1 00:00:21,554 --> 00:00:23,389 ¶ ¶ 2 00:00:50,616 --> 00:00:52,985 ¶ ¶ 3 00:01:13,573 --> 00:01:15,574 ¶ ¶ 4 00:01:24,350 --> 00:01:27,653 NEIL DEGRASSE TYSON: The age and size of the cosmos 5 00:01:27,687 --> 00:01:30,789 are written in light. 6 00:01:30,824 --> 00:01:35,661 The nature of beauty and the substance of the stars, 7 00:01:35,695 --> 00:01:39,064 the laws of space and time... 8 00:01:39,099 --> 00:01:42,067 they were there all along, 9 00:01:42,102 --> 00:01:44,103 but we never saw them... 10 00:01:44,137 --> 00:01:47,973 until we devised a more powerful way of seeing. 11 00:01:48,007 --> 00:01:51,677 The story of this awakening has many beginnings 12 00:01:51,711 --> 00:01:53,846 and no ending. 13 00:01:53,880 --> 00:01:57,082 Its heroes come from many times and places-- 14 00:01:57,117 --> 00:01:59,918 an ancient Chinese philosopher, 15 00:01:59,953 --> 00:02:03,622 a wizard who amazed the caliphs of 11th-century Iraq, 16 00:02:03,656 --> 00:02:08,527 a poor German orphan enslaved to a harsh master. 17 00:02:08,561 --> 00:02:10,996 Each one brought us a little closer 18 00:02:11,030 --> 00:02:15,234 to unlocking the secrets hidden in light. 19 00:02:17,871 --> 00:02:21,306 Most of their names are forever lost to us, 20 00:02:21,341 --> 00:02:25,844 but somewhere, long ago, someone glanced up 21 00:02:25,912 --> 00:02:30,249 to see light perform one of its magic tricks. 22 00:02:51,571 --> 00:02:52,571 Who knows? 23 00:02:52,605 --> 00:02:54,373 Maybe that quirk of light 24 00:02:54,407 --> 00:02:56,542 inspired the very first artist. 25 00:02:56,576 --> 00:02:57,609 (horse neighs) 26 00:03:08,788 --> 00:03:11,823 Where did all this come from? 27 00:03:11,858 --> 00:03:15,427 How did we evolve from small wandering bands 28 00:03:15,461 --> 00:03:17,596 of hunters and gatherers living beneath the stars 29 00:03:17,630 --> 00:03:21,400 to become the builders of a global civilization? 30 00:03:21,434 --> 00:03:24,870 How did we get from there to here? 31 00:03:24,904 --> 00:03:26,705 There's no one answer. 32 00:03:26,739 --> 00:03:29,408 Climate change, the domestication of fire, 33 00:03:29,442 --> 00:03:33,946 the invention of tools, language, agriculture 34 00:03:33,980 --> 00:03:37,249 all played a role. 35 00:03:37,283 --> 00:03:39,918 Maybe there was something else, too. 36 00:03:39,953 --> 00:03:43,071 In China, more than 2,000 years ago, 37 00:03:43,122 --> 00:03:46,291 a philosopher named Mo Tze is said to have observed 38 00:03:46,326 --> 00:03:48,694 that light could be made to paint a picture 39 00:03:48,728 --> 00:03:50,963 inside a locked treasure room. 40 00:03:50,997 --> 00:03:56,435 This was the description of the first camera... 41 00:03:56,469 --> 00:03:58,570 the camera obscura, 42 00:03:58,605 --> 00:04:00,973 the prototype of all image-forming cameras, 43 00:04:01,007 --> 00:04:04,276 including the one that's bringing you this picture. 44 00:04:04,310 --> 00:04:06,912 Taking advantage of this funny thing that light does 45 00:04:06,946 --> 00:04:11,917 resulted in what could be called the first movie. 46 00:04:11,951 --> 00:04:17,706 Mo Tze, master of light, worked against all forms of darkness. 47 00:04:17,757 --> 00:04:19,491 A military genius 48 00:04:19,525 --> 00:04:22,661 who only used his talents to prevent violence, 49 00:04:22,695 --> 00:04:24,663 he was legendary for traveling 50 00:04:24,697 --> 00:04:26,798 among the kingdoms of the warring states, 51 00:04:26,833 --> 00:04:28,567 employing ingenious strategies 52 00:04:28,601 --> 00:04:30,636 to talk kings out of going to war. 53 00:04:30,670 --> 00:04:34,239 He was one of the first to dream of universal love 54 00:04:34,274 --> 00:04:37,342 and an end to poverty and other forms of inequality; 55 00:04:37,377 --> 00:04:41,346 of government for the people... 56 00:04:41,348 --> 00:04:43,782 and to argue against blind obedience 57 00:04:43,816 --> 00:04:45,183 to ritual and authority. 58 00:04:45,251 --> 00:04:46,785 In his writings, you can find 59 00:04:46,852 --> 00:04:50,522 early stirrings of the scientific approach. 60 00:04:50,556 --> 00:04:53,492 By Mo Tze's time, the Chinese had already been recording 61 00:04:53,526 --> 00:04:56,862 their thoughts in books for at least a thousand years. 62 00:04:56,896 --> 00:04:59,831 Still, our knowledge of him is only fragmentary. 63 00:04:59,866 --> 00:05:02,301 It consists largely of the collection of essays 64 00:05:02,335 --> 00:05:04,002 attributed to him and his disciples. 65 00:05:04,037 --> 00:05:07,172 In one of them, entitled "Against Fate," 66 00:05:07,206 --> 00:05:10,309 a three-pronged test for every doctrine is proposed: 67 00:05:10,343 --> 00:05:12,844 Question its basis-- 68 00:05:12,879 --> 00:05:14,546 ask if it can be verified 69 00:05:14,580 --> 00:05:17,115 by the sights and senses of common people-- 70 00:05:17,150 --> 00:05:18,884 ask how it is to be applied 71 00:05:18,918 --> 00:05:21,253 and if it will benefit the greatest number. 72 00:05:23,156 --> 00:05:25,590 (door opens, people shouting) 73 00:05:25,692 --> 00:05:28,160 Mo Tze was extremely popular, 74 00:05:28,194 --> 00:05:30,495 but a few hundred years after his death, 75 00:05:30,530 --> 00:05:33,465 Qin Shi Huang, the first emperor, 76 00:05:33,499 --> 00:05:36,535 and unifier of China, took power. 77 00:05:36,569 --> 00:05:39,137 He took a continent and turned it into a nation 78 00:05:39,172 --> 00:05:42,507 that now bears his name: China. 79 00:05:42,608 --> 00:05:43,842 (blow strikes, man grunts) 80 00:05:45,611 --> 00:05:50,082 Most of us know Emperor Qin for the army of 7,000 81 00:05:50,116 --> 00:05:53,418 terra cotta warriors that guard his tomb. 82 00:05:55,288 --> 00:05:58,223 In Emperor Qin's drive 83 00:05:58,257 --> 00:06:00,859 to consolidate his far-flung empire, 84 00:06:00,893 --> 00:06:02,561 he took drastic measures 85 00:06:02,628 --> 00:06:05,063 to standardize everything within it. 86 00:06:05,098 --> 00:06:08,016 This included mandating a single coinage, 87 00:06:08,067 --> 00:06:10,602 making uniform all weights and measures, 88 00:06:10,636 --> 00:06:14,439 the widths of carts and roads, as well as the precise way 89 00:06:14,474 --> 00:06:16,675 the Chinese language was to be written, 90 00:06:16,709 --> 00:06:21,747 including what you were allowed to write and think. 