1 00:01:30,583 --> 00:01:32,083 "When Knowledge Conquered Fear" 2 00:01:38,932 --> 00:01:41,685 TYSON: We were born into a mystery... 3 00:01:41,852 --> 00:01:45,823 ...one that has haunted us since at least as long as we've been human. 4 00:01:48,567 --> 00:01:54,165 We awakened on this tiny world beneath a blanket of stars... 5 00:01:54,781 --> 00:01:57,625 ...like an abandoned baby left on a doorstep... 6 00:01:57,784 --> 00:02:02,665 ...without a note to explain where we came from, who we are... 7 00:02:03,165 --> 00:02:05,964 ...how our universe came to be... 8 00:02:06,126 --> 00:02:10,381 ...and with no idea how to end our cosmic isolation. 9 00:02:10,881 --> 00:02:15,227 We've had to figure it all out for ourselves. 10 00:02:19,723 --> 00:02:23,227 Best thing we had going for us was our intelligence... 11 00:02:23,393 --> 00:02:26,943 ...especially our gift for pattern recognition... 12 00:02:27,105 --> 00:02:29,233 ...sharpened over eons of evolution. 13 00:02:30,067 --> 00:02:33,071 The ones who were good at spotting prey and predator... 14 00:02:33,236 --> 00:02:35,955 ...telling poisonous plants from the nourishing ones... 15 00:02:36,114 --> 00:02:39,163 ...had a better chance to live and reproduce. 16 00:02:39,326 --> 00:02:42,751 They survived and passed on those genes for pattern recognition... 17 00:02:42,913 --> 00:02:44,915 ...with its obvious advantages. 18 00:02:45,374 --> 00:02:49,880 Cultures all over the planet looked up at the same stars... 19 00:02:50,045 --> 00:02:53,470 ...and found different pictures there. 20 00:02:59,596 --> 00:03:02,566 We used this gift for recognizing patterns in nature... 21 00:03:02,724 --> 00:03:05,978 ...to read the calendar in the sky. 22 00:03:08,146 --> 00:03:12,401 The messages written in the stars told our forefathers and mothers... 23 00:03:12,567 --> 00:03:15,491 ...when to camp and when to move on... 24 00:03:15,654 --> 00:03:19,124 ...when the migratory herds and when the rains and the cold would come... 25 00:03:19,282 --> 00:03:21,410 ...and when they would cease for a time. 26 00:03:21,576 --> 00:03:24,796 When they observed the connection between the motions of the stars... 27 00:03:24,955 --> 00:03:27,083 ...and the seasonal cycles of life on Earth... 28 00:03:27,249 --> 00:03:30,549 ...they concluded, naturally, that what happens up there... 29 00:03:30,711 --> 00:03:33,385 ...must be directed at us down here. 30 00:03:33,547 --> 00:03:35,015 It makes sense, right? 31 00:03:35,173 --> 00:03:39,428 If the sky was a calendar and somebody stuck a Post-it note on top of it... 32 00:03:39,594 --> 00:03:42,939 ...what else could it be but a message? 33 00:03:43,640 --> 00:03:46,314 And so when the heavenly order was suddenly violated... 34 00:03:46,476 --> 00:03:51,403 ...by the apparition of a comet in the sky, they took it personally. 35 00:03:51,565 --> 00:03:53,317 Can we really blame them? 36 00:03:53,483 --> 00:03:57,488 Back then, they had no other logical explanation for what was happening. 37 00:03:57,654 --> 00:04:00,578 This was long before anyone had yet to imagine Earth... 38 00:04:00,741 --> 00:04:04,666 ...as a spinning planet with a tilted axis, revolving around the sun. 39 00:04:04,828 --> 00:04:08,583 Every ancient human culture made the same mistake: 40 00:04:08,749 --> 00:04:13,505 The comet must be a message sent by the gods, or one particular god. 41 00:04:13,670 --> 00:04:20,679 And almost invariably our ancestors concluded the news was not good. 42 00:04:20,844 --> 00:04:27,853 It didn't matter if you were an ancient Aztec, Anglo-Saxon, Babylonian, Hindu. 43 00:04:28,185 --> 00:04:31,485 Comets were portents of doom. 44 00:04:31,646 --> 00:04:37,198 The only difference among them was the precise nature of the coming disaster. 45 00:04:37,360 --> 00:04:42,116 "Disaster," as in the Greek word for "bad star." 46 00:04:42,282 --> 00:04:45,707 To the Masai of East Africa, a comet meant famine. 47 00:04:45,869 --> 00:04:48,748 To the Zulu in the south, it meant war. 48 00:04:48,914 --> 00:04:52,384 To the Eghap people of the west, it meant disease. 49 00:04:52,542 --> 00:04:57,218 To the Djaga of Zaire, specifically smallpox. 50 00:04:57,380 --> 00:05:03,103 To their neighbors, the Lube, a comet foretold the death of a leader. 51 00:05:03,261 --> 00:05:06,891 The ancient Chinese were remarkably systematic. 52 00:05:07,974 --> 00:05:10,568 Starting in roughly 1400 BC... 53 00:05:10,727 --> 00:05:14,857 ...they began recording and cataloging the apparitions of comets. 54 00:05:15,023 --> 00:05:18,277 A three-tailed comet meant calamity for the state. 55 00:05:18,443 --> 00:05:22,493 A four-tailed comet signified an epidemic was coming. 56 00:05:22,656 --> 00:05:26,786 The human talent for pattern recognition is a two-edged sword. 57 00:05:26,952 --> 00:05:32,083 We're especially good at finding patterns even when they aren't really there... 58 00:05:32,249 --> 00:05:36,220 ...something known as "false pattern recognition." 59 00:05:38,880 --> 00:05:41,008 We hunger for significance... 60 00:05:41,174 --> 00:05:46,772 ...for signs that our personal existence is of special meaning to the universe. 61 00:05:48,557 --> 00:05:53,063 To that end, we're all too eager to deceive ourselves and others... 62 00:05:53,228 --> 00:05:56,277 ...to discern a sacred image in a grilled cheese sandwich... 63 00:05:56,439 --> 00:05:59,613 ...or find a divine warning in a comet. 64 00:05:59,776 --> 00:06:02,279 Today we know exactly where comets come from... 65 00:06:02,445 --> 00:06:04,948 ...and what they're made of. 66 00:06:07,450 --> 00:06:09,418 TYSON". Our Ship of the Imagination... 67 00:06:09,578 --> 00:06:13,128 ...fueled by equal parts of science and wonder... 68 00:06:13,290 --> 00:06:17,090 ...can take us anywhere in space and time. 69 00:06:17,252 --> 00:06:18,925 It can travel faster than light... 70 00:06:19,087 --> 00:06:22,808 ...and render visible those things that cannot be seen. 71 00:06:22,966 --> 00:06:28,689 It's carrying us to a mysterious realm that lies one light-year from the sun. 72 00:06:28,847 --> 00:06:31,145 What is this swarm of worlds? 73 00:06:31,308 --> 00:06:33,652 Was it organized by alien beings? 