1 00:01:33,712 --> 00:01:37,014 The age and size of the cosmos 2 00:01:37,048 --> 00:01:40,150 are written in light. 3 00:01:40,185 --> 00:01:45,022 The nature of beauty and the substance of the stars, 4 00:01:45,056 --> 00:01:48,425 the laws of space and time... 5 00:01:48,460 --> 00:01:51,428 they were there all along, 6 00:01:51,463 --> 00:01:53,464 but we never saw them... 7 00:01:53,498 --> 00:01:57,334 until we devised a more powerful way of seeing. 8 00:01:57,369 --> 00:02:01,038 The story of this awakening has many beginnings 9 00:02:01,072 --> 00:02:03,207 and no ending. 10 00:02:03,241 --> 00:02:06,443 Its heroes come from many times and places-- 11 00:02:06,478 --> 00:02:09,280 an Ancient Chinese philosopher, 12 00:02:09,314 --> 00:02:12,983 a wizard who amazed the caliphs of 11th-century Iraq, 13 00:02:13,018 --> 00:02:17,888 a poor German orphan enslaved to a harsh master. 14 00:02:17,922 --> 00:02:20,357 Each one brought us a little closer 15 00:02:20,392 --> 00:02:24,595 to unlocking the secrets hidden in light. 16 00:02:27,232 --> 00:02:30,668 Most of their names are forever lost to us, 17 00:02:30,702 --> 00:02:35,205 but somewhere, long ago, someone glanced up 18 00:02:35,240 --> 00:02:39,610 to see light perform one of its magic tricks. 19 00:03:00,932 --> 00:03:01,932 Who knows? 20 00:03:01,967 --> 00:03:03,734 Maybe that quirk of light 21 00:03:03,768 --> 00:03:05,903 inspired the very first artist. 22 00:03:18,149 --> 00:03:21,185 Where did all this come from? 23 00:03:21,219 --> 00:03:24,788 How did we evolve from small wandering bands 24 00:03:24,823 --> 00:03:26,957 of hunters and gatherers living beneath the stars 25 00:03:26,992 --> 00:03:30,761 to become the builders of a global civilization? 26 00:03:30,795 --> 00:03:34,231 How did we get from there to here? 27 00:03:34,265 --> 00:03:36,066 There's no one answer. 28 00:03:36,101 --> 00:03:38,769 Climate change, the domestication of fire, 29 00:03:38,803 --> 00:03:43,307 the invention of tools, language, agriculture 30 00:03:43,341 --> 00:03:46,610 all played a role. 31 00:03:46,645 --> 00:03:49,279 Maybe there was something else, too. 32 00:03:49,314 --> 00:03:52,449 In China, more than 2,000 years ago, 33 00:03:52,484 --> 00:03:55,653 a philosopher named Mo Tze is said to have observed 34 00:03:55,687 --> 00:03:58,055 that light could be made to paint a picture 35 00:03:58,089 --> 00:04:00,324 inside a locked treasure room. 36 00:04:00,358 --> 00:04:05,796 This was the description of the first camera... 37 00:04:05,830 --> 00:04:07,931 the camera obscura, 38 00:04:07,966 --> 00:04:10,334 the prototype of all image-forming cameras, 39 00:04:10,368 --> 00:04:13,637 including the one that's bringing you this picture. 40 00:04:13,672 --> 00:04:16,273 Taking advantage of this funny thing that light does 41 00:04:16,308 --> 00:04:21,278 resulted in what could be called the first movie. 42 00:04:21,313 --> 00:04:27,084 Mo Tze, master of light, worked against all forms of darkness. 43 00:04:27,118 --> 00:04:28,852 A military genius 44 00:04:28,887 --> 00:04:32,022 who only used his talents to prevent violence, 45 00:04:32,057 --> 00:04:34,024 he was legendary for traveling 46 00:04:34,059 --> 00:04:36,160 among the kingdoms of the warring states, 47 00:04:36,194 --> 00:04:37,928 employing ingenious strategies 48 00:04:37,963 --> 00:04:39,997 to talk kings out of going to war. 49 00:04:40,031 --> 00:04:43,600 He was one of the first to dream of universal love 50 00:04:43,635 --> 00:04:46,704 and an end to poverty and other forms of inequality; 51 00:04:46,738 --> 00:04:50,674 of government for the people... 52 00:04:50,709 --> 00:04:53,143 and to argue against blind obedience 53 00:04:53,178 --> 00:04:54,545 to ritual and authority. 54 00:04:54,579 --> 00:04:56,146 In his writings, you can find 55 00:04:56,181 --> 00:04:59,883 early stirrings of the scientific approach. 56 00:04:59,918 --> 00:05:02,853 By Mo Tze's time, the Chinese had already been recording 57 00:05:02,887 --> 00:05:06,223 their thoughts in books for at least a thousand years. 58 00:05:06,257 --> 00:05:09,193 Still, our knowledge of him is only fragmentary. 59 00:05:09,227 --> 00:05:11,662 It consists largely of the collection of essays 60 00:05:11,696 --> 00:05:13,364 attributed to him and his disciples. 61 00:05:13,398 --> 00:05:16,533 In one of them, entitled "Against Fate," 62 00:05:16,568 --> 00:05:19,670 a three-pronged test for every doctrine is proposed. 