91 00:06:21,781 --> 00:06:24,549 Emperor Qin's philosophy-- the only one permitted-- 92 00:06:24,584 --> 00:06:26,184 was called "legalism," 93 00:06:26,219 --> 00:06:28,787 which is just what it sounded like: 94 00:06:28,821 --> 00:06:32,224 do as the law says... or else. 95 00:06:32,241 --> 00:06:34,893 It's a philosophy that's not highly conducive 96 00:06:34,927 --> 00:06:36,928 to questioning authority. 97 00:06:39,232 --> 00:06:42,367 (man speaking Chinese) 98 00:06:42,402 --> 00:06:45,203 MAN: ...that all the books of the hundred schools of thought 99 00:06:45,238 --> 00:06:46,872 shall be be burned, 100 00:06:46,906 --> 00:06:50,308 that anyone who uses history to criticize the present 101 00:06:50,343 --> 00:06:52,611 shall have his family executed. 102 00:06:52,645 --> 00:06:54,613 (people gasping) 103 00:06:54,647 --> 00:06:56,748 DEGRASSE TYSON: The works of MoTze and Confucius 104 00:06:56,783 --> 00:06:58,984 and other philosophers were destroyed 105 00:06:59,018 --> 00:07:00,986 in the world's first book burning. 106 00:07:01,020 --> 00:07:03,572 Hundreds of scholars bravely resisted 107 00:07:03,623 --> 00:07:06,324 by trying to preserve the forbidden books. 108 00:07:06,326 --> 00:07:08,960 They were buried alive in the capitol. 109 00:07:10,696 --> 00:07:14,499 Science needs the light of free expression to flourish. 110 00:07:14,534 --> 00:07:17,903 It depends on the fearless questioning of authority, 111 00:07:17,937 --> 00:07:20,505 the open exchange of ideas. 112 00:07:20,540 --> 00:07:24,242 Sparks of curiosity in the writings of Mo Tze 113 00:07:24,277 --> 00:07:28,013 and his disciples were effectively stomped out. 114 00:07:28,047 --> 00:07:32,651 It would be another thousand years before the next movie. 115 00:07:34,554 --> 00:07:36,788 Luckily, our Ship of the Imagination 116 00:07:36,823 --> 00:07:40,826 can take us anywhere in space... and time. 117 00:07:48,534 --> 00:07:51,203 The ancient Chinese and Greeks observed 118 00:07:51,237 --> 00:07:52,871 that light could be made 119 00:07:52,905 --> 00:07:55,707 to do wonderful things-- but no one asked that question 120 00:07:55,741 --> 00:08:01,012 favored by small children and geniuses alike: Why? 121 00:08:01,047 --> 00:08:04,082 Until a thousand years ago... 122 00:08:09,188 --> 00:08:11,523 In the city of Basra, Iraq, 123 00:08:11,557 --> 00:08:13,458 there lived another master of light. 124 00:08:13,559 --> 00:08:18,897 Ibn al-Hazen had a passionate desire to understand nature. 125 00:08:18,931 --> 00:08:21,032 He questioned everything, 126 00:08:21,067 --> 00:08:25,003 especially those things that everyone else took for granted. 127 00:08:26,939 --> 00:08:30,141 "How do we see?" he asked. 128 00:08:30,159 --> 00:08:32,544 Some of the great authorities who came before him 129 00:08:32,578 --> 00:08:36,147 had taught that rays come out of our eyes and travel 130 00:08:36,182 --> 00:08:40,519 to the objects we see before returning to our eyes. 131 00:08:40,553 --> 00:08:44,422 But al-Hazen reasoned that the stars were too far distant 132 00:08:44,490 --> 00:08:47,025 for something in our eyes to travel all the way to them 133 00:08:47,059 --> 00:08:49,694 and back in the blink of an eye. 134 00:08:49,729 --> 00:08:53,365 Excellent reasoning, but al-Hazen didn't stop there. 135 00:08:53,399 --> 00:08:57,669 He searched for ways to compel nature to divulge her secrets. 136 00:08:57,703 --> 00:09:01,006 His culture was open to new ideas and questioning. 137 00:09:01,040 --> 00:09:03,508 It was the golden age of science 138 00:09:03,543 --> 00:09:05,744 in the Islamic world. 139 00:09:05,778 --> 00:09:09,214 One that stretched from Cordoba in Spain 140 00:09:09,248 --> 00:09:12,851 all the way to Samarkand in Central Asia. 141 00:09:12,885 --> 00:09:15,887 Christian and Jewish scholars were honored guests 142 00:09:15,922 --> 00:09:18,623 at the research institutes of Baghdad, Cairo, 143 00:09:18,658 --> 00:09:21,192 and other Islamic capitols. 144 00:09:21,227 --> 00:09:24,763 Instead of burning books, the caliphs sent emissaries 145 00:09:24,797 --> 00:09:27,732 around the world in search of books. 146 00:09:41,514 --> 00:09:45,917 The caliphs lavishly funded projects to translate, study, 147 00:09:45,952 --> 00:09:48,153 and preserve them for future generations. 148 00:09:48,187 --> 00:09:51,122 Much of the light of ancient Greek science would have been 149 00:09:51,157 --> 00:09:53,592 permanently extinguished without their efforts. 150 00:09:53,659 --> 00:09:56,428 The reawakening to science that took place in Europe, 151 00:09:56,462 --> 00:09:59,497 hundreds of years later, was kindled by a flame 152 00:09:59,532 --> 00:10:00,765 that had been long tended 153 00:10:00,800 --> 00:10:03,668 by Islamic scholars and scientists. 154 00:10:03,703 --> 00:10:07,238 The Arabs also imported ideas from India to the West, 155 00:10:07,256 --> 00:10:09,774 including the so-called Arabic numerals 156 00:10:09,875 --> 00:10:12,143 that we all use today, 157 00:10:12,178 --> 00:10:14,963 and the concept of zero... 158 00:10:17,650 --> 00:10:19,117 ...which comes in handy 159 00:10:19,151 --> 00:10:22,570 when you want to write "billions and billions." 160 00:10:22,622 --> 00:10:25,590 Arabic astronomy was so influential, 161 00:10:25,625 --> 00:10:27,592 that we still call most of the bright stars 162 00:10:27,693 --> 00:10:29,494 by their Arabic names. 163 00:10:29,528 --> 00:10:34,599 And the "al's" in algebra, algorithm, alchemy, and alcohol 164 00:10:34,634 --> 00:10:36,334 are just some of the traces left 165 00:10:36,369 --> 00:10:40,839 from the time when Arabic was the language of science. 166 00:10:42,742 --> 00:10:45,477 In the 11th century, Ibn al-Hazen set about trying 167 00:10:45,511 --> 00:10:49,547 to test his ideas about light and how we see. 168 00:10:49,582 --> 00:10:52,817 So we devised an experiment to determine how light moves. 169 00:10:52,852 --> 00:10:55,220 We erected a tent in full daylight 170 00:10:55,254 --> 00:10:58,356 and sealed it tightly so that only a single ray of light 171 00:10:58,391 --> 00:11:01,126 could pierce its inner darkness. 172 00:11:01,160 --> 00:11:03,461 With little more than his brains 173 00:11:03,496 --> 00:11:05,730 and a straight piece of wood-- a ruler-- 174 00:11:05,765 --> 00:11:07,632 al-Hazen had accomplished a great leap forward 175 00:11:07,667 --> 00:11:09,233 in the history of science. 