 00:09:27,078
THE UNIVERSE
IS BALANCED ON A TIGHTROPE.

177
00:09:27,079 --> 00:09:31,215
ON EACH SIDE OF THE DROP
LIES AN EARLY DEATH --

178
00:09:31,216 --> 00:09:34,954
A BIG FREEZE, FUELED BY
THE RUNAWAY STRETCHING OF SPACE,

179
00:09:34,955 --> 00:09:40,858
OR A BIG CRUNCH, THE RESULT OF
GRAVITY OVERCOMING EXPANSION.

180
00:09:40,859 --> 00:09:44,328
40 YEARS AGO, SCIENTISTS
BELIEVED WE'D STAY BALANCED

181
00:09:44,329 --> 00:09:47,899
BETWEEN THESE FATES
FOR ETERNITY.

182
00:09:47,900 --> 00:09:50,135
NOW THINGS HAVE CHANGED
TREMENDOUSLY,

183
00:09:50,136 --> 00:09:52,871
BECAUSE WE'VE DISCOVERED
SOMETHING WE NEVER KNEW ABOUT

184
00:09:52,872 --> 00:09:53,672
40 YEARS AGO.

185
00:09:54,273 --> 00:09:58,944
IN THE 1970s,
ASTRONOMERS ARE STUNNED.

186
00:09:58,945 --> 00:10:02,647
SOME UNKNOWN FORM OF MATTER,
INVISIBLE TO TELESCOPES,

187
00:10:02,648 --> 00:10:05,349
DWARFS WHAT WE THOUGHT WAS
OUT THERE,

188
00:10:05,350 --> 00:10:09,121
NOT A FRACTION MORE,
BUT FIVE TIMES MORE.

189
00:10:09,122 --> 00:10:12,290
WE USED TO THINK
THAT GRAVITY CAME FROM STARS

190
00:10:12,291 --> 00:10:15,294
AND OBJECTS YOU CAN SEE --
END OF STORY.

191
00:10:15,295 --> 00:10:18,665
NOW, WE REALIZE THAT THAT NAIVE
PICTURE IS ACTUALLY WRONG.

192
00:10:19,700 --> 00:10:22,001
ASTRONOMERS MAKE
THE DISCOVERY,

193
00:10:22,002 --> 00:10:25,373
STUDYING THE CLOCKWORK
NATURE OF OUR UNIVERSE.

194
00:10:26,775 --> 00:10:29,442
THE HUGE GRAVITY OF THE SUN
HOLDS THE EARTH

195
00:10:29,443 --> 00:10:33,582
AND ALL THE OTHER PLANETS
IN A DELICATE CIRCULAR DANCE.

196
00:10:37,451 --> 00:10:40,987
THE SUN'S MASS CONTROLS
THE SPEED OF THESE ORBITS.

197
00:10:40,988 --> 00:10:44,157
IF IT WERE MORE MASSIVE,
THE PLANETS WOULD ORBIT

198
00:10:44,158 --> 00:10:45,825
MUCH MORE QUICKLY.

199
00:10:45,826 --> 00:10:48,395
AND IF IT WERE SMALLER,
IT WOULD TAKE MUCH LONGER

200
00:10:48,396 --> 00:10:51,032
FOR A PLANET TO COMPLETE
AN ORBIT.

201
00:10:53,233 --> 00:10:56,502
GALAXIES RUN
LIKE CLOCKWORK, TOO.

202
00:10:56,503 --> 00:10:59,772
THE VAST MASS AT THE CENTER
PULLS THE OUTER STARS

203
00:10:59,773 --> 00:11:03,176
INTO CIRCULAR,
PLANET-LIKE ORBITS.

204
00:11:03,177 --> 00:11:05,679
ASTRONOMERS MAKE
PRECISE MEASUREMENTS

205
00:11:05,680 --> 00:11:09,348
OF THESE GALACTIC
ORBITS IN THE 1970s.

206
00:11:09,349 --> 00:11:12,521
THE RESULTS CHANGE EVERYTHING.

207
00:11:13,422 --> 00:11:15,989
THE GALAXIES
WERE SPINNING TOO FAST.

208
00:11:15,990 --> 00:11:17,525
WAY TOO FAST.

209
00:11:20,596 --> 00:11:23,465
EVEN ACCOUNTING FOR
THE SUPERMASSIVE BLACK HOLES

210
00:11:23,466 --> 00:11:27,768
AT THEIR CENTER, NINE-TENTHS
OF THEIR MASS WAS MISSING.

211
00:11:27,769 --> 00:11:30,605
BY RIGHTS,
THE GALAXY SHOULD FLY APART.

212
00:11:30,606 --> 00:11:32,774
BY RIGHTS, THE EARTH
SHOULD HAVE BEEN FLUNG

213
00:11:32,775 --> 00:11:35,744
INTO INTERGALACTIC SPACE
BILLIONS OF YEARS AGO.

214
00:11:35,745 --> 00:11:38,946
WE SHOULD HAVE NO
MILKY WAY GALAXY, AND YET,

215
00:11:38,947 --> 00:11:40,683
OUR UNIVERSE IS
FULL OF GALAXIES.

216
00:11:44,753 --> 00:11:47,688
AN IMMENSE
ADDITIONAL SOURCE OF GRAVITY

217
00:11:47,689 --> 00:11:50,591
MUST BE HOLDING GALAXIES
TOGETHER.

218
00:11:50,592 --> 00:11:53,827
BUT NO MATTER WHERE ASTRONOMERS
POINT THEIR TELESCOPES,

219
00:11:53,828 --> 00:11:55,764
THEY SEE NOTHING.

220
00:11:55,765 --> 00:11:59,299
NOT A GLIMMER, NOT A SHADOW.

221
00:11:59,300 --> 00:12:04,172
WHATEVER THIS NEW STUFF IS,
IT DOESN'T EMIT LIGHT,

222
00:12:04,173 --> 00:12:07,808
REFLECT LIGHT,
OR EVEN BLOCK LIGHT.

223
00:12:07,809 --> 00:12:10,713
THEY CALL IT DARK MATTER.

224
00:12:10,746 --> 00:12:14,084
WHAT WE'VE LEARNED IS THAT MOST
OF THE MATTER IN THE UNIVERSE

225
00:12:14,085 --> 00:12:16,720
IS NOT ORDINARY STUFF.
IT'S NOT ATOMS.

226
00:12:16,721 --> 00:12:19,522
IT'S NOT PARTICLES WE'VE YET
DETECTED IN ANY EXPERIMENT

227
00:12:19,523 --> 00:12:21,224
DONE HERE ON EARTH.

228
00:12:21,225 --> 00:12:23,860
IT'S SOME NEW KIND OF PARTICLE
THAT WE CALL THE DARK MATTER.

229
00:12:26,996 --> 00:12:28,898
DARK MATTER FILLS THE UNIVERSE,

230
00:12:28,899 --> 00:12:32,002
OUTSTRIPPING NORMAL MATTER
BY 5-TO-1.

231
00:12:35,605 --> 00:12:40,109
VAST FILAMENTS SPREAD OUT
THROUGHOUT THE COSMOS,

232
00:12:40,110 --> 00:12:44,581
AND BRIGHT GALAXIES CLUSTER
WHERE DARK MATTER IS THICKEST.

233
00:12:46,917 --> 00:12:51,253
DARK MATTER PROVIDES
THE SCAFFOLDING THAT UNDERLIES

234
00:12:51,254 --> 00:12:54,123
HOW THE MATTER IN THE UNIVERSE
STRUCTURES ITSELF,

235
00:12:54,124 --> 00:12:56,027
WHERE IT GOES,
AND WHAT IT DOES.

236
00:12:56,894 --> 00:12:58,829
SO,
DARK MATTER DICTATED

237
00:12:58,830 --> 00:13:02,396
HOW THE UNIVERSE UNFOLDED.

238
00:13:02,397 --> 00:13:04,535
IT SEEMS AS IF
OUT OF THE HOT BIG BANG,

239
00:13:04,536 --> 00:13:08,171
DARK MATTER CONDENSED FIRST,
BEFORE ATOMS,

240
00:13:08,172 --> 00:13:11,141
AND DARK MATTER BEGAN
TO BECOME CLUMPY.

241
00:13:11,142 --> 00:13:14,344
THE CLUMPINESS THEN BEGAN
TO ATTRACT ATOMS

242
00:13:14,345 --> 00:13:18,047
AS THEY WERE FORMED LATER,
AND THAT FORMED GALAXIES.

243
00:13:18,048 --> 00:13:20,084
AND IN SOME SENSE,
THE DARK MATTER THEREFORE

244
00:13:20,085 --> 00:13:23,689
PROVIDES KIND OF A WOMB THAT
ALLOWS THE BIRTH OF OUR GALAXY.

245
00:13:26,925 --> 00:13:30,094
DARK MATTER HOLDS
THE UNIVERSE TOGETHER,

246
00:13:30,095 --> 00:13:32,564
BUT IT ALSO THREATENS
TO DESTROY IT.