63 00:05:19,704 --> 00:05:22,206 Question its basis-- 64 00:05:22,240 --> 00:05:23,907 ask if it can be verified 65 00:05:23,942 --> 00:05:26,477 by the sights and senses of common people-- 66 00:05:26,511 --> 00:05:28,245 ask how it is to be applied 67 00:05:28,279 --> 00:05:30,614 and if it will benefit the greatest number. 68 00:05:35,053 --> 00:05:37,521 Mo Tze was extremely popular, 69 00:05:37,555 --> 00:05:39,857 but a few hundred years after his death, 70 00:05:39,891 --> 00:05:42,826 Qin Shi Huang, the first emperor, 71 00:05:42,861 --> 00:05:45,896 and unifier of China, took power. 72 00:05:45,930 --> 00:05:48,499 He took a continent and turned it into a nation 73 00:05:48,533 --> 00:05:51,935 that now bears his name... China. 74 00:05:54,973 --> 00:05:59,443 Most of us know Emperor Qin for the army of 7,000 75 00:05:59,477 --> 00:06:02,780 terra cotta warriors that guard his tomb. 76 00:06:04,649 --> 00:06:07,584 In Emperor Qin's drive 77 00:06:07,619 --> 00:06:10,220 to consolidate his far-flung empire, 78 00:06:10,255 --> 00:06:11,922 he took drastic measures 79 00:06:11,957 --> 00:06:14,425 to standardize everything within it. 80 00:06:14,459 --> 00:06:17,394 This included mandating a single coinage, 81 00:06:17,429 --> 00:06:19,964 making uniform all weights and measures, 82 00:06:19,998 --> 00:06:23,801 the widths of carts and roads, as well as the precise way 83 00:06:23,835 --> 00:06:26,036 the Chinese language was to be written, 84 00:06:26,071 --> 00:06:31,108 including what you were allowed to write and think. 85 00:06:31,142 --> 00:06:33,911 Emperor Qin's philosophy-- the only one permitted-- 86 00:06:33,945 --> 00:06:35,546 was called "legalism," 87 00:06:35,580 --> 00:06:38,148 which is just what it sounded like, 88 00:06:38,183 --> 00:06:41,585 do as the law says... or else. 89 00:06:42,020 --> 00:06:44,654 It's a philosophy that's not highly conducive 90 00:06:44,689 --> 00:06:46,690 to questioning authority. 91 00:06:51,763 --> 00:06:54,565 ...that all the books of the hundred schools of thought 92 00:06:54,599 --> 00:06:56,233 shall be be burned, 93 00:06:56,267 --> 00:06:59,670 that anyone who uses history to criticize the present 94 00:06:59,704 --> 00:07:01,972 shall have his family executed. 95 00:07:04,009 --> 00:07:06,110 The works of MoTze and Confucius 96 00:07:06,144 --> 00:07:08,345 and other philosophers were destroyed 97 00:07:08,380 --> 00:07:10,347 in the world's first book burning. 98 00:07:10,382 --> 00:07:12,950 Hundreds of scholars bravely resisted 99 00:07:12,984 --> 00:07:15,686 by trying to preserve the forbidden books. 100 00:07:15,720 --> 00:07:18,322 They were buried alive in the capitol. 101 00:07:20,058 --> 00:07:23,861 Science needs the light of free expression to flourish. 102 00:07:23,895 --> 00:07:27,264 It depends on the fearless questioning of authority, 103 00:07:27,299 --> 00:07:29,867 the open exchange of ideas. 104 00:07:29,901 --> 00:07:33,604 Sparks of curiosity in the writings of Mo Tze 105 00:07:33,638 --> 00:07:37,374 and his disciples were effectively stomped out. 106 00:07:37,409 --> 00:07:42,012 It would be another thousand years before the next movie. 107 00:07:43,915 --> 00:07:46,150 Luckily, our Ship of the Imagination 108 00:07:46,184 --> 00:07:50,187 can take us anywhere in space... and time. 109 00:07:57,854 --> 00:08:00,522 The ancient Chinese and Greeks observed 110 00:08:00,557 --> 00:08:02,191 that light could be made 111 00:08:02,225 --> 00:08:05,027 to do wonderful things-- but no one asked that question 112 00:08:05,061 --> 00:08:10,332 favored by small children and geniuses alike. Why? 113 00:08:10,367 --> 00:08:13,402 Until a thousand years ago... 114 00:08:18,508 --> 00:08:20,843 In the city of Basra, Iraq, 115 00:08:20,877 --> 00:08:22,845 there lived another master of light. 116 00:08:22,879 --> 00:08:28,217 Ibn al-Hazen had a passionate desire to understand nature. 117 00:08:28,251 --> 00:08:30,352 He questioned everything, 118 00:08:30,387 --> 00:08:34,323 especially those things that everyone else took for granted. 119 00:08:36,259 --> 00:08:39,461 "How do we see?" he asked. 