1 00:01:30,503 --> 00:01:32,003 "Hiding In The Light" 2 00:01:36,418 --> 00:01:38,820 The age and size of the cosmos 3 00:01:38,854 --> 00:01:41,956 are written in light. 4 00:01:41,991 --> 00:01:46,828 The nature of beauty and the substance of the stars, 5 00:01:46,862 --> 00:01:50,231 the laws of space and time... 6 00:01:50,266 --> 00:01:53,234 they were there all along, 7 00:01:53,269 --> 00:01:55,270 but we never saw them... 8 00:01:55,304 --> 00:01:59,140 until we devised a more powerful way of seeing. 9 00:01:59,175 --> 00:02:02,844 The story of this awakening has many beginnings 10 00:02:02,878 --> 00:02:05,013 and no ending. 11 00:02:05,047 --> 00:02:08,249 Its heroes come from many times and places-- 12 00:02:08,284 --> 00:02:11,086 an Ancient Chinese philosopher, 13 00:02:11,120 --> 00:02:14,789 a wizard who amazed the caliphs of 11th-century Iraq, 14 00:02:14,824 --> 00:02:19,694 a poor German orphan enslaved to a harsh master. 15 00:02:19,728 --> 00:02:22,163 Each one brought us a little closer 16 00:02:22,198 --> 00:02:26,401 to unlocking the secrets hidden in light. 17 00:02:29,038 --> 00:02:32,474 Most of their names are forever lost to us, 18 00:02:32,508 --> 00:02:37,011 but somewhere, long ago, someone glanced up 19 00:02:37,046 --> 00:02:41,416 to see light perform one of its magic tricks. 20 00:03:02,738 --> 00:03:03,738 Who knows? 21 00:03:03,773 --> 00:03:05,540 Maybe that quirk of light 22 00:03:05,574 --> 00:03:07,709 inspired the very first artist. 23 00:03:19,955 --> 00:03:22,991 Where did all this come from? 24 00:03:23,025 --> 00:03:26,594 How did we evolve from small wandering bands 25 00:03:26,629 --> 00:03:28,763 of hunters and gatherers living beneath the stars 26 00:03:28,798 --> 00:03:32,567 to become the builders of a global civilization? 27 00:03:32,601 --> 00:03:36,037 How did we get from there to here? 28 00:03:36,071 --> 00:03:37,872 There's no one answer. 29 00:03:37,907 --> 00:03:40,575 Climate change, the domestication of fire, 30 00:03:40,609 --> 00:03:45,113 the invention of tools, language, agriculture 31 00:03:45,147 --> 00:03:48,416 all played a role. 32 00:03:48,451 --> 00:03:51,085 Maybe there was something else, too. 33 00:03:51,120 --> 00:03:54,255 In China, more than 2,000 years ago, 34 00:03:54,290 --> 00:03:57,459 a philosopher named Mo Tze is said to have observed 35 00:03:57,493 --> 00:03:59,861 that light could be made to paint a picture 36 00:03:59,895 --> 00:04:02,130 inside a locked treasure room. 37 00:04:02,164 --> 00:04:07,602 This was the description of the first camera... 38 00:04:07,636 --> 00:04:09,737 the camera obscura, 39 00:04:09,772 --> 00:04:12,140 the prototype of all image-forming cameras, 40 00:04:12,174 --> 00:04:15,443 including the one that's bringing you this picture. 41 00:04:15,478 --> 00:04:18,079 Taking advantage of this funny thing that light does 42 00:04:18,114 --> 00:04:23,084 resulted in what could be called the first movie. 43 00:04:23,119 --> 00:04:28,890 Mo Tze, master of light, worked against all forms of darkness. 44 00:04:28,924 --> 00:04:30,658 A military genius 45 00:04:30,693 --> 00:04:33,828 who only used his talents to prevent violence, 46 00:04:33,863 --> 00:04:35,830 he was legendary for traveling 47 00:04:35,865 --> 00:04:37,966 among the kingdoms of the warring states, 48 00:04:38,000 --> 00:04:39,734 employing ingenious strategies 49 00:04:39,769 --> 00:04:41,803 to talk kings out of going to war. 50 00:04:41,837 --> 00:04:45,406 He was one of the first to dream of universal love 51 00:04:45,441 --> 00:04:48,510 and an end to poverty and other forms of inequality; 52 00:04:48,544 --> 00:04:52,480 of government for the people... 53 00:04:52,515 --> 00:04:54,949 and to argue against blind obedience 54 00:04:54,984 --> 00:04:56,351 to ritual and authority. 55 00:04:56,385 --> 00:04:57,952 In his writings, you can find 56 00:04:57,987 --> 00:05:01,689 early stirrings of the scientific approach. 57 00:05:01,724 --> 00:05:04,659 By Mo Tze's time, the Chinese had already been recording 58 00:05:04,693 --> 00:05:08,029 their thoughts in books for at least a thousand years. 59 00:05:08,063 --> 00:05:10,999 Still, our knowledge of him is only fragmentary. 60 00:05:11,033 --> 00:05:13,468 It consists largely of the collection of essays 61 00:05:13,502 --> 00:05:15,170 attributed to him and his disciples. 62 00:05:15,204 --> 00:05:18,339 In one of them, entitled "Against Fate," 63 00:05:18,374 --> 00:05:21,476 a three-pronged test for every doctrine is proposed. 64 00:05:21,510 --> 00:05:24,012 Question its basis-- 65 00:05:24,046 --> 00:05:25,713 ask if it can be verified 66 00:05:25,748 --> 00:05:28,283 by the sights and senses of common people-- 67 00:05:28,317 --> 00:05:30,051 ask how it is to be applied 68 00:05:30,085 --> 00:05:32,420 and if it will benefit the greatest number. 69 00:05:36,859 --> 00:05:39,327 Mo Tze was extremely popular, 70 00:05:39,361 --> 00:05:41,663 but a few hundred years after his death, 71 00:05:41,697 --> 00:05:44,632 Qin Shi Huang, the first emperor, 72 00:05:44,667 --> 00:05:47,702 and unifier of China, took power. 73 00:05:47,736 --> 00:05:50,305 He took a continent and turned it into a nation 74 00:05:50,339 --> 00:05:53,741 that now bears his name... China. 75 00:05:56,779 --> 00:06:01,249 Most of us know Emperor Qin for the army of 7,000 76 00:06:01,283 --> 00:06:04,586 terra cotta warriors that guard his tomb. 77 00:06:06,455 --> 00:06:09,390 In Emperor Qin's drive 78 00:06:09,425 --> 00:06:12,026 to consolidate his far-flung empire, 79 00:06:12,061 --> 00:06:13,728 he took drastic measures 80 00:06:13,763 --> 00:06:16,231 to standardize everything within it. 81 00:06:16,265 --> 00:06:19,200 This included mandating a single coinage, 82 00:06:19,235 --> 00:06:21,770 making uniform all weights and measures, 83 00:06:21,804 --> 00:06:25,607 the widths of carts and roads, as well as the precise way 84 00:06:25,641 --> 00:06:27,842 the Chinese language was to be written, 85 00:06:27,877 --> 00:06:32,914 including what you were allowed to write and think. 