1 00:00:01,001 --> 00:00:03,402 ¶ ¶ 2 00:00:30,930 --> 00:00:33,399 ¶ ¶ 3 00:01:00,193 --> 00:01:02,594 ¶ ¶ 4 00:01:35,795 --> 00:01:39,598 NEIL DEGRASSE TYSON: We were born into a mystery, 5 00:01:39,632 --> 00:01:41,633 one that has haunted us 6 00:01:41,668 --> 00:01:43,902 since at least as long as we've been human. 7 00:01:45,672 --> 00:01:49,274 We awakened on this tiny world 8 00:01:49,309 --> 00:01:52,211 beneath a blanket of stars, 9 00:01:52,245 --> 00:01:55,547 like an abandoned baby left on a doorstep 10 00:01:55,582 --> 00:01:58,050 without a note to explain 11 00:01:58,084 --> 00:02:00,719 where we came from, who we are, 12 00:02:00,753 --> 00:02:04,106 how our universe came to be. 13 00:02:04,157 --> 00:02:08,410 And with no idea how to end our cosmic isolation. 14 00:02:08,461 --> 00:02:12,131 We've had to figure it all out for ourselves. 15 00:02:12,165 --> 00:02:14,600 (fussing) 16 00:02:17,770 --> 00:02:19,805 Best thing we had going for us 17 00:02:19,839 --> 00:02:21,273 was our intelligence, 18 00:02:21,307 --> 00:02:24,977 especially our gift for pattern recognition, 19 00:02:25,011 --> 00:02:27,279 sharpened over eons of evolution. 20 00:02:27,313 --> 00:02:30,449 The ones who were good at spotting prey and predator, 21 00:02:30,483 --> 00:02:33,986 telling poisonous plants from the nourishing ones, 22 00:02:34,020 --> 00:02:36,955 they had a better chance to live and reproduce. 23 00:02:37,056 --> 00:02:39,458 They survived and passed on those genes 24 00:02:39,492 --> 00:02:40,859 for pattern recognition 25 00:02:40,894 --> 00:02:42,961 with its obvious advantages. 26 00:02:42,996 --> 00:02:45,531 Cultures all over the planet 27 00:02:45,565 --> 00:02:48,200 looked up at the same stars 28 00:02:48,234 --> 00:02:50,969 and found different pictures there. 29 00:02:58,011 --> 00:03:00,445 We used this gift for recognizing patterns in nature 30 00:03:00,480 --> 00:03:03,382 to read the calendar in the sky. 31 00:03:06,152 --> 00:03:08,854 The messages written in the stars 32 00:03:08,888 --> 00:03:10,722 told our forefathers and mothers 33 00:03:10,757 --> 00:03:13,625 when to camp and when to move on. 34 00:03:13,660 --> 00:03:15,227 When the migratory herds 35 00:03:15,294 --> 00:03:17,229 and when the rains and the cold would come. 36 00:03:17,231 --> 00:03:19,498 And when they would cease for a time. 37 00:03:19,532 --> 00:03:21,500 When they observed the direct connection 38 00:03:21,534 --> 00:03:23,035 between the motions of the stars 39 00:03:23,069 --> 00:03:25,137 and the seasonal cycles of life on Earth, 40 00:03:25,171 --> 00:03:27,206 they concluded, naturally, 41 00:03:27,240 --> 00:03:28,974 that what happens up there 42 00:03:29,008 --> 00:03:31,376 must be directed at us down here. 43 00:03:31,411 --> 00:03:33,195 It makes sense, right? 44 00:03:33,246 --> 00:03:35,013 If the sky was a calendar 45 00:03:35,015 --> 00:03:37,216 and somebody stuck a Post-it note on top of it, 46 00:03:37,250 --> 00:03:40,152 what else could it be but a message? 47 00:03:40,186 --> 00:03:43,355 And so, when the heavenly order was suddenly violated 48 00:03:43,389 --> 00:03:47,159 by the apparition of a comet in the sky... 49 00:03:47,193 --> 00:03:49,361 they took it personally. 50 00:03:49,363 --> 00:03:51,263 Can we really blame them? 51 00:03:51,297 --> 00:03:53,865 Back then, they had no other logical explanation 52 00:03:53,900 --> 00:03:55,367 for what was happening. 53 00:03:55,401 --> 00:03:57,002 This was long before 54 00:03:57,036 --> 00:03:58,937 anyone had yet to imagine Earth 55 00:03:58,972 --> 00:04:01,073 as a spinning planet with a tilted axis, 56 00:04:01,107 --> 00:04:02,708 revolving around the Sun. 57 00:04:02,742 --> 00:04:06,511 Every ancient human culture made the same mistake: 58 00:04:06,546 --> 00:04:08,747 a comet must be a message, 59 00:04:08,781 --> 00:04:11,583 sent by the gods... or one particular god. 60 00:04:11,618 --> 00:04:14,886 And almost invariably, our ancestors concluded 61 00:04:14,921 --> 00:04:18,724 the news was not good. 62 00:04:18,758 --> 00:04:21,460 It didn't matter if you were an ancient Aztec, 63 00:04:21,494 --> 00:04:26,198 Anglo-Saxon, Babylonian, Hindu. 64 00:04:26,232 --> 00:04:29,601 Comets were portents of doom. 65 00:04:29,636 --> 00:04:31,203 The only difference among them 66 00:04:31,237 --> 00:04:33,505 was the precise nature of the coming disaster. 67 00:04:35,258 --> 00:04:40,112 "Dis-aster," as in the Greek word for "bad star." 68 00:04:40,146 --> 00:04:42,247 To the Masai of East Africa, 69 00:04:42,282 --> 00:04:43,482 a comet meant famine. 70 00:04:43,516 --> 00:04:45,317 To the Zulu in the south, 71 00:04:45,351 --> 00:04:46,885 it meant war. 72 00:04:46,919 --> 00:04:48,987 To the Eghap people of the west, 73 00:04:49,022 --> 00:04:50,922 it meant disease. 74 00:04:50,957 --> 00:04:52,157 To the Djaga of Zaire, 75 00:04:52,191 --> 00:04:55,727 specifically "smallpox." 76 00:04:55,762 --> 00:04:57,162 To their neighbors, the Luba, 77 00:04:57,196 --> 00:05:00,932 a comet foretold the death of a leader. 78 00:05:00,967 --> 00:05:04,936 The ancient Chinese were remarkably systematic. 79 00:05:04,971 --> 00:05:08,840 Starting in roughly 1400 BC, 80 00:05:08,875 --> 00:05:11,243 they began recording and cataloguing 81 00:05:11,277 --> 00:05:12,978 the apparitions of comets. 82 00:05:13,012 --> 00:05:14,413 A three-tailed comet 83 00:05:14,447 --> 00:05:16,181 meant calamity for the state. 84 00:05:16,215 --> 00:05:17,683 A four-tailed comet 85 00:05:17,717 --> 00:05:19,985 signified an epidemic was coming. 86 00:05:20,019 --> 00:05:22,821 The human talent for pattern recognition 87 00:05:22,855 --> 00:05:24,856 is a two-edged sword. 88 00:05:24,891 --> 00:05:27,359 We're especially good at finding patterns, 89 00:05:27,393 --> 00:05:30,362 even when they aren't really there-- 90 00:05:30,396 --> 00:05:32,831 something known as "false pattern recognition." 91 00:05:37,136 --> 00:05:39,037 We hunger for significance, 92 00:05:39,072 --> 00:05:41,606 for signs that our personal existence 93 00:05:41,641 --> 00:05:44,042 is of special meaning to the universe. 94 00:05:46,312 --> 00:05:48,680 To that end, we're all too eager 95 00:05:48,715 --> 00:05:50,816 to deceive ourselves and others, 96 00:05:50,850 --> 00:05:54,353 to discern a sacred image in a grilled cheese sandwich 97 00:05:54,387 --> 00:05:57,489 or find a divine warning in a comet. 98 00:05:57,523 --> 00:06:00,225 Today, we know exactly where comets come from 99 00:06:00,259 --> 00:06:03,595 and what they're made of. 100 00:06:05,531 --> 00:06:07,332 Our Ship of the Imagination, 101 00:06:07,367 --> 00:06:11,169 fueled by equal parts of science and wonder, 102 00:06:11,204 --> 00:06:15,240 can take us anywhere in space and time. 103 00:06:15,274 --> 00:06:17,642 It can travel faster than light 104 00:06:17,677 --> 00:06:19,044 and render visible those things 105 00:06:19,078 --> 00:06:21,046 that cannot be seen. 106 00:06:21,080 --> 00:06:23,348 It's carrying us to a mysterious realm 107 00:06:23,383 --> 00:06:26,017 that lies one light-year from the Sun. 108 00:06:27,220 --> 00:06:29,220 What is this swarm of worlds? 