1 00:00:04,905 --> 00:00:09,408 NARRATOR: It's a mysterious force that shapes our universe. 2 00:00:09,410 --> 00:00:11,910 It feels familiar, 3 00:00:11,912 --> 00:00:15,481 but it's far stranger than anyone ever imagined. 4 00:00:17,284 --> 00:00:21,787 And yet, one man's brilliant mind tamed it. 5 00:00:21,789 --> 00:00:24,590 Gravity. 6 00:00:24,592 --> 00:00:27,559 Using simple thought experiments, 7 00:00:27,561 --> 00:00:30,929 Albert Einstein made an astonishing discovery: 8 00:00:30,931 --> 00:00:35,634 time and space are shaped by matter. 9 00:00:35,636 --> 00:00:37,803 CLIFFORD JOHNSON: You get rid of this force of gravity, 10 00:00:37,805 --> 00:00:40,472 and instead, we have curvature of spacetime. 11 00:00:40,474 --> 00:00:43,042 JANNA LEVIN: Right now, the space around me 12 00:00:43,044 --> 00:00:45,177 is being squeezed and stretched. 13 00:00:45,179 --> 00:00:49,081 NARRATOR: He called it the "General Theory of Relativity." 14 00:00:49,083 --> 00:00:54,586 How did one person, working almost entirely alone, 15 00:00:54,588 --> 00:00:58,057 change everything we thought we knew about the universe? 16 00:00:58,059 --> 00:00:59,291 DAVID KAISER: Einstein is toiling 17 00:00:59,293 --> 00:01:01,927 as the world seems to fall apart. 18 00:01:01,929 --> 00:01:04,863 ROBBERT DIJKGRAAF: He was able with pure thought 19 00:01:04,865 --> 00:01:06,632 to solve the riddle of the universe. 20 00:01:06,634 --> 00:01:11,603 NARRATOR: "Inside Einstein's Mind," right now on NOVA. 21 00:01:26,253 --> 00:01:29,822 Major funding for NOVA is provided by the following... 22 00:01:31,292 --> 00:01:34,359 Shouldn't what makes each of us unique 23 00:01:34,361 --> 00:01:38,097 Supporting NOVA and promoting public understanding of science. 24 00:01:40,801 --> 00:01:43,802 And the Corporation for Public Broadcasting. 25 00:01:43,804 --> 00:01:45,304 And by PBS viewers like you. 26 00:01:45,306 --> 00:01:47,739 Thank you. 27 00:01:47,741 --> 00:01:49,741 Additional funding from Roger and Vicki Sant. 28 00:01:58,519 --> 00:02:00,819 NARRATOR: Gravity. 29 00:02:02,957 --> 00:02:09,862 The most familiar yet most mysterious of nature's forces. 30 00:02:09,864 --> 00:02:14,266 100 years ago, Albert Einstein made a mind-blowing discovery: 31 00:02:14,268 --> 00:02:17,236 what we feel as gravity 32 00:02:17,238 --> 00:02:23,108 is in fact the push and pull of space and time itself. 33 00:02:23,110 --> 00:02:26,945 He called his idea "general relativity." 34 00:02:26,947 --> 00:02:29,948 It is perhaps the most remarkable feat 35 00:02:29,950 --> 00:02:33,619 of thinking about nature to come from a single mind. 36 00:02:33,621 --> 00:02:35,387 CLIFFORD JOHNSON: General relativity 37 00:02:35,389 --> 00:02:37,890 is undoubtedly one of the greatest scientific theories 38 00:02:37,892 --> 00:02:39,858 ever conceived. 39 00:02:39,860 --> 00:02:41,727 It's a theory of space, time, and gravity. 40 00:02:44,098 --> 00:02:45,831 JANNA LEVIN: One mathematical sentence, 41 00:02:45,833 --> 00:02:47,766 and from it, you can derive 42 00:02:47,768 --> 00:02:50,302 the understanding of the entire universe 43 00:02:50,304 --> 00:02:53,205 on the largest scales, and that is beautiful. 44 00:02:55,776 --> 00:02:59,778 NARRATOR: Only now, a century after it was first proposed, 45 00:02:59,780 --> 00:03:01,313 do we have the technology 46 00:03:01,315 --> 00:03:05,184 to explore the extremes of Einstein's great theory. 47 00:03:06,820 --> 00:03:10,255 Supermassive black holes at the center of galaxies. 48 00:03:10,257 --> 00:03:16,295 Waves of gravity that distort space and time. 49 00:03:16,297 --> 00:03:19,998 The evolution of our entire universe. 50 00:03:20,000 --> 00:03:23,902 How did a concept that explains so much 51 00:03:23,904 --> 00:03:27,072 come from the mind of one man? 52 00:03:27,074 --> 00:03:30,008 JOHN NORTON: Einstein had a magical talent. 53 00:03:30,010 --> 00:03:32,411 He could take a hard, physical problem 54 00:03:32,413 --> 00:03:36,014 and boil it down to a powerful visual image, 55 00:03:36,016 --> 00:03:37,516 a thought experiment. 56 00:03:37,518 --> 00:03:39,351 SEAN CARROLL: Suddenly he realizes, 57 00:03:39,353 --> 00:03:41,220 "This is how the world works. 58 00:03:41,222 --> 00:03:45,657 All this abstract nonsense is the correct theory of reality." 59 00:03:45,659 --> 00:03:48,093 NARRATOR: To gain an insight into Einstein's mind 60 00:03:48,095 --> 00:03:51,730 and the true wonder of general relativity, 61 00:03:51,732 --> 00:03:55,300 we need to trace the crucial thought experiments 62 00:03:55,302 --> 00:03:57,569 that led to his great breakthrough. 63 00:03:57,571 --> 00:03:59,972 The seeds for his ideas 64 00:03:59,974 --> 00:04:02,808 were planted when he was just a child. 65 00:04:13,020 --> 00:04:15,887 Einstein grew up in a small house in Munich, 66 00:04:15,889 --> 00:04:18,390 in southern Germany. 67 00:04:18,392 --> 00:04:21,793 His unique personality was evident early on. 68 00:04:24,732 --> 00:04:26,999 WALTER ISAACSON: Like many great innovators, 69 00:04:27,001 --> 00:04:29,301 Einstein was a rebel, a loner, 70 00:04:29,303 --> 00:04:31,470 but deeply curious. 71 00:04:31,472 --> 00:04:34,339 He was slow in learning to speak as a child, 72 00:04:34,341 --> 00:04:37,042 so slow that his parents consulted a doctor, 73 00:04:37,044 --> 00:04:39,177 but he later said that that's maybe why he thought 74 00:04:39,179 --> 00:04:42,114 in visual thought experiments. 75 00:04:42,116 --> 00:04:46,385 His sister remembers him building little card towers 76 00:04:46,387 --> 00:04:48,487 using playing cards. 77 00:04:48,489 --> 00:04:52,858 He was a daydreamer, but he was deeply persistent. 78 00:04:55,462 --> 00:04:57,429 NARRATOR: Einstein's father, Hermann, 79 00:04:57,431 --> 00:05:00,165 manufactured electrical equipment. 80 00:05:00,167 --> 00:05:03,702 He nurtured his son's interest in science. 81 00:05:03,704 --> 00:05:08,040 On one occasion, he brought him a compass. 82 00:05:08,042 --> 00:05:10,442 ISAACSON: Now, you and I maybe remember getting a compass 83 00:05:10,444 --> 00:05:11,943 when we were kids, and we were like, 84 00:05:11,945 --> 00:05:14,212 "Oh look, the needle twitches and points north," 85 00:05:14,214 --> 00:05:15,480 but then we're on to something else, 86 00:05:15,482 --> 00:05:17,582 like, "Oh look, there's a dead squirrel." 87 00:05:17,584 --> 00:05:19,751 But for Einstein, after getting that compass, 88 00:05:19,753 --> 00:05:22,654 he developed a lifelong devotion 89 00:05:22,656 --> 00:05:25,824 to understanding how things can be forced to move 90 00:05:25,826 --> 00:05:27,392 even though nothing's touching them. 91 00:05:32,466 --> 00:05:35,901 NARRATOR: The young Einstein became gripped by a desire 92 00:05:35,903 --> 00:05:39,504 to understand the underlying laws of nature. 93 00:05:39,506 --> 00:05:41,673 He developed a unique way 94 00:05:41,675 --> 00:05:44,509 of thinking about the physical world 95 00:05:44,511 --> 00:05:46,678 inspired by his favorite book. 96 00:05:46,680 --> 00:05:48,113 ISAACSON: The book Einstein loved 97 00:05:48,115 --> 00:05:49,481 told little stories, 98 00:05:49,483 --> 00:05:51,149 like what it'd be like to travel through space 99 00:05:51,151 --> 00:05:52,718 or go through an electrical wire. 100 00:05:52,720 --> 00:05:57,155 And it made Einstein think visually. 101 00:05:57,157 --> 00:06:00,525 NARRATOR: These imagined situations 102 00:06:00,527 --> 00:06:04,029 that we often call "thought experiments" 103 00:06:04,031 --> 00:06:06,898 became a defining feature of Einstein's thinking. 104 00:06:06,900 --> 00:06:08,934 DAVID KAISER: One of the critical thought experiments 105 00:06:08,936 --> 00:06:10,369 that Einstein began to play with 106 00:06:10,371 --> 00:06:12,137 very young, around the age of 16, 107 00:06:12,139 --> 00:06:13,939 was trying to imagine what would happen 108 00:06:13,941 --> 00:06:16,007 if he could catch up with a light wave. 109 00:06:16,009 --> 00:06:19,277 It's one thing to imagine a light wave zooming past him 110 00:06:19,279 --> 00:06:21,213 at some seemingly impossible speed, 111 00:06:21,215 --> 00:06:25,417 but what if he could somehow just propel himself 112 00:06:25,419 --> 00:06:26,752 really quickly? 113 00:06:26,754 --> 00:06:27,986 What would it look like 114 00:06:27,988 --> 00:06:29,488 if he could catch up with that light wave? 115 00:06:29,490 --> 00:06:31,590 What would he see? 116 00:06:36,730 --> 00:06:40,098 ISAACSON: He said it caused him to walk around in such anxiety, 117 00:06:40,100 --> 00:06:41,566 his palms would sweat. 