247
00:13:35,397 --> 00:13:36,098
ONE OF THE MOST
AMAZING DISCOVERIES

248
00:13:36,099 --> 00:13:38,536
OF THE PAST FEW DECADES
IS DARK MATTER,

249
00:13:38,537 --> 00:13:40,502
THE FACT THAT THERE'S MUCH MORE
MATTER IN THE UNIVERSE

250
00:13:40,503 --> 00:13:41,972
THAN WE WERE AWARE OF.

251
00:13:41,973 --> 00:13:44,476
AND ALL OF THAT MATTER
HAS A LOT OF GRAVITY.

252
00:13:44,477 --> 00:13:46,609
SO ALL THIS NEW MATTER,
ALL THIS NEW GRAVITY

253
00:13:46,610 --> 00:13:49,013
MUST BE SLOWING DOWN
THE EXPANSION OF THE UNIVERSE.

254
00:13:49,781 --> 00:13:52,717
DARK MATTER MAY EVEN
TIP THE COSMIC SCALES

255
00:13:52,718 --> 00:13:54,718
IN FAVOR OF GRAVITY,

256
00:13:54,719 --> 00:13:58,488
DEFEATING EXPANSION
AND PULLING THE ENTIRE UNIVERSE

257
00:13:58,489 --> 00:14:01,093
TOWARDS A DEATH BY FIRE.

258
00:14:01,094 --> 00:14:03,895
IT'S CALLED THE BIG CRUNCH,

259
00:14:03,896 --> 00:14:06,265
AND THIS IS HOW
IT WOULD PLAY OUT.

260
00:14:07,967 --> 00:14:12,303
FOR A FRACTION OF A SECOND,
THE UNIVERSE STALLS,

261
00:14:12,304 --> 00:14:16,040
POISED BETWEEN
EXPANSION AND CONTRACTION.

262
00:14:16,041 --> 00:14:20,144
THEN, GRAVITY KICKS OFF
A CATACLYSM.

263
00:14:20,145 --> 00:14:22,613
WHEN YOU LOOKED OUT,
THE VERY FIRST THINGS

264
00:14:22,614 --> 00:14:24,549
AS IT BEGAN TO TURN AROUND
THAT YOU BEGAN TO SEE

265
00:14:24,550 --> 00:14:27,184
IS THAT GALAXIES, INSTEAD OF
MOVING AWAY FROM US ON AVERAGE,

266
00:14:27,185 --> 00:14:29,689
WOULD BEGIN TO BE MOVING TOWARDS
US ON AVERAGE.

267
00:14:30,823 --> 00:14:33,794
THE WHOLE UNIVERSE WOULD LOOK
LIKE IT WAS COMING TO GET US.

268
00:14:35,596 --> 00:14:38,197
AS SPACE
CONTRACTS FURTHER,

269
00:14:38,198 --> 00:14:42,033
THE DENSITY OF MATTER INCREASES,
GRAVITY GETS STRONGER,

270
00:14:42,034 --> 00:14:47,206
TEMPERATURES SOAR
AS THE CRUNCH GATHERS MOMENTUM.

271
00:14:47,207 --> 00:14:49,542
GALAXIES BEGIN TO COLLIDE,

272
00:14:49,543 --> 00:14:52,512
GAS CLOUDS BEGIN TO COLLIDE,

273
00:14:52,513 --> 00:14:55,616
PLANETS SLAM INTO THE EARTH.

274
00:14:59,385 --> 00:15:02,955
BLACK HOLES WILL EXECUTE A DEATH
DANCE AROUND EACH OTHER.

275
00:15:02,956 --> 00:15:06,392
TEMPERATURES, OF COURSE,
WILL CONTINUE TO SKYROCKET.

276
00:15:06,393 --> 00:15:10,230
MATTER, SPACE,
AND TIME IMPLODE

277
00:15:10,231 --> 00:15:13,164
UNTIL EVERYTHING IN THE UNIVERSE
IS COMPRESSED

278
00:15:13,165 --> 00:15:19,004
INTO A TINY SPECK OF INFINITE
MASS, HEAT, AND PRESSURE.

279
00:15:19,005 --> 00:15:21,773
FOR THE LAST STAGES
OF THE BIG CRUNCH,

280
00:15:21,774 --> 00:15:24,976
GALAXIES WILL COLLIDE
AND FORM A PRIMORDIAL ATOM.

281
00:15:24,977 --> 00:15:29,349
AND THEN, LIFE AS WE KNOW IT
WILL BE IMPOSSIBLE.

282
00:15:29,350 --> 00:15:31,783
WE'RE BACK
TO WHERE IT ALL BEGAN,

283
00:15:31,784 --> 00:15:32,921
BACK AT THE BIG BANG.

284
00:15:33,722 --> 00:15:37,459
THE UNIVERSE THAT WE LIVE IN
WILL CEASE TO EXIST.

285
00:15:41,028 --> 00:15:46,766
BUT SOME BELIEVE A BIG CRUNCH
COULD HERALD A NEW BEGINNING.

286
00:15:46,767 --> 00:15:49,102
WE DON'T KNOW WHAT THE END POINT
OF A BIG CRUNCH WOULD BE,

287
00:15:49,103 --> 00:15:51,838
BECAUSE THE LAWS OF PHYSICS
BREAK DOWN.

288
00:15:51,839 --> 00:15:55,309
IT'S POSSIBLE, AND INDEED,
PHILOSOPHICALLY VERY PLEASANT,

289
00:15:55,310 --> 00:15:59,545
TO IMAGINE THAT THAT CRUNCH
WOULD SOMEHOW END UP EVOLVING

290
00:15:59,546 --> 00:16:02,848
INTO AN EXPANSION AGAIN, AND YOU
COULD HAVE A CYCLIC UNIVERSE

291
00:16:02,849 --> 00:16:04,383
WHICH GOES ON FOREVER.

292
00:16:04,384 --> 00:16:08,123
PERHAPS AT THAT POINT, WE WILL
RECREATE ANOTHER BIG BANG.

293
00:16:12,060 --> 00:16:14,428
IT'S CONCEIVABLE THAT AS
EVERYTHING COMES TOGETHER

294
00:16:14,429 --> 00:16:17,963
IN THE CRUNCH, SOMETHING SORT OF
KEEPS IT FROM JUST CONTINUING

295
00:16:17,964 --> 00:16:21,635
AND PUSHES OUT IN A HOT,
DENSE, SMOOTH STATE,

296
00:16:21,636 --> 00:16:24,338
AND FROM THE OTHER SIDE,
IT LOOKS LIKE A BIG BANG,

297
00:16:24,339 --> 00:16:26,073
AND A NEW UNIVERSE HAS BEEN
CREATED.

298
00:16:26,074 --> 00:16:28,942
OUR BIG BANG MIGHT HAVE BEEN
SOMEONE ELSE'S BIG CRUNCH.

299
00:16:28,943 --> 00:16:31,245
BUT JUST WHEN
SCIENTISTS CAME TO TERMS

300
00:16:31,246 --> 00:16:34,716
WITH DARK MATTER'S BIG CRUNCH,
THE UNIVERSE THREW THEM

301
00:16:34,717 --> 00:16:37,118
ANOTHER, EVEN BIGGER CURVE.

302
00:16:37,119 --> 00:16:41,656
SOME GHOSTLY FORCE SEEMED TO BE
SENDING US HURTLING TOWARD

303
00:16:41,657 --> 00:16:43,757
A COMPLETELY DIFFERENT DEATH.

304
00:16:43,758 --> 00:16:46,561
MY POSTDOCTORAL
SCHOLAR SHOWED ME THE RESULTS.

305
00:16:46,562 --> 00:16:47,730
I NEARLY FELL OFF MY CHAIR.

306
00:16:57,874 --> 00:17:00,210
GRAVITY AND EXPANSION
BATTLE FOR CONTROL

307
00:17:00,211 --> 00:17:03,681
OF OUR UNIVERSE
FOR 14 BILLION YEARS...

308
00:17:07,852 --> 00:17:12,287
...EXPANSION
PUSHING IT OUTWARDS,

309
00:17:12,288 --> 00:17:14,893
GRAVITY PULLING IT IN.

310
00:17:16,394 --> 00:17:18,495
WITH DARK MATTER IN ITS CORNER,

311
00:17:18,496 --> 00:17:20,997
GRAVITY SEEMS TO BE
THE INEVITABLE WINNER.

312
00:17:20,998 --> 00:17:25,568
THE EXTRA MASS WILL DRAG
THE UNIVERSE INTO A BIG CRUNCH,

313
00:17:25,569 --> 00:17:27,604
UNTIL A STUNNING DISCOVERY

314
00:17:27,605 --> 00:17:32,110
REVOLUTIONIZES OUR UNDERSTANDING
OF THE UNIVERSE.

315
00:17:34,444 --> 00:17:39,383
AROUND 1990, TWO TEAMS OF
RESEARCHERS DECIDED TO MEASURE

316
00:17:39,384 --> 00:17:41,450
THE EXPANSION HISTORY
OF THE UNIVERSE

317
00:17:41,451 --> 00:17:44,554
TO DETERMINE WHETHER
IT'S BEEN SLOWING DOWN SO MUCH

318
00:17:44,555 --> 00:17:46,791
THAT IT'LL EVENTUALLY HAVE
A BIG CRUNCH,

319
00:17:46,792 --> 00:17:49,325
OR WHETHER IT HASN'T BEEN
SLOWING DOWN MUCH

320
00:17:49,326 --> 00:17:51,295
AND WILL ETERNALLY EXPAND.