109 00:06:29,288 --> 00:06:31,723 Was it organized by alien beings? 110 00:06:31,758 --> 00:06:32,991 No. 111 00:06:33,025 --> 00:06:34,426 Just gravity. 112 00:06:34,460 --> 00:06:36,862 These are the snows of yesteryear, 113 00:06:36,896 --> 00:06:39,998 drifting mountains of ice and rock, 114 00:06:40,032 --> 00:06:42,768 the preserved remnants of the birth of the solar system. 115 00:06:42,802 --> 00:06:45,003 It's called the Oort Cloud, 116 00:06:45,037 --> 00:06:47,572 after Jan Oort, the Dutch astronomer 117 00:06:47,607 --> 00:06:48,840 who foretold its existence 118 00:06:48,875 --> 00:06:51,276 back in 1950. 119 00:06:51,310 --> 00:06:53,578 He was trying to solve a paradox. 120 00:06:53,613 --> 00:06:56,915 There's so many ways for comets to die. 121 00:06:56,949 --> 00:06:59,184 Because they cross the orbits of planets, 122 00:06:59,218 --> 00:07:01,520 comets frequently collide with them. 123 00:07:01,554 --> 00:07:04,523 Comets are largely made of ice, 124 00:07:04,557 --> 00:07:06,358 so every time they come near the Sun, 125 00:07:06,392 --> 00:07:09,361 they lose a part of themselves through evaporation. 126 00:07:09,395 --> 00:07:11,763 And after several thousand trips, 127 00:07:11,798 --> 00:07:13,732 their ice is all gone, 128 00:07:13,833 --> 00:07:16,868 and what remains of the comet is now an asteroid. 129 00:07:16,903 --> 00:07:19,805 Comets can be gravitationally ejected from the solar system 130 00:07:19,839 --> 00:07:21,773 and exiled into space. 131 00:07:21,808 --> 00:07:23,408 And yet, somehow, 132 00:07:23,443 --> 00:07:25,243 the comets keep coming. 133 00:07:25,278 --> 00:07:27,913 Oort and other astronomers wondered, 134 00:07:27,947 --> 00:07:30,081 "Where do all the comets come from?" 135 00:07:32,418 --> 00:07:35,420 Oort calculated the rate at which new comets appear 136 00:07:35,455 --> 00:07:37,422 and concluded that there must be 137 00:07:37,457 --> 00:07:39,224 a vast, spherical swarm of them, 138 00:07:39,258 --> 00:07:41,426 a few light-years across, 139 00:07:41,461 --> 00:07:43,862 surrounding the Sun. 140 00:07:45,932 --> 00:07:49,401 Oort's logic still holds up, 141 00:07:49,435 --> 00:07:51,803 even after all the discoveries we've made about comets 142 00:07:51,838 --> 00:07:54,606 and the solar system in the many decades since. 143 00:07:54,640 --> 00:07:57,609 And yet, the Oort Cloud is a sight 144 00:07:57,643 --> 00:08:00,512 that no one has ever seen. 145 00:08:00,546 --> 00:08:01,780 Nor could we. 146 00:08:01,814 --> 00:08:04,082 It's dark out here. 147 00:08:04,116 --> 00:08:07,185 And each comet is about as far from its closest neighbor 148 00:08:07,220 --> 00:08:09,087 as the Earth is from Saturn. 149 00:08:09,188 --> 00:08:12,357 But science gives us special powers of our own. 150 00:08:12,391 --> 00:08:14,459 It gave Jan Oort 151 00:08:14,494 --> 00:08:16,495 the gift of prophecy. 152 00:08:16,529 --> 00:08:18,864 Oort was also the first to correctly estimate 153 00:08:18,898 --> 00:08:20,832 the distance between the Sun 154 00:08:20,867 --> 00:08:22,334 and the center of our galaxy. 155 00:08:22,368 --> 00:08:24,302 That's a big deal-- 156 00:08:24,337 --> 00:08:26,671 finding out where we are in the Milky Way. 157 00:08:26,706 --> 00:08:28,139 Our star is about 158 00:08:28,174 --> 00:08:30,842 30,000 light-years from the center. 159 00:08:30,877 --> 00:08:32,277 Oort was also 160 00:08:32,311 --> 00:08:34,112 the first guy to use a radio telescope 161 00:08:34,146 --> 00:08:36,448 to map the galaxy's spiral structure. 162 00:08:36,482 --> 00:08:39,551 And he discovered that the center of our galaxy 163 00:08:39,585 --> 00:08:42,988 was a place of titanic explosions, 164 00:08:43,022 --> 00:08:44,222 the first indication 165 00:08:44,257 --> 00:08:45,724 that there might have been 166 00:08:45,758 --> 00:08:47,792 a supermassive black hole lurking there. 167 00:08:47,827 --> 00:08:49,461 Does the fact that most of us know 168 00:08:49,495 --> 00:08:51,696 the names of mass murderers, 169 00:08:51,731 --> 00:08:53,532 but never heard of Jan Oort, 170 00:08:53,566 --> 00:08:55,767 say anything about us? 171 00:09:04,644 --> 00:09:07,312 The Oort Cloud is so enormous 172 00:09:07,346 --> 00:09:09,848 that it takes one of its comets about a million years 173 00:09:09,882 --> 00:09:12,751 to complete a single trip around the Sun. 174 00:09:16,122 --> 00:09:18,323 Out here, at the far edge of the solar system, 175 00:09:18,357 --> 00:09:21,493 even a little tug from the gravity of a passing star 176 00:09:21,527 --> 00:09:23,495 can liberate some of these comets 177 00:09:23,529 --> 00:09:26,798 from their gravitational bondage to the Sun. 178 00:09:30,536 --> 00:09:33,572 Some comets are flung out of the solar system 179 00:09:33,606 --> 00:09:35,040 to wander interstellar space. 180 00:09:35,074 --> 00:09:37,475 But for others, there's a different fate. 181 00:09:44,283 --> 00:09:47,218 This one is plunging towards the Sun, 182 00:09:47,253 --> 00:09:49,888 gaining speed in an unbroken free fall 183 00:09:49,989 --> 00:09:52,424 that lasts hundreds of thousands of years. 184 00:09:54,293 --> 00:09:56,528 When Neptune's gravity gives it another tug, 185 00:09:56,562 --> 00:10:00,031 there's a small change in course. 186 00:10:00,066 --> 00:10:01,600 Mighty Jupiter, the most massive 187 00:10:01,634 --> 00:10:03,034 object in our solar system-- 188 00:10:03,069 --> 00:10:05,737 other than the Sun-- attracts the comet 189 00:10:05,739 --> 00:10:07,772 with its powerful gravitational pull, 190 00:10:07,807 --> 00:10:10,241 bending its path. 191 00:10:13,579 --> 00:10:18,216 When our comet reaches the inner solar system... 192 00:10:18,250 --> 00:10:22,253 heat from the Sun bakes it. 193 00:10:29,595 --> 00:10:33,331 A beautiful transformation has begun. 194 00:10:33,366 --> 00:10:36,101 The barren, sooty iceberg 195 00:10:36,135 --> 00:10:39,604 now sports a glowing halo... 196 00:10:39,639 --> 00:10:42,040 and a tail. 197 00:10:48,848 --> 00:10:50,615 These layers tell the story 198 00:10:50,650 --> 00:10:51,933 of how the comet was made, 199 00:10:51,984 --> 00:10:54,386 some four billion years ago. 200 00:10:58,824 --> 00:11:02,494 During the 40,000 generations of humanity, 201 00:11:02,496 --> 00:11:05,096 there must have been roughly 100,000 apparitions 202 00:11:05,131 --> 00:11:06,865 of a bright comet. 203 00:11:06,899 --> 00:11:08,767 For all that time, 204 00:11:08,801 --> 00:11:13,605 the best we could do was look up in helpless wonder, 205 00:11:13,639 --> 00:11:16,107 prisoners of Earth with nowhere to turn 206 00:11:16,142 --> 00:11:19,244 for an explanation beyond our guilt and our fears. 