120 00:08:39,496 --> 00:08:41,864 Some of the great authorities who came before him 121 00:08:41,898 --> 00:08:45,467 had taught that rays come out of our eyes and travel 122 00:08:45,502 --> 00:08:49,838 to the objects we see before returning to our eyes. 123 00:08:49,873 --> 00:08:53,742 But al-Hazen reasoned that the stars were too far distant 124 00:08:53,777 --> 00:08:56,345 for something in our eyes to travel all the way to them 125 00:08:56,379 --> 00:08:59,014 and back in the blink of an eye. 126 00:08:59,049 --> 00:09:02,685 Excellent reasoning, but al-Hazen didn't stop there. 127 00:09:02,719 --> 00:09:06,989 He searched for ways to compel nature to divulge her secrets. 128 00:09:07,023 --> 00:09:10,325 His culture was open to new ideas and questioning. 129 00:09:10,360 --> 00:09:12,828 It was the golden age of science 130 00:09:12,862 --> 00:09:15,064 in the Islamic world. 131 00:09:15,098 --> 00:09:18,534 One that stretched from Cordoba in Spain 132 00:09:18,568 --> 00:09:22,171 all the way to Samarkand in Central Asia. 133 00:09:22,205 --> 00:09:25,207 Christian and Jewish scholars were honored guests 134 00:09:25,241 --> 00:09:27,943 at the research institutes of Baghdad, Cairo, 135 00:09:27,977 --> 00:09:30,512 and other Islamic capitols. 136 00:09:30,547 --> 00:09:34,083 Instead of burning books, the caliphs sent emissaries 137 00:09:34,117 --> 00:09:37,052 around the world in search of books. 138 00:09:50,834 --> 00:09:55,237 The caliphs lavishly funded projects to translate, study, 139 00:09:55,271 --> 00:09:57,473 and preserve them for future generations. 140 00:09:57,507 --> 00:10:00,442 Much of the light of Ancient Greek science would have been 141 00:10:00,477 --> 00:10:02,911 permanently extinguished without their efforts. 142 00:10:02,946 --> 00:10:05,748 The reawakening to science that took place in Europe, 143 00:10:05,782 --> 00:10:08,817 hundreds of years later, was kindled by a flame 144 00:10:08,852 --> 00:10:10,085 that had been long tended 145 00:10:10,120 --> 00:10:12,988 by Islamic scholars and scientists. 146 00:10:13,023 --> 00:10:16,558 The Arabs also imported ideas from India to the West, 147 00:10:16,593 --> 00:10:19,161 including the so-called Arabic numerals 148 00:10:19,195 --> 00:10:21,463 that we all use today, 149 00:10:21,498 --> 00:10:24,299 and the concept of zero... 150 00:10:26,970 --> 00:10:28,437 which comes in handy 151 00:10:28,471 --> 00:10:31,907 when you want to write "billions and billions." 152 00:10:31,941 --> 00:10:34,910 Arabic astronomy was so influential, 153 00:10:34,944 --> 00:10:36,979 that we still call most of the bright stars 154 00:10:37,013 --> 00:10:38,814 by their Arabic names. 155 00:10:38,848 --> 00:10:43,919 And the "al's" in algebra, algorithm, alchemy, and alcohol 156 00:10:43,953 --> 00:10:45,654 are just some of the traces left 157 00:10:45,689 --> 00:10:50,159 from the time when Arabic was the language of science. 158 00:10:52,062 --> 00:10:54,797 In the 11th century, Ibn al-Hazen set about trying 159 00:10:54,831 --> 00:10:58,867 to test his ideas about light and how we see. 160 00:10:58,902 --> 00:11:02,137 So we devised an experiment to determine how light moves. 161 00:11:02,172 --> 00:11:04,540 We erected a tent in full daylight 162 00:11:04,574 --> 00:11:07,676 and sealed it tightly so that only a single ray of light 163 00:11:07,711 --> 00:11:10,446 could pierce its inner darkness. 164 00:11:10,480 --> 00:11:12,781 With little more than his brains 165 00:11:12,816 --> 00:11:15,050 and a straight piece of wood-- a ruler-- 166 00:11:15,085 --> 00:11:16,952 al-Hazen had accomplished a great leap forward 167 00:11:16,986 --> 00:11:18,520 in the history of science. 168 00:11:18,555 --> 00:11:22,558 He discovered that light moves in straight lines. 169 00:11:27,731 --> 00:11:29,698 But he was just getting started. 170 00:11:29,733 --> 00:11:33,135 Al-Hazen figured out that the key to forming any image-- 171 00:11:33,169 --> 00:11:36,205 whether you're talking about an eye or camera obscura-- 172 00:11:36,239 --> 00:11:38,907 is a small opening to restrict the light that can enter 173 00:11:38,942 --> 00:11:40,809 an otherwise darkened chamber. 174 00:11:40,844 --> 00:11:43,712 That aperture excludes the chaos 175 00:11:43,747 --> 00:11:46,415 of extraneous light rays that surround us. 176 00:11:46,449 --> 00:11:48,083 The smaller the aperture, 177 00:11:48,118 --> 00:11:50,653 the fewer directions that light can come from. 178 00:11:50,687 --> 00:11:52,855 And that makes the image sharper. 