321
00:17:51,296 --> 00:17:55,798
ASTRONOMER ALEX FILIPPENKO
WAS ON ONE TEAM.

322
00:17:55,799 --> 00:17:58,401
SAUL PERLMUTTER LED THE OTHER.

323
00:17:58,402 --> 00:18:01,438
WE REALIZED THAT IT WAS POSSIBLE
FOR THE FIRST TIME

324
00:18:01,439 --> 00:18:05,108
TO GO AND ACTUALLY MAKE
A DIRECT MEASUREMENT

325
00:18:05,109 --> 00:18:07,611
OF HOW MUCH THE UNIVERSE HAD
BEEN SLOWING DOWN IN THE PAST.

326
00:18:07,813 --> 00:18:09,347
BOTH TEAMS WANT
TO MEASURE

327
00:18:09,348 --> 00:18:11,648
THE SPEED OF DISTANT GALAXIES.

328
00:18:11,649 --> 00:18:15,520
BUT BECAUSE THE GALAXIES ARE
TOO DIM AND TOO FAR AWAY,

329
00:18:15,521 --> 00:18:17,557
THEY LOOK FOR SOMETHING
BRIGHTER.

330
00:18:22,461 --> 00:18:26,931
BILLIONS OF LIGHT YEARS
FROM EARTH, A STAR DETONATES.

331
00:18:26,932 --> 00:18:29,600
THIS IS A SUPERNOVA,

332
00:18:29,601 --> 00:18:33,605
A DYING STAR'S
BRILLIANT FINAL GASP.

333
00:18:33,606 --> 00:18:37,541
IT BURNS BRIGHTLY, 5 BILLION
TIMES BRIGHTER THAN THE SUN,

334
00:18:37,542 --> 00:18:40,212
BUT BRIEFLY.

335
00:18:40,213 --> 00:18:42,379
PERLMUTTER AND FILIPPENKO
HAVE A WINDOW

336
00:18:42,380 --> 00:18:44,948
OF JUST ONE OR TWO WEEKS
TO MEASURE

337
00:18:44,949 --> 00:18:48,252
HOW MUCH THE GALAXY IT SITS IN
IS SLOWING DOWN

338
00:18:48,253 --> 00:18:50,523
AS IT MOVES AWAY FROM US.

339
00:18:54,628 --> 00:18:57,864
THE TEAMS LOOK FOR SUPERNOVAS
FOR EIGHT YEARS.

340
00:18:57,865 --> 00:19:03,670
THEY MEASURE 42, AND THE RESULTS
SEEM IMPOSSIBLE.

341
00:19:03,671 --> 00:19:06,271
WE PLOTTED THE POINTS
ON THE GRAPHS,

342
00:19:06,272 --> 00:19:09,008
AND...IT DIDN'T MAKE ANY SENSE.

343
00:19:09,009 --> 00:19:10,876
THEY WERE NOT SLOWING DOWN
AT ALL.

344
00:19:10,877 --> 00:19:12,813
THEY WERE ACTUALLY SPEEDING UP.

345
00:19:13,980 --> 00:19:17,584
WHAT BOTH GROUPS FOUND
STUNNED THE WORLD.

346
00:19:17,585 --> 00:19:20,420
IN THE LAST 4 OR 5 BILLION
YEARS,

347
00:19:20,421 --> 00:19:24,589
THE UNIVERSE HAS ACTUALLY BEEN
SPEEDING UP IN ITS EXPANSION.

348
00:19:24,590 --> 00:19:26,425
AN ACCELERATING UNIVERSE,

349
00:19:26,426 --> 00:19:30,396
PROPELLED BY SOMETHING
MYSTERIOUS.

350
00:19:30,397 --> 00:19:32,865
FOR SO LONG, WE'VE BEEN ARGUING
WHETHER THE UNIVERSE WOULD

351
00:19:32,866 --> 00:19:35,701
EXPAND FOREVER OR COLLAPSE
BACK IN ON ITSELF,

352
00:19:35,702 --> 00:19:38,070
BUT NOBODY THOUGHT
THE ANSWER WAS GOING TO BE

353
00:19:38,071 --> 00:19:40,373
THAT THE UNIVERSE WAS
ACCELERATING,

354
00:19:40,374 --> 00:19:42,175
GOING FASTER AND FASTER
ALL THE TIME.

355
00:19:43,745 --> 00:19:47,115
THE ACCELERATION
BEWILDERS THE SCIENTISTS.

356
00:19:47,116 --> 00:19:50,218
IT SEEMS TO DEFY
THE LAWS OF PHYSICS.

357
00:19:50,219 --> 00:19:52,487
IMAGINE I'VE GOT A BASEBALL

358
00:19:52,488 --> 00:19:54,154
AND I THROW IT STRAIGHT UP.

359
00:19:54,155 --> 00:19:56,958
AND INSTEAD OF SLOWING DOWN
ONCE IT LEAVES MY HAND,

360
00:19:56,959 --> 00:19:58,792
WHICH IS WHAT
NORMALLY IT WILL DO,

361
00:19:58,793 --> 00:20:00,661
IT BEGINS TO SLOW DOWN AT FIRST,

362
00:20:00,662 --> 00:20:02,564
BUT THEN IT STARTS
SPEEDING AWAY.

363
00:20:02,565 --> 00:20:04,199
SOMEHOW, IT'S GETTING ENERGY.

364
00:20:04,200 --> 00:20:09,670
THE NEW ENERGY SEEMED
TO BE COMING FROM NOTHING,

365
00:20:09,671 --> 00:20:11,905
THE VACUUM OF SPACE.

366
00:20:11,906 --> 00:20:15,676
THE WORD "VACUUM" TO A SCIENTIST
MEANS COMPLETELY EMPTY SPACE,

367
00:20:15,677 --> 00:20:18,278
NO PARTICLES THERE AT ALL,
NO TEMPERATURE,

368
00:20:18,279 --> 00:20:19,879
NO ENERGY TO SPEAK OF.

369
00:20:19,880 --> 00:20:23,183
BUT THERE'S AN INTRINSIC ENERGY
IN SPACE AND TIME.

370
00:20:23,184 --> 00:20:26,886
EMPTY SPACE HAS ENERGY,
AND THAT ENERGY PRODUCES

371
00:20:26,887 --> 00:20:30,023
A GRAVITATIONAL REPULSION,
A KIND OF ANTI-GRAVITY.

372
00:20:30,024 --> 00:20:34,462
WITHOUT A CLUE WHAT
THIS FORCE IS OR HOW IT WORKS,

373
00:20:34,463 --> 00:20:40,034
ALL SCIENTISTS CAN DO IS GIVE IT
A NAME -- DARK ENERGY.

374
00:20:40,403 --> 00:20:42,804
WE COULD HAVE CALLED IT
WE-DON'T-KNOW ENERGY.

375
00:20:42,805 --> 00:20:44,273
WE COULD HAVE CALLED IT
ANYTHING.

376
00:20:44,274 --> 00:20:46,676
BUT WE DON'T KNOW WHAT IT IS,
AND DARK OR NOT,

377
00:20:46,677 --> 00:20:48,811
IT'S THE BIGGEST MYSTERY
IN PHYSICS.

378
00:20:51,980 --> 00:20:55,016
NASA CALIBRATES
ITS FINEST SPACE TELESCOPES

379
00:20:55,017 --> 00:20:58,152
TO MEASURE HOW MUCH DARK ENERGY
IS OUT THERE,

380
00:20:58,153 --> 00:21:01,489
AND THE RESULT IS MIND-BLOWING.

381
00:21:01,490 --> 00:21:06,295
IT DOMINATES THE MASS OF
THE UNIVERSE BY NEARLY 3-TO-1.

382
00:21:06,296 --> 00:21:07,962
AND THE MORE SPACE EXPANDS,

383
00:21:07,963 --> 00:21:11,132
THE MORE DARK ENERGY
THERE SEEMS TO BE.

384
00:21:11,133 --> 00:21:14,068
DARK ENERGY IS THE ENERGY
OF NOTHING,

385
00:21:14,069 --> 00:21:15,604
AND IT'S REPULSIVE.

386
00:21:15,605 --> 00:21:19,408
THEREFORE, AS THIS DARK ENERGY
REPELS GALAXIES,

387
00:21:19,409 --> 00:21:21,343
THERE'S MORE OF IT,
THERE'S MORE VACUUM.

388
00:21:21,344 --> 00:21:23,446
AND SO THERE'S MORE REPULSION,

389
00:21:23,447 --> 00:21:26,381
AND PERHAPS THAT'S THE REASON
WHY THE UNIVERSE IS ACCELERATING

390
00:21:26,382 --> 00:21:29,718
RIGHT NOW
RATHER THAN SLOWING DOWN.

391
00:21:29,719 --> 00:21:33,189
DARK ENERGY SEEMS TO
KILL THE BIG CRUNCH THEORY,

392
00:21:33,190 --> 00:21:36,257
BUT SCIENTISTS AREN'T YET SURE
HOW DARK ENERGY,

393
00:21:36,258 --> 00:21:39,795
EXPANSION, AND SPACE
ARE CONNECTED.

