1 00:00:04,714 --> 00:00:08,259 NARRATOR: Humans are natural-ham explorers. 2 00:00:08,467 --> 00:00:12,847 We charge into uncharted territory and seek out the unknown. 3 00:00:14,432 --> 00:00:16,475 We've mapped nearly every inch of Mother Earth... 4 00:00:18,477 --> 00:00:20,855 ...and left tracks on the moon. 5 00:00:21,063 --> 00:00:23,441 But to set foot on another planet... 6 00:00:23,649 --> 00:00:25,943 ...to travel beyond our solar system... 7 00:00:26,110 --> 00:00:28,613 ...that is a dream for the future. 8 00:00:33,451 --> 00:00:37,830 A dream that comes to life in the feature film Interstellar. 9 00:00:39,415 --> 00:00:45,213 BRAND: We must think not as individuals but as a species. 10 00:00:45,379 --> 00:00:49,217 We must confront the reality of interstellar travel. 11 00:00:54,222 --> 00:00:59,727 NARRATOR: The film Interstellar deals with the quest for new worlds and the fate of humanity. 12 00:01:00,478 --> 00:01:02,730 Sound like the stuff of science fiction? 13 00:01:03,314 --> 00:01:04,732 Maybe. 14 00:01:04,899 --> 00:01:09,570 But the foundations of this film are rooted in real science... 15 00:01:09,737 --> 00:01:14,325 ...thanks to the involvement of renowned astrophysicist Kip Thorne. 16 00:01:14,492 --> 00:01:18,246 In Interstellar, one of the most important features... 17 00:01:18,412 --> 00:01:22,917 ...is the way that the science is totally embedded in the film. 18 00:01:23,084 --> 00:01:24,877 There are some wild things in here. 19 00:01:26,003 --> 00:01:31,259 NARRATOR: Beyond fantasy and fiction, this is the real science of Interstellar. 20 00:01:39,767 --> 00:01:42,770 Space travel has been a staple of the movies from the very beginning... 21 00:01:42,937 --> 00:01:46,524 ...but the feature film Interstellar has a unique pedigree. 22 00:01:46,691 --> 00:01:49,443 It was inspired in part by the work of Kip Thorne... 23 00:01:51,654 --> 00:01:55,408 ...an authority on astrophysics, gravitational waves... 24 00:01:55,574 --> 00:01:58,327 ...and the warping of space-time. 25 00:01:58,494 --> 00:02:01,539 He's also an executive producer on the film. 26 00:02:01,872 --> 00:02:07,712 In Interstellar, real science was built into the fabric of the film from the outset. 27 00:02:08,212 --> 00:02:13,926 The other major players in this film, they all respected the science... 28 00:02:14,093 --> 00:02:18,014 ...and they worked with me to see that the science was well incorporated. 29 00:02:18,180 --> 00:02:24,645 Can you tell me what the easiest definition of what a singularity is? 30 00:02:24,812 --> 00:02:29,859 Kip and myself meshed well in terms of trying to use current thinking... 31 00:02:30,026 --> 00:02:33,154 ...current scientific understanding to drive the narrative. 32 00:02:33,321 --> 00:02:34,697 The language we use... 33 00:02:34,864 --> 00:02:41,203 ...is it's a place where the curvature of space and time gets infinitely high. 34 00:02:41,370 --> 00:02:42,455 So we're good, okay. 35 00:02:42,621 --> 00:02:46,834 And we just hope that the research we've done and the conversations I'd had with Kip... 36 00:02:47,001 --> 00:02:50,379 ...and that Chris had had with Kip informed the narrative... 37 00:02:50,546 --> 00:02:52,423 ...and that the audience would feel that. 38 00:02:52,590 --> 00:02:55,718 NOLAN: Why simply imagine, fantasize... 39 00:02:55,885 --> 00:02:59,513 ...about things that might happen in space or on an interstellar journey? 40 00:02:59,680 --> 00:03:02,850 Why not actually look at, uh, the real science there? 41 00:03:05,603 --> 00:03:06,979 It's an Indian surveillance drone. 42 00:03:07,146 --> 00:03:09,065 NARRATOR: Interstellar takes place in a future... 43 00:03:09,231 --> 00:03:12,985 ...where living conditions on Earth threaten the survival of humanity. 44 00:03:13,903 --> 00:03:17,031 BRAND: Your daughter's generation will be the last to survive on Earth. 45 00:03:17,198 --> 00:03:20,534 COOPER: Now you need to tell me what your plan is to save the world. 46 00:03:20,701 --> 00:03:23,913 BRAND: We're not meant to save the world, we're meant to leave it. 47 00:03:24,872 --> 00:03:28,501 One of the things that the film explores is, do we belong on Earth... 48 00:03:28,667 --> 00:03:31,796 ...and should we be staying on Earth... 49 00:03:31,962 --> 00:03:35,007 ...and if there is anything else out there, should we be exploring that? 50 00:03:35,341 --> 00:03:36,634 Here we go. 51 00:03:36,801 --> 00:03:39,428 NARRATOR: In the film, the crew seeks a new place to call home. 52 00:03:39,595 --> 00:03:41,263 A planet that can sustain life. 53 00:03:42,098 --> 00:03:43,224 Human life. 54 00:03:43,391 --> 00:03:44,642 - I'm not gonna make it! - Yes, you are. 55 00:03:44,809 --> 00:03:47,770 It's an exciting concept that there may be other worlds out there. 56 00:03:48,437 --> 00:03:51,148 Well, what are those worlds and what could they be... 57 00:03:51,315 --> 00:03:53,234 ...and is there a place for us out there? 58 00:03:53,734 --> 00:03:55,319 NARRATOR: The search for another Earth... 59 00:03:55,486 --> 00:03:58,280 ...sounds like a job for the explorers of tomorrow... 60 00:03:58,781 --> 00:04:01,575 ...but it's happening right now. 61 00:04:05,037 --> 00:04:09,250 Astrophysicist Natalie Batalha is a passionate planet hunter. 62 00:04:09,417 --> 00:04:13,170 BATALHA: I think the only way that we're going to really understand our place in the galaxy... 63 00:04:13,337 --> 00:04:18,926 ...is by looking at this broad picture and understanding the diversity of all planets. 64 00:04:19,093 --> 00:04:21,137 Twenty or 30 years ago, we didn't know... 65 00:04:21,303 --> 00:04:25,724 ...of any other planets orbiting normal stars like our own sun. 66 00:04:26,434 --> 00:04:29,311 NARRATOR: Natalie has helped rewrite that story as mission scientist... 67 00:04:29,478 --> 00:04:31,397 ...for NASA's Kepler space telescope. 68 00:04:31,564 --> 00:04:33,858 BATALHA: Kepler's objective is very simple. 69 00:04:34,024 --> 00:04:37,319 It's to determine the fraction of stars in our galaxy... 70 00:04:37,486 --> 00:04:41,282 ...that harbor potentially habitable Earth-size planets. 71 00:04:41,449 --> 00:04:43,742 NARRATOR: And what makes a planet potentially habitable? 72 00:04:43,909 --> 00:04:46,954 The one ingredient that we think is common to all life forms... 73 00:04:47,121 --> 00:04:49,790 ...is this requirement of liquid water. 74 00:04:49,957 --> 00:04:52,543 So that's why we look for planets that have rocky surfaces... 75 00:04:52,710 --> 00:04:53,878 ...where water could pool... 76 00:04:54,211 --> 00:04:57,131 ...and that are receiving the right amount of energy from the star... 77 00:04:57,298 --> 00:05:01,135 ...where the water wouldn't be locked up in a frozen state because the planet is so cold... 78 00:05:01,302 --> 00:05:04,847 ...nor would it be evaporated away because the planet is too hot. 79 00:05:05,014 --> 00:05:09,435 We call it the Goldilocks Zone, where liquid water could potentially exist. 80 00:05:10,436 --> 00:05:12,646 NARRATOR: Launched in 2009, Kepler stared... 81 00:05:12,813 --> 00:05:17,318 ...at one small patch of the Milky Way for four years straight. 82 00:05:17,485 --> 00:05:21,864 Compared to stars, planets are too tiny for Kepler to spot... 83 00:05:22,656 --> 00:05:24,158 ...but it can detect their shadows. 84 00:05:24,325 --> 00:05:29,580 BATALHA: Every planet orbiting a luminous object is casting a shadow out into space. 85 00:05:29,747 --> 00:05:32,416 The Kepler spacecraft makes use of that fact... 86 00:05:32,583 --> 00:05:37,213 ...waiting for a planet in its orbit about the star... 87 00:05:37,379 --> 00:05:41,175 ...to pass directly between the disc of the star and the spacecraft... 88 00:05:41,675 --> 00:05:46,096 ...and the telescope perceives that as a dimming of light. 89 00:05:46,263 --> 00:05:49,517 NARRATOR: This simple method has revealed thousands of exoplanets. 90 00:05:50,267 --> 00:05:53,646 Planets orbiting other stars in our galaxy. 91 00:05:53,812 --> 00:05:55,022 What we've learned so far... 92 00:05:55,189 --> 00:06:00,569 ...is that literally every star in the galaxy has at least one planet. 93 00:06:01,070 --> 00:06:05,157 There's an amazing diversity of exoplanets out there... 94 00:06:05,324 --> 00:06:07,326 ...and we've found very exotic worlds. 95 00:06:07,993 --> 00:06:12,248 Two hundred light-years away, there is a Saturn-size planet orbiting... 96 00:06:12,414 --> 00:06:14,917 ...not one, but two stars. 