1 00:00:02,535 --> 00:00:07,598 Freeman: Space - it seems like it must go on forever. 2 00:00:07,674 --> 00:00:09,403 But does it? 3 00:00:09,476 --> 00:00:12,502 Out there in the farthest depths of the Universe, 4 00:00:12,579 --> 00:00:14,376 might there be some place 5 00:00:14,447 --> 00:00:17,883 where something turns into absolutely nothing? 6 00:00:20,887 --> 00:00:24,516 Scientists are probing the far-flung reaches of the cosmos, 7 00:00:24,591 --> 00:00:27,059 trying to detect that outer limit, 8 00:00:27,127 --> 00:00:30,096 to find the shape of space. 9 00:00:35,668 --> 00:00:38,831 Now surprising evidence suggests 10 00:00:38,905 --> 00:00:42,033 that not only is there a place where the Universe ends, 11 00:00:42,108 --> 00:00:45,271 but that there might be something lurking beyond it - 12 00:00:45,345 --> 00:00:49,748 something unimaginably alien. 13 00:00:56,056 --> 00:01:00,925 Space, time, life itself. 14 00:01:03,029 --> 00:01:07,693 The secrets of the cosmos lie Through the Wormhole. 15 00:01:19,179 --> 00:01:23,946 Once in a while, a really big idea comes along - 16 00:01:24,017 --> 00:01:28,283 one that completely changes our concept of who we are. 17 00:01:28,354 --> 00:01:32,290 In 1543, Nicolas Copernicus proved that the Earth 18 00:01:32,358 --> 00:01:35,725 was not at the center of the cosmos. 19 00:01:35,795 --> 00:01:38,525 In the 1920s, Edwin Hubble saw 20 00:01:38,598 --> 00:01:40,566 that all the galaxies in the Universe 21 00:01:40,633 --> 00:01:43,124 were rushing away from one another, 22 00:01:43,203 --> 00:01:45,194 sparking the idea 23 00:01:45,271 --> 00:01:48,365 that the Universe had not been here forever 24 00:01:48,441 --> 00:01:51,877 but was created in one explosive moment - 25 00:01:51,945 --> 00:01:53,674 the Big Bang. 26 00:01:53,746 --> 00:01:58,274 Now another monumental change is upon us. 27 00:01:58,351 --> 00:02:03,186 We've long imagined the Universe to be infinite in size, 28 00:02:03,256 --> 00:02:07,784 but many cosmologists now think the Universe... 29 00:02:07,861 --> 00:02:09,328 is finite. 30 00:02:09,395 --> 00:02:13,491 Some believe they even know its shape. 31 00:02:13,566 --> 00:02:16,364 If we do discover an edge to the Universe, 32 00:02:16,436 --> 00:02:17,960 we'll have to grapple 33 00:02:18,037 --> 00:02:22,235 with another very challenging and unsettling question. 34 00:02:22,308 --> 00:02:25,607 What lies beyond the edge? 35 00:02:28,114 --> 00:02:30,708 Every day on my way home from school, 36 00:02:30,783 --> 00:02:33,411 I used to pass a long wall. 37 00:02:33,486 --> 00:02:37,752 It was at least twice my height. 38 00:02:37,824 --> 00:02:40,349 I had no chance of seeing over it, 39 00:02:40,426 --> 00:02:44,362 but I could hear strange sounds coming from behind it. 40 00:02:44,430 --> 00:02:47,297 My mind ran wild 41 00:02:47,367 --> 00:02:51,895 imagining what might be back there. 42 00:02:51,971 --> 00:02:54,201 Wild animals? Outlaws? 43 00:02:54,274 --> 00:02:58,210 Or some fearsome monster? 44 00:02:58,278 --> 00:03:00,610 I would press my ear up against it 45 00:03:00,680 --> 00:03:03,547 to try and decipher what it could be. 46 00:03:03,616 --> 00:03:08,144 I never did find out, but I never stopped wondering. 47 00:03:10,523 --> 00:03:14,323 Neil Cornish is a cosmologist 48 00:03:14,394 --> 00:03:19,263 who lives and works in the big sky country of Montana. 49 00:03:19,332 --> 00:03:21,163 The only walls out here 50 00:03:21,234 --> 00:03:25,034 are fences to keep his horses from roaming off. 51 00:03:25,104 --> 00:03:28,096 Neil is the latest in a long line of thinkers 52 00:03:28,174 --> 00:03:31,075 to contemplate the size of the Universe. 53 00:03:31,144 --> 00:03:34,705 The first we know of was a Greek philosopher king 54 00:03:34,781 --> 00:03:37,614 called Architus. 55 00:03:37,684 --> 00:03:39,174 The Greek philosopher Architus 56 00:03:39,252 --> 00:03:42,187 offered an argument for why the Universe must be infinite. 57 00:03:42,255 --> 00:03:45,281 He said, "If I was to go out to the edge of the Universe 58 00:03:45,358 --> 00:03:47,826 and then extend my staff to here, 59 00:03:47,894 --> 00:03:50,590 that would now be the edge of the Universe. 60 00:03:50,663 --> 00:03:53,188 And then, if I was to extend my staff to here, 61 00:03:53,266 --> 00:03:55,996 that would now be the new edge of the Universe. 62 00:03:56,069 --> 00:03:58,503 And if I was to extend my staff out to here, 63 00:03:58,571 --> 00:04:00,971 that would now be the edge of the Universe. 64 00:04:01,040 --> 00:04:03,770 So the Universe must be infinite." 65 00:04:03,843 --> 00:04:07,108 Freeman: Architus's mental game set the tone 66 00:04:07,180 --> 00:04:10,240 for over 2,000 years of scientific dogma - 67 00:04:10,316 --> 00:04:13,547 our Universe must be infinitely large 68 00:04:13,620 --> 00:04:15,611 and has existed forever. 69 00:04:15,688 --> 00:04:19,556 But that dogma is now being challenged. 70 00:04:19,626 --> 00:04:21,992 So, one problem with an infinite Universe 71 00:04:22,061 --> 00:04:24,029 that's not just infinite in space 72 00:04:24,097 --> 00:04:26,793 but also infinite in time - has no beginning - 73 00:04:26,866 --> 00:04:28,834 you have an infinite number of stars. 74 00:04:28,901 --> 00:04:31,893 So the sky would be just completely covered in white, 75 00:04:31,971 --> 00:04:35,429 bright, bright - so bright that it would fry you. 76 00:04:35,508 --> 00:04:37,976 So, when we look out at night, that's not what we see. 77 00:04:38,044 --> 00:04:39,306 We see a star here or there 78 00:04:39,379 --> 00:04:41,404 and then, essentially, darkness all around. 79 00:04:41,481 --> 00:04:42,880 So this tells us something. 80 00:04:42,949 --> 00:04:45,577 It tells us we don't live in an infinite Universe 81 00:04:45,652 --> 00:04:46,812 that's infinitely old. 82 00:04:46,886 --> 00:04:49,218 Freeman: It was our dark sky 83 00:04:49,289 --> 00:04:52,656 that inspired a revolutionary idea about the cosmos - 84 00:04:52,725 --> 00:04:56,092 that it cannot have been here forever. 85 00:04:56,162 --> 00:04:59,427 The Big Bang - 86 00:04:59,499 --> 00:05:03,196 a moment where all the space and matter we can see 87 00:05:03,269 --> 00:05:05,362 burst into existence, 88 00:05:05,438 --> 00:05:08,339 expanding out from a single point. 89 00:05:10,576 --> 00:05:12,476 But the Big Bang creates a problem 90 00:05:12,545 --> 00:05:15,412 for astronomers searching for the edge of the Universe. 91 00:05:15,481 --> 00:05:17,847 Because it takes light time 92 00:05:17,917 --> 00:05:20,249 to travel across the vastness of space, 93 00:05:20,320 --> 00:05:23,118 astronomers were always looking back in time, 94 00:05:23,189 --> 00:05:26,989 and, eventually, they run out of time. 95 00:05:27,060 --> 00:05:29,153 Cornish: So, when we look out at the stars at night, 96 00:05:29,228 --> 00:05:32,391 we're seeing those stars as they were years ago. 97 00:05:32,465 --> 00:05:34,558 The nearby stars, maybe a few years ago. 98 00:05:34,634 --> 00:05:37,194 Looking out across the galaxy, thousands of years ago. 99 00:05:37,270 --> 00:05:38,669 And going back and back, 100 00:05:38,738 --> 00:05:42,037 we see galaxies back billions of years ago. 101 00:05:42,108 --> 00:05:44,736 And then, beyond that, where we see no more galaxies. 