118 00:06:41,568 --> 00:06:43,168 Now, you and I may remember 119 00:06:43,170 --> 00:06:45,771 what was causing our palms to sweat at age 16, 120 00:06:45,773 --> 00:06:47,506 and it was not a light beam. 121 00:06:47,508 --> 00:06:49,408 But that's why he's Einstein. 122 00:06:55,048 --> 00:06:58,750 NARRATOR: This dream-like thought about the nature of light 123 00:06:58,752 --> 00:07:02,754 was Einstein's first step on the path to his great theory. 124 00:07:05,559 --> 00:07:09,861 It stayed with him throughout his time at school and college. 125 00:07:09,863 --> 00:07:11,797 KAISER: He was extremely gifted 126 00:07:11,799 --> 00:07:13,432 in science and math as a young person 127 00:07:13,434 --> 00:07:15,567 and very bad at other classes, 128 00:07:15,569 --> 00:07:17,068 mostly because he kept cutting class 129 00:07:17,070 --> 00:07:18,570 and being very rude to his teachers. 130 00:07:18,572 --> 00:07:21,072 Many teachers from his high school days on 131 00:07:21,074 --> 00:07:23,108 were convinced he'd never amount to anything. 132 00:07:23,110 --> 00:07:26,745 He was a discipline problem, and he was bad news. 133 00:07:26,747 --> 00:07:29,481 ISAACSON: He applies to the second best university in Zurich, 134 00:07:29,483 --> 00:07:32,417 the Zurich Polytech, and gets rejected. 135 00:07:32,419 --> 00:07:34,186 I'd love to meet the admissions director 136 00:07:34,188 --> 00:07:35,620 who rejected Albert Einstein. 137 00:07:35,622 --> 00:07:39,257 But eventually he gets in, and he does moderately well, 138 00:07:39,259 --> 00:07:42,093 but not good enough to get a teaching fellowship. 139 00:07:42,095 --> 00:07:45,130 And so he ends up at the Bern Swiss patent office 140 00:07:45,132 --> 00:07:46,665 as a third class examiner. 141 00:07:50,170 --> 00:07:52,370 NARRATOR: Undaunted by his university results, 142 00:07:52,372 --> 00:07:57,275 Einstein started work at the patent office in 1902, 143 00:07:57,277 --> 00:07:58,944 age 23. 144 00:08:00,714 --> 00:08:05,250 Here, his job was to assess the originality of new devices. 145 00:08:05,252 --> 00:08:07,319 KAISER: He was immersed 146 00:08:07,321 --> 00:08:10,021 in the kinds of technical details 147 00:08:10,023 --> 00:08:12,224 that he'd been fascinated by as a very young kid. 148 00:08:12,226 --> 00:08:15,994 And here he was, sitting in the kind of wave 149 00:08:15,996 --> 00:08:17,329 of the modern age. 150 00:08:17,331 --> 00:08:19,898 This was the era of electrification. 151 00:08:19,900 --> 00:08:24,069 So all the latest clever ideas for switching technology, 152 00:08:24,071 --> 00:08:27,105 for coordinating clocks in particular, 153 00:08:27,107 --> 00:08:29,441 those were all passing through his office. 154 00:08:29,443 --> 00:08:33,678 NARRATOR: Time zones had recently been introduced in central Europe, 155 00:08:33,680 --> 00:08:37,182 and accurately synchronizing clocks 156 00:08:37,184 --> 00:08:39,584 was a major challenge of the day. 157 00:08:39,586 --> 00:08:44,189 Switzerland was a world leader in time technology. 158 00:08:44,191 --> 00:08:47,225 Dozens of patents to link clocks 159 00:08:47,227 --> 00:08:49,461 passed through Einstein's office. 160 00:08:49,463 --> 00:08:51,796 ISAACSON: He could whip through these patent applications, 161 00:08:51,798 --> 00:08:55,100 and then out of his drawer, he'd pull his physics notes, 162 00:08:55,102 --> 00:08:57,335 and his boss was very indulgent 163 00:08:57,337 --> 00:08:59,337 and would sort of turn a blind eye 164 00:08:59,339 --> 00:09:03,375 as Einstein was doing his theories in his spare time. 165 00:09:03,377 --> 00:09:05,143 SIMON SCHAFFER: It's really important to remember that 166 00:09:05,145 --> 00:09:09,047 theoretical physics was new when Einstein was a young man. 167 00:09:09,049 --> 00:09:13,985 You could do quite a lot of this work by reading 168 00:09:13,987 --> 00:09:16,321 a relatively small number of science journals 169 00:09:16,323 --> 00:09:19,558 and making the calculations yourself. 170 00:09:21,728 --> 00:09:24,396 Einstein's world in 1905 171 00:09:24,398 --> 00:09:29,134 was dominated by two kinds of physics. 172 00:09:29,136 --> 00:09:33,572 One was about 200 years old, 173 00:09:33,574 --> 00:09:37,709 founded by Isaac Newton, a British natural philosopher. 174 00:09:37,711 --> 00:09:43,915 For Newton, all there is in the world is matter moving. 175 00:09:43,917 --> 00:09:46,451 NARRATOR: Newton showed that the motion 176 00:09:46,453 --> 00:09:49,821 of falling apples and orbiting planets 177 00:09:49,823 --> 00:09:52,157 are governed by the same force: 178 00:09:52,159 --> 00:09:55,360 gravity. 179 00:09:55,362 --> 00:09:59,965 His equations are so effective, we still use them today 180 00:09:59,967 --> 00:10:03,301 to send probes to the farthest reaches of the solar system. 181 00:10:05,572 --> 00:10:08,273 The other important theory of Einstein's day 182 00:10:08,275 --> 00:10:12,177 covered electricity and magnetism. 183 00:10:12,179 --> 00:10:16,448 That branch of physics had been revolutionized in 1865 184 00:10:16,450 --> 00:10:20,018 by the Scottish physicist James Clerk Maxwell. 185 00:10:20,020 --> 00:10:23,755 Maxwell's theory describes light 186 00:10:23,757 --> 00:10:30,195 as an electromagnetic wave that travels at a fixed speed. 187 00:10:34,735 --> 00:10:40,572 In Newton's world, the speed of light is not fixed. 188 00:10:42,709 --> 00:10:45,677 SCHAFFER: Einstein could see that there's a contradiction 189 00:10:45,679 --> 00:10:48,013 between Newton and Maxwell. 190 00:10:48,015 --> 00:10:50,448 They just don't fit together. 191 00:10:50,450 --> 00:10:54,219 And one of the things Einstein hated-- hated-- 192 00:10:54,221 --> 00:10:56,154 was contradiction. 193 00:10:56,156 --> 00:10:59,658 If there's one kind of physics that says this 194 00:10:59,660 --> 00:11:02,327 and another kind of physics that says that 195 00:11:02,329 --> 00:11:03,962 and they're different, 196 00:11:03,964 --> 00:11:07,499 that's a sign that something's gone wrong and it needs fixing. 197 00:11:13,607 --> 00:11:16,474 NARRATOR: For months, Einstein wrestles 198 00:11:16,476 --> 00:11:18,009 with the problem. 199 00:11:18,011 --> 00:11:20,011 Eventually, 200 00:11:20,013 --> 00:11:21,880 to resolve this contradiction, 201 00:11:21,882 --> 00:11:26,885 he focuses on a key element of speed: time. 202 00:11:26,887 --> 00:11:29,287 ISAACSON: He realized that 203 00:11:29,289 --> 00:11:31,256 any statement about time 204 00:11:31,258 --> 00:11:34,159 is simply a question about what is simultaneous. 205 00:11:34,161 --> 00:11:37,095 For example, if you say the train arrives at 7:00, 206 00:11:37,097 --> 00:11:39,497 that simply means that it gets to the platform 207 00:11:39,499 --> 00:11:43,134 simultaneous with the clock going to 7:00. 208 00:11:43,136 --> 00:11:45,670 NARRATOR: In a brilliant thought experiment, 209 00:11:45,672 --> 00:11:50,442 he questions what "simultaneous" actually means 210 00:11:50,444 --> 00:11:52,010 and sees that the flow of time 211 00:11:52,012 --> 00:11:56,181 is different for an observer that is moving 212 00:11:56,183 --> 00:11:58,450 versus one that is standing still. 213 00:12:07,894 --> 00:12:12,330 He imagines a man standing on a railway platform. 214 00:12:12,332 --> 00:12:16,434 Two bolts of lightning strike on either side of him. 215 00:12:16,436 --> 00:12:19,304 (lightning strike) 216 00:12:19,306 --> 00:12:22,807 The man is standing exactly halfway between them 217 00:12:22,809 --> 00:12:26,411 and the light from each strike reaches his eyes 218 00:12:26,413 --> 00:12:28,980 at exactly same moment. 219 00:12:28,982 --> 00:12:32,450 For him, the two strikes are simultaneous. 220 00:12:32,452 --> 00:12:35,153 (thunder rumbling) 221 00:12:41,294 --> 00:12:47,198 Then Einstein imagines a woman on a fast-moving train, 222 00:12:47,200 --> 00:12:50,802 Traveling at close to the speed of light, 223 00:12:50,804 --> 00:12:53,738 what would she see? 224 00:12:57,878 --> 00:13:01,112 As the light travels out from the strikes, 225 00:13:01,114 --> 00:13:07,018 the train is moving towards one and away from the other. 226 00:13:07,020 --> 00:13:11,656 Light from the front strike reaches her eyes first. 227 00:13:11,658 --> 00:13:15,560 For the woman on the train, 228 00:13:15,562 --> 00:13:18,129 time elapses between the two strikes. 229 00:13:18,131 --> 00:13:21,232 (thunder rumbling) 230 00:13:21,234 --> 00:13:23,034 For the man on the platform, 231 00:13:23,036 --> 00:13:24,903 there is no time between the strikes. 