97 00:06:15,084 --> 00:06:18,295 So if you were living on a world like Kepler-16b... 98 00:06:18,462 --> 00:06:22,633 ...you would see in the sky two stars rising in the east, setting in the west... 99 00:06:22,800 --> 00:06:27,471 ...continuously changing position as they orbit one another. 100 00:06:30,140 --> 00:06:33,561 This is an artist's rendition of the planet Kepler-10b. 101 00:06:33,727 --> 00:06:39,900 It's orbiting 23 times closer to its parent star than Mercury is to our own sun. 102 00:06:40,067 --> 00:06:45,197 So this star-facing side is just being blasted by stellar radiation... 103 00:06:45,573 --> 00:06:49,660 ...creating temperatures in excess of that required to melt iron. 104 00:06:49,827 --> 00:06:54,123 The planet has an entire hemisphere larger than the Pacific Ocean... 105 00:06:54,290 --> 00:06:57,293 ...which is an ocean, but it's not an ocean of water. 106 00:06:57,459 --> 00:06:59,670 It's an ocean of molten lava. 107 00:07:00,713 --> 00:07:03,048 NARRATOR: Not an attractive destination. 108 00:07:04,717 --> 00:07:08,887 But Kepler recently found us a possible second home. 109 00:07:09,054 --> 00:07:12,766 This is an artist's concept of the Kepler-186 planetary system. 110 00:07:12,933 --> 00:07:15,978 Five planets orbiting this M-type star... 111 00:07:16,145 --> 00:07:20,274 ...and the outermost planet is Kepler-186f. 112 00:07:21,108 --> 00:07:26,447 Our first discovery of an Earth-size planet in the habitable zone of a normal star. 113 00:07:26,614 --> 00:07:32,369 When I think about Kepler-186f, I try to imagine it as a real place... 114 00:07:32,536 --> 00:07:34,788 ...because it is a real place. 115 00:07:34,955 --> 00:07:38,000 We know that it could be rocky, it's the same size as Earth... 116 00:07:38,167 --> 00:07:40,836 ...so I do imagine a rocky surface. 117 00:07:41,545 --> 00:07:45,591 We don't know that it has a liquid ocean, but we can certainly imagine one. 118 00:07:46,091 --> 00:07:48,427 And then, all of a sudden in your imagination... 119 00:07:48,594 --> 00:07:51,388 ...you internalize the existence of this world out there... 120 00:07:51,555 --> 00:07:54,892 ...that there is a place that could be very, very much like Earth. 121 00:07:55,976 --> 00:08:00,481 NARRATOR: So when do we set sail for these distant shores? 122 00:08:00,648 --> 00:08:02,650 Reality check. 123 00:08:02,941 --> 00:08:08,113 Kepler-186f is nearly 3 quadrillion miles from Earth. 124 00:08:08,280 --> 00:08:11,116 Otherwise put, 500 light-years away. 125 00:08:11,909 --> 00:08:16,163 That's a journey of 500 years at the speed of light. 126 00:08:16,455 --> 00:08:19,583 But no thing can travel as fast as light. 127 00:08:19,750 --> 00:08:22,753 At best, our spacecrafts are thousands of times slower. 128 00:08:23,087 --> 00:08:25,756 Even the spaceships in Interstellar don't come close. 129 00:08:25,923 --> 00:08:29,093 BRAND: We need the bravest humans to find us a new home. 130 00:08:29,259 --> 00:08:32,304 COOPER: But the nearest star is over a thousand years away. 131 00:08:32,471 --> 00:08:34,098 - Hence the bravery. - Okay. 132 00:08:34,473 --> 00:08:38,018 NARRATOR: So how do they reach new worlds beyond our solar system? 133 00:08:39,436 --> 00:08:42,815 They take a walk on the warp side of space and time. 134 00:08:47,403 --> 00:08:49,238 You have no idea when you're coming back. 135 00:08:50,322 --> 00:08:53,200 AMELIA: Couldn't you have told her you were going to save the world? 136 00:08:53,367 --> 00:08:54,618 No. 137 00:08:56,120 --> 00:08:58,247 I'm coming back. 138 00:08:58,914 --> 00:09:04,461 NARRATOR: When we journey to a far-off place, we travel not just in space but also in time... 139 00:09:04,628 --> 00:09:07,256 ...as we move into the future. 140 00:09:08,632 --> 00:09:15,305 Until about a century ago, scientists believed that space and time were entirely separate. 141 00:09:16,265 --> 00:09:22,646 Theoretical physicist Sean Carroll explains how Albert Einstein overturned that idea. 142 00:09:23,021 --> 00:09:24,857 CARROLL: One of Einstein's great insights... 143 00:09:25,023 --> 00:09:27,484 ...was that space and time were related to each other... 144 00:09:27,651 --> 00:09:29,528 ...where you have space and you have time. 145 00:09:29,695 --> 00:09:33,449 Einstein says, "There's only one thing which we call space-time." 146 00:09:34,616 --> 00:09:37,035 And then he says, "This space-time thing... 147 00:09:37,202 --> 00:09:41,206 ...it's not just the stage on which all the action plays out. 148 00:09:41,373 --> 00:09:42,541 It's an actor itself." 149 00:09:45,711 --> 00:09:50,382 Space-time can change, it can move, it can bend, and it can warp. 150 00:09:53,677 --> 00:09:59,057 NARRATOR: Einstein's theory of relativity states that space-time is like a flexible fabric. 151 00:09:59,224 --> 00:10:06,106 The objects embedded in it: The sun, planets, even us, warp that fabric. 152 00:10:06,607 --> 00:10:10,778 And the consequence of that warping is what we call gravity. 153 00:10:10,944 --> 00:10:14,907 The more massive the object, the more space-time is warped... 154 00:10:15,073 --> 00:10:17,451 ...and the greater the gravity. 155 00:10:21,914 --> 00:10:23,415 We feel gravity. 156 00:10:25,459 --> 00:10:29,588 The flexibility of space-time is harder to grasp on a gut level... 157 00:10:29,755 --> 00:10:32,382 ...but its effects are measurable. 158 00:10:35,260 --> 00:10:41,266 As Sean demonstrates, the greater the gravity, the more slowly time flows. 159 00:10:41,433 --> 00:10:44,228 CARROLL: For example, if I were on the ground floor with a clock... 160 00:10:44,394 --> 00:10:46,396 ...a super accurate atomic clock... 161 00:10:46,563 --> 00:10:49,233 ...and a twin of mine was up on the top floor of a building... 162 00:10:49,399 --> 00:10:51,235 ...with an equally accurate atomic clock... 163 00:10:51,401 --> 00:10:55,823 ...if we later on compared them, mine would have ticked off fewer seconds. 164 00:10:57,241 --> 00:11:01,161 NARRATOR: On the ground floor, Sean experiences slightly more gravity... 165 00:11:01,328 --> 00:11:03,539 ...than his twin on the top floor. 166 00:11:03,705 --> 00:11:07,417 He also experiences slightly less time than his twin. 167 00:11:08,126 --> 00:11:11,213 The difference is tiny, but real. 168 00:11:11,380 --> 00:11:13,340 And there are practical applications. 169 00:11:13,507 --> 00:11:17,177 CARROLL: For example, the GPS system, the Global Positioning System... 170 00:11:17,344 --> 00:11:20,556 ...that is a very, very precise set of clocks... 171 00:11:20,722 --> 00:11:23,016 ...on satellites orbiting around the Earth... 172 00:11:23,183 --> 00:11:27,396 ...and that orbit is in a slightly different gravitational field than we are in down here. 173 00:11:27,563 --> 00:11:32,150 So the fact that time moves differently here on the surface of the Earth... 174 00:11:32,317 --> 00:11:34,653 ...than in the satellite orbit, is very, very important... 175 00:11:34,820 --> 00:11:36,905 ...to getting the GPS to work correctly. 176 00:11:37,573 --> 00:11:41,743 NARRATOR: Time on a GPS satellite clock advances faster than a clock on Earth... 177 00:11:41,910 --> 00:11:44,246 ...by about 38 microseconds per day... 178 00:11:44,621 --> 00:11:46,999 ...so the system's computers correct for that. 179 00:11:49,585 --> 00:11:52,754 Motion also affects our experience of space-time. 180 00:11:52,921 --> 00:11:55,674 CARROLL: The best way to say it is just staying still... 181 00:11:55,841 --> 00:11:58,594 ...means that you experience the most time that you can. 182 00:11:58,760 --> 00:12:02,598 Moving around and doing things means you experience less time. 183 00:12:02,764 --> 00:12:07,603 NARRATOR: Let's revisit Sean at the wheel of his car and his twin on a park bench. 184 00:12:07,769 --> 00:12:10,898 If you move out on your car, and then you come back... 185 00:12:11,273 --> 00:12:13,859 ...compared to the person who stayed behind... 186 00:12:14,026 --> 00:12:16,445 ...your clock that you took with you on that journey... 187 00:12:16,612 --> 00:12:20,407 ...will have experienced a little bit less time than the one who stayed behind. 188 00:12:22,910 --> 00:12:25,913 NARRATOR: We normally move too slowly to notice the effect. 189 00:12:26,747 --> 00:12:29,958 But if Sean could drive near the speed of light... 190 00:12:31,460 --> 00:12:35,297 ...he could race across the United States and back again a million times... 