179 00:11:52,889 --> 00:11:55,657 So instead of being blinded by the light, 180 00:11:55,692 --> 00:11:58,861 we can see everything it has to show us. 181 00:11:58,895 --> 00:12:02,197 Al-Hazen made his own camera obscura 182 00:12:02,232 --> 00:12:04,266 and dazzled the caliphs. 183 00:12:04,300 --> 00:12:07,369 A camera obscura works best in bright light. 184 00:12:07,404 --> 00:12:11,206 The stars of the night sky are way too dim for this. 185 00:12:11,241 --> 00:12:14,543 We somehow need a bigger opening to collect light, 186 00:12:14,577 --> 00:12:17,012 but we also need to maintain focus. 187 00:12:17,047 --> 00:12:19,682 A telescope collects light 188 00:12:19,716 --> 00:12:22,017 from any spot in its field of view 189 00:12:22,052 --> 00:12:25,020 across the entire lens or mirror, 190 00:12:25,055 --> 00:12:28,757 an opening much larger than the camera obscura hole. 191 00:12:28,792 --> 00:12:32,695 This is one of the first telescopes... 192 00:12:32,729 --> 00:12:36,799 the one that Galileo looked through in 1609. 193 00:12:36,833 --> 00:12:41,070 With it, he pulled aside the heavy curtain of night 194 00:12:41,104 --> 00:12:44,006 and began to discover the cosmos. 195 00:12:56,619 --> 00:12:58,620 The lens made it possible 196 00:12:58,655 --> 00:13:01,724 for a telescope to have a much larger light-collecting area 197 00:13:01,758 --> 00:13:04,059 than our eyes have. 198 00:13:04,094 --> 00:13:07,496 Big buckets catch more rain than small ones. 199 00:13:07,530 --> 00:13:10,432 Modern telescopes have larger collecting areas, 200 00:13:10,467 --> 00:13:12,134 highly sensitive detectors, 201 00:13:12,168 --> 00:13:15,070 and they track the same object for hours at a time 202 00:13:15,105 --> 00:13:18,440 to accumulate as much of its light as possible. 203 00:13:18,475 --> 00:13:21,243 Space-based telescopes such as the Hubble, 204 00:13:21,277 --> 00:13:23,112 have captured light from the most distant 205 00:13:23,146 --> 00:13:24,780 and ancient galaxies, 206 00:13:24,814 --> 00:13:27,983 giving us vastly clearer pictures of the cosmos. 207 00:13:29,619 --> 00:13:33,322 Al-Hazen discovered how images are formed by light, 208 00:13:33,356 --> 00:13:35,691 but that was far from his greatest achievement. 209 00:13:35,725 --> 00:13:38,427 Ibn al-Hazen was the first person ever 210 00:13:38,461 --> 00:13:41,130 to set down the rules of science. 211 00:13:41,164 --> 00:13:43,665 He created an error-correcting mechanism, 212 00:13:43,700 --> 00:13:46,168 a systematic and relentless way 213 00:13:46,202 --> 00:13:48,837 to sift out misconceptions in our thinking. 214 00:13:48,872 --> 00:13:53,842 Finding truth is difficult... 215 00:13:53,877 --> 00:13:56,845 and the road to it is rough. 216 00:13:56,880 --> 00:13:59,148 As seekers after truth, 217 00:13:59,182 --> 00:14:02,284 you will be wise to withhold judgment and not simply put 218 00:14:02,318 --> 00:14:05,187 your trust in the writings of the ancients. 219 00:14:05,221 --> 00:14:09,024 You must question and critically examine those writings 220 00:14:09,059 --> 00:14:11,560 from every side. 221 00:14:11,594 --> 00:14:14,830 You must submit only to argument and experiment 222 00:14:14,864 --> 00:14:18,233 and not to the sayings of any person. 223 00:14:18,268 --> 00:14:20,803 For every human being is vulnerable 224 00:14:20,837 --> 00:14:23,505 to all kinds of imperfection. 225 00:14:23,540 --> 00:14:25,974 As seekers after truth, 226 00:14:26,009 --> 00:14:28,343 we must also suspect and question 227 00:14:28,378 --> 00:14:31,980 our own ideas as we perform our investigations, 228 00:14:32,015 --> 00:14:36,919 to avoid falling into prejudice or careless thinking. 229 00:14:36,953 --> 00:14:42,191 Take this course, and truth will be revealed to you. 230 00:14:59,075 --> 00:15:02,244 This is the method of science. 231 00:15:02,278 --> 00:15:05,080 So powerful that it's carried our robotic emissaries 232 00:15:05,115 --> 00:15:08,550 to the edge of the solar system and beyond. 233 00:15:10,286 --> 00:15:12,588 It has doubled our lifespan, 234 00:15:12,622 --> 00:15:14,389 made the lost worlds of the past 235 00:15:14,424 --> 00:15:16,425 come alive. 236 00:15:17,827 --> 00:15:20,062 Science has enabled us to predict events 237 00:15:20,096 --> 00:15:22,564 in the distant future... 238 00:15:22,599 --> 00:15:26,068 and to communicate with each other at the speed of light, 239 00:15:26,102 --> 00:15:28,704 as I am with you, right at this moment. 