232 00:13:24,905 --> 00:13:26,538 (thunder rumbling) 233 00:13:31,077 --> 00:13:37,315 This simple thought has mind-blowing significance. 234 00:13:37,317 --> 00:13:43,621 Simultaneity, and the flow of time itself, 235 00:13:43,623 --> 00:13:45,390 depends on how you're moving. 236 00:13:48,495 --> 00:13:50,328 If there's no such thing as simultaneity, 237 00:13:50,330 --> 00:13:52,330 then there's no such thing as absolute time everywhere 238 00:13:52,332 --> 00:13:55,133 throughout the universe, and Isaac Newton was wrong. 239 00:13:57,237 --> 00:14:02,774 NARRATOR: This concept that time, and space as well, are relative 240 00:14:02,776 --> 00:14:06,344 became known as special relativity. 241 00:14:06,346 --> 00:14:09,914 It led to remarkable results, 242 00:14:09,916 --> 00:14:15,887 such as the famous equation relating energy to mass. 243 00:14:15,889 --> 00:14:17,956 Einstein published this article in 1905 244 00:14:17,958 --> 00:14:19,357 to exactly no acclaim. 245 00:14:19,359 --> 00:14:20,592 Most people ignored it. 246 00:14:20,594 --> 00:14:23,728 This was not setting the world on fire. 247 00:14:23,730 --> 00:14:27,332 Two years go by before a very eminent physicist, 248 00:14:27,334 --> 00:14:29,801 Johannes Stark, invites Einstein 249 00:14:29,803 --> 00:14:32,003 to write a review article on Einstein's own work, 250 00:14:32,005 --> 00:14:33,705 precisely because no one was paying attention. 251 00:14:33,707 --> 00:14:37,542 And he begins thinking about ways to generalize 252 00:14:37,544 --> 00:14:39,344 and to push his own results from 1905. 253 00:14:39,346 --> 00:14:41,880 What if he considers not only a train 254 00:14:41,882 --> 00:14:44,182 moving at a fixed speed past the platform? 255 00:14:44,184 --> 00:14:46,251 What if that train begins to speed up or slow down? 256 00:14:46,253 --> 00:14:48,019 What if there's acceleration? 257 00:14:48,021 --> 00:14:52,490 NARRATOR: Adding acceleration to the equations was his first task. 258 00:14:52,492 --> 00:14:58,363 Then there was that mysterious Newtonian force of gravity 259 00:14:58,365 --> 00:15:00,164 to contend with. 260 00:15:00,166 --> 00:15:01,933 In Newton's theory, 261 00:15:01,935 --> 00:15:05,536 gravity is a force that acts instantaneously. 262 00:15:05,538 --> 00:15:08,006 But special relativity says that's impossible-- 263 00:15:08,008 --> 00:15:12,944 nothing can travel faster than light. 264 00:15:12,946 --> 00:15:14,812 ELEANOR KNOX: What Newton's theory tells you is that 265 00:15:14,814 --> 00:15:17,482 suppose the sun were to disappear, 266 00:15:17,484 --> 00:15:20,551 the orbit of the earth should change at that very moment. 267 00:15:20,553 --> 00:15:22,787 But the notion of "at that very moment" 268 00:15:22,789 --> 00:15:25,890 in two different places is exactly one of these notions 269 00:15:25,892 --> 00:15:27,425 that special relativity has told you 270 00:15:27,427 --> 00:15:28,826 isn't a good physics notion. 271 00:15:28,828 --> 00:15:34,132 So you've now got this challenge of trying to work out 272 00:15:34,134 --> 00:15:36,200 how to take the success of Newton's theory of gravity 273 00:15:36,202 --> 00:15:39,304 but fit it into this new special relativistic picture. 274 00:15:39,306 --> 00:15:43,675 NARRATOR: It was only when Einstein began to understand the link 275 00:15:43,677 --> 00:15:46,010 between gravity and acceleration 276 00:15:46,012 --> 00:15:50,281 that things began to fall into place. 277 00:15:52,185 --> 00:15:54,686 We all know that when we are accelerated, 278 00:15:54,688 --> 00:15:57,622 and of course now we have cars and airplanes 279 00:15:57,624 --> 00:16:01,626 to give us the physical feeling, 280 00:16:01,628 --> 00:16:03,962 if you're in an airplane and it's taking off, 281 00:16:03,964 --> 00:16:05,763 you are pushed back in your chair, 282 00:16:05,765 --> 00:16:07,966 you feel actually kind of a force pushing you back, 283 00:16:07,968 --> 00:16:10,935 which feels very similar to the force of gravity. 284 00:16:10,937 --> 00:16:13,604 But you need the brilliance of Einstein 285 00:16:13,606 --> 00:16:16,607 to explain why they are related. 286 00:16:17,978 --> 00:16:20,511 NARRATOR: Suddenly, he hits upon what he describes as 287 00:16:20,513 --> 00:16:24,582 the happiest thought of his life. 288 00:16:24,584 --> 00:16:28,252 If gravity and acceleration feel the same, 289 00:16:28,254 --> 00:16:32,957 perhaps they are the same. 290 00:16:32,959 --> 00:16:36,494 Again, he examines the idea 291 00:16:36,496 --> 00:16:39,597 in a beautiful thought experiment. 292 00:16:39,599 --> 00:16:42,066 He imagines a man in a box 293 00:16:42,068 --> 00:16:45,570 floating weightlessly in a distant region of space 294 00:16:45,572 --> 00:16:46,904 in zero gravity. 295 00:16:50,143 --> 00:16:51,909 Suddenly, the man stops floating 296 00:16:51,911 --> 00:16:57,348 and accelerates downward until he's standing in the box. 297 00:16:57,350 --> 00:17:00,451 What has happened? 298 00:17:02,555 --> 00:17:05,390 Either the box is now close to a planet 299 00:17:05,392 --> 00:17:11,829 and the force of gravity has pulled the man to the floor, 300 00:17:11,831 --> 00:17:15,033 or someone has attached a rope 301 00:17:15,035 --> 00:17:18,336 and the box is now being pulled continuously 302 00:17:18,338 --> 00:17:20,705 and accelerated upwards. 303 00:17:24,477 --> 00:17:27,612 So which is it? 304 00:17:27,614 --> 00:17:30,348 Gravity? 305 00:17:30,350 --> 00:17:33,618 Or acceleration? 306 00:17:33,620 --> 00:17:37,321 Without being able to see outside, 307 00:17:37,323 --> 00:17:41,359 the man can't tell what's causing his fall to the floor. 308 00:17:41,361 --> 00:17:43,327 CARROLL: Einstein realized 309 00:17:43,329 --> 00:17:46,064 there is no way to tell the difference 310 00:17:46,066 --> 00:17:48,066 between sitting in a gravitational field 311 00:17:48,068 --> 00:17:49,567 and being accelerated. 312 00:17:49,569 --> 00:17:51,936 These are equivalent situations 313 00:17:51,938 --> 00:17:54,272 JOHNSON: The fact that these two effects are the same, 314 00:17:54,274 --> 00:17:55,807 give the same result, 315 00:17:55,809 --> 00:17:58,443 means that gravity is acceleration. 316 00:17:58,445 --> 00:18:00,078 It's not just like acceleration; 317 00:18:00,080 --> 00:18:02,346 it's the same thing. 318 00:18:02,348 --> 00:18:06,584 NARRATOR: It's a big breakthrough. 319 00:18:06,586 --> 00:18:11,689 Einstein's theory of special relativity worked 320 00:18:11,691 --> 00:18:15,560 for motion at a constant speed. 321 00:18:15,562 --> 00:18:18,162 By extending his ideas to acceleration, 322 00:18:18,164 --> 00:18:22,100 he could begin to formulate a new theory of gravity. 323 00:18:38,051 --> 00:18:43,054 In 1912, Einstein is living in Zurich with his wife Mileva 324 00:18:43,056 --> 00:18:45,490 and two young sons, Hans and Eduard. 325 00:18:45,492 --> 00:18:49,927 The academic world had realized the importance 326 00:18:49,929 --> 00:18:53,898 of special relativity, and his career had taken off. 327 00:18:53,900 --> 00:18:55,566 He's now a professor 328 00:18:55,568 --> 00:18:58,136 at the esteemed Swiss Federal Institute of Technology, 329 00:18:58,138 --> 00:19:04,308 but spends as much time as possible working on his theory. 330 00:19:04,310 --> 00:19:06,410 He needs mathematics 331 00:19:06,412 --> 00:19:10,348 that describes how objects move in space and time 332 00:19:10,350 --> 00:19:14,051 and soon realizes that the best tool for the job 333 00:19:14,053 --> 00:19:20,324 is a strange but powerful concept called "spacetime." 334 00:19:20,326 --> 00:19:22,326 LEVIN: If I think of space, 335 00:19:22,328 --> 00:19:25,630 I know that I can find anything if I know where it is 336 00:19:25,632 --> 00:19:29,300 north-south, east-west, and up-down, three points. 337 00:19:29,302 --> 00:19:31,035 But that doesn't mean I can find it, 338 00:19:31,037 --> 00:19:33,204 because I also have to know where it is in time. 339 00:19:33,206 --> 00:19:35,006 And so if we start to think, 340 00:19:35,008 --> 00:19:38,109 to know everything about an event in the universe, 341 00:19:38,111 --> 00:19:41,078 I have to know not just its spatial coordinates, 342 00:19:41,080 --> 00:19:43,080 but also its time coordinate. 343 00:19:43,082 --> 00:19:46,050 I can begin to think about where it is in spacetime. 344 00:19:48,755 --> 00:19:51,989 NARRATOR: Imagine a camera filming an action, 345 00:19:51,991 --> 00:19:58,963 capturing each moment in time as a single frame. 