176 00:11:09,235 --> 00:11:13,238 He discovered that light moves in straight lines. 177 00:11:18,411 --> 00:11:20,378 But he was just getting started. 178 00:11:20,413 --> 00:11:23,815 Al-Hazen figured out that the key to forming any image-- 179 00:11:23,849 --> 00:11:26,885 whether you're talking about an eye or camera obscura-- 180 00:11:26,919 --> 00:11:29,587 is a small opening to restrict the light that can enter 181 00:11:29,622 --> 00:11:31,489 an otherwise darkened chamber. 182 00:11:31,524 --> 00:11:34,392 That aperture excludes the chaos 183 00:11:34,394 --> 00:11:37,095 of extraneous light rays that surround us. 184 00:11:37,129 --> 00:11:38,763 The smaller the aperture, 185 00:11:38,798 --> 00:11:41,365 the fewer directions that light can come from. 186 00:11:41,367 --> 00:11:43,468 And that makes the image sharper. 187 00:11:43,569 --> 00:11:46,337 So instead of being blinded by the light, 188 00:11:46,372 --> 00:11:49,541 we can see everything it has to show us. 189 00:11:49,575 --> 00:11:52,861 Al-Hazen made his own camera obscura 190 00:11:52,928 --> 00:11:54,946 and dazzled the caliphs. 191 00:11:54,980 --> 00:11:58,049 A camera obscura works best in bright light. 192 00:11:58,084 --> 00:12:01,870 The stars of the night sky are way too dim for this. 193 00:12:01,921 --> 00:12:05,223 We somehow need a bigger opening to collect light, 194 00:12:05,257 --> 00:12:07,692 but we also need to maintain focus. 195 00:12:07,727 --> 00:12:10,361 A telescope collects light 196 00:12:10,396 --> 00:12:12,697 from any spot in its field of view 197 00:12:12,732 --> 00:12:15,700 across the entire lens or mirror, 198 00:12:15,735 --> 00:12:19,437 an opening much larger than the camera obscura hole. 199 00:12:19,472 --> 00:12:23,374 This is one of the first telescopes... 200 00:12:23,409 --> 00:12:27,479 the one that Galileo looked through in 1609. 201 00:12:27,513 --> 00:12:31,750 With it, he pulled aside the heavy curtain of night 202 00:12:31,784 --> 00:12:34,686 and began to discover the cosmos. 203 00:12:47,299 --> 00:12:49,300 The lens made it possible 204 00:12:49,335 --> 00:12:52,403 for a telescope to have a much larger light-collecting area 205 00:12:52,438 --> 00:12:54,739 than our eyes have. 206 00:12:54,774 --> 00:12:58,176 Big buckets catch more rain than small ones. 207 00:12:58,210 --> 00:13:01,112 Modern telescopes have larger collecting areas, 208 00:13:01,147 --> 00:13:02,814 highly sensitive detectors, 209 00:13:02,848 --> 00:13:05,750 and they track the same object for hours at a time 210 00:13:05,785 --> 00:13:09,120 to accumulate as much of its light as possible. 211 00:13:09,155 --> 00:13:11,923 Space-based telescopes such as the Hubble, 212 00:13:11,957 --> 00:13:13,792 have captured light from the most distant 213 00:13:13,826 --> 00:13:15,460 and ancient galaxies, 214 00:13:15,494 --> 00:13:18,663 giving us vastly clearer pictures of the cosmos. 215 00:13:20,299 --> 00:13:24,002 Al-Hazen discovered how images are formed by light, 216 00:13:24,036 --> 00:13:26,371 but that was far from his greatest achievement. 217 00:13:26,405 --> 00:13:29,107 Ibn al-Hazen was the first person ever 218 00:13:29,141 --> 00:13:31,810 to set down the rules of science. 219 00:13:31,844 --> 00:13:34,279 He created an error-correcting mechanism, 220 00:13:34,380 --> 00:13:36,781 a systematic and relentless way 221 00:13:36,882 --> 00:13:39,517 to sift out misconceptions in our thinking. 222 00:13:39,552 --> 00:13:44,522 Finding truth is difficult... 223 00:13:44,557 --> 00:13:47,525 and the road to it is rough. 224 00:13:47,560 --> 00:13:49,828 As seekers after truth, 225 00:13:49,862 --> 00:13:52,964 you will be wise to withhold judgment and not simply put 226 00:13:52,982 --> 00:13:55,867 your trust in the writings of the ancients. 227 00:13:55,901 --> 00:13:59,704 You must question and critically examine those writings 228 00:13:59,738 --> 00:14:02,240 from every side. 229 00:14:02,274 --> 00:14:05,510 You must submit only to argument and experiment 230 00:14:05,544 --> 00:14:08,913 and not to the sayings of any person. 231 00:14:08,948 --> 00:14:11,482 For every human being is vulnerable 232 00:14:11,517 --> 00:14:14,185 to all kinds of imperfection. 233 00:14:14,220 --> 00:14:16,654 As seekers after truth, 234 00:14:16,689 --> 00:14:19,023 we must also suspect and question 235 00:14:19,058 --> 00:14:22,660 our own ideas as we perform our investigations, 236 00:14:22,695 --> 00:14:27,599 to avoid falling into prejudice or careless thinking. 237 00:14:27,633 --> 00:14:32,871 Take this course, and truth will be revealed to you. 238 00:14:49,755 --> 00:14:52,924 DEGRASSE TYSON: This is the method of science. 239 00:14:52,958 --> 00:14:55,760 So powerful that it's carried our robotic emissaries 240 00:14:55,794 --> 00:14:59,230 to the edge of the solar system and beyond. 241 00:15:00,966 --> 00:15:03,251 It has doubled our lifespan, 242 00:15:03,302 --> 00:15:05,069 made the lost worlds of the past 243 00:15:05,104 --> 00:15:07,105 come alive. 244 00:15:08,507 --> 00:15:10,742 Science has enabled us to predict events 245 00:15:10,776 --> 00:15:13,244 in the distant future... 246 00:15:13,279 --> 00:15:16,748 and to communicate with each other at the speed of light, 247 00:15:16,782 --> 00:15:19,384 as I am with you, right at this moment. 248 00:15:19,418 --> 00:15:21,452 This way of thinking has given us powers 249 00:15:21,487 --> 00:15:25,123 that al-Hazen himself would have regarded as wizardry. 250 00:15:28,627 --> 00:15:32,997 But it was he who put us on this rough, endless road. 251 00:15:34,867 --> 00:15:37,735 And now it has taken us to a place 252 00:15:37,770 --> 00:15:42,473 where even light itself is enshrouded in darkness. 253 00:15:50,432 --> 00:15:52,567 Light has properties unlike anything else 254 00:15:52,601 --> 00:15:54,469 in the realm of human existence. 255 00:15:54,503 --> 00:15:56,638 Take the speed of light. 256 00:15:56,672 --> 00:15:58,773 The basic particle of light, the photon, 257 00:15:58,807 --> 00:16:01,476 is born traveling at the speed of light 258 00:16:01,510 --> 00:16:04,278 as it emerges from an atom or a molecule. 