191 00:12:35,464 --> 00:12:38,383 ...and experience less than a second of time... 192 00:12:38,550 --> 00:12:40,344 ...while the twin he left behind... 193 00:12:40,510 --> 00:12:43,430 ...would endure hours of waiting for Sean's return. 194 00:12:44,681 --> 00:12:49,561 In other words, Sean would've traveled into the future compared to his twin. 195 00:12:51,355 --> 00:12:53,607 This means space travel may get tricky in years to come. 196 00:12:54,524 --> 00:12:58,445 The faster our spaceships, the greater the gravity fields we encounter... 197 00:12:58,612 --> 00:13:02,491 ...the further out of sync we may become with those we leave behind. 198 00:13:02,658 --> 00:13:06,203 COOPER: So if we find a home, then what? 199 00:13:06,370 --> 00:13:08,789 Every hour is seven years back on Earth. 200 00:13:09,206 --> 00:13:14,836 NARRATOR: The relativity of time is the source of hardship and heartbreak in Interstellar. 201 00:13:16,171 --> 00:13:18,966 The theory of relativity is fascinating all by itself... 202 00:13:19,132 --> 00:13:22,052 ...but it immediately becomes something very emotional... 203 00:13:22,219 --> 00:13:25,514 ...when you talk about the distances between people. 204 00:13:26,556 --> 00:13:29,267 You know, we all spend time away from our families. 205 00:13:29,434 --> 00:13:33,981 I just thought, what if you could take that to its logical and very bittersweet extreme? 206 00:13:34,147 --> 00:13:38,402 NOLAN: For me, it was very exciting to be able to examine the concept... 207 00:13:38,568 --> 00:13:40,946 ...of the subjective experience of time. 208 00:13:41,113 --> 00:13:43,657 It's really the first time I've had an objective structure... 209 00:13:43,824 --> 00:13:46,743 ...around the film saying that time literally is relative... 210 00:13:46,910 --> 00:13:50,288 ...that we all experience time differently depending on where we are in the universe. 211 00:13:51,248 --> 00:13:54,126 NARRATOR: But the warping of space-time may also provide shortcuts... 212 00:13:54,584 --> 00:13:57,212 ...that could make interstellar travel a snap. 213 00:13:58,505 --> 00:13:59,715 Wormholes. 214 00:14:00,716 --> 00:14:02,509 They're a staple of science fiction... 215 00:14:03,927 --> 00:14:06,346 ...but they're based on real science. 216 00:14:06,972 --> 00:14:12,060 Einstein's relativistic laws govern the warping of space and time... 217 00:14:12,227 --> 00:14:16,356 ...and they say that wormholes might exist, they could exist. 218 00:14:16,815 --> 00:14:20,235 So this dates all the way back to 1916. 219 00:14:22,154 --> 00:14:26,450 CARROLL: A wormhole is a particular way that space and time can be curved. 220 00:14:26,616 --> 00:14:30,996 It's like adding a little tube that connects two parts of space. 221 00:14:31,621 --> 00:14:36,626 The basic idea is that if you're an ant and you live on the surface of the apple... 222 00:14:36,793 --> 00:14:39,421 ...the surface of the apple is your entire universe. 223 00:14:40,047 --> 00:14:44,301 You can go around the outside through the universe itself... 224 00:14:44,468 --> 00:14:47,179 ...or you can go through the wormhole. 225 00:14:47,471 --> 00:14:52,142 NARRATOR: But Einstein's equations also predict that if wormholes do form in nature... 226 00:14:52,309 --> 00:14:54,644 ...they may be subatomic in size... 227 00:14:54,811 --> 00:14:58,899 ...and exist for only fractions of a second before closing off. 228 00:15:00,233 --> 00:15:04,279 Theoretically, what would it take to keep a wormhole open... 229 00:15:04,446 --> 00:15:07,324 ...and make it big enough to accommodate a spaceship? 230 00:15:07,491 --> 00:15:10,869 THORNE: It turns out that in order to hold a wormhole open... 231 00:15:11,036 --> 00:15:14,831 ...so it doesn't crunch off and kill you when you try to go through... 232 00:15:14,998 --> 00:15:21,630 ...that you have to have the wormhole threaded by a negative mass or negative energy. 233 00:15:21,797 --> 00:15:24,007 Einstein says mass and energy are equivalent. 234 00:15:24,758 --> 00:15:30,138 NARRATOR: Almost all the forms of matter we know have positive mass and exert gravity. 235 00:15:31,556 --> 00:15:34,017 Negative mass would exert antigravity... 236 00:15:34,184 --> 00:15:37,896 ...and repel the walls of a wormhole to keep it open. 237 00:15:38,063 --> 00:15:43,401 Strangely, it is true that negative energy can exist... 238 00:15:43,568 --> 00:15:48,115 ...and it's been created in the laboratory, but only in very tiny amounts. 239 00:15:49,074 --> 00:15:50,742 NARRATOR: It would take vast quantities... 240 00:15:50,909 --> 00:15:54,412 ...to prop open a wormhole large enough for a spaceship. 241 00:15:55,080 --> 00:15:57,582 But just maybe, in the future... 242 00:15:57,749 --> 00:16:02,546 ...engineers will devise advanced technologies to do just that. 243 00:16:02,712 --> 00:16:06,925 Today it's an educated guess, maybe I should say a half-educated guess... 244 00:16:07,092 --> 00:16:10,428 ...that wormholes cannot exist in our universe... 245 00:16:10,595 --> 00:16:12,597 ...but we're far from sure of that. 246 00:16:12,764 --> 00:16:15,642 CARROLL: The truth is, we just don't know right now. 247 00:16:15,809 --> 00:16:18,562 We don't understand the laws of physics well enough to say for sure... 248 00:16:18,728 --> 00:16:20,355 ...whether or not wormholes are possible. 249 00:16:21,148 --> 00:16:25,861 NARRATOR: But since they're not impossible, they're fair game for a filmmaker. 250 00:16:26,027 --> 00:16:29,698 I was very excited about the idea of focusing on a family... 251 00:16:30,031 --> 00:16:31,616 ...who would be the pioneers... 252 00:16:31,783 --> 00:16:36,037 ...who would experience some of the extraordinary features of astrophysics... 253 00:16:36,204 --> 00:16:41,084 ...particularly the idea of a wormhole that would allow us to travel to distant stars. 254 00:16:42,794 --> 00:16:45,338 NARRATOR: To create a wormhole based on real science... 255 00:16:45,505 --> 00:16:48,758 ...Visual Effects supervisor Paul Franklin turned to Kip Thorne. 256 00:16:50,844 --> 00:16:54,472 FRANKLIN: The popular image of what a wormhole might look like... 257 00:16:54,639 --> 00:16:56,600 ...is literally just a hole in space. 258 00:16:56,766 --> 00:17:00,896 It sits on an invisible surface, you see stuff sliding down the sides... 259 00:17:01,062 --> 00:17:03,231 ...and disappearing down the drain, as it were. 260 00:17:03,398 --> 00:17:05,984 And right in that first conversation, Kip showed me an image... 261 00:17:06,151 --> 00:17:08,987 ...of that kind of classical fantasy image of these things... 262 00:17:09,154 --> 00:17:13,491 ...and said, "This is all wrong." Ha, ha. "This is not how it is." 263 00:17:13,825 --> 00:17:17,746 NARRATOR: Kip worked out the scientific equations that define the wormhole... 264 00:17:17,913 --> 00:17:20,457 ...and sent them to Paul's animators back in London. 265 00:17:20,624 --> 00:17:24,419 THORNE: And so for the movie, I built a mathematical model wormhole... 266 00:17:24,586 --> 00:17:27,964 ...based on Einstein's relativity equations. 267 00:17:28,131 --> 00:17:32,844 Paul, Kip and myself, we discussed, "Okay, we'll visualize the thing. 268 00:17:33,011 --> 00:17:36,014 We'll simulate the thing exactly as the calculations say." 269 00:17:36,181 --> 00:17:39,059 And Paul Franklin and his team, they were thrilled to get algorithms... 270 00:17:39,226 --> 00:17:42,687 ...that were the absolute latest, most interesting and up-to-the-minute. 271 00:17:42,854 --> 00:17:44,231 MAN: Now we can go to the other one. 272 00:17:44,397 --> 00:17:46,816 The wormhole is a three-dimensional hole in space. 273 00:17:46,983 --> 00:17:49,945 What do you get if you take a Circle and sweep it out in three dimensions? 274 00:17:50,111 --> 00:17:51,363 You get a sphere. 275 00:17:51,529 --> 00:17:55,742 So the wormhole almost feels like a crystal ball hanging in space. 276 00:17:58,620 --> 00:18:02,332 THORNE: I don't think anybody had ever really done this kind of visualization before. 277 00:18:02,499 --> 00:18:03,583 This is really unique. 278 00:18:03,750 --> 00:18:08,296 Uh, first time for me, as well as for you and the audience. 279 00:18:08,463 --> 00:18:09,547 Absolutely, yes. 280 00:18:12,008 --> 00:18:14,928 NARRATOR: In Interstellar, crew members take a giant leap of faith... 281 00:18:15,095 --> 00:18:17,389 ...When they plunge into a wormhole. 282 00:18:17,555 --> 00:18:20,100 DOYLE: You can't think about your family. You have to think bigger. 