346 00:20:06,172 --> 00:20:09,307 DIJKGRAAF: Einstein basically tells us, "Think of the movie reel." 347 00:20:09,309 --> 00:20:14,478 So you have all these little pictures. 348 00:20:14,480 --> 00:20:16,914 Now, cut them apart one by one 349 00:20:16,916 --> 00:20:18,416 and stack them on top of each other, 350 00:20:18,418 --> 00:20:21,352 you get this pile. 351 00:20:21,354 --> 00:20:24,755 And if you go up in the pile, you go up in time. 352 00:20:24,757 --> 00:20:29,594 And now kind of glue them all together into one big block, 353 00:20:29,596 --> 00:20:35,099 and that block has both space and time, 354 00:20:35,101 --> 00:20:39,470 and that's the spacetime continuum. 355 00:20:39,472 --> 00:20:43,207 It's almost looking at a movie not frame by frame, 356 00:20:43,209 --> 00:20:45,610 but seeing the whole movie at once. 357 00:20:45,612 --> 00:20:49,213 They would now be kind of two strands 358 00:20:49,215 --> 00:20:51,949 going up in space and time, 359 00:20:51,951 --> 00:20:55,253 and they would be kind of spaghetti strands. 360 00:20:55,255 --> 00:20:58,189 In fact, we all are spaghetti strands 361 00:20:58,191 --> 00:21:00,291 moving in this spacetime. 362 00:21:04,097 --> 00:21:08,933 NARRATOR: Einstein feels that spacetime is the natural arena 363 00:21:08,935 --> 00:21:11,969 in which his theory of relativity should play out. 364 00:21:11,971 --> 00:21:17,675 But now he needs sophisticated mathematics. 365 00:21:17,677 --> 00:21:20,144 By your standard or mine, Einstein was good at math. 366 00:21:20,146 --> 00:21:21,412 He was Einstein. 367 00:21:21,414 --> 00:21:23,881 But he was not really a mathematician per se. 368 00:21:23,883 --> 00:21:26,217 He didn't prove theorems, he didn't pore over math books. 369 00:21:26,219 --> 00:21:27,351 He was a physicist. 370 00:21:27,353 --> 00:21:28,819 He did thought experiments. 371 00:21:28,821 --> 00:21:31,489 He thought of very tangible, concrete situations 372 00:21:31,491 --> 00:21:32,923 and what would happen. 373 00:21:32,925 --> 00:21:35,459 So when it came time for him to really bear down 374 00:21:35,461 --> 00:21:37,728 to the absolute cutting edge mathematics of his day, 375 00:21:37,730 --> 00:21:39,530 he required help. 376 00:21:39,532 --> 00:21:45,936 NARRATOR: At university, Einstein had skipped the geometry classes, 377 00:21:45,938 --> 00:21:50,474 letting his friend Marcel Grossman take notes for him. 378 00:21:50,476 --> 00:21:53,177 Grossman had excelled in geometry 379 00:21:53,179 --> 00:21:56,647 and was now chairman of the math department. 380 00:21:56,649 --> 00:22:01,319 He suggests Einstein uses advanced mathematics 381 00:22:01,321 --> 00:22:06,624 in which the shape of space and time could be curved. 382 00:22:06,626 --> 00:22:08,926 CARROLL: Because spacetime has a geometry, 383 00:22:08,928 --> 00:22:11,195 he thinks to himself, 384 00:22:11,197 --> 00:22:13,597 "Well, maybe it's the actual shape of spacetime itself 385 00:22:13,599 --> 00:22:15,366 that is giving rise to gravity." 386 00:22:15,368 --> 00:22:24,542 NARRATOR: After months of work, Einstein has an extraordinary idea. 387 00:22:24,544 --> 00:22:31,015 "What if spacetime is shaped by matter, 388 00:22:31,017 --> 00:22:33,984 and that's what we feel as gravity?" 389 00:22:33,986 --> 00:22:38,322 JOHNSON: In struggling to figure out what causes gravity then, 390 00:22:38,324 --> 00:22:40,691 Einstein has this great insight. 391 00:22:40,693 --> 00:22:42,526 It is simply that a mass 392 00:22:42,528 --> 00:22:45,830 distorts the shape of spacetime around it. 393 00:22:45,832 --> 00:22:49,166 So you get rid of this force of gravity, 394 00:22:49,168 --> 00:22:53,537 and instead we have curvature of spacetime. 395 00:22:53,539 --> 00:22:55,139 In Einstein's universe then, 396 00:22:55,141 --> 00:22:57,875 if space were empty, it would be flat. 397 00:22:57,877 --> 00:22:59,210 There'd be nothing going on. 398 00:22:59,212 --> 00:23:01,345 But as soon as you put objects down, 399 00:23:01,347 --> 00:23:04,615 they warp the space and time around them, 400 00:23:04,617 --> 00:23:08,285 and that causes a deviation of the geometry 401 00:23:08,287 --> 00:23:11,088 so that now things start moving. 402 00:23:14,494 --> 00:23:17,828 DIJKGRAAF: Everything wants to move as simple as possible 403 00:23:17,830 --> 00:23:20,531 through space and time. 404 00:23:20,533 --> 00:23:26,103 But Einstein tells us that mass sculpts space and time, 405 00:23:26,105 --> 00:23:29,206 and it's the curved motion through this sculpture 406 00:23:29,208 --> 00:23:30,841 that's the force of gravity. 407 00:23:33,513 --> 00:23:35,079 KNOX: We have this feeling that 408 00:23:35,081 --> 00:23:37,481 the reason I can feel pressure on the soles of my feet, 409 00:23:37,483 --> 00:23:39,717 that the reason things are going to drop when I throw them, 410 00:23:39,719 --> 00:23:41,051 are because there's a force 411 00:23:41,053 --> 00:23:43,287 attracting us down to the center of the earth. 412 00:23:43,289 --> 00:23:46,390 What general relativity tells you is that's not the right way 413 00:23:46,392 --> 00:23:48,025 to think about what's going on there. 414 00:23:48,027 --> 00:23:54,064 What's really going on is that your natural path in spacetime 415 00:23:54,066 --> 00:23:55,933 would take you to the center of the earth, 416 00:23:55,935 --> 00:23:58,002 and what's actually happening is the floor is getting in the way, 417 00:23:58,004 --> 00:23:59,737 it's pushing you upwards. 418 00:23:59,739 --> 00:24:04,508 CARROLL: When we look at it, we go, "Ah, the force of gravity" 419 00:24:04,510 --> 00:24:07,077 But Einstein says, "No, no, no, the curvature of spacetime." 420 00:24:11,984 --> 00:24:16,353 NARRATOR: It's a stunning insight. 421 00:24:16,355 --> 00:24:20,891 Just as an ant might feel forces pulling it left and right 422 00:24:20,893 --> 00:24:22,993 as it walks over crumpled paper 423 00:24:22,995 --> 00:24:27,264 when it's simply the shape of a surface dictating its path, 424 00:24:27,266 --> 00:24:31,635 Einstein saw that what we feel as the force of gravity 425 00:24:31,637 --> 00:24:36,707 is in fact the shape of the spacetime we're moving through. 426 00:24:40,780 --> 00:24:44,081 Einstein now has everything he needs 427 00:24:44,083 --> 00:24:47,318 to formulate his final theory of gravity. 428 00:24:47,320 --> 00:24:51,055 But he makes a critical mistake. 429 00:24:51,057 --> 00:24:54,024 He misinterprets one of his equations, 430 00:24:54,026 --> 00:24:56,093 and unaware of his error, 431 00:24:56,095 --> 00:25:00,531 continues working on incorrect ideas. 432 00:25:00,533 --> 00:25:03,534 NORTON: The point at which Einstein is going to give 433 00:25:03,536 --> 00:25:05,469 the most essential equations of the theory, 434 00:25:05,471 --> 00:25:07,771 Einstein considers something like them 435 00:25:07,773 --> 00:25:10,341 and then says, "Ah, but these don't work," 436 00:25:10,343 --> 00:25:12,076 and then writes down the wrong equations. 437 00:25:16,816 --> 00:25:21,852 What follows are alternations of confidence and despair 438 00:25:21,854 --> 00:25:24,522 as he convinces himself that everything was fine 439 00:25:24,524 --> 00:25:26,524 with this theory, and then he realizes 440 00:25:26,526 --> 00:25:28,459 that things aren't so good with the theory. 441 00:25:32,298 --> 00:25:36,200 It is a long, dark period for Einstein 442 00:25:36,202 --> 00:25:38,402 as he struggles to reconcile himself 443 00:25:38,404 --> 00:25:41,605 with a theory that is just not working. 444 00:25:46,245 --> 00:25:50,214 NARRATOR: Two years later, Einstein is in Berlin. 445 00:25:50,216 --> 00:25:53,584 At just 36 years old, he has one of the most 446 00:25:53,586 --> 00:25:56,620 prestigious positions in physics. 447 00:25:56,622 --> 00:25:59,657 But he is still struggling with his theory. 448 00:26:06,832 --> 00:26:10,267 ISAACSON: By 1915, he'd reached the pinnacle of the profession. 449 00:26:10,269 --> 00:26:12,269 He's in the Prussian Academy 450 00:26:12,271 --> 00:26:14,338 and a professor at the University of Berlin. 451 00:26:14,340 --> 00:26:16,307 But his marriage is falling apart, 452 00:26:16,309 --> 00:26:19,577 his wife and his two kids have moved back to Switzerland, 453 00:26:19,579 --> 00:26:22,746 so he's pacing around almost all alone 454 00:26:22,748 --> 00:26:24,315 in this apartment in Berlin. 455 00:26:26,652 --> 00:26:28,819 NARRATOR: And now he has a competitor. 