86 00:06:32,948 --> 00:06:35,717 Emperor Qin's philosophy-- the only one permitted-- 87 00:06:35,751 --> 00:06:37,352 was called "legalism," 88 00:06:37,386 --> 00:06:39,954 which is just what it sounded like, 89 00:06:39,989 --> 00:06:43,391 do as the law says... or else. 90 00:06:43,826 --> 00:06:46,460 It's a philosophy that's not highly conducive 91 00:06:46,495 --> 00:06:48,496 to questioning authority. 92 00:06:53,569 --> 00:06:56,371 ...that all the books of the hundred schools of thought 93 00:06:56,405 --> 00:06:58,039 shall be be burned, 94 00:06:58,073 --> 00:07:01,476 that anyone who uses history to criticize the present 95 00:07:01,510 --> 00:07:03,778 shall have his family executed. 96 00:07:05,815 --> 00:07:07,916 The works of MoTze and Confucius 97 00:07:07,950 --> 00:07:10,151 and other philosophers were destroyed 98 00:07:10,186 --> 00:07:12,153 in the world's first book burning. 99 00:07:12,188 --> 00:07:14,756 Hundreds of scholars bravely resisted 100 00:07:14,790 --> 00:07:17,492 by trying to preserve the forbidden books. 101 00:07:17,526 --> 00:07:20,128 They were buried alive in the capitol. 102 00:07:21,864 --> 00:07:25,667 Science needs the light of free expression to flourish. 103 00:07:25,701 --> 00:07:29,070 It depends on the fearless questioning of authority, 104 00:07:29,105 --> 00:07:31,673 the open exchange of ideas. 105 00:07:31,707 --> 00:07:35,410 Sparks of curiosity in the writings of Mo Tze 106 00:07:35,444 --> 00:07:39,180 and his disciples were effectively stomped out. 107 00:07:39,215 --> 00:07:43,818 It would be another thousand years before the next movie. 108 00:07:45,721 --> 00:07:47,956 Luckily, our Ship of the Imagination 109 00:07:47,990 --> 00:07:51,993 can take us anywhere in space... and time. 110 00:08:02,339 --> 00:08:05,007 The ancient Chinese and Greeks observed 111 00:08:05,042 --> 00:08:06,676 that light could be made 112 00:08:06,710 --> 00:08:09,512 to do wonderful things-- but no one asked that question 113 00:08:09,546 --> 00:08:14,817 favored by small children and geniuses alike. Why? 114 00:08:14,852 --> 00:08:17,887 Until a thousand years ago... 115 00:08:22,993 --> 00:08:25,328 In the city of Basra, Iraq, 116 00:08:25,362 --> 00:08:27,330 there lived another master of light. 117 00:08:27,364 --> 00:08:32,702 Ibn al-Hazen had a passionate desire to understand nature. 118 00:08:32,736 --> 00:08:34,837 He questioned everything, 119 00:08:34,872 --> 00:08:38,808 especially those things that everyone else took for granted. 120 00:08:40,744 --> 00:08:43,946 "How do we see?" he asked. 121 00:08:43,981 --> 00:08:46,349 Some of the great authorities who came before him 122 00:08:46,383 --> 00:08:49,952 had taught that rays come out of our eyes and travel 123 00:08:49,987 --> 00:08:54,323 to the objects we see before returning to our eyes. 124 00:08:54,358 --> 00:08:58,227 But al-Hazen reasoned that the stars were too far distant 125 00:08:58,262 --> 00:09:00,830 for something in our eyes to travel all the way to them 126 00:09:00,864 --> 00:09:03,499 and back in the blink of an eye. 127 00:09:03,534 --> 00:09:07,170 Excellent reasoning, but al-Hazen didn't stop there. 128 00:09:07,204 --> 00:09:11,474 He searched for ways to compel nature to divulge her secrets. 129 00:09:11,508 --> 00:09:14,810 His culture was open to new ideas and questioning. 130 00:09:14,845 --> 00:09:17,313 It was the golden age of science 131 00:09:17,347 --> 00:09:19,549 in the Islamic world. 132 00:09:19,583 --> 00:09:23,019 One that stretched from Cordoba in Spain 133 00:09:23,053 --> 00:09:26,656 all the way to Samarkand in Central Asia. 134 00:09:26,690 --> 00:09:29,692 Christian and Jewish scholars were honored guests 135 00:09:29,726 --> 00:09:32,428 at the research institutes of Baghdad, Cairo, 136 00:09:32,462 --> 00:09:34,997 and other Islamic capitols. 137 00:09:35,032 --> 00:09:38,568 Instead of burning books, the caliphs sent emissaries 138 00:09:38,602 --> 00:09:41,537 around the world in search of books. 139 00:09:55,319 --> 00:09:59,722 The caliphs lavishly funded projects to translate, study, 140 00:09:59,756 --> 00:10:01,958 and preserve them for future generations. 141 00:10:01,992 --> 00:10:04,927 Much of the light of Ancient Greek science would have been 142 00:10:04,962 --> 00:10:07,396 permanently extinguished without their efforts. 143 00:10:07,431 --> 00:10:10,233 The reawakening to science that took place in Europe, 144 00:10:10,267 --> 00:10:13,302 hundreds of years later, was kindled by a flame 145 00:10:13,337 --> 00:10:14,570 that had been long tended 146 00:10:14,605 --> 00:10:17,473 by Islamic scholars and scientists. 147 00:10:17,508 --> 00:10:21,043 The Arabs also imported ideas from India to the West, 148 00:10:21,078 --> 00:10:23,646 including the so-called Arabic numerals 149 00:10:23,680 --> 00:10:25,948 that we all use today, 150 00:10:25,983 --> 00:10:28,784 and the concept of zero... 151 00:10:31,455 --> 00:10:32,922 which comes in handy 152 00:10:32,956 --> 00:10:36,392 when you want to write "billions and billions." 153 00:10:36,426 --> 00:10:39,395 Arabic astronomy was so influential, 154 00:10:39,429 --> 00:10:41,464 that we still call most of the bright stars 155 00:10:41,498 --> 00:10:43,299 by their Arabic names. 156 00:10:43,333 --> 00:10:48,404 And the "al's" in algebra, algorithm, alchemy, and alcohol 157 00:10:48,438 --> 00:10:50,139 are just some of the traces left 158 00:10:50,174 --> 00:10:54,644 from the time when Arabic was the language of science. 159 00:10:56,547 --> 00:10:59,282 In the 11th century, Ibn al-Hazen set about trying 160 00:10:59,316 --> 00:11:03,352 to test his ideas about light and how we see. 161 00:11:03,387 --> 00:11:06,622 So we devised an experiment to determine how light moves. 162 00:11:06,657 --> 00:11:09,025 We erected a tent in full daylight 163 00:11:09,059 --> 00:11:12,161 and sealed it tightly so that only a single ray of light 164 00:11:12,196 --> 00:11:14,931 could pierce its inner darkness. 