102 00:05:44,811 --> 00:05:46,335 13 billion years ago 103 00:05:46,412 --> 00:05:48,812 is the next thing that we've managed to image, 104 00:05:48,881 --> 00:05:52,510 and it is the after-glow of the Big Bang. 105 00:05:52,585 --> 00:05:55,850 Freeman: It's called the Cosmic Microwave Background, 106 00:05:55,922 --> 00:05:58,720 and it's a picture of the way the Universe looked 107 00:05:58,791 --> 00:06:02,386 about 400,000 years after the Big Bang. 108 00:06:02,462 --> 00:06:05,556 Cornish: The Universe is filled with this hot gas, this hot plasma. 109 00:06:05,631 --> 00:06:07,861 Light really can't go anywhere. 110 00:06:07,934 --> 00:06:10,266 So we can't see any further back, 111 00:06:10,336 --> 00:06:12,736 just as we can't see into the sun. 112 00:06:12,805 --> 00:06:16,332 Freeman: The Cosmic Microwave Background 113 00:06:16,409 --> 00:06:19,173 is a barrier that blocks our vision. 114 00:06:19,245 --> 00:06:22,510 Behind it, there could be an edge. 115 00:06:22,582 --> 00:06:26,279 Or perhaps the Universe does extend on forever. 116 00:06:26,352 --> 00:06:29,879 But no matter how powerful our telescopes become, 117 00:06:29,956 --> 00:06:34,052 that domain will never be visible. 118 00:06:38,664 --> 00:06:40,723 But there might be another way to discover 119 00:06:40,800 --> 00:06:43,291 if the Universe has an edge. 120 00:06:43,369 --> 00:06:45,132 Janna Levin is a theoretician 121 00:06:45,204 --> 00:06:48,367 who uses complex numerical simulations 122 00:06:48,441 --> 00:06:52,844 to solve some of science's most challenging problems. 123 00:06:56,616 --> 00:06:59,050 It might surprise you that a game as old as "Asteroids" 124 00:06:59,118 --> 00:07:01,018 can teach us something about the Universe, 125 00:07:01,087 --> 00:07:02,884 but there's a rule in the game 126 00:07:02,955 --> 00:07:05,321 to make a world out of the game that makes sense, 127 00:07:05,391 --> 00:07:08,326 where, if you exit the top, you re-enter the bottom, 128 00:07:08,394 --> 00:07:11,295 or if you exit the left, you re-enter from the right. 129 00:07:11,364 --> 00:07:13,161 And that rule makes this world 130 00:07:13,232 --> 00:07:15,393 in which you're playing the game, 131 00:07:15,468 --> 00:07:17,197 this space in which you're playing the game, 132 00:07:17,270 --> 00:07:18,862 a finite space. 133 00:07:18,938 --> 00:07:20,098 And that's kind of like 134 00:07:20,173 --> 00:07:21,936 the rules we're imagining for the Universe. 135 00:07:22,008 --> 00:07:24,806 Freeman: If our Universe is finite, 136 00:07:24,877 --> 00:07:28,608 scientists believe its edges must also be linked, 137 00:07:28,681 --> 00:07:30,478 that the entire cosmos 138 00:07:30,550 --> 00:07:34,042 must act like a giant game of "Asteroids." 139 00:07:34,120 --> 00:07:37,487 If we could bend this space, 140 00:07:37,557 --> 00:07:40,424 we would see that it looks like something more intuitive. 141 00:07:40,493 --> 00:07:43,018 Like, for example, if I were to take this menu 142 00:07:43,095 --> 00:07:45,154 and apply that rule from the "Asteroid" game. 143 00:07:45,231 --> 00:07:47,256 You know, I exit the top, I enter the bottom. 144 00:07:47,333 --> 00:07:49,767 That's exactly the same as taking the menu 145 00:07:49,836 --> 00:07:52,805 and rolling it up and gluing the sides together. 146 00:07:52,872 --> 00:07:54,533 It gives the same effect. 147 00:07:54,607 --> 00:07:58,373 And if I could bend this rather too stiff menu, 148 00:07:58,444 --> 00:07:59,877 I would try to bend it 149 00:07:59,946 --> 00:08:03,245 so that the two edges came together and were glued. 150 00:08:03,316 --> 00:08:05,375 And then I'd be making something kind of like, 151 00:08:05,451 --> 00:08:07,919 you know, a bagel - a classic, New York bagel. 152 00:08:07,987 --> 00:08:11,354 And the bagel is glued together not just like a cylinder 153 00:08:11,424 --> 00:08:13,255 but also around the other side. 154 00:08:13,326 --> 00:08:17,922 Freeman: Even though the surface of this bagel is clearly finite, 155 00:08:17,997 --> 00:08:21,398 no one living in this space would ever run into an edge, 156 00:08:21,467 --> 00:08:24,402 so it feels boundless and infinite. 157 00:08:24,470 --> 00:08:26,233 When we live inside the Universe, 158 00:08:26,305 --> 00:08:28,102 we can't step outside of it. 159 00:08:28,174 --> 00:08:30,506 There's no other dimension to look down from, 160 00:08:30,576 --> 00:08:34,171 onto our 3-dimensional Universe, so it's harder to visualize. 161 00:08:34,247 --> 00:08:35,908 But we can use the rules 162 00:08:35,982 --> 00:08:39,418 like the rules that are used in the "Asteroids" game. 163 00:08:39,485 --> 00:08:41,248 And then we add one more rule 164 00:08:41,320 --> 00:08:43,185 for three rules for three dimensions. 165 00:08:43,256 --> 00:08:47,124 Go out the back face, come in the front. 166 00:08:47,193 --> 00:08:50,219 Freeman: If we do live in a cosmic asteroid cube, 167 00:08:50,296 --> 00:08:53,356 there is a way we could discover the edges - 168 00:08:53,432 --> 00:08:55,627 not by flying a spaceship across them, 169 00:08:55,701 --> 00:08:57,692 but by standing still 170 00:08:57,770 --> 00:09:02,036 and watching light as it wraps around the Universe. 171 00:09:02,108 --> 00:09:04,804 If the Universe were the size of a room 172 00:09:04,877 --> 00:09:08,540 and you stood in the middle of it holding up a lantern, 173 00:09:08,614 --> 00:09:11,276 light beaming out from your back 174 00:09:11,350 --> 00:09:12,840 would zip out one wall 175 00:09:12,919 --> 00:09:15,752 and re-enter the room from the other side 176 00:09:15,821 --> 00:09:17,914 so you'd see an image of your back 177 00:09:17,990 --> 00:09:19,582 on the wall in front of you. 178 00:09:19,659 --> 00:09:21,627 Looking out to the right, 179 00:09:21,694 --> 00:09:25,152 you'd see light coming from your left side. 180 00:09:25,231 --> 00:09:28,325 The room would appear to be covered in mirrors. 181 00:09:28,401 --> 00:09:33,304 Whichever wall you looked at, you'd see an image of yourself. 182 00:09:33,372 --> 00:09:36,398 When we look at the night sky, 183 00:09:36,475 --> 00:09:38,841 we don't see this hall of mirrors. 184 00:09:38,911 --> 00:09:41,141 But space is so vast, 185 00:09:41,213 --> 00:09:43,340 light could take billions of years 186 00:09:43,416 --> 00:09:45,316 to loop around the Universe. 187 00:09:45,384 --> 00:09:48,547 Space and time on this epic scale 188 00:09:48,621 --> 00:09:52,250 mean that mirror images would look nothing like one another. 189 00:09:52,325 --> 00:09:56,159 So, imagine this corral is our Universe. 190 00:09:56,228 --> 00:10:01,165 There will be repeats of this corral ad infinitum, 191 00:10:01,233 --> 00:10:04,999 giving an illusion that we live in an infinite space. 192 00:10:05,071 --> 00:10:07,938 But if this corral were just 30 light-years across, 193 00:10:08,007 --> 00:10:10,032 when I look out there, 194 00:10:10,109 --> 00:10:12,669 I wouldn't see myself as I am now. 195 00:10:12,745 --> 00:10:14,770 I'd see myself as a 10-year-old boy 196 00:10:14,847 --> 00:10:18,544 'cause I'd be looking 30 years back in time. 197 00:10:18,618 --> 00:10:23,055 Freeman: Our Milky Way is around 13 billion years old. 198 00:10:23,122 --> 00:10:27,354 It's been around almost as long as the Universe itself. 