456 00:26:32,525 --> 00:26:35,292 Einstein had enthusiastically shared his ideas 457 00:26:35,294 --> 00:26:38,062 with the brilliant mathematician David Hilbert. 458 00:26:38,064 --> 00:26:41,398 Hilbert was so impressed, 459 00:26:41,400 --> 00:26:44,535 he decided to work on the theory himself. 460 00:26:46,105 --> 00:26:48,339 Einstein is now in a race to the finish 461 00:26:48,341 --> 00:26:53,477 with one of the world's best mathematicians. 462 00:26:55,715 --> 00:26:57,214 KAISER: This is unfolding 463 00:26:57,216 --> 00:27:00,551 in a remarkably dramatic period in history. 464 00:27:00,553 --> 00:27:04,555 World War I has begun to ravage central Europe. 465 00:27:04,557 --> 00:27:08,492 Einstein is not just toiling in the abstract; 466 00:27:08,494 --> 00:27:11,161 he's toiling as the world seems to fall apart. 467 00:27:15,901 --> 00:27:21,105 NARRATOR: By November 1915, Einstein is scheduled to present his work 468 00:27:21,107 --> 00:27:23,774 in a series of four weekly lectures 469 00:27:23,776 --> 00:27:25,743 at the esteemed Prussian Academy. 470 00:27:25,745 --> 00:27:30,881 But he's struggling to formulate his ideas. 471 00:27:30,883 --> 00:27:33,183 In the midst of these challenges, 472 00:27:33,185 --> 00:27:35,352 letters arrive from his wife in Zurich 473 00:27:35,354 --> 00:27:37,187 pressing the issue 474 00:27:37,189 --> 00:27:39,790 of his financial obligations to his family 475 00:27:39,792 --> 00:27:42,593 and discussing contact with his sons. 476 00:27:45,197 --> 00:27:47,798 As his lectures begin, 477 00:27:47,800 --> 00:27:52,136 his theory is still far from complete. 478 00:27:52,138 --> 00:27:55,039 The pressure on Einstein is huge. 479 00:27:58,244 --> 00:28:02,846 SCHAFFER: He would give a lecture, revise it, give it again. 480 00:28:02,848 --> 00:28:06,684 Spot mistakes, correct them, get up on the podium, 481 00:28:06,686 --> 00:28:09,253 explain what was wrong in the previous week's lecture, 482 00:28:09,255 --> 00:28:11,655 correct it and then move on, 483 00:28:11,657 --> 00:28:15,292 and then do that again and again for four weeks running. 484 00:28:17,830 --> 00:28:22,766 His work to convince them of the truth 485 00:28:22,768 --> 00:28:27,538 of this absolutely radical new theory of relativity 486 00:28:27,540 --> 00:28:29,339 that he was proposing 487 00:28:29,341 --> 00:28:31,809 is one of the most intense periods of work 488 00:28:31,811 --> 00:28:33,177 in the history of science. 489 00:28:42,855 --> 00:28:45,756 NARRATOR: Somehow, he's able to focus on his theory 490 00:28:45,758 --> 00:28:51,228 with an incredible intensity, and he makes his breakthrough. 491 00:28:51,230 --> 00:28:54,565 He tests his equations on a problem 492 00:28:54,567 --> 00:28:58,702 that Newton's theory of gravity couldn't solve: 493 00:28:58,704 --> 00:29:02,072 the orbit of Mercury. 494 00:29:02,074 --> 00:29:06,477 Mercury's path around the sun has an anomaly 495 00:29:06,479 --> 00:29:09,113 that Newton's theory can't explain: 496 00:29:09,115 --> 00:29:12,015 it deviates slightly each time it goes round. 497 00:29:15,121 --> 00:29:19,690 Einstein calculates the orbit with his new equations. 498 00:29:19,692 --> 00:29:22,326 The answer is correct, 499 00:29:22,328 --> 00:29:26,597 exactly what astronomers had observed. 500 00:29:26,599 --> 00:29:29,500 He'd found the final equations 501 00:29:29,502 --> 00:29:32,269 for his general theory of relativity. 502 00:29:43,249 --> 00:29:45,115 CARROLL: You have to think about the hubris of being Albert Einstein. 503 00:29:45,117 --> 00:29:47,584 He had already thrown out Newtonian mechanics 504 00:29:47,586 --> 00:29:49,620 with special relativity, and then he had gone off 505 00:29:49,622 --> 00:29:51,989 on his little personal quest to incorporate gravity. 506 00:29:51,991 --> 00:29:55,726 And at the end of the day, he boils it down to a prediction 507 00:29:55,728 --> 00:29:57,828 for a number that had been observed: 508 00:29:57,830 --> 00:29:59,730 the procession of the orbit of Mercury. 509 00:29:59,732 --> 00:30:02,332 And, miraculously, when the pages of algebra 510 00:30:02,334 --> 00:30:05,169 work out to their end, you get the right answer. 511 00:30:05,171 --> 00:30:07,738 And suddenly, it's not just playing with equations anymore; 512 00:30:07,740 --> 00:30:10,307 he realizes this is how the world works. 513 00:30:10,309 --> 00:30:14,645 All this abstract nonsense is the correct theory of reality. 514 00:30:16,582 --> 00:30:21,318 SCHAFFER: Einstein is at last able to present a successful theory. 515 00:30:21,320 --> 00:30:23,253 That's a triumphant moment, 516 00:30:23,255 --> 00:30:25,656 one of the great moments in the history of physics, 517 00:30:25,658 --> 00:30:32,196 and, for Einstein, a victory very much against the odds, 518 00:30:32,198 --> 00:30:34,097 and he'd won. 519 00:30:38,537 --> 00:30:44,541 NARRATOR: On the 25th of November 1915, Einstein lays out his findings 520 00:30:44,543 --> 00:30:50,280 in his climactic fourth lecture at the Prussian Academy. 521 00:30:50,282 --> 00:30:55,452 He presents general relativity. 522 00:30:55,454 --> 00:30:58,956 The theory can be written as a single equation. 523 00:30:58,958 --> 00:31:02,259 It condenses sprawling complexities 524 00:31:02,261 --> 00:31:06,129 into a beautifully compact set of symbols. 525 00:31:08,634 --> 00:31:12,102 So the formula is really simple: G-mu-nu equals... 526 00:31:12,104 --> 00:31:15,105 NARRATOR: G for the shape of spacetime 527 00:31:15,107 --> 00:31:19,810 and T for the distribution of mass and energy. 528 00:31:19,812 --> 00:31:23,013 So this very simple formula 529 00:31:23,015 --> 00:31:26,149 captures all of Einstein general relativity. 530 00:31:26,151 --> 00:31:28,018 It's a beautiful, simple equation 531 00:31:28,020 --> 00:31:30,988 but it's a lot of work to unpack the symbols, 532 00:31:30,990 --> 00:31:32,856 the mathematical symbols, 533 00:31:32,858 --> 00:31:35,492 and see how in this very simple formula, 534 00:31:35,494 --> 00:31:38,128 the whole geometry of the universe is hidden. 535 00:31:38,130 --> 00:31:43,300 It's kind of an acquired taste to see the beauty. 536 00:31:43,302 --> 00:31:46,403 It's also a signature formula for Einstein. 537 00:31:46,405 --> 00:31:50,674 The true mark of his genius is that he combines two elements 538 00:31:50,676 --> 00:31:53,243 that actually live in different universes. 539 00:31:53,245 --> 00:31:56,079 The left hand side lives in the world of geometry, 540 00:31:56,081 --> 00:31:57,481 of mathematics. 541 00:31:57,483 --> 00:31:59,816 The right hand side lives in the world of physics, 542 00:31:59,818 --> 00:32:01,551 of matter and movement. 543 00:32:01,553 --> 00:32:06,790 And so perhaps the most powerful ingredient of the equation 544 00:32:06,792 --> 00:32:10,060 is this very simple equal sign here, 545 00:32:10,062 --> 00:32:13,563 these two lines that actually are connecting the two worlds, 546 00:32:13,565 --> 00:32:15,499 and it's quite appropriate they're two lines 547 00:32:15,501 --> 00:32:17,200 because it's two-way traffic. 548 00:32:17,202 --> 00:32:21,972 Matter tells space and time to curve, 549 00:32:21,974 --> 00:32:25,609 space and time tells matter to move. 550 00:32:37,056 --> 00:32:39,489 NARRATOR: When Einstein presented his great theory, 551 00:32:39,491 --> 00:32:41,758 few people understood it. 552 00:32:41,760 --> 00:32:44,895 He needed a way to prove to the world 553 00:32:44,897 --> 00:32:48,532 that the counterintuitive features of his theory 554 00:32:48,534 --> 00:32:50,500 were real. 555 00:32:53,906 --> 00:32:56,807 SCHAFFER: The general theory of relativity 556 00:32:56,809 --> 00:33:00,744 made predictions of things which looked really strange. 557 00:33:03,015 --> 00:33:06,216 For example, the idea that light bends 558 00:33:06,218 --> 00:33:09,119 when it passes near a very heavy body. 559 00:33:09,121 --> 00:33:10,587 No one had ever looked for that. 560 00:33:10,589 --> 00:33:13,156 No one had ever observed it. 561 00:33:13,158 --> 00:33:14,958 Einstein was desperate, 562 00:33:14,960 --> 00:33:19,429 desperate to get astronomers to make that test. 563 00:33:19,431 --> 00:33:21,898 NARRATOR: Einstein's theory predicts that 564 00:33:21,900 --> 00:33:25,702 when light from a distant star travels close to the sun, 565 00:33:25,704 --> 00:33:31,975 the warped space around the sun bends the light's path. 566 00:33:31,977 --> 00:33:37,647 In May 1919, the English astronomer Arthur Eddington 567 00:33:37,649 --> 00:33:41,451 traveled to the African island of Principe to record images 568 00:33:41,453 --> 00:33:46,390 that would show this phenomenon. 