165 00:11:14,965 --> 00:11:17,266 With little more than his brains 166 00:11:17,301 --> 00:11:19,535 and a straight piece of wood-- a ruler-- 167 00:11:19,570 --> 00:11:21,437 al-Hazen had accomplished a great leap forward 168 00:11:21,471 --> 00:11:23,005 in the history of science. 169 00:11:23,040 --> 00:11:27,043 He discovered that light moves in straight lines. 170 00:11:32,216 --> 00:11:34,183 But he was just getting started. 171 00:11:34,218 --> 00:11:37,620 Al-Hazen figured out that the key to forming any image-- 172 00:11:37,654 --> 00:11:40,690 whether you're talking about an eye or camera obscura-- 173 00:11:40,724 --> 00:11:43,392 is a small opening to restrict the light that can enter 174 00:11:43,427 --> 00:11:45,294 an otherwise darkened chamber. 175 00:11:45,329 --> 00:11:48,197 That aperture excludes the chaos 176 00:11:48,232 --> 00:11:50,900 of extraneous light rays that surround us. 177 00:11:50,934 --> 00:11:52,568 The smaller the aperture, 178 00:11:52,603 --> 00:11:55,138 the fewer directions that light can come from. 179 00:11:55,172 --> 00:11:57,340 And that makes the image sharper. 180 00:11:57,374 --> 00:12:00,142 So instead of being blinded by the light, 181 00:12:00,177 --> 00:12:03,346 we can see everything it has to show us. 182 00:12:03,380 --> 00:12:06,682 Al-Hazen made his own camera obscura 183 00:12:06,717 --> 00:12:08,751 and dazzled the caliphs. 184 00:12:08,785 --> 00:12:11,854 A camera obscura works best in bright light. 185 00:12:11,889 --> 00:12:15,691 The stars of the night sky are way too dim for this. 186 00:12:15,726 --> 00:12:19,028 We somehow need a bigger opening to collect light, 187 00:12:19,062 --> 00:12:21,497 but we also need to maintain focus. 188 00:12:21,532 --> 00:12:24,167 A telescope collects light 189 00:12:24,201 --> 00:12:26,502 from any spot in its field of view 190 00:12:26,537 --> 00:12:29,505 across the entire lens or mirror, 191 00:12:29,540 --> 00:12:33,242 an opening much larger than the camera obscura hole. 192 00:12:33,277 --> 00:12:37,180 This is one of the first telescopes... 193 00:12:37,214 --> 00:12:41,284 the one that Galileo looked through in 1609. 194 00:12:41,318 --> 00:12:45,555 With it, he pulled aside the heavy curtain of night 195 00:12:45,589 --> 00:12:48,491 and began to discover the cosmos. 196 00:13:01,104 --> 00:13:03,105 The lens made it possible 197 00:13:03,140 --> 00:13:06,209 for a telescope to have a much larger light-collecting area 198 00:13:06,243 --> 00:13:08,544 than our eyes have. 199 00:13:08,579 --> 00:13:11,981 Big buckets catch more rain than small ones. 200 00:13:12,015 --> 00:13:14,917 Modern telescopes have larger collecting areas, 201 00:13:14,952 --> 00:13:16,619 highly sensitive detectors, 202 00:13:16,653 --> 00:13:19,555 and they track the same object for hours at a time 203 00:13:19,590 --> 00:13:22,925 to accumulate as much of its light as possible. 204 00:13:22,960 --> 00:13:25,728 Space-based telescopes such as the Hubble, 205 00:13:25,762 --> 00:13:27,597 have captured light from the most distant 206 00:13:27,631 --> 00:13:29,265 and ancient galaxies, 207 00:13:29,299 --> 00:13:32,468 giving us vastly clearer pictures of the cosmos. 208 00:13:34,104 --> 00:13:37,807 Al-Hazen discovered how images are formed by light, 209 00:13:37,841 --> 00:13:40,176 but that was far from his greatest achievement. 210 00:13:40,210 --> 00:13:42,912 Ibn al-Hazen was the first person ever 211 00:13:42,946 --> 00:13:45,615 to set down the rules of science. 212 00:13:45,649 --> 00:13:48,150 He created an error-correcting mechanism, 213 00:13:48,185 --> 00:13:50,653 a systematic and relentless way 214 00:13:50,687 --> 00:13:53,322 to sift out misconceptions in our thinking. 215 00:13:53,357 --> 00:13:58,327 Finding truth is difficult... 216 00:13:58,362 --> 00:14:01,330 and the road to it is rough. 217 00:14:01,365 --> 00:14:03,633 As seekers after truth, 218 00:14:03,667 --> 00:14:06,769 you will be wise to withhold judgment and not simply put 219 00:14:06,803 --> 00:14:09,672 your trust in the writings of the ancients. 220 00:14:09,706 --> 00:14:13,509 You must question and critically examine those writings 221 00:14:13,544 --> 00:14:16,045 from every side. 222 00:14:16,079 --> 00:14:19,315 You must submit only to argument and experiment 223 00:14:19,349 --> 00:14:22,718 and not to the sayings of any person. 224 00:14:22,753 --> 00:14:25,288 For every human being is vulnerable 225 00:14:25,322 --> 00:14:27,990 to all kinds of imperfection. 226 00:14:28,025 --> 00:14:30,459 As seekers after truth, 227 00:14:30,494 --> 00:14:32,828 we must also suspect and question 228 00:14:32,863 --> 00:14:36,465 our own ideas as we perform our investigations, 229 00:14:36,500 --> 00:14:41,404 to avoid falling into prejudice or careless thinking. 230 00:14:41,438 --> 00:14:46,676 Take this course, and truth will be revealed to you. 231 00:15:03,560 --> 00:15:06,729 This is the method of science. 232 00:15:06,763 --> 00:15:09,565 So powerful that it's carried our robotic emissaries 233 00:15:09,600 --> 00:15:13,035 to the edge of the solar system and beyond. 234 00:15:14,771 --> 00:15:17,073 It has doubled our lifespan, 235 00:15:17,107 --> 00:15:18,874 made the lost worlds of the past 236 00:15:18,909 --> 00:15:20,910 come alive. 237 00:15:22,312 --> 00:15:24,547 Science has enabled us to predict events 238 00:15:24,581 --> 00:15:27,049 in the distant future... 239 00:15:27,084 --> 00:15:30,553 and to communicate with each other at the speed of light, 240 00:15:30,587 --> 00:15:33,189 as I am with you, right at this moment. 241 00:15:33,223 --> 00:15:35,258 This way of thinking has given us powers 242 00:15:35,292 --> 00:15:38,928 that al-Hazen himself would have regarded as wizardry. 243 00:15:42,432 --> 00:15:46,802 But it was he who put us on this rough, endless road. 244 00:15:48,672 --> 00:15:51,540 And now it has taken us to a place 245 00:15:51,575 --> 00:15:56,279 where even light itself is enshrouded in darkness. 