207 00:11:20,913 --> 00:11:24,115 But then a friendship began between two men that led 208 00:11:24,150 --> 00:11:26,851 to a permanent revolution in human thought. 209 00:11:28,988 --> 00:11:32,023 Isaac Newton and Edmond Halley could not know it, 210 00:11:32,058 --> 00:11:35,794 but their collaboration would ultimately set us free 211 00:11:35,828 --> 00:11:39,264 from our long confinement on this tiny world. 212 00:11:43,836 --> 00:11:45,603 DEGRASSE TYSON: The Comet of 1664 213 00:11:45,638 --> 00:11:49,207 sent shivers of dread throughout Europe, 214 00:11:49,241 --> 00:11:51,776 and the terror seemed justified when the Plague 215 00:11:51,811 --> 00:11:54,979 and the Great Fire of London followed soon after. 216 00:11:56,382 --> 00:11:59,818 WOMAN: There, with long bloody hair, 217 00:11:59,820 --> 00:12:03,121 a blazing star threatens the world 218 00:12:03,155 --> 00:12:07,859 with famine, plague and war. 219 00:12:09,495 --> 00:12:12,163 To princes, it spells death... 220 00:12:13,332 --> 00:12:16,367 to kingdoms, many crosses... 221 00:12:16,402 --> 00:12:20,672 to all estates, inevitable losses... 222 00:12:20,706 --> 00:12:23,708 to herdsmen, rot, 223 00:12:23,743 --> 00:12:26,611 to plowmen, hapless seasons, 224 00:12:26,613 --> 00:12:31,182 to sailors, it brings storms, 225 00:12:31,217 --> 00:12:35,120 to cities, civil treasons. 226 00:12:42,261 --> 00:12:44,596 DEGRASSE TYSON: But for one child, 227 00:12:44,630 --> 00:12:47,365 the comet was not the least bit frightening. 228 00:12:52,138 --> 00:12:56,541 For him, it was a thing of wonder. 229 00:12:56,575 --> 00:12:59,611 Like all of us, Edmond Halley was born curious. 230 00:12:59,645 --> 00:13:01,746 Hell's bells! 231 00:13:01,781 --> 00:13:04,883 He was lucky to have a father who encouraged 232 00:13:04,917 --> 00:13:06,584 and nurtured his curiosity, 233 00:13:06,652 --> 00:13:09,654 buying him the best scientific instruments 234 00:13:09,656 --> 00:13:11,556 and even funding his expedition 235 00:13:11,590 --> 00:13:14,592 to make the first accurate star map of the Southern Hemisphere. 236 00:13:14,627 --> 00:13:17,462 Halley dropped out of Oxford when he was 20, 237 00:13:17,496 --> 00:13:19,430 and sailed to St. Helena, 238 00:13:19,465 --> 00:13:22,967 an island below the equator, off the west coast of Africa. 239 00:13:28,307 --> 00:13:30,074 Hell's bells. 240 00:13:30,109 --> 00:13:32,210 DEGRASSE TYSON: The problem was, nobody told Halley 241 00:13:32,244 --> 00:13:34,078 that the weather on St. Helena 242 00:13:34,113 --> 00:13:38,082 was generally lousy; it took him 12 frustrating months 243 00:13:38,117 --> 00:13:43,087 to observe enough southern stars to make a complete map. 244 00:13:43,122 --> 00:13:47,125 The gods and heroes of ancient Greece were now joined 245 00:13:47,159 --> 00:13:50,261 by the mythic figures of a new world and age: 246 00:13:50,296 --> 00:13:54,465 a toucan, a compass, a bird of paradise. 247 00:14:02,842 --> 00:14:05,844 When Halley came home with the other half of the sky, 248 00:14:05,878 --> 00:14:07,812 his map created a sensation. 249 00:14:07,847 --> 00:14:10,982 Now merchants and explorers could navigate by the stars 250 00:14:11,016 --> 00:14:12,750 visible anywhere on Earth. 251 00:14:12,785 --> 00:14:15,820 At the time, the World Society of London 252 00:14:15,855 --> 00:14:18,022 was the world's clearinghouse of scientific discovery. 253 00:14:18,057 --> 00:14:20,792 Its motto, "Nullius in verba," 254 00:14:20,826 --> 00:14:23,528 sums up the heart of the scientific method. 255 00:14:23,562 --> 00:14:26,531 It's Latin for "see for yourself." 256 00:14:26,565 --> 00:14:30,201 In other words: "question authority." 257 00:14:30,236 --> 00:14:31,870 Halley's star maps caught the attention 258 00:14:31,904 --> 00:14:34,172 of the Society's Curator of Experiments. 259 00:14:34,206 --> 00:14:35,940 I'd show him to you if I could, 260 00:14:35,975 --> 00:14:39,043 but no portrait of Robert Hooke exists from his time, 261 00:14:39,045 --> 00:14:42,013 only the verbal descriptions of his contemporaries. 262 00:14:42,047 --> 00:14:45,316 They called him "lean, bent, ugly." 263 00:14:45,334 --> 00:14:48,436 He was possibly the most inventive person who ever lived. 264 00:14:48,487 --> 00:14:50,254 And despite his appearance, 265 00:14:50,256 --> 00:14:53,358 he was the most sought-after party guest in all of London. 266 00:14:53,392 --> 00:14:55,126 Why? 267 00:14:55,160 --> 00:14:57,629 Hooke's insatiable curiosity 268 00:14:57,646 --> 00:14:59,697 encompassed absolutely everything. 269 00:15:01,834 --> 00:15:04,669 Hooke discovered a little cosmos, 270 00:15:04,703 --> 00:15:08,039 and we still call it by the name he gave it: the cell. 271 00:15:08,073 --> 00:15:09,841 Hooke discovered the cell by looking 272 00:15:09,875 --> 00:15:12,577 at a piece of cork with one of his own inventions, 273 00:15:12,611 --> 00:15:15,046 the compound microscope. 274 00:15:15,080 --> 00:15:18,383 He anticipated aspects of Darwin's theory of evolution 275 00:15:18,417 --> 00:15:21,486 by almost 200 years. 276 00:15:21,520 --> 00:15:23,588 Hooke also improved the telescope. 277 00:15:23,622 --> 00:15:26,224 The drawings he made of the astronomical bodies he observed 278 00:15:26,258 --> 00:15:28,359 attest to his uncanny precision. 279 00:15:28,394 --> 00:15:32,864 After the Great Fire destroyed central London in 1666, 280 00:15:32,898 --> 00:15:35,667 Hooke partnered with the architect Christopher Wren 281 00:15:35,701 --> 00:15:38,736 to redesign and rebuild the city. 282 00:15:38,771 --> 00:15:42,674 Hooke was the foremost experimentalist of his age. 283 00:15:42,708 --> 00:15:44,042 Using coiled springs, 284 00:15:44,076 --> 00:15:45,777 he derived the "law of elasticity," 285 00:15:45,811 --> 00:15:48,279 known today as Hooke's Law. 286 00:15:48,314 --> 00:15:50,748 He perfected the air pump, 287 00:15:50,783 --> 00:15:53,117 the height of technology in its time, 288 00:15:53,152 --> 00:15:56,888 and used it to experiment on respiration and sound. 289 00:15:56,922 --> 00:15:59,924 And he experimented with cannabis. 290 00:15:59,959 --> 00:16:02,593 He reported to a meeting of the Royal Society 291 00:16:02,628 --> 00:16:05,263 that a sea captain friend of his 292 00:16:05,297 --> 00:16:07,865 "had so often experimented with it, 293 00:16:07,900 --> 00:16:09,467 "that there is no cause of fear, 294 00:16:09,501 --> 00:16:12,403 though possibly there may be of laughter." 295 00:16:16,642 --> 00:16:19,277 But coffee was the drug of choice for England 296 00:16:19,311 --> 00:16:20,778 in the 17th century. 297 00:16:20,813 --> 00:16:23,281 Coffeehouses sprang up all over London. 298 00:16:35,561 --> 00:16:38,663 This is where people came to get news, 299 00:16:38,697 --> 00:16:42,400 to launch new ventures, and to debate ideas. 