259 00:16:04,313 --> 00:16:06,447 A photon never knows any other speed, 260 00:16:06,482 --> 00:16:09,283 and we've not found another phenomenon that accelerates 261 00:16:09,318 --> 00:16:12,253 from zero to top speed instantaneously. 262 00:16:12,287 --> 00:16:14,489 Nothing else could move as fast. 263 00:16:14,523 --> 00:16:17,158 When we try to accelerate other particles closer and closer 264 00:16:17,192 --> 00:16:19,894 to the speed of light, they resist more and more, 265 00:16:19,928 --> 00:16:21,663 as though they're getting heavier and heavier. 266 00:16:21,697 --> 00:16:23,131 No experiment yet devised 267 00:16:23,165 --> 00:16:27,168 has ever made a particle move as fast as light. 268 00:16:27,202 --> 00:16:30,204 (musical notes play, confined to a single octave) 269 00:16:33,842 --> 00:16:36,477 What was that? 270 00:16:36,512 --> 00:16:38,680 You hear something? 271 00:16:38,714 --> 00:16:40,848 Where was I? Oh, yeah. 272 00:16:40,883 --> 00:16:44,952 I don't know anything else in life that behaves like light. 273 00:16:44,987 --> 00:16:48,423 I cannot reconcile its strange properties 274 00:16:48,457 --> 00:16:51,092 with everything else my senses tell me. 275 00:16:51,126 --> 00:16:54,095 Our urge to trust our senses overpowers 276 00:16:54,129 --> 00:16:56,197 what our measuring devices tell us about 277 00:16:56,231 --> 00:16:58,132 the actual nature of reality. 278 00:16:58,167 --> 00:17:00,334 Our senses work fine for life-size objects 279 00:17:00,369 --> 00:17:02,170 moving at mammal speeds, 280 00:17:02,204 --> 00:17:06,808 but are ill-adapted for the wonderland laws of lightspeed. 281 00:17:10,979 --> 00:17:14,348 We don't even know why there's a cosmic speed limit. 282 00:17:14,383 --> 00:17:17,819 Time stands still when you're traveling at the speed of light. 283 00:17:17,853 --> 00:17:20,321 What is light, anyway? 284 00:17:23,859 --> 00:17:27,361 Isaac Newton's enduring fascination with light 285 00:17:27,396 --> 00:17:29,564 began when he was a child.... 286 00:17:32,000 --> 00:17:34,435 ...in this very house. 287 00:17:39,508 --> 00:17:43,678 By the time he was in his 20s, Newton became the first person 288 00:17:43,712 --> 00:17:46,881 to decipher the mystery of the rainbow. 289 00:17:50,586 --> 00:17:53,888 Newton discovered that some light, or white light, 290 00:17:53,890 --> 00:17:56,891 is a mixture of all the colors of the rainbow. 291 00:17:59,428 --> 00:18:01,496 Major discovery. 292 00:18:01,530 --> 00:18:04,065 He named the displays of colors a "spectrum" 293 00:18:04,099 --> 00:18:08,352 from the Latin for "phantom" or "apparition." 294 00:18:18,480 --> 00:18:20,581 (knocking on door, door opens) 295 00:18:20,616 --> 00:18:22,583 Begging your pardon, Master Newton, 296 00:18:22,618 --> 00:18:25,319 the cook frets that your dinner will spoil, sir. 297 00:18:28,223 --> 00:18:30,391 DEGRASSE TYSON: No, Isaac, don't put the magnifying glass down! 298 00:18:30,425 --> 00:18:34,195 Something even more amazing is hidden in the light-- 299 00:18:34,229 --> 00:18:36,731 a code, a key to the cosmos. 300 00:18:43,505 --> 00:18:47,408 Isaac Newton didn't miss much, but that one was a beaut. 301 00:18:47,442 --> 00:18:50,545 He just walked right past the door to a hidden universe; 302 00:18:50,579 --> 00:18:54,615 a door that would not swing open again for another 150 years. 303 00:18:54,650 --> 00:18:56,951 It would fall on another scientist, 304 00:18:56,985 --> 00:18:58,653 working in the year 1800, 305 00:18:58,720 --> 00:19:00,655 to stumble on a piece of evidence 306 00:19:00,689 --> 00:19:03,691 for the unseen worlds that surround us. 307 00:19:07,262 --> 00:19:09,964 By night, William Herschel scanned the heavens 308 00:19:09,998 --> 00:19:12,466 with the largest telescope of his time. 309 00:19:12,501 --> 00:19:15,436 By day, Herschel performed experiments. 310 00:19:15,470 --> 00:19:18,105 From Newton's earlier work, it was known that sunlight 311 00:19:18,140 --> 00:19:20,508 is a blend of different colors. 312 00:19:20,542 --> 00:19:22,910 And everyone knew, just from being outside, 313 00:19:22,945 --> 00:19:25,146 that sunlight carries heat. 314 00:19:26,682 --> 00:19:28,683 William Herschel asked 315 00:19:28,685 --> 00:19:31,285 whether some colors of light carry more heat than others. 316 00:19:31,320 --> 00:19:35,423 The nature of scientific genius is to question 317 00:19:35,457 --> 00:19:38,259 what the rest of us take for granted... 318 00:19:38,293 --> 00:19:40,862 and then do the experiment. 319 00:19:42,898 --> 00:19:46,367 The thermometer that Herschel placed outside the spectrum 320 00:19:46,369 --> 00:19:48,369 was his control. 321 00:19:50,072 --> 00:19:51,973 The control in any experiment 322 00:19:52,007 --> 00:19:54,642 always lacks the factor being tested. 323 00:19:54,676 --> 00:19:56,777 That way, you know if what you're testing is 324 00:19:56,812 --> 00:19:58,913 really the thing responsible for the observation. 325 00:20:00,048 --> 00:20:01,349 In Herschel's experiment, 326 00:20:01,383 --> 00:20:02,984 the relationship between 327 00:20:03,018 --> 00:20:04,385 color and temperature was being tested, 328 00:20:04,419 --> 00:20:07,488 and so his control was a thermometer 329 00:20:07,522 --> 00:20:09,190 over the part of the white sheet 330 00:20:09,224 --> 00:20:12,526 that was not illuminated by sunlight at all. 331 00:20:12,561 --> 00:20:14,829 (musical notes play, confined to a single octave) 332 00:20:14,863 --> 00:20:16,397 There's that sound again. 333 00:20:16,431 --> 00:20:19,166 What is that? 334 00:20:24,907 --> 00:20:27,408 Okay, red light is warmer than blue light. 335 00:20:27,442 --> 00:20:32,513 Interesting discovery, but not exactly revolutionary. 336 00:20:54,036 --> 00:20:57,738 No, there's nothing wrong with your thermometer. 337 00:20:57,773 --> 00:21:01,125 You've just discovered a new kind of light. 338 00:21:09,985 --> 00:21:13,054 Herschel was the first to detect this unseen presence 339 00:21:13,088 --> 00:21:16,257 lurking just below the red end of the spectrum. 340 00:21:16,291 --> 00:21:19,193 That's why it came to be called "infrared." 341 00:21:19,227 --> 00:21:21,395 "Infra" is Latin for the word "below." 342 00:21:21,430 --> 00:21:22,997 It's invisible. 