283 00:18:20,475 --> 00:18:24,312 COOPER: I am thinking about my family and millions of other families. 284 00:18:24,479 --> 00:18:27,482 AMELIA: You might have to decide between seeing your children again... 285 00:18:27,649 --> 00:18:29,276 ...and the future of the human race. 286 00:18:29,943 --> 00:18:33,905 NARRATOR: Beyond the wormhole, the crew Will face a far greater challenge: 287 00:18:34,531 --> 00:18:38,285 To navigate the perils of a black hole. 288 00:18:39,953 --> 00:18:43,748 For a filmmaker, that threat is full of dramatic possibilities. 289 00:18:45,041 --> 00:18:49,629 NOLAN: When you venture out into a story about a man against the elements... 290 00:18:49,796 --> 00:18:56,386 ...visualizing the threat against our protagonist become very much more exotic. 291 00:18:56,886 --> 00:19:01,975 Deep, deep space gives you a very, very fresh approach. 292 00:19:02,851 --> 00:19:05,687 NARRATOR: Black holes were predicted by Einstein's equations... 293 00:19:05,854 --> 00:19:08,648 ...but physicists questioned whether they could really exist. 294 00:19:08,815 --> 00:19:11,318 THORNE: A black hole is a strange beast. 295 00:19:11,484 --> 00:19:15,030 If this were a black hole, then instead of a rubber surface... 296 00:19:15,196 --> 00:19:18,408 ...it would have a surface that is made of absolutely nothing... 297 00:19:18,575 --> 00:19:21,244 ...except warped space and time. 298 00:19:22,871 --> 00:19:25,540 It's a place where gravity is so strong... 299 00:19:25,707 --> 00:19:29,461 ...that if anything falls into the black hole, it can never get back out. 300 00:19:29,627 --> 00:19:31,963 If you fall in, you can't send signals back out. 301 00:19:32,130 --> 00:19:34,257 Light can't get out from the interior. 302 00:19:36,051 --> 00:19:38,636 CARROLL: So you might ask, how would that ever happen? 303 00:19:38,803 --> 00:19:43,433 In outer space, you can get so much mass together, like in a super-massive star... 304 00:19:43,600 --> 00:19:46,853 ...that the gravity just becomes stronger and stronger and stronger... 305 00:19:47,020 --> 00:19:51,316 ...and eventually the pressure that matter exerts on itself can't keep up. 306 00:19:52,275 --> 00:19:54,903 And everything collapses, there's a big explosion. 307 00:19:55,070 --> 00:19:59,032 Some of the stuff is blown away, but the rest of it collapses into a black hole. 308 00:20:00,742 --> 00:20:04,913 NARRATOR: A black hole that spins on its axis drags the very space around it... 309 00:20:05,080 --> 00:20:09,918 ...into a whirling motion that pulls stars and planets into orbit. 310 00:20:10,085 --> 00:20:14,089 Closer in, gravity increases like a riptide. 311 00:20:14,255 --> 00:20:18,760 At a boundary called the event horizon, gravity becomes so extreme... 312 00:20:18,927 --> 00:20:22,305 ...that nothing can escape being pulled into the heart of the beast... 313 00:20:22,472 --> 00:20:23,890 ...and lost forever. 314 00:20:24,516 --> 00:20:28,353 GHEZ: Black holes are simple, and yet they have a lot of character. 315 00:20:28,520 --> 00:20:30,522 It's almost like they can take on personalities. 316 00:20:30,688 --> 00:20:35,026 Um, they can be picky eaters, urn, they can be energetic. 317 00:20:35,193 --> 00:20:36,903 And what you're seeing and describing... 318 00:20:37,070 --> 00:20:39,906 ...is really how the black hole interacts with the environment. 319 00:20:40,865 --> 00:20:43,368 NARRATOR: UCLA astronomer Andrea Ghez... 320 00:20:43,535 --> 00:20:44,744 Looks like this is Sagi's star. 321 00:20:44,911 --> 00:20:46,871 NARRATOR: ...is an expert on black hole detection. 322 00:20:47,038 --> 00:20:49,040 - Must be this one, right? - I think it's that one. 323 00:20:49,207 --> 00:20:53,420 NARRATOR: She played a key role investigating what had long been a scientific hunch. 324 00:20:53,586 --> 00:20:57,006 That a huge black hole lives at the center of the Milky Way. 325 00:20:57,173 --> 00:20:58,341 It's looking good. 326 00:20:58,508 --> 00:21:01,136 NARRATOR: Astronomers knew the heart of our galaxy was buzzing... 327 00:21:01,302 --> 00:21:05,140 ...with gas, dust and millions of stars. 328 00:21:05,306 --> 00:21:08,643 Some powerful force appeared to be driving this hubbub. 329 00:21:08,810 --> 00:21:11,187 Could it be a black hole? 330 00:21:12,105 --> 00:21:15,024 Ground telescopes just couldn't produce sharp images of the region... 331 00:21:16,067 --> 00:21:21,406 ...then a technique called adaptive optics vastly improved the view. 332 00:21:21,573 --> 00:21:25,243 This is what it looks like before you use advanced technology. 333 00:21:25,743 --> 00:21:26,995 It's a blurry mess... 334 00:21:27,162 --> 00:21:30,832 ...and now you can see the individual stars with adaptive optics turned on. 335 00:21:30,999 --> 00:21:35,128 So each point of light here is associated with an individual star. 336 00:21:36,588 --> 00:21:41,509 NARRATOR: Andrea put that technique to work at the Keck Observatory in Hawaii. 337 00:21:42,886 --> 00:21:44,387 GHEZ: This is a road map. 338 00:21:44,554 --> 00:21:48,183 NARRATOR: And she and her team began to track the stars at the center of the Milky Way. 339 00:21:48,349 --> 00:21:50,727 GHEZ: And that's the center of our galaxy. 340 00:21:50,894 --> 00:21:54,063 The very first year that we took the data was in 1995. 341 00:21:55,106 --> 00:21:59,110 Then we go back to the telescope in '96, then we take our second image... 342 00:21:59,277 --> 00:22:01,529 ...and you have two pictures, and you can compare them. 343 00:22:03,072 --> 00:22:07,076 NARRATOR: Andrea wanted to see if the stars were orbiting a single source of gravity... 344 00:22:07,410 --> 00:22:10,205 ...but stars can take years to complete an orbit. 345 00:22:10,830 --> 00:22:13,333 GHEZ: And so it was really important that we kept going... 346 00:22:13,500 --> 00:22:18,254 ...and by 2000 we finally started to see the star's curve. 347 00:22:18,421 --> 00:22:23,051 In other words, the gravitational influence of the black hole, um... 348 00:22:23,218 --> 00:22:27,597 ...had made those stars go from straight lines to starting to bend. 349 00:22:27,764 --> 00:22:29,557 Precise enough to see that curvature. 350 00:22:29,724 --> 00:22:34,312 NARRATOR: Year by year, Andrea and her team built their case. 351 00:22:34,479 --> 00:22:38,566 This animation represents, uh, 20 years of work... 352 00:22:38,733 --> 00:22:45,657 ...and it tells you that there is a black hole, and exactly how massive it is. 353 00:22:45,823 --> 00:22:48,910 NARRATOR: Andrea's painstaking project revealed a monster... 354 00:22:49,077 --> 00:22:52,330 ...with more than 4 million times the mass of our sun... 355 00:22:52,497 --> 00:22:55,792 ...at the center of our Milky Way. 356 00:22:56,417 --> 00:23:00,797 Today, scientists are hunting black holes with new tools. 357 00:23:00,964 --> 00:23:06,219 Caltech astrophysicist Fiona Harrison scans the skies with NuSTAR... 358 00:23:06,386 --> 00:23:09,931 ...a telescope that looks at the universe in high-energy x-rays. 359 00:23:11,140 --> 00:23:13,560 HARRISON: The black hole itself doesn't emit light... 360 00:23:13,726 --> 00:23:16,771 ...but dust and gas falls onto the black holes... 361 00:23:16,938 --> 00:23:22,860 ...and in doing so, it heats up, and it emits x-rays. 362 00:23:23,570 --> 00:23:28,074 NARRATOR: NuSTAR captures black holes in the process of feasting on matter... 363 00:23:28,241 --> 00:23:31,578 ...and the telescope is spotting them all over the place. 364 00:23:31,953 --> 00:23:36,958 HARRISON: It's really only 10, 20 years ago that we thought black holes were rare. 365 00:23:37,125 --> 00:23:40,128 We now know that every galaxy, like our Milky Way... 366 00:23:40,295 --> 00:23:43,089 ...has a massive black hole at its heart. 367 00:23:43,590 --> 00:23:48,761 80 rather than just being curiosities, they're actually fundamentally important... 368 00:23:48,928 --> 00:23:51,472 ...to why the universe is the way it is. 369 00:23:52,056 --> 00:23:55,560 NARRATOR: So is the Earth at risk of getting swallowed by a black hole? 370 00:23:56,311 --> 00:23:59,314 HARRISON: Even though we have black holes sprinkled throughout the galaxy... 371 00:23:59,480 --> 00:24:01,107 ...we're in absolutely no danger. 372 00:24:01,274 --> 00:24:05,028 It's a common misconception that black holes might suck the Earth. 373 00:24:05,194 --> 00:24:08,531 Well, there's no sucking going on, it's just normal gravity. 