1 00:00:47,446 --> 00:00:51,644 "I call Heaven and Earth to witness against you this day... 2 00:00:51,850 --> 00:00:55,684 ...that I have set before thee life and death... 3 00:00:55,888 --> 00:00:58,550 ...the blessing and the curse. 4 00:00:58,757 --> 00:01:01,920 Therefore choose life, that thou mayest live... 5 00:01:02,127 --> 00:01:04,687 ...thou and thy seed." 6 00:01:19,111 --> 00:01:22,137 Nearly 200 years ago, in the Gulf of Alaska... 7 00:01:22,347 --> 00:01:24,178 ...at a place called Lituya Bay... 8 00:01:24,383 --> 00:01:29,286 ...two cultures that had never met experienced a first encounter. 9 00:01:30,055 --> 00:01:31,249 The Tlingit people... 10 00:01:31,456 --> 00:01:34,789 ...lived more or less as their ancestors had for thousands of years. 11 00:01:34,993 --> 00:01:36,085 They were nomads... 12 00:01:36,295 --> 00:01:39,264 ...moving often by canoe between numerous campsites... 13 00:01:39,464 --> 00:01:42,160 ...where they caught plentiful fish and sea otters... 14 00:01:42,367 --> 00:01:44,528 ...and traded with neighboring tribes. 15 00:01:53,545 --> 00:01:56,275 The creator they worshiped was the raven god... 16 00:01:56,481 --> 00:02:00,008 ...whom they pictured as an enormous black bird with white wings. 17 00:02:00,218 --> 00:02:02,709 And one July day in 1786... 18 00:02:03,021 --> 00:02:05,216 ...the raven god appeared. 19 00:02:08,660 --> 00:02:10,457 The Tlingit were terrified. 20 00:02:10,662 --> 00:02:15,326 They knew that anyone looking directly at the god would be turned to stone. 21 00:02:23,008 --> 00:02:26,136 From the other side of the planet had come an expedition... 22 00:02:26,345 --> 00:02:28,870 ...led by the French explorer La Pérouse. 23 00:02:29,081 --> 00:02:34,018 It was the most elaborately planned scientific voyage of the century... 24 00:02:34,252 --> 00:02:37,813 ...sent around the world to gather knowledge about the geography... 25 00:02:38,023 --> 00:02:41,390 ...natural history and peoples of distant lands. 26 00:02:46,098 --> 00:02:47,463 But to the Tlingit... 27 00:02:47,666 --> 00:02:52,160 ...whose world was confined to the islands and inlets of south Alaska... 28 00:02:52,371 --> 00:02:56,808 ...this great vessel could have come only from the gods. 29 00:03:01,580 --> 00:03:05,482 There was one among them who dared to look more deeply. 30 00:03:05,684 --> 00:03:08,414 He was an old warrior, and nearly blind. 31 00:03:08,887 --> 00:03:11,583 He said that his life was almost over. 32 00:03:11,790 --> 00:03:14,486 For the common good, he would approach the raven... 33 00:03:14,693 --> 00:03:19,630 ...to learn whether the god really would turn his people to stone. 34 00:03:34,146 --> 00:03:37,638 He set out on his own voyage of discovery... 35 00:03:37,983 --> 00:03:41,214 ...to confront the end of the world. 36 00:04:49,221 --> 00:04:52,713 The old man made himself look hard at the raven... 37 00:04:52,924 --> 00:04:56,052 ...and saw that it was not a great bird from the sky... 38 00:04:56,261 --> 00:04:59,094 ...but the work of men like himself. 39 00:05:03,935 --> 00:05:07,132 This first encounter turned out to be peaceful. 40 00:05:07,339 --> 00:05:10,433 Men of the La Pérouse expedition were under orders... 41 00:05:10,642 --> 00:05:14,043 ...to treat with respect any people they might discover. 42 00:05:14,246 --> 00:05:17,875 An exceptional policy for its time, and after. 43 00:05:18,083 --> 00:05:20,745 La Pérouse and the Tlingit exchanged goods... 44 00:05:20,952 --> 00:05:25,582 ...and then the strange ship sailed away, never to return. 45 00:05:26,725 --> 00:05:31,025 Not all encounters between nations had been so peaceful. 46 00:05:32,097 --> 00:05:34,065 Before 1519... 47 00:05:34,266 --> 00:05:36,666 ...the Aztecs of Mexico had never seen a gun. 48 00:05:36,868 --> 00:05:39,803 They too believed at first that their strange visitors... 49 00:05:40,005 --> 00:05:42,098 ...had come from the sky. 50 00:05:55,587 --> 00:05:57,248 The Spaniards under Cortez... 51 00:05:57,455 --> 00:06:00,424 ...were not constrained by any injunctions against violence. 52 00:06:00,625 --> 00:06:04,584 Their true nature and intentions soon became clear. 53 00:06:20,145 --> 00:06:22,045 Unlike the La Pérouse expedition... 54 00:06:22,247 --> 00:06:25,978 ...the Conquistadors sought, not knowledge, but gold. 55 00:06:26,685 --> 00:06:30,348 They used their superior weapons to loot and murder. 56 00:06:30,555 --> 00:06:35,185 In their madness, they obliterated a civilization. 57 00:06:42,534 --> 00:06:44,434 In the name of piety... 58 00:06:44,636 --> 00:06:46,501 ...in a mockery of their religion... 59 00:06:46,705 --> 00:06:49,640 ...the Spaniards utterly destroyed a society... 60 00:06:49,841 --> 00:06:52,332 ...with an art, astronomy, and architecture... 61 00:06:52,544 --> 00:06:54,739 ...the equal of anything in Europe. 62 00:06:58,016 --> 00:07:01,952 We revile the Conquistadors for their cruelty and shortsightedness... 63 00:07:02,153 --> 00:07:03,814 ...for choosing death. 64 00:07:04,022 --> 00:07:08,049 We admire La Pérouse and the Tlingit for their courage and wisdom... 65 00:07:08,260 --> 00:07:10,854 ...for choosing life. 66 00:07:11,062 --> 00:07:13,030 The choice is with us still. 67 00:07:13,231 --> 00:07:17,668 But the civilization now in jeopardy is all humanity. 68 00:07:19,838 --> 00:07:21,863 As the ancient mythmakers knew... 69 00:07:22,073 --> 00:07:25,133 ...we're children equally of the Earth and sky. 70 00:07:25,343 --> 00:07:27,470 In our tenure on this planet... 71 00:07:27,679 --> 00:07:31,115 ...we've accumulated dangerous evolutionary baggage: 72 00:07:31,316 --> 00:07:33,648 Propensities for aggression and ritual... 73 00:07:33,852 --> 00:07:37,720 ...submission to leaders, hostility to outsiders. 74 00:07:37,922 --> 00:07:41,380 All of which puts our survival in some doubt. 75 00:07:41,593 --> 00:07:44,084 But we've also acquired compassion for others... 76 00:07:44,296 --> 00:07:45,422 ...love for our children... 77 00:07:45,630 --> 00:07:48,326 ...a desire to learn from history and experience... 78 00:07:48,533 --> 00:07:52,264 ...and a great, soaring, passionate intelligence. 79 00:07:52,470 --> 00:07:57,169 The clear tools for our continued survival and prosperity. 80 00:08:02,147 --> 00:08:04,775 Which aspects of our nature will prevail... 81 00:08:04,983 --> 00:08:06,314 ...is uncertain. 82 00:08:06,518 --> 00:08:10,284 Particularly when our visions and prospects are bound... 83 00:08:10,488 --> 00:08:14,356 ...to one small part of the small planet Earth. 84 00:08:14,559 --> 00:08:16,220 But up there in the cosmos... 85 00:08:16,428 --> 00:08:19,591 ...an inescapable perspective awaits. 86 00:08:19,798 --> 00:08:23,928 National boundaries are not evident when we view the Earth from space. 87 00:08:24,135 --> 00:08:27,434 Fanatic ethnic or religious or national identifications... 88 00:08:27,639 --> 00:08:29,539 ...are difficult to support... 89 00:08:29,741 --> 00:08:33,108 ...when we see our planet as a fragile blue crescent... 90 00:08:33,311 --> 00:08:36,474 ...fading to become an inconspicuous point of light... 91 00:08:36,681 --> 00:08:41,050 ...against the bastion and citadel of the stars. 92 00:08:41,886 --> 00:08:45,049 There are not yet obvious signs of extraterrestrial intelligence... 93 00:08:45,256 --> 00:08:48,384 ...and this makes us wonder whether civilizations like ours... 94 00:08:48,593 --> 00:08:52,427 ...rush inevitably, headlong to self-destruction. 95 00:08:52,630 --> 00:08:53,995 I dream about it. 96 00:08:54,199 --> 00:08:57,657 And sometimes they're bad dreams. 97 00:09:10,582 --> 00:09:12,311 In the vision of a dream... 98 00:09:12,517 --> 00:09:14,348 ...I once imagined myself... 99 00:09:14,552 --> 00:09:18,147 ...searching for other civilizations in the cosmos. 100 00:09:18,356 --> 00:09:20,688 Among a hundred billion galaxies... 