343 00:21:23,031 --> 00:21:25,399 Our eyes are not sensitive to this kind of light, 344 00:21:25,434 --> 00:21:28,302 but our skin is-- we feel it as heat. 345 00:21:28,337 --> 00:21:30,137 Now, that's a really big discovery. 346 00:21:30,172 --> 00:21:32,573 But far greater secrets were still hiding 347 00:21:32,607 --> 00:21:35,076 deep inside the light. 348 00:21:40,766 --> 00:21:42,800 DEGRASSE TYSON: At about the same time that William Herschel 349 00:21:42,834 --> 00:21:45,736 was discovering infrared light in his parlor in England, 350 00:21:45,771 --> 00:21:48,239 a young boy named Joseph Fraunhofer 351 00:21:48,273 --> 00:21:50,741 was trapped in hopeless drudgery. 352 00:21:50,776 --> 00:21:53,711 He stood over a cauldron of toxic chemicals 353 00:21:53,745 --> 00:21:56,113 and endlessly stirred. 354 00:21:58,016 --> 00:22:00,818 Joseph had been orphaned at the age of 11 355 00:22:00,885 --> 00:22:04,655 and given to a harsh master named Weichselberger, 356 00:22:04,690 --> 00:22:07,625 the royal mirror-maker. 357 00:22:07,627 --> 00:22:09,927 He prevented Joseph from going to school. 358 00:22:09,961 --> 00:22:13,164 Instead, Joseph labored in 359 00:22:13,198 --> 00:22:15,132 the glass-making workshop by day, 360 00:22:15,167 --> 00:22:17,635 and tended to the master's household chores by night. 361 00:22:17,669 --> 00:22:19,103 (thunder crashes) 362 00:22:23,141 --> 00:22:24,642 WEICHSELBERGER: Hurry up, stupid! 363 00:22:24,676 --> 00:22:27,595 And remember, no reading. 364 00:22:27,646 --> 00:22:28,913 (door thuds shut) 365 00:22:31,983 --> 00:22:34,819 DEGRASSE TYSON: Until Joseph got his big break. 366 00:22:34,853 --> 00:22:37,321 Weichselberger's house collapsed. 367 00:22:37,356 --> 00:22:39,857 (rumbling) 368 00:22:45,664 --> 00:22:47,665 (men murmuring) 369 00:22:51,970 --> 00:22:54,071 (Weichselberger groaning weakly) 370 00:22:56,675 --> 00:22:58,542 Maximilian, the future king of Bavaria, 371 00:22:58,577 --> 00:23:00,478 hurried to the scene of the calamity 372 00:23:00,512 --> 00:23:02,046 to see if he could help. 373 00:23:02,080 --> 00:23:04,515 Maximilian was known for 374 00:23:04,549 --> 00:23:06,150 taking an interest in his subjects, 375 00:23:06,184 --> 00:23:08,386 which was highly unusual for its time. 376 00:23:16,595 --> 00:23:18,596 (townsfolk murmuring) 377 00:23:22,267 --> 00:23:25,403 In attracting the concern of the future king of Bavaria, 378 00:23:25,437 --> 00:23:27,037 young Joseph Fraunhofer 379 00:23:27,072 --> 00:23:29,874 found an aperture into a different universe. 380 00:23:29,908 --> 00:23:32,343 And not just for himself. 381 00:23:35,480 --> 00:23:37,214 Prince Maximilian gave Joseph money 382 00:23:37,249 --> 00:23:39,049 and asked his privy councilor 383 00:23:39,084 --> 00:23:40,518 to provide further help to the boy, 384 00:23:40,552 --> 00:23:42,920 should it be needed. 385 00:23:47,793 --> 00:23:50,494 Weichselberger continued to exploit him 386 00:23:50,529 --> 00:23:52,830 and prevent him from attending school. 387 00:23:52,864 --> 00:23:54,899 But the prince's councilor intervened, 388 00:23:54,933 --> 00:23:58,436 offering Joseph a position at the Optical Institute. 389 00:23:58,470 --> 00:24:03,607 This small gesture of kindness really paid off. 390 00:24:15,954 --> 00:24:18,789 By the time he was 27, 391 00:24:18,824 --> 00:24:21,058 Joseph Fraunhofer was the world's leading designer 392 00:24:21,092 --> 00:24:23,093 of high-quality lenses, 393 00:24:23,128 --> 00:24:25,796 telescopes and other optical instruments. 394 00:24:25,831 --> 00:24:29,700 His firm was housed here, in the old Benediktbeuren Abbey. 395 00:24:29,734 --> 00:24:31,902 In the early 19th century, 396 00:24:31,937 --> 00:24:35,239 this was top-secret, ultra-high technology. 397 00:24:38,276 --> 00:24:40,478 The Benedictine monks of earlier times 398 00:24:40,512 --> 00:24:42,480 had taken a vow of secrecy. 399 00:24:42,514 --> 00:24:44,482 This local tradition, 400 00:24:44,516 --> 00:24:45,983 and the ability to restrict access 401 00:24:46,017 --> 00:24:47,551 to Fraunhofer's laboratory, 402 00:24:47,586 --> 00:24:49,553 allowed him to maintain control 403 00:24:49,588 --> 00:24:52,656 of trade and state secrets. 404 00:24:57,762 --> 00:25:00,064 Fraunhofer was experimenting with prisms 405 00:25:00,098 --> 00:25:03,501 to find the best types of glass for precision lenses. 406 00:25:03,535 --> 00:25:06,237 How, he wondered, could he get a better look 407 00:25:06,271 --> 00:25:08,272 at the spectrum that a prism produced? 408 00:25:11,443 --> 00:25:15,246 Friedrich, bring me the theodolite, please. 409 00:25:15,280 --> 00:25:18,182 Okay, while Fraunhofer sets up his theodolite-- 410 00:25:18,216 --> 00:25:20,017 it's a kind of telescope-- 411 00:25:20,051 --> 00:25:23,354 I want to show you something in another part of the abbey. 412 00:25:27,993 --> 00:25:31,729 Sound waves are so beautiful to hear. 413 00:25:33,565 --> 00:25:38,269 Imagine how beautiful they'd be to see. 414 00:25:38,303 --> 00:25:41,505 You ever wondered why organ pipes have different lengths? 415 00:25:43,742 --> 00:25:44,975 I press a key... 416 00:25:45,010 --> 00:25:47,444 (high note plays) 417 00:25:47,479 --> 00:25:48,879 ...it sends compressed air 418 00:25:48,914 --> 00:25:50,147 into a particular pipe, 419 00:25:50,181 --> 00:25:51,982 producing sound waves. 420 00:25:52,017 --> 00:25:54,718 If we could slow the sound waves down a few hundred times, 421 00:25:54,753 --> 00:25:56,887 they would look like this. 422 00:25:56,922 --> 00:25:59,323 (notes playing) 423 00:26:00,592 --> 00:26:02,226 The length of the pipe 424 00:26:02,260 --> 00:26:03,694 determines the length of the sound wave 425 00:26:03,728 --> 00:26:05,195 that can fit inside it. 426 00:26:05,230 --> 00:26:07,298 A short pipe gives you a short sound wave. 427 00:26:07,332 --> 00:26:09,300 (high note plays) 428 00:26:09,334 --> 00:26:12,069 Short sounds waves have high pitch, or frequency. 429 00:26:17,576 --> 00:26:20,244 Let's stop the waves for a better look. 430 00:26:22,213 --> 00:26:24,582 (low note plays) 431 00:26:24,616 --> 00:26:26,550 The distance between adjacent waves 432 00:26:26,585 --> 00:26:28,352 is called the wavelength. 433 00:26:28,386 --> 00:26:30,888 A long pipe gives you a long sound wave 434 00:26:30,922 --> 00:26:33,290 with a low pitch, or low frequency. 