300 00:16:42,434 --> 00:16:44,802 The coffeehouse was an oasis of equality 301 00:16:44,804 --> 00:16:47,472 in a class-obsessed society. 302 00:16:47,506 --> 00:16:50,174 Here, a poor man needn't give up his seat 303 00:16:50,176 --> 00:16:52,944 to a rich man, nor submit to his opinion. 304 00:16:52,978 --> 00:16:55,279 It was a kind of laboratory of democracy. 305 00:16:55,314 --> 00:16:57,882 In this highly caffeinated atmosphere, 306 00:16:57,983 --> 00:17:02,687 Halley and Hooke met Christopher Wren to discuss a deep mystery: 307 00:17:02,721 --> 00:17:06,124 Why do the planets move as they do? 308 00:17:06,158 --> 00:17:08,659 The astronomer Johannes Kepler had demonstrated, 309 00:17:08,694 --> 00:17:10,161 some 80 years before, 310 00:17:10,195 --> 00:17:12,764 that the orbits of the planets around the Sun 311 00:17:12,798 --> 00:17:16,167 were not perfect circles, but actually ellipses, 312 00:17:16,201 --> 00:17:19,470 and that the closer a planet was to the Sun, 313 00:17:19,505 --> 00:17:22,440 the faster it moved. 314 00:17:22,474 --> 00:17:22,540 Why? 315 00:17:24,743 --> 00:17:27,311 Could some invisible force from the Sun be responsible 316 00:17:27,313 --> 00:17:28,946 for this change in motion? 317 00:17:28,948 --> 00:17:30,615 If so, how did it work? 318 00:17:30,617 --> 00:17:34,085 Could there be a simple mathematical law to describe it? 319 00:17:34,087 --> 00:17:37,889 Maybe something like Hooke's Law of Elasticity? 320 00:17:41,427 --> 00:17:43,194 Perhaps. 321 00:17:43,228 --> 00:17:44,829 But try as he might, 322 00:17:44,863 --> 00:17:46,164 Christopher Wren couldn't figure it out. 323 00:17:46,166 --> 00:17:47,465 (Wren sighs) 324 00:17:47,499 --> 00:17:49,000 Damned if I haven't tried. 325 00:17:49,034 --> 00:17:50,501 It's beyond me. 326 00:17:50,536 --> 00:17:52,503 I'll wager a book worth 40 shillings 327 00:17:52,538 --> 00:17:54,038 to the man who can solve it! 328 00:17:54,073 --> 00:17:56,174 That book is mine, Mr. Wren. 329 00:17:56,208 --> 00:17:57,542 I've already done the calculation. 330 00:17:57,576 --> 00:17:58,876 DEGRASSE TYSON: Halley was delighted. 331 00:17:58,911 --> 00:18:00,711 Show us, Mr. Hooke. 332 00:18:00,746 --> 00:18:04,315 But months passed, and Hooke failed to deliver. 333 00:18:04,349 --> 00:18:05,983 He couldn't do the math. 334 00:18:06,018 --> 00:18:07,852 None of them could. 335 00:18:07,854 --> 00:18:10,154 Finally, Halley had enough of Hooke's excuses. 336 00:18:10,189 --> 00:18:13,257 Halley knew there must be someone, somewhere, 337 00:18:13,259 --> 00:18:15,259 up to the challenge. 338 00:18:21,567 --> 00:18:24,535 What about that mathematician at Cambridge? 339 00:18:24,570 --> 00:18:26,370 Clever fellow. 340 00:18:26,405 --> 00:18:28,739 He had solved central questions about the nature of light 341 00:18:28,774 --> 00:18:32,577 years before, when he was still only 22. 342 00:18:32,611 --> 00:18:34,545 And he invented the reflecting telescope. 343 00:18:34,580 --> 00:18:36,247 Odd bird. 344 00:18:36,281 --> 00:18:38,416 Dropped out of sight a while back; 345 00:18:38,450 --> 00:18:41,552 some squabble over Hooke and his discovery about light. 346 00:18:41,587 --> 00:18:43,121 Went completely to pieces over it 347 00:18:43,155 --> 00:18:45,690 and has been hiding out in Cambridge ever since. 348 00:18:45,724 --> 00:18:48,726 Halley wondered if this strange, and by all accounts, 349 00:18:48,760 --> 00:18:51,362 exceedingly difficult man, might succeed 350 00:18:51,396 --> 00:18:52,964 where Hooke and others had failed. 351 00:18:52,998 --> 00:18:54,532 What he couldn't know, 352 00:18:54,566 --> 00:18:57,535 what no one could possibly imagine at the time, 353 00:18:57,569 --> 00:18:59,070 were the countless ways 354 00:18:59,104 --> 00:19:02,373 the world would be forever changed by this meeting 355 00:19:02,407 --> 00:19:04,842 on an August day in 1684. 356 00:19:10,082 --> 00:19:12,683 DEGRASSE TYSON: Isaac Newton was born in England 357 00:19:12,718 --> 00:19:14,986 on Christmas Day in 1642. 358 00:19:15,020 --> 00:19:16,888 (baby cries) 359 00:19:16,922 --> 00:19:20,858 Before he even opened his eyes, his father was already dead. 360 00:19:22,895 --> 00:19:25,796 His mother left him when he was only three 361 00:19:25,831 --> 00:19:28,900 and did not return until he was 11. 362 00:19:28,934 --> 00:19:32,703 When she did, it was with a new family and husband, 363 00:19:32,738 --> 00:19:35,339 a stepfather who Isaac Newton despised. 364 00:19:40,546 --> 00:19:43,748 Newton's refuge from his miserable family life 365 00:19:43,782 --> 00:19:47,585 was his passion to understand how things worked, 366 00:19:47,619 --> 00:19:50,655 especially nature itself. 367 00:19:50,689 --> 00:19:54,425 In 1661, the talented young Isaac entered Trinity College 368 00:19:54,427 --> 00:19:56,527 at Cambridge University 369 00:19:56,562 --> 00:19:59,197 where he was a consistently lousy student, 370 00:19:59,231 --> 00:20:02,033 one without friends or a loving family 371 00:20:02,067 --> 00:20:04,535 to provide any warmth or encouragement. 372 00:20:04,636 --> 00:20:08,272 Newton mostly kept to himself, sequestered in his room, 373 00:20:08,307 --> 00:20:10,775 studying ancient Greek philosophers, 374 00:20:10,809 --> 00:20:13,077 geometry and languages, 375 00:20:13,111 --> 00:20:14,845 and pondering deep questions 376 00:20:14,880 --> 00:20:19,850 on the nature of matter, space, time, and motion. 377 00:20:19,885 --> 00:20:24,555 This budding scientist was also a passionate mystic. 378 00:20:24,590 --> 00:20:26,257 Newton believed that a secret knowledge 379 00:20:26,291 --> 00:20:28,593 called alchemy, known only to a small group 380 00:20:28,627 --> 00:20:32,630 of ancient philosophers, was waiting to be rediscovered. 381 00:20:32,664 --> 00:20:36,300 He hoped to learn how to change ordinary metals 382 00:20:36,335 --> 00:20:37,935 into silver and gold, 383 00:20:37,970 --> 00:20:40,805 and maybe even cook up the elixir of life, 384 00:20:40,839 --> 00:20:42,974 the key to to immortality. 385 00:20:43,976 --> 00:20:46,877 He was also obsessed 386 00:20:46,912 --> 00:20:50,114 with finding hidden messages in the words of the Bible. 387 00:20:50,148 --> 00:20:54,452 He combed through translations in several different languages, 388 00:20:54,486 --> 00:20:57,755 hoping to decipher coded instructions from God. 389 00:21:03,895 --> 00:21:06,130 He made elaborate calculations in an effort 390 00:21:06,198 --> 00:21:10,568 to discover the date of the Second Coming. 391 00:21:10,602 --> 00:21:12,470 His lifelong research in alchemy 392 00:21:12,504 --> 00:21:15,640 and biblical chronology never led anywhere. 393 00:21:20,312 --> 00:21:23,147 When Halley found Newton that fateful day, 394 00:21:23,181 --> 00:21:27,485 he was living as a virtual recluse. 