74 00:06:33,810 --> 00:06:36,438 No, just gravity. 75 00:06:36,605 --> 00:06:38,983 These are the snows of yesteryear. 76 00:06:39,149 --> 00:06:41,948 Drifting mountains of ice and rock. 77 00:06:42,110 --> 00:06:44,989 The preserved remnants of the birth of the solar system. 78 00:06:45,155 --> 00:06:48,534 It's called the Oort cloud, after Jan Oort... 79 00:06:48,700 --> 00:06:53,251 ...the Dutch astronomer who foretold its existence back in 1950. 80 00:06:53,413 --> 00:06:55,586 He was trying to solve a paradox. 81 00:06:55,749 --> 00:06:59,003 There's so many ways for comets to die. 82 00:06:59,169 --> 00:07:03,515 Because they cross the orbits of planets, comets frequently collide with them. 83 00:07:04,507 --> 00:07:08,307 Comets are largely made of ice, so every time they come near the sun... 84 00:07:08,470 --> 00:07:11,474 ...they lose a part of themselves through evaporation. 85 00:07:11,640 --> 00:07:15,816 And after several thousand trips, their ice is all gone... 86 00:07:15,977 --> 00:07:18,696 ...and what remains of the comet is now an asteroid. 87 00:07:18,855 --> 00:07:21,825 Comets can be gravitationally ejected from the solar system... 88 00:07:21,983 --> 00:07:23,576 ...and exiled into space. 89 00:07:23,735 --> 00:07:27,660 And yet somehow the comets keep coming. 90 00:07:27,822 --> 00:07:32,043 Oort and other astronomers wondered, "Where do all the comets come from?" 91 00:07:34,412 --> 00:07:37,291 Oort calculated the rate at which new comets appear... 92 00:07:37,457 --> 00:07:41,507 ...and concluded that there must be a vast spherical swarm of them... 93 00:07:41,670 --> 00:07:45,766 ...a few light-years across, surrounding the sun. 94 00:07:48,969 --> 00:07:50,892 Oort's logic still holds up... 95 00:07:51,054 --> 00:07:53,807 ...even after all the discoveries we've made about comets... 96 00:07:53,974 --> 00:07:56,648 ...and the solar system in the many decades since. 97 00:07:56,810 --> 00:08:02,533 And yet the Oort cloud is a sight that no one has ever seen. 98 00:08:02,941 --> 00:08:05,945 Nor could we. It's dark out here. 99 00:08:06,111 --> 00:08:09,115 And each comet is about as far from its closest neighbor... 100 00:08:09,280 --> 00:08:11,157 ...as the Earth is from Saturn. 101 00:08:11,324 --> 00:08:14,578 But science gives us special powers of our own. 102 00:08:14,744 --> 00:08:18,339 It gave Jan Oort the gift of prophecy. 103 00:08:18,498 --> 00:08:21,047 Oort was also the first to correctly estimate... 104 00:08:21,209 --> 00:08:24,258 ...the distance between the sun and the center of our galaxy. 105 00:08:24,921 --> 00:08:28,596 That's a big deal, finding out where we are in the Milky Way. 106 00:08:28,758 --> 00:08:33,104 Our star is about 30,000 light-years from the center. 107 00:08:33,263 --> 00:08:35,937 Oort was also the first guy to use a radio telescope... 108 00:08:36,099 --> 00:08:38,397 ...to map the galaxy's spiral structure. 109 00:08:38,977 --> 00:08:44,859 And he discovered that the center of our galaxy was a place of titanic explosions... 110 00:08:45,025 --> 00:08:47,374 ...the first indication that there might have 111 00:08:47,386 --> 00:08:49,747 been a supermassive black hole lurking there. 112 00:08:49,904 --> 00:08:52,953 Does the fact that most of us know the names of mass murderers... 113 00:08:53,116 --> 00:08:57,747 ...but have never heard of Jan Oort, say anything about us? 114 00:09:06,880 --> 00:09:08,974 The Oort cloud is so enormous... 115 00:09:09,132 --> 00:09:12,102 ...that it takes one of its comets about a million years... 116 00:09:12,260 --> 00:09:15,935 ...to complete a single trip around the sun. 117 00:09:17,974 --> 00:09:20,602 Out here at the far edge of the solar system... 118 00:09:20,769 --> 00:09:23,864 ...even a little tug from the gravity of a passing star... 119 00:09:24,022 --> 00:09:29,370 ...can liberate some of these comets from their gravitational bondage to the sun. 120 00:09:32,655 --> 00:09:37,001 Some comets are flung out of the solar system to wander interstellar space. 121 00:09:37,160 --> 00:09:40,790 But for others there's a different fate. 122 00:09:47,003 --> 00:09:51,850 This one is plunging towards the sun, gaining speed in an unbroken free fall... 123 00:09:52,008 --> 00:09:55,262 ...that lasts hundreds of thousands of years. 124 00:09:56,096 --> 00:10:02,024 When Neptune's gravity gives it another tug, there's a small change in course. 125 00:10:02,185 --> 00:10:06,235 Mighty Jupiter, the most massive object in our solar system other than the sun... 126 00:10:06,397 --> 00:10:09,742 ...attracts the comet with its powerful gravitational pull... 127 00:10:09,901 --> 00:10:12,370 ...bending its path. 128 00:10:15,323 --> 00:10:19,544 When our comet reaches the inner solar system... 129 00:10:20,995 --> 00:10:24,625 ...heat from the sun bakes it. 130 00:10:32,340 --> 00:10:35,594 A beautiful transformation begins. 131 00:10:35,760 --> 00:10:41,062 The barren, sooty iceberg now sports a glowing halo... 132 00:10:41,891 --> 00:10:43,893 ...and a tail. 133 00:10:50,733 --> 00:10:53,703 These layers tell the story of how the comet was made... 134 00:10:53,862 --> 00:10:56,991 ...some 4 billion years ago. 135 00:11:01,286 --> 00:11:04,256 During the 40,000 generations of humanity... 136 00:11:04,414 --> 00:11:09,716 ...there must have been roughly 100,000 apparitions of a bright comet. 137 00:11:10,211 --> 00:11:15,593 For all that time, the best we could do was look up in helpless wonder... 138 00:11:15,758 --> 00:11:18,932 ...prisoners of Earth with nowhere to turn for an explanation... 139 00:11:19,095 --> 00:11:22,019 ...beyond our guilt and our fears. 140 00:11:22,932 --> 00:11:26,106 But then a friendship began between two men... 141 00:11:26,269 --> 00:11:30,149 ...that led to a permanent revolution in human thought. 142 00:11:31,149 --> 00:11:34,244 Isaac Newton and Edmond Halley could not know it... 143 00:11:34,402 --> 00:11:37,781 ...but their collaboration would ultimately set us free... 144 00:11:37,947 --> 00:11:42,623 ...from our long confinement on this tiny world. 145 00:11:48,958 --> 00:11:53,714 TYSON: The comet of 1664 sent shivers of dread throughout Europe. 