435 00:26:35,026 --> 00:26:38,028 (playing classical melody) 436 00:26:38,046 --> 00:26:39,430 (clears throat) 437 00:26:39,464 --> 00:26:41,899 (stops playing) 438 00:26:47,906 --> 00:26:50,240 (playing "Fortuna" from "Carmina Burana") 439 00:27:10,295 --> 00:27:12,630 ¶ ¶ 440 00:27:17,335 --> 00:27:18,902 (stops playing) 441 00:27:24,843 --> 00:27:27,745 The medieval manuscript of this music, "Carmina Burana," 442 00:27:27,779 --> 00:27:30,948 was discovered in this very abbey. 443 00:27:34,152 --> 00:27:36,587 Sound waves can't travel through a vacuum. 444 00:27:36,621 --> 00:27:38,489 They need matter to ride on, 445 00:27:38,523 --> 00:27:41,992 like molecules of air, or water, or rock. 446 00:27:42,027 --> 00:27:44,128 But light waves fly solo. 447 00:27:44,162 --> 00:27:46,330 They can move through empty space. 448 00:27:46,364 --> 00:27:47,965 And fast-- 449 00:27:47,999 --> 00:27:51,101 a million times faster than sound waves in air. 450 00:27:51,136 --> 00:27:53,103 And the wavelengths of the light we see 451 00:27:53,138 --> 00:27:55,639 are so much shorter than sound waves. 452 00:27:55,674 --> 00:27:58,509 About 50,000 light waves 453 00:27:58,543 --> 00:28:00,978 would fit right in here. 454 00:28:02,147 --> 00:28:03,681 Oh, yeah. 455 00:28:03,715 --> 00:28:05,149 Fraunhofer. 456 00:28:11,790 --> 00:28:13,123 Just in time. 457 00:28:13,158 --> 00:28:14,792 We didn't miss it. 458 00:28:14,826 --> 00:28:16,994 Just as the wavelength of sound 459 00:28:17,028 --> 00:28:18,996 determines the pitch that we hear, 460 00:28:19,030 --> 00:28:20,497 the wavelength of light 461 00:28:20,565 --> 00:28:22,966 determines the color that we see. 462 00:28:23,001 --> 00:28:25,436 But how does a prism spread out the colors 463 00:28:25,470 --> 00:28:27,971 concealed in a beam of sunlight? 464 00:28:28,006 --> 00:28:31,942 When light travels through air or space, 465 00:28:31,976 --> 00:28:34,344 all its colors move at the same speed. 466 00:28:36,381 --> 00:28:39,149 But when it hits glass at an angle, 467 00:28:39,184 --> 00:28:41,585 the light slows down and changes direction. 468 00:28:43,154 --> 00:28:45,122 Inside the prism, 469 00:28:45,156 --> 00:28:47,157 each color moves at a different speed. 470 00:28:51,496 --> 00:28:53,297 In glass, violet light, 471 00:28:53,331 --> 00:28:55,499 which is carried by the shortest waves we see, 472 00:28:55,533 --> 00:28:57,534 slows down more than red light, 473 00:28:57,569 --> 00:29:00,003 which has the longest waves. 474 00:29:01,840 --> 00:29:04,241 These changes in speed 475 00:29:04,275 --> 00:29:06,810 pry the colors apart, 476 00:29:06,845 --> 00:29:08,645 sending their waves off 477 00:29:08,680 --> 00:29:11,081 in slightly different directions. 478 00:29:12,283 --> 00:29:14,284 That's how a prism works. 479 00:29:16,421 --> 00:29:18,689 If I seem unduly emotional about this, 480 00:29:18,723 --> 00:29:21,508 it's because Joseph Fraunhofer is about to do 481 00:29:21,559 --> 00:29:25,062 what Isaac Newton could've done, but didn't. 482 00:29:25,064 --> 00:29:27,164 And it'll have a powerful effect 483 00:29:27,198 --> 00:29:29,032 on the course of my own life. 484 00:29:52,056 --> 00:29:54,091 You are witnessing the marriage 485 00:29:54,093 --> 00:29:55,726 of physics and astronomy, 486 00:29:55,760 --> 00:29:59,563 the birth of my own field of science: 487 00:29:59,664 --> 00:30:02,099 astrophysics. 488 00:30:04,102 --> 00:30:05,869 Written in the light, 489 00:30:05,904 --> 00:30:09,306 in those vertical black lines... 490 00:30:10,742 --> 00:30:13,710 ...is secret code. 491 00:30:13,745 --> 00:30:16,547 Fraunhofer looked at them, and wondered... 492 00:30:16,581 --> 00:30:18,582 Why? 493 00:30:20,485 --> 00:30:23,821 DEGRASSE TYSON: A code that comes to us 494 00:30:23,855 --> 00:30:26,290 from an alien universe. 495 00:30:29,878 --> 00:30:31,879 ¶ ¶ 496 00:30:35,483 --> 00:30:37,885 DEGRASSE TYSON: What is the message 497 00:30:37,919 --> 00:30:40,420 written in these dark, vertical lines? 498 00:30:45,493 --> 00:30:47,561 It took a hundred years of thinking, 499 00:30:47,595 --> 00:30:50,898 questioning, searching to decipher it. 500 00:31:10,451 --> 00:31:12,586 Lovely, isn't it? 501 00:31:12,620 --> 00:31:14,154 Why? 502 00:31:14,188 --> 00:31:17,658 There are many layers to the fine structure of beauty... 503 00:31:17,692 --> 00:31:20,827 the chemistry of the Earth and its atmosphere... 504 00:31:20,862 --> 00:31:23,797 the evolution of life... 505 00:31:23,831 --> 00:31:27,401 Many distinct threads. 506 00:31:27,435 --> 00:31:30,504 Let's just examine one, at the surface: 507 00:31:30,538 --> 00:31:32,940 the colors of nature that dazzle us. 508 00:31:32,974 --> 00:31:36,076 What's really happening? 509 00:31:36,110 --> 00:31:37,978 How does the red, the blue... 510 00:31:38,012 --> 00:31:40,981 the astonishing palette of nature's colors... 511 00:31:44,986 --> 00:31:47,621 ...how do they happen? 512 00:31:50,291 --> 00:31:52,459 Light waves of different lengths from the Sun 513 00:31:52,493 --> 00:31:53,894 strike the Earth. 514 00:31:55,296 --> 00:31:57,331 The petals of these particular flowers 515 00:31:57,365 --> 00:31:58,965 absorb all the low-energy, 516 00:31:58,967 --> 00:32:01,201 long red wavelengths of light. 517 00:32:01,235 --> 00:32:02,936 But the petals reflect 518 00:32:02,971 --> 00:32:06,273 the shorter, high-energy blue wavelengths. 519 00:32:06,307 --> 00:32:09,042 That interaction between starlight and petal-- 520 00:32:09,077 --> 00:32:11,044 or water, or Van Gogh-- 521 00:32:11,079 --> 00:32:12,646 is what makes blue. 522 00:32:12,680 --> 00:32:14,815 The longest waves, 523 00:32:14,849 --> 00:32:16,650 the ones we see as red, 524 00:32:16,684 --> 00:32:19,252 have the lowest energy. 525 00:32:22,190 --> 00:32:24,524 Color is the way our eyes perceive 526 00:32:24,559 --> 00:32:26,426 how energetic light waves are. 527 00:32:28,262 --> 00:32:29,963 A sunset... 528 00:32:29,981 --> 00:32:32,132 a flag... 529 00:32:32,166 --> 00:32:34,568 the eyes of your beloved... 530 00:32:34,602 --> 00:32:36,336 that shiny new car. 531 00:32:36,371 --> 00:32:38,338 The feelings they inspire 532 00:32:38,373 --> 00:32:40,173 happen when something inside you 533 00:32:40,208 --> 00:32:42,676 is triggered by a particular variation 534 00:32:42,710 --> 00:32:46,179 in the frequency and energy of light waves. 