395 00:21:30,122 --> 00:21:33,024 Newton had gone into hiding 13 years earlier, 396 00:21:33,058 --> 00:21:37,628 after Robert Hooke had publicly accused Newton of stealing 397 00:21:37,729 --> 00:21:39,930 his groundbreaking work on light and color. 398 00:21:39,965 --> 00:21:42,967 In fact, it was Isaac Newton 399 00:21:43,034 --> 00:21:44,835 who solved the mystery of the spectrum of light, 400 00:21:44,870 --> 00:21:47,638 not Robert Hooke. 401 00:21:47,673 --> 00:21:49,807 This wound was painful and deep, 402 00:21:49,841 --> 00:21:52,610 and Newton resolved to never expose himself to that kind 403 00:21:52,627 --> 00:21:54,278 of public humiliation ever again. 404 00:21:54,280 --> 00:21:57,315 Sir, I don't suppose you recall 405 00:21:57,349 --> 00:21:59,350 our meeting a few years ago? 406 00:21:59,384 --> 00:22:01,252 Yes, Mr. Halley. 407 00:22:01,353 --> 00:22:02,853 I'm sorry to bother you. 408 00:22:02,888 --> 00:22:05,723 Never mind the formalities, get to your point. 409 00:22:05,757 --> 00:22:08,993 I've been talking with our friends, Mr. Wren and Mr. Hooke. 410 00:22:08,995 --> 00:22:11,996 That scoundrel Hooke's no friend of mine. 411 00:22:12,030 --> 00:22:13,798 Yes, I understand, sir. 412 00:22:13,832 --> 00:22:15,766 But the thing is we've been debating 413 00:22:15,867 --> 00:22:18,736 the puzzling question of planetary motion. 414 00:22:18,770 --> 00:22:20,638 We all agree that some force of attraction 415 00:22:20,672 --> 00:22:23,341 from the Sun governs the motions of the planets. 416 00:22:23,375 --> 00:22:26,310 We suspect there must be a mathematical law 417 00:22:26,345 --> 00:22:27,978 to describe how this force 418 00:22:28,013 --> 00:22:30,464 changes with distance. 419 00:22:30,515 --> 00:22:31,816 And knowing of your skill... 420 00:22:31,850 --> 00:22:33,150 Yes, yes, the attraction of gravity 421 00:22:33,185 --> 00:22:35,386 weakens with the square of the distance. 422 00:22:35,420 --> 00:22:37,988 That's why the planets move in ellipses. 423 00:22:38,023 --> 00:22:40,591 But, sir, how can you know this? 424 00:22:40,625 --> 00:22:43,527 Why, I have calculated it some five years ago. 425 00:22:43,562 --> 00:22:46,430 I beg you, show it to me. 426 00:22:46,465 --> 00:22:47,832 The calculation is here... 427 00:22:47,866 --> 00:22:49,834 somewhere. 428 00:22:49,836 --> 00:22:51,068 Well, no matter. 429 00:22:51,103 --> 00:22:52,536 I shall redo it and be sure 430 00:22:52,571 --> 00:22:53,604 to send it on to you. 431 00:22:53,638 --> 00:22:55,105 This is stupendous! 432 00:22:55,107 --> 00:22:57,375 Why have we not had word of it before? 433 00:22:57,409 --> 00:22:59,210 DEGRASSE TYSON: Newton remembered all too well 434 00:22:59,244 --> 00:23:02,246 what Hooke had done to him 435 00:23:02,248 --> 00:23:04,899 the last time he put forth an idea. 436 00:23:04,950 --> 00:23:07,001 Just when Halley may have begun to wonder 437 00:23:07,052 --> 00:23:10,187 if Newton was bluffing as Hooke had done earlier, 438 00:23:10,222 --> 00:23:14,058 a messenger arrived with an envelope from Newton. 439 00:23:16,962 --> 00:23:20,731 Here are the opening pages of modern science 440 00:23:20,766 --> 00:23:24,034 with its all-embracing vision of nature... 441 00:23:24,069 --> 00:23:27,771 universal laws of motion, gravity... 442 00:23:27,839 --> 00:23:29,440 not just for the Earth, 443 00:23:29,474 --> 00:23:32,410 but for the cosmos. 444 00:23:32,444 --> 00:23:35,713 Halley raced back to Cambridge. 445 00:23:35,747 --> 00:23:38,783 Mr. Newton, I beseech you to work all of this 446 00:23:38,817 --> 00:23:41,385 into a book as soon as possible. 447 00:23:41,420 --> 00:23:44,889 I can assure you the Royal Society will publish it. 448 00:23:44,923 --> 00:23:46,740 DEGRASSE TYSON: But there was one little problem. 449 00:23:46,792 --> 00:23:49,226 We are in agreement 450 00:23:49,261 --> 00:23:52,396 that Mr. Newton has produced a masterpiece. 451 00:23:52,431 --> 00:23:56,066 However, I'm afraid the Royal Society has... 452 00:23:56,118 --> 00:24:00,004 well, regrettably sales for the History of Fish... 453 00:24:00,071 --> 00:24:03,874 have not lived up to expectations. 454 00:24:03,975 --> 00:24:06,777 DEGRASSE TYSON: It's an impressive book. 455 00:24:06,812 --> 00:24:08,679 Extremely comprehensive. 456 00:24:08,713 --> 00:24:10,481 Really. 457 00:24:10,515 --> 00:24:14,018 It's filled with lavish illustrations of... 458 00:24:14,052 --> 00:24:17,488 well, fish. 459 00:24:17,522 --> 00:24:19,924 The disappointing sales led to a bigger problem. 460 00:24:19,958 --> 00:24:22,460 The Royal Society pretty much blew 461 00:24:22,494 --> 00:24:25,463 its total annual budget on the History of Fish. 462 00:24:25,497 --> 00:24:28,199 In fact, they were so strapped for cash, 463 00:24:28,233 --> 00:24:30,634 they had to pay poor Halley's salary 464 00:24:30,702 --> 00:24:33,337 with copies of their worst-selling book. 465 00:24:33,371 --> 00:24:36,540 With no money to print Newton's Principia, 466 00:24:36,575 --> 00:24:39,677 the scientific revolution hung in the balance. 467 00:24:45,200 --> 00:24:46,200 Without Halley's heroic efforts, 468 00:24:46,202 --> 00:24:47,468 the reclusive Newton's masterwork 469 00:24:47,470 --> 00:24:48,502 might never have seen the light of day. 470 00:24:48,504 --> 00:24:50,704 But Halley was a man on a mission, 471 00:24:50,706 --> 00:24:54,308 absolutely determined to bring Newton's genius to the world. 472 00:24:54,310 --> 00:24:56,877 That pre-scientific world, 473 00:24:56,879 --> 00:24:59,346 the world ruled by fear, 474 00:24:59,348 --> 00:25:02,483 was poised at the edge of a revolution. 475 00:25:02,485 --> 00:25:05,853 Everything depended on whether or not Edmond Halley 476 00:25:05,855 --> 00:25:08,856 could get Newton's book out to the wider world. 477 00:25:08,858 --> 00:25:11,659 Halley resolved not only to edit Newton's book, 478 00:25:11,661 --> 00:25:14,662 but to publish it at his own expense. 479 00:25:14,664 --> 00:25:16,597 Newton completed the first two volumes, 480 00:25:16,599 --> 00:25:18,766 laying the mathematical framework 481 00:25:18,768 --> 00:25:21,335 for the physics of motion. 482 00:25:21,337 --> 00:25:24,371 The third volume would settle once and for all 483 00:25:24,373 --> 00:25:26,240 who won the coffeehouse wager. 484 00:25:26,242 --> 00:25:28,509 Newton applied his principles to explain 485 00:25:28,511 --> 00:25:30,644 all the known motions of the Earth, 486 00:25:30,646 --> 00:25:33,013 the Moon and the planets. 487 00:25:33,015 --> 00:25:35,916 Unfortunately, there was this problem. 488 00:25:36,017 --> 00:25:37,818 Now Halley also took on the role 489 00:25:37,852 --> 00:25:40,754 of Newton's psychotherapist. 490 00:25:40,756 --> 00:25:44,124 Isaac, I'm afraid that Mr. Hooke requires 491 00:25:44,159 --> 00:25:47,461 an acknowledgment in the preface of your third volume. 492 00:25:47,495 --> 00:25:48,729 But I have done so. 493 00:25:48,830 --> 00:25:50,931 Thanking him, Mr. Wren and yourself 494 00:25:50,966 --> 00:25:54,034 for prodding me to think again on astronomical matters. 