394
00:21:39,796 --> 00:21:43,131
IF A VOLUME OF SPACE DOUBLES
IN SIZE,

395
00:21:43,132 --> 00:21:46,034
DOES THE DARK ENERGY
INSIDE IT DOUBLE, TOO?

396
00:21:46,035 --> 00:21:48,137
OR DOES IT INCREASE MORE?

397
00:21:48,138 --> 00:21:51,673
A 1-TO-1 RELATIONSHIP LEADS
TO A STEADY EXPANSION.

398
00:21:51,674 --> 00:21:54,810
THE UNIVERSE ENDS
IN A BIG FREEZE.

399
00:21:54,811 --> 00:21:59,381
BUT IF DARK ENERGY INCREASES
ABOVE AND BEYOND EXPANSION,

400
00:21:59,382 --> 00:22:03,955
A NEW, EVEN MORE TERRIFYING END
AWAITS THE UNIVERSE -- A BIG RIP.

401
00:22:04,756 --> 00:22:08,791
IN A BIG RIP SCENARIO,
THE EXPANSION IS SO GREAT

402
00:22:08,792 --> 00:22:12,996
THAT EVEN THE GALAXIES BEGIN
TO EXPAND INTERNALLY,

403
00:22:12,997 --> 00:22:14,331
WHICH MEANS THAT LITERALLY

404
00:22:14,332 --> 00:22:16,268
OUR BODIES
ARE GOING TO BE RIPPED APART.

405
00:22:17,567 --> 00:22:19,068
SCIENTISTS CALCULATE

406
00:22:19,069 --> 00:22:21,405
JUST HOW THE BIG RIP
WILL PLAY OUT.

407
00:22:23,740 --> 00:22:27,810
ONE BY ONE, THE GALAXIES IN
THE NIGHT SKY WILL BLINK OUT

408
00:22:27,811 --> 00:22:30,779
AS SPACE PULLS THEM AWAY
FROM THE EARTH

409
00:22:30,780 --> 00:22:32,582
FASTER THAN THE SPEED OF LIGHT.

410
00:22:34,286 --> 00:22:38,689
60 MILLION YEARS BEFORE THE END,
DARK ENERGY OVERCOMES GRAVITY

411
00:22:38,690 --> 00:22:41,624
ON SMALLER AND SMALLER SCALES.

412
00:22:41,625 --> 00:22:44,928
FIRST GALAXIES START
TO RIP APART,

413
00:22:44,929 --> 00:22:48,798
THEN INSIDES OF GALAXIES
WILL BEGIN TO RIP APART,

414
00:22:48,799 --> 00:22:51,469
AND THEN SOLAR SYSTEMS WILL
BEGIN TO RIP APART...

415
00:22:53,739 --> 00:22:56,708
THEN PLANETS...

416
00:22:56,709 --> 00:23:02,114
AND THEN ROCKS, PEOPLE, ATOMS.

417
00:23:02,115 --> 00:23:05,418
THE END WILL
BE MERCIFULLY QUICK.

418
00:23:06,719 --> 00:23:08,987
IN THE SPACE OF A FEW MINUTES,

419
00:23:08,988 --> 00:23:13,158
ALL THE STARS AND PLANETS IN THE
UNIVERSE WILL BE DESTROYED,

420
00:23:13,159 --> 00:23:17,929
THEIR REMAINS PULLED APART
INTO EVER-SMALLER PIECES

421
00:23:17,930 --> 00:23:20,599
UNTIL FINALLY,
WHEN THE UNIVERSE HAS

422
00:23:20,600 --> 00:23:22,333
LESS THAN A SECOND TO LIVE,

423
00:23:22,334 --> 00:23:25,804
THE SUBATOMIC PARTICLES
THAT MADE ALL MATTER

424
00:23:25,805 --> 00:23:27,471
WILL BE DESTROYED,

425
00:23:27,472 --> 00:23:30,775
AND ALL THAT REMAINS WILL BE
INDIVIDUAL PHOTONS

426
00:23:30,776 --> 00:23:33,077
BECOMING SCARCER AND SCARCER

427
00:23:33,078 --> 00:23:35,814
AS THE SPACE BETWEEN THEM
EXPANDS.

428
00:23:35,815 --> 00:23:38,283
ALL YOU'RE LEFT WITH IS VERY LOW
ENERGY LIGHT

429
00:23:38,284 --> 00:23:39,752
THAT GETS STRETCHED
AND STRETCHED

430
00:23:39,753 --> 00:23:41,854
UNTIL IT MIGHT AS WELL
NOT EXIST AT ALL.

431
00:23:41,855 --> 00:23:43,854
THE LAST THING TO GO --

432
00:23:43,855 --> 00:23:47,359
THE EMPTY VACUUM
OF SPACE ITSELF.

433
00:23:48,896 --> 00:23:51,397
IT'LL BE PULLING ON THE UNIVERSE
SO HARD,

434
00:23:51,398 --> 00:23:54,300
IT COULD TEAR THE FABRIC
OF THE UNIVERSE APART.

435
00:23:54,301 --> 00:23:57,703
REALITY COULD DISSOLVE.

436
00:23:57,704 --> 00:24:01,040
WILL THE UNIVERSE END
WITH A BIG RIP,

437
00:24:01,041 --> 00:24:03,375
OR A BIG FREEZE?

438
00:24:03,376 --> 00:24:07,847
THE ANSWER IS LOCKED INSIDE
THE MYSTERY OF DARK ENERGY.

439
00:24:07,848 --> 00:24:12,619
SOLVE THAT, AND THE FATE
OF THE UNIVERSE BECOMES CLEAR.

440
00:24:24,500 --> 00:24:26,866
THE END
OF THE UNIVERSE IS COMING.

441
00:24:26,867 --> 00:24:29,037
BUT HOW WILL IT PLAY OUT?

442
00:24:29,038 --> 00:24:32,906
FOR A TIME, A BIG CRUNCH
WAS THE LIKELY ANSWER.

443
00:24:32,907 --> 00:24:36,677
DARK MATTER, THE INVISIBLE BULK
OF THE UNIVERSE,

444
00:24:36,678 --> 00:24:39,982
CAUSES SPACE
TO FALL IN ON ITSELF.

445
00:24:41,250 --> 00:24:45,619
GALAXIES COLLIDE.
PLANET MERGES WITH PLANET.

446
00:24:45,620 --> 00:24:50,392
EVERYTHING BECOMES HOTTER
AND HOTTER, DENSER AND DENSER.

447
00:24:50,393 --> 00:24:52,962
THE UNIVERSE IS LIKE
ONE GIANT STAR.

448
00:24:56,732 --> 00:25:00,768
DARK ENERGY KILLS
THE BIG CRUNCH THEORY.

449
00:25:00,769 --> 00:25:03,904
IT ACTS LIKE ROCKET FUEL
FOR THE EXPANSION OF SPACE

450
00:25:03,905 --> 00:25:06,141
BETWEEN GALAXIES.

451
00:25:06,142 --> 00:25:09,379
THEY'RE NOT JUST COASTING.
THEY'RE GETTING PUSHED OUTWARD.

452
00:25:12,713 --> 00:25:14,915
ONLY TWO POSSIBLE FATES
REMAIN --

453
00:25:14,916 --> 00:25:17,618
A BIG RIP OR A BIG FREEZE.

454
00:25:17,619 --> 00:25:20,520
BOTH SCENARIOS RELY
ON DARK ENERGY.

455
00:25:20,521 --> 00:25:23,458
FOR THE UNIVERSE TO BE TORN
TO SHREDS IN A BIG RIP,

456
00:25:23,459 --> 00:25:27,162
DARK ENERGY MUST INCREASE
EXPONENTIALLY IN THE FUTURE.

457
00:25:27,163 --> 00:25:30,498
BUT A BIG FREEZE REQUIRES
A STEADY INCREASE

458
00:25:30,499 --> 00:25:32,000
IN DARK ENERGY,

459
00:25:32,001 --> 00:25:33,902
PUSHING GALAXIES AWAY
FROM EACH OTHER.

460
00:25:34,003 --> 00:25:36,972
WE CAN'T WRITE THE LAST CHAPTER
OF OUR UNIVERSE

461
00:25:36,973 --> 00:25:40,444
UNTIL WE UNDERSTAND THE NATURE
OF DARK ENERGY.

462
00:25:42,045 --> 00:25:44,914
MAY 2009.

463
00:25:44,915 --> 00:25:48,519
THE EUROPEAN SPACE AGENCY
LAUNCHES THE PLANCK SATELLITE

464
00:25:48,520 --> 00:25:52,421
TO SEARCH FOR THE BIRTH
OF DARK ENERGY.

465
00:25:52,422 --> 00:25:56,892
ITS ULTRA-SENSITIVE TELESCOPE
PEERS THROUGH SPACE AND TIME

466
00:25:56,893 --> 00:25:59,428
BACK THROUGH BILLIONS OF YEARS,

467
00:25:59,429 --> 00:26:04,000
TOWARDS THE BEGINNING OF
EVERYTHING, TO CAPTURE THIS.