240 00:15:28,738 --> 00:15:30,773 This way of thinking has given us powers 241 00:15:30,807 --> 00:15:34,443 that al-Hazen himself would have regarded as wizardry. 242 00:15:37,947 --> 00:15:42,317 But it was he who put us on this rough, endless road. 243 00:15:44,187 --> 00:15:47,055 And now it has taken us to a place 244 00:15:47,090 --> 00:15:51,794 where even light itself is enshrouded in darkness. 245 00:16:00,094 --> 00:16:02,229 Light has properties unlike anything else 246 00:16:02,263 --> 00:16:04,131 in the realm of human existence. 247 00:16:04,165 --> 00:16:06,300 Take the speed of light. 248 00:16:06,334 --> 00:16:08,435 The basic particle of light, the photon, 249 00:16:08,469 --> 00:16:11,138 is born traveling at the speed of light 250 00:16:11,172 --> 00:16:13,941 as it emerges from an atom or a molecule. 251 00:16:13,975 --> 00:16:16,109 A photon never knows any other speed, 252 00:16:16,144 --> 00:16:18,946 and we've not found another phenomenon that accelerates 253 00:16:18,980 --> 00:16:21,915 from zero to top speed instantaneously. 254 00:16:21,950 --> 00:16:24,151 Nothing else could move as fast. 255 00:16:24,185 --> 00:16:26,820 When we try to accelerate other particles closer and closer 256 00:16:26,854 --> 00:16:29,556 to the speed of light, they resist more and more, 257 00:16:29,591 --> 00:16:31,325 as though they're getting heavier and heavier. 258 00:16:31,359 --> 00:16:32,793 No experiment yet devised 259 00:16:32,827 --> 00:16:36,830 has ever made a particle move as fast as light. 260 00:16:43,504 --> 00:16:46,139 What was that? 261 00:16:46,174 --> 00:16:48,342 You hear something? 262 00:16:48,376 --> 00:16:50,510 Where was I? Oh, yeah. 263 00:16:50,545 --> 00:16:54,615 I don't know anything else in life that behaves like light. 264 00:16:54,649 --> 00:16:58,085 I cannot reconcile its strange properties 265 00:16:58,119 --> 00:17:00,754 with everything else my senses tell me. 266 00:17:00,788 --> 00:17:03,757 Our urge to trust our senses overpowers 267 00:17:03,791 --> 00:17:05,859 what our measuring devices tell us about 268 00:17:05,894 --> 00:17:07,794 the actual nature of reality. 269 00:17:07,829 --> 00:17:09,997 Our senses work fine for life-size objects 270 00:17:10,031 --> 00:17:11,832 moving at mammal speeds, 271 00:17:11,866 --> 00:17:16,470 but are ill-adapted for the wonderland laws of lightspeed. 272 00:17:20,642 --> 00:17:24,011 We don't even know why there's a cosmic speed limit. 273 00:17:24,045 --> 00:17:27,481 Time stands still when you're traveling at the speed of light. 274 00:17:27,515 --> 00:17:29,983 What is light, anyway? 275 00:17:33,521 --> 00:17:37,024 Isaac Newton's enduring fascination with light 276 00:17:37,058 --> 00:17:39,226 began when he was a child... 277 00:17:41,663 --> 00:17:44,097 in this very house. 278 00:17:49,170 --> 00:17:53,340 By the time he was in his 20s, Newton became the first person 279 00:17:53,374 --> 00:17:56,543 to decipher the mystery of the rainbow. 280 00:18:00,248 --> 00:18:03,550 Newton discovered that some light, or white light, 281 00:18:03,585 --> 00:18:06,553 is a mixture of all the colors of the rainbow. 282 00:18:09,090 --> 00:18:11,158 Major discovery. 283 00:18:11,192 --> 00:18:13,727 He named the displays of colors a "spectrum" 284 00:18:13,761 --> 00:18:18,031 from the Latin for "phantom" or "apparition." 285 00:18:30,278 --> 00:18:32,246 Begging your pardon, Master Newton, 286 00:18:32,280 --> 00:18:34,982 the cook frets that your dinner will spoil, sir. 287 00:18:37,886 --> 00:18:40,053 No, Isaac, don't put the magnifying glass down! 288 00:18:40,088 --> 00:18:43,857 Something even more amazing is hidden in the light-- 289 00:18:43,892 --> 00:18:46,393 a code, a key to the cosmos. 290 00:18:53,167 --> 00:18:57,070 Isaac Newton didn't miss much, but that one was a beaut. 291 00:18:57,105 --> 00:19:00,207 He just walked right past the door to a hidden universe; 292 00:19:00,241 --> 00:19:04,278 a door that would not swing open again for another 150 years. 293 00:19:04,312 --> 00:19:06,613 It would fall on another scientist, 294 00:19:06,648 --> 00:19:08,315 working in the year 1800, 295 00:19:08,349 --> 00:19:10,317 to stumble on a piece of evidence 296 00:19:10,351 --> 00:19:13,353 for the unseen worlds that surround us. 297 00:19:16,925 --> 00:19:19,358 By night, William Herschel scanned the heavens 298 00:19:19,392 --> 00:19:21,861 with the largest telescope of his time. 299 00:19:21,895 --> 00:19:24,831 By day, Herschel performed experiments. 