374 00:24:09,991 --> 00:24:11,826 It's just when you get very close to it... 375 00:24:11,993 --> 00:24:15,038 ...that there's a region from which light can't even escape... 376 00:24:15,204 --> 00:24:18,041 ...and Earth is not gonna do that. 377 00:24:18,916 --> 00:24:20,126 NARRATOR: But in Interstellar... 378 00:24:20,293 --> 00:24:23,254 ...crew members have a precariously close encounter with a black hole. 379 00:24:23,713 --> 00:24:25,381 COOPER: Oh, we are not prepared for this. 380 00:24:25,757 --> 00:24:28,384 NARRATOR: What would the beast look like to them? 381 00:24:28,551 --> 00:24:30,553 One of the things that Kip was very insistent on... 382 00:24:30,720 --> 00:24:34,432 ...is that the black hole, it's spherical, but it's absolutely black. 383 00:24:34,599 --> 00:24:36,225 It has no surface detail. 384 00:24:36,392 --> 00:24:39,187 Doesn't give shadows or highlights or anything. 385 00:24:39,354 --> 00:24:42,357 But then early on, we were talking about accretion disks. 386 00:24:42,774 --> 00:24:47,779 And that gave us a way to define the spherical shape of the thing. 387 00:24:47,945 --> 00:24:52,325 NARRATOR: A black hole's accretion disk is made up of gas and dust and magnetic fields... 388 00:24:52,492 --> 00:24:53,910 ...that spin at high speeds... 389 00:24:54,410 --> 00:24:56,996 ...radiating heat and light. 390 00:24:58,373 --> 00:25:02,418 The black hole's gravity would actually bend that light like a camera lens... 391 00:25:02,585 --> 00:25:04,337 ...in ways that Kip would calculate. 392 00:25:04,796 --> 00:25:09,801 THORNE: I worked out the equations for tracing light rays traveling around the black hole... 393 00:25:09,967 --> 00:25:15,431 ...to see what the disk would look like if you were in a spacecraft looking at it up close. 394 00:25:15,598 --> 00:25:18,393 NARRATOR: And Paul's team brought the mathematics to life. 395 00:25:18,559 --> 00:25:22,313 We were really able to use a very, very accurate representation... 396 00:25:22,480 --> 00:25:26,693 ...of the gravitational lens and the effects of gravity and light around the black hole. 397 00:25:26,859 --> 00:25:32,240 Uh, because what the algorithms gave us was extremely spectacular. 398 00:25:33,991 --> 00:25:36,244 NARRATOR: Even Kip was surprised. 399 00:25:36,411 --> 00:25:38,579 You see the disk in front... 400 00:25:38,746 --> 00:25:40,206 ...and then when it goes around... 401 00:25:40,373 --> 00:25:44,419 ...you see the disk wrap up around the top of the black hole... 402 00:25:44,585 --> 00:25:46,546 ...and wrap around the bottom of the black hole. 403 00:25:49,716 --> 00:25:51,968 I had guessed it would look more or less like this... 404 00:25:52,135 --> 00:25:54,762 ...but knowing it intellectually is different than feeling it... 405 00:25:54,929 --> 00:25:57,181 ...than absorbing it, than seeing it. 406 00:25:57,849 --> 00:25:59,642 It just blew me away. 407 00:26:00,393 --> 00:26:01,978 NARRATOR: But this brilliant depiction... 408 00:26:02,145 --> 00:26:05,565 ...still can't tell us what happens in the heart of a black hole... 409 00:26:05,732 --> 00:26:07,483 ...beyond the event horizon. 410 00:26:08,901 --> 00:26:14,782 What would happen to an astronaut daring or crazy enough to dive in feet-first? 411 00:26:14,949 --> 00:26:16,993 THORNE: In the simplest descriptions of this... 412 00:26:17,160 --> 00:26:20,788 ...the descriptions that you will find in most books that you read... 413 00:26:20,955 --> 00:26:22,915 ...you're simply stretched from head to foot... 414 00:26:23,082 --> 00:26:28,880 ...and squeezed from the side by tidal forces, "spaghettified" is what it often says. 415 00:26:29,380 --> 00:26:32,675 You're spaghettified as you fall in and you're destroyed. 416 00:26:33,134 --> 00:26:34,969 That's the standard story. 417 00:26:39,599 --> 00:26:42,769 NARRATOR: The truth is, all the laws of physics that we know... 418 00:26:42,935 --> 00:26:46,189 ...break down in the heart of a black hole. 419 00:26:46,355 --> 00:26:50,651 Physicists are still working on exactly what happens there. 420 00:26:52,069 --> 00:26:53,738 That's the gravity well, though, isn't it? 421 00:26:53,905 --> 00:26:59,118 When we talk to non-physicists, we will often say it's the gravity well. 422 00:26:59,285 --> 00:27:01,496 So you've been lying to us all these years. 423 00:27:01,662 --> 00:27:04,832 You know how these things go, there are lies and there are "lies." 424 00:27:04,999 --> 00:27:06,042 I know, but now... 425 00:27:06,459 --> 00:27:11,756 The movie Interstellar deals with physics that is well-understood, well-established. 426 00:27:11,923 --> 00:27:15,051 It deals with physics where we make educated guesses... 427 00:27:15,218 --> 00:27:17,929 ...and we're almost sure, but not 100 percent sure of our guesses. 428 00:27:19,055 --> 00:27:22,809 And it deals with physics at the frontiers of human understanding... 429 00:27:22,975 --> 00:27:24,811 ...where we have to speculate... 430 00:27:24,977 --> 00:27:26,813 ...and when you get beyond those frontiers... 431 00:27:26,979 --> 00:27:30,066 ...Interstellar works hard to align itself... 432 00:27:30,233 --> 00:27:34,028 ...with the best speculations a scientist could imagine. 433 00:27:34,195 --> 00:27:39,283 We're struggling very hard as filmmakers to try and explain, uh... 434 00:27:39,450 --> 00:27:42,912 ...these scientific concepts, these sort of abstract ideas... 435 00:27:43,079 --> 00:27:47,208 ...in a subjective way and a way that you can actually experience and feel something about. 436 00:27:48,960 --> 00:27:53,840 NARRATOR: Interstellar mines that gray area where new ideas percolate... 437 00:27:54,006 --> 00:27:58,886 ...and taps deep into questions about the nature of the universe. 438 00:28:04,392 --> 00:28:08,354 In Interstellar, telescopes on Earth first detect the presence of a wormhole. 439 00:28:10,064 --> 00:28:14,861 It shows up as a gravitational anomaly that distorts the view of space. 440 00:28:15,444 --> 00:28:18,781 We made the wormhole not have all that strong a gravity. 441 00:28:18,948 --> 00:28:20,700 But why the wormhole? 442 00:28:21,075 --> 00:28:24,328 Because then you have a reason for your trip around it. 443 00:28:24,495 --> 00:28:27,373 I feel uncomfortable with the wormhole having that much gravity. 444 00:28:27,540 --> 00:28:30,293 THORNE: When I first began working with Christopher Nolan... 445 00:28:30,459 --> 00:28:33,254 ...he wanted a wormhole that had rather gentle gravity... 446 00:28:33,421 --> 00:28:35,715 ...so we discussed how big the wormhole should be... 447 00:28:35,882 --> 00:28:39,427 ...and agreed that it should be just barely big enough... 448 00:28:39,594 --> 00:28:41,387 ...that it could be seen from Earth... 449 00:28:41,554 --> 00:28:44,223 ...through the bending of light around the wormhole... 450 00:28:44,390 --> 00:28:46,559 ...by the wormhole's warped space. 451 00:28:46,726 --> 00:28:50,563 NARRATOR: Kip Thorne worked out just the right gravity for Interstellar's wormhole... 452 00:28:50,980 --> 00:28:55,359 ...using equations based on Einstein's theory of general relativity. 453 00:28:55,526 --> 00:29:01,699 As we've learned, that theory states that objects warp space-time, creating gravity. 454 00:29:02,533 --> 00:29:06,495 It also predicts that when objects move, they generate a pulse... 455 00:29:06,662 --> 00:29:10,666 ...that propagates through space-time, a bit like waves through water. 456 00:29:13,628 --> 00:29:18,341 These gravitational waves have never been directly observed. 457 00:29:18,507 --> 00:29:21,260 They would be small and hard to detect... 458 00:29:21,427 --> 00:29:25,806 ...unless they were generated by a massively violent motion. 459 00:29:27,350 --> 00:29:30,394 Like the birth of the universe. 460 00:29:33,564 --> 00:29:36,442 Physicists developed their big bang theory... 461 00:29:36,609 --> 00:29:41,530 ...in part by observing that today the universe is expanding. 462 00:29:42,740 --> 00:29:48,329 Galaxies are moving away from each other like raisins in a rising loaf of bread... 463 00:29:48,996 --> 00:29:54,293 ...which suggests that in the distant past, the universe must have been much smaller. 464 00:29:54,460 --> 00:29:59,090 CARROLL: If you wind the movie backwards, in the past, everything was closer together... 