468
00:26:04,001 --> 00:26:06,503
THIS IS OUR UNIVERSE
AS IT APPEARED

469
00:26:06,504 --> 00:26:09,438
OVER 13 BILLION YEARS AGO,

470
00:26:09,439 --> 00:26:13,477
380,000 YEARS
AFTER THE BIG BANG.

471
00:26:15,045 --> 00:26:17,647
SO WHAT PLANCK HAS DONE
IS TAKE A PICTURE

472
00:26:17,648 --> 00:26:19,916
OF THE EARLY UNIVERSE

473
00:26:19,917 --> 00:26:23,052
AND TOLD US ABOUT WHAT
THE EARLY UNIVERSE IS LIKE

474
00:26:23,053 --> 00:26:25,488
AND GIVEN US OUR MOST DETAILED
AND ACCURATE PICTURE

475
00:26:25,489 --> 00:26:26,822
OF THAT MOMENT IN TIME.

476
00:26:26,823 --> 00:26:29,257
THE UNIVERSE IN THIS PICTURE

477
00:26:29,258 --> 00:26:33,764
IS A HOT SOUP OF PROTONS,
ELECTRONS, AND PHOTONS.

478
00:26:33,765 --> 00:26:36,832
HYDROGEN ATOMS HAVE JUST STARTED
TO FORM,

479
00:26:36,833 --> 00:26:39,569
AND IT'S THE LIGHT FROM THIS
GENESIS OF MATTER

480
00:26:39,570 --> 00:26:41,438
THAT WE SEE HERE.

481
00:26:43,507 --> 00:26:46,744
BLUE AREAS ARE COLDER.
REDS ARE WARM.

482
00:26:46,878 --> 00:26:48,980
EVENTUALLY, THOSE HOT SPOTS,

483
00:26:48,981 --> 00:26:51,182
THOSE RED SPOTS YOU SEE
IN THE MAP,

484
00:26:51,183 --> 00:26:53,818
ARE GOING TO FORM LARGE
SUPERCLUSTERS

485
00:26:53,819 --> 00:26:58,290
MADE UP OF HUNDREDS OR THOUSANDS
OF GALAXIES.

486
00:26:58,291 --> 00:27:02,427
EACH ONE OF THOSE GALAXIES WILL
CONTAIN BILLIONS OF STARS.

487
00:27:04,061 --> 00:27:06,364
GRAVITY
AND EXPANSION ALONE

488
00:27:06,365 --> 00:27:11,068
APPEAR TO DRIVE THE FORMATION
OF THESE EMBRYONIC GALAXIES.

489
00:27:11,069 --> 00:27:15,339
DARK ENERGY DOESN'T SEEM
TO HAVE SWITCHED ON YET.

490
00:27:15,340 --> 00:27:20,178
SO, WHEN DID DARK ENERGY TAKE
CONTROL OF THE UNIVERSE?

491
00:27:26,685 --> 00:27:29,887
ASTRONOMER BRENDA FRYE
IS PART OF A TEAM

492
00:27:29,888 --> 00:27:32,491
USING MASSIVE
GROUND-BASED TELESCOPES

493
00:27:32,492 --> 00:27:35,292
LIKE THIS ONE AT KITT PEAK,
ARIZONA.

494
00:27:35,293 --> 00:27:39,664
SHE PEERS BACK IN TIME
TO CAPTURE THE UNIVERSE

495
00:27:39,665 --> 00:27:42,569
THROUGH ITS CHILDHOOD
AS IT WAS GROWING.

496
00:27:44,604 --> 00:27:47,172
RIGHT.
SO THIS IS AN ALUMINUM PLATE,

497
00:27:47,173 --> 00:27:51,375
AND INTO THIS PLATE ARE
DRILLED 640 INDIVIDUAL HOLES.

498
00:27:51,376 --> 00:27:54,445
EACH ONE IS PUT AT A VERY
SPECIFIC PLACE ON THE MASK

499
00:27:54,446 --> 00:27:58,517
WHICH WILL CORRESPOND TO ONE
PARTICULAR GALAXY IN THE SKY.

500
00:28:00,886 --> 00:28:02,619
DURING EACH OBSERVATION,

501
00:28:02,620 --> 00:28:07,125
THE LIGHT FROM 640 INDIVIDUAL
GALAXIES IS COLLECTED

502
00:28:07,126 --> 00:28:10,529
USING FIBER OPTIC CABLES.

503
00:28:10,530 --> 00:28:13,999
THE SPEED AND RELATIVE POSITION
OF EACH GALAXY IS MEASURED

504
00:28:14,000 --> 00:28:17,871
TO PINPOINT EXACTLY WHERE IT IS
IN SPACE.

505
00:28:17,972 --> 00:28:20,607
SO FAR, THE TEAM
HAS ACCURATELY MAPPED

506
00:28:20,608 --> 00:28:23,443
AROUND A MILLION GALAXIES
IN 3D,

507
00:28:23,444 --> 00:28:25,312
AND THIS IS WHAT THEY LOOK LIKE.

508
00:28:26,546 --> 00:28:29,182
EACH ONE OF THESE FUZZY PATCHES

509
00:28:29,183 --> 00:28:31,016
IS A FULLY GROWN GALAXY

510
00:28:31,017 --> 00:28:35,053
CONTAINING AROUND
200 BILLION STARS.

511
00:28:35,054 --> 00:28:36,723
THIS IS A VERY BASIC
MEASUREMENT,

512
00:28:36,724 --> 00:28:38,890
AND WE THINK THAT
THIS WILL BE ABLE TO HELP US

513
00:28:38,891 --> 00:28:41,895
TO GET A GRASP INTO THE NATURE
OF DARK ENERGY.

514
00:28:41,896 --> 00:28:46,197
SCIENTISTS COMPARE
THIS ADOLESCENT UNIVERSE

515
00:28:46,198 --> 00:28:48,067
TO ITS BABY PICTURES.

516
00:28:48,068 --> 00:28:50,302
IT SHOWS DARK ENERGY EMERGING

517
00:28:50,303 --> 00:28:53,508
WHEN THE UNIVERSE IS 
HALF AS OLD AS IT IS TODAY.

518
00:28:54,776 --> 00:28:57,511
ABOUT 8 BILLION YEARS
AFTER THE BIG BANG,

519
00:28:57,512 --> 00:29:01,748
THIS EXPANSION OF THE UNIVERSE
BEGINS TO ACCELERATE,

520
00:29:01,749 --> 00:29:04,384
AND WE'RE IN THE MIDDLE
OF THIS ACCELERATION.

521
00:29:04,385 --> 00:29:09,089
THE DATA ALSO SHOWS
THAT AS SPACE EXPANDS,

522
00:29:09,090 --> 00:29:13,726
DARK ENERGY
INCREASES IN LOCKSTEP WITH IT.

523
00:29:13,727 --> 00:29:16,062
IF YOU HAD A BOX AND YOU PUT
SOME DARK ENERGY IN IT,

524
00:29:16,063 --> 00:29:18,398
AND THEN YOU WENT AND YOU
WEIGHED THAT BOX...

525
00:29:18,399 --> 00:29:20,300
NOW YOU TAKE THE BOX,
YOU MAKE IT TWICE AS BIG.

526
00:29:20,301 --> 00:29:22,168
YOU DON'T OPEN IT.
YOU DON'T PUT ANYTHING IN IT.

527
00:29:22,169 --> 00:29:24,705
YOU WEIGH IT AGAIN, IT'S GONNA
WEIGH TWICE AS MUCH.

528
00:29:24,706 --> 00:29:27,041
THIS REMARKABLE
OBSERVATION MEANS

529
00:29:27,042 --> 00:29:30,511
THAT WE SHOULD BE SAFE
FROM A BIG RIP.

530
00:29:30,512 --> 00:29:33,947
DARK ENERGY WILL CONTINUE
TO INCREASE GRADUALLY.

531
00:29:33,948 --> 00:29:37,516
THE UNIVERSE IS HEADING
FOR A BIG FREEZE,

532
00:29:37,517 --> 00:29:41,554
AND SCIENTISTS CAN FINALLY
CALCULATE A TIMELINE

533
00:29:41,555 --> 00:29:44,425
FOR THE END OF EVERYTHING.

534
00:29:53,602 --> 00:29:55,137
IT NOW SEEMS
THAT WE LIVE

535
00:29:55,138 --> 00:29:57,772
IN AN ALMOST PERFECT UNIVERSE,

536
00:29:57,773 --> 00:30:01,342
WITH JUST ENOUGH GRAVITY
TO HOLD THE GALAXIES TOGETHER

537
00:30:01,343 --> 00:30:05,248
AND JUST ENOUGH DARK ENERGY
THAT IT WILL EXPAND FOREVER

538
00:30:05,249 --> 00:30:07,885
WITHOUT RIPPING ITSELF
TO SHREDS.

539
00:30:09,820 --> 00:30:14,492
COSMOLOGISTS CAN FINALLY
ENVISION THE END OF IT ALL.

540
00:30:15,826 --> 00:30:18,394
30 YEARS AGO,
IT WAS DEBATABLE.

541
00:30:18,395 --> 00:30:21,262
BUT NOW, IT APPEARS
THAT THE UNIVERSE MOST LIKELY

542
00:30:21,263 --> 00:30:22,831
WILL SUFFER A DEEP FREEZE.