146 00:11:53,880 --> 00:11:56,099 And the terror seemed justified... 147 00:11:56,257 --> 00:11:59,978 ...when the plague and the Great Fire of London followed soon after. 148 00:12:01,429 --> 00:12:04,683 WOMAN: There, with long bloody hair... 149 00:12:04,849 --> 00:12:08,524 ...a blazing star threatens the world... 150 00:12:08,686 --> 00:12:13,658 ...with famine, plague and war. 151 00:12:14,525 --> 00:12:17,699 To princes, it spells death. 152 00:12:18,321 --> 00:12:21,450 To kingdoms, many crosses. 153 00:12:22,825 --> 00:12:25,999 To all estates, inevitable losses. 154 00:12:26,871 --> 00:12:28,839 To herdsmen, rot. 155 00:12:28,998 --> 00:12:31,501 To plowmen, hapless seasons. 156 00:12:32,585 --> 00:12:36,089 To sailors, it brings storms. 157 00:12:37,632 --> 00:12:41,682 To cities, civil treasons. 158 00:12:47,517 --> 00:12:48,814 TYSON". But for one child... 159 00:12:49,686 --> 00:12:52,690 ...the comet was not the least bit frightening. 160 00:12:57,694 --> 00:13:01,198 For him, it was a thing of wonder. 161 00:13:01,364 --> 00:13:05,244 Like all of us, Edmond Halley was born curious. 162 00:13:05,410 --> 00:13:07,128 Hell's bells. 163 00:13:07,996 --> 00:13:12,001 TYSON: He was lucky to have a father who encouraged and nurtured his curiosity... 164 00:13:12,166 --> 00:13:14,265 ...buying him the best scientific instruments, 165 00:13:14,277 --> 00:13:16,387 and even funding his expedition... 166 00:13:16,546 --> 00:13:20,221 ...to make the first accurate star map of the Southern Hemisphere. 167 00:13:20,383 --> 00:13:24,229 Halley dropped out of Oxford when he was 20 and sailed to St. Helena... 168 00:13:24,387 --> 00:13:27,311 ...an island below the equator, off the west coast of Africa. 169 00:13:33,730 --> 00:13:36,074 Hell's bells. 170 00:13:36,232 --> 00:13:39,406 TYSON: Problem was, nobody told Halley that the weather on St. Helena... 171 00:13:39,569 --> 00:13:43,369 ...was generally lousy. It took him 12 frustrating months... 172 00:13:43,531 --> 00:13:48,082 ...to observe enough southern stars to make a complete map. 173 00:13:48,870 --> 00:13:50,964 The gods and heroes of ancient Greece... 174 00:13:51,122 --> 00:13:55,298 ...were now joined by the mythic figures of a new world and age: 175 00:13:55,460 --> 00:14:00,387 a toucan, a compass, a bird of paradise. 176 00:14:08,306 --> 00:14:10,934 When Halley came home with the other half of the sky... 177 00:14:11,100 --> 00:14:13,228 ...his map created a sensation. 178 00:14:13,394 --> 00:14:16,193 Now merchants and explorers could navigate by the stars... 179 00:14:16,356 --> 00:14:18,074 ...visible anywhere on Earth. 180 00:14:18,232 --> 00:14:20,451 At the time, the Royal Society of London... 181 00:14:20,610 --> 00:14:23,363 ...was the world's clearinghouse of scientific discovery. 182 00:14:23,529 --> 00:14:28,911 Its motto, "Nullius in verba," sums up the heart of the scientific method. 183 00:14:29,077 --> 00:14:31,921 It's Latin for "see for yourself." 184 00:14:32,080 --> 00:14:35,584 In other words, question authority. 185 00:14:35,750 --> 00:14:39,800 Halley's star maps caught the attention of the Society's curator of experiments. 186 00:14:39,962 --> 00:14:42,226 I'd show him to you if I could, but no portrait 187 00:14:42,238 --> 00:14:44,513 of Robert Hooke exists from his time... 188 00:14:44,675 --> 00:14:47,303 ...only the verbal descriptions of his contemporaries. 189 00:14:47,470 --> 00:14:50,644 They called him "lean, bent, ugly." 190 00:14:50,807 --> 00:14:53,981 He was possibly the most inventive person who ever lived. 191 00:14:54,143 --> 00:14:58,899 And despite his appearance, he was the most sought-after party guest in all of London. 192 00:14:59,065 --> 00:15:05,823 Why? Hooke's insatiable curiosity encompassed absolutely everything. 193 00:15:07,240 --> 00:15:09,743 Hooke discovered a little cosmos... 194 00:15:09,909 --> 00:15:14,164 ...and we still call it by the name he gave it: the cell. 195 00:15:14,330 --> 00:15:16,429 Hooke discovered the cell by looking at a 196 00:15:16,441 --> 00:15:18,551 piece of cork with one of his own inventions: 197 00:15:18,709 --> 00:15:20,336 the compound microscope. 198 00:15:20,962 --> 00:15:26,765 He anticipated aspects of Darwin's theory of evolution by almost 200 years. 199 00:15:26,926 --> 00:15:28,849 Hooke also improved the telescope. 200 00:15:29,011 --> 00:15:31,890 The drawings he made of the astronomical bodies he observed... 201 00:15:32,056 --> 00:15:34,400 ...attest to his uncanny precision. 202 00:15:34,559 --> 00:15:38,530 After the Great Fire destroyed central London in 1666... 203 00:15:38,688 --> 00:15:41,316 ...Hooke partnered with the architect Christopher Wren... 204 00:15:41,482 --> 00:15:43,155 ...to redesign and rebuild the city. 205 00:15:43,901 --> 00:15:48,031 Hooke was the foremost experimentalist of his age. 206 00:15:48,197 --> 00:15:51,576 Using coiled springs, he derived the law of elasticity... 207 00:15:51,742 --> 00:15:54,461 ...known today as Hooke's law. 208 00:15:54,620 --> 00:15:58,500 He perfected the air pump, the height of technology in its time... 209 00:15:58,666 --> 00:16:02,512 ...and used it to experiment on respiration and sound. 210 00:16:02,670 --> 00:16:05,423 And he experimented with cannabis. 211 00:16:05,590 --> 00:16:07,843 He reported to a meeting of the Royal Society... 212 00:16:08,009 --> 00:16:12,765 ...that a sea captain friend of his, quote, "had so often experimented with it... 213 00:16:12,930 --> 00:16:18,482 ...that there is no cause of fear, though possibly there may be of laughter." 214 00:16:22,106 --> 00:16:26,361 But coffee was the drug of choice for England in the 17th century. 215 00:16:26,527 --> 00:16:29,121 Coffeehouses sprang up all over London. 216 00:16:29,280 --> 00:16:30,623 [INAUDIBLE DIALOGUE] 217 00:16:41,292 --> 00:16:43,761 This is where people came to get news... 218 00:16:43,920 --> 00:16:46,764 ...to launch new ventures, and to debate ideas. 219 00:16:47,256 --> 00:16:52,763 The coffeehouse was an oasis of equality in a class-obsessed society. 220 00:16:53,262 --> 00:16:58,063 Here a poor man needn't give up his seat to a rich man, nor submit to his opinion. 