101 00:09:20,892 --> 00:09:22,883 ...and a billion trillion stars... 102 00:09:23,094 --> 00:09:27,588 ...life and intelligence should have arisen on many worlds. 103 00:09:29,601 --> 00:09:33,332 Some worlds are barren and desolate... 104 00:09:33,538 --> 00:09:35,665 ...on them life never began... 105 00:09:35,874 --> 00:09:40,004 ...or may have been extinguished in some cosmic catastrophe. 106 00:09:40,211 --> 00:09:42,145 There may be worlds rich in life... 107 00:09:42,347 --> 00:09:47,182 ...but not yet evolved to intelligence and high technology. 108 00:09:47,385 --> 00:09:50,582 There may be civilizations that achieve technology... 109 00:09:50,789 --> 00:09:54,919 ...and then promptly use it to destroy themselves. 110 00:09:55,126 --> 00:09:57,686 And perhaps there are also beings... 111 00:09:57,896 --> 00:10:00,626 ...who learned to live with their technology and themselves. 112 00:10:00,832 --> 00:10:02,595 Beings who endure... 113 00:10:02,801 --> 00:10:06,828 ...and become citizens of the cosmos. 114 00:10:19,184 --> 00:10:20,845 Immersed in these thoughts... 115 00:10:21,052 --> 00:10:24,749 ...I found myself approaching a world that was clearly inhabited... 116 00:10:24,956 --> 00:10:27,424 ...a world I had visited before. 117 00:10:27,625 --> 00:10:31,083 I saw a planet encompassed by light... 118 00:10:31,296 --> 00:10:35,027 ...and recognized the signature of intelligence. 119 00:10:40,071 --> 00:10:41,538 But suddenly... 120 00:10:41,739 --> 00:10:45,869 ...darkness, total and absolute. 121 00:10:56,988 --> 00:10:58,216 In my dream... 122 00:10:58,423 --> 00:11:01,017 ...I could read the Book of Worlds. 123 00:11:01,226 --> 00:11:02,955 A vast encyclopedia... 124 00:11:03,161 --> 00:11:06,426 ...of a billion planets within the Milky Way. 125 00:11:23,681 --> 00:11:25,876 What could the computer tell me... 126 00:11:26,084 --> 00:11:29,850 ...about this now-darkened world? 127 00:11:40,064 --> 00:11:43,932 They must have survived some earlier catastrophe. 128 00:11:47,138 --> 00:11:49,868 Locally initiated contact: 129 00:11:50,074 --> 00:11:52,304 Maybe their television broadcasts. 130 00:11:54,178 --> 00:11:57,614 Their biology was different from ours. 131 00:12:00,652 --> 00:12:01,949 High technology. 132 00:12:02,153 --> 00:12:05,088 I wondered what those lights had been for. 133 00:12:07,892 --> 00:12:10,053 There must have been signs of trouble. 134 00:12:10,261 --> 00:12:12,627 Probability of survival in a century... 135 00:12:12,830 --> 00:12:15,958 ...less than 1%. Not very good odds. 136 00:12:18,102 --> 00:12:21,299 "Communications interrupted." 137 00:12:21,506 --> 00:12:23,474 Their world society had failed. 138 00:12:23,675 --> 00:12:26,803 They had made the ultimate mistake. 139 00:12:28,179 --> 00:12:32,115 I felt a longing to return to Earth. 140 00:12:33,985 --> 00:12:37,352 The television transmissions of Earth rushed past me... 141 00:12:37,555 --> 00:12:41,321 ...expanding away from our planet at the speed of light. 142 00:12:52,470 --> 00:12:55,371 The nuclear test-ban treaty was signed today. 143 00:12:55,573 --> 00:12:58,167 Something's happened in the motorcade. Stand by. 144 00:12:58,376 --> 00:13:00,970 For 64,000 dollars... 145 00:13:01,179 --> 00:13:04,410 ...bombing of Hanoi was designed to cripple morale... 146 00:13:08,052 --> 00:13:11,818 There can be no whitewash at the White House. 147 00:13:12,023 --> 00:13:15,151 ...series of record oil company profits were revealed... 148 00:13:15,360 --> 00:13:17,692 ...if the serious course of events continued. 149 00:13:17,895 --> 00:13:20,489 Foreign ministers are at this moment... 150 00:13:20,698 --> 00:13:21,824 Please stand by. 151 00:13:22,033 --> 00:13:23,466 Stand by. 152 00:13:28,039 --> 00:13:29,836 Then, suddenly... 153 00:13:30,041 --> 00:13:31,599 ...silence... 154 00:13:31,809 --> 00:13:35,745 ...total and absolute. 155 00:13:35,947 --> 00:13:39,110 But the dream was not yet done. 156 00:14:23,027 --> 00:14:24,824 Had we destroyed our home? 157 00:14:25,763 --> 00:14:28,561 What had we done to the Earth? 158 00:14:28,766 --> 00:14:31,860 There had been many ways for life to perish at our hands. 159 00:14:32,070 --> 00:14:34,436 We had poisoned the air and water. 160 00:14:34,639 --> 00:14:36,971 We had ravaged the land. 161 00:14:37,175 --> 00:14:38,938 Perhaps we had changed the climate. 162 00:14:39,844 --> 00:14:41,744 Could it have been a plague... 163 00:14:42,980 --> 00:14:44,845 ...or nuclear war? 164 00:14:52,523 --> 00:14:55,617 I remembered the galactic computer. 165 00:14:55,827 --> 00:14:58,159 What would it say about the Earth? 166 00:15:05,336 --> 00:15:07,736 There was our region of the galaxy. 167 00:15:15,346 --> 00:15:17,610 There was our world. 168 00:15:17,815 --> 00:15:20,841 I had found the entry for Earth. 169 00:15:22,220 --> 00:15:25,553 Humanity, third from the sun. 170 00:15:30,762 --> 00:15:33,060 They had heard our television broadcasts... 171 00:15:33,264 --> 00:15:37,030 ...and thought them an application for cosmic citizenship. 172 00:15:39,003 --> 00:15:41,096 Our technology had been growing enormously. 173 00:15:41,305 --> 00:15:42,829 They got that right. 174 00:15:45,510 --> 00:15:47,034 200 nation states. 175 00:15:47,245 --> 00:15:48,974 About six global powers. 176 00:15:49,180 --> 00:15:52,115 The potential to become one planet. 177 00:15:52,416 --> 00:15:56,182 Probability of survival over a century, here also... 178 00:15:56,387 --> 00:15:58,912 ...less than I%. 179 00:16:04,929 --> 00:16:07,193 So it was nuclear war. 180 00:16:07,398 --> 00:16:10,731 A full nuclear exchange. 181 00:16:10,935 --> 00:16:14,029 There would be no more big questions. 182 00:16:14,238 --> 00:16:16,229 No more answers. 183 00:16:16,440 --> 00:16:19,932 Never again a love or a child. 184 00:16:20,144 --> 00:16:23,511 No descendants to remember us and be proud. 185 00:16:23,714 --> 00:16:26,774 No more voyages to the stars. 186 00:16:26,984 --> 00:16:29,976 No more songs from the Earth. 187 00:16:34,992 --> 00:16:37,119 I saw East Africa... 188 00:16:37,328 --> 00:16:39,626 ...and thought a few million years ago... 189 00:16:39,831 --> 00:16:42,265 ...we humans took our first steps there. 190 00:16:42,466 --> 00:16:44,991 Our brains grew and changed. 191 00:16:45,203 --> 00:16:48,639 The old parts began to be guided by the new parts. 192 00:16:48,840 --> 00:16:49,966 And this made us human... 193 00:16:50,174 --> 00:16:54,406 ...with compassion and foresight and reason. 194 00:16:54,612 --> 00:16:59,208 But instead, we listened to that reptilian voice within us... 195 00:16:59,417 --> 00:17:02,944 ...counseling fear, territoriality... 196 00:17:03,154 --> 00:17:04,712 ...aggression. 197 00:17:04,922 --> 00:17:07,322 We accepted the products of science. 198 00:17:07,525 --> 00:17:09,857 We rejected its methods. 199 00:17:11,562 --> 00:17:14,827 Maybe the reptiles will evolve intelligence once more. 200 00:17:15,032 --> 00:17:19,662 Perhaps, one day, there will be civilizations again on Earth. 201 00:17:19,871 --> 00:17:21,202 There will be life. 202 00:17:21,405 --> 00:17:23,703 There will be intelligence. 203 00:17:23,908 --> 00:17:25,603 But there will be no more humans. 204 00:17:25,810 --> 00:17:30,008 Not here, not on a billion worlds. 205 00:17:53,070 --> 00:17:57,473 Every thinking person fears nuclear war... 206 00:17:57,675 --> 00:18:01,509 ...and every technological nation plans for it. 207 00:18:02,914 --> 00:18:05,474 Everyone knows it's madness... 208 00:18:05,683 --> 00:18:09,619 ...and every country has an excuse. 209 00:18:09,820 --> 00:18:14,757 There's a dreary chain of causality. 210 00:18:14,992 --> 00:18:17,961 The Germans were working on the bomb... 211 00:18:18,162 --> 00:18:20,062 ...at the beginning of World War II. 212 00:18:20,264 --> 00:18:23,324 So the Americans had to make one first. 