300 00:19:24,865 --> 00:19:27,500 From Newton's earlier work, it was known that sunlight 301 00:19:27,534 --> 00:19:29,902 is a blend of different colors. 302 00:19:29,937 --> 00:19:32,304 And everyone knew, just from being outside, 303 00:19:32,339 --> 00:19:34,539 that sunlight carries heat. 304 00:19:36,075 --> 00:19:38,076 William Herschel asked 305 00:19:38,110 --> 00:19:40,679 whether some colors of light carry more heat than others. 306 00:19:40,713 --> 00:19:44,816 The nature of scientific genius is to question 307 00:19:44,851 --> 00:19:47,652 what the rest of us take for granted... 308 00:19:47,687 --> 00:19:50,253 and then do the experiment. 309 00:19:52,290 --> 00:19:55,726 The thermometer that Herschel placed outside the spectrum 310 00:19:55,760 --> 00:19:57,761 was his control. 311 00:19:59,464 --> 00:20:01,365 The control in any experiment 312 00:20:01,399 --> 00:20:04,034 always lacks the factor being tested. 313 00:20:04,068 --> 00:20:06,168 That way, you know if what you're testing is 314 00:20:06,203 --> 00:20:08,304 really the thing responsible for the observation. 315 00:20:09,439 --> 00:20:10,740 In Herschel's experiment, 316 00:20:10,774 --> 00:20:12,375 the relationship between 317 00:20:12,409 --> 00:20:13,776 color and temperature was being tested, 318 00:20:13,811 --> 00:20:16,880 and so his control was a thermometer 319 00:20:16,914 --> 00:20:18,581 over the part of the white sheet 320 00:20:18,616 --> 00:20:21,917 that was not illuminated by sunlight at all. 321 00:20:24,253 --> 00:20:25,787 There's that sound again. 322 00:20:25,822 --> 00:20:28,557 What is that? 323 00:20:34,296 --> 00:20:36,798 Okay, red light is warmer than blue light. 324 00:20:36,833 --> 00:20:41,903 Interesting discovery, but not exactly revolutionary. 325 00:21:03,424 --> 00:21:07,126 No, there's nothing wrong with your thermometer. 326 00:21:07,161 --> 00:21:10,529 You've just discovered a new kind of light. 327 00:21:19,372 --> 00:21:22,441 Herschel was the first to detect this unseen presence 328 00:21:22,475 --> 00:21:25,677 lurking just below the red end of the spectrum. 329 00:21:25,711 --> 00:21:28,613 That's why it came to be called "infrared." 330 00:21:28,647 --> 00:21:30,815 "Infra" is Latin for the word "below." 331 00:21:30,849 --> 00:21:32,416 It's invisible. 332 00:21:32,451 --> 00:21:34,819 Our eyes are not sensitive to this kind of light, 333 00:21:34,853 --> 00:21:37,722 but our skin is-- we feel it as heat. 334 00:21:37,756 --> 00:21:39,557 Now, that's a really big discovery. 335 00:21:39,592 --> 00:21:41,992 But far greater secrets were still hiding 336 00:21:42,026 --> 00:21:44,494 deep inside the light. 337 00:21:50,384 --> 00:21:52,418 At about the same time that William Herschel 338 00:21:52,452 --> 00:21:55,353 was discovering infrared light in his parlor in England, 339 00:21:55,388 --> 00:21:57,856 a young boy named Joseph Fraunhofer 340 00:21:57,891 --> 00:22:00,358 was trapped in hopeless drudgery. 341 00:22:00,393 --> 00:22:03,328 He stood over a cauldron of toxic chemicals 342 00:22:03,362 --> 00:22:05,731 and endlessly stirred. 343 00:22:07,633 --> 00:22:10,435 Joseph had been orphaned at the age of 11 344 00:22:10,469 --> 00:22:14,271 and given to a harsh master named Weichselberger, 345 00:22:14,306 --> 00:22:17,241 the royal mirror-maker. 346 00:22:17,275 --> 00:22:19,543 He prevented Joseph from going to school. 347 00:22:19,578 --> 00:22:22,780 Instead, Joseph labored in 348 00:22:22,815 --> 00:22:24,749 the glass-making workshop by day, 349 00:22:24,783 --> 00:22:27,250 and tended to the master's household chores by night. 350 00:22:32,757 --> 00:22:34,257 Hurry up, stupid! 351 00:22:34,291 --> 00:22:37,227 And remember, no reading. 352 00:22:41,599 --> 00:22:44,433 Until Joseph got his big break. 353 00:22:44,467 --> 00:22:48,560 Weichselberger's house collapsed. 354 00:23:06,619 --> 00:23:08,487 Maximilian, the future king of Bavaria, 355 00:23:08,521 --> 00:23:10,422 hurried to the scene of the calamity 356 00:23:10,456 --> 00:23:11,990 to see if he could help. 357 00:23:12,025 --> 00:23:14,459 Maximilian was known for 358 00:23:14,494 --> 00:23:16,094 taking an interest in his subjects, 359 00:23:16,129 --> 00:23:18,330 which was highly unusual for its time. 360 00:23:32,212 --> 00:23:35,347 In attracting the concern of the future king of Bavaria, 361 00:23:35,381 --> 00:23:36,982 young Joseph Fraunhofer 362 00:23:37,016 --> 00:23:39,818 found an aperture into a different universe. 