569 00:33:46,392 --> 00:33:48,058 KAISER: What Eddington had been able to do 570 00:33:48,060 --> 00:33:50,060 was take photographs of stars 571 00:33:50,062 --> 00:33:51,895 during a total eclipse of the sun 572 00:33:51,897 --> 00:33:55,032 so the moon blocked most of the brightness of the sun 573 00:33:55,034 --> 00:33:57,901 and little pinpricks of light could be seen around the sun-- 574 00:33:57,903 --> 00:34:00,070 otherwise, it would be lost in the glare-- 575 00:34:00,072 --> 00:34:02,339 and Eddington and his colleagues were able to measure 576 00:34:02,341 --> 00:34:05,776 that the appearance of those stars had been shifted 577 00:34:05,778 --> 00:34:07,310 compared to where they would have been 578 00:34:07,312 --> 00:34:09,846 had that big mass of the sun not been deflecting that light 579 00:34:09,848 --> 00:34:12,282 from far away. 580 00:34:12,284 --> 00:34:15,519 SCHAFFER: So Eddington's able to show 581 00:34:15,521 --> 00:34:19,389 that Einstein's general relativity theory is right 582 00:34:19,391 --> 00:34:24,094 and a revolution in science has been accomplished. 583 00:34:32,504 --> 00:34:36,139 ISAACSON: When the eclipse experiments prove Einstein's theory right, 584 00:34:36,141 --> 00:34:39,543 he rockets to fame. not just because he's explained 585 00:34:39,545 --> 00:34:41,778 a new way of looking at the universe, 586 00:34:41,780 --> 00:34:43,880 but at the end of World War I, 587 00:34:43,882 --> 00:34:48,351 you had the predictions of a German scientist 588 00:34:48,353 --> 00:34:51,154 be proven right by some British astronomers, 589 00:34:51,156 --> 00:34:53,190 and it becomes headlines across the world. 590 00:34:53,192 --> 00:34:54,458 The New York Times says, 591 00:34:54,460 --> 00:34:57,194 "Lights all askew at the heavens, 592 00:34:57,196 --> 00:34:59,996 men of science more or less agog." 593 00:34:59,998 --> 00:35:01,398 This is back when newspapers 594 00:35:01,400 --> 00:35:03,033 knew how to write great headlines. 595 00:35:03,035 --> 00:35:05,669 But Einstein kind of loves this fact 596 00:35:05,671 --> 00:35:07,904 that he is now an icon of science. 597 00:35:11,877 --> 00:35:15,512 NARRATOR: Einstein becomes a worldwide celebrity, 598 00:35:15,514 --> 00:35:20,016 the icon of genius we still recognize today. 599 00:35:20,018 --> 00:35:24,921 SCHAFFER: The only person who was more widely known 600 00:35:24,923 --> 00:35:26,723 was Charlie Chaplin, 601 00:35:26,725 --> 00:35:29,626 and they got on like a house on fire. 602 00:35:29,628 --> 00:35:33,497 Chaplin said, "The reason they all love me 603 00:35:33,499 --> 00:35:36,099 "is because they understand everything I do, 604 00:35:36,101 --> 00:35:37,601 "and the reason they love you 605 00:35:37,603 --> 00:35:39,402 "is that they don't understand anything you do. 606 00:35:39,404 --> 00:35:40,570 Can you explain that?" 607 00:35:40,572 --> 00:35:42,272 And Einstein said... 608 00:35:46,545 --> 00:35:52,549 NARRATOR: But in 1930s Berlin, the Nazi party is gaining power. 609 00:35:52,551 --> 00:35:56,820 As a Jewish scientist, Einstein becomes increasingly caught up 610 00:35:56,822 --> 00:36:00,323 in the political turmoil. 611 00:36:00,325 --> 00:36:02,425 KAISER: Einstein's theories became a target. 612 00:36:02,427 --> 00:36:04,194 They were deemed aesthetically repugnant 613 00:36:04,196 --> 00:36:06,863 to a kind of Aryan sensibility. 614 00:36:06,865 --> 00:36:09,833 So people attacked not just Einstein the Jewish scientist, 615 00:36:09,835 --> 00:36:11,434 but they would actually have people 616 00:36:11,436 --> 00:36:12,936 denouncing general relativity. 617 00:36:16,808 --> 00:36:19,442 NEWS ANNOUNCER: In January, Nobel Prize mathematician Albert Einstein 618 00:36:19,444 --> 00:36:20,810 visited California... 619 00:36:20,812 --> 00:36:23,013 NARRATOR: He begins to make trips to America, 620 00:36:23,015 --> 00:36:26,516 where he is welcomed with open arms. 621 00:36:26,518 --> 00:36:30,153 NEWS ANNOUNCER: Germany's loss, America's gain. 622 00:36:30,155 --> 00:36:33,490 NARRATOR: And in 1933, he settles in Princeton 623 00:36:33,492 --> 00:36:36,026 with his second wife Elsa, 624 00:36:36,028 --> 00:36:38,595 taking up a position at the Institute for Advanced Study. 625 00:36:41,800 --> 00:36:47,337 Today, the Institute is headed by Professor Robbert Dijkgraaf. 626 00:36:47,339 --> 00:36:51,341 DIJKGRAAF: He basically was still very much by himself, 627 00:36:51,343 --> 00:36:53,577 just actually as he was in Berlin, 628 00:36:53,579 --> 00:36:57,013 just concentrating on his deep ideas 629 00:36:57,015 --> 00:37:00,784 and struggling with understanding the universe. 630 00:37:00,786 --> 00:37:03,153 Of course, his office was here. 631 00:37:03,155 --> 00:37:05,989 NARRATOR: At the Institute, 632 00:37:05,991 --> 00:37:08,825 Einstein worked to unify his theory of gravity 633 00:37:08,827 --> 00:37:12,262 with the other laws of physics. 634 00:37:14,900 --> 00:37:16,666 DIJKGRAAF: With Einstein, you see this phenomena 635 00:37:16,668 --> 00:37:18,235 you see with many great scientists-- 636 00:37:18,237 --> 00:37:21,771 that they climb this very high mountain 637 00:37:21,773 --> 00:37:26,810 and instead of celebrating their success, 638 00:37:26,812 --> 00:37:30,146 they're privileged to see a much wider landscape, 639 00:37:30,148 --> 00:37:32,782 and they see all these mountains behind it. 640 00:37:32,784 --> 00:37:35,118 And I think he was very much aware 641 00:37:35,120 --> 00:37:39,022 how much still there was to be done. 642 00:37:39,024 --> 00:37:41,891 Till the very last days of his life, 643 00:37:41,893 --> 00:37:44,294 he was trying to push these equations 644 00:37:44,296 --> 00:37:49,099 and find a description of nature, all of nature, 645 00:37:49,101 --> 00:37:54,671 in terms of the geometry of space and time. 646 00:37:54,673 --> 00:38:00,143 NARRATOR: But general relativity was fading from mainstream science. 647 00:38:00,145 --> 00:38:02,746 Physics was now focused 648 00:38:02,748 --> 00:38:07,250 on the quantum theory of atoms and tiny particles, 649 00:38:07,252 --> 00:38:11,388 a theory incompatible with Einstein's ideas, 650 00:38:11,390 --> 00:38:14,991 but one that could be tested in the lab. 651 00:38:14,993 --> 00:38:17,527 Most of general relativity 652 00:38:17,529 --> 00:38:21,398 was then beyond the reach of experiment. 653 00:38:21,400 --> 00:38:26,469 When Einstein died in 1955, age 76, 654 00:38:26,471 --> 00:38:29,839 his theory was seen as one 655 00:38:29,841 --> 00:38:33,376 with little hope of future discovery. 656 00:38:33,378 --> 00:38:36,813 CARROLL: The best theories in physics always take us to places 657 00:38:36,815 --> 00:38:38,715 where the people who invented them didn't imagine. 658 00:38:38,717 --> 00:38:41,618 And a truly wonderful theory like general relativity 659 00:38:41,620 --> 00:38:43,320 predicts all sorts of things 660 00:38:43,322 --> 00:38:45,822 that Einstein didn't conceive of. 661 00:38:45,824 --> 00:38:47,457 The theory has a life of its own. 662 00:38:47,459 --> 00:38:50,694 We understand general relativity much better right now 663 00:38:50,696 --> 00:38:52,829 than Albert Einstein ever did. 664 00:38:52,831 --> 00:38:54,798 (engines roaring) 665 00:38:54,800 --> 00:38:58,168 NEWS ANNOUNCER: Liftoff of space shuttle Discovery 666 00:38:58,170 --> 00:39:01,838 with the Hubble space telescope, our window on the universe. 667 00:39:01,840 --> 00:39:03,940 NARRATOR: Today, 100 years after general relativity 668 00:39:03,942 --> 00:39:05,408 was first presented... 669 00:39:05,410 --> 00:39:08,011 ASTRONAUT: Telescopes released, okay, thank you. 670 00:39:08,013 --> 00:39:11,381 NARRATOR: ...new technology is allowing us to explore 671 00:39:11,383 --> 00:39:14,851 the most remarkable predictions of the theory: 672 00:39:14,853 --> 00:39:16,553 an expanding universe, 673 00:39:16,555 --> 00:39:22,625 black holes, ripples in spacetime, 674 00:39:22,627 --> 00:39:27,630 and perhaps the most bizarre, 675 00:39:27,632 --> 00:39:31,301 the idea that not just space, but time itself 676 00:39:31,303 --> 00:39:35,171 is distorted by heavy objects. 677 00:39:35,173 --> 00:39:38,842 To prove it, a team of physicists 678 00:39:38,844 --> 00:39:40,443 is carrying out a remarkable experiment. 679 00:39:43,281 --> 00:39:48,118 They're using two atomic clocks that are in near perfect sync, 680 00:39:48,120 --> 00:39:51,154 accurate to a billionth of a second. 