221 00:16:58,226 --> 00:17:00,604 It was a kind of laboratory of democracy. 222 00:17:01,229 --> 00:17:03,277 In this highly caffeinated atmosphere... 223 00:17:04,065 --> 00:17:08,662 ...Halley and Hooke met Christopher Wren to discuss a deep mystery: 224 00:17:08,819 --> 00:17:11,823 Why do the planets move as they do? 225 00:17:11,989 --> 00:17:15,539 The astronomer Johannes Kepler had demonstrated some 80 years before... 226 00:17:16,077 --> 00:17:18,421 ...that the orbits of the planets around the sun... 227 00:17:18,579 --> 00:17:21,753 ...were not perfect circles, but actually ellipses... 228 00:17:21,916 --> 00:17:27,764 ...and that the closer a planet was to the sun, the faster it moved. 229 00:17:28,714 --> 00:17:31,456 Why? Could some invisible force from the sun 230 00:17:31,468 --> 00:17:34,221 be responsible for this change in motion? 231 00:17:34,387 --> 00:17:36,264 If so, how did it work? 232 00:17:36,430 --> 00:17:39,309 Could there be a simple mathematical law to describe it? 233 00:17:39,475 --> 00:17:43,230 Maybe something like Hooke's law of elasticity? 234 00:17:47,275 --> 00:17:48,492 Perhaps. 235 00:17:48,651 --> 00:17:52,872 But try as he might, Christopher Wren couldn't figure it out. 236 00:17:53,030 --> 00:17:55,783 Damned if I haven't tried. It's beyond me. 237 00:17:55,950 --> 00:17:59,329 I'll wager a book worth 40 shillings to the man who can solve it. 238 00:17:59,495 --> 00:18:02,999 HOOKE: That book is mine, Mr. Wren. I've already done the calculation. 239 00:18:03,165 --> 00:18:04,257 TYSON". Halley was delighted. 240 00:18:04,417 --> 00:18:05,964 Show us, Mr. Hooke. 241 00:18:06,127 --> 00:18:09,472 TYSON". But months passed, and Hooke failed to deliver. 242 00:18:09,630 --> 00:18:11,348 He couldn't do the math. 243 00:18:11,507 --> 00:18:12,633 None of them could. 244 00:18:12,800 --> 00:18:15,724 Finally Halley had enough of Hooke's excuses. 245 00:18:15,886 --> 00:18:20,642 Halley knew there must be someone, somewhere, up to the challenge. 246 00:18:27,356 --> 00:18:30,200 What about that mathematician at Cambridge? 247 00:18:30,359 --> 00:18:31,702 He was a clever fellow. 248 00:18:31,861 --> 00:18:35,456 He had solved central questions about the nature of light years before... 249 00:18:35,615 --> 00:18:37,709 ...when he was still only 22. 250 00:18:37,867 --> 00:18:40,370 And he invented the reflecting telescope. 251 00:18:40,536 --> 00:18:43,710 Odd bird. Dropped out of sight a while back. 252 00:18:43,873 --> 00:18:47,047 Some squabble over Hooke and his discovery about light. 253 00:18:47,209 --> 00:18:51,009 Went completely to pieces over it, has been hiding out in Cambridge ever since. 254 00:18:51,172 --> 00:18:55,803 Halley wondered if this strange and, by all accounts, exceedingly difficult man... 255 00:18:55,968 --> 00:18:58,972 ...might succeed where Hooke and others had failed. 256 00:18:59,138 --> 00:19:02,859 What he couldn't know, what no one could possibly imagine at the time... 257 00:19:03,017 --> 00:19:07,067 ...were the countless ways the world would be forever changed by this meeting... 258 00:19:07,229 --> 00:19:11,154 ...on an August day in 1684. 259 00:19:19,283 --> 00:19:23,584 TYSON: Isaac Newton was born in England on Christmas Day in 1642. 260 00:19:23,746 --> 00:19:25,293 [PANTING] 261 00:19:25,456 --> 00:19:29,586 TYSON: Before he even opened his eyes, his father was already dead. 262 00:19:31,671 --> 00:19:36,097 His mother left him when he was only 3 and did not return until he was 11 . 263 00:19:36,258 --> 00:19:37,885 [CHILDREN CHATTERING] 264 00:19:38,052 --> 00:19:41,101 TYSON: When she did, it was with a new family and husband... 265 00:19:41,263 --> 00:19:45,359 ...a stepfather who Isaac Newton despised. 266 00:19:49,397 --> 00:19:52,241 Newton's refuge from his miserable family life... 267 00:19:52,400 --> 00:19:55,870 ...was his passion to understand how things worked... 268 00:19:56,028 --> 00:19:59,202 ...especially nature itself. 269 00:19:59,365 --> 00:20:04,713 In 1661 the talented young Isaac entered Trinity College at Cambridge University... 270 00:20:04,870 --> 00:20:08,249 ...where he was a consistently lousy student... 271 00:20:08,416 --> 00:20:13,297 ...one without friends or a loving family to provide any warmth or encouragement. 272 00:20:13,462 --> 00:20:16,966 Newton mostly kept to himself, sequestered in his room... 273 00:20:17,133 --> 00:20:21,639 ...studying ancient Greek philosophers, geometry and languages... 274 00:20:21,804 --> 00:20:28,312 ...and pondering deep questions on the nature of matter, space, time and motion. 275 00:20:28,644 --> 00:20:32,740 This budding scientist was also a passionate mystic. 276 00:20:32,898 --> 00:20:35,993 Newton believed that a secret knowledge called alchemy... 277 00:20:36,152 --> 00:20:39,452 ...known only to a small group of ancient philosophers... 278 00:20:39,613 --> 00:20:41,286 ...was waiting to be rediscovered. 279 00:20:41,991 --> 00:20:46,497 He hoped to learn how to change ordinary metals into silver and gold... 280 00:20:46,662 --> 00:20:51,964 ...and maybe even cook up the elixir of life, the key to immortality. 281 00:20:53,210 --> 00:20:58,216 He was also obsessed with finding hidden messages in the words of the Bible. 282 00:20:59,592 --> 00:21:02,892 He combed through translations in several different languages... 283 00:21:03,053 --> 00:21:07,854 ...hoping to decipher coded instructions from God. 284 00:21:12,688 --> 00:21:17,319 He made elaborate calculations in an effort to discover the date of the Second Coming. 285 00:21:19,361 --> 00:21:25,619 His lifelong research in alchemy and biblical chronology never led anywhere. 286 00:21:29,413 --> 00:21:36,217 When Halley found Newton that fateful day, he was living as a virtual recluse. 287 00:21:38,756 --> 00:21:42,056 Newton had gone into hiding 13 years earlier... 288 00:21:42,218 --> 00:21:44,892 ...after Robert Hooke had publicly accused Newton... 289 00:21:45,054 --> 00:21:48,854 ...of stealing his groundbreaking work on light and color. 290 00:21:49,016 --> 00:21:53,613 In fact, it was Isaac Newton who solved the mystery of the spectrum of light... 