246 00:16:06,708 --> 00:16:08,843 Light has properties unlike anything else 247 00:16:08,877 --> 00:16:10,745 in the realm of human existence. 248 00:16:10,779 --> 00:16:12,914 Take the speed of light. 249 00:16:12,948 --> 00:16:15,049 The basic particle of light, the photon, 250 00:16:15,083 --> 00:16:17,752 is born traveling at the speed of light 251 00:16:17,786 --> 00:16:20,555 as it emerges from an atom or a molecule. 252 00:16:20,589 --> 00:16:22,723 A photon never knows any other speed, 253 00:16:22,758 --> 00:16:25,560 and we've not found another phenomenon that accelerates 254 00:16:25,594 --> 00:16:28,529 from zero to top speed instantaneously. 255 00:16:28,564 --> 00:16:30,765 Nothing else could move as fast. 256 00:16:30,799 --> 00:16:33,434 When we try to accelerate other particles closer and closer 257 00:16:33,468 --> 00:16:36,170 to the speed of light, they resist more and more, 258 00:16:36,205 --> 00:16:37,939 as though they're getting heavier and heavier. 259 00:16:37,973 --> 00:16:39,407 No experiment yet devised 260 00:16:39,441 --> 00:16:43,444 has ever made a particle move as fast as light. 261 00:16:50,118 --> 00:16:52,753 What was that? 262 00:16:52,788 --> 00:16:54,956 You hear something? 263 00:16:54,990 --> 00:16:57,124 Where was I? Oh, yeah. 264 00:16:57,159 --> 00:17:01,229 I don't know anything else in life that behaves like light. 265 00:17:01,263 --> 00:17:04,699 I cannot reconcile its strange properties 266 00:17:04,733 --> 00:17:07,368 with everything else my senses tell me. 267 00:17:07,402 --> 00:17:10,371 Our urge to trust our senses overpowers 268 00:17:10,405 --> 00:17:12,473 what our measuring devices tell us about 269 00:17:12,508 --> 00:17:14,408 the actual nature of reality. 270 00:17:14,443 --> 00:17:16,611 Our senses work fine for life-size objects 271 00:17:16,645 --> 00:17:18,446 moving at mammal speeds, 272 00:17:18,480 --> 00:17:23,084 but are ill-adapted for the wonderland laws of lightspeed. 273 00:17:27,256 --> 00:17:30,625 We don't even know why there's a cosmic speed limit. 274 00:17:30,659 --> 00:17:34,095 Time stands still when you're traveling at the speed of light. 275 00:17:34,129 --> 00:17:36,597 What is light, anyway? 276 00:17:40,135 --> 00:17:43,638 Isaac Newton's enduring fascination with light 277 00:17:43,672 --> 00:17:45,840 began when he was a child... 278 00:17:48,277 --> 00:17:50,711 in this very house. 279 00:17:55,784 --> 00:17:59,954 By the time he was in his 20s, Newton became the first person 280 00:17:59,988 --> 00:18:03,157 to decipher the mystery of the rainbow. 281 00:18:06,862 --> 00:18:10,164 Newton discovered that some light, or white light, 282 00:18:10,199 --> 00:18:13,167 is a mixture of all the colors of the rainbow. 283 00:18:15,704 --> 00:18:17,772 Major discovery. 284 00:18:17,806 --> 00:18:20,341 He named the displays of colors a "spectrum" 285 00:18:20,375 --> 00:18:24,645 from the Latin for "phantom" or "apparition." 286 00:18:36,892 --> 00:18:38,860 Begging your pardon, Master Newton, 287 00:18:38,894 --> 00:18:41,596 the cook frets that your dinner will spoil, sir. 288 00:18:44,500 --> 00:18:46,667 No, Isaac, don't put the magnifying glass down! 289 00:18:46,702 --> 00:18:50,471 Something even more amazing is hidden in the light-- 290 00:18:50,506 --> 00:18:53,007 a code, a key to the cosmos. 291 00:18:59,781 --> 00:19:03,684 Isaac Newton didn't miss much, but that one was a beaut. 292 00:19:03,719 --> 00:19:06,821 He just walked right past the door to a hidden universe; 293 00:19:06,855 --> 00:19:10,892 a door that would not swing open again for another 150 years. 294 00:19:10,926 --> 00:19:13,227 It would fall on another scientist, 295 00:19:13,262 --> 00:19:14,929 working in the year 1800, 296 00:19:14,963 --> 00:19:16,931 to stumble on a piece of evidence 297 00:19:16,965 --> 00:19:19,967 for the unseen worlds that surround us. 298 00:19:23,539 --> 00:19:25,972 By night, William Herschel scanned the heavens 299 00:19:26,006 --> 00:19:28,475 with the largest telescope of his time. 300 00:19:28,509 --> 00:19:31,445 By day, Herschel performed experiments. 301 00:19:31,479 --> 00:19:34,114 From Newton's earlier work, it was known that sunlight 302 00:19:34,148 --> 00:19:36,516 is a blend of different colors. 303 00:19:36,551 --> 00:19:38,918 And everyone knew, just from being outside, 304 00:19:38,953 --> 00:19:41,153 that sunlight carries heat. 305 00:19:42,689 --> 00:19:44,690 William Herschel asked 306 00:19:44,724 --> 00:19:47,293 whether some colors of light carry more heat than others. 307 00:19:47,327 --> 00:19:51,430 The nature of scientific genius is to question 308 00:19:51,465 --> 00:19:54,266 what the rest of us take for granted... 309 00:19:54,301 --> 00:19:56,867 and then do the experiment. 310 00:19:58,904 --> 00:20:02,340 The thermometer that Herschel placed outside the spectrum 311 00:20:02,374 --> 00:20:04,375 was his control. 312 00:20:06,078 --> 00:20:07,979 The control in any experiment 313 00:20:08,013 --> 00:20:10,648 always lacks the factor being tested. 314 00:20:10,682 --> 00:20:12,782 That way, you know if what you're testing is 315 00:20:12,817 --> 00:20:14,918 really the thing responsible for the observation. 316 00:20:16,053 --> 00:20:17,354 In Herschel's experiment, 317 00:20:17,388 --> 00:20:18,989 the relationship between 318 00:20:19,023 --> 00:20:20,390 color and temperature was being tested, 319 00:20:20,425 --> 00:20:23,494 and so his control was a thermometer 320 00:20:23,528 --> 00:20:25,195 over the part of the white sheet 321 00:20:25,230 --> 00:20:28,531 that was not illuminated by sunlight at all. 322 00:20:30,867 --> 00:20:32,401 There's that sound again. 323 00:20:32,436 --> 00:20:35,171 What is that? 324 00:20:40,910 --> 00:20:43,412 Okay, red light is warmer than blue light. 325 00:20:43,447 --> 00:20:48,517 Interesting discovery, but not exactly revolutionary. 326 00:21:10,038 --> 00:21:13,740 No, there's nothing wrong with your thermometer. 