495 00:25:54,069 --> 00:25:57,271 Mr. Hooke has been going about London saying 496 00:25:57,305 --> 00:25:59,773 that you got the Law of Gravity from him. 497 00:25:59,808 --> 00:26:01,375 Why, that litigious little... 498 00:26:01,409 --> 00:26:02,710 Never! 499 00:26:02,744 --> 00:26:04,545 I would sooner burn the third volume 500 00:26:04,579 --> 00:26:06,547 than deface it with such a lie. 501 00:26:06,581 --> 00:26:08,015 To hell with Hooke. 502 00:26:08,049 --> 00:26:09,350 He will be long forgotten 503 00:26:09,384 --> 00:26:11,685 when your ideas are still being celebrated. 504 00:26:13,555 --> 00:26:17,625 More copies of that dreadful book? 505 00:26:17,642 --> 00:26:20,427 Wherever shall we put them all? 506 00:26:20,429 --> 00:26:21,895 We talked about this, Mary, dear. 507 00:26:21,930 --> 00:26:24,565 This is my salary from the Society. 508 00:26:24,599 --> 00:26:27,368 They have nothing else with which to pay me. 509 00:26:27,402 --> 00:26:29,670 If only Mr. Hooke and Mr. Newton 510 00:26:29,672 --> 00:26:31,672 were more like you. 511 00:26:31,706 --> 00:26:33,674 DEGRASSE TYSON: Halley and Wren decided to confront Hooke 512 00:26:33,708 --> 00:26:35,342 about his false claims. 513 00:26:35,377 --> 00:26:37,962 That law is mine, I tell you! 514 00:26:38,013 --> 00:26:39,346 I proved it first. 515 00:26:39,381 --> 00:26:41,181 Then fetch your proof here at once. 516 00:26:41,216 --> 00:26:42,416 Let us see it. 517 00:26:42,450 --> 00:26:46,020 Surely we have waited on it long enough. 518 00:26:46,054 --> 00:26:49,156 You'll simply have to take my word for it. 519 00:26:49,190 --> 00:26:51,558 Empty claims may persuade elsewhere, 520 00:26:51,593 --> 00:26:53,761 but not here. 521 00:26:53,795 --> 00:26:56,397 Put up or shut up, Mr. Hooke. 522 00:26:57,799 --> 00:26:59,933 Blasted Newton. I'll make him pay. 523 00:27:15,150 --> 00:27:18,618 DEGRASSE TYSON: If it wasn't for Edmond Halley, 524 00:27:18,620 --> 00:27:20,754 Newton's great book would've never been conceived, 525 00:27:20,789 --> 00:27:23,290 nor written, nor printed. 526 00:27:23,325 --> 00:27:25,625 Okay. So what? 527 00:27:25,627 --> 00:27:27,761 What difference does that make to us? 528 00:27:27,796 --> 00:27:30,564 What's the big deal? 529 00:27:35,837 --> 00:27:38,972 When Isaac Newton was born in this house 530 00:27:39,007 --> 00:27:42,643 in 1642, the world was very different. 531 00:27:42,677 --> 00:27:44,878 Everyone looked at the perfection 532 00:27:44,913 --> 00:27:47,548 of the clockwork motions of the planets in the sky 533 00:27:47,582 --> 00:27:49,483 and could only understand it as the work 534 00:27:49,517 --> 00:27:51,151 of a master clock maker. 535 00:27:51,186 --> 00:27:53,253 How else to explain it? 536 00:27:53,288 --> 00:27:55,622 There was only one way such a thing could come about 537 00:27:55,657 --> 00:27:57,091 in their imagination; 538 00:27:57,125 --> 00:27:59,126 only one answer for them-- 539 00:27:59,160 --> 00:28:00,594 God. 540 00:28:00,628 --> 00:28:02,896 For reasons beyond our understanding, 541 00:28:02,931 --> 00:28:05,466 God just created the solar system that way. 542 00:28:05,500 --> 00:28:08,435 But this explanation is the closing of a door. 543 00:28:08,470 --> 00:28:12,005 It doesn't lead to other questions. 544 00:28:22,150 --> 00:28:23,450 Along came Newton, 545 00:28:23,485 --> 00:28:26,587 a God-loving man who's also a genius. 546 00:28:26,621 --> 00:28:28,756 He could write the laws of nature 547 00:28:28,790 --> 00:28:31,191 in perfect mathematical sentences-- 548 00:28:31,226 --> 00:28:33,660 formulas that applied universally 549 00:28:33,695 --> 00:28:36,630 to apples, moons, planets 550 00:28:36,664 --> 00:28:38,832 and so much more. 551 00:28:40,869 --> 00:28:43,704 With one foot still in the Middle Ages, 552 00:28:43,738 --> 00:28:46,974 Isaac Newton imagined the whole solar system. 553 00:28:47,008 --> 00:28:49,343 Newton's laws of gravity and motion 554 00:28:49,377 --> 00:28:53,213 revealed how the Sun held distant worlds captive. 555 00:28:53,248 --> 00:28:55,382 His laws swept away the need 556 00:28:55,400 --> 00:28:57,017 for a master clock maker 557 00:28:57,051 --> 00:29:00,487 to explain the precision and beauty of the solar system. 558 00:29:00,522 --> 00:29:03,724 Gravity is the clock maker. 559 00:29:03,758 --> 00:29:07,127 Matter obeyed commandments we could discover, 560 00:29:07,162 --> 00:29:09,730 laws the Bible hadn't mentioned. 561 00:29:09,764 --> 00:29:12,733 Newton's answer to why the solar system is the way it is 562 00:29:12,767 --> 00:29:16,303 opened the way to an infinite number of questions. 563 00:29:16,337 --> 00:29:18,338 Principia also happened to include 564 00:29:18,373 --> 00:29:20,340 the invention of calculus, 565 00:29:20,375 --> 00:29:22,976 and the first sound theoretical basis 566 00:29:23,011 --> 00:29:25,479 for an end to our imprisonment on Earth-- 567 00:29:25,513 --> 00:29:27,681 space travel. 568 00:29:31,085 --> 00:29:33,754 Newton envisioned the firing of a cannonball... 569 00:29:33,788 --> 00:29:35,522 (cannon fires) 570 00:29:35,557 --> 00:29:38,058 ...with increasingly greater explosive thrust. 571 00:29:40,528 --> 00:29:43,897 He reasoned that with enough velocity, 572 00:29:43,932 --> 00:29:46,500 the bounds of gravity could be broken, 573 00:29:46,534 --> 00:29:48,435 and the cannonball could escape 574 00:29:48,470 --> 00:29:50,771 to orbit the Earth. 575 00:29:50,805 --> 00:29:53,907 This changed everything. 576 00:30:23,238 --> 00:30:26,106 ¶ ¶ 577 00:30:46,928 --> 00:30:50,030 ¶ ¶ 578 00:30:55,837 --> 00:31:00,407 Newton's Principia Mathematica set us free in another way. 579 00:31:00,441 --> 00:31:02,309 By finding the natural laws 580 00:31:02,343 --> 00:31:05,045 governing the comings and goings of comets, 581 00:31:05,146 --> 00:31:07,247 he decoupled the motions of the heavens 582 00:31:07,282 --> 00:31:11,018 from their ancient connections to our fears. 583 00:31:13,454 --> 00:31:14,922 If Halley hadn't been standing next 584 00:31:14,956 --> 00:31:16,690 to Newton for all those years, 585 00:31:16,724 --> 00:31:18,292 perhaps the world would remember him 586 00:31:18,326 --> 00:31:21,595 for his own host of accomplishments and discoveries. 587 00:31:21,629 --> 00:31:23,864 But the only thing that comes to mind 588 00:31:23,898 --> 00:31:26,066 for most people is the comet. 589 00:31:26,100 --> 00:31:29,036 The irony is that discovering a comet 590 00:31:29,070 --> 00:31:31,271 is actually one of the few things 591 00:31:31,306 --> 00:31:33,307 that Halley never did. 592 00:31:37,912 --> 00:31:40,380 Mountain of ice to starboard! 593 00:31:40,415 --> 00:31:42,950 Come about! 594 00:31:42,952 --> 00:31:45,552 Aye, aye, Captain Halley! 