291 00:21:53,771 --> 00:21:55,739 ...not Robert Hooke. 292 00:21:55,898 --> 00:21:57,821 The wound was painful and deep... 293 00:21:57,983 --> 00:22:00,452 ...and Newton resolved to never expose himself... 294 00:22:00,611 --> 00:22:04,206 ...to that kind of public humiliation ever again. 295 00:22:04,365 --> 00:22:08,120 Sir, I don't suppose you recall our meeting a few years ago? 296 00:22:08,285 --> 00:22:10,003 Yes, Mr. Halley. 297 00:22:10,162 --> 00:22:11,664 I'm sorry to bother you. 298 00:22:11,831 --> 00:22:14,380 Never mind the formalities. Get to your point. 299 00:22:14,542 --> 00:22:17,591 I've been talking with our friends Mr. Wren and Mr. Hooke. 300 00:22:17,753 --> 00:22:20,677 That scoundrel Hooke's no friend of mine. 301 00:22:20,840 --> 00:22:22,467 Yes, I understand, sir. 302 00:22:22,633 --> 00:22:27,434 But the thing is, we've been debating the puzzling question of planetary motion. 303 00:22:27,596 --> 00:22:29,820 We all agree that some force of attraction from 304 00:22:29,832 --> 00:22:32,067 the sun governs the motions of the planets. 305 00:22:32,226 --> 00:22:34,979 We suspect there must be a mathematical law... 306 00:22:35,145 --> 00:22:38,740 ...to describe how this force changes with distance. 307 00:22:38,899 --> 00:22:40,242 And knowing of your skill-- 308 00:22:40,401 --> 00:22:44,122 Yes, yes, the attraction of gravity weakens with the square of the distance. 309 00:22:44,280 --> 00:22:46,624 That's why the planets move in ellipses. 310 00:22:46,782 --> 00:22:49,285 But, sir, how can you know this? 311 00:22:49,451 --> 00:22:52,204 Why, I have calculated it some five years ago. 312 00:22:52,371 --> 00:22:55,090 I beg you, show it to me. 313 00:22:55,249 --> 00:22:58,469 The calculation is here somewhere. 314 00:22:58,627 --> 00:23:02,097 Well, no matter. I shall redo it and be sure to send it on to you. 315 00:23:02,256 --> 00:23:06,978 This is stupendous. Why have we not had word of it before? 316 00:23:07,136 --> 00:23:10,310 TYSON: Newton remembered all too well what Hooke had done to him... 317 00:23:10,472 --> 00:23:13,601 ...the last time he put forth an idea. 318 00:23:14,101 --> 00:23:16,103 Just when Halley may have begun to wonder... 319 00:23:16,270 --> 00:23:19,149 ...if Newton was bluffing, as Hooke had done earlier... 320 00:23:19,315 --> 00:23:22,785 ...a messenger arrived with an envelope from Newton. 321 00:23:26,155 --> 00:23:29,830 Here are the opening pages of modern science... 322 00:23:30,367 --> 00:23:32,620 ...with its all-embracing vision of nature... 323 00:23:33,203 --> 00:23:37,299 ...universal laws of motion, gravity... 324 00:23:37,458 --> 00:23:42,259 ...not just for the Earth but for the cosmos. 325 00:23:42,421 --> 00:23:44,423 Halley raced back to Cambridge. 326 00:23:44,590 --> 00:23:47,594 Mr. Newton, I beseech you to work all of this 327 00:23:47,760 --> 00:23:49,979 into a book as soon as possible. 328 00:23:50,137 --> 00:23:53,482 I can assure you the Royal Society will publish it. 329 00:23:53,641 --> 00:23:55,359 TYSON". But there was one little problem. 330 00:23:56,268 --> 00:24:01,024 We are in agreement that Mr. Newton has produced a masterpiece. 331 00:24:01,190 --> 00:24:04,694 However, I'm afraid the Royal Society has... 332 00:24:04,860 --> 00:24:08,831 Well, regrettably, sales for the History of Fish... 333 00:24:08,989 --> 00:24:12,539 ...have not lived up to our financial expectations. 334 00:24:14,036 --> 00:24:15,379 TYSON". It's an impressive book. 335 00:24:15,537 --> 00:24:19,542 Extremely comprehensive, really. 336 00:24:19,708 --> 00:24:25,010 It's filled with lavish illustrations of, well, fish. 337 00:24:26,340 --> 00:24:29,219 The disappointing sales led to a bigger problem. 338 00:24:29,385 --> 00:24:32,024 The Royal Society pretty much blew its total 339 00:24:32,036 --> 00:24:34,687 annual budget on the History of Fish. 340 00:24:34,848 --> 00:24:37,442 In fact, they were so strapped for cash... 341 00:24:37,601 --> 00:24:42,402 ...they had to pay poor Halley's salary with copies of their worst-selling book. 342 00:24:42,564 --> 00:24:45,408 With no money to print Newton's Principia... 343 00:24:45,567 --> 00:24:49,322 ...the scientific revolution hung in the balance. 344 00:24:53,909 --> 00:24:55,752 Without Halley's heroic efforts... 345 00:24:55,911 --> 00:25:00,462 ...the reclusive Newton's masterwork might never have seen the light of day. 346 00:25:00,624 --> 00:25:02,422 But Halley was a man on a mission... 347 00:25:02,584 --> 00:25:06,054 ...absolutely determined to bring Newton's genius to the world. 348 00:25:06,797 --> 00:25:11,098 That pre-scientific world, the world ruled by fear... 349 00:25:11,260 --> 00:25:14,434 ...was poised at the edge of a revolution. 350 00:25:14,596 --> 00:25:17,440 Everything depended on whether or not Edmond Halley... 351 00:25:17,599 --> 00:25:20,694 ...could get Newton's book out to the wider world. 352 00:25:20,853 --> 00:25:23,527 Halley resolved not only to edit Newton's book... 353 00:25:23,689 --> 00:25:26,442 ...but to publish it at his own expense. 354 00:25:26,608 --> 00:25:29,077 Newton completed the first two volumes... 355 00:25:29,236 --> 00:25:33,207 ...laying the mathematical framework for the physics of motion. 356 00:25:33,365 --> 00:25:37,836 The third volume would settle once and for all who won the coffeehouse wager. 357 00:25:37,995 --> 00:25:42,171 Newton applied his principles to explain all the known motions of the Earth... 358 00:25:42,332 --> 00:25:44,801 ...the moon and the planets. 359 00:25:44,960 --> 00:25:47,964 Unfortunately, there was this problem. 360 00:25:48,130 --> 00:25:52,636 Now Halley also took on the role of Newton's psychotherapist. 361 00:25:53,469 --> 00:25:55,471 Isaac, I'm afraid that Mr. Hooke... 362 00:25:55,637 --> 00:25:59,392 ...requires an acknowledgment in the preface of your third volume. 363 00:25:59,558 --> 00:26:02,937 But I have done so, thanking him, Mr. Wren and yourself... 364 00:26:03,103 --> 00:26:05,982 ...for prodding me to think again on astronomical matters. 365 00:26:06,148 --> 00:26:08,526 Mr. Hooke has been going about London... 