535 00:32:47,949 --> 00:32:49,082 And the secret message? 536 00:32:49,117 --> 00:32:50,817 Those black vertical lines 537 00:32:50,852 --> 00:32:52,853 in Fraunhofer's spectrum? 538 00:32:52,887 --> 00:32:55,021 What makes them? 539 00:32:55,023 --> 00:32:57,190 They occur when the light waves 540 00:32:57,225 --> 00:32:59,993 of those particular colors are being absorbed. 541 00:33:00,028 --> 00:33:02,562 It happens on another level of reality, 542 00:33:02,630 --> 00:33:05,599 far smaller than the world we're used to operating in. 543 00:33:05,633 --> 00:33:08,201 To get there, we'll need to become 544 00:33:08,236 --> 00:33:10,971 ten billion times smaller than we are. 545 00:33:13,741 --> 00:33:16,109 We could pick any one of these atoms. 546 00:33:16,144 --> 00:33:19,212 But let's go for the hydrogen atom. 547 00:33:19,247 --> 00:33:21,715 The hydrogen atom is the most plentiful kind 548 00:33:21,749 --> 00:33:24,117 of atom in the cosmos. 549 00:33:24,152 --> 00:33:26,553 And the simplest. 550 00:33:34,062 --> 00:33:37,230 It has only one electron. 551 00:33:37,265 --> 00:33:39,766 And only one proton. 552 00:33:39,801 --> 00:33:41,868 We've entered the quantum realm. 553 00:33:41,903 --> 00:33:43,704 It doesn't correspond 554 00:33:43,738 --> 00:33:46,473 to ordinary human experience. 555 00:33:46,507 --> 00:33:49,710 Common sense is no help here at all. 556 00:33:49,744 --> 00:33:52,746 Take the hydrogen atom's electron, for example. 557 00:33:54,682 --> 00:33:56,917 In an atom, an electron 558 00:33:56,951 --> 00:33:58,652 doesn't exist between orbitals. 559 00:33:58,686 --> 00:34:00,454 It disappears from one orbital 560 00:34:00,488 --> 00:34:03,123 and reappears in another. 561 00:34:03,157 --> 00:34:04,958 It's as if you took an elevator from the second floor 562 00:34:04,992 --> 00:34:08,261 to the fourth floor, but ceased to exist in between. 563 00:34:08,296 --> 00:34:09,996 And another thing. 564 00:34:10,031 --> 00:34:12,966 Quantum elevators only stop at certain floors. 565 00:34:13,000 --> 00:34:16,403 The sizes of the electron orbits are strictly limited, 566 00:34:16,437 --> 00:34:19,272 and different for the atoms of every element. 567 00:34:20,808 --> 00:34:23,143 That's why the elements are different. 568 00:34:23,177 --> 00:34:24,511 The chemistry of anything is determined 569 00:34:24,545 --> 00:34:26,113 by its electron orbits. 570 00:34:26,147 --> 00:34:29,015 The force that holds an electron in orbit 571 00:34:29,050 --> 00:34:30,851 has nothing to do with gravity. 572 00:34:30,885 --> 00:34:34,421 It's a force of electrical attraction. 573 00:34:34,455 --> 00:34:36,757 The electron dances a wavy ring 574 00:34:36,791 --> 00:34:39,025 around the central nucleus of a hydrogen atom. 575 00:34:39,060 --> 00:34:41,828 And makes quantum leaps from orbit to orbit. 576 00:34:41,863 --> 00:34:43,130 Up or down. 577 00:34:43,164 --> 00:34:44,531 The larger the orbit, 578 00:34:44,565 --> 00:34:46,600 the greater the energy of an electron. 579 00:34:46,634 --> 00:34:49,002 An electron has 580 00:34:49,036 --> 00:34:51,171 to get energy to leap to a larger orbit. 581 00:34:51,205 --> 00:34:54,007 And it has to lose energy to jump back down. 582 00:34:54,041 --> 00:34:57,344 Every upward leap is caused by... 583 00:34:57,378 --> 00:35:00,781 an atom absorbing a light wave. 584 00:35:00,815 --> 00:35:04,618 But we have no idea what causes the downward leaps. 585 00:35:04,652 --> 00:35:08,221 What we do know that such leaps always produce a light wave 586 00:35:08,256 --> 00:35:10,891 whose color matches the energy difference 587 00:35:10,958 --> 00:35:12,692 between the orbitals. 588 00:35:17,598 --> 00:35:22,002 The Sun's surface radiates light waves of all colors. 589 00:35:22,036 --> 00:35:23,837 If you look at sunlight through a prism, 590 00:35:23,871 --> 00:35:25,872 you'll see its spectrum. 591 00:35:28,509 --> 00:35:31,344 When you magnify the spectrum with a telescope, 592 00:35:31,379 --> 00:35:33,246 as Joseph Fraunhofer did, 593 00:35:33,281 --> 00:35:34,848 you raise the curtain 594 00:35:34,882 --> 00:35:38,084 on the electron dance within the atom. 595 00:35:38,119 --> 00:35:40,320 When the energy of the electron flags, 596 00:35:40,354 --> 00:35:42,022 and it drops to a lower orbital, 597 00:35:42,056 --> 00:35:44,424 the light wave it emits scatters. 598 00:35:44,458 --> 00:35:46,860 Most of it doesn't reach us. 599 00:35:46,894 --> 00:35:48,428 That leaves a dark gap 600 00:35:48,462 --> 00:35:51,298 or black vertical line in the spectrum. 601 00:35:51,399 --> 00:35:53,934 These dark lines are the shadows 602 00:35:53,968 --> 00:35:55,569 cast by hydrogen atoms 603 00:35:55,603 --> 00:35:57,537 in the atmosphere of the Sun. 604 00:35:57,572 --> 00:36:00,306 Sodium atoms cast different shadows. 605 00:36:00,308 --> 00:36:03,376 Their electrons dance to a different tune. 606 00:36:03,411 --> 00:36:05,278 A grain of table salt is composed 607 00:36:05,313 --> 00:36:07,113 of sodium and chlorine atoms. 608 00:36:07,148 --> 00:36:09,583 Ten million billion of them 609 00:36:09,617 --> 00:36:11,585 doing their crazy dances 610 00:36:11,619 --> 00:36:14,454 in a single grain of salt. 611 00:36:14,488 --> 00:36:17,390 And a single iron atom with 26 electrons 612 00:36:17,425 --> 00:36:19,759 is like a great big production number 613 00:36:19,794 --> 00:36:23,096 in a Broadway musical. 614 00:36:25,532 --> 00:36:29,402 When you look at a star with a spectroscope, 615 00:36:29,437 --> 00:36:31,872 you see the dark lines from all the elements 616 00:36:31,906 --> 00:36:33,540 in its atmosphere. 617 00:36:33,574 --> 00:36:35,442 Show me the spectrum of anything, 618 00:36:35,476 --> 00:36:38,245 whether here on Earth or from a distant star, 619 00:36:38,279 --> 00:36:41,314 and I'll tell you what it's made of. 620 00:36:41,349 --> 00:36:44,951 Fraunhofer's lines are the atomic signatures 621 00:36:44,986 --> 00:36:49,022 of the elements writ large across the cosmos. 622 00:36:49,024 --> 00:36:51,057 As with every other major revelation 623 00:36:51,092 --> 00:36:53,593 in the history of science, it opened the way 624 00:36:53,628 --> 00:36:56,596 to newer and deeper mysteries. 