543
00:30:22,832 --> 00:30:26,137
IF YOU LOOK AT THE DATA,
IT STARES OUT AT YOU.

544
00:30:27,303 --> 00:30:28,870
IN A BIG FREEZE,

545
00:30:28,871 --> 00:30:33,009
DARK ENERGY PUSHES GALAXIES
FURTHER AND FURTHER APART,

546
00:30:33,010 --> 00:30:35,880
BUT THEY REMAIN INTACT.

547
00:30:35,913 --> 00:30:39,583
THE STARS INSIDE THEM
FADE AWAY.

548
00:30:39,584 --> 00:30:42,119
EVERY STAR YOU SEE IN THE SKY,
INCLUDING OUR SUN,

549
00:30:42,120 --> 00:30:44,222
IS BURNING THROUGH
ITS NUCLEAR FUEL.

550
00:30:44,223 --> 00:30:47,423
THE GAS WILL RUN OUT,
STARS WILL STOP BEING MADE,

551
00:30:47,424 --> 00:30:51,062
AND THE ONES THAT EXIST ARE IT.
THOSE ARE THE LAST ONES.

552
00:30:55,467 --> 00:30:57,767
A HUNDRED TRILLION
YEARS FROM NOW,

553
00:30:57,768 --> 00:31:02,073
THE BIGGEST STARS WILL BE
THE FIRST TO GO EXTINCT.

554
00:31:02,074 --> 00:31:05,208
BIG STARS BURN BRIGHT
AND DIE HARD.

555
00:31:05,209 --> 00:31:09,647
THE STAR'S CORE COLLAPSES,

556
00:31:09,648 --> 00:31:11,784
UNLEASHING A SUPERNOVA.

557
00:31:13,084 --> 00:31:16,420
THEN GRAVITY CRUSHES
THE DEAD STAR DOWN

558
00:31:16,421 --> 00:31:19,090
TO A SINGLE DENSE SPOT.

559
00:31:19,091 --> 00:31:22,527
THE BRIGHT STAR
IS NOW A BLACK HOLE.

560
00:31:24,897 --> 00:31:27,467
SUN-LIKE STARS GO NEXT.

561
00:31:28,934 --> 00:31:31,535
AS THEIR SUPPLY OF HYDROGEN
RUNS OUT,

562
00:31:31,536 --> 00:31:33,905
THEY SWELL TO A BLOATED FIREBALL

563
00:31:33,906 --> 00:31:36,842
OVER 200 TIMES
THEIR CURRENT SIZE.

564
00:31:42,715 --> 00:31:44,950
AND WHEN THE CORE
HAS NO MORE HYDROGEN,

565
00:31:44,951 --> 00:31:48,220
IT'S GOING TO BLOAT UP
INTO A RED GIANT STAR.

566
00:31:48,221 --> 00:31:50,589
NOW, RED GIANT STARS ARE SO BIG,
THEY WILL ACTUALLY

567
00:31:50,590 --> 00:31:52,590
EAT UP THEIR OWN PLANETS.

568
00:31:52,591 --> 00:31:54,425
WE KNOW OF EXAMPLES
OF RED GIANTS

569
00:31:54,426 --> 00:31:56,494
THAT GO ALL THE WAY OUT
TO WHERE THE ORBIT OF JUPITER IS

570
00:31:56,495 --> 00:31:58,429
IN OUR SOLAR SYSTEM.

571
00:31:58,430 --> 00:32:01,399
ITS FUEL EXHAUSTED,

572
00:32:01,400 --> 00:32:04,102
THE SUN-LIKE STAR
GIVES IN TO GRAVITY

573
00:32:04,103 --> 00:32:06,204
AND SHRINKS TO A WHITE DWARF,

574
00:32:06,205 --> 00:32:07,973
A DENSE BALL OF MATTER

575
00:32:07,974 --> 00:32:11,108
JUST A FEW THOUSAND MILES
IN DIAMETER.

576
00:32:11,109 --> 00:32:15,147
IT WILL GLOW WITH HEAT
FOR A FURTHER 10 BILLION YEARS

577
00:32:15,148 --> 00:32:17,715
BEFORE COOLING TO A BLACK DWARF,

578
00:32:17,716 --> 00:32:22,755
A BALL OF COMPRESSED CARBON,
PERHAPS EVEN DIAMOND.

579
00:32:25,459 --> 00:32:27,793
AS THE BIGGEST STARS DIE,

580
00:32:27,794 --> 00:32:31,330
THE UNIVERSE
WILL SLOWLY TURN RED.

581
00:32:31,331 --> 00:32:33,098
THE BLUE STARS
WILL BLOW UP,

582
00:32:33,099 --> 00:32:35,267
AND THEN THE SLIGHTLY LESS BLUE
STARS WILL BLOW UP,

583
00:32:35,268 --> 00:32:37,636
AND THEN STARS LIKE THE SUN
WILL FADE AWAY AND DIE,

584
00:32:37,637 --> 00:32:40,308
LEAVING JUST THE RED STARS
TO EXIST.

585
00:32:41,876 --> 00:32:43,711
RED STARS
ARE THE SMALLEST

586
00:32:43,712 --> 00:32:45,613
AND COOLEST IN THE UNIVERSE.

587
00:32:45,614 --> 00:32:47,882
THEY BURN THEIR FUEL SLOWLY.

588
00:32:47,883 --> 00:32:50,616
BUT, AFTER ANOTHER
10 TRILLION YEARS,

589
00:32:50,617 --> 00:32:53,020
EVEN THESE SMALLEST
OF DWARF STARS

590
00:32:53,021 --> 00:32:55,289
WILL USE UP THEIR FUEL.

591
00:32:55,290 --> 00:32:58,858
STARS AS WE KNOW THEM
WILL CEASE TO BURN ENERGY,

592
00:32:58,859 --> 00:33:01,328
AND THE NIGHT SKY
WILL TURN BLACK.

593
00:33:01,329 --> 00:33:05,199
BLACK HOLES,
THE CORPSES OF DEAD STARS,

594
00:33:05,200 --> 00:33:09,838
AND COLD CLOUDS OF GAS AND DUST
ARE ALL THAT REMAINS.

595
00:33:11,640 --> 00:33:14,409
THE AGE OF STARS IS OVER.

596
00:33:14,410 --> 00:33:18,145
THE AGE OF BLACK HOLES BEGINS.

597
00:33:18,146 --> 00:33:20,348
BLACK HOLES BECOME
THE FUNDAMENTAL BUILDING BLOCK

598
00:33:20,349 --> 00:33:22,015
OF THE UNIVERSE.

599
00:33:22,016 --> 00:33:24,384
A GALAXY WILL BASICALLY BE
A SUPERMASSIVE BLACK HOLE

600
00:33:24,385 --> 00:33:26,419
IN THE CENTER, WITH SMALLER
BLACK HOLES ORBITING IT.

601
00:33:26,420 --> 00:33:28,955
IN SOME WAYS, IT'S KIND OF
A GHOST UNIVERSE.

602
00:33:28,956 --> 00:33:30,792
IT'S THE CORPSES,
THE ZOMBIE STARS,

603
00:33:30,793 --> 00:33:32,493
THAT WILL TAKE US
INTO THE FUTURE.

604
00:33:32,494 --> 00:33:35,663
ZOMBIE GALAXIES
FILLED WITH BLACK HOLES

605
00:33:35,664 --> 00:33:37,464
CONTINUE TO EVOLVE.

606
00:33:37,465 --> 00:33:40,835
THEY SWEEP UP THE DEAD REMAINS
OF STARS.

607
00:33:40,836 --> 00:33:44,939
BLACK HOLE MERGES
WITH BLACK HOLE.

608
00:33:44,940 --> 00:33:47,040
THEY'LL EAT EACH OTHER
AND THEY'LL GET BIGGER,

609
00:33:47,041 --> 00:33:48,875
AND MAYBE THEY'LL FALL INTO
THE SUPERMASSIVE BLACK HOLE

610
00:33:48,876 --> 00:33:50,344
AND IT'LL GET BIGGER.

611
00:33:50,345 --> 00:33:53,346
THE UNIVERSE WILL STILL BE
AN EXCITING, DYNAMIC PLACE,

612
00:33:53,347 --> 00:33:55,649
IT'S JUST THAT THE TIME SCALES
YOU'RE TALKING ABOUT

613
00:33:55,650 --> 00:33:57,218
ARE NOW TRILLIONS OF YEARS

614
00:33:57,219 --> 00:33:59,920
INSTEAD OF THOUSANDS
OR MILLIONS OF YEARS.

615
00:33:59,921 --> 00:34:04,091
ANY MATERIAL THAT
EVADES THE PULL OF A BLACK HOLE

616
00:34:04,092 --> 00:34:09,362
EVENTUALLY DIES AWAY
AS ITS PROTONS DISINTEGRATE.