199 00:10:27,426 --> 00:10:29,758 Could a distant image of the Milky Way 200 00:10:29,829 --> 00:10:32,127 be hidden somewhere in the night sky, 201 00:10:32,198 --> 00:10:36,601 disguised the way it looked 5 or 10 billion years ago? 202 00:10:36,669 --> 00:10:42,107 If it is, how would we even recognize this youthful twin? 203 00:10:46,045 --> 00:10:51,176 This scientist believes the cosmos is a hall of mirrors, 204 00:10:51,250 --> 00:10:53,480 that the Universe is finite, 205 00:10:53,552 --> 00:10:57,044 and that he knows its size and shape. 206 00:11:02,995 --> 00:11:05,088 Imagine if the entire Universe 207 00:11:05,164 --> 00:11:07,928 was just the size of this room 208 00:11:08,000 --> 00:11:11,697 and that space wrapped around itself 209 00:11:11,771 --> 00:11:15,502 so each wall was the passageway to the wall opposite. 210 00:11:15,574 --> 00:11:19,237 Looking around, I would see myself fractured, 211 00:11:19,311 --> 00:11:22,712 as if by a crystal, into multiple copies, 212 00:11:22,782 --> 00:11:26,081 and each version would be slipped backward in time. 213 00:11:26,152 --> 00:11:28,310 Backward in time. 214 00:11:28,387 --> 00:11:31,254 Is our Universe a hall of mirrors? 215 00:11:35,094 --> 00:11:36,391 Astronomers have looked 216 00:11:36,462 --> 00:11:38,692 for repeating patterns of galaxies for years, 217 00:11:38,764 --> 00:11:42,359 looking for evidence that the Universe has an edge. 218 00:11:42,435 --> 00:11:45,063 But they've never found any. 219 00:11:50,476 --> 00:11:52,740 Jean-Pierre Luminet is a senior scientist 220 00:11:52,812 --> 00:11:55,713 at the Paris Observatory. 221 00:11:55,781 --> 00:11:57,749 He's been fascinated with the shape of space 222 00:11:57,817 --> 00:11:59,876 ever since he was a child. 223 00:11:59,952 --> 00:12:03,649 I was always interested in shapes created by nature. 224 00:12:03,723 --> 00:12:06,283 And while it's a nice idea 225 00:12:06,358 --> 00:12:10,658 to imagine a typical snail with a spiral, for instance - 226 00:12:10,730 --> 00:12:12,721 and you know there are spiral galaxies, for instance - 227 00:12:12,798 --> 00:12:15,631 the question is, 228 00:12:15,701 --> 00:12:18,727 why is this shape gonna be also in the sky? 229 00:12:18,804 --> 00:12:20,271 Freeman: Jean-Pierre's passion 230 00:12:20,339 --> 00:12:22,398 to discover the shape of the cosmos 231 00:12:22,475 --> 00:12:24,443 grew from the groundbreaking work 232 00:12:24,510 --> 00:12:26,569 of the great Albert Einstein. 233 00:12:26,645 --> 00:12:28,442 His theory of relativity 234 00:12:28,514 --> 00:12:31,506 showed that space is a flexible fabric 235 00:12:31,584 --> 00:12:35,020 whose shape is deformed by matter and energy. 236 00:12:35,087 --> 00:12:38,750 Einstein imagined the Universe as a flat sheet, 237 00:12:38,824 --> 00:12:41,054 stretching out to infinity. 238 00:12:41,127 --> 00:12:43,493 But there's no reason it can't also be finite 239 00:12:43,562 --> 00:12:45,462 and curled up on itself. 240 00:12:50,402 --> 00:12:53,462 Jean-Pierre realized he might be able to tell the difference 241 00:12:53,539 --> 00:12:56,030 between a finite and infinite Universe 242 00:12:56,108 --> 00:13:00,807 by thinking of the cosmos as a giant musical instrument. 243 00:13:00,880 --> 00:13:04,839 The Cosmic Microwave Background image 244 00:13:04,917 --> 00:13:10,048 shows us the Universe the way it was 13.7 billion years ago - 245 00:13:10,122 --> 00:13:14,923 a hot liquid vibrating with aftershocks of the Big Bang, 246 00:13:14,994 --> 00:13:17,224 like water rippling in a bathtub. 247 00:13:17,296 --> 00:13:19,127 So in some way, 248 00:13:19,198 --> 00:13:23,134 the Universe vibrated like a piano or like a drum. 249 00:13:23,202 --> 00:13:25,170 So, for instance, this is equivalent for the Big Bang. 250 00:13:27,473 --> 00:13:33,207 It's a complicated mixture of many harmonics, okay? 251 00:13:33,279 --> 00:13:35,907 And now we have the fundamental harmonics, 252 00:13:35,981 --> 00:13:37,778 which gives the pitch. 253 00:13:37,850 --> 00:13:40,614 And after, the other harmonics are like this. 254 00:13:42,354 --> 00:13:43,787 And so on, okay? 255 00:13:43,856 --> 00:13:46,950 So, the full sound that we can listen to 256 00:13:47,026 --> 00:13:50,655 is a mixture of all these harmonics. 257 00:13:50,729 --> 00:13:53,994 Freeman: But the number of harmonics you can hear 258 00:13:54,066 --> 00:13:56,296 depends on the size of the piano. 259 00:13:56,368 --> 00:13:59,565 The size of any musical instrument is finite. 260 00:13:59,638 --> 00:14:03,938 And a string, for instance, cannot vibrate on wavelengths 261 00:14:04,009 --> 00:14:06,443 larger than the size of the string. 262 00:14:06,512 --> 00:14:08,946 So, maybe, if we observe that the Universe 263 00:14:09,014 --> 00:14:11,676 didn't vibrate on very long wavelengths, 264 00:14:11,750 --> 00:14:15,743 maybe the explanation is that space has a finite size. 265 00:14:15,821 --> 00:14:18,619 Freeman: When Jean-Pierre analyzed the ripples 266 00:14:18,691 --> 00:14:20,852 in the Cosmic Microwave Background, 267 00:14:20,926 --> 00:14:24,487 he found that the longest wavelength ripples 268 00:14:24,563 --> 00:14:27,054 were, indeed, missing. 269 00:14:27,132 --> 00:14:30,659 We are surprised because there was missing wavelengths, 270 00:14:30,736 --> 00:14:33,466 missing fluctuation, missing low tones - 271 00:14:33,539 --> 00:14:35,564 you know, like low notes. 272 00:14:35,641 --> 00:14:38,633 Low like this, okay? 273 00:14:38,711 --> 00:14:41,339 They are missing from the cosmic squall. 274 00:14:44,083 --> 00:14:46,244 Freeman: Jean-Pierre's passion for music 275 00:14:46,318 --> 00:14:48,309 gave him a profound cosmic insight - 276 00:14:48,387 --> 00:14:53,120 that the Universe appears to be finite. 277 00:14:53,192 --> 00:14:56,127 But what shape could it be? 278 00:14:56,195 --> 00:14:58,322 Jean-Pierre spends months 279 00:14:58,397 --> 00:15:02,731 carefully testing different shapes for his finite Universe, 280 00:15:02,801 --> 00:15:04,666 trying to make it fit the vibrations 281 00:15:04,737 --> 00:15:06,534 of the Cosmic Microwave Background 282 00:15:06,605 --> 00:15:08,163 as closely as possible, 283 00:15:08,240 --> 00:15:12,108 until, finally, he finds the perfect fit... 284 00:15:15,748 --> 00:15:19,548 ...a 12-sided dodecahedron... 285 00:15:19,618 --> 00:15:21,279 A soccer ball. 286 00:15:25,391 --> 00:15:28,519 Here in my hands here are two different kinds of dodechahedra. 287 00:15:28,594 --> 00:15:32,325 The first one is just an ordinary dodecahedron, 288 00:15:32,398 --> 00:15:34,764 namely 12 pentagonal faces 289 00:15:34,833 --> 00:15:36,664 arranged in a symmetrical manner. 290 00:15:36,735 --> 00:15:39,067 This is a figure known since antiquity. 291 00:15:39,138 --> 00:15:42,471 You see that the pentagons are flat, okay? 292 00:15:42,541 --> 00:15:46,637 Here, you have a different styling of the sphere. 293 00:15:46,712 --> 00:15:49,476 You see that the pentagons are curved, okay? 294 00:15:49,548 --> 00:15:53,109 So this is called the circle dodecahedron. 295 00:15:53,185 --> 00:15:56,154 Freeman: If Jean-Pierre is right, the shape of the Universe 296 00:15:56,221 --> 00:16:00,214 is a lot more complex than a six-sided "Asteroids" game cube. 297 00:16:00,292 --> 00:16:03,193 The Universe has 12 sides, 298 00:16:03,262 --> 00:16:05,287 and leaving one face leads you 299 00:16:05,364 --> 00:16:08,458 to a matching pentagon on the opposite side, 300 00:16:08,534 --> 00:16:10,331 but with a twist. 