327 00:21:13,775 --> 00:21:17,143 You've just discovered a new kind of light. 328 00:21:25,986 --> 00:21:29,055 Herschel was the first to detect this unseen presence 329 00:21:29,089 --> 00:21:32,291 lurking just below the red end of the spectrum. 330 00:21:32,325 --> 00:21:35,227 That's why it came to be called "infrared." 331 00:21:35,261 --> 00:21:37,429 "Infra" is Latin for the word "below." 332 00:21:37,463 --> 00:21:39,030 It's invisible. 333 00:21:39,065 --> 00:21:41,433 Our eyes are not sensitive to this kind of light, 334 00:21:41,467 --> 00:21:44,336 but our skin is-- we feel it as heat. 335 00:21:44,370 --> 00:21:46,171 Now, that's a really big discovery. 336 00:21:46,206 --> 00:21:48,606 But far greater secrets were still hiding 337 00:21:48,640 --> 00:21:51,108 deep inside the light. 338 00:21:59,062 --> 00:22:01,096 At about the same time that William Herschel 339 00:22:01,130 --> 00:22:04,031 was discovering infrared light in his parlor in England, 340 00:22:04,066 --> 00:22:06,534 a young boy named Joseph Fraunhofer 341 00:22:06,569 --> 00:22:09,036 was trapped in hopeless drudgery. 342 00:22:09,071 --> 00:22:12,006 He stood over a cauldron of toxic chemicals 343 00:22:12,040 --> 00:22:14,409 and endlessly stirred. 344 00:22:16,311 --> 00:22:19,113 Joseph had been orphaned at the age of 11 345 00:22:19,147 --> 00:22:22,949 and given to a harsh master named Weichselberger, 346 00:22:22,984 --> 00:22:25,919 the royal mirror-maker. 347 00:22:25,953 --> 00:22:28,221 He prevented Joseph from going to school. 348 00:22:28,256 --> 00:22:31,458 Instead, Joseph labored in 349 00:22:31,493 --> 00:22:33,427 the glass-making workshop by day, 350 00:22:33,461 --> 00:22:35,928 and tended to the master's household chores by night. 351 00:22:41,435 --> 00:22:42,935 Hurry up, stupid! 352 00:22:42,969 --> 00:22:45,905 And remember, no reading. 353 00:22:50,277 --> 00:22:53,111 Until Joseph got his big break. 354 00:22:53,145 --> 00:22:57,238 Weichselberger's house collapsed. 355 00:23:15,297 --> 00:23:17,165 Maximilian, the future king of Bavaria, 356 00:23:17,199 --> 00:23:19,100 hurried to the scene of the calamity 357 00:23:19,134 --> 00:23:20,668 to see if he could help. 358 00:23:20,703 --> 00:23:23,137 Maximilian was known for 359 00:23:23,172 --> 00:23:24,772 taking an interest in his subjects, 360 00:23:24,807 --> 00:23:27,008 which was highly unusual for its time. 361 00:23:40,890 --> 00:23:44,025 In attracting the concern of the future king of Bavaria, 362 00:23:44,059 --> 00:23:45,660 young Joseph Fraunhofer 363 00:23:45,694 --> 00:23:48,496 found an aperture into a different universe. 364 00:23:48,530 --> 00:23:50,965 And not just for himself. 365 00:23:53,769 --> 00:23:55,537 Prince Maximilian gave Joseph money 366 00:23:55,571 --> 00:23:57,372 and asked his privy councilor 367 00:23:57,406 --> 00:23:58,840 to provide further help to the boy, 368 00:23:58,874 --> 00:24:01,242 should it be needed. 369 00:24:06,115 --> 00:24:08,817 Weichselberger continued to exploit him 370 00:24:08,851 --> 00:24:11,152 and prevent him from attending school. 371 00:24:11,187 --> 00:24:13,221 But the prince's councilor intervened, 372 00:24:13,255 --> 00:24:16,758 offering Joseph a position at the Optical Institute. 373 00:24:16,792 --> 00:24:21,930 This small gesture of kindness really paid off. 374 00:24:34,276 --> 00:24:37,112 By the time he was 27, 375 00:24:37,146 --> 00:24:39,381 Joseph Fraunhofer was the world's leading designer 376 00:24:39,415 --> 00:24:41,416 of high-quality lenses, 377 00:24:41,450 --> 00:24:44,119 telescopes and other optical instruments. 378 00:24:44,153 --> 00:24:48,023 His firm was housed here, in the old Benediktbeuren Abbey. 379 00:24:48,057 --> 00:24:50,225 In the early 19th century, 380 00:24:50,259 --> 00:24:53,561 this was top-secret, ultra-high technology. 381 00:24:56,599 --> 00:24:58,800 The Benedictine monks of earlier times 382 00:24:58,834 --> 00:25:00,802 had taken a vow of secrecy. 383 00:25:00,836 --> 00:25:02,804 This local tradition, 384 00:25:02,838 --> 00:25:04,305 and the ability to restrict access 385 00:25:04,340 --> 00:25:05,874 to Fraunhofer's laboratory, 386 00:25:05,908 --> 00:25:07,876 allowed him to maintain control 387 00:25:07,910 --> 00:25:10,979 of trade and state secrets. 388 00:25:16,085 --> 00:25:18,386 Fraunhofer was experimenting with prisms 389 00:25:18,421 --> 00:25:21,823 to find the best types of glass for precision lenses. 390 00:25:21,857 --> 00:25:24,559 How, he wondered, could he get a better look 391 00:25:24,593 --> 00:25:26,594 at the spectrum that a prism produced? 392 00:25:29,765 --> 00:25:33,568 Friedrich, bring me the theodolite, please. 393 00:25:33,602 --> 00:25:36,504 Okay, while Fraunhofer sets up his theodolite-- 394 00:25:36,539 --> 00:25:38,340 it's a kind of telescope-- 395 00:25:38,374 --> 00:25:41,676 I want to show you something in another part of the abbey. 396 00:25:46,315 --> 00:25:50,051 Sound waves are so beautiful to hear. 397 00:25:51,887 --> 00:25:56,591 Imagine how beautiful they'd be to see. 398 00:25:56,625 --> 00:25:59,828 You ever wondered why organ pipes have different lengths? 399 00:26:02,064 --> 00:26:03,298 I press a key... 400 00:26:05,801 --> 00:26:07,202 it sends compressed air 401 00:26:07,236 --> 00:26:08,470 into a particular pipe, 402 00:26:08,504 --> 00:26:10,305 producing sound waves. 403 00:26:10,339 --> 00:26:13,041 If we could slow the sound waves down a few hundred times, 404 00:26:13,075 --> 00:26:15,210 they would look like this. 405 00:26:18,914 --> 00:26:20,548 The length of the pipe 406 00:26:20,583 --> 00:26:22,017 determines the length of the sound wave 407 00:26:22,051 --> 00:26:23,518 that can fit inside it. 408 00:26:23,552 --> 00:26:25,620 A short pipe gives you a short sound wave. 409 00:26:27,656 --> 00:26:30,392 Short sounds waves have high pitch, or frequency. 410 00:26:35,898 --> 00:26:38,566 Let's stop the waves for a better look. 411 00:26:42,938 --> 00:26:44,873 The distance between adjacent waves 412 00:26:44,907 --> 00:26:46,675 is called the wavelength. 