363 00:23:39,852 --> 00:23:42,287 And not just for himself. 364 00:23:45,091 --> 00:23:46,859 Prince Maximilian gave Joseph money 365 00:23:46,893 --> 00:23:48,694 and asked his privy councilor 366 00:23:48,728 --> 00:23:50,162 to provide further help to the boy, 367 00:23:50,196 --> 00:23:52,564 should it be needed. 368 00:23:57,437 --> 00:24:00,139 Weichselberger continued to exploit him 369 00:24:00,173 --> 00:24:02,474 and prevent him from attending school. 370 00:24:02,509 --> 00:24:04,543 But the prince's councilor intervened, 371 00:24:04,577 --> 00:24:08,080 offering Joseph a position at the Optical Institute. 372 00:24:08,114 --> 00:24:13,252 This small gesture of kindness really paid off. 373 00:24:25,598 --> 00:24:28,434 By the time he was 27, 374 00:24:28,468 --> 00:24:30,703 Joseph Fraunhofer was the world's leading designer 375 00:24:30,737 --> 00:24:32,738 of high-quality lenses, 376 00:24:32,772 --> 00:24:35,441 telescopes and other optical instruments. 377 00:24:35,475 --> 00:24:39,345 His firm was housed here, in the old Benediktbeuren Abbey. 378 00:24:39,379 --> 00:24:41,547 In the early 19th century, 379 00:24:41,581 --> 00:24:44,883 this was top-secret, ultra-high technology. 380 00:24:47,921 --> 00:24:50,122 The Benedictine monks of earlier times 381 00:24:50,156 --> 00:24:52,124 had taken a vow of secrecy. 382 00:24:52,158 --> 00:24:54,126 This local tradition, 383 00:24:54,160 --> 00:24:55,627 and the ability to restrict access 384 00:24:55,662 --> 00:24:57,196 to Fraunhofer's laboratory, 385 00:24:57,230 --> 00:24:59,198 allowed him to maintain control 386 00:24:59,232 --> 00:25:02,301 of trade and state secrets. 387 00:25:07,407 --> 00:25:09,708 Fraunhofer was experimenting with prisms 388 00:25:09,743 --> 00:25:13,145 to find the best types of glass for precision lenses. 389 00:25:13,179 --> 00:25:15,881 How, he wondered, could he get a better look 390 00:25:15,915 --> 00:25:17,916 at the spectrum that a prism produced? 391 00:25:21,087 --> 00:25:24,890 Friedrich, bring me the theodolite, please. 392 00:25:24,924 --> 00:25:27,826 Okay, while Fraunhofer sets up his theodolite-- 393 00:25:27,861 --> 00:25:29,662 it's a kind of telescope-- 394 00:25:29,696 --> 00:25:32,998 I want to show you something in another part of the abbey. 395 00:25:37,637 --> 00:25:41,373 Sound waves are so beautiful to hear. 396 00:25:43,209 --> 00:25:47,913 Imagine how beautiful they'd be to see. 397 00:25:47,947 --> 00:25:51,150 You ever wondered why organ pipes have different lengths? 398 00:25:53,386 --> 00:25:54,620 I press a key... 399 00:25:57,123 --> 00:25:58,524 it sends compressed air 400 00:25:58,558 --> 00:25:59,792 into a particular pipe, 401 00:25:59,826 --> 00:26:01,627 producing sound waves. 402 00:26:01,661 --> 00:26:04,363 If we could slow the sound waves down a few hundred times, 403 00:26:04,397 --> 00:26:06,532 they would look like this. 404 00:26:10,236 --> 00:26:11,870 The length of the pipe 405 00:26:11,905 --> 00:26:13,339 determines the length of the sound wave 406 00:26:13,373 --> 00:26:14,840 that can fit inside it. 407 00:26:14,874 --> 00:26:16,942 A short pipe gives you a short sound wave. 408 00:26:18,978 --> 00:26:21,714 Short sounds waves have high pitch, or frequency. 409 00:26:27,220 --> 00:26:29,888 Let's stop the waves for a better look. 410 00:26:34,260 --> 00:26:36,195 The distance between adjacent waves 411 00:26:36,229 --> 00:26:37,997 is called the wavelength. 412 00:26:38,031 --> 00:26:40,532 A long pipe gives you a long sound wave 413 00:26:40,567 --> 00:26:42,935 with a low pitch, or low frequency. 414 00:27:34,487 --> 00:27:37,389 The medieval manuscript of this music, "Carmina Burana," 415 00:27:37,424 --> 00:27:40,592 was discovered in this very abbey. 416 00:27:43,797 --> 00:27:46,231 Sound waves can't travel through a vacuum. 417 00:27:46,266 --> 00:27:48,133 They need matter to ride on, 418 00:27:48,168 --> 00:27:51,637 like molecules of air, or water, or rock. 419 00:27:51,671 --> 00:27:53,772 But light waves fly solo. 420 00:27:53,807 --> 00:27:55,975 They can move through empty space. 421 00:27:56,009 --> 00:27:57,609 And fast-- 422 00:27:57,644 --> 00:28:00,746 a million times faster than sound waves in air. 423 00:28:00,780 --> 00:28:02,748 And the wavelengths of the light we see 424 00:28:02,782 --> 00:28:05,284 are so much shorter than sound waves. 