301 00:16:10,402 --> 00:16:14,361 This edge is exactly the same as the opposite edge. 302 00:16:14,440 --> 00:16:17,204 So, as soon as you get to this point, 303 00:16:17,276 --> 00:16:20,336 you re-enter your space on the opposite side, 304 00:16:20,412 --> 00:16:24,075 and, in addition, you have to turn by 36 degrees. 305 00:16:24,149 --> 00:16:26,617 Freeman: If the Universe were a dodecahedron 306 00:16:26,685 --> 00:16:28,710 only slightly bigger than Earth, 307 00:16:28,787 --> 00:16:31,585 light would zip around it in minutes, 308 00:16:31,657 --> 00:16:34,717 and you would see twisted copies of Earth 309 00:16:34,793 --> 00:16:37,421 in a dozen different directions in the sky. 310 00:16:37,496 --> 00:16:40,659 But if the edges of Jean-Pierre's dodecahedron 311 00:16:40,733 --> 00:16:42,701 are billions of light-years apart, 312 00:16:42,768 --> 00:16:45,032 the distant and faint reflections on them 313 00:16:45,104 --> 00:16:49,097 could have escaped the notice of the most careful astronomers. 314 00:16:49,174 --> 00:16:50,869 And if the edges lie further 315 00:16:50,943 --> 00:16:53,537 than 13.7 billion light-years from Earth, 316 00:16:53,612 --> 00:16:56,046 we would never be able to see them 317 00:16:56,115 --> 00:16:58,310 because our view would be blocked 318 00:16:58,384 --> 00:17:02,582 by the hot soup of the Cosmic Microwave Background. 319 00:17:02,654 --> 00:17:05,714 As soon as Jean-Pierre announced his results, 320 00:17:05,791 --> 00:17:08,692 Neil Cornish begins looking for signs 321 00:17:08,761 --> 00:17:11,286 of his colossal soccer ball. 322 00:17:11,363 --> 00:17:12,660 He's a key scientist 323 00:17:12,731 --> 00:17:15,996 on a NASA spacecraft called WMAP, 324 00:17:16,068 --> 00:17:18,127 which spent five years photographing 325 00:17:18,203 --> 00:17:23,766 the Cosmic Microwave Background in unprecedented detail. 326 00:17:23,842 --> 00:17:26,436 So, here's a possible model of the Universe 327 00:17:26,512 --> 00:17:27,945 based on a dodecahedron. 328 00:17:28,013 --> 00:17:30,948 Inside, we have a balloon 329 00:17:31,016 --> 00:17:33,211 representing the visible Universe, 330 00:17:33,285 --> 00:17:35,048 how far we can see. 331 00:17:35,120 --> 00:17:36,382 And if it was like this, 332 00:17:36,455 --> 00:17:39,049 where the balloon is much smaller than the space, 333 00:17:39,124 --> 00:17:41,649 there would be no signs that we're living in a finite Universe. 334 00:17:45,064 --> 00:17:48,625 But if the visible Universe was so large 335 00:17:48,700 --> 00:17:52,830 that it actually touched onto the edges of the dodecahedron, 336 00:17:52,905 --> 00:17:56,807 then light would actually be able to travel, 337 00:17:56,875 --> 00:17:58,137 wrap right around the Universe. 338 00:17:58,210 --> 00:18:00,906 So now we would have these matching circles 339 00:18:00,979 --> 00:18:02,970 on the microwave sky 340 00:18:03,048 --> 00:18:08,247 where these two spheres intersect to form a circle. 341 00:18:08,320 --> 00:18:11,221 A circle here matching the circle down here. 342 00:18:15,227 --> 00:18:16,717 Now, we have looked 343 00:18:16,795 --> 00:18:19,787 at the Microwave Background data from the WMAP satellite, 344 00:18:19,865 --> 00:18:23,232 and we haven't seen this pattern of matching circles. 345 00:18:25,604 --> 00:18:27,299 Freeman: But Jean-Pierre Luminet 346 00:18:27,372 --> 00:18:29,704 is not ready to give up his soccer-ball universe. 347 00:18:33,345 --> 00:18:35,370 His ideas have triggered a scientific battle 348 00:18:35,447 --> 00:18:40,043 that spans continents and years of meticulous work. 349 00:18:40,119 --> 00:18:44,146 At stake is nothing less than the truth about where we live, 350 00:18:44,223 --> 00:18:45,850 where we came from, 351 00:18:45,924 --> 00:18:49,155 and whether our Universe is alone. 352 00:18:53,499 --> 00:18:55,160 Einstein said, 353 00:18:55,234 --> 00:19:01,366 "Only two things are infinite - the Universe and human folly." 354 00:19:01,440 --> 00:19:06,070 But he admitted he couldn't be sure about the Universe. 355 00:19:06,145 --> 00:19:10,241 In fact, we are now faced with tantalizing hints 356 00:19:10,315 --> 00:19:14,183 that our Universe may not stretch on forever, 357 00:19:14,253 --> 00:19:16,448 that there is a point out there 358 00:19:16,522 --> 00:19:21,016 where the Universe as we know it does not exist. 359 00:19:21,093 --> 00:19:24,688 It's an almost frightening thought. 360 00:19:24,763 --> 00:19:27,459 But before we try to grasp 361 00:19:27,533 --> 00:19:30,991 just what might lay beyond that final boundary, 362 00:19:31,069 --> 00:19:33,503 we need proof. 363 00:19:33,572 --> 00:19:36,370 Glenn Starkman is a Canadian physicist 364 00:19:36,441 --> 00:19:39,968 at Case Western University in Cleveland. 365 00:19:40,045 --> 00:19:42,377 He's taken data analysis to new heights 366 00:19:42,447 --> 00:19:44,915 in search of that proof. 367 00:19:44,983 --> 00:19:47,918 Call him an information junky. 368 00:19:47,986 --> 00:19:50,284 The joke about Canadians is that you go to an airport 369 00:19:50,355 --> 00:19:52,084 and you put up a sign - 370 00:19:52,157 --> 00:19:53,681 "Free sex to the right" 371 00:19:53,759 --> 00:19:56,023 and "Free information on sex to the left" - 372 00:19:56,094 --> 00:19:58,460 and the Canadians are all the ones that go to the left. 373 00:19:58,530 --> 00:19:59,963 I hope I'm not that boring. 374 00:20:00,032 --> 00:20:01,659 Freeman: Glenn had been poring 375 00:20:01,733 --> 00:20:05,430 over Cosmic Microwave Background data from the WMAP probe 376 00:20:05,504 --> 00:20:07,404 for most of the past seven years. 377 00:20:07,472 --> 00:20:09,531 Along with Neil Cornish, 378 00:20:09,608 --> 00:20:12,907 he's been trying to test Jean-Pierre Luminet's prediction 379 00:20:12,978 --> 00:20:17,244 that the shape of space is like a 12-sided soccer ball. 380 00:20:17,316 --> 00:20:19,648 I would have been really happy to find the pattern of circles 381 00:20:19,718 --> 00:20:22,346 that the dodecahedron told us would be there 382 00:20:22,421 --> 00:20:24,013 if the dodecahedron was small, 383 00:20:24,089 --> 00:20:25,647 and we looked for and we didn't find. 384 00:20:25,724 --> 00:20:28,818 Freeman: But all of their tests assumed 385 00:20:28,894 --> 00:20:31,226 that the edges of the soccer-ball universe 386 00:20:31,296 --> 00:20:35,198 are closer than the Microwave Background that blocks our view. 387 00:20:35,267 --> 00:20:37,667 Now Glenn believes he's found a way 388 00:20:37,736 --> 00:20:40,136 to detect the edge of the Universe, 389 00:20:40,205 --> 00:20:45,040 even if it lurks beyond the area we can see. 390 00:20:45,110 --> 00:20:46,475 What you have to understand 391 00:20:46,545 --> 00:20:48,775 is what is this actual pattern of hot and cold spots 392 00:20:48,847 --> 00:20:50,246 that we're seeing on the sphere. 393 00:20:50,315 --> 00:20:52,476 And what it really is is sound waves 394 00:20:52,551 --> 00:20:56,214 that were traveling through the Universe when it was very young. 395 00:20:56,288 --> 00:20:58,916 So you can imagine it like stretching the top of a drum. 396 00:20:58,991 --> 00:21:00,686 At the same time that as it was stretching, 397 00:21:00,759 --> 00:21:02,693 it was actually making the drum vibrate a little. 398 00:21:02,761 --> 00:21:06,754 Freeman: Different-shaped universes, like different-shaped drums, 399 00:21:06,832 --> 00:21:09,323 should leave different patterns of vibrations 400 00:21:09,401 --> 00:21:11,062 on the early Universe. 