413 00:26:46,709 --> 00:26:49,210 A long pipe gives you a long sound wave 414 00:26:49,245 --> 00:26:51,613 with a low pitch, or low frequency. 415 00:27:43,165 --> 00:27:46,067 The medieval manuscript of this music, "Carmina Burana," 416 00:27:46,102 --> 00:27:49,270 was discovered in this very abbey. 417 00:27:52,475 --> 00:27:54,909 Sound waves can't travel through a vacuum. 418 00:27:54,944 --> 00:27:56,811 They need matter to ride on, 419 00:27:56,846 --> 00:28:00,315 like molecules of air, or water, or rock. 420 00:28:00,349 --> 00:28:02,450 But light waves fly solo. 421 00:28:02,485 --> 00:28:04,653 They can move through empty space. 422 00:28:04,687 --> 00:28:06,287 And fast-- 423 00:28:06,322 --> 00:28:09,424 a million times faster than sound waves in air. 424 00:28:09,458 --> 00:28:11,426 And the wavelengths of the light we see 425 00:28:11,460 --> 00:28:13,962 are so much shorter than sound waves. 426 00:28:13,996 --> 00:28:16,831 About 50,000 light waves 427 00:28:16,866 --> 00:28:19,300 would fit right in here. 428 00:28:20,469 --> 00:28:22,003 Oh, yeah. 429 00:28:22,038 --> 00:28:23,471 Fraunhofer. 430 00:28:30,112 --> 00:28:31,446 Just in time. 431 00:28:31,480 --> 00:28:33,114 We didn't miss it. 432 00:28:33,149 --> 00:28:35,316 Just as the wavelength of sound 433 00:28:35,351 --> 00:28:37,318 determines the pitch that we hear, 434 00:28:37,353 --> 00:28:38,820 the wavelength of light 435 00:28:38,854 --> 00:28:41,289 determines the color that we see. 436 00:28:41,323 --> 00:28:43,758 But how does a prism spread out the colors 437 00:28:43,793 --> 00:28:46,294 concealed in a beam of sunlight? 438 00:28:46,328 --> 00:28:50,265 When light travels through air or space, 439 00:28:50,299 --> 00:28:52,667 all its colors move at the same speed. 440 00:28:54,704 --> 00:28:57,472 But when it hits glass at an angle, 441 00:28:57,506 --> 00:28:59,908 the light slows down and changes direction. 442 00:29:01,477 --> 00:29:03,445 Inside the prism, 443 00:29:03,479 --> 00:29:05,480 each color moves at a different speed. 444 00:29:09,819 --> 00:29:11,619 In glass, violet light, 445 00:29:11,654 --> 00:29:13,822 which is carried by the shortest waves we see, 446 00:29:13,856 --> 00:29:15,857 slows down more than red light, 447 00:29:15,891 --> 00:29:18,326 which has the longest waves. 448 00:29:20,162 --> 00:29:22,564 These changes in speed 449 00:29:22,598 --> 00:29:25,133 pry the colors apart, 450 00:29:25,167 --> 00:29:26,968 sending their waves off 451 00:29:27,002 --> 00:29:29,404 in slightly different directions. 452 00:29:30,606 --> 00:29:32,607 That's how a prism works. 453 00:29:34,744 --> 00:29:37,011 If I seem unduly emotional about this, 454 00:29:37,046 --> 00:29:39,848 it's because Joseph Fraunhofer is about to do 455 00:29:39,882 --> 00:29:43,385 what Isaac Newton could've done, but didn't. 456 00:29:43,419 --> 00:29:45,487 And it'll have a powerful effect 457 00:29:45,521 --> 00:29:47,355 on the course of my own life. 458 00:30:10,379 --> 00:30:12,414 You are witnessing the marriage 459 00:30:12,448 --> 00:30:14,049 of physics and astronomy, 460 00:30:14,083 --> 00:30:17,952 the birth of my own field of science, 461 00:30:17,987 --> 00:30:20,422 astrophysics. 462 00:30:22,425 --> 00:30:24,192 Written in the light, 463 00:30:24,226 --> 00:30:27,629 in those vertical black lines... 464 00:30:29,065 --> 00:30:32,033 is secret code. 465 00:30:32,068 --> 00:30:34,869 Fraunhofer looked at them, and wondered... 466 00:30:34,904 --> 00:30:36,905 Why? 467 00:30:39,750 --> 00:30:43,085 A code that comes to us 468 00:30:43,120 --> 00:30:45,554 from an alien universe. 469 00:30:57,283 --> 00:30:58,530 What is the message 470 00:30:58,616 --> 00:31:02,220 written in these dark, vertical lines? 471 00:31:07,293 --> 00:31:09,360 It took a hundred years of thinking, 472 00:31:09,395 --> 00:31:12,697 questioning, searching to decipher it. 473 00:31:32,251 --> 00:31:34,385 Lovely, isn't it? 474 00:31:34,420 --> 00:31:35,954 Why? 475 00:31:35,988 --> 00:31:39,457 There are many layers to the fine structure of beauty... 476 00:31:39,492 --> 00:31:42,627 the chemistry of the Earth and its atmosphere... 477 00:31:42,661 --> 00:31:45,597 the evolution of life... 478 00:31:45,631 --> 00:31:49,200 Many distinct threads. 479 00:31:49,235 --> 00:31:52,303 Let's just examine one, at the surface... 480 00:31:52,338 --> 00:31:54,739 the colors of nature that dazzle us. 481 00:31:54,773 --> 00:31:57,876 What's really happening? 482 00:31:57,910 --> 00:31:59,777 How does the red, the blue... 483 00:31:59,812 --> 00:32:02,780 the astonishing palette of nature's colors... 484 00:32:06,785 --> 00:32:09,420 how do they happen? 485 00:32:12,091 --> 00:32:14,259 Light waves of different lengths from the Sun 486 00:32:14,293 --> 00:32:15,693 strike the Earth. 487 00:32:17,096 --> 00:32:19,130 The petals of these particular flowers 488 00:32:19,165 --> 00:32:20,732 absorb all the low-energy, 489 00:32:20,766 --> 00:32:23,001 long red wavelengths of light. 490 00:32:23,035 --> 00:32:24,736 But the petals reflect 491 00:32:24,770 --> 00:32:28,072 the shorter, high-energy blue wavelengths. 492 00:32:28,107 --> 00:32:30,842 That interaction between starlight and petal-- 493 00:32:30,876 --> 00:32:32,844 or water, or Van Gogh-- 494 00:32:32,878 --> 00:32:34,445 is what makes blue. 495 00:32:34,480 --> 00:32:36,614 The longest waves, 496 00:32:36,649 --> 00:32:38,449 the ones we see as red, 497 00:32:38,484 --> 00:32:41,052 have the lowest energy. 498 00:32:43,989 --> 00:32:46,324 Color is the way our eyes perceive 499 00:32:46,358 --> 00:32:48,226 how energetic light waves are. 500 00:32:50,062 --> 00:32:51,763 A sunset... 501 00:32:51,797 --> 00:32:53,932 a flag... 502 00:32:53,966 --> 00:32:56,367 the eyes of your beloved... 503 00:32:56,402 --> 00:32:58,136 that shiny new car. 504 00:32:58,170 --> 00:33:00,138 The feelings they inspire 505 00:33:00,172 --> 00:33:01,973 happen when something inside you 506 00:33:02,007 --> 00:33:04,476 is triggered by a particular variation 507 00:33:04,510 --> 00:33:07,979 in the frequency and energy of light waves. 