595 00:31:45,587 --> 00:31:47,888 DEGRASSE TYSON: After the publication of the Principia, 596 00:31:47,922 --> 00:31:49,890 Halley was commanded by his king 597 00:31:49,924 --> 00:31:51,925 to lead three ocean voyages. 598 00:31:51,960 --> 00:31:55,062 Scientific expeditions to solve navigational problems 599 00:31:55,096 --> 00:31:57,230 for the British Navy. 600 00:31:57,265 --> 00:31:59,099 Halley used this opportunity 601 00:31:59,133 --> 00:32:02,536 to make the first map of the Earth's magnetic field. 602 00:32:06,341 --> 00:32:09,209 And he was also a businessman. 603 00:32:11,312 --> 00:32:14,047 Halley perfected the diving bell... 604 00:32:15,633 --> 00:32:17,734 ...and used his invention to start 605 00:32:17,785 --> 00:32:20,854 a flourishing commercial salvage operation. 606 00:32:25,126 --> 00:32:27,294 Mmm, ah, Dr. Halley's gone and done it this time. 607 00:32:27,328 --> 00:32:30,530 I reckon he's been down there at least three hours. 608 00:32:30,565 --> 00:32:33,266 DEGRASSE TYSON: Not one to risk the lives of others, 609 00:32:33,301 --> 00:32:36,703 Halley personally tested his own invention. 610 00:32:40,274 --> 00:32:43,844 I make it exactly four hours since our descent. 611 00:32:43,878 --> 00:32:45,979 Not at all bad for ten fathoms. 612 00:32:51,319 --> 00:32:53,253 DEGRASSE TYSON: He invented the weather map. 613 00:32:56,024 --> 00:32:59,559 And the symbols he devised for indicating prevailing winds 614 00:32:59,594 --> 00:33:02,029 are still in use today. 615 00:33:11,739 --> 00:33:14,374 Halley laid the groundwork 616 00:33:14,409 --> 00:33:16,476 for the science of population statistics. 617 00:33:16,511 --> 00:33:17,811 How? 618 00:33:17,845 --> 00:33:20,814 He compared the birth, marriage, death, 619 00:33:20,848 --> 00:33:23,717 and population densities of London and Paris. 620 00:33:23,751 --> 00:33:26,019 He actually had to pace off 621 00:33:26,054 --> 00:33:27,187 the entire perimeter of Paris, on foot, 622 00:33:27,221 --> 00:33:29,423 to learn its true dimensions. 623 00:33:29,457 --> 00:33:30,824 He came to the conclusion 624 00:33:30,858 --> 00:33:32,559 that since roughly half of all adults fail 625 00:33:32,593 --> 00:33:34,027 to reproduce children, 626 00:33:34,062 --> 00:33:36,029 who themselves survive to reproduce, 627 00:33:36,064 --> 00:33:38,932 every married couple must have four children 628 00:33:38,966 --> 00:33:41,435 in order to maintain the population. 629 00:33:44,439 --> 00:33:47,040 And it was Edmond Halley who gave us 630 00:33:47,075 --> 00:33:48,675 the actual scale of the solar system. 631 00:33:48,710 --> 00:33:51,244 He figured out a clever way to find the distance 632 00:33:51,279 --> 00:33:52,779 from Earth to the Sun. 633 00:33:52,814 --> 00:33:55,048 It involved precisely measuring the time it took 634 00:33:55,083 --> 00:33:58,418 for the planet Venus to cross the Sun's disc. 635 00:34:01,389 --> 00:34:04,191 27 years after Halley's death, 636 00:34:04,225 --> 00:34:07,561 Captain James Cook made his first voyage to Tahiti 637 00:34:07,595 --> 00:34:10,130 for the express purpose of testing Halley's method 638 00:34:10,164 --> 00:34:12,733 during a transit of Venus across the Sun. 639 00:34:12,767 --> 00:34:15,135 Using a special filter to protect his vision 640 00:34:15,169 --> 00:34:18,305 from being destroyed by looking directly at the Sun, 641 00:34:18,339 --> 00:34:21,041 Cook and his men made it possible for us to know 642 00:34:21,075 --> 00:34:25,378 that the Sun is 93 million miles from Earth. 643 00:34:25,413 --> 00:34:27,781 And Halley was the first to realize 644 00:34:27,815 --> 00:34:31,651 that the so-called "fixed" stars were not fixed at all. 645 00:34:31,686 --> 00:34:33,453 How'd he do it? 646 00:34:33,488 --> 00:34:36,056 He pored over the observations made 647 00:34:36,090 --> 00:34:38,725 by the ancient Greek astronomers of the brightest stars. 648 00:34:38,760 --> 00:34:41,461 And he compared their observations with the ones 649 00:34:41,496 --> 00:34:45,499 he himself made of the same stars 1,800 years later. 650 00:34:45,533 --> 00:34:47,768 Why hadn't anyone noticed this before? 651 00:34:47,802 --> 00:34:50,771 Halley figured out that it would only become apparent 652 00:34:50,805 --> 00:34:53,907 if you waited long enough between observations. 653 00:34:53,941 --> 00:34:56,443 It's hard to perceive the motions of things 654 00:34:56,477 --> 00:34:57,778 that are far away. 655 00:34:57,812 --> 00:35:00,480 And the stars are so very far away, 656 00:35:00,515 --> 00:35:02,816 that you would need to track them for many centuries 657 00:35:02,850 --> 00:35:06,186 before you could detect that they moved at all. 658 00:35:08,122 --> 00:35:11,758 Halley discovered the first clue to a magnificent reality: 659 00:35:11,793 --> 00:35:16,196 all the stars are in motion, streaming past each other, 660 00:35:16,230 --> 00:35:18,865 rising and falling like merry-go-round horses 661 00:35:18,900 --> 00:35:24,638 in their Newtonian dance around the center of our galaxy. 662 00:35:24,672 --> 00:35:28,875 And, oh, yes, there was that thing about the comet. 663 00:35:32,647 --> 00:35:36,116 What were those strange and beautiful celestial visitors 664 00:35:36,150 --> 00:35:38,718 that appeared without warning from time to time? 665 00:35:38,753 --> 00:35:42,823 Halley set out to solve this mystery as a detective would, 666 00:35:42,857 --> 00:35:45,158 by gathering all credible eyewitness testimony. 667 00:35:45,193 --> 00:35:47,727 The earliest precise observations of a comet 668 00:35:47,762 --> 00:35:50,630 that Halley could find were made in Constantinople 669 00:35:50,665 --> 00:35:54,968 by Nikephoros Gregoras, a Byzantine astronomer and monk 670 00:35:55,002 --> 00:35:57,237 in June 1337. 671 00:35:57,271 --> 00:36:00,540 Halley hunted down every astronomical observation 672 00:36:00,575 --> 00:36:06,413 of a comet recorded in Europe between 1472 and 1698. 673 00:36:06,447 --> 00:36:09,516 And remember, there was no such thing 674 00:36:09,550 --> 00:36:11,351 as a search engine or a computer. 675 00:36:11,385 --> 00:36:14,588 All Halley had were his books and his mind. 676 00:36:14,622 --> 00:36:16,423 Now here comes the hard part: 677 00:36:16,457 --> 00:36:19,426 Halley had to take the observations made for each comet 678 00:36:19,460 --> 00:36:23,563 and find the shape of its actual path through space. 679 00:36:23,598 --> 00:36:25,665 No one else but Newton had yet attempted 680 00:36:25,700 --> 00:36:29,002 to apply his new set of laws to an astronomical question. 681 00:36:29,036 --> 00:36:32,339 In an arduous tour de force of mathematical brilliance, 682 00:36:32,373 --> 00:36:36,710 Halley discovered that comets were bound to the Sun 683 00:36:36,744 --> 00:36:38,979 in long elliptical orbits. 684 00:36:42,783 --> 00:36:47,420 And he was the first to know that the comets seen in 1531, 685 00:36:47,455 --> 00:36:53,293 1607, and 1682... 