625 00:36:56,631 --> 00:36:59,599 And to the revelation that there were 626 00:36:59,634 --> 00:37:02,669 many more secrets hiding in the light. 627 00:37:15,967 --> 00:37:18,885 When Joseph Fraunhofer combined a prism with a telescope 628 00:37:18,887 --> 00:37:21,171 and turned it toward the skies, 629 00:37:21,173 --> 00:37:24,674 he brought the stars much closer to us. 630 00:37:35,653 --> 00:37:38,388 When he was only 39, 631 00:37:38,390 --> 00:37:40,557 he contracted a fatal illness. 632 00:37:40,559 --> 00:37:43,226 Perhaps as a result of his early and long-term exposure 633 00:37:43,228 --> 00:37:46,162 to the toxic chemicals of glassmaking. 634 00:37:46,164 --> 00:37:50,166 You never know where the next genius will come from. 635 00:37:54,038 --> 00:37:58,608 How many of them do we leave in the rubble? 636 00:37:58,610 --> 00:38:01,878 The prince and his kingdom were immeasurably enriched 637 00:38:01,880 --> 00:38:05,248 by that act of kindness to a poor orphan. 638 00:38:05,250 --> 00:38:07,684 Fraunhofer's discoveries transformed Bavaria 639 00:38:07,686 --> 00:38:11,955 from a rural backwater to a technological powerhouse. 640 00:38:13,791 --> 00:38:16,159 As he lay dying, the government was desperate 641 00:38:16,161 --> 00:38:19,129 to preserve every shred of his precious knowledge 642 00:38:19,131 --> 00:38:21,431 about the high technology of optical glass. 643 00:38:24,468 --> 00:38:26,403 But it could only be divulged to a person 644 00:38:26,405 --> 00:38:28,605 with top security clearance-- 645 00:38:28,607 --> 00:38:30,373 the director of the mint. 646 00:38:30,375 --> 00:38:34,244 (no voice) 647 00:38:47,458 --> 00:38:50,060 The government kept Fraunhofer's technology 648 00:38:50,062 --> 00:38:51,961 for making perfect optical glass 649 00:38:51,963 --> 00:38:55,231 a State secret for another hundred years. 650 00:38:55,233 --> 00:38:57,233 This would prove to be a major obstacle 651 00:38:57,268 --> 00:38:59,736 for someone we'll meet later in our journey. 652 00:38:59,770 --> 00:39:02,305 But Fraunhofer would allow no such secrecy 653 00:39:02,339 --> 00:39:04,908 where his pure scientific research was concerned. 654 00:39:04,942 --> 00:39:08,545 He knew that science requires openness to flourish; 655 00:39:08,579 --> 00:39:12,615 that our understanding of nature belongs to the world. 656 00:39:12,650 --> 00:39:15,552 As soon as Fraunhofer discovered the spectral lines, 657 00:39:15,586 --> 00:39:18,121 he published everything he knew about them. 658 00:39:18,155 --> 00:39:20,957 And the reverberations of his momentous discovery 659 00:39:21,024 --> 00:39:23,760 echo still. 660 00:39:26,931 --> 00:39:30,900 His spectral lines revealed that the visible cosmos 661 00:39:30,935 --> 00:39:34,204 is all made of the same elements. 662 00:39:37,041 --> 00:39:39,509 The planets... 663 00:39:47,651 --> 00:39:50,120 The stars... 664 00:39:54,492 --> 00:39:56,559 The galaxies... 665 00:40:00,865 --> 00:40:03,867 We, ourselves, and all of life... 666 00:40:10,541 --> 00:40:14,077 The same star stuff. 667 00:40:19,517 --> 00:40:21,184 He made it possible for us to know 668 00:40:21,218 --> 00:40:23,686 what's in the atmosphere of other worlds. 669 00:40:26,157 --> 00:40:29,793 And in galaxies millions of light-years away. 670 00:40:29,827 --> 00:40:31,828 Spectral lines revealed not only the composition 671 00:40:31,862 --> 00:40:34,330 of far-off objects, but also their motion 672 00:40:34,365 --> 00:40:36,533 towards or away from us. 673 00:40:36,567 --> 00:40:39,636 Using them, we discovered that our universe is expanding. 674 00:40:39,670 --> 00:40:43,239 But perhaps the greatest revelation of spectroscopy 675 00:40:43,274 --> 00:40:46,075 is the discovery of the thing it cannot see. 676 00:40:52,082 --> 00:40:54,250 A hidden universe of dark matter 677 00:40:54,285 --> 00:40:57,520 six times more massive than the familiar cosmos. 678 00:40:57,555 --> 00:40:59,722 It's made of some mysterious substance 679 00:40:59,757 --> 00:41:04,327 that does not emit, reflect or absorb any kind of light. 680 00:41:04,361 --> 00:41:06,813 We only know it's there because of its gravity, 681 00:41:06,864 --> 00:41:08,932 which pulls on all the galaxies 682 00:41:08,966 --> 00:41:11,701 and speeds up the visible stars within them. 683 00:41:15,706 --> 00:41:19,175 There are many more kinds of light than our eyes can see. 684 00:41:19,210 --> 00:41:22,612 Confining our perception of nature to visible light 685 00:41:22,646 --> 00:41:24,948 is like listening to music 686 00:41:24,982 --> 00:41:26,549 in only one octave. 687 00:41:26,584 --> 00:41:29,085 (musical notes play, confined to one octave) 688 00:41:29,119 --> 00:41:31,120 There are so many more. 689 00:41:31,155 --> 00:41:33,089 They differ only in wavelength, 690 00:41:33,123 --> 00:41:35,225 but over a huge range. 691 00:41:35,259 --> 00:41:37,827 For instance, infrared light... 692 00:41:39,430 --> 00:41:43,132 (musical notes play in a higher octave) 693 00:41:43,167 --> 00:41:46,302 ...the kind that William Herschel discovered 694 00:41:46,337 --> 00:41:48,104 Or X-ray light. 695 00:41:48,138 --> 00:41:50,473 (musical notes play in a still-higher octave) 696 00:41:53,177 --> 00:41:55,245 Or radio light. 697 00:41:55,279 --> 00:41:57,614 (musical notes play in a lower octave) 698 00:41:59,984 --> 00:42:01,818 Or in gamma-ray light. 699 00:42:01,852 --> 00:42:04,254 (music notes play in the highest octave humans can hear) 700 00:42:07,625 --> 00:42:10,894 These are not just different ways of seeing the same thing. 701 00:42:10,928 --> 00:42:12,495 These other kinds of light 702 00:42:12,529 --> 00:42:16,132 reveal different objects and phenomena in the cosmos. 703 00:42:16,166 --> 00:42:19,335 In gamma-ray light, for example, we can see mysterious explosions 704 00:42:19,370 --> 00:42:21,104 in distant galaxies 705 00:42:21,138 --> 00:42:23,439 that we would otherwise miss. 706 00:42:26,377 --> 00:42:29,245 And in microwave light, we can see all the way back 707 00:42:29,280 --> 00:42:31,681 to the birth of the universe. 708 00:42:34,218 --> 00:42:37,520 We have only just opened our eyes. 709 00:42:39,556 --> 00:42:42,492 (range of octaves play in George Gershwin's "Rhapsody in Blue") 710 00:42:50,301 --> 00:42:42,492 Captioned by Media Access Group at WGBH access.wgbh.org