508 00:33:09,748 --> 00:33:10,882 And the secret message? 509 00:33:10,916 --> 00:33:12,617 Those black vertical lines 510 00:33:12,651 --> 00:33:14,652 in Fraunhofer's spectrum? 511 00:33:14,687 --> 00:33:16,788 What makes them? 512 00:33:16,822 --> 00:33:18,990 They occur when the light waves 513 00:33:19,024 --> 00:33:21,793 of those particular colors are being absorbed. 514 00:33:21,827 --> 00:33:24,362 It happens on another level of reality, 515 00:33:24,396 --> 00:33:27,398 far smaller than the world we're used to operating in. 516 00:33:27,433 --> 00:33:30,001 To get there, we'll need to become 517 00:33:30,035 --> 00:33:32,770 ten billion times smaller than we are. 518 00:33:35,541 --> 00:33:37,909 We could pick any one of these atoms. 519 00:33:37,943 --> 00:33:41,012 But let's go for the hydrogen atom. 520 00:33:41,046 --> 00:33:43,515 The hydrogen atom is the most plentiful kind 521 00:33:43,549 --> 00:33:45,917 of atom in the cosmos. 522 00:33:45,951 --> 00:33:48,353 And the simplest. 523 00:33:55,861 --> 00:33:59,030 It has only one electron. 524 00:33:59,064 --> 00:34:01,566 And only one proton. 525 00:34:01,600 --> 00:34:03,668 We've entered the quantum realm. 526 00:34:03,702 --> 00:34:05,503 It doesn't correspond 527 00:34:05,538 --> 00:34:08,273 to ordinary human experience. 528 00:34:08,307 --> 00:34:11,509 Common sense is no help here at all. 529 00:34:11,544 --> 00:34:14,546 Take the hydrogen atom's electron, for example. 530 00:34:16,482 --> 00:34:18,716 In an atom, an electron 531 00:34:18,751 --> 00:34:20,451 doesn't exist between orbitals. 532 00:34:20,486 --> 00:34:22,253 It disappears from one orbital 533 00:34:22,288 --> 00:34:24,923 and reappears in another. 534 00:34:24,957 --> 00:34:26,758 It's as if you took an elevator from the second floor 535 00:34:26,792 --> 00:34:30,061 to the fourth floor, but ceased to exist in between. 536 00:34:30,095 --> 00:34:31,796 And another thing. 537 00:34:31,831 --> 00:34:34,766 Quantum elevators only stop at certain floors. 538 00:34:34,800 --> 00:34:38,203 The sizes of the electron orbits are strictly limited, 539 00:34:38,237 --> 00:34:41,072 and different for the atoms of every element. 540 00:34:42,608 --> 00:34:44,943 That's why the elements are different. 541 00:34:44,977 --> 00:34:46,311 The chemistry of anything is determined 542 00:34:46,345 --> 00:34:47,912 by its electron orbits. 543 00:34:47,947 --> 00:34:50,815 The force that holds an electron in orbit 544 00:34:50,850 --> 00:34:52,650 has nothing to do with gravity. 545 00:34:52,685 --> 00:34:56,221 It's a force of electrical attraction. 546 00:34:56,255 --> 00:34:58,556 The electron dances a wavy ring 547 00:34:58,591 --> 00:35:00,825 around the central nucleus of a hydrogen atom. 548 00:35:00,860 --> 00:35:03,628 And makes quantum leaps from orbit to orbit. 549 00:35:03,662 --> 00:35:04,929 Up or down. 550 00:35:04,964 --> 00:35:06,331 The larger the orbit, 551 00:35:06,365 --> 00:35:08,399 the greater the energy of an electron. 552 00:35:08,434 --> 00:35:10,802 An electron has 553 00:35:10,836 --> 00:35:12,971 to get energy to leap to a larger orbit. 554 00:35:13,005 --> 00:35:15,807 And it has to lose energy to jump back down. 555 00:35:15,841 --> 00:35:19,143 Every upward leap is caused by... 556 00:35:19,178 --> 00:35:22,580 an atom absorbing a light wave. 557 00:35:22,615 --> 00:35:26,417 But we have no idea what causes the downward leaps. 558 00:35:26,452 --> 00:35:30,021 What we do know that such leaps always produce a light wave 559 00:35:30,055 --> 00:35:32,690 whose color matches the energy difference 560 00:35:32,725 --> 00:35:34,492 between the orbitals. 561 00:35:39,398 --> 00:35:43,801 The Sun's surface radiates light waves of all colors. 562 00:35:43,836 --> 00:35:45,637 If you look at sunlight through a prism, 563 00:35:45,671 --> 00:35:47,672 you'll see its spectrum. 564 00:35:50,309 --> 00:35:53,144 When you magnify the spectrum with a telescope, 565 00:35:53,179 --> 00:35:55,046 as Joseph Fraunhofer did, 566 00:35:55,080 --> 00:35:56,648 you raise the curtain 567 00:35:56,682 --> 00:35:59,884 on the electron dance within the atom. 568 00:35:59,919 --> 00:36:02,120 When the energy of the electron flags, 569 00:36:02,154 --> 00:36:03,821 and it drops to a lower orbital, 570 00:36:03,856 --> 00:36:06,224 the light wave it emits scatters. 571 00:36:06,258 --> 00:36:08,660 Most of it doesn't reach us. 572 00:36:08,694 --> 00:36:10,228 That leaves a dark gap 573 00:36:10,262 --> 00:36:13,164 or black vertical line in the spectrum. 574 00:36:13,199 --> 00:36:15,733 These dark lines are the shadows 575 00:36:15,768 --> 00:36:17,368 cast by hydrogen atoms 576 00:36:17,403 --> 00:36:19,337 in the atmosphere of the Sun. 577 00:36:19,371 --> 00:36:22,073 Sodium atoms cast different shadows. 578 00:36:22,107 --> 00:36:25,176 Their electrons dance to a different tune. 579 00:36:25,211 --> 00:36:27,078 A grain of table salt is composed 580 00:36:27,112 --> 00:36:28,913 of sodium and chlorine atoms. 581 00:36:28,948 --> 00:36:31,382 Ten million billion of them 582 00:36:31,417 --> 00:36:33,384 doing their crazy dances 583 00:36:33,419 --> 00:36:36,254 in a single grain of salt. 584 00:36:36,288 --> 00:36:39,190 And a single iron atom with 26 electrons 585 00:36:39,225 --> 00:36:41,559 is like a great big production number 586 00:36:41,594 --> 00:36:44,896 in a Broadway musical. 587 00:36:47,299 --> 00:36:51,202 When you look at a star with a spectroscope, 588 00:36:51,237 --> 00:36:53,671 you see the dark lines from all the elements 589 00:36:53,706 --> 00:36:55,340 in its atmosphere. 590 00:36:55,374 --> 00:36:57,242 Show me the spectrum of anything, 591 00:36:57,276 --> 00:37:00,044 whether here on Earth or from a distant star, 592 00:37:00,079 --> 00:37:03,114 and I'll tell you what it's made of. 593 00:37:03,148 --> 00:37:06,751 Fraunhofer's lines are the atomic signatures 594 00:37:06,785 --> 00:37:10,755 of the elements writ large across the cosmos. 