213 00:18:23,534 --> 00:18:27,402 If the Americans had one, the Russians had to have one. 214 00:18:29,340 --> 00:18:32,036 Then, the British, the French... 215 00:18:32,243 --> 00:18:35,110 ...the Chinese, the Indians, the Pakistanis. 216 00:18:35,313 --> 00:18:38,874 Many nations now collect nuclear weapons. 217 00:18:39,083 --> 00:18:41,313 They're easy to make. 218 00:18:41,519 --> 00:18:46,218 You can steal fissionable material from nuclear reactors. 219 00:18:46,424 --> 00:18:51,361 Nuclear weapons have almost become a home handicraft industry. 220 00:18:52,263 --> 00:18:56,563 The conventional bombs of World War II were called "blockbusters." 221 00:18:56,767 --> 00:19:01,500 Filled with 20 tons of TNT, they could destroy a city block. 222 00:19:01,706 --> 00:19:05,198 All the bombs dropped on all the cities of World War II... 223 00:19:05,409 --> 00:19:07,934 ...amounted to some 2 million tons of TNT. 224 00:19:08,145 --> 00:19:09,772 Two megatons. 225 00:19:09,981 --> 00:19:12,245 Coventry and Rotterdam. 226 00:19:12,450 --> 00:19:13,940 Dresden and Tokyo. 227 00:19:14,151 --> 00:19:16,483 All the death that rained from the skies... 228 00:19:16,687 --> 00:19:19,679 ...between 1939 and 1945. 229 00:19:19,890 --> 00:19:24,759 100,000 blockbusters. Two megatons. 230 00:19:24,962 --> 00:19:29,456 Today, two megatons is the equivalent of a single thermonuclear bomb. 231 00:19:29,667 --> 00:19:32,659 One bomb with the destructive force... 232 00:19:32,870 --> 00:19:35,498 ...of the Second World War. 233 00:19:35,706 --> 00:19:38,231 But there are tens of thousands of nuclear weapons. 234 00:19:38,442 --> 00:19:41,468 The missile and bomber forces of the Soviet Union and U. S... 235 00:19:41,679 --> 00:19:46,116 ...have warheads aimed at over 15,000 designated targets. 236 00:19:46,317 --> 00:19:49,115 No place on the planet is safe. 237 00:19:49,320 --> 00:19:51,982 The energy contained in these weapons... 238 00:19:52,189 --> 00:19:53,918 ...genies of death... 239 00:19:54,125 --> 00:19:58,528 ...patiently awaiting the rubbing of the lamps... 240 00:19:58,729 --> 00:20:01,357 ...totals far more than 10,000 megatons. 241 00:20:01,565 --> 00:20:05,160 But with the destruction concentrated efficiently... 242 00:20:05,369 --> 00:20:08,600 ...not over six years, but over a few hours. 243 00:20:08,806 --> 00:20:12,742 A blockbuster for every family on the planet. 244 00:20:12,943 --> 00:20:15,810 A World War II every second... 245 00:20:16,013 --> 00:20:19,574 ...for the length of a lazy afternoon. 246 00:20:25,489 --> 00:20:27,150 The bomb dropped on Hiroshima... 247 00:20:27,358 --> 00:20:29,883 ...killed 70,000 people. 248 00:20:30,094 --> 00:20:32,289 In a full nuclear exchange... 249 00:20:32,496 --> 00:20:35,158 ...in the paroxysm of global death... 250 00:20:35,366 --> 00:20:38,199 ...the equivalent of a million Hiroshima bombs... 251 00:20:38,402 --> 00:20:41,166 ...would be dropped all over the world. 252 00:20:41,372 --> 00:20:43,397 In such an exchange not everyone would be... 253 00:20:43,607 --> 00:20:47,668 ...killed by the blast and firestorm and the immediate radiation. 254 00:20:47,878 --> 00:20:50,506 There would be other agonies: 255 00:20:50,714 --> 00:20:51,703 Loss of loved ones... 256 00:20:51,916 --> 00:20:56,319 ...the legions of the burned and blinded and mutilated... 257 00:20:56,520 --> 00:20:58,215 ...the absence of medical care... 258 00:20:58,422 --> 00:20:59,753 ...disease, plague... 259 00:20:59,957 --> 00:21:04,018 ...long-lived radiation poisoning of the soil and the water. 260 00:21:04,228 --> 00:21:09,097 The threat of tumors and stillbirths and malformed children. 261 00:21:09,300 --> 00:21:12,861 And the hopeless sense of a civilization destroyed for nothing. 262 00:21:13,070 --> 00:21:17,166 The knowledge that we could have prevented it and did not. 263 00:21:20,044 --> 00:21:23,411 The global balance of terror... 264 00:21:23,614 --> 00:21:26,378 ...pioneered by the U.S. and the Soviet Union... 265 00:21:26,584 --> 00:21:30,020 ...holds hostage all the citizens of the Earth. 266 00:21:30,221 --> 00:21:32,815 Each side persistently probes... 267 00:21:33,023 --> 00:21:35,423 ...the limits of the other's tolerance... 268 00:21:35,626 --> 00:21:39,357 ...like the Cuban missile crisis... 269 00:21:39,864 --> 00:21:42,128 ...the testing of anti-satellite weapons... 270 00:21:42,333 --> 00:21:44,824 ...the Vietnam and Afghanistan wars. 271 00:21:45,035 --> 00:21:47,003 The hostile military establishments are... 272 00:21:47,204 --> 00:21:51,004 ...locked in some ghastly mutual embrace. 273 00:21:51,208 --> 00:21:52,937 Each needs the other. 274 00:21:53,144 --> 00:21:56,875 But the balance of terror is a delicate balance... 275 00:21:57,081 --> 00:22:00,608 ...with very little margin for miscalculation. 276 00:22:02,186 --> 00:22:05,986 And the world impoverishes itself by spending... 277 00:22:06,690 --> 00:22:11,127 ...a trillion dollars a year on preparations for war. 278 00:22:11,328 --> 00:22:12,920 And by employing perhaps... 279 00:22:13,130 --> 00:22:16,190 ...half the scientists and high technologists on the planet... 280 00:22:16,400 --> 00:22:18,527 ...in military endeavors. 281 00:22:20,738 --> 00:22:22,433 How would we explain all this... 282 00:22:22,640 --> 00:22:25,006 ...to a dispassionate extraterrestrial observer? 283 00:22:25,209 --> 00:22:29,043 What account would we give of our stewardship... 284 00:22:29,246 --> 00:22:30,713 ...of the planet Earth? 285 00:22:30,915 --> 00:22:34,373 We have heard the rationales offered by the superpowers. 286 00:22:34,585 --> 00:22:37,213 We know who speaks for the nations. 287 00:22:37,421 --> 00:22:39,889 But who speaks for the human species? 288 00:22:40,090 --> 00:22:42,149 Who speaks for Earth? 289 00:22:43,327 --> 00:22:47,525 From an extraterrestrial perspective, our global civilization is... 290 00:22:47,731 --> 00:22:50,165 ...clearly on the edge of failure... 291 00:22:50,367 --> 00:22:52,267 ...in the most important task it faces: 292 00:22:52,469 --> 00:22:55,905 Preserving the lives and well-being of its citizens... 293 00:22:56,106 --> 00:22:59,269 ...and the future habitability of the planet. 294 00:22:59,476 --> 00:23:03,913 But if we're willing to live with the growing likelihood of nuclear war... 295 00:23:04,114 --> 00:23:07,277 ...shouldn't we also be willing to explore vigorously... 296 00:23:07,484 --> 00:23:10,112 ...every possible means to prevent nuclear war? 297 00:23:10,321 --> 00:23:13,017 Shouldn't we consider, in every nation... 298 00:23:13,224 --> 00:23:16,284 ...major changes in the traditional ways of doing things? 299 00:23:16,493 --> 00:23:18,290 A fundamental restructuring... 300 00:23:18,495 --> 00:23:22,124 ...of economic, political, social and religious institutions? 301 00:23:22,633 --> 00:23:25,466 We've reached a point where there can be no more... 302 00:23:25,669 --> 00:23:27,569 ...special interests or cases. 303 00:23:27,905 --> 00:23:31,432 Nuclear arms threaten every person on Earth. 304 00:23:32,810 --> 00:23:37,213 Fundamental changes in society are sometimes labeled... 305 00:23:37,414 --> 00:23:41,612 ...impractical or contrary to human nature... 306 00:23:41,819 --> 00:23:44,117 ...as if nuclear war were practical... 307 00:23:44,321 --> 00:23:47,313 ...or as if there were only one human nature. 308 00:23:47,925 --> 00:23:50,519 But fundamental changes can clearly be made. 309 00:23:50,728 --> 00:23:52,696 We're surrounded by them. 310 00:23:52,896 --> 00:23:55,558 In the last two centuries, abject slavery... 311 00:23:55,766 --> 00:23:58,326 ...which was with us for thousands of years... 312 00:23:58,535 --> 00:24:00,628 ...has almost entirely been eliminated... 313 00:24:00,838 --> 00:24:03,432 ...in a stirring worldwide revolution. 314 00:24:03,641 --> 00:24:07,236 Women, systematically mistreated for millennia... 