401 00:21:12,771 --> 00:21:15,137 So, what we're gonna do is we're gonna look at 402 00:21:15,207 --> 00:21:17,641 some different-shaped and different-sized drums, 403 00:21:17,709 --> 00:21:21,145 and what we have over here is a spectrum analyzer. 404 00:21:21,213 --> 00:21:25,172 And Tom has set things up so that when we make some sound, 405 00:21:25,250 --> 00:21:27,480 we're going to get some traces on this computer screen. 406 00:21:27,552 --> 00:21:31,010 So let's start with our nice, round, little drum. 407 00:21:35,661 --> 00:21:38,289 Now let's go with our heart-shaped drum. 408 00:21:41,133 --> 00:21:43,658 It certainly sounded a little bit different. 409 00:21:46,004 --> 00:21:49,201 Finally, we have a star-shaped drum. 410 00:21:55,314 --> 00:21:59,410 When we superimpose the patterns of those three small drums, 411 00:21:59,484 --> 00:22:01,918 we'll see that they're not quite exactly the same. 412 00:22:01,987 --> 00:22:03,454 They have different patterns 413 00:22:03,522 --> 00:22:05,422 and so we can tell the difference 414 00:22:05,490 --> 00:22:07,458 between one small drum and another. 415 00:22:07,526 --> 00:22:09,721 In the same way, what we're planning to do 416 00:22:09,795 --> 00:22:11,786 is use a spectrum analyzer 417 00:22:11,863 --> 00:22:15,162 to look at the different sounds that the Universe made 418 00:22:15,233 --> 00:22:18,566 and to tell what the shape of the Universe is. 419 00:22:18,637 --> 00:22:22,596 Freeman: Glenn's analysis involves such complex mathematics 420 00:22:22,674 --> 00:22:26,872 that he imagines it will take years to find the answer. 421 00:22:26,945 --> 00:22:28,435 I will be incredibly excited 422 00:22:28,513 --> 00:22:31,744 if we turn out to find Jean-Pierre's dodechahedra. 423 00:22:31,817 --> 00:22:33,910 It will be like discovering that the Earth is round 424 00:22:33,985 --> 00:22:35,247 rather than flat. 425 00:22:37,189 --> 00:22:39,919 Freeman: But this scientist is not waiting for data 426 00:22:39,991 --> 00:22:43,119 to answer this monumental question. 427 00:22:43,195 --> 00:22:46,392 Andy Albrecht, a theoretical physicist at U.C. Davis, 428 00:22:46,465 --> 00:22:49,195 is sure the Universe is finite. 429 00:22:49,267 --> 00:22:52,964 He even thinks he can calculate its size. 430 00:22:53,038 --> 00:22:56,804 Andy studies the very first moments after the Big Bang, 431 00:22:56,875 --> 00:22:58,672 when space was nothing more 432 00:22:58,744 --> 00:23:01,838 than a seething, chaotic ball of energy. 433 00:23:01,913 --> 00:23:05,940 Suddenly, a process called inflation takes hold. 434 00:23:06,017 --> 00:23:08,850 It balloons up the Universe at an incredible rate, 435 00:23:08,920 --> 00:23:12,185 doubling its size 100,000 times. 436 00:23:12,257 --> 00:23:14,020 A fraction of a second later, 437 00:23:14,092 --> 00:23:17,960 all space and matter is smoothly spread out. 438 00:23:18,029 --> 00:23:20,293 Most scientists believe 439 00:23:20,365 --> 00:23:23,596 inflation is still happening today. 440 00:23:23,668 --> 00:23:26,136 The going way of thinking about inflation 441 00:23:26,204 --> 00:23:29,173 is that it gives us a truly infinite Universe. 442 00:23:29,241 --> 00:23:32,301 The inflation itself never ends. 443 00:23:32,377 --> 00:23:35,676 The more I thought about what that infinity might really mean, 444 00:23:35,747 --> 00:23:40,184 the more I realized it probably didn't make sense. 445 00:23:40,252 --> 00:23:44,211 Freeman: So, Andy began working on a new theory of inflation, 446 00:23:44,289 --> 00:23:46,086 without infinities. 447 00:23:46,158 --> 00:23:48,490 It's dizzying mathematics, 448 00:23:48,560 --> 00:23:50,687 dealing with the laws of physics 449 00:23:50,762 --> 00:23:53,060 before the Universe as we know it existed. 450 00:23:53,131 --> 00:23:57,830 But at its core, it all boils down to bubbles. 451 00:23:57,903 --> 00:24:01,202 A random process starts the formation 452 00:24:01,273 --> 00:24:03,741 of the bubble that is our Universe. 453 00:24:03,809 --> 00:24:07,643 I will be the random process and blow the bubble. 454 00:24:15,153 --> 00:24:17,212 Freeman: The traditional view of inflation 455 00:24:17,289 --> 00:24:20,520 imagines this bubble inflates forever. 456 00:24:20,592 --> 00:24:23,686 But Andy now takes the lessons he learned in kindergarten 457 00:24:23,762 --> 00:24:25,593 as a serious insight. 458 00:24:25,664 --> 00:24:30,226 A bubble can only grow so big before it pops. 459 00:24:30,302 --> 00:24:33,897 Andy believes inflation must stop 460 00:24:33,972 --> 00:24:37,203 when space gets to a certain maximum size, 461 00:24:37,275 --> 00:24:40,767 and his pioneering theory predicts that size. 462 00:24:40,846 --> 00:24:44,441 The Universe is actually just about 20% bigger 463 00:24:44,516 --> 00:24:46,541 than what we see around us today. 464 00:24:46,618 --> 00:24:50,418 When I first started trying out those ideas, 465 00:24:50,489 --> 00:24:53,788 it was really difficult to go all the way from infinity 466 00:24:53,859 --> 00:24:56,327 to such a small thing, just a little bit larger - 467 00:24:56,394 --> 00:25:00,592 just 20% larger than what we see around us today. 468 00:25:00,665 --> 00:25:02,599 I actually felt claustrophobic. 469 00:25:02,667 --> 00:25:05,898 Freeman: But if Andy's new theory is right 470 00:25:05,971 --> 00:25:08,405 and inflation does not go on forever, 471 00:25:08,473 --> 00:25:11,306 our Universe could look something like this - 472 00:25:11,376 --> 00:25:15,870 a large bubble surrounded by a cluster of smaller ones. 473 00:25:18,149 --> 00:25:21,016 Most cosmologists think inflation 474 00:25:21,086 --> 00:25:24,385 is the best explanation for the even spread of galaxies 475 00:25:24,456 --> 00:25:26,617 across our visible Universe. 476 00:25:26,691 --> 00:25:29,387 But far out in space, 477 00:25:29,461 --> 00:25:34,626 there may be regions where inflation never took place. 478 00:25:34,699 --> 00:25:37,259 Find those, and you could be the first 479 00:25:37,335 --> 00:25:41,362 to find evidence of the edge of the Universe. 480 00:25:46,344 --> 00:25:50,747 The eternal dance of light in the night sky - 481 00:25:50,815 --> 00:25:54,911 it has fascinated humankind for thousands of years, 482 00:25:54,986 --> 00:25:58,149 given birth to gods, myths, 483 00:25:58,223 --> 00:26:01,852 and, finally, to science. 484 00:26:01,927 --> 00:26:04,521 But now there are hints of strange movements 485 00:26:04,596 --> 00:26:06,154 in the heavens. 486 00:26:06,231 --> 00:26:08,722 If they can be verified, 487 00:26:08,800 --> 00:26:10,700 they'll be the first hard evidence 488 00:26:10,769 --> 00:26:14,899 that there is an edge to the Universe. 489 00:26:19,711 --> 00:26:23,078 Sasha Kashlinsky is a NASA astronomer. 490 00:26:23,148 --> 00:26:24,706 He claims to have detected 491 00:26:24,783 --> 00:26:28,150 a pattern of movement in the heavens so bizarre 492 00:26:28,219 --> 00:26:32,280 that it could revolutionize our theory of the Universe, 493 00:26:32,357 --> 00:26:34,882 just as the Big Bang once did. 494 00:26:36,328 --> 00:26:39,695 We're here at Glendale Golf Course 495 00:26:39,764 --> 00:26:42,062 near NASA's Goddard Space Flight Center. 