681 00:39:51,156 --> 00:39:54,257 The master clock remains at sea level 682 00:39:54,259 --> 00:39:57,627 while they take the second clock 683 00:39:57,629 --> 00:40:00,330 to the top of New Hampshire's Mount Sunapee. 684 00:40:00,332 --> 00:40:04,033 General relativity tells us that as you move away 685 00:40:04,035 --> 00:40:10,774 from the mass of the planet, time should speed up. 686 00:40:13,311 --> 00:40:16,746 After four days at the top of the mountain, 687 00:40:16,748 --> 00:40:19,616 the test clock is taken back to the lab for comparison. 688 00:40:22,821 --> 00:40:27,290 There, they compare it to the sea level master clock. 689 00:40:27,292 --> 00:40:29,058 We'll put that one into Channel A. 690 00:40:29,060 --> 00:40:32,028 NARRATOR: Four days ago, they were ticking in unison. 691 00:40:32,030 --> 00:40:33,463 Master clock in Channel B. 692 00:40:33,465 --> 00:40:34,631 NARRATOR: But what about now? 693 00:40:34,633 --> 00:40:35,765 You guys ready? 694 00:40:35,767 --> 00:40:36,933 This is it right here. 695 00:40:36,935 --> 00:40:38,435 The time interval counter is gonna show us 696 00:40:38,437 --> 00:40:41,504 the time difference between these two clock ticks. 697 00:40:43,141 --> 00:40:44,908 20 nanoseconds. 698 00:40:44,910 --> 00:40:47,444 You can see the time difference between them 699 00:40:47,446 --> 00:40:49,312 represented here graphically 700 00:40:49,314 --> 00:40:51,614 of the clock that was up at the mountain for four days 701 00:40:51,616 --> 00:40:53,850 and our master clock. 702 00:40:53,852 --> 00:40:58,121 NARRATOR: Gravity, the distortion of space and time, 703 00:40:58,123 --> 00:41:01,658 becomes weaker as you move away from the surface of the planet. 704 00:41:01,660 --> 00:41:05,728 So while the test clock was up the mountain, 705 00:41:05,730 --> 00:41:08,298 time sped up. 706 00:41:08,300 --> 00:41:13,136 It's now 20 nanoseconds, 707 00:41:13,138 --> 00:41:17,373 20 billionths of a second, ahead of the sea level clock, 708 00:41:17,375 --> 00:41:18,608 This is really awesome. 709 00:41:21,913 --> 00:41:26,616 NARRATOR: This distortion of time has surprising consequences. 710 00:41:26,618 --> 00:41:29,152 The Global Positioning System, 711 00:41:29,154 --> 00:41:32,188 something we all take for granted, 712 00:41:32,190 --> 00:41:36,259 wouldn't work without taking this into account. 713 00:41:36,261 --> 00:41:38,595 The engineers who built the GPS system 714 00:41:38,597 --> 00:41:40,730 we use every day to pinpoint locations 715 00:41:40,732 --> 00:41:44,968 had to ensure it adjusted for the time difference 716 00:41:44,970 --> 00:41:49,506 between clocks on satellites and receivers on the ground. 717 00:41:49,508 --> 00:41:55,011 If they didn't, GPS would be off by six miles every day. 718 00:41:55,013 --> 00:41:57,046 JIM GATES: Your GPS units 719 00:41:57,048 --> 00:41:59,983 use the results of general relativity. 720 00:41:59,985 --> 00:42:02,452 When you navigate in your car, 721 00:42:02,454 --> 00:42:04,921 you perhaps should give a word of thanks to Uncle Albert. 722 00:42:10,629 --> 00:42:13,463 NARRATOR: Of all general relativity's predictions 723 00:42:13,465 --> 00:42:16,499 that new technology has allowed us to explore, 724 00:42:16,501 --> 00:42:21,838 there's one that's straight out of science fiction: 725 00:42:21,840 --> 00:42:23,740 a black hole. 726 00:42:27,612 --> 00:42:31,347 Everything that we're familiar with in ordinary life 727 00:42:31,349 --> 00:42:33,216 is made from matter. 728 00:42:33,218 --> 00:42:34,817 But not black holes. 729 00:42:34,819 --> 00:42:39,088 Black holes are made from warped space and time 730 00:42:39,090 --> 00:42:43,326 and nothing else. 731 00:42:43,328 --> 00:42:47,530 A black hole is an object that is spherical, 732 00:42:47,532 --> 00:42:50,233 like a star or like the Earth, 733 00:42:50,235 --> 00:42:53,102 with a sharp boundary called the horizon 734 00:42:53,104 --> 00:42:57,307 through which nothing can come out. 735 00:42:57,309 --> 00:43:01,678 So it casts a shadow on whatever is behind it. 736 00:43:01,680 --> 00:43:07,116 It's just a black, black shadow, unbelievably black. 737 00:43:07,118 --> 00:43:12,555 NARRATOR: This simulation shows the distortion of starlight 738 00:43:12,557 --> 00:43:15,358 around a black hole. 739 00:43:15,360 --> 00:43:19,062 Even though Einstein knew his theory predicted black holes, 740 00:43:19,064 --> 00:43:24,167 he found it hard to believe they would really exist in nature. 741 00:43:24,169 --> 00:43:27,704 In the 1960s, Professor Kip Thorne 742 00:43:27,706 --> 00:43:31,741 worked on the mathematical concept of black holes. 743 00:43:31,743 --> 00:43:34,544 The idea made sense on paper, 744 00:43:34,546 --> 00:43:38,915 and he began to feel that these science fiction-like objects 745 00:43:38,917 --> 00:43:41,551 might actually be real. 746 00:43:41,553 --> 00:43:44,654 THORNE: Must be here somewhere, it's in one of these piles. 747 00:43:44,656 --> 00:43:48,424 NARRATOR: Kip Thorne made a bet with fellow physicist Stephen Hawking 748 00:43:48,426 --> 00:43:51,461 about whether or not a strong source of x-rays 749 00:43:51,463 --> 00:43:55,264 known as Cygnus X-1 was in fact a black hole. 750 00:43:55,266 --> 00:43:56,866 THORNE: I think it's in here. 751 00:43:56,868 --> 00:44:01,070 Yeah, here we go, relativity, stars and black holes. 752 00:44:01,072 --> 00:44:03,072 Yeah, there it is. 753 00:44:03,074 --> 00:44:07,010 So that is a copy of the famous bet. 754 00:44:07,012 --> 00:44:09,312 "Stephen Hawking bets a one-year subscription 755 00:44:09,314 --> 00:44:11,080 "to Penthouse magazine 756 00:44:11,082 --> 00:44:13,249 "against Kip Thorne's wager of a four-year subscription 757 00:44:13,251 --> 00:44:16,753 "to a political magazine called Private Eye 758 00:44:16,755 --> 00:44:19,489 "that Cygnus X-1 does not contain a black hole of mass 759 00:44:19,491 --> 00:44:21,557 "above the Chandrasekhar Limit. 760 00:44:21,559 --> 00:44:25,895 It's witnessed this 10th day of December 1974." 761 00:44:25,897 --> 00:44:30,033 Stephen Hawking had a terribly deep investment 762 00:44:30,035 --> 00:44:32,368 in it actually being a black hole, 763 00:44:32,370 --> 00:44:38,541 and so he made the bet against himself as an insurance policy 764 00:44:38,543 --> 00:44:40,543 that at least he would get something out of it 765 00:44:40,545 --> 00:44:43,479 if Cygnus X-1 turned out not to be a black hole. 766 00:44:43,481 --> 00:44:46,349 The evidence mounted thereafter 767 00:44:46,351 --> 00:44:48,484 over the period of the '70s and '80s, 768 00:44:48,486 --> 00:44:51,821 and in June 1990, 769 00:44:51,823 --> 00:44:56,059 Stephen snuck into my office and signed off on the bet, 770 00:44:56,061 --> 00:44:58,661 that finally, the evidence was absolutely overwhelming 771 00:44:58,663 --> 00:45:01,664 that Cygnus X-1 really is a black hole. 772 00:45:01,666 --> 00:45:05,168 And Penthouse magazine arrived. 773 00:45:05,170 --> 00:45:06,969 He sent me the British version of Penthouse, 774 00:45:06,971 --> 00:45:09,038 which was ever so much more raunchy 775 00:45:09,040 --> 00:45:10,673 than the American Penthouse, actually. 776 00:45:10,675 --> 00:45:14,677 Enough to make my face turn red when I received it at first. 777 00:45:20,618 --> 00:45:23,519 NARRATOR: Today, we have evidence suggesting that 778 00:45:23,521 --> 00:45:28,191 there are millions of black holes in our galaxy alone. 779 00:45:28,193 --> 00:45:32,595 But perhaps the most profound prediction of general relativity 780 00:45:32,597 --> 00:45:37,033 is that our universe had a hot, dense beginning 781 00:45:37,035 --> 00:45:40,069 that we call the big bang. 782 00:45:44,709 --> 00:45:48,511 The discovery that distant galaxies are moving away from us 783 00:45:48,513 --> 00:45:53,549 and that there's a background radiation permeating space 784 00:45:53,551 --> 00:45:56,152 provided evidence for the big bang 785 00:45:56,154 --> 00:45:59,055 and a universe that's growing. 786 00:45:59,057 --> 00:46:01,791 SAUL PERLMUTTER: With this picture of an expanding universe, 787 00:46:01,793 --> 00:46:03,693 there were natural questions. 788 00:46:03,695 --> 00:46:06,562 Is the universe slowing down as it expands? 789 00:46:06,564 --> 00:46:09,499 Is it so dense that someday, 790 00:46:09,501 --> 00:46:11,501 it will come to a halt and collapse? 791 00:46:11,503 --> 00:46:13,202 Will the universe come to an end? 792 00:46:13,204 --> 00:46:15,004 These seemed like good questions. 