315 00:24:07,444 --> 00:24:10,345 ...are gradually gaining the political and economic power... 316 00:24:10,547 --> 00:24:12,811 ...traditionally denied to them. 317 00:24:13,017 --> 00:24:17,613 And some wars of aggression have recently been stopped or curtailed... 318 00:24:17,821 --> 00:24:20,051 ...because of a revulsion... 319 00:24:20,257 --> 00:24:23,420 ...felt by the people in the aggressor nations. 320 00:24:23,627 --> 00:24:25,754 The old appeals... 321 00:24:25,963 --> 00:24:28,864 ...to racial, sexual, and religious chauvinism... 322 00:24:29,066 --> 00:24:32,331 ...and to rabid nationalist fervor... 323 00:24:32,536 --> 00:24:34,367 ...are beginning not to work. 324 00:24:34,571 --> 00:24:38,234 A new consciousness is developing which sees the Earth as... 325 00:24:38,442 --> 00:24:39,966 ...a single organism... 326 00:24:40,177 --> 00:24:44,307 ...and recognizes that an organism at war with itself... 327 00:24:44,515 --> 00:24:45,948 ...is doomed. 328 00:24:46,150 --> 00:24:48,880 We are one planet. 329 00:24:50,888 --> 00:24:54,517 One of the great revelations of the age of space exploration... 330 00:24:54,725 --> 00:24:57,853 ...is the image of the Earth, finite and lonely... 331 00:24:58,062 --> 00:25:02,931 ...somehow vulnerable, bearing the entire human species... 332 00:25:03,133 --> 00:25:06,864 ...through the oceans of space and time. 333 00:25:07,071 --> 00:25:09,437 But this is an ancient perception. 334 00:25:09,640 --> 00:25:11,403 In the 3rd century B. C... 335 00:25:11,608 --> 00:25:14,099 ...our planet was mapped and accurately measured... 336 00:25:14,311 --> 00:25:18,441 ...by a Greek scientist named Eratosthenes, who worked in Egypt. 337 00:25:18,649 --> 00:25:21,243 This was the world as he knew it. 338 00:25:22,019 --> 00:25:24,351 Eratosthenes was the director... 339 00:25:24,555 --> 00:25:27,251 ...of the great Library of Alexandria... 340 00:25:27,458 --> 00:25:31,724 ...the center of science and learning in the ancient world. 341 00:25:32,963 --> 00:25:37,024 Aristotle had argued that humanity was divided into Greeks... 342 00:25:37,234 --> 00:25:41,136 ...and everybody else, who he called "barbarians"... 343 00:25:41,338 --> 00:25:45,365 ...and that the Greeks should keep themselves racially pure. 344 00:25:45,576 --> 00:25:49,945 He taught that it was fitting for the Greeks to enslave other peoples. 345 00:25:50,147 --> 00:25:54,914 But Eratosthenes criticized Aristotle for his blind chauvinism. 346 00:25:55,119 --> 00:25:59,283 He believed there was good and bad in every nation. 347 00:25:59,490 --> 00:26:03,790 The Greek conquerors had invented a new god for the Egyptians... 348 00:26:03,994 --> 00:26:07,191 ...but he looked remarkably Greek. 349 00:26:07,398 --> 00:26:09,923 Alexander was portrayed as pharaoh... 350 00:26:10,134 --> 00:26:12,398 ...in a gesture to the Egyptians. 351 00:26:12,603 --> 00:26:17,097 But in practice, the Greeks were confident of their superiority. 352 00:26:18,108 --> 00:26:22,101 The protests of the librarian hardly constituted a serious challenge... 353 00:26:22,312 --> 00:26:24,109 ...to prevailing prejudices. 354 00:26:24,314 --> 00:26:27,181 Their world was as imperfect as our own. 355 00:26:27,384 --> 00:26:30,979 But the Ptolemies, the Greek kings of Egypt who followed Alexander... 356 00:26:31,188 --> 00:26:33,053 ...had at least this virtue: 357 00:26:33,257 --> 00:26:36,420 They supported the advancement of knowledge. 358 00:26:36,627 --> 00:26:39,960 Popular ideas about the nature of the cosmos were challenged... 359 00:26:40,164 --> 00:26:42,064 ...and some of them, discarded. 360 00:26:42,266 --> 00:26:43,824 New ideas were proposed... 361 00:26:44,034 --> 00:26:46,502 ...and found to be in better accord with the facts. 362 00:26:46,703 --> 00:26:49,570 There were imaginative proposals, vigorous debates... 363 00:26:49,773 --> 00:26:51,138 ...brilliant syntheses. 364 00:26:51,341 --> 00:26:53,309 The resulting treasure of knowledge... 365 00:26:53,510 --> 00:26:56,411 ...was recorded and preserved for centuries... 366 00:26:56,613 --> 00:26:59,081 ...on these shelves. 367 00:27:00,451 --> 00:27:04,319 Science came of age in this library. 368 00:27:06,924 --> 00:27:11,054 The Ptolemies didn't merely collect old knowledge. 369 00:27:11,261 --> 00:27:14,958 They supported scientific research and generated new knowledge. 370 00:27:15,165 --> 00:27:16,962 The results were amazing. 371 00:27:17,167 --> 00:27:21,570 Eratosthenes accurately calculated the size of the Earth. 372 00:27:21,772 --> 00:27:22,864 He mapped it... 373 00:27:23,073 --> 00:27:26,270 ...and he argued that it could be circumnavigated. 374 00:27:26,477 --> 00:27:30,504 Hipparchus anticipated that stars come into being... 375 00:27:30,714 --> 00:27:33,274 ...slowly move during the course of centuries... 376 00:27:33,484 --> 00:27:34,815 ...and eventually perish. 377 00:27:35,018 --> 00:27:37,009 It was he who first catalogued... 378 00:27:37,221 --> 00:27:39,951 ...the positions and magnitudes of the stars... 379 00:27:40,257 --> 00:27:43,420 ...in order to determine whether there were such changes. 380 00:27:43,627 --> 00:27:46,425 Euclid produced a textbook on geometry... 381 00:27:46,630 --> 00:27:49,793 ...which human beings learned from for 23 centuries. 382 00:27:50,000 --> 00:27:54,733 It's still a great read, full of the most elegant proofs. 383 00:27:54,938 --> 00:27:58,533 Galen wrote basic works on healing and anatomy... 384 00:27:58,742 --> 00:28:01,472 ...which dominated medicine until the Renaissance. 385 00:28:01,678 --> 00:28:03,339 These are just a few examples. 386 00:28:03,547 --> 00:28:05,879 There were dozens of great scholars here... 387 00:28:06,083 --> 00:28:09,849 ...and hundreds of fundamental discoveries. 388 00:28:14,191 --> 00:28:17,592 Some of those discoveries have a distinctly modern ring. 389 00:28:17,794 --> 00:28:21,730 Apollonius of Perga studied the parabola and the ellipse... 390 00:28:21,932 --> 00:28:25,698 ...curves that we know today describe the paths of falling objects... 391 00:28:25,903 --> 00:28:27,268 ...in a gravitational field... 392 00:28:27,471 --> 00:28:30,702 ...and space vehicles traveling between the planets. 393 00:28:30,908 --> 00:28:35,345 Heron of Alexandria invented steam engines and gear trains... 394 00:28:35,546 --> 00:28:39,380 ...he was the author of the first book on robots. 395 00:28:39,583 --> 00:28:42,916 Imagine how different our world would be if those discoveries... 396 00:28:43,120 --> 00:28:45,850 ...had been used for the benefit of everyone. 397 00:28:46,056 --> 00:28:48,923 If the humane perspective of Eratosthenes... 398 00:28:49,126 --> 00:28:51,390 ...had been widely adopted and applied. 399 00:28:51,595 --> 00:28:54,496 But this was not to be. 400 00:28:56,366 --> 00:28:59,563 Alexandria was the greatest city... 401 00:28:59,770 --> 00:29:02,864 ...the Western world had ever seen. 402 00:29:03,073 --> 00:29:05,041 People from all nations came here... 403 00:29:05,242 --> 00:29:07,437 ...to live, to trade, to learn. 404 00:29:07,644 --> 00:29:09,168 On a given day... 405 00:29:09,379 --> 00:29:12,371 ...these harbors were thronged... 406 00:29:12,583 --> 00:29:16,041 ...with merchants and scholars, tourists. 407 00:29:16,253 --> 00:29:17,447 It's probably here... 408 00:29:17,654 --> 00:29:21,181 ...that the word "cosmopolitan" realized its true meaning... 409 00:29:21,391 --> 00:29:24,656 ...of a citizen, not just of a nation... 410 00:29:24,861 --> 00:29:26,795 ...but of the cosmos. 411 00:29:26,997 --> 00:29:31,934 To be a citizen of the cosmos. 412 00:29:32,636 --> 00:29:36,766 Here were clearly the seeds of our modern world. 413 00:29:36,974 --> 00:29:39,943 But why didn't they take root and flourish? 414 00:29:40,143 --> 00:29:44,512 Why, instead, did the West slumber through 1000 years of darkness... 