617
00:34:09,363 --> 00:34:12,500
A PROTON, ONE OF THE FUNDAMENTAL
BUILDING BLOCKS

618
00:34:12,501 --> 00:34:15,335
OF ATOMIC MATTER,
OF WHAT MAKES US UP,

619
00:34:15,336 --> 00:34:17,837
CAN JUST SPONTANEOUSLY
FALL APART,

620
00:34:17,838 --> 00:34:21,710
AND IT TURNS OUT THIS TAKES
A<i> TREMENDOUSLY</i> LONG TIME.

621
00:34:21,711 --> 00:34:23,810
BUT EVEN THAT WILL GO AWAY.

622
00:34:23,811 --> 00:34:28,882
ALL THAT WILL BE LEFT
IS A SEA OF BLACK HOLES.

623
00:34:28,883 --> 00:34:32,152
SCIENTISTS USED TO THINK
BLACK HOLES WERE IMMORTAL,

624
00:34:32,153 --> 00:34:33,823
BUT EVEN THESE WILL ONE DAY DIE.

625
00:34:33,924 --> 00:34:36,625
NOW WE'RE TALKING ABOUT
TIME SCALES

626
00:34:36,626 --> 00:34:38,294
OF<i> UNIMAGINABLE</i> LENGTH --

627
00:34:38,295 --> 00:34:40,831
QUADRILLIONS OF YEARS
INTO THE FUTURE.

628
00:34:40,932 --> 00:34:42,398
BUT ON THAT TIME SCALE,

629
00:34:42,399 --> 00:34:46,501
EVEN THE BLACK HOLES
BEGIN TO EVAPORATE.

630
00:34:46,502 --> 00:34:48,738
THEY'LL GET SMALLER AND SMALLER
AND SMALLER,

631
00:34:48,739 --> 00:34:50,673
AND THEN, POOF, THEY'LL BE GONE.

632
00:34:50,674 --> 00:34:53,142
THE UNIVERSE WILL END

633
00:34:53,143 --> 00:34:55,977
WHEN THE LAST REMAINING
BLACK HOLE DIES.

634
00:34:55,978 --> 00:34:58,780
AS IT GETS SMALLER,
THE EVAPORATION RATE

635
00:34:58,781 --> 00:35:00,816
INCREASES EXPONENTIALLY.

636
00:35:00,817 --> 00:35:03,017
BEFORE LONG,
IT REACHES A SIZE

637
00:35:03,018 --> 00:35:08,023
A BILLIONTH OF A TRILLIONTH
OF A TRILLIONTH OF AN INCH.

638
00:35:08,024 --> 00:35:11,427
AT THAT INSTANT,
THE LAWS OF PHYSICS BREAK DOWN,

639
00:35:11,428 --> 00:35:15,597
AND THE LAST BLACK HOLE EXPLODES
IN A FLASH OF GAMMA RAYS,

640
00:35:15,598 --> 00:35:18,367
LEAVING NOTHING.

641
00:35:18,368 --> 00:35:21,970
AND IT WILL DIE
IN A SUDDEN BURST OF LIGHT,

642
00:35:21,971 --> 00:35:23,639
THE LAST BURST OF LIGHT

643
00:35:23,640 --> 00:35:25,975
IN THE ENTIRE HISTORY
OF THE UNIVERSE.

644
00:35:26,611 --> 00:35:28,612
THE BIG FREEZE IS COMING.

645
00:35:28,613 --> 00:35:32,916
THE UNIVERSE WILL SUFFER A COLD,
SLOW, DARK DEATH

646
00:35:32,917 --> 00:35:34,284
WHICH WILL PLAY OUT

647
00:35:34,285 --> 00:35:38,021
OVER TRILLIONS UPON TRILLIONS
OF YEARS.

648
00:35:38,022 --> 00:35:41,425
BUT QUANTUM PHYSICS LEAVES
THE DOOR OPEN

649
00:35:41,426 --> 00:35:43,193
FOR AN ALTERNATIVE END,

650
00:35:43,194 --> 00:35:46,630
AN EVENT SO POWERFUL,
SO DESTRUCTIVE,

651
00:35:46,631 --> 00:35:52,336
THAT IT COULD DESTROY EVERYTHING
WE SEE IN THE BLINK OF AN EYE.

652
00:35:52,337 --> 00:35:55,507
AND IT COULD HAPPEN TOMORROW.

653
00:36:04,751 --> 00:36:06,585
THE END OF THE UNIVERSE --

654
00:36:06,586 --> 00:36:08,118
IT'S COMING.

655
00:36:08,119 --> 00:36:11,522
DARK ENERGY ACCELERATES
THE SPACE BETWEEN GALAXIES,

656
00:36:11,523 --> 00:36:15,093
PUSHING EVERYTHING WE SEE
TO A LONG, COLD,

657
00:36:15,094 --> 00:36:17,830
AND VERY SLOW DEATH.

658
00:36:17,831 --> 00:36:21,699
UNLESS, THAT IS, SOMETHING
BIZARRE HAPPENS FIRST.

659
00:36:21,700 --> 00:36:25,504
A MONSTER CALLED
PHASE TRANSITION

660
00:36:25,505 --> 00:36:27,138
IS LURKING IN THE SHADOWS,

661
00:36:27,139 --> 00:36:31,076
AND IT COULD ANNIHILATE
THE FABRIC OF SPACE AND TIME

662
00:36:31,077 --> 00:36:34,178
AT ANY MOMENT.

663
00:36:34,179 --> 00:36:37,949
WHEN WE COOL DOWN WATER,
IT TURNS INTO ICE.

664
00:36:37,950 --> 00:36:39,451
THE PROPERTIES CHANGE.

665
00:36:39,452 --> 00:36:41,654
IF YOU LIVED IN THE WATER,
WHEN IT CHANGED TO ICE,

666
00:36:41,655 --> 00:36:43,489
YOUR WORLD
WOULD BE VERY DIFFERENT.

667
00:36:43,490 --> 00:36:48,694
WATER PHASE CHANGES
INTO ICE WHEN IT LOSES ENERGY.

668
00:36:48,695 --> 00:36:51,730
I ONCE LEFT A WATER
BOTTLE IN MY CAR OVERNIGHT.

669
00:36:51,731 --> 00:36:54,632
IT WAS STILL LIQUID,
BUT THE MOMENT I TOUCHED IT,

670
00:36:54,633 --> 00:36:56,033
THE SLIGHT IMPERFECTION,

671
00:36:56,034 --> 00:36:57,902
THE LITTLE BIT OF ICE
THAT IT FORMED, SPREAD,

672
00:36:57,903 --> 00:36:59,770
POOF, AND FILLED UP
THE WHOLE BOTTLE.

673
00:36:59,771 --> 00:37:02,974
THAT RAPID CHANGE
TO SOMETHING NEW

674
00:37:02,975 --> 00:37:05,144
IS CALLED A PHASE TRANSITION,

675
00:37:05,145 --> 00:37:10,548
AND BIZARRELY, THE SAME THING
COULD HAPPEN TO EMPTY SPACE.

676
00:37:10,549 --> 00:37:13,253
WE'VE REALLY COME TO UNDERSTAND

677
00:37:13,254 --> 00:37:16,456
THAT WE SHOULDN'T TAKE
FOR GRANTED THAT...VACUUM,

678
00:37:16,457 --> 00:37:19,191
WHAT WE CALL NOTHING,
IS ACTUALLY STABLE.

679
00:37:19,192 --> 00:37:22,094
IT COULD BE THAT THE ENERGY
STORED IN EMPTY SPACE

680
00:37:22,095 --> 00:37:24,898
IS JUST WAITING TO BE RELEASED
IN A PHASE TRANSITION.

681
00:37:24,899 --> 00:37:28,035
IF IT IS, THE LAWS OF PHYSICS
WILL CHANGE.

682
00:37:29,904 --> 00:37:33,606
A SPONTANEOUS GLITCH
IN THE FABRIC OF SPACE-TIME

683
00:37:33,607 --> 00:37:37,510
COULD TRIGGER
A PHASE TRANSITION OF SPACE,

684
00:37:37,511 --> 00:37:41,914
A TINY BUBBLE OF NEW UNIVERSE
THAT SPREADS OUT,

685
00:37:41,915 --> 00:37:44,215
OVERWRITING THE OLD.

686
00:37:44,216 --> 00:37:47,887
WE KNOW IT CAN HAPPEN,
BECAUSE IT'S HAPPENED BEFORE.

687
00:37:51,692 --> 00:37:53,693
AT THE MOMENT OF THE BIG BANG,

688
00:37:53,694 --> 00:37:55,762
THE UNIVERSE
THAT'S FIRST CREATED

689
00:37:55,763 --> 00:37:59,132
IS COMPLETELY DIFFERENT
TO THE ONE WE SEE TODAY.

690
00:37:59,133 --> 00:38:02,068
HOT AND WITHOUT FORM,

691
00:38:02,069 --> 00:38:04,670
THERE'S NO MATTER, NO TIME.

692
00:38:04,671 --> 00:38:08,240
THE LAWS OF PHYSICS
ARE DIFFERENT.

693
00:38:08,241 --> 00:38:11,945
SUDDENLY, LESS THAN A TRILLIONTH
OF A SECOND LATER,

694
00:38:11,946 --> 00:38:15,014
A GLITCH TRIGGERS
A PHASE TRANSITION.