496 00:26:42,133 --> 00:26:45,102 And we came here to simulate the Big Bang. 497 00:26:45,170 --> 00:26:48,139 So let me try and do that. 498 00:26:51,876 --> 00:26:54,003 As you see, the balls, 499 00:26:54,079 --> 00:26:56,946 they just move away from the mutual center. 500 00:26:57,015 --> 00:26:59,745 Freeman: This even spreading-out of galaxies 501 00:26:59,818 --> 00:27:01,911 from a central explosive beginning 502 00:27:01,987 --> 00:27:05,718 is what astronomers see when they look at the night sky. 503 00:27:05,790 --> 00:27:07,917 But Sasha wanted to check more precisely 504 00:27:07,993 --> 00:27:11,588 how fast and in what direction galaxies are moving 505 00:27:11,663 --> 00:27:14,826 to see if there might be any subtle deviations. 506 00:27:14,899 --> 00:27:17,333 He used an effect that can only be seen 507 00:27:17,402 --> 00:27:20,166 when clusters of galaxies are colliding. 508 00:27:20,238 --> 00:27:23,799 The gases around them get heated to millions of degrees. 509 00:27:23,875 --> 00:27:27,242 When light from the Cosmic Microwave Background 510 00:27:27,312 --> 00:27:29,246 passes through that hot gas, 511 00:27:29,314 --> 00:27:31,942 it gets subtly altered. 512 00:27:32,017 --> 00:27:35,418 How much it changes depends on exactly how fast 513 00:27:35,487 --> 00:27:39,890 the gas and the galaxies it surrounds are moving. 514 00:27:39,958 --> 00:27:42,051 But the change is tiny 515 00:27:42,127 --> 00:27:45,324 and almost completely buried in background noise. 516 00:27:45,397 --> 00:27:50,460 For each individual cluster, this is a very tiny amount, 517 00:27:50,535 --> 00:27:53,732 and it gets drowned by the noise. 518 00:27:53,805 --> 00:27:58,139 But if you have many clusters, you can beat down the noise, 519 00:27:58,209 --> 00:28:02,077 but it's exceedingly difficult. 520 00:28:02,147 --> 00:28:04,843 Freeman: Sasha methodically worked his way 521 00:28:04,916 --> 00:28:07,282 through a catalog of galaxy clusters 522 00:28:07,352 --> 00:28:09,684 from an orbiting x-ray telescope, 523 00:28:09,754 --> 00:28:13,019 checked their precise position using ground telescopes, 524 00:28:13,091 --> 00:28:15,116 and then carefully lined them up 525 00:28:15,193 --> 00:28:18,128 with the Cosmic Microwave Background. 526 00:28:18,196 --> 00:28:21,962 Oh, we were quite shocked 527 00:28:22,033 --> 00:28:24,934 when we saw these results at first. 528 00:28:25,003 --> 00:28:28,268 In fact, so much that we didn't know what to do with it. 529 00:28:28,339 --> 00:28:30,068 We kept checking and checking. 530 00:28:30,141 --> 00:28:32,336 We sat on the data for a year-plus, 531 00:28:32,410 --> 00:28:33,968 just checking everything, 532 00:28:34,045 --> 00:28:36,673 because it just didn't make sense to us. 533 00:28:36,748 --> 00:28:41,082 Freeman: What Sasha's data showed was almost unbelievable. 534 00:28:41,152 --> 00:28:42,642 All the galaxy clusters, 535 00:28:42,721 --> 00:28:45,121 no matter where they were in the sky, 536 00:28:45,190 --> 00:28:49,422 were all veering off to one side of the Universe. 537 00:28:49,494 --> 00:28:51,587 It was as if they were being pulled 538 00:28:51,663 --> 00:28:56,123 towards a mysterious attractor beyond the visible edge. 539 00:28:56,201 --> 00:29:00,433 He called it "Dark Flow." 540 00:29:00,505 --> 00:29:02,200 We called it "Dark Flow" because 541 00:29:02,273 --> 00:29:05,071 the observed distribution of matter in the Universe 542 00:29:05,143 --> 00:29:08,476 cannot account for this motion. 543 00:29:08,546 --> 00:29:11,071 Freeman: But if nothing Sasha could see 544 00:29:11,149 --> 00:29:13,515 was pulling the galaxies to one side, 545 00:29:13,585 --> 00:29:16,486 what could be responsible for the effect? 546 00:29:16,554 --> 00:29:20,752 The answer could be the edge of the Universe. 547 00:29:20,825 --> 00:29:24,955 Kashlinsky: If you live in this part of the world, 548 00:29:25,029 --> 00:29:28,362 then, at first, you would imagine that the entire world 549 00:29:28,433 --> 00:29:30,697 is as flat as what you see locally. 550 00:29:30,769 --> 00:29:34,330 But if you were to look sufficiently far away, 551 00:29:34,405 --> 00:29:35,736 you may discover that the world 552 00:29:35,807 --> 00:29:37,832 is very different from what you see locally. 553 00:29:37,909 --> 00:29:41,436 Freeman: Cosmologists, ever since Einstein, 554 00:29:41,513 --> 00:29:44,346 have thought of the Universe being like a flat putting green 555 00:29:44,415 --> 00:29:46,610 that extends on forever. 556 00:29:46,684 --> 00:29:50,381 But Dark Flow could be hinting that our Universe 557 00:29:50,455 --> 00:29:53,288 is a finite space... 558 00:29:53,358 --> 00:29:56,418 surrounded by stranger terrain. 559 00:29:56,494 --> 00:29:59,930 So, this was Big Bang on a flat surface. 560 00:29:59,998 --> 00:30:03,627 So, now let's go to a different part of the world. 561 00:30:11,409 --> 00:30:14,105 The balls did, indeed, disperse, 562 00:30:14,179 --> 00:30:18,309 but, in addition, they also have another velocity, 563 00:30:18,383 --> 00:30:21,318 which is associated with the tilt of this surface. 564 00:30:21,386 --> 00:30:24,116 They move collectively and systematically 565 00:30:24,189 --> 00:30:27,022 from the higher ground to the lower ground. 566 00:30:27,091 --> 00:30:31,084 Freeman: Sasha's discovery of a collective, systematic movement 567 00:30:31,162 --> 00:30:34,495 of galaxies to one side of the cosmos 568 00:30:34,566 --> 00:30:37,330 has shaken the field of cosmology. 569 00:30:37,402 --> 00:30:40,394 Some scientists refuse to believe it. 570 00:30:43,474 --> 00:30:48,878 But for this woman, Dark Flow was entirely expected, 571 00:30:48,947 --> 00:30:51,006 and her ideas about the Universe 572 00:30:51,082 --> 00:30:54,142 are even more mind-bending than Sasha's. 573 00:30:54,219 --> 00:30:56,084 She believes she's found evidence 574 00:30:56,154 --> 00:31:00,784 that another Universe is reaching out and touching ours. 575 00:31:08,933 --> 00:31:13,996 Scientists have discovered a mysterious Dark Flow of galaxies 576 00:31:14,072 --> 00:31:18,099 all veering off to one side of our Universe. 577 00:31:18,176 --> 00:31:22,408 It could be a sign that way out beyond that furthest star 578 00:31:22,480 --> 00:31:24,744 lurks a portion of the cosmos 579 00:31:24,816 --> 00:31:28,775 vastly different than the Universe we know. 580 00:31:28,853 --> 00:31:32,516 But there's an even more shocking possibility. 581 00:31:32,590 --> 00:31:34,888 Dark Flow could be evidence 582 00:31:34,959 --> 00:31:39,191 of another universe reaching out to us. 583 00:31:39,264 --> 00:31:41,255 That's what theoretical physicist 584 00:31:41,332 --> 00:31:43,357 Laura Mersini-Houghton thinks. 585 00:31:43,434 --> 00:31:46,597 The seed of this idea was planted many years ago 586 00:31:46,671 --> 00:31:50,402 when she realized she had a problem with the Universe - 587 00:31:50,475 --> 00:31:52,443 a pretty big problem. 588 00:31:52,510 --> 00:31:54,910 According to her calculations, 589 00:31:54,979 --> 00:31:58,745 the Universe should not exist. 590 00:31:58,816 --> 00:32:00,647 The chances to start the Universe 591 00:32:00,718 --> 00:32:03,118 with the high-energy Big Bang 592 00:32:03,187 --> 00:32:08,489 are one in 10 with another 10 zeros behind it 593 00:32:08,559 --> 00:32:11,426 and another 123 zeros behind it. 594 00:32:11,496 --> 00:32:14,727 So, pretty much, zero. 595 00:32:14,799 --> 00:32:19,395 So whenever in science we end up with an answer 596 00:32:19,470 --> 00:32:22,701 that "This seems very unlikely. 