366 00:26:08,692 --> 00:26:11,662 ...saying that you got the law of gravity from him. 367 00:26:11,820 --> 00:26:13,697 Why, that litigious little... 368 00:26:13,864 --> 00:26:18,495 Never. I would sooner burn the third volume than deface it with such a lie. 369 00:26:18,660 --> 00:26:19,957 To hell with Hooke. 370 00:26:20,120 --> 00:26:23,670 He will be long forgotten when your ideas are still being celebrated. 371 00:26:26,210 --> 00:26:29,589 More copies of that dreadful book? 372 00:26:29,755 --> 00:26:32,304 Wherever shall we put them all? 373 00:26:32,466 --> 00:26:34,139 We talked about this, Mary, dear. 374 00:26:34,301 --> 00:26:36,474 This is my salary from the Society. 375 00:26:36,637 --> 00:26:39,265 They have nothing else with which to pay me. 376 00:26:39,431 --> 00:26:43,686 If only Mr. Hooke and Mr. Newton were more like you. 377 00:26:43,852 --> 00:26:47,197 TYSON". Halley and Wren decided to confront Hooke about his false claims. 378 00:26:47,856 --> 00:26:49,858 That law is mine, I tell you. 379 00:26:50,025 --> 00:26:51,277 I proved it first. 380 00:26:51,443 --> 00:26:53,366 Then fetch your proof here at once. 381 00:26:53,529 --> 00:26:57,909 Let us see it. Surely we have waited on it long enough. 382 00:26:58,325 --> 00:27:01,044 You'll simply have to take my word for it. 383 00:27:01,203 --> 00:27:05,709 Empty claims may persuade elsewhere, but not here. 384 00:27:05,874 --> 00:27:08,343 Put up or shut up, Mr. Hooke. 385 00:27:09,378 --> 00:27:11,847 Blasted Newton. I'll make him pay. 386 00:27:28,647 --> 00:27:30,524 TYSON". If it wasn't for Edmond Halley... 387 00:27:30,691 --> 00:27:35,697 ...Newton's great book would've never been conceived, nor written, nor printed. 388 00:27:35,863 --> 00:27:40,369 Okay, but so what? What difference does that make to us? 389 00:27:40,534 --> 00:27:42,457 What's the big deal? 390 00:27:49,084 --> 00:27:54,932 When Isaac Newton was born in this house in 1642, the world was very different. 391 00:27:55,090 --> 00:27:57,331 Everyone looked at the perfection of the 392 00:27:57,343 --> 00:27:59,596 clockwork motions of the planets in the sky... 393 00:27:59,761 --> 00:28:03,561 ...and could only understand it as the work of a master clockmaker. 394 00:28:03,724 --> 00:28:05,226 How else to explain it? 395 00:28:05,392 --> 00:28:09,272 There was only one way such a thing could come about in their imagination. 396 00:28:09,438 --> 00:28:12,533 Only one answer for them: God. 397 00:28:12,691 --> 00:28:17,663 For reasons beyond our understanding, God just created the solar system that way. 398 00:28:17,821 --> 00:28:20,950 But this explanation is the closing of a door. 399 00:28:21,116 --> 00:28:23,960 It doesn't lead to other questions. 400 00:28:34,129 --> 00:28:39,135 Along came Newton, a God-loving man who's also a genius. 401 00:28:39,301 --> 00:28:43,602 He could write the laws of nature in perfect mathematical sentences. 402 00:28:43,764 --> 00:28:50,773 Formulas that applied universally to apples, moons, planets and so much more. 403 00:28:53,523 --> 00:28:55,992 With one foot still in the Middle Ages... 404 00:28:56,151 --> 00:28:59,325 ...Isaac Newton imagined the whole solar system. 405 00:28:59,488 --> 00:29:02,588 Newton's laws of gravity and motion revealed 406 00:29:02,600 --> 00:29:05,712 how the sun held distant worlds captive. 407 00:29:05,869 --> 00:29:08,998 His laws swept away the need for a master clockmaker... 408 00:29:09,164 --> 00:29:12,919 ...to explain the precision and beauty of the solar system. 409 00:29:13,085 --> 00:29:15,634 Gravity is the clockmaker. 410 00:29:16,421 --> 00:29:19,174 Matter obeyed commandments we could discover... 411 00:29:19,341 --> 00:29:21,810 ...laws the Bible hadn't mentioned. 412 00:29:21,969 --> 00:29:25,269 Newton's answer to why the solar system is the way it is... 413 00:29:25,430 --> 00:29:28,183 ...opened the way to an infinite number of questions. 414 00:29:28,725 --> 00:29:32,355 Principia also happened to include the invention of calculus... 415 00:29:32,521 --> 00:29:37,823 ...and the first sound theoretical basis for an end to our imprisonment on Earth: 416 00:29:37,985 --> 00:29:39,612 space travel. 417 00:29:43,365 --> 00:29:47,336 Newton envisioned the firing of a cannonball... 418 00:29:47,494 --> 00:29:51,419 ...with increasingly greater explosive thrust. 419 00:29:53,208 --> 00:29:55,711 He reasoned that with enough velocity... 420 00:29:55,877 --> 00:29:58,596 ...the bounds of gravity could be broken... 421 00:29:58,755 --> 00:30:02,805 ...and the cannonball could escape to orbit the Earth. 422 00:30:02,968 --> 00:30:05,847 This changed everything. 423 00:30:17,983 --> 00:30:19,576 [MAN SPEAKS INDISTINCTLY OVER RADIO] 424 00:31:07,783 --> 00:31:12,129 TYSON: Newton's Principia Mathematica set us free in another way. 425 00:31:12,287 --> 00:31:16,713 By finding the natural laws governing the comings and goings of comets... 426 00:31:16,875 --> 00:31:19,298 ...he decoupled the motions of the heavens... 427 00:31:19,461 --> 00:31:23,967 ...from their ancient connections to our fears. 428 00:31:28,970 --> 00:31:32,474 If Halley hadn't been standing next to Newton for all those years... 429 00:31:32,641 --> 00:31:34,609 ...perhaps the world would remember him... 430 00:31:34,768 --> 00:31:37,487 ...for his own host of accomplishments and discoveries. 431 00:31:37,646 --> 00:31:41,867 But the only thing that comes to mind for most people is the comet. 432 00:31:42,025 --> 00:31:44,995 The irony is that discovering a comet... 433 00:31:45,153 --> 00:31:48,999 ...is actually one of the few things that Halley never did. 434 00:31:54,037 --> 00:31:56,005 Mountain of ice to starboard. 435 00:31:56,164 --> 00:31:58,508 Come about. Come about! 436 00:31:58,667 --> 00:32:01,170 MAN: Aye, aye, Captain Halley! 437 00:32:01,336 --> 00:32:03,509 TYSON: After the publication of the Principia... 438 00:32:04,005 --> 00:32:07,600 ...Halley was commanded by his king to lead three ocean voyages... 439 00:32:08,093 --> 00:32:12,519 ...scientific expeditions to solve navigational problems for the British navy. 440 00:32:12,681 --> 00:32:18,188 Halley used this opportunity to make the first map of the Earth's magnetic field. 