465 00:29:59,256 --> 00:30:04,220 ...and you plug that idea into the equations that Einstein gives us. 466 00:30:04,595 --> 00:30:08,766 And there's a moment, which we now know was about 14 billion years ago... 467 00:30:08,933 --> 00:30:10,977 ...when everything was on top of everything else... 468 00:30:11,143 --> 00:30:15,815 ...when the density of stuff in the universe was apparently infinitely big. 469 00:30:18,609 --> 00:30:22,905 NARRATOR: Then a powerful force triggered an expansion of space itself. 470 00:30:23,072 --> 00:30:28,536 Faster than the speed of light, a theory called cosmic inflation. 471 00:30:28,703 --> 00:30:34,458 And the theory said that this inflation should've taken fluctuations in the shape of space... 472 00:30:34,625 --> 00:30:37,837 ...and amplified them so they got much stronger. 473 00:30:39,046 --> 00:30:41,382 And they become gravitational waves... 474 00:30:41,549 --> 00:30:45,469 ...producing ripples in the fabric of space and time. 475 00:30:46,637 --> 00:30:48,848 NARRATOR: If we could detect those ripples today... 476 00:30:49,015 --> 00:30:52,184 ...it would help us understand how the big bang banged. 477 00:30:52,351 --> 00:30:55,062 BOOK: The trick was always how were we going to measure such a thing. 478 00:30:55,229 --> 00:30:57,106 And that led us to propose and develop... 479 00:30:57,273 --> 00:31:00,151 ...this very specialized experiment, um... 480 00:31:00,317 --> 00:31:04,989 ...which one of my colleagues referred to gleefully as a wild-goose chase. 481 00:31:06,198 --> 00:31:10,745 NARRATOR: Caltech physicist Jamie Bock works in experimental cosmology. 482 00:31:10,911 --> 00:31:14,248 BOCK: Experimental cosmology is building experiments... 483 00:31:14,415 --> 00:31:16,709 ...trying to get back to the dawn of time. 484 00:31:16,876 --> 00:31:17,918 You need a hand with that? 485 00:31:18,085 --> 00:31:19,920 NARRATOR: The focus of his latest experiment... 486 00:31:20,087 --> 00:31:21,839 ...Was the oldest light in the universe. 487 00:31:22,173 --> 00:31:26,052 The faint afterglow of the big bang. 488 00:31:26,218 --> 00:31:30,139 Physicists have mapped this cosmic microwave background... 489 00:31:30,306 --> 00:31:32,516 ...across the universe. 490 00:31:33,559 --> 00:31:37,438 If the birth of the universe produced gravitational waves... 491 00:31:37,605 --> 00:31:39,440 ...they would've warped this primordial light... 492 00:31:39,607 --> 00:31:44,195 ...and caused it to be polarized or curled in a specific direction. 493 00:31:44,361 --> 00:31:46,155 BOCK: If one could measure the polarization... 494 00:31:46,322 --> 00:31:48,866 ...and then not only measure it but look at its pattern... 495 00:31:49,033 --> 00:31:51,202 ...there might be kind of a swirly pattern... 496 00:31:51,368 --> 00:31:54,455 ...that would be an indicator of gravitational waves. 497 00:31:55,998 --> 00:32:00,503 NARRATOR: Jamie and his team designed a series of small super-sensitive telescopes... 498 00:32:01,629 --> 00:32:04,715 ...that they installed where the skies are crystal clear. 499 00:32:04,882 --> 00:32:06,884 At the South Pole. 500 00:32:07,510 --> 00:32:10,221 BOOK: The South Pole is the closest we can get to outer space... 501 00:32:10,387 --> 00:32:11,722 ...to make our measurements. 502 00:32:14,183 --> 00:32:17,978 NARRATOR: For eight years, the team's telescopes scanned a patch in the sky... 503 00:32:18,145 --> 00:32:20,606 ...measuring minute differences in the temperature... 504 00:32:20,773 --> 00:32:23,109 ...of the cosmic microwave background... 505 00:32:23,275 --> 00:32:24,944 ...and a pattern emerged. 506 00:32:25,111 --> 00:32:30,449 BOCK: Our results reported that we see this swirly pattern of polarization... 507 00:32:30,616 --> 00:32:34,912 ...that's consistent with, uh, what you expect from gravitational waves. 508 00:32:35,704 --> 00:32:39,416 THORNE: So they didn't really see the gravitational waves from the early universe... 509 00:32:39,583 --> 00:32:43,420 ...but they saw this polarization pattern that was precisely what was predicted... 510 00:32:43,587 --> 00:32:46,090 ...except that it was stronger than expected. 511 00:32:46,715 --> 00:32:49,677 Tells us what went on immediately after the big bang... 512 00:32:49,844 --> 00:32:54,181 ...when the universe was a trillionth of a trillionth of a trillionth of a second old. 513 00:32:54,348 --> 00:32:57,560 So it's seeing almost the creation of the universe. 514 00:32:58,894 --> 00:33:02,523 NARRATOR: The finding must be confirmed by other experiments. 515 00:33:02,690 --> 00:33:07,027 If it holds up, this first evidence for the detection of gravitational waves... 516 00:33:07,194 --> 00:33:11,240 ...will deepen our understanding of the birth of the universe. 517 00:33:12,783 --> 00:33:18,539 And that, by extension, may help us answer an enduring question: 518 00:33:18,914 --> 00:33:20,875 Can we time travel? 519 00:33:21,041 --> 00:33:23,335 CARROLL: You know, it's very easy to travel in time. 520 00:33:23,502 --> 00:33:26,547 Yesterday, I've moved forward 24 hours and here I am. 521 00:33:26,714 --> 00:33:30,092 But that's the only way that it's easy. It's easy to go into the future. 522 00:33:30,259 --> 00:33:34,513 In fact, it's not just easy, it's inevitable. We all move into the future over time. 523 00:33:35,264 --> 00:33:38,893 NARRATOR: But traveling to the past is a different story... 524 00:33:39,226 --> 00:33:42,938 ...because space and time have profoundly different properties. 525 00:33:43,480 --> 00:33:46,734 In space, you can go up, down, left, right, forward, backward. 526 00:33:48,319 --> 00:33:52,031 NARRATOR: We move freely through the three dimensions of space. 527 00:33:52,198 --> 00:33:56,952 In time, we experience its one dimension and a lot less freedom. 528 00:33:57,494 --> 00:34:00,206 CARROLL: Because time has a direction and space does not. 529 00:34:00,372 --> 00:34:02,208 In time, there's a huge difference... 530 00:34:02,374 --> 00:34:05,544 ...between one direction, the future, and the other direction, the past. 531 00:34:05,711 --> 00:34:09,757 For example, you remember the past, but you don't remember the future. 532 00:34:09,924 --> 00:34:12,468 You were younger in the past, we were all younger in the past. 533 00:34:12,635 --> 00:34:15,221 We will all be older. It's all universal to us. 534 00:34:17,890 --> 00:34:21,352 This arrow of time is a little bit mysterious. 535 00:34:21,518 --> 00:34:23,520 We understand the basic underpinnings... 536 00:34:23,687 --> 00:34:27,316 ...in a concept called entropy, the disorderliness of the universe. 537 00:34:28,901 --> 00:34:32,488 NARRATOR: Entropy is the measure of the disorder in a system. 538 00:34:32,655 --> 00:34:36,033 The more ordered a system, the lower its entropy. 539 00:34:38,452 --> 00:34:42,206 The more disordered a system, the higher its entropy. 540 00:34:42,539 --> 00:34:46,961 A classic example of entropy increasing is just mixing cream into coffee. 541 00:34:47,127 --> 00:34:50,047 When the cream and the coffee are separate, that's low entropy. 542 00:34:50,214 --> 00:34:52,299 They're organized. There's the cream, the coffee. 543 00:34:52,466 --> 00:34:55,177 You pour them together, you let them mix together. 544 00:34:55,511 --> 00:34:58,347 Entropy just goes up. Things become more and more disorderly. 545 00:35:02,476 --> 00:35:06,146 And this goes all the way back 14 billion years to the big bang. 546 00:35:07,356 --> 00:35:11,527 NARRATOR: Back then, all the matter in the universe would have been on top of itself. 547 00:35:11,694 --> 00:35:14,655 Density would have been infinite. 548 00:35:14,822 --> 00:35:17,950 It was the epitome of low entropy. 549 00:35:19,994 --> 00:35:24,164 But entropy has been on the rise ever since the big bang. 550 00:35:24,540 --> 00:35:27,042 CARROLL: We think, but we haven't absolutely established... 551 00:35:27,209 --> 00:35:30,921 ...that this general tendency to go from order to disorder... 552 00:35:31,088 --> 00:35:35,217 ...is the single reason why the past is different from the future. 553 00:35:35,384 --> 00:35:39,638 We can't discount in principle the possibility of visiting the past... 554 00:35:39,805 --> 00:35:43,892 ...but all of these weird puzzles that sort of rub us the wrong way... 555 00:35:44,059 --> 00:35:47,855 ...about if I go back into the past and I give myself a really good idea... 556 00:35:48,022 --> 00:35:51,483 ...and then I grow up and become rich off that idea, where did the idea come from? 557 00:35:51,650 --> 00:35:54,153 These kinds of puzzles would evaporate... 