793 00:46:15,006 --> 00:46:20,710 NARRATOR: To find answers, in the 1990s, Saul Perlmutter and his team 794 00:46:20,712 --> 00:46:24,847 observed exploding stars, called supernovae, 795 00:46:24,849 --> 00:46:28,317 to track the growth of the universe. 796 00:46:28,319 --> 00:46:31,554 PERLMUTTER: When we made the measurement, we discovered that the universe 797 00:46:31,556 --> 00:46:33,356 isn't slowing down enough to come to a halt. 798 00:46:33,358 --> 00:46:35,391 In fact, it's not slowing at all; 799 00:46:35,393 --> 00:46:36,959 it's speeding up! 800 00:46:36,961 --> 00:46:39,328 The universe is expanding faster and faster. 801 00:46:39,330 --> 00:46:41,664 NARRATOR: But what's pushing it? 802 00:46:41,666 --> 00:46:45,601 PERLMUTTER: In order to explain the acceleration of the universe 803 00:46:45,603 --> 00:46:47,904 within Einstein's theory of general relativity, 804 00:46:47,906 --> 00:46:51,507 we're considering an energy spread throughout all of space 805 00:46:51,509 --> 00:46:52,842 that we've never seen before. 806 00:46:52,844 --> 00:46:54,076 We don't know what it is. 807 00:46:54,078 --> 00:46:55,812 We call it dark energy. 808 00:46:55,814 --> 00:46:59,182 And, if so, it would require 809 00:46:59,184 --> 00:47:02,652 something like 70% of all the stuff of the universe 810 00:47:02,654 --> 00:47:05,555 to be in this form of previously unknown dark energy. 811 00:47:05,557 --> 00:47:08,424 So this is a lot to swallow, 812 00:47:08,426 --> 00:47:10,359 and you might imagine that at that point, 813 00:47:10,361 --> 00:47:11,861 you should go back and revisit your theory. 814 00:47:11,863 --> 00:47:14,430 The problem is that Einstein's theory is so elegant, 815 00:47:14,432 --> 00:47:18,534 and it predicts many, many, many digits of precision, 816 00:47:18,536 --> 00:47:21,270 that it's very, very difficult to come up 817 00:47:21,272 --> 00:47:23,472 with any other theory. 818 00:47:26,244 --> 00:47:30,713 NARRATOR: There is one final prediction of general relativity 819 00:47:30,715 --> 00:47:36,352 that remains untested: gravitational waves. 820 00:47:36,354 --> 00:47:41,090 LEVIN: There are huge things in the universe happening, 821 00:47:41,092 --> 00:47:44,026 like black holes colliding or stars exploding, 822 00:47:44,028 --> 00:47:46,696 and they create these gravitational waves-- 823 00:47:46,698 --> 00:47:49,599 waves in the shape of space and time 824 00:47:49,601 --> 00:47:52,268 that travel through the universe at the speed of light. 825 00:47:52,270 --> 00:47:54,971 And so right now, the space around me 826 00:47:54,973 --> 00:47:57,974 is being squeezed and stretched by gravitational waves 827 00:47:57,976 --> 00:48:01,444 just getting here from, let's say, two black holes 828 00:48:01,446 --> 00:48:03,913 colliding a billion light years away. 829 00:48:07,218 --> 00:48:09,819 But the squeezing and stretching is so minute, 830 00:48:09,821 --> 00:48:12,755 I absolutely could not personally detect it. 831 00:48:12,757 --> 00:48:16,425 And so what we're trying to do is build an instrument that can. 832 00:48:16,427 --> 00:48:19,896 NARRATOR: In Louisiana and Washington state, 833 00:48:19,898 --> 00:48:22,865 a vast experiment called LIGO 834 00:48:22,867 --> 00:48:24,901 is in the final phases of calibration. 835 00:48:24,903 --> 00:48:30,406 It's hoped that laser beams traveling two-and-a-half miles 836 00:48:30,408 --> 00:48:32,742 between precisely aligned mirrors 837 00:48:32,744 --> 00:48:34,877 will measure the squeezing of space 838 00:48:34,879 --> 00:48:38,247 caused by gravitational waves. 839 00:48:38,249 --> 00:48:43,920 This could open up an entirely new window on the universe. 840 00:48:50,361 --> 00:48:54,664 For 100 years, general relativity 841 00:48:54,666 --> 00:48:57,967 has been proven to be correct time and time again. 842 00:48:57,969 --> 00:49:02,838 But Einstein himself knew that his great theory had limits. 843 00:49:02,840 --> 00:49:04,707 It remains incompatible 844 00:49:04,709 --> 00:49:09,845 with the quantum world of tiny atomic particles. 845 00:49:09,847 --> 00:49:12,281 Here at the Institute for Advanced study, 846 00:49:12,283 --> 00:49:13,983 where Einstein worked, 847 00:49:13,985 --> 00:49:16,919 the world's leading theoretical physicists 848 00:49:16,921 --> 00:49:21,257 are trying to solve the problem Einstein never could: 849 00:49:21,259 --> 00:49:23,793 finding a single set of rules 850 00:49:23,795 --> 00:49:27,730 that applies to both the cosmic and atomic scales. 851 00:49:27,732 --> 00:49:31,667 A unified theory. 852 00:49:31,669 --> 00:49:34,603 The Holy Grail of physics. 853 00:49:34,605 --> 00:49:38,975 We are now in what at this time is the school of physics. 854 00:49:38,977 --> 00:49:41,143 So here, people are still struggling 855 00:49:41,145 --> 00:49:43,980 with many of the same issues that Einstein would struggle 856 00:49:43,982 --> 00:49:49,418 and are still trying to capture the laws of the universe 857 00:49:49,420 --> 00:49:54,423 from the very small to the very large in a single equation. 858 00:49:54,425 --> 00:49:59,862 And it's still blackboards that are the weapon of choice. 859 00:49:59,864 --> 00:50:04,834 The brightest minds of the world are coming here 860 00:50:04,836 --> 00:50:07,837 to work 24 hours, seven days a week, 861 00:50:07,839 --> 00:50:13,342 struggling to grasp the great mysteries of the universe. 862 00:50:13,344 --> 00:50:16,112 And I think we are still driven by the same dream: 863 00:50:16,114 --> 00:50:17,980 that at some point, 864 00:50:17,982 --> 00:50:20,950 we can capture everything in elegant mathematics. 865 00:50:20,952 --> 00:50:23,652 NARRATOR: 100 years after Einstein 866 00:50:23,654 --> 00:50:27,123 transformed our understanding of nature, 867 00:50:27,125 --> 00:50:31,427 the stage is set for the next revolution. 868 00:50:31,429 --> 00:50:34,330 CARROLL: When we finally move beyond Einstein, 869 00:50:34,332 --> 00:50:36,465 it might be another singular genius that comes along-- 870 00:50:36,467 --> 00:50:39,702 someone struggling in a poor school in Kenya right now 871 00:50:39,704 --> 00:50:41,037 that we don't know about. 872 00:50:41,039 --> 00:50:42,838 Or it might be 20 different people 873 00:50:42,840 --> 00:50:44,407 with 20 different points of view 874 00:50:44,409 --> 00:50:45,908 gradually building brick-by-brick 875 00:50:45,910 --> 00:50:48,944 to finally figure out a more comprehensive view 876 00:50:48,946 --> 00:50:51,447 that includes general relativity in it. 877 00:50:58,456 --> 00:50:59,989 DIJKGRAAF: I think the most important thing 878 00:50:59,991 --> 00:51:03,025 that you learn from Einstein is just the power of an idea. 879 00:51:03,027 --> 00:51:05,928 If it's correct, you know, it's just unstoppable. 880 00:51:09,067 --> 00:51:12,635 It's extremely encouraging that he was able with pure thought 881 00:51:12,637 --> 00:51:15,304 to solve the riddle of the universe. 882 00:51:19,577 --> 00:51:22,078 LEVIN: Once we had general relativity, 883 00:51:22,080 --> 00:51:23,979 the world changed completely. 884 00:51:23,981 --> 00:51:25,948 Our point of view on the world changed completely. 885 00:51:25,950 --> 00:51:28,217 I mean, the origin of the universe 886 00:51:28,219 --> 00:51:30,586 is a prediction straight out of general relativity. 887 00:51:30,588 --> 00:51:33,456 We didn't have that before. 888 00:51:33,458 --> 00:51:36,659 GATES: I often wonder what Einstein would make 889 00:51:36,661 --> 00:51:39,261 of today's theoretical physics. 890 00:51:39,263 --> 00:51:41,564 I think he would really be saying, you know, 891 00:51:41,566 --> 00:51:43,432 "Get on with it, get the right story, get the details right." 892 00:51:47,171 --> 00:51:50,706 DIJKGRAAF: You know, you have the huge universe, 893 00:51:50,708 --> 00:51:52,508 and it obeys certain laws of nature, 894 00:51:52,510 --> 00:51:56,378 but where in the universe are these laws actually discovered? 895 00:51:56,380 --> 00:51:59,081 Where are they studied? 896 00:51:59,083 --> 00:52:01,851 And then you go to this tiny planet 897 00:52:01,853 --> 00:52:04,620 and there's this one individual, Einstein, who captures this. 898 00:52:04,622 --> 00:52:07,089 And now there's a small group of people 899 00:52:07,091 --> 00:52:10,359 walking in his footsteps and trying to push it further. 900 00:52:10,361 --> 00:52:12,361 And I often feel, 901 00:52:12,363 --> 00:52:13,996 well, it's this small part of the universe 902 00:52:13,998 --> 00:52:16,432 that actually is reflecting upon itself, 903 00:52:16,434 --> 00:52:16,432 that tries to understand itself.