441 00:32:18,353 --> 00:32:20,355 [THUNDER RUMBLING] 442 00:32:22,107 --> 00:32:24,860 TYSON: And he was also a businessman. 443 00:32:27,487 --> 00:32:30,536 Halley perfected the diving bell... 444 00:32:31,700 --> 00:32:36,206 ...and used his invention to start a flourishing commercial salvage operation. 445 00:32:40,834 --> 00:32:43,178 Hmm. Our Dr. Halley's gone and done it this time. 446 00:32:43,336 --> 00:32:46,215 I reckon he's been down there at least three hours. 447 00:32:46,381 --> 00:32:53,230 TYSON: Not one to risk the lives of others, Halley personally tested his own invention. 448 00:32:56,516 --> 00:32:59,690 I make it exactly four hours since our descent. 449 00:32:59,853 --> 00:33:01,651 Not at all bad for 10 fathoms. 450 00:33:07,027 --> 00:33:10,201 TYSON". He invented the weather map. 451 00:33:11,698 --> 00:33:17,171 And the symbols he devised for indicating prevailing winds are still in use today. 452 00:33:28,340 --> 00:33:32,265 Halley laid the groundwork for the science of population statistics. 453 00:33:32,427 --> 00:33:33,428 How? 454 00:33:33,595 --> 00:33:39,352 He compared the birth, marriage, death and population densities of London and Paris. 455 00:33:39,518 --> 00:33:42,863 He actually had to pace off the entire perimeter of Paris on foot... 456 00:33:43,021 --> 00:33:44,898 ...to learn its true dimensions. 457 00:33:45,065 --> 00:33:48,239 He came to the conclusion that since roughly half of all adults... 458 00:33:48,401 --> 00:33:51,701 ...fail to reproduce children, who themselves survive to reproduce... 459 00:33:52,405 --> 00:33:55,255 ...every married couple must have four 460 00:33:55,267 --> 00:33:58,128 children in order to maintain the population. 461 00:34:00,497 --> 00:34:04,377 And it was Edmond Halley who gave us the actual scale of the solar system. 462 00:34:04,543 --> 00:34:08,173 He figured out a clever way to find the distance from Earth to the sun. 463 00:34:08,338 --> 00:34:11,626 It involved precisely measuring the time it took 464 00:34:11,638 --> 00:34:14,937 for the planet Venus to cross the sun's disc. 465 00:34:17,305 --> 00:34:19,603 Twenty-seven years after Halley's death... 466 00:34:19,766 --> 00:34:22,690 ...Captain James Cook made his first voyage to Tahiti... 467 00:34:22,852 --> 00:34:25,651 ...for the express purpose of testing Halley's method... 468 00:34:25,814 --> 00:34:28,613 ...during a transit of Venus across the sun. 469 00:34:28,775 --> 00:34:30,994 Using a special filter to protect his vision... 470 00:34:31,152 --> 00:34:33,780 ...from being destroyed by looking directly at the sun... 471 00:34:33,947 --> 00:34:36,416 ...Cook and his men made it possible for us to know... 472 00:34:36,575 --> 00:34:40,921 ...that the sun is 93 million miles from Earth. 473 00:34:41,621 --> 00:34:44,471 And Halley was the first to realize that the 474 00:34:44,483 --> 00:34:47,344 so-called fixed stars were not fixed at all. 475 00:34:48,003 --> 00:34:49,175 How'd he do it? 476 00:34:49,337 --> 00:34:50,884 He pored over the observations... 477 00:34:51,047 --> 00:34:54,347 ...made by the ancient Greek astronomers of the brightest stars. 478 00:34:54,509 --> 00:34:56,261 And he compared their observations... 479 00:34:56,428 --> 00:35:01,184 ...with the ones he himself made of the same stars 1800 years later. 480 00:35:01,349 --> 00:35:03,852 Why hadn't anyone noticed this before? 481 00:35:04,019 --> 00:35:06,647 Halley figured out that it would only become apparent... 482 00:35:06,813 --> 00:35:10,033 ...if you waited long enough between observations. 483 00:35:10,191 --> 00:35:13,445 It's hard to perceive the motions of things that are far away. 484 00:35:13,612 --> 00:35:16,024 And the stars are so very far away that you 485 00:35:16,036 --> 00:35:18,459 would need to track them for many centuries... 486 00:35:18,617 --> 00:35:22,292 ...before you could detect that they moved at all. 487 00:35:23,913 --> 00:35:28,009 TYSON: Halley discovered the first clue to a magnificent reality: 488 00:35:28,168 --> 00:35:31,593 All the stars are in motion, streaming past each other... 489 00:35:31,755 --> 00:35:34,383 ...rising and falling like merry-go-round horses... 490 00:35:34,549 --> 00:35:39,350 ...in their Newtonian dance around the center of our galaxy. 491 00:35:40,347 --> 00:35:44,568 And, oh, yes, there was that thing about the comet. 492 00:35:49,189 --> 00:35:51,908 What were those strange and beautiful celestial visitors... 493 00:35:52,067 --> 00:35:54,741 ...that appeared without warning from time to time? 494 00:35:54,903 --> 00:35:58,077 Halley set out to solve this mystery as a detective would... 495 00:35:58,239 --> 00:36:00,833 ...by gathering all credible eyewitness testimony. 496 00:36:00,992 --> 00:36:04,747 The earliest precise observations of a comet that Halley could find... 497 00:36:04,913 --> 00:36:08,508 ...were made in Constantinople by Nicephorus Gregoras... 498 00:36:08,667 --> 00:36:12,888 ...a Byzantine astronomer and monk, in June 1337. 499 00:36:13,046 --> 00:36:16,846 Halley hunted down every astronomical observation of a comet... 500 00:36:17,008 --> 00:36:22,686 ...recorded in Europe between 1472 and 1698. 501 00:36:22,847 --> 00:36:26,943 And remember, there was no such thing as a search engine or a computer. 502 00:36:27,102 --> 00:36:30,606 All Halley had were his books and his mind. 503 00:36:30,772 --> 00:36:32,115 Now here comes the hard part: 504 00:36:32,273 --> 00:36:35,368 Halley had to take the observations made for each comet... 505 00:36:35,527 --> 00:36:38,952 ...and find the shape of its actual path through space. 506 00:36:39,114 --> 00:36:41,208 No one else but Newton had yet attempted... 507 00:36:41,366 --> 00:36:44,586 ...to apply his new set of laws to an astronomical question. 508 00:36:44,744 --> 00:36:48,089 In an arduous tour de force of mathematical brilliance... 509 00:36:48,248 --> 00:36:54,802 ...Halley discovered that comets were bound to the sun in long elliptical orbits. 510 00:36:58,883 --> 00:37:03,059 And he was the first to know that the comets seen in 1531 511 00:37:04,139 --> 00:37:08,986 ...1607, and 1682... 