415 00:29:44,715 --> 00:29:48,481 ...until Columbus and Copernicus and their contemporaries... 416 00:29:48,685 --> 00:29:52,086 ...rediscovered the work done here? 417 00:29:52,289 --> 00:29:54,519 I cannot give you a simple answer... 418 00:29:54,725 --> 00:29:56,590 ...but I do know this: 419 00:29:56,793 --> 00:30:00,627 There is no record in the entire history of the library... 420 00:30:00,831 --> 00:30:04,767 ...that any of the illustrious scholars and scientists who worked here... 421 00:30:04,968 --> 00:30:07,300 ...ever seriously challenged... 422 00:30:07,504 --> 00:30:11,736 ...a single political or economic or religious assumption... 423 00:30:11,942 --> 00:30:14,240 ...of the society in which they lived. 424 00:30:14,444 --> 00:30:18,403 The permanence of the stars was questioned. 425 00:30:18,615 --> 00:30:22,483 The justice of slavery was not. 426 00:30:37,934 --> 00:30:41,165 Science and learning in general... 427 00:30:41,371 --> 00:30:43,999 ...were the preserve of the privileged few. 428 00:30:44,207 --> 00:30:48,337 The vast population of this city had not the vaguest notion... 429 00:30:48,545 --> 00:30:52,311 ...of the great discoveries being made within these walls. 430 00:30:52,516 --> 00:30:53,915 How could they? 431 00:30:54,117 --> 00:30:57,848 The new findings were not explained or popularized. 432 00:30:58,055 --> 00:31:01,456 The progress made here benefited them little. 433 00:31:01,658 --> 00:31:04,183 Science was not part of their lives. 434 00:31:04,394 --> 00:31:07,386 The discoveries in mechanics, say... 435 00:31:07,597 --> 00:31:09,428 ...or steam technology... 436 00:31:09,633 --> 00:31:13,535 ...mainly were applied to the perfection of weapons... 437 00:31:13,737 --> 00:31:16,035 ...to the encouragement of superstition... 438 00:31:16,239 --> 00:31:18,207 ...to the amusement of kings. 439 00:31:18,408 --> 00:31:22,276 Scientists never seemed to grasp the enormous potential... 440 00:31:22,479 --> 00:31:25,414 ...of machines to free people... 441 00:31:25,615 --> 00:31:29,244 ...from arduous and repetitive labor. 442 00:31:29,453 --> 00:31:31,614 The intellectual achievements of antiquity... 443 00:31:31,822 --> 00:31:34,484 ...had few practical applications. 444 00:31:34,691 --> 00:31:39,628 Science never captured the imagination of the multitude. 445 00:31:40,130 --> 00:31:43,657 There was no counterbalance to stagnation, to pessimism... 446 00:31:43,867 --> 00:31:48,270 ...to the most abject surrender to mysticism. 447 00:31:48,472 --> 00:31:51,635 So when, at long last... 448 00:31:51,842 --> 00:31:54,675 ...the mob came to burn the place down... 449 00:31:54,878 --> 00:31:57,278 ...there was nobody to stop them. 450 00:32:19,169 --> 00:32:22,195 Let me tell you about the end. 451 00:32:22,405 --> 00:32:26,671 It's a story about the last scientist to work in this place. 452 00:32:26,877 --> 00:32:30,108 A mathematician, astronomer, physicist... 453 00:32:30,313 --> 00:32:35,148 ...and head of the school of Neo- Platonic philosophy in Alexandria. 454 00:32:35,352 --> 00:32:37,582 That's an extraordinary range of accomplishments... 455 00:32:37,788 --> 00:32:40,382 ...for any individual, in any age. 456 00:32:40,590 --> 00:32:43,354 Her name was Hypatia. 457 00:32:43,560 --> 00:32:48,156 She was born in this city in the year 370 A.D. 458 00:32:50,667 --> 00:32:54,398 This was a time when women had essentially no options. 459 00:32:54,604 --> 00:32:56,936 They were considered property. 460 00:32:57,140 --> 00:33:00,837 Nevertheless, Hypatia was able to move freely... 461 00:33:01,044 --> 00:33:02,705 ...unselfconsciously... 462 00:33:02,913 --> 00:33:06,371 ...through traditional male domains. 463 00:33:06,583 --> 00:33:09,882 By all accounts, she was a great beauty. 464 00:33:10,086 --> 00:33:11,713 And although she had many suitors... 465 00:33:11,922 --> 00:33:14,823 ...she had no interest in marriage. 466 00:33:16,092 --> 00:33:21,029 The Alexandria of Hypatia's time, by then long under Roman rule... 467 00:33:21,398 --> 00:33:24,333 ...was a city in grave conflict. 468 00:33:24,534 --> 00:33:28,061 Slavery, the cancer of the ancient world... 469 00:33:28,271 --> 00:33:32,605 ...had sapped classical civilization of its vitality. 470 00:33:32,809 --> 00:33:35,243 The growing Christian Church was... 471 00:33:35,445 --> 00:33:37,345 ...consolidating its power... 472 00:33:37,547 --> 00:33:42,075 ...and attempting to eradicate pagan influence and culture. 473 00:33:42,285 --> 00:33:46,654 Hypatia stood at the focus... 474 00:33:46,857 --> 00:33:51,692 ...at the epicenter of mighty social forces. 475 00:33:51,895 --> 00:33:55,626 Cyril, the Bishop of Alexandria, despised her... 476 00:33:55,832 --> 00:33:59,962 ...in part because of her close friendship with a Roman governor... 477 00:34:00,170 --> 00:34:04,300 ...but also because she was a symbol of learning and science... 478 00:34:04,507 --> 00:34:08,944 ...which were largely identified by the early Church with paganism. 479 00:34:09,946 --> 00:34:11,675 In great personal danger... 480 00:34:11,882 --> 00:34:15,613 ...Hypatia continued to teach and to publish... 481 00:34:15,819 --> 00:34:20,449 ...until, in the year 415 A.D., on her way to work... 482 00:34:20,657 --> 00:34:22,784 ...she was set upon... 483 00:34:22,993 --> 00:34:26,360 ...by a fanatical mob of Cyril's followers. 484 00:34:26,563 --> 00:34:29,225 They dragged her from her chariot... 485 00:34:29,432 --> 00:34:31,059 ...tore off her clothes... 486 00:34:31,268 --> 00:34:35,102 ...and flayed her flesh from her bones... 487 00:34:35,305 --> 00:34:37,671 ...with abalone shells. 488 00:34:37,874 --> 00:34:41,401 Her remains were burned, her works obliterated... 489 00:34:41,611 --> 00:34:43,135 ...her name forgotten. 490 00:34:43,346 --> 00:34:46,509 Cyril was made a saint. 491 00:34:49,019 --> 00:34:52,978 The glory you see around me... 492 00:34:53,189 --> 00:34:56,022 ...is nothing but a memory. 493 00:34:56,226 --> 00:34:57,716 It does not exist. 494 00:34:59,462 --> 00:35:02,431 The last remains of the library were destroyed... 495 00:35:02,632 --> 00:35:05,157 ...within a year of Hypatia's death. 496 00:35:05,368 --> 00:35:09,031 It's as if an entire civilization had undergone... 497 00:35:09,239 --> 00:35:13,369 ...a sort of self-inflicted radical brain surgery... 498 00:35:13,743 --> 00:35:16,007 ...so that most of its memories... 499 00:35:16,212 --> 00:35:19,375 ...discoveries, ideas and passions... 500 00:35:19,582 --> 00:35:22,983 ...were irrevocably wiped out. 501 00:35:25,522 --> 00:35:28,650 The loss was incalculable. 502 00:35:28,892 --> 00:35:31,190 In some cases, we know only... 503 00:35:31,394 --> 00:35:35,023 ...the tantalizing titles of books that had been destroyed. 504 00:35:35,265 --> 00:35:39,998 In most cases, we know neither the titles nor the authors. 505 00:35:40,203 --> 00:35:42,637 We do know that in this library... 506 00:35:42,839 --> 00:35:46,866 ...there were 123 different plays by Sophocles... 507 00:35:47,077 --> 00:35:50,137 ...of which only seven have survived to our time. 508 00:35:50,347 --> 00:35:53,145 One of those seven is Oedipus Rex. 509 00:35:53,350 --> 00:35:56,217 Similar numbers apply to the lost works of... 510 00:35:56,419 --> 00:35:59,911 ...Aeschylus, Euripides, Aristophanes. 511 00:36:00,123 --> 00:36:03,786 It's a little as if the only surviving works of a man named... 512 00:36:03,994 --> 00:36:05,928 ...William Shakespeare... 513 00:36:06,129 --> 00:36:10,088 ...were Coriolanus and A Winter's Tale... 514 00:36:10,300 --> 00:36:13,292 ...although we knew he had written some other things... 515 00:36:13,503 --> 00:36:15,596 ...which were highly prized in his time. 516 00:36:15,805 --> 00:36:19,263 Plays called Hamlet, Macbeth... 517 00:36:19,476 --> 00:36:23,037 ...A Midsummer's Night Dream, Julius Caesar, King Lear... 518 00:36:23,246 --> 00:36:25,077 ...Romeo and Juliet. 