695
00:38:15,015 --> 00:38:18,652
A TINY BUBBLE OF THE UNIVERSE
WE LIVE IN TODAY FORMS,

696
00:38:18,653 --> 00:38:20,887
AND IT RACES OUTWARD,

697
00:38:20,888 --> 00:38:22,856
DESTROYING EVERYTHING IT TOUCHES

698
00:38:22,857 --> 00:38:26,025
LIKE ICE
SPREADING THROUGH WATER.

699
00:38:26,026 --> 00:38:29,762
THE ENERGY THAT SPILLS OUT
CREATES THE SPACE AND TIME

700
00:38:29,763 --> 00:38:31,398
THAT WE EXIST IN,

701
00:38:31,399 --> 00:38:36,003
THE BUILDING BLOCKS OF MATTER
AND THE FORCES THAT GOVERN THEM.

702
00:38:36,004 --> 00:38:38,739
ALL THAT ENERGY WAS RELEASED,
PRODUCING ALL THE MATTER

703
00:38:38,740 --> 00:38:40,675
AND RADIATION WE OBSERVE
IN THE UNIVERSE TODAY.

704
00:38:40,875 --> 00:38:43,711
THE OLD UNIVERSE
GIVES UP ITS ENERGY

705
00:38:43,712 --> 00:38:45,347
TO CREATE THE NEW.

706
00:38:45,348 --> 00:38:47,482
BUT IT HOLDS SOME BACK.

707
00:38:47,483 --> 00:38:51,919
THE VACUUM OF SPACE
STILL HAS ENERGY BOUND TO IT.

708
00:38:51,920 --> 00:38:56,457
PERHAPS THIS IS THE DARK ENERGY
WE SEE TODAY.

709
00:38:56,458 --> 00:38:59,761
PHYSICISTS BELIEVE
THAT SOMEDAY IN THE FUTURE,

710
00:38:59,762 --> 00:39:03,263
A BRAND NEW GLITCH IN THE FABRIC
OF SPACE-TIME

711
00:39:03,264 --> 00:39:05,800
MAY TRIGGER ANOTHER
PHASE TRANSITION,

712
00:39:05,801 --> 00:39:09,370
ONE THAT WIPES US
AND EVERYTHING WE SEE

713
00:39:09,371 --> 00:39:11,305
OUT OF EXISTENCE.

714
00:39:11,306 --> 00:39:14,809
THIS IS A WAY TO DESTROY
AN ENTIRE UNIVERSE,

715
00:39:14,810 --> 00:39:16,577
BECAUSE WITHIN YOUR UNIVERSE

716
00:39:16,578 --> 00:39:19,079
ARE THE SEEDS
OF ITS OWN DESTRUCTION.

717
00:39:19,080 --> 00:39:22,050
IT WOULD SPREAD OUT AT THE SPEED
OF LIGHT IN A DEATH BUBBLE,

718
00:39:22,051 --> 00:39:25,019
RUINING ALL THE GALAXIES
AS IT PASSES THROUGH,

719
00:39:25,020 --> 00:39:28,322
AND ULTIMATELY COMPLETELY
DESTROYING OUR UNIVERSE.

720
00:39:28,323 --> 00:39:31,827
NOTHING CAN SURVIVE
THE EXPANDING PHASE TRANSITION.

721
00:39:31,828 --> 00:39:36,632
PLANETS, NEBULAS, GALAXIES --
ALL ARE RIPPED APART

722
00:39:36,633 --> 00:39:38,934
AS THE BOUNDARY
OF THE BUBBLE REACHES THEM.

723
00:39:38,935 --> 00:39:42,170
INSIDE THIS BUBBLE,
PROTONS ARE UNSTABLE,

724
00:39:42,171 --> 00:39:46,007
ATOMS BEGIN TO REARRANGE
IN A NEW FORM OF MATTER.

725
00:39:46,008 --> 00:39:48,043
AS THESE BUBBLES
BEGIN TO EXPAND,

726
00:39:48,044 --> 00:39:50,679
A NEW UNIVERSE IS BEING BORN

727
00:39:50,680 --> 00:39:53,347
IN THE CORPSE
OF THE OLD UNIVERSE,

728
00:39:53,348 --> 00:39:56,686
AND THE BEGINNING
OF A NEW LAW OF PHYSICS.

729
00:39:56,887 --> 00:40:00,522
AND SO, THE EXPANDING UNIVERSE
WE NOW SEE

730
00:40:00,523 --> 00:40:03,960
MAY END IN A PHASE TRANSITION,
BUT WE WON'T KNOW WHAT HIT US,

731
00:40:03,961 --> 00:40:05,895
'CAUSE THE LAWS OF PHYSICS
WILL CHANGE,

732
00:40:05,896 --> 00:40:08,631
AND WE WILL ESSENTIALLY MOST
LIKELY DISAPPEAR

733
00:40:08,632 --> 00:40:10,399
AT THE INSTANT IT HAPPENS.

734
00:40:10,400 --> 00:40:14,069
THIS BUBBLE WILL EXPAND
AT THE SPEED OF LIGHT,

735
00:40:14,070 --> 00:40:15,939
AND AS THE BUBBLE PASSES YOU,

736
00:40:15,940 --> 00:40:18,975
ALL THE ATOMS OF YOUR BODY
REARRANGE THEMSELVES,

737
00:40:18,976 --> 00:40:20,678
AND YOU WOULD NEVER KNOW IT.

738
00:40:20,679 --> 00:40:23,379
YOU WOULD HAVE NO WARNING,
BECAUSE THE BUBBLE ITSELF

739
00:40:23,380 --> 00:40:24,948
IS EXPANDING
AT THE SPEED OF LIGHT.

740
00:40:24,949 --> 00:40:27,552
YOU CAN'T PREDICT PRECISELY
WHEN IT COULD HAPPEN.

741
00:40:27,553 --> 00:40:29,184
YOU ONLY HAVE A PROBABILITY.

742
00:40:29,185 --> 00:40:31,421
SO WHAT YOU REALLY
ARE PREDICTING IS A RATE.

743
00:40:31,422 --> 00:40:34,592
DOES IT HAPPEN ONCE A YEAR?
ONCE EVERY 10 BILLION YEARS?

744
00:40:34,593 --> 00:40:36,825
ONCE EVERY GOOGOL YEARS?
OR WHATEVER.

745
00:40:36,826 --> 00:40:40,128
IT'S VERY POSSIBLE THAT
THESE BUBBLES GET NUCLEATED

746
00:40:40,129 --> 00:40:43,767
AND GROW ABOUT ONCE EVERY
10 OR 20 BILLION YEARS.

747
00:40:43,768 --> 00:40:46,403
SO IT HASN'T HAPPENED YET
BECAUSE WE GOT LUCKY.

748
00:40:46,404 --> 00:40:49,340
IT'S UNLIKELY IT WOULD HAPPEN
THE NEXT YEAR OR THE NEXT DAY,

749
00:40:49,341 --> 00:40:51,408
BUT THE LAWS OF PHYSICS
ABSOLUTELY ALLOW IT.

750
00:40:54,745 --> 00:40:59,016
A PHASE CHANGE
MAY HAPPEN, OR IT MAY NOT.

751
00:41:00,150 --> 00:41:04,290
THE UNIVERSE PLAYS ITS CARDS
CLOSE TO ITS CHEST.

752
00:41:08,125 --> 00:41:11,329
AND, LIKE DARK ENERGY
AND DARK MATTER,

753
00:41:11,330 --> 00:41:13,299
THERE MAY BE MORE SURPRISES
TO COME...

754
00:41:15,100 --> 00:41:19,970
...SURPRISES THAT WILL ONLY
ADD TO THE MYSTERY AND WONDER

755
00:41:19,971 --> 00:41:22,608
OUR UNIVERSE HOLDS FOR US.

756
00:41:25,978 --> 00:41:27,613
WHATEVER THE UNIVERSE
IS UP TO,

757
00:41:27,614 --> 00:41:28,979
WE STILL DON'T KNOW ENOUGH.

758
00:41:28,980 --> 00:41:31,082
WE'RE IN AN AGE OF DISCOVERY
RIGHT NOW.

759
00:41:31,083 --> 00:41:32,983
PERHAPS THERE IS SOMETHING ELSE
OUT THERE

760
00:41:32,984 --> 00:41:34,352
THAT WE DON'T KNOW ABOUT.

761
00:41:34,353 --> 00:41:36,755
SO, I'M NOT GOING TO DRAW
ANY CONCLUSIONS

762
00:41:36,756 --> 00:41:38,457
UNTIL THINGS ARE CONCLUSIVE.

763
00:41:41,159 --> 00:41:43,660
WE DON'T UNDERSTAND
THE NATURE OF DARK ENERGY.

764
00:41:43,661 --> 00:41:47,265
AND WITHOUT THAT UNDERSTANDING,
VIRTUALLY ANYTHING IS POSSIBLE.

765
00:41:47,266 --> 00:41:49,300
THE FUTURE IS STILL UNCERTAIN,

766
00:41:49,301 --> 00:41:51,635
AND THAT MEANS
THERE'S STILL A MYSTERY.

767
00:41:51,636 --> 00:41:55,007
AND FOR ME, THAT'S THE MOST
EXCITING POSSIBILITY OF ALL.