595 00:37:10,789 --> 00:37:12,857 As with every other major revelation 596 00:37:12,892 --> 00:37:15,393 in the history of science, it opened the way 597 00:37:15,427 --> 00:37:18,396 to newer and deeper mysteries. 598 00:37:18,430 --> 00:37:21,399 And to the revelation that there were 599 00:37:21,433 --> 00:37:24,469 many more secrets hiding in the light. 600 00:37:40,472 --> 00:37:43,408 When Joseph Fraunhofer combined a prism with a telescope 601 00:37:43,410 --> 00:37:45,677 and turned it toward the skies, 602 00:37:45,679 --> 00:37:49,180 he brought the stars much closer to us. 603 00:38:00,159 --> 00:38:02,894 When he was only 39, 604 00:38:02,896 --> 00:38:05,063 he contracted a fatal illness. 605 00:38:05,065 --> 00:38:07,732 Perhaps as a result of his early and long-term exposure 606 00:38:07,734 --> 00:38:10,668 to the toxic chemicals of glassmaking. 607 00:38:10,670 --> 00:38:14,672 You never know where the next genius will come from. 608 00:38:18,611 --> 00:38:23,114 How many of them do we leave in the rubble? 609 00:38:23,116 --> 00:38:26,384 The prince and his kingdom were immeasurably enriched 610 00:38:26,386 --> 00:38:29,754 by that act of kindness to a poor orphan. 611 00:38:29,756 --> 00:38:32,190 Fraunhofer's discoveries transformed Bavaria 612 00:38:32,192 --> 00:38:36,461 from a rural backwater to a technological powerhouse. 613 00:38:38,297 --> 00:38:40,732 As he lay dying, the government was desperate 614 00:38:40,734 --> 00:38:43,635 to preserve every shred of his precious knowledge 615 00:38:43,637 --> 00:38:45,937 about the high technology of optical glass. 616 00:38:48,974 --> 00:38:50,909 But it could only be divulged to a person 617 00:38:50,911 --> 00:38:53,111 with top security clearance-- 618 00:38:53,113 --> 00:38:54,879 the director of the mint. 619 00:39:11,964 --> 00:39:14,565 The government kept Fraunhofer's technology 620 00:39:14,567 --> 00:39:16,467 for making perfect optical glass 621 00:39:16,469 --> 00:39:19,737 a State secret for another hundred years. 622 00:39:19,739 --> 00:39:21,739 This would prove to be a major obstacle 623 00:39:21,774 --> 00:39:24,242 for someone we'll meet later in our journey. 624 00:39:24,276 --> 00:39:26,811 But Fraunhofer would allow no such secrecy 625 00:39:26,845 --> 00:39:29,414 where his pure scientific research was concerned. 626 00:39:29,448 --> 00:39:33,051 He knew that science requires openness to flourish; 627 00:39:33,085 --> 00:39:37,121 that our understanding of nature belongs to the world. 628 00:39:37,156 --> 00:39:40,058 As soon as Fraunhofer discovered the spectral lines, 629 00:39:40,092 --> 00:39:42,627 he published everything he knew about them. 630 00:39:42,661 --> 00:39:45,463 And the reverberations of his momentous discovery 631 00:39:45,497 --> 00:39:48,266 echo still. 632 00:39:51,437 --> 00:39:55,406 His spectral lines revealed that the visible cosmos 633 00:39:55,441 --> 00:39:58,710 is all made of the same elements. 634 00:40:01,747 --> 00:40:04,215 The planets... 635 00:40:12,357 --> 00:40:14,826 The stars... 636 00:40:19,198 --> 00:40:21,332 The galaxies... 637 00:40:25,571 --> 00:40:28,573 We, ourselves, and all of life... 638 00:40:35,247 --> 00:40:38,783 The same star stuff. 639 00:40:44,223 --> 00:40:45,890 He made it possible for us to know 640 00:40:45,924 --> 00:40:48,392 what's in the atmosphere of other worlds. 641 00:40:50,863 --> 00:40:54,499 And in galaxies millions of light-years away. 642 00:40:54,533 --> 00:40:56,534 Spectral lines revealed not only the composition 643 00:40:56,568 --> 00:40:59,036 of far-off objects, but also their motion 644 00:40:59,071 --> 00:41:01,239 towards or away from us. 645 00:41:01,273 --> 00:41:04,342 Using them, we discovered that our universe is expanding. 646 00:41:04,376 --> 00:41:07,945 But perhaps the greatest revelation of spectroscopy 647 00:41:07,980 --> 00:41:10,781 is the discovery of the thing it cannot see. 648 00:41:16,789 --> 00:41:18,956 A hidden universe of dark matter 649 00:41:18,991 --> 00:41:22,226 six times more massive than the familiar cosmos. 650 00:41:22,261 --> 00:41:24,428 It's made of some mysterious substance 651 00:41:24,463 --> 00:41:29,033 that does not emit, reflect or absorb any kind of light. 652 00:41:29,067 --> 00:41:31,536 We only know it's there because of its gravity, 653 00:41:31,570 --> 00:41:33,638 which pulls on all the galaxies 654 00:41:33,672 --> 00:41:36,407 and speeds up the visible stars within them. 655 00:41:40,412 --> 00:41:43,881 There are many more kinds of light than our eyes can see. 656 00:41:43,916 --> 00:41:47,318 Confining our perception of nature to visible light 657 00:41:47,352 --> 00:41:49,654 is like listening to music 658 00:41:49,688 --> 00:41:51,255 in only one octave. 659 00:41:53,826 --> 00:41:55,827 There are so many more. 660 00:41:55,861 --> 00:41:57,795 They differ only in wavelength, 661 00:41:57,830 --> 00:41:59,931 but over a huge range. 662 00:41:59,965 --> 00:42:02,533 For instance, infrared light... 663 00:42:07,873 --> 00:42:11,008 the kind that William Herschel discovered 664 00:42:11,043 --> 00:42:12,810 Or X-ray light. 665 00:42:17,883 --> 00:42:19,951 Or radio light. 666 00:42:24,690 --> 00:42:26,524 Or in gamma-ray light. 667 00:42:32,331 --> 00:42:35,600 These are not just different ways of seeing the same thing. 668 00:42:35,634 --> 00:42:37,201 These other kinds of light 669 00:42:37,236 --> 00:42:40,838 reveal different objects and phenomena in the cosmos. 670 00:42:40,873 --> 00:42:44,041 In gamma-ray light, for example, we can see mysterious explosions 671 00:42:44,076 --> 00:42:45,810 in distant galaxies 672 00:42:45,844 --> 00:42:48,145 that we would otherwise miss. 673 00:42:51,083 --> 00:42:53,951 And in microwave light, we can see all the way back 674 00:42:53,986 --> 00:42:56,387 to the birth of the universe. 675 00:42:58,924 --> 00:43:02,226 We have only just opened our eyes.