597 00:32:22,774 --> 00:32:25,402 This event is not generic," 598 00:32:25,476 --> 00:32:27,876 then it usually indicates 599 00:32:27,946 --> 00:32:31,905 that we have blundered in something very basic. 600 00:32:31,983 --> 00:32:35,919 Freeman: But Laura had an idea of how to stop the Big Bang 601 00:32:35,987 --> 00:32:38,421 from being such an unlikely event. 602 00:32:38,489 --> 00:32:42,448 You might call it a gambler's hunch. 603 00:32:44,195 --> 00:32:45,594 If you're playing a slot machine 604 00:32:45,663 --> 00:32:47,426 where the odds of hitting the jackpot 605 00:32:47,498 --> 00:32:49,432 are 1 million to one, 606 00:32:49,500 --> 00:32:52,628 you could play all day and never strike it rich. 607 00:32:52,704 --> 00:32:54,638 But if all 6 billion people on Earth 608 00:32:54,706 --> 00:32:57,231 each played their own slot machine, 609 00:32:57,308 --> 00:33:00,300 someone somewhere is going to get rich 610 00:33:00,378 --> 00:33:02,539 about once every few seconds. 611 00:33:05,183 --> 00:33:08,482 Laura realized that one branch of theoretical physics 612 00:33:08,553 --> 00:33:12,455 offered a way to turn the Big Bang into a sure bet. 613 00:33:12,523 --> 00:33:14,821 It was string theory. 614 00:33:14,892 --> 00:33:17,258 This view of reality suggests 615 00:33:17,328 --> 00:33:21,059 that alongside the normal three dimensions of space, 616 00:33:21,132 --> 00:33:24,590 there are another seven hidden dimensions 617 00:33:24,669 --> 00:33:28,366 wrapped up so tightly, we cannot see them. 618 00:33:28,439 --> 00:33:30,339 Mersini-Houghton: You start wrapping up 619 00:33:30,408 --> 00:33:32,774 those extra dimensions, the extra seven dimensions. 620 00:33:32,844 --> 00:33:36,746 There are so many ways of doing that process. 621 00:33:36,814 --> 00:33:39,339 String theorists ended up 622 00:33:39,417 --> 00:33:42,648 with not just one 3-dimensional world, 623 00:33:42,720 --> 00:33:46,679 but with many, many possible 3-dimensional worlds. 624 00:33:46,758 --> 00:33:50,353 Freeman: In fact, string theorists realized 625 00:33:50,428 --> 00:33:53,420 there were 10 to the power of 500 possible ways 626 00:33:53,498 --> 00:33:56,228 to arrange these dimensions. 627 00:33:56,300 --> 00:34:00,100 That's a one with 500 zeros behind it, 628 00:34:00,171 --> 00:34:03,038 a number countless times bigger 629 00:34:03,107 --> 00:34:06,008 than the odds against our Big Bang. 630 00:34:06,077 --> 00:34:09,046 The only way we can ask the question 631 00:34:09,113 --> 00:34:11,343 about the origins of the Universe 632 00:34:11,416 --> 00:34:14,010 is if we have a multiverse structure 633 00:34:14,085 --> 00:34:15,950 from which our Universe is born, 634 00:34:16,020 --> 00:34:20,889 a landscape of many possible places in this multiverse 635 00:34:20,958 --> 00:34:22,892 where the Universe can start from. 636 00:34:22,960 --> 00:34:27,226 Freeman: If each of these balls of wrapped-up dimensions 637 00:34:27,298 --> 00:34:30,756 is an energy site where a Universe could start, 638 00:34:30,835 --> 00:34:33,998 then the odds of a Big Bang happening in one of them 639 00:34:34,072 --> 00:34:36,472 is no longer an enormous long shot. 640 00:34:36,541 --> 00:34:39,305 In fact, the odds are good enough 641 00:34:39,377 --> 00:34:42,175 that Laura's willing to bet this landscape 642 00:34:42,246 --> 00:34:47,411 should contain many Big Bangs and many universes. 643 00:34:47,485 --> 00:34:49,385 You can think of this multiverse landscape 644 00:34:49,454 --> 00:34:52,321 as the biggest hotel you can imagine, 645 00:34:52,390 --> 00:34:55,587 a hotel with 10 to the power of 500 rooms, 646 00:34:55,660 --> 00:35:00,222 each one waiting for a guest to check in. 647 00:35:00,298 --> 00:35:02,232 Mersini-Houghton: Every room would represent 648 00:35:02,300 --> 00:35:05,292 an energy site of that landscape. 649 00:35:05,369 --> 00:35:07,564 There is an infinite number of people 650 00:35:07,638 --> 00:35:10,573 that can try to check in into these hotel rooms. 651 00:35:10,641 --> 00:35:13,474 I try to go into a room, 652 00:35:13,544 --> 00:35:16,707 and I discover that energy site is taken. 653 00:35:16,781 --> 00:35:18,578 Someone else is there. 654 00:35:18,649 --> 00:35:23,450 Once a universe is born in that energy site, 655 00:35:23,521 --> 00:35:25,614 first, that energy site 656 00:35:25,690 --> 00:35:27,817 cannot be shared with another universe. 657 00:35:27,892 --> 00:35:30,520 So I try to go to the next room. 658 00:35:34,565 --> 00:35:38,092 Until I find an empty room. 659 00:35:38,169 --> 00:35:42,833 That room is really boiling hot, so it contains a lot of energy. 660 00:35:42,907 --> 00:35:46,900 Once I am in the room, I cannot get out of it anymore. 661 00:35:46,978 --> 00:35:50,914 The door is locked. That's how the Universe is born. 662 00:35:58,156 --> 00:36:01,557 Freeman: But if our Universe is like a hotel room, 663 00:36:01,626 --> 00:36:04,720 shouldn't we be able to detect the presence of guests 664 00:36:04,795 --> 00:36:06,888 in the room next door? 665 00:36:06,964 --> 00:36:09,364 That earth-shattering evidence 666 00:36:09,433 --> 00:36:13,563 could look as subtle as this small blue patch. 667 00:36:13,638 --> 00:36:17,574 In 2007, data from the WMAP spacecraft 668 00:36:17,642 --> 00:36:20,839 confirmed the presence of a strange, cold spot 669 00:36:20,912 --> 00:36:23,278 in the Cosmic Microwave Background. 670 00:36:27,051 --> 00:36:29,042 If I have an empty region of space, 671 00:36:29,120 --> 00:36:31,554 that would show as a cold temperature region. 672 00:36:31,622 --> 00:36:33,715 In the case of the cold spot, 673 00:36:33,791 --> 00:36:36,487 the only way such a part of the sky 674 00:36:36,561 --> 00:36:38,961 could just be completely, entirely empty, 675 00:36:39,030 --> 00:36:42,625 that kind of bizarre behavior of the Universe 676 00:36:42,700 --> 00:36:46,727 can occur only if there is some other force at work. 677 00:36:46,804 --> 00:36:49,739 Laura believes the cold spot 678 00:36:49,807 --> 00:36:53,140 is evidence of another universe right next to ours, 679 00:36:53,211 --> 00:36:57,511 its enormous mass pulling on matter at the edge of our world. 680 00:37:00,718 --> 00:37:04,415 Mersini-Houghton: If there are some very massive objects in the next room - 681 00:37:04,488 --> 00:37:07,548 in other words, in the neighboring universe - 682 00:37:07,625 --> 00:37:11,584 then I should be able to feel that gravitational pull, 683 00:37:11,662 --> 00:37:13,596 although I cannot directly see it. 684 00:37:13,664 --> 00:37:15,461 Freeman: But for a theory as radical 685 00:37:15,533 --> 00:37:18,127 as the existence of another universe, 686 00:37:18,202 --> 00:37:20,670 the cold spot alone is not enough. 687 00:37:20,738 --> 00:37:25,038 Laura needs more evidence. 688 00:37:26,110 --> 00:37:28,840 And help is at hand. 689 00:37:28,913 --> 00:37:31,677 Two scientists are about to join forces 690 00:37:31,749 --> 00:37:34,741 in a remarkable endeavor 691 00:37:34,819 --> 00:37:37,845 to find the size and shape of our Universe 692 00:37:37,922 --> 00:37:41,085 and the universe next door. 693 00:37:46,330 --> 00:37:49,458 Is the Universe infinite? 