519 00:36:32,222 --> 00:36:35,282 History is full of people... 520 00:36:35,492 --> 00:36:39,451 ...who, out of fear or ignorance... 521 00:36:39,662 --> 00:36:41,095 ...or the lust for power... 522 00:36:41,297 --> 00:36:45,256 ...have destroyed treasures of immeasurable value... 523 00:36:45,468 --> 00:36:49,063 ...which truly belong to all of us. 524 00:36:49,272 --> 00:36:53,106 We must not let it happen again. 525 00:37:13,963 --> 00:37:16,454 We have considered the destruction of worlds... 526 00:37:16,666 --> 00:37:19,191 ...and the end of civilizations. 527 00:37:19,402 --> 00:37:23,099 But there is another perspective by which to measure human endeavors. 528 00:37:23,306 --> 00:37:27,003 Let me tell you a story about the beginning. 529 00:37:27,510 --> 00:37:29,705 Some 15 billion years ago... 530 00:37:29,913 --> 00:37:31,437 ...our universe began... 531 00:37:31,648 --> 00:37:35,015 ...with the mightiest explosion of all time. 532 00:37:35,218 --> 00:37:38,779 The universe expanded, cooled and darkened. 533 00:37:38,988 --> 00:37:42,287 Energy condensed into matter, mostly hydrogen atoms. 534 00:37:42,492 --> 00:37:45,950 And these atoms accumulated into vast clouds... 535 00:37:46,162 --> 00:37:47,789 ...rushing away from each other... 536 00:37:47,997 --> 00:37:51,228 ...that would one day become the galaxies. 537 00:37:52,268 --> 00:37:56,466 Within these galaxies the first generation of stars was born... 538 00:37:56,673 --> 00:37:59,073 ...kindling the energy hidden in matter... 539 00:37:59,275 --> 00:38:02,005 ...flooding the cosmos with light. 540 00:38:02,212 --> 00:38:07,149 Hydrogen atoms had made suns and starlight. 541 00:38:09,052 --> 00:38:12,647 There were in those times no planets to receive the light... 542 00:38:12,856 --> 00:38:16,986 ...and no living creatures to admire the radiance of the heavens. 543 00:38:17,193 --> 00:38:19,093 But deep in the stellar furnaces... 544 00:38:19,295 --> 00:38:22,321 ...nuclear fusion was creating the heavier atoms: 545 00:38:22,532 --> 00:38:25,501 Carbon and oxygen, silicon and iron. 546 00:38:25,702 --> 00:38:28,933 These elements, the ash left by hydrogen... 547 00:38:29,139 --> 00:38:34,076 ...were the raw materials from which planets and life would later arise. 548 00:38:34,277 --> 00:38:38,213 At first, the heavy elements were trapped in the hearts of the stars. 549 00:38:38,414 --> 00:38:41,508 But massive stars soon exhausted their fuel... 550 00:38:41,718 --> 00:38:43,208 ...and in their death throes... 551 00:38:43,419 --> 00:38:46,445 ...returned most of their substance back into space. 552 00:38:46,656 --> 00:38:51,025 The interstellar gas became enriched in heavy elements. 553 00:38:52,695 --> 00:38:54,128 In the Milky Way galaxy... 554 00:38:54,330 --> 00:38:58,289 ...the matter of the cosmos was recycled into new generations of stars... 555 00:38:58,501 --> 00:39:00,469 ...now rich in heavy atoms. 556 00:39:00,670 --> 00:39:04,367 A legacy from their stellar ancestors. 557 00:39:06,075 --> 00:39:08,270 And in the cold of interstellar space... 558 00:39:08,478 --> 00:39:11,970 ...great turbulent clouds were gathered by gravity... 559 00:39:12,182 --> 00:39:15,015 ...and stirred by starlight. 560 00:39:18,922 --> 00:39:20,014 In their depths... 561 00:39:20,223 --> 00:39:23,852 ...the heavy atoms condensed into grains of rocky dust and ice... 562 00:39:24,060 --> 00:39:27,120 ...and complex carbon-based molecules. 563 00:39:27,330 --> 00:39:30,390 In accordance with the laws of physics and chemistry... 564 00:39:30,600 --> 00:39:35,469 ...hydrogen atoms had brought forth the stuff of life. 565 00:39:42,879 --> 00:39:46,246 In other clouds, more massive aggregates of gas and dust... 566 00:39:46,449 --> 00:39:48,917 ...formed later generations of stars. 567 00:39:49,118 --> 00:39:50,847 As new stars were formed... 568 00:39:51,054 --> 00:39:53,989 ...tiny condensations of matter accreted near them... 569 00:39:54,190 --> 00:39:57,887 ...inconspicuous motes of rock and metal, ice and gas... 570 00:39:58,094 --> 00:39:59,959 ...that would become the planets. 571 00:40:00,163 --> 00:40:03,132 And on these worlds, as in interstellar clouds... 572 00:40:03,333 --> 00:40:05,164 ...organic molecules formed... 573 00:40:05,368 --> 00:40:09,031 ...made of atoms that had been cooked inside the stars. 574 00:40:09,239 --> 00:40:12,299 In the tide pools and oceans of many worlds... 575 00:40:12,508 --> 00:40:16,774 ...molecules were destroyed by sunlight and assembled by chemistry. 576 00:40:16,980 --> 00:40:20,143 One day, among these natural experiments... 577 00:40:20,350 --> 00:40:23,148 ...a molecule arose, that, quite by accident... 578 00:40:23,353 --> 00:40:26,413 ...was able to make crude copies of itself. 579 00:40:32,028 --> 00:40:35,486 As time passed, self-replication became more accurate. 580 00:40:35,698 --> 00:40:37,495 Those molecules that copied better... 581 00:40:37,700 --> 00:40:39,258 ...produced more copies. 582 00:40:39,469 --> 00:40:41,960 Natural selection was underway. 583 00:40:42,171 --> 00:40:45,197 Elaborate molecular machines had evolved. 584 00:40:45,408 --> 00:40:49,674 Slowly, imperceptibly, life had begun. 585 00:40:56,586 --> 00:41:00,852 Collectives of organic molecules evolved into one-celled organisms. 586 00:41:01,057 --> 00:41:03,582 These produced multi-celled colonies. 587 00:41:03,793 --> 00:41:07,160 Their various parts became specialized organs. 588 00:41:07,363 --> 00:41:10,764 Some colonies attached themselves to the sea floor... 589 00:41:10,967 --> 00:41:13,765 ...others swam freely. 590 00:41:14,937 --> 00:41:17,997 Eyes evolved, and now the cosmos could see. 591 00:41:18,207 --> 00:41:21,370 Living things moved on to colonize the land. 592 00:41:21,577 --> 00:41:24,205 The reptiles held sway for a time... 593 00:41:24,414 --> 00:41:28,441 ...but gave way to small warm-blooded creatures with bigger brains... 594 00:41:28,651 --> 00:41:32,781 ...who developed dexterity and curiosity about their environment. 595 00:41:32,989 --> 00:41:36,356 They learned to use tools and fire and language. 596 00:41:36,559 --> 00:41:39,255 Star stuff, the ash of stellar alchemy... 597 00:41:39,462 --> 00:41:42,397 ...had emerged into consciousness. 598 00:41:52,975 --> 00:41:57,275 We are a way for the cosmos to know itself. 599 00:41:57,480 --> 00:41:59,471 We are creatures of the cosmos... 600 00:41:59,682 --> 00:42:02,981 ...and have always hungered to know our origins... 601 00:42:03,186 --> 00:42:06,815 ...to understand our connection with the universe. 602 00:42:07,023 --> 00:42:09,548 How did everything come to be? 603 00:42:11,160 --> 00:42:14,061 Every culture on the planet has devised its own response... 604 00:42:14,263 --> 00:42:17,232 ...to the riddle posed by the universe. 605 00:42:21,304 --> 00:42:25,934 Every culture celebrates the cycles of life and nature. 606 00:42:27,543 --> 00:42:29,977 There are many different ways of being human. 607 00:42:34,217 --> 00:42:36,242 But an extraterrestrial visitor... 608 00:42:36,452 --> 00:42:39,216 ...examining the differences among human societies... 609 00:42:39,422 --> 00:42:41,856 ...would find those differences trivial... 610 00:42:42,058 --> 00:42:44,390 ...compared to the similarities. 611 00:42:52,034 --> 00:42:54,935 We are one species. 612 00:43:14,657 --> 00:43:18,252 We are star stuff, harvesting starlight. 613 00:43:18,661 --> 00:43:21,596 Our lives, our past and our future... 614 00:43:21,798 --> 00:43:26,292 ...are tied to the sun, the moon and the stars. 615 00:43:29,772 --> 00:43:32,832 Our ancestors knew that their survival depended... 616 00:43:33,042 --> 00:43:34,737 ...on understanding the heavens. 617 00:43:34,944 --> 00:43:37,538 They built observatories and computers... 618 00:43:37,747 --> 00:43:42,275 ...to predict the changing of the seasons by the motions in the skies. 