512 00:37:09,144 --> 00:37:10,771 ...were one and the same. 513 00:37:10,937 --> 00:37:14,157 A single comet that returned every 76 years. 514 00:37:14,315 --> 00:37:17,819 In a stunning example of true pattern recognition... 515 00:37:17,986 --> 00:37:22,116 ...he predicted it would be seen again more than 5O years in the future. 516 00:37:24,492 --> 00:37:27,587 For millennia, comets had been props for mystics... 517 00:37:27,746 --> 00:37:31,876 ...who considered them to be merely omens of human events. 518 00:37:32,041 --> 00:37:36,387 Halley shattered their monopoly, beating them at their own game. 519 00:37:36,546 --> 00:37:40,016 A game that no scientist had ever played before: 520 00:37:40,175 --> 00:37:42,269 prophecy . 521 00:37:42,427 --> 00:37:44,179 And he did not hedge his bet. 522 00:37:44,345 --> 00:37:48,020 Like Babe Ruth predicting where his next home run would land in the stands... 523 00:37:48,183 --> 00:37:53,280 ...Halley stated flatly that the comet would return at the end of 1758... 524 00:37:53,438 --> 00:37:58,490 ...from a particular part of the sky, following a specific path. 525 00:37:58,651 --> 00:38:01,154 There is hardly a prophecy attempted by the mystics... 526 00:38:01,321 --> 00:38:05,417 ...that ever even strives for comparable precision. 527 00:38:26,054 --> 00:38:28,182 That's Halley's Comet. 528 00:38:28,348 --> 00:38:31,477 Out here at the edge of the solar system, it doesn't look like much. 529 00:38:31,643 --> 00:38:34,863 Just a big hunk of ice and rock in space. 530 00:38:35,021 --> 00:38:39,618 That's because beyond the orbit of Neptune, nearly 5 billion kilometers from the sun... 531 00:38:39,776 --> 00:38:41,870 ...comets lead very quiet lives. 532 00:38:44,697 --> 00:38:46,825 As it reaches the far end of its orbit... 533 00:38:46,991 --> 00:38:50,586 ...it'll slow down till the sun allows it to go no farther. 534 00:38:50,745 --> 00:38:55,592 Then it'll begin its long fall back to the inner solar system. 535 00:38:55,959 --> 00:38:59,088 Halley's Comet is in free fall around the sun. 536 00:38:59,254 --> 00:39:00,801 Everything in our solar system... 537 00:39:00,964 --> 00:39:04,434 ...the Earth, the moon, the other planets, comets, asteroids... 538 00:39:04,592 --> 00:39:07,596 ...all of them are falling around the sun. 539 00:39:07,762 --> 00:39:12,518 Gravity pulls the planets towards the sun, but because of their orbital momentum... 540 00:39:12,684 --> 00:39:17,565 ...they keep moving around the sun, never falling into it. 541 00:39:21,192 --> 00:39:25,618 Robert Hooke had died years before, having ruined his health with some bad habits: 542 00:39:25,780 --> 00:39:29,830 daily doses of wormwood, opium, mercury. 543 00:39:29,993 --> 00:39:32,507 A few months later, Newton was elected to 544 00:39:32,519 --> 00:39:35,045 replace him as president of the Royal Society. 545 00:39:35,206 --> 00:39:40,713 It is said that a portrait of Hooke once hung on these walls. 546 00:39:40,879 --> 00:39:44,929 Halley lived on to accomplish many more astonishing feats. 547 00:39:45,091 --> 00:39:49,312 He worked right up to his death at age 85. 548 00:39:49,971 --> 00:39:53,646 His final act was to call for a glass of wine. 549 00:39:53,808 --> 00:39:58,109 He downed it with pleasure and breathed his last breath. 550 00:39:58,271 --> 00:39:59,648 [GLASS SHATTERS] 551 00:40:03,151 --> 00:40:06,997 TYSON: Some believe that it was on a night like this... 552 00:40:07,155 --> 00:40:11,831 ...that Isaac Newton finally took his revenge against Robert Hooke. 553 00:40:19,792 --> 00:40:20,839 Heh. 554 00:40:26,716 --> 00:40:29,344 TYSON". But Halley's prophecy was not forgotten. 555 00:40:29,510 --> 00:40:33,185 Fifty years later, as the time of the predicted return approached... 556 00:40:33,348 --> 00:40:37,819 ...the world's astronomers vied to be the first to catch sight of his comet. 557 00:40:37,977 --> 00:40:39,775 They weren't disappointed. 558 00:40:39,938 --> 00:40:43,693 It's been welcomed back every 76 years since. 559 00:40:44,692 --> 00:40:47,354 When Halley's Comet returns to our skies, 560 00:40:47,366 --> 00:40:50,040 sunlight will warm up the ice on its surface... 561 00:40:50,198 --> 00:40:56,422 ...once again setting loose the dust and gases trapped within. 562 00:40:57,956 --> 00:41:03,258 Halley's Comet most recently visited our neighborhood back in 1986. 563 00:41:03,419 --> 00:41:09,643 And if you're seeing this in 2061, then you'll know it's back. 564 00:41:11,052 --> 00:41:15,353 May you feel the wonder of all those who came before you... 565 00:41:15,515 --> 00:41:17,358 ...and none of the fear. 566 00:41:18,226 --> 00:41:20,820 Newton's laws made it possible for Edmond Halley... 567 00:41:20,979 --> 00:41:26,736 ...to see some 50 years into the future and predict the behavior of a single comet. 568 00:41:27,402 --> 00:41:30,531 Scientists have been using these laws ever since... 569 00:41:30,697 --> 00:41:35,419 ...opening the way to the moon, and even beyond our solar system. 570 00:41:35,576 --> 00:41:39,922 The baby in the basket is learning to walk... 571 00:41:44,919 --> 00:41:47,843 ...and to know the cosmos. 572 00:41:52,093 --> 00:41:55,188 Which brings me to one last prophecy. 573 00:41:55,346 --> 00:41:58,475 Using nothing more than Newton's laws of gravitation... 574 00:41:58,641 --> 00:42:03,147 ...we astronomers can confidently predict that several billion years from now... 575 00:42:03,312 --> 00:42:05,940 ...our home galaxy, the Milky Way... 576 00:42:06,107 --> 00:42:10,829 ...will merge with our neighboring galaxy Andromeda. 577 00:42:11,446 --> 00:42:15,952 Because the distances between the stars are so great compared to their sizes... 578 00:42:16,117 --> 00:42:20,463 ...few if any stars in either galaxy will actually collide. 579 00:42:20,621 --> 00:42:24,501 Any life on the worlds of that far-off future should be safe... 580 00:42:24,667 --> 00:42:29,798 ...but they would be treated to an amazing, billion-year-long light show... 581 00:42:31,090 --> 00:42:35,186 ...a dance of a half a trillion stars... 582 00:42:35,553 --> 00:42:38,978 ...to music first heard on one little world... 583 00:42:39,140 --> 00:42:43,236 ...by a man who had but one true friend.