694 00:37:49,533 --> 00:37:51,467 Or does it have an edge? 695 00:37:53,337 --> 00:37:55,737 Or is our Universe just one member 696 00:37:55,806 --> 00:37:57,831 of a cosmic family of universes, 697 00:37:57,908 --> 00:38:02,811 spread across a strange and uncharted landscape? 698 00:38:02,880 --> 00:38:04,575 Just a few years ago, 699 00:38:04,649 --> 00:38:08,949 even asking these questions was unthinkable. 700 00:38:09,020 --> 00:38:13,650 Now we're close to finding the answer. 701 00:38:13,724 --> 00:38:17,319 Sasha Kashlinsky is convinced 702 00:38:17,395 --> 00:38:21,855 that some mysterious attractor at the edge of our Universe 703 00:38:21,932 --> 00:38:23,991 is pulling on galaxies, 704 00:38:24,068 --> 00:38:28,664 forcing them to move with what he calls "Dark Flow." 705 00:38:28,739 --> 00:38:31,003 His work is still controversial, 706 00:38:31,075 --> 00:38:34,374 and to convince the skeptics, he needs more data. 707 00:38:34,445 --> 00:38:36,936 We hope, in a few years, 708 00:38:37,014 --> 00:38:42,884 to have a catalog of up to 2,000 galaxy clusters in total. 709 00:38:42,953 --> 00:38:46,582 And with the new data, we hope that we'll be able 710 00:38:46,657 --> 00:38:49,421 to measure the flow to much larger scales. 711 00:38:49,493 --> 00:38:53,862 Freeman: But Sasha now has a powerful ally. 712 00:38:53,931 --> 00:38:56,832 1,000 miles away, in Toronto, 713 00:38:56,901 --> 00:38:59,426 Laura Mersini-Houghton was defining her own calculations 714 00:38:59,503 --> 00:39:02,165 about the edge of the Universe 715 00:39:02,239 --> 00:39:05,333 when she got a phone call from her mother. 716 00:39:05,409 --> 00:39:08,606 Mersini-Houghton: And she says to me, "Did you see the news 717 00:39:08,679 --> 00:39:11,614 about something called Dark Flow or another? 718 00:39:11,682 --> 00:39:14,742 There was a NASA person there." 719 00:39:14,819 --> 00:39:17,049 And I said, "No, I haven't." 720 00:39:17,121 --> 00:39:19,089 So I went straight into my computer 721 00:39:19,156 --> 00:39:24,025 and found out that a team at NASA led by Sasha Kashlinsky 722 00:39:24,095 --> 00:39:27,553 had reported they had seen the Dark Flow 723 00:39:27,631 --> 00:39:30,259 of structure in the Universe. 724 00:39:30,334 --> 00:39:33,792 That was exactly in perfect agreement 725 00:39:33,871 --> 00:39:36,601 with the prediction we had made two years ago. 726 00:39:36,674 --> 00:39:39,404 But what made it spookier was that even the numbers, 727 00:39:39,477 --> 00:39:42,605 the speed at which those galaxies were moving 728 00:39:42,680 --> 00:39:44,944 and the direction into which they were moving 729 00:39:45,015 --> 00:39:49,145 were in absolute perfect agreement astronomically 730 00:39:49,220 --> 00:39:51,211 with our predictions. 731 00:39:52,990 --> 00:39:55,788 Freeman: Now Laura and Sasha are both contemplating 732 00:39:55,860 --> 00:39:59,796 just how this exotic landscape outside our Universe 733 00:39:59,864 --> 00:40:01,798 might behave. 734 00:40:01,866 --> 00:40:05,302 Mersini-Houghton: I can think of this board as the landscape, 735 00:40:05,369 --> 00:40:07,030 the energy sites onto which 736 00:40:07,104 --> 00:40:09,334 these wave pockets of the Universe 737 00:40:09,407 --> 00:40:10,897 will eventually settle. 738 00:40:10,975 --> 00:40:13,808 Now, I have to send the wave pockets 739 00:40:13,878 --> 00:40:16,711 through that landscape, through that board 740 00:40:16,781 --> 00:40:18,612 in order to populate it. 741 00:40:20,584 --> 00:40:22,484 Freeman: Think of this marble 742 00:40:22,553 --> 00:40:26,011 as the pulse of energy that triggered our Big Bang. 743 00:40:26,090 --> 00:40:29,457 Soon, another pulse of energy comes along. 744 00:40:29,527 --> 00:40:31,586 It falls into a different dip, 745 00:40:31,662 --> 00:40:34,358 and a neighboring universe is born. 746 00:40:34,432 --> 00:40:38,300 That universe is not a place we can ever go. 747 00:40:38,369 --> 00:40:39,927 Its arrangement of dimensions 748 00:40:40,004 --> 00:40:42,268 will be completely different from ours. 749 00:40:42,339 --> 00:40:47,242 But there is one way we can sense its presence. 750 00:40:47,311 --> 00:40:50,576 If the two universes are close enough together, 751 00:40:50,648 --> 00:40:54,015 their gravitational attraction will pull anything with mass 752 00:40:54,084 --> 00:40:57,144 towards their respective edges. 753 00:40:57,221 --> 00:40:59,553 That's why we see the cold spot 754 00:40:59,623 --> 00:41:02,387 and that's why there's a Dark Flow of galaxies 755 00:41:02,460 --> 00:41:04,894 moving across the cosmos. 756 00:41:04,962 --> 00:41:09,228 This other universe is pulling on ours. 757 00:41:09,300 --> 00:41:12,633 Until about three, four years ago, 758 00:41:12,703 --> 00:41:15,831 we knew nothing of the multiverse. 759 00:41:15,906 --> 00:41:18,033 However, things are changing dramatically 760 00:41:18,108 --> 00:41:19,473 in the last few years. 761 00:41:19,543 --> 00:41:23,502 Technology is helping us find signatures 762 00:41:23,581 --> 00:41:25,549 of the existence of the multiverse. 763 00:41:25,616 --> 00:41:28,414 Freeman: But across the world of cosmology, 764 00:41:28,486 --> 00:41:31,853 the reactions to these scientists' controversial work 765 00:41:31,922 --> 00:41:33,321 is mixed. 766 00:41:33,390 --> 00:41:35,153 If any one of them is right, 767 00:41:35,226 --> 00:41:37,751 the implications would be enormous. 768 00:41:37,828 --> 00:41:42,231 Why do we even care about the size and shape of the Universe? 769 00:41:42,299 --> 00:41:45,063 That part of the story is critical 770 00:41:45,135 --> 00:41:48,002 for our attempts to understand how it all came into being, 771 00:41:48,072 --> 00:41:49,937 why it is the way it is, 772 00:41:50,007 --> 00:41:52,100 and why we see what we see around us. 773 00:41:52,176 --> 00:41:55,612 All these questions have very different answers 774 00:41:55,679 --> 00:41:57,704 if we're looking at the infinite story 775 00:41:57,781 --> 00:41:59,214 or the finite story. 776 00:41:59,283 --> 00:42:01,683 We'd be able to say, "Look, here is the Universe. 777 00:42:01,752 --> 00:42:04,414 This is its shape. And that's where we live." 778 00:42:04,488 --> 00:42:07,048 And that's a revolution in physics - 779 00:42:07,124 --> 00:42:09,354 going outside our Universe, 780 00:42:09,426 --> 00:42:12,020 at least with the power of our imagination. 781 00:42:12,096 --> 00:42:16,465 But then that's what makes human beings special. 782 00:42:16,534 --> 00:42:19,594 Freeman: Every now and again, 783 00:42:19,670 --> 00:42:23,766 our perception of the Universe and our place in it 784 00:42:23,841 --> 00:42:26,241 undergoes a revolution. 785 00:42:26,310 --> 00:42:31,179 We used to think the Earth was the center of all creation. 786 00:42:31,248 --> 00:42:33,546 For the past century, 787 00:42:33,617 --> 00:42:36,142 we've learned to accept that we live 788 00:42:36,220 --> 00:42:39,246 in a nondescript region of a backwater galaxy 789 00:42:39,323 --> 00:42:43,919 in a Universe that is unimaginably vast. 790 00:42:46,530 --> 00:42:49,931 Now it's time for another change of perspective. 791 00:42:52,469 --> 00:42:57,065 Our Universe itself, once assumed to be infinite, 792 00:42:57,141 --> 00:42:59,803 might have to shrink down and take its rightful place 793 00:42:59,877 --> 00:43:03,643 as a humble member of a truly giant multiverse, 794 00:43:03,714 --> 00:43:06,649 a multiverse filled with universes 795 00:43:06,717 --> 00:43:09,811 beyond our wildest imaginations.