558 00:35:54,320 --> 00:35:57,906 ...if we just said, "Well, the laws of physics don't allow you to visit the past." 559 00:35:58,073 --> 00:36:00,284 So that's probably true. 560 00:36:01,577 --> 00:36:05,748 NARRATOR: To contemplate the mysteries of space, time and the universe... 561 00:36:05,914 --> 00:36:08,542 ...can make a person feel mighty small. 562 00:36:08,709 --> 00:36:13,339 Maybe it's best to lower our sights, hunker down and focus on planet Earth. 563 00:36:14,381 --> 00:36:18,010 But that's not really an option for humanity in the long run. 564 00:36:21,555 --> 00:36:25,309 Interstellar depicts a future where living conditions on Earth are grim. 565 00:36:25,476 --> 00:36:30,230 Our mission does not work if the people on Earth are dead by the time we pull it off. 566 00:36:30,689 --> 00:36:33,067 NARRATOR: Failing crops. 567 00:36:33,442 --> 00:36:35,444 Clouds of dust. 568 00:36:37,029 --> 00:36:39,490 Roads clogged with refugees. 569 00:36:39,656 --> 00:36:41,200 Sound familiar? 570 00:36:43,827 --> 00:36:47,289 That's because we've lived through this scenario before. 571 00:36:48,123 --> 00:36:51,585 In the 19308, the Great Plains were hit by extreme drought. 572 00:36:52,378 --> 00:36:55,464 Farmers had plowed up native grasslands. 573 00:36:55,631 --> 00:37:01,011 When crops failed, unprotected topsoil billowed into clouds that darkened the sky for days. 574 00:37:03,514 --> 00:37:07,851 Some 400,000 people lost nearly everything during the dust bowl. 575 00:37:08,185 --> 00:37:12,523 One of America's worst man-made ecological disasters. 576 00:37:15,526 --> 00:37:19,905 It was the model for the calamity depicted in Interstellar. 577 00:37:21,657 --> 00:37:24,618 NOLAN: I really wanted to try and bring the audiences' attention... 578 00:37:24,785 --> 00:37:28,038 ...to the idea that this sort of thing really can happen. 579 00:37:28,205 --> 00:37:32,459 And it struck me that the imagery that you can find... 580 00:37:32,626 --> 00:37:36,004 ...was so much more extraordinary than anything you see in a science fiction film. 581 00:37:36,171 --> 00:37:39,883 And, indeed, in our portrayal of it, we had to frankly water it down. 582 00:37:40,634 --> 00:37:43,846 NARRATOR: But we'd never let a dust bowl happen again, would we? 583 00:37:47,349 --> 00:37:52,438 In recent years, cities in the American Southwest, especially Texas... 584 00:37:52,604 --> 00:37:55,357 ...have been battered by huge dust storms. 585 00:37:55,816 --> 00:38:00,112 They've caused fatal traffic accidents and damaged infrastructure. 586 00:38:00,279 --> 00:38:04,908 The causes are frighteningly familiar to UCLA geographer Greg Okin... 587 00:38:05,075 --> 00:38:08,537 ...an expert on the dynamics of wind and dust. 588 00:38:09,246 --> 00:38:10,831 OKIN: We have wind-erodible soil. 589 00:38:10,998 --> 00:38:13,834 We have agriculture that's disturbed the native vegetation. 590 00:38:14,001 --> 00:38:17,546 We have bare ground because crops fail. 591 00:38:17,713 --> 00:38:19,423 And we have windy conditions. 592 00:38:19,590 --> 00:38:24,595 So all of the same things that happened in the dust bowl are happening now. 593 00:38:26,221 --> 00:38:29,975 NARRATOR: Models of climate change predict higher global temperatures. 594 00:38:30,142 --> 00:38:32,686 That probably means more droughts. 595 00:38:33,395 --> 00:38:36,523 Economic pressures may lead to increased farming of wildlands. 596 00:38:38,525 --> 00:38:42,738 If crops fail due to drought, that could mean more dust. 597 00:38:43,113 --> 00:38:44,907 OKIN: It could happen in China. 598 00:38:45,073 --> 00:38:46,617 It could happen in Africa. 599 00:38:46,783 --> 00:38:51,413 Any of these factors, when they're in place, could cause what we have called the dust bowl. 600 00:38:52,706 --> 00:38:54,374 NARRATOR: And to make matters worse... 601 00:38:55,042 --> 00:38:59,338 ...dust is much dirtier today than it was in the 19303. 602 00:38:59,505 --> 00:39:04,218 OKIN: The dust that is interacting with clouds of pollution from Cities... 603 00:39:04,384 --> 00:39:06,845 ...in urban and industrial activities, um... 604 00:39:07,012 --> 00:39:12,059 ...that actually does appear to also be more noxious than regular dust. 605 00:39:12,935 --> 00:39:17,564 NARRATOR: Winds blow dust across oceans and continents and into our lungs. 606 00:39:17,731 --> 00:39:21,443 Dust, particularly for kids with asthma, is a really big problem. 607 00:39:21,610 --> 00:39:23,529 There's actually quite good evidence... 608 00:39:23,695 --> 00:39:28,784 ...for dust being correlated with pediatric hospital admissions. 609 00:39:28,951 --> 00:39:31,370 That's where the really clear evidence is. 610 00:39:32,663 --> 00:39:35,916 NARRATOR: No one predicted the dust bowl of the 19308. 611 00:39:36,083 --> 00:39:38,168 Today, we should know better. 612 00:39:38,335 --> 00:39:41,964 OKIN: We learned the important lesson that poorly-planned human activity... 613 00:39:42,130 --> 00:39:47,302 ...plus unexpected climate variability can lead to disaster. 614 00:39:47,469 --> 00:39:49,555 There's a lot to worry about. 615 00:39:51,390 --> 00:39:54,643 NARRATOR: Sadly, we don't have a great track record taking care of Mother Earth. 616 00:39:56,228 --> 00:40:01,358 But the planet is also threatened by forces far beyond our control. 617 00:40:05,571 --> 00:40:08,115 February 15th, 2013... 618 00:40:10,325 --> 00:40:14,538 ...a meteor shining brighter than the sun streaks across Siberia. 619 00:40:15,205 --> 00:40:18,166 It's a rock 65 feet in diameter... 620 00:40:18,333 --> 00:40:22,212 ...and when it explodes in midair, it releases more than 20 times the energy... 621 00:40:22,379 --> 00:40:25,090 ...of the bomb dropped on Hiroshima. 622 00:40:25,716 --> 00:40:27,384 [SCREAMING] 623 00:40:31,346 --> 00:40:35,642 No one was killed, but more than a thousand people were injured. 624 00:40:37,894 --> 00:40:40,564 Asteroids have struck Earth before. 625 00:40:40,731 --> 00:40:42,566 Some 65 million years ago... 626 00:40:42,941 --> 00:40:47,738 ...a monster 6 miles wide may have wiped out half the species on Earth. 627 00:40:47,904 --> 00:40:50,073 Remember the dinosaurs? 628 00:40:50,240 --> 00:40:53,452 A similar impact, or worse, could happen any time... 629 00:40:53,952 --> 00:40:57,331 ...and turn our blue marble into a lifeless rock. 630 00:40:59,541 --> 00:41:00,834 And the bottom line? 631 00:41:01,001 --> 00:41:03,962 Earth cannot sustain us forever. 632 00:41:04,755 --> 00:41:08,967 In a few billion years, our sun will expand as it begins to die... 633 00:41:10,844 --> 00:41:13,639 ...and our planet will be toast. 634 00:41:17,267 --> 00:41:18,477 But there's good news. 635 00:41:18,644 --> 00:41:19,978 Unlike the dinosaurs... 636 00:41:20,145 --> 00:41:22,397 MAN: Flight crew, close and lock your visors. Time to fly. 637 00:41:22,564 --> 00:41:24,232 NARRATOR: we can leave Earth. 638 00:41:24,399 --> 00:41:26,943 MAN: T-minus-10, nine... 639 00:41:27,110 --> 00:41:28,820 Ignition sequence start. 640 00:41:28,987 --> 00:41:33,950 Six, five, four, three, two, one. 641 00:41:34,826 --> 00:41:36,286 Zero. 642 00:41:40,332 --> 00:41:44,211 Zero and liftoff of space shuttle Atlantis. 643 00:41:44,378 --> 00:41:47,714 NARRATOR: Today, nearly 600 people have traveled to space. 644 00:41:49,549 --> 00:41:54,346 During the shuttle era, Marsha Ivins made the trip five times. 645 00:41:54,513 --> 00:42:00,310 In order to record all of this, um, we have created this, uh, wiring nightmare here. 646 00:42:00,477 --> 00:42:05,107 NARRATOR: At Kennedy Space Center Visitor Complex, she checks in on an old friend. 647 00:42:06,900 --> 00:42:11,822 IVINS: I look at Atlantis hanging here, it's a surreal kind of experience to think... 648 00:42:12,531 --> 00:42:14,491 ...I flew that into space. 649 00:42:14,658 --> 00:42:17,119 It's still something that I have a hard time believing. 650 00:42:17,285 --> 00:42:18,620 - Hi. - My name is Tanya. 651 00:42:18,787 --> 00:42:19,996 PHOTOGRAPHER: One, two, three. 652 00:42:20,163 --> 00:42:24,000 And it makes me feel good that people still have a wonder... 653 00:42:24,167 --> 00:42:27,796 ...and an amazement and a pure joy... 654 00:42:27,963 --> 00:42:31,967 ...for the fact that we did fly this vehicle into space. 655 00:42:32,509 --> 00:42:37,347 NARRATOR: For Marsha, each mission was as breathtaking as her first. 656 00:42:37,514 --> 00:42:39,599 IVINS I looked up overhead... 657 00:42:39,766 --> 00:42:45,981 ...and here was this black sky and this blue Earth. 