425 00:28:05,318 --> 00:28:08,153 About 50,000 light waves 426 00:28:08,188 --> 00:28:10,622 would fit right in here. 427 00:28:11,791 --> 00:28:13,325 Oh, yeah. 428 00:28:13,360 --> 00:28:14,793 Fraunhofer. 429 00:28:21,434 --> 00:28:22,768 Just in time. 430 00:28:22,802 --> 00:28:24,436 We didn't miss it. 431 00:28:24,471 --> 00:28:26,638 Just as the wavelength of sound 432 00:28:26,673 --> 00:28:28,640 determines the pitch that we hear, 433 00:28:28,675 --> 00:28:30,142 the wavelength of light 434 00:28:30,176 --> 00:28:32,611 determines the color that we see. 435 00:28:32,645 --> 00:28:35,080 But how does a prism spread out the colors 436 00:28:35,115 --> 00:28:37,616 concealed in a beam of sunlight? 437 00:28:37,650 --> 00:28:41,587 When light travels through air or space, 438 00:28:41,621 --> 00:28:43,989 all its colors move at the same speed. 439 00:28:46,026 --> 00:28:48,794 But when it hits glass at an angle, 440 00:28:48,828 --> 00:28:51,230 the light slows down and changes direction. 441 00:28:52,799 --> 00:28:54,767 Inside the prism, 442 00:28:54,801 --> 00:28:56,802 each color moves at a different speed. 443 00:29:01,141 --> 00:29:02,941 In glass, violet light, 444 00:29:02,976 --> 00:29:05,144 which is carried by the shortest waves we see, 445 00:29:05,178 --> 00:29:07,179 slows down more than red light, 446 00:29:07,213 --> 00:29:09,648 which has the longest waves. 447 00:29:11,484 --> 00:29:13,886 These changes in speed 448 00:29:13,920 --> 00:29:16,455 pry the colors apart, 449 00:29:16,489 --> 00:29:18,290 sending their waves off 450 00:29:18,324 --> 00:29:20,726 in slightly different directions. 451 00:29:21,928 --> 00:29:23,929 That's how a prism works. 452 00:29:26,066 --> 00:29:28,333 If I seem unduly emotional about this, 453 00:29:28,368 --> 00:29:31,170 it's because Joseph Fraunhofer is about to do 454 00:29:31,204 --> 00:29:34,707 what Isaac Newton could've done, but didn't. 455 00:29:34,741 --> 00:29:36,809 And it'll have a powerful effect 456 00:29:36,843 --> 00:29:38,677 on the course of my own life. 457 00:30:01,701 --> 00:30:03,736 You are witnessing the marriage 458 00:30:03,770 --> 00:30:05,371 of physics and astronomy, 459 00:30:05,405 --> 00:30:09,274 the birth of my own field of science, 460 00:30:09,309 --> 00:30:11,744 astrophysics. 461 00:30:13,747 --> 00:30:15,514 Written in the light, 462 00:30:15,548 --> 00:30:18,951 in those vertical black lines... 463 00:30:20,387 --> 00:30:23,355 is secret code. 464 00:30:23,390 --> 00:30:26,191 Fraunhofer looked at them, and wondered... 465 00:30:26,226 --> 00:30:28,227 Why? 466 00:30:30,130 --> 00:30:33,465 A code that comes to us 467 00:30:33,500 --> 00:30:35,934 from an alien universe. 468 00:30:46,299 --> 00:30:47,546 What is the message 469 00:30:47,632 --> 00:30:51,236 written in these dark, vertical lines? 470 00:30:56,309 --> 00:30:58,376 It took a hundred years of thinking, 471 00:30:58,411 --> 00:31:01,713 questioning, searching to decipher it. 472 00:31:21,267 --> 00:31:23,401 Lovely, isn't it? 473 00:31:23,436 --> 00:31:24,970 Why? 474 00:31:25,004 --> 00:31:28,473 There are many layers to the fine structure of beauty... 475 00:31:28,508 --> 00:31:31,643 the chemistry of the Earth and its atmosphere... 476 00:31:31,677 --> 00:31:34,613 the evolution of life... 477 00:31:34,647 --> 00:31:38,216 Many distinct threads. 478 00:31:38,251 --> 00:31:41,319 Let's just examine one, at the surface... 479 00:31:41,354 --> 00:31:43,755 the colors of nature that dazzle us. 480 00:31:43,789 --> 00:31:46,892 What's really happening? 481 00:31:46,926 --> 00:31:48,793 How does the red, the blue... 482 00:31:48,828 --> 00:31:51,796 the astonishing palette of nature's colors... 483 00:31:55,801 --> 00:31:58,436 how do they happen? 484 00:32:01,107 --> 00:32:03,275 Light waves of different lengths from the Sun 485 00:32:03,309 --> 00:32:04,709 strike the Earth. 486 00:32:06,112 --> 00:32:08,146 The petals of these particular flowers 487 00:32:08,181 --> 00:32:09,748 absorb all the low-energy, 488 00:32:09,782 --> 00:32:12,017 long red wavelengths of light. 489 00:32:12,051 --> 00:32:13,752 But the petals reflect 490 00:32:13,786 --> 00:32:17,088 the shorter, high-energy blue wavelengths. 491 00:32:17,123 --> 00:32:19,858 That interaction between starlight and petal-- 492 00:32:19,892 --> 00:32:21,860 or water, or