619 00:43:42,485 --> 00:43:44,646 We are, all of us... 620 00:43:44,854 --> 00:43:48,051 ...descended from astronomers. 621 00:43:50,226 --> 00:43:52,421 The discovery of order in the universe... 622 00:43:52,628 --> 00:43:54,118 ...of the laws of nature... 623 00:43:54,330 --> 00:43:58,494 ...is the foundation on which science builds today. 624 00:44:05,608 --> 00:44:07,200 Our conception of the cosmos... 625 00:44:07,410 --> 00:44:09,435 ...all of modern science and technology... 626 00:44:09,645 --> 00:44:13,638 ...trace back to questions raised by the stars. 627 00:44:15,284 --> 00:44:17,445 Yet, even 400 years ago... 628 00:44:17,653 --> 00:44:20,486 ...we still had no idea of our place in the universe. 629 00:44:20,690 --> 00:44:23,056 The long journey to that understanding... 630 00:44:23,259 --> 00:44:26,092 ...required both an unflinching respect for the facts... 631 00:44:26,295 --> 00:44:29,059 ...and a delight in the natural world. 632 00:44:31,834 --> 00:44:33,768 Johannes Kepler wrote: 633 00:44:33,970 --> 00:44:37,770 "We do not ask for what useful purpose the birds do sing... 634 00:44:37,974 --> 00:44:42,035 ...for song is their pleasure since they were created for singing. 635 00:44:42,378 --> 00:44:43,402 Similarly... 636 00:44:43,613 --> 00:44:46,582 ...we ought not to ask why the human mind troubles to fathom... 637 00:44:46,782 --> 00:44:48,272 ...the secrets of the heavens. 638 00:44:48,484 --> 00:44:51,715 The diversity of the phenomena of nature is so great... 639 00:44:51,921 --> 00:44:55,186 ...and the treasures hidden in the heavens so rich... 640 00:44:55,391 --> 00:44:56,824 ...precisely in order... 641 00:44:57,026 --> 00:45:01,224 ...that the human mind shall never be lacking in fresh nourishment." 642 00:45:42,705 --> 00:45:44,832 It is the birthright of every child... 643 00:45:45,041 --> 00:45:47,339 ...to encounter the cosmos anew... 644 00:45:47,543 --> 00:45:50,171 ...in every culture and every age. 645 00:45:52,682 --> 00:45:57,312 When this happens to us, we experience a deep sense of wonder. 646 00:45:57,520 --> 00:46:00,387 The most fortunate among us are guided by teachers... 647 00:46:00,590 --> 00:46:03,491 ...who channel this exhilaration. 648 00:46:05,962 --> 00:46:08,487 We are born to delight in the world. 649 00:46:08,698 --> 00:46:13,101 We are taught to distinguish our preconceptions from the truth. 650 00:46:13,302 --> 00:46:16,362 Then, new worlds are discovered... 651 00:46:16,572 --> 00:46:20,474 ...as we decipher the mysteries of the cosmos. 652 00:46:38,094 --> 00:46:40,562 Science is a collective enterprise... 653 00:46:40,763 --> 00:46:44,529 ...that embraces many cultures and spans the generations. 654 00:46:44,734 --> 00:46:48,465 In every age, and sometimes in the most unlikely places... 655 00:46:48,671 --> 00:46:51,333 ...there are those who wish with a great passion... 656 00:46:51,540 --> 00:46:53,337 ...to understand the world. 657 00:46:53,542 --> 00:46:56,534 We don't know where the next discovery will come from. 658 00:46:56,746 --> 00:47:01,410 What dream of the mind's eye will remake the world. 659 00:47:07,123 --> 00:47:11,321 These dreams begin as impossibilities. 660 00:47:14,263 --> 00:47:18,757 Once, even to see a planet through a telescope was an astonishment. 661 00:47:18,968 --> 00:47:20,526 But we studied these worlds... 662 00:47:20,736 --> 00:47:23,398 ...we figured out how they moved in their orbits... 663 00:47:23,606 --> 00:47:26,473 ...and soon we were planning voyages of discovery... 664 00:47:26,676 --> 00:47:28,109 ...beyond the Earth... 665 00:47:28,310 --> 00:47:32,804 ...and sending robot explorers to the planets and the stars. 666 00:47:47,630 --> 00:47:51,760 We humans long to be connected with our origins... 667 00:47:52,735 --> 00:47:55,203 ...so we create rituals. 668 00:47:56,372 --> 00:47:58,966 Science is another way to express this longing. 669 00:47:59,175 --> 00:48:01,439 It also connects us with our origins. 670 00:48:01,644 --> 00:48:06,013 And it, too, has its rituals and its commandments. 671 00:48:14,924 --> 00:48:19,554 Its only sacred truth is that there are no sacred truths. 672 00:48:22,565 --> 00:48:24,465 Temperature systems... 673 00:48:24,834 --> 00:48:27,359 All assumptions must be critically examined. 674 00:48:27,570 --> 00:48:30,835 Arguments from authority are worthless. 675 00:48:34,577 --> 00:48:36,943 Transducer power is on. 676 00:48:42,551 --> 00:48:44,610 Whatever is inconsistent with the facts... 677 00:48:44,820 --> 00:48:46,913 ...no matter how fond of it we are... 678 00:48:47,123 --> 00:48:50,286 ...must be discarded or revised. 679 00:48:58,801 --> 00:49:01,031 Science is not perfect. 680 00:49:01,237 --> 00:49:02,795 It's often misused. 681 00:49:03,005 --> 00:49:04,870 It's only a tool. 682 00:49:05,141 --> 00:49:06,836 But it's the best tool we have... 683 00:49:07,042 --> 00:49:09,772 ...self-correcting, ever-changing... 684 00:49:09,979 --> 00:49:12,470 ...applicable to everything. 685 00:49:18,387 --> 00:49:22,847 With this tool, we vanquish the impossible. 686 00:49:48,450 --> 00:49:50,111 With the methods of science... 687 00:49:50,319 --> 00:49:53,755 ...we have begun to explore the cosmos. 688 00:49:56,392 --> 00:49:59,020 For the first time, scientific discoveries... 689 00:49:59,228 --> 00:50:01,560 ...are widely accessible. 690 00:50:04,934 --> 00:50:06,401 Our machines... 691 00:50:06,602 --> 00:50:08,092 ...the products of science... 692 00:50:08,304 --> 00:50:10,772 ...are now beyond the orbit of Saturn. 693 00:50:17,379 --> 00:50:19,939 A preliminary spacecraft reconnaissance... 694 00:50:20,149 --> 00:50:23,141 ...has been made of 20 new worlds. 695 00:50:23,819 --> 00:50:26,879 We have learned to value careful observations... 696 00:50:27,089 --> 00:50:29,990 ...to respect the facts, even when they are disquieting... 697 00:50:30,192 --> 00:50:33,184 ...when they seem to contradict conventional wisdom. 698 00:50:34,196 --> 00:50:38,565 The Canterbury monks faithfully recorded an impact on the moon... 699 00:50:38,767 --> 00:50:42,931 ...and the Anasazi people, an explosion of a distant star. 700 00:50:43,138 --> 00:50:46,403 They saw for us as we see for them. 701 00:50:46,609 --> 00:50:50,067 We see further than they only because we stand on their shoulders. 702 00:50:50,279 --> 00:50:51,871 We build on what they knew. 703 00:50:52,081 --> 00:50:54,276 We depend on free inquiry... 704 00:50:54,483 --> 00:50:57,008 ...and free access to knowledge. 705 00:50:57,253 --> 00:51:00,745 We humans have seen the atoms which constitute all of matter... 706 00:51:00,956 --> 00:51:04,756 ...and the forces that sculpt this world and others. 707 00:51:09,899 --> 00:51:11,730 We know the molecules of life... 708 00:51:11,934 --> 00:51:14,767 ...are easily formed under conditions common... 709 00:51:14,970 --> 00:51:17,666 ...throughout the cosmos. 710 00:51:17,873 --> 00:51:21,365 We have mapped the molecular machines at the heart of life. 711 00:51:23,178 --> 00:51:26,670 We have discovered a microcosm in a drop of water. 712 00:51:26,916 --> 00:51:28,713 We have peered into the bloodstream... 713 00:51:28,918 --> 00:51:30,977 ...and down on our stormy planet... 714 00:51:31,186 --> 00:51:34,280 ...to see the Earth as a single organism. 715 00:51:34,490 --> 00:51:36,617 We have found volcanoes on other worlds... 716 00:51:36,825 --> 00:51:38,793 ...and explosions on the sun... 717 00:51:38,994 --> 00:51:41,428 ...studied comets from the depths of space... 718 00:51:41,630 --> 00:51:45,191 ...and traced their origins and destinies... 719 00:51:45,401 --> 00:51:47,164 ...listened to pulsars... 720 00:51:47,369 --> 00:51:50,304 ...and searched for other civilizations. 721 00:51:52,174 --> 00:51:55,575 We humans have set foot on another world... 722 00:51:55,778 --> 00:51:58,372 ...in a place called the Sea of Tranquility... 