658 00:42:46,148 --> 00:42:50,652 All hits you at that point, "I am not on the planet anymore." 659 00:42:51,027 --> 00:42:54,906 And every astronaut who has flown has come back and said the same thing. 660 00:42:55,073 --> 00:42:56,825 As you circle the Earth... 661 00:42:56,992 --> 00:43:02,706 ...you do not see natural borders and boundaries that separate the countries. 662 00:43:02,873 --> 00:43:08,086 And all of the wars and the angst and the strife that tear this planet apart... 663 00:43:08,253 --> 00:43:11,131 ...seem so insignificant from that view. 664 00:43:12,424 --> 00:43:13,633 NOLAN: To me... 665 00:43:14,176 --> 00:43:19,848 ...space travel, space exploration has always represented the ultimate frontier. 666 00:43:20,015 --> 00:43:23,894 It's of the absolute extremities of what human experience is... 667 00:43:24,060 --> 00:43:28,231 ...and it's all about trying to, in some way, define our place in the universe. 668 00:43:28,398 --> 00:43:32,068 MAN: Forty seconds away from the Apollo 11 liftoff. 669 00:43:32,235 --> 00:43:33,904 JONATHAN: I remember growing up as a kid... 670 00:43:34,070 --> 00:43:37,949 ...and we were both fascinated by this impulse to flight. 671 00:43:38,116 --> 00:43:44,289 This impulse to build unimaginable machines and use them to blast off into space. 672 00:43:45,290 --> 00:43:51,087 MAN: Having fired the imagination of a generation, pulls into port for the last time. 673 00:43:51,254 --> 00:43:54,007 NARRATOR: The space shuttles were retired in 2011... 674 00:43:54,174 --> 00:43:57,511 ...after traveling more than a half billion miles. 675 00:43:59,930 --> 00:44:03,141 Space exploration demands enormous resources. 676 00:44:03,308 --> 00:44:06,603 The kind that government agencies like NASA can marshal. 677 00:44:07,854 --> 00:44:10,649 Recently, some new players entered the fray. 678 00:44:11,691 --> 00:44:14,861 MUSK: I do think we're at the dawn of a new space era... 679 00:44:15,028 --> 00:44:17,614 ...and it's one where commercial companies play a stronger role. 680 00:44:17,781 --> 00:44:19,324 NASA'S not out of the picture. 681 00:44:19,491 --> 00:44:25,205 They're very much in the picture, but it's not all a NASA-designed system. 682 00:44:26,039 --> 00:44:31,086 NARRATOR: In 2002, Elon Musk started his own rocket company. 683 00:44:31,253 --> 00:44:34,297 A decade later, under contract to NASA... 684 00:44:34,464 --> 00:44:38,510 ...SpaceX became the first private company in history to carry supplies... 685 00:44:38,677 --> 00:44:41,137 ...to and from the International Space Station. 686 00:44:44,975 --> 00:44:48,687 Now SpaceX is tackling an even greater challenge. 687 00:44:48,854 --> 00:44:53,400 MUSK: I started SpaceX with the idea of trying to revolutionize space transport. 688 00:44:53,567 --> 00:44:57,988 And critical to that is full and rapid reusability of the rocket. 689 00:44:59,322 --> 00:45:02,701 The big issue with rocketry today is you get one use out of the rocket... 690 00:45:02,868 --> 00:45:07,497 ...and then it smashes down into the ocean or into the plains of Siberia, um... 691 00:45:07,664 --> 00:45:09,374 ...and you can't use it again. 692 00:45:10,959 --> 00:45:13,795 If you can, in fact, land the rocket safely... 693 00:45:13,962 --> 00:45:16,590 ...and then reuse it with a minimal amount of effort... 694 00:45:16,756 --> 00:45:22,304 ...then you can dramatically reduce the cost of space transport. 695 00:45:22,470 --> 00:45:27,684 NARRATOR: SpaceX is currently developing a fully and rapidly reusable launch system. 696 00:45:27,851 --> 00:45:30,645 And that will take Elon closer to a more ambitious goal: 697 00:45:31,605 --> 00:45:36,401 To help send crews to establish a colony on Mars. 698 00:45:37,110 --> 00:45:39,821 Not a mission for the fainthearted. 699 00:45:40,488 --> 00:45:42,073 MUSK: Anyone who wants to go to Mars... 700 00:45:42,240 --> 00:45:47,871 ...their desire for adventure would have to overcome their desire for comfort and safety. 701 00:45:48,872 --> 00:45:53,335 NARRATOR: The colony on Mars could be the next giant leap for humankind. 702 00:45:53,501 --> 00:45:56,630 NOLAN: It's such a fundamental idea when you think about it. 703 00:45:56,796 --> 00:46:00,467 It's just a decision that has to be made in terms of how you view the- 704 00:46:00,634 --> 00:46:02,886 The human race's place in the universe. 705 00:46:03,053 --> 00:46:09,100 We either stay here on Earth or we leave and we journey through the galaxy. 706 00:46:12,395 --> 00:46:15,190 NARRATOR: To create the look of the space technology in Interstellar... 707 00:46:15,357 --> 00:46:18,777 ...Christopher Nolan took a clear design approach. 708 00:46:18,944 --> 00:46:22,864 NOLAN: We didn't wanna have anything that felt purely decorative. 709 00:46:23,031 --> 00:46:26,785 We wanted to approach it from a more functional point of view... 710 00:46:26,952 --> 00:46:28,912 ...just be as convincing as possible... 711 00:46:29,079 --> 00:46:31,706 ...looking at the NASA technology that exists today... 712 00:46:31,873 --> 00:46:34,918 ...the International Space Station, these kind of things as our influences. 713 00:46:36,211 --> 00:46:40,256 NARRATOR: There's no telling how space technology Will evolve in the years to come. 714 00:46:41,216 --> 00:46:46,429 We may be decades away or longer from establishing a colony on Mars... 715 00:46:46,930 --> 00:46:50,183 ...or a permanent habitat in orbit around the Earth. 716 00:46:50,350 --> 00:46:53,561 But people around the world are dreaming of that next step. 717 00:46:56,231 --> 00:46:58,900 At a recent space conference... 718 00:46:59,067 --> 00:47:01,069 ...NASA and the National Space Society... 719 00:47:01,403 --> 00:47:05,365 ...handed out awards to dozens of forward-looking designs. 720 00:47:07,784 --> 00:47:10,996 A self-sustaining settlement for 20,000 people. 721 00:47:12,539 --> 00:47:16,459 A moon base that mines minerals from lunar soil. 722 00:47:17,002 --> 00:47:20,380 A fleet of robots that clean up space junk. 723 00:47:20,547 --> 00:47:23,008 But, of course, this is hard because we're burning fuel... 724 00:47:23,174 --> 00:47:26,553 NARRATOR: There's not a single PhD among the prize-Winning designers. 725 00:47:26,720 --> 00:47:28,888 [SINGING IN SPANISH] 726 00:47:30,140 --> 00:47:33,476 NARRATOR: These are middle and high school students from around the world. 727 00:47:33,643 --> 00:47:39,274 What first inspired me was the sky, the stars, the moon, the planets. 728 00:47:39,441 --> 00:47:44,529 Thinking about going to space is really exhilarating. 729 00:47:44,696 --> 00:47:48,825 I've always wanted to know, like, what's next? And for me, space is next. 730 00:47:48,992 --> 00:47:51,244 What we can do is beyond our imagination. 731 00:47:51,619 --> 00:47:57,709 For the survival of the human race, really, the only option is to go into space. 732 00:47:57,876 --> 00:48:01,588 It should be something that... A first step we should take as a world. 733 00:48:01,755 --> 00:48:05,133 NARRATOR: One of these kids may stand on Mars someday... 734 00:48:05,300 --> 00:48:07,510 ...or make a breakthrough in propulsion systems... 735 00:48:08,011 --> 00:48:10,555 ...or start a revolution in astrophysics. 736 00:48:11,931 --> 00:48:16,019 To inspire their kind of enthusiasm is the hope of the Interstellar team. 737 00:48:16,561 --> 00:48:19,022 THOMAS: I would love for kids to watch Interstellar... 738 00:48:19,189 --> 00:48:23,318 ...and get excited about possibilities of space travel and exploration. 739 00:48:23,651 --> 00:48:28,948 I would hope that this film introduces many people to science... 740 00:48:29,115 --> 00:48:32,869 ...who might not have gotten curious about this kind of science in any other way. 741 00:48:33,036 --> 00:48:36,706 I think it would be really thrilling if people got some sense from this film... 742 00:48:36,873 --> 00:48:39,501 ...that, uh, these ideas are worth thinking about. 743 00:48:42,212 --> 00:48:44,964 NARRATOR: The interplay between science and science fiction... 744 00:48:45,131 --> 00:48:47,759 ...springs from a deep-seated creative drive. 745 00:48:51,262 --> 00:48:52,597 To make sense of the unknown. 746 00:49:01,106 --> 00:49:02,690 To engineer new worlds. 747 00:49:07,779 --> 00:49:09,531 To dream up a better future. 748 00:49:10,782 --> 00:49:14,202 We'll find answers where we always have: 749 00:49:14,869 --> 00:49:17,455 Just beyond the next horizon.