686 00:36:53,327 --> 00:36:55,328 were one and the same-- 687 00:36:55,330 --> 00:36:58,531 a single comet that returned every 76 years. 688 00:36:58,566 --> 00:37:01,902 In a stunning example of true pattern recognition, 689 00:37:01,936 --> 00:37:04,905 he predicted it would be seen again 690 00:37:04,939 --> 00:37:07,107 more than 50 years in the future. 691 00:37:08,809 --> 00:37:11,878 For millennia, comets had been props for mystics, 692 00:37:11,913 --> 00:37:16,483 who considered them to be merely omens of human events. 693 00:37:16,517 --> 00:37:18,285 Halley shattered their monopoly, 694 00:37:18,319 --> 00:37:20,754 beating them at their own game, 695 00:37:20,788 --> 00:37:24,424 a game that no scientist had ever played before: 696 00:37:24,458 --> 00:37:26,126 prophecy. 697 00:37:26,160 --> 00:37:28,461 And he did not hedge his bet. 698 00:37:28,496 --> 00:37:30,063 Like Babe Ruth predicting 699 00:37:30,097 --> 00:37:32,899 where his next home run would land in the stands, 700 00:37:32,934 --> 00:37:35,835 Halley stated flatly that the comet would return 701 00:37:35,870 --> 00:37:40,440 at the end of 1758, from a particular part of the sky, 702 00:37:40,474 --> 00:37:42,742 following a specific path. 703 00:37:42,777 --> 00:37:45,512 There is hardly a prophecy attempted by the mystics 704 00:37:45,546 --> 00:37:48,682 that ever even strives for comparable precision. 705 00:38:06,250 --> 00:38:08,285 That's Halley's Comet. 706 00:38:08,319 --> 00:38:10,720 Out here at the edge of the solar system, 707 00:38:10,755 --> 00:38:12,122 it doesn't look like much. 708 00:38:12,156 --> 00:38:15,625 Just a big hunk of ice and rock in space. 709 00:38:15,660 --> 00:38:17,661 That's because beyond the orbit of Neptune, 710 00:38:17,695 --> 00:38:20,163 nearly five billion kilometers from the Sun, 711 00:38:20,197 --> 00:38:22,666 comets lead very quiet lives. 712 00:38:25,169 --> 00:38:28,438 As it reaches the far end of its orbit, 713 00:38:28,472 --> 00:38:31,441 it'll slow down till the Sun allows it to go no farther. 714 00:38:31,475 --> 00:38:36,146 Then it will begin its long fall back to the inner solar system. 715 00:38:36,180 --> 00:38:39,783 Halley's comet is in free fall around the Sun. 716 00:38:39,817 --> 00:38:43,153 Everything in our solar system-- the Earth, the Moon, 717 00:38:43,187 --> 00:38:45,255 the other planets, comets, asteroids, 718 00:38:45,289 --> 00:38:48,491 all of them are falling around the Sun. 719 00:38:48,526 --> 00:38:51,528 Gravity pulls the planets towards the Sun, 720 00:38:51,562 --> 00:38:53,463 but because of their orbital momentum, 721 00:38:53,497 --> 00:38:57,500 they keep moving around the Sun, never falling into it. 722 00:39:01,505 --> 00:39:03,640 Robert Hooke had died years before, 723 00:39:03,642 --> 00:39:06,443 having ruined his health with some bad habits: 724 00:39:06,477 --> 00:39:10,413 daily doses of wormwood, opium, mercury. 725 00:39:10,498 --> 00:39:13,650 A few months later, Newton was elected to replace him 726 00:39:13,652 --> 00:39:15,885 as president of the Royal Society. 727 00:39:15,920 --> 00:39:18,655 It is said that a portrait of Hooke 728 00:39:18,689 --> 00:39:21,458 once hung on these walls. 729 00:39:21,492 --> 00:39:25,995 Halley lived on to accomplish many more astonishing feats. 730 00:39:26,030 --> 00:39:30,667 He worked right up to his death at age 85. 731 00:39:30,701 --> 00:39:34,204 His final act was to call for a glass of wine. 732 00:39:34,238 --> 00:39:36,573 He downed it with pleasure... 733 00:39:36,607 --> 00:39:38,742 and breathed his last breath. 734 00:39:38,776 --> 00:39:40,443 (glass breaks) 735 00:39:43,881 --> 00:39:47,851 Some believe that it was on a night like this 736 00:39:47,885 --> 00:39:50,854 that Isaac Newton finally took his revenge 737 00:39:50,888 --> 00:39:52,722 against Robert Hooke. 738 00:40:07,271 --> 00:40:09,739 But Halley's prophecy was not forgotten. 739 00:40:09,774 --> 00:40:11,374 50 years later, 740 00:40:11,376 --> 00:40:14,010 as the time of the predicted return approached, 741 00:40:14,044 --> 00:40:15,779 the world's astronomers vied 742 00:40:15,813 --> 00:40:18,681 to be the first to catch sight of his comet. 743 00:40:18,716 --> 00:40:20,283 They weren't disappointed. 744 00:40:20,317 --> 00:40:24,554 It's been welcomed back every 76 years since. 745 00:40:24,588 --> 00:40:27,891 When Halley's Comet returns to our skies, 746 00:40:27,992 --> 00:40:31,027 sunlight will warm up the ice on its surface, 747 00:40:31,061 --> 00:40:33,029 once again setting loose 748 00:40:33,063 --> 00:40:36,900 the dust and gases trapped within. 749 00:40:38,936 --> 00:40:41,404 Halley's Comet most recently visited our neighborhood 750 00:40:41,439 --> 00:40:44,274 back in 1986. 751 00:40:44,308 --> 00:40:47,377 And if you're seeing this in 2061, 752 00:40:47,411 --> 00:40:49,345 then you'll know it's back. 753 00:40:51,916 --> 00:40:53,750 May you feel the wonder of all those 754 00:40:53,784 --> 00:40:56,152 who came before you... 755 00:40:56,187 --> 00:40:58,154 and none of the fear. 756 00:40:58,189 --> 00:41:01,791 Newton's laws made it possible for Edmond Halley 757 00:41:01,826 --> 00:41:04,494 to see some 50 years into the future 758 00:41:04,528 --> 00:41:07,497 and predict the behavior of a single comet. 759 00:41:07,531 --> 00:41:10,834 Scientists have been using these laws ever since, 760 00:41:10,868 --> 00:41:13,736 opening the way to the Moon 761 00:41:13,771 --> 00:41:16,773 and even beyond our solar system. 762 00:41:16,807 --> 00:41:19,542 The baby in the basket is learning to walk... 763 00:41:26,016 --> 00:41:28,551 ...and to know the cosmos. 764 00:41:32,656 --> 00:41:33,990 Which brings me 765 00:41:33,992 --> 00:41:35,758 to one last prophecy. 766 00:41:35,793 --> 00:41:38,928 Using nothing more than Newton's laws of gravitation, 767 00:41:38,963 --> 00:41:41,631 we astronomers can confidently predict 768 00:41:41,665 --> 00:41:43,933 that several billion years from now, 769 00:41:43,968 --> 00:41:46,669 our home galaxy, the Milky Way, 770 00:41:46,704 --> 00:41:51,007 will merge with our neighboring galaxy Andromeda. 771 00:41:52,560 --> 00:41:54,777 Because the distances between the stars 772 00:41:54,812 --> 00:41:57,146 are so great compared to their sizes, 773 00:41:57,164 --> 00:42:00,617 few if any stars in either galaxy will actually collide. 774 00:42:00,651 --> 00:42:03,586 Any life on the worlds of that far-off future 775 00:42:03,588 --> 00:42:07,524 should be safe, but they would be treated to an amazing, 776 00:42:07,558 --> 00:42:11,528 billion-year-long light show... 777 00:42:11,562 --> 00:42:15,198 a dance of a half a trillion stars... 778 00:42:15,232 --> 00:42:19,736 to music first heard on one little world 779 00:42:19,770 --> 00:42:24,507 by a man who had but one true friend. 780 00:42:55,639 --> 00:42:24,507 Captioned by Media Access Group at WGBH access.wghb.org