723 00:51:58,580 --> 00:52:01,879 ...an astonishing achievement for creatures such as we... 724 00:52:02,084 --> 00:52:05,679 ...whose earliest footsteps, 3 ½ million years old... 725 00:52:05,888 --> 00:52:10,382 ...are preserved in the volcanic ash of East Africa. 726 00:52:10,592 --> 00:52:13,083 We have walked far. 727 00:53:43,585 --> 00:53:46,679 These are some of the things that hydrogen atoms do... 728 00:53:46,889 --> 00:53:51,485 ...given 15 billion years of cosmic evolution. 729 00:53:53,529 --> 00:53:56,657 It has the sound of epic myth. 730 00:53:56,865 --> 00:53:58,298 But it's simply a description... 731 00:53:58,500 --> 00:54:00,161 ...of the evolution of the cosmos... 732 00:54:00,369 --> 00:54:03,827 ...as revealed by science in our time. 733 00:54:04,039 --> 00:54:05,301 And we... 734 00:54:05,507 --> 00:54:08,965 ...we who embody the local eyes and ears... 735 00:54:09,178 --> 00:54:11,476 ...and thoughts and feelings of the cosmos... 736 00:54:11,680 --> 00:54:15,810 ...we've begun, at last, to wonder about our origins. 737 00:54:16,018 --> 00:54:19,385 Star stuff, contemplating the stars... 738 00:54:19,588 --> 00:54:24,184 ...organized collections of 10 billion- billion-billion atoms... 739 00:54:24,393 --> 00:54:26,452 ...contemplating the evolution of matter... 740 00:54:26,662 --> 00:54:31,190 ...tracing that long path by which it arrived at consciousness... 741 00:54:31,400 --> 00:54:33,061 ...here on the planet Earth... 742 00:54:33,268 --> 00:54:36,066 ...and perhaps, throughout the cosmos. 743 00:54:36,738 --> 00:54:41,675 Our loyalties are to the species and the planet. 744 00:54:41,877 --> 00:54:43,970 We speak for Earth. 745 00:54:44,179 --> 00:54:46,670 Our obligation to survive and flourish... 746 00:54:46,882 --> 00:54:49,544 ...is owed not just to ourselves... 747 00:54:49,751 --> 00:54:54,017 ...but also to that cosmos, ancient and vast... 748 00:54:54,223 --> 00:54:56,020 ...from which we spring. 749 00:55:36,665 --> 00:55:40,192 The greatest thrill for me in reliving this adventure... 750 00:55:40,402 --> 00:55:44,463 ...has been not just that we've completed... 751 00:55:44,673 --> 00:55:47,403 ...the preliminary reconnaissance with spacecraft... 752 00:55:47,609 --> 00:55:50,134 ...of the entire solar system. 753 00:55:50,345 --> 00:55:52,370 And not just that we've discovered... 754 00:55:52,581 --> 00:55:56,483 ...astonishing structures in the realm of the galaxies... 755 00:55:56,685 --> 00:55:58,152 ...but especially... 756 00:55:58,353 --> 00:56:03,086 ...that some of Cosmos' boldest dreams about this world... 757 00:56:03,292 --> 00:56:05,453 ...are coming closer to reality. 758 00:56:05,661 --> 00:56:08,687 Since this series' maiden voyage... 759 00:56:08,897 --> 00:56:10,865 ...the impossible has come to pass. 760 00:56:11,066 --> 00:56:16,003 Mighty walls that maintained insuperable ideological differences... 761 00:56:16,305 --> 00:56:18,603 ...have come tumbling down. 762 00:56:18,807 --> 00:56:23,301 Deadly enemies have embraced and begun to work together. 763 00:56:23,512 --> 00:56:25,980 The imperative to cherish the Earth... 764 00:56:26,181 --> 00:56:30,140 ...and to protect the global environment that sustains all of us... 765 00:56:30,352 --> 00:56:32,820 ...has become widely accepted. 766 00:56:33,021 --> 00:56:35,148 And we've begun, finally... 767 00:56:35,357 --> 00:56:36,654 ...the process of reducing... 768 00:56:36,858 --> 00:56:40,726 ...the obscene number of weapons of mass destruction. 769 00:56:40,929 --> 00:56:43,727 Perhaps we have, after all... 770 00:56:43,932 --> 00:56:47,026 ...decided to choose life. 771 00:56:48,604 --> 00:56:51,801 But we still have light-years to go to ensure that choice... 772 00:56:52,007 --> 00:56:56,944 ...even after the summits and the ceremonies and the treaties. 773 00:56:57,145 --> 00:57:02,082 There are still some 50,000 nuclear weapons in the world. 774 00:57:02,417 --> 00:57:06,285 And it would require the detonation of only a tiny fraction of them... 775 00:57:06,488 --> 00:57:08,956 ...to produce a nuclear winter... 776 00:57:09,157 --> 00:57:12,126 ...the predicted global climatic catastrophe... 777 00:57:12,327 --> 00:57:16,263 ...that would result from the smoke and dust lifted into the atmosphere... 778 00:57:16,465 --> 00:57:20,731 ...by burning cities and petroleum facilities. 779 00:57:20,936 --> 00:57:24,872 The world's scientific community has begun to sound the alarm... 780 00:57:25,073 --> 00:57:27,337 ...about the grave dangers posed by... 781 00:57:27,542 --> 00:57:29,976 ...depleting the protective ozone shield... 782 00:57:30,178 --> 00:57:32,305 ...and by greenhouse warming. 783 00:57:32,514 --> 00:57:35,972 And again, we're taking some mitigating steps. 784 00:57:36,184 --> 00:57:39,711 But again, those steps are too small... 785 00:57:39,921 --> 00:57:42,412 ...and too slow. 786 00:57:42,724 --> 00:57:46,353 The discovery that such a thing as nuclear winter was really possible... 787 00:57:46,561 --> 00:57:49,860 ...evolved out of studies of Martian dust storms. 788 00:57:50,065 --> 00:57:53,831 The surface of Mars, fried by ultraviolet light... 789 00:57:54,036 --> 00:57:56,300 ...is also a reminder of why it's important... 790 00:57:56,505 --> 00:57:59,303 ...to keep our ozone layer intact. 791 00:57:59,508 --> 00:58:02,170 The runaway greenhouse effect on Venus... 792 00:58:02,377 --> 00:58:03,901 ...is a valuable reminder... 793 00:58:04,112 --> 00:58:08,606 ...that we must take the increasing greenhouse effect on Earth seriously. 794 00:58:08,817 --> 00:58:12,651 Important lessons about our environment... 795 00:58:12,854 --> 00:58:16,187 ...have come from spacecraft missions to the planets. 796 00:58:16,391 --> 00:58:18,256 By exploring other worlds... 797 00:58:18,460 --> 00:58:20,428 ...we safeguard this one. 798 00:58:20,629 --> 00:58:22,859 By itself, this fact more than justifies... 799 00:58:23,065 --> 00:58:24,999 ...the money our species has spent... 800 00:58:25,200 --> 00:58:28,966 ...in sending ships to other worlds. 801 00:58:29,571 --> 00:58:32,062 It is our fate... 802 00:58:32,274 --> 00:58:35,072 ...to live during one of the most perilous... 803 00:58:35,277 --> 00:58:37,040 ...and one of the most hopeful... 804 00:58:37,245 --> 00:58:39,213 ...chapters in human history. 805 00:58:39,414 --> 00:58:42,110 Our science and our technology... 806 00:58:42,317 --> 00:58:43,841 ...have posed us... 807 00:58:44,052 --> 00:58:46,282 ...a profound question: 808 00:58:46,488 --> 00:58:49,980 Will we learn to use these tools... 809 00:58:50,192 --> 00:58:54,561 ...with wisdom and foresight before it's too late? 810 00:58:54,763 --> 00:58:58,699 Will we see our species safely through this difficult passage... 811 00:58:58,900 --> 00:59:03,030 ...so that our children and grandchildren will continue... 812 00:59:03,238 --> 00:59:06,833 ...the great journey of discovery still deeper... 813 00:59:07,042 --> 00:59:11,536 ...into the mysteries of the cosmos? 814 00:59:11,747 --> 00:59:16,514 That same rocket and nuclear and computer technology... 815 00:59:16,718 --> 00:59:21,621 ...that sends our ships past the farthest known planet... 816 00:59:21,823 --> 00:59:25,953 ...can also be used to destroy our global civilization. 817 00:59:26,161 --> 00:59:28,721 Exactly the same technology... 818 00:59:28,930 --> 00:59:30,830 ...can be used for good... 819 00:59:31,032 --> 00:59:32,590 ...and for evil. 820 00:59:32,801 --> 00:59:35,395 It is as if... 821 00:59:35,604 --> 00:59:37,231 ...there were a god... 822 00:59:37,439 --> 00:59:39,304 ...who said to us: 823 00:59:39,508 --> 00:59:42,909 "I set before you two ways. 824 00:59:43,111 --> 00:59:46,672 You can use your technology to destroy yourselves... 825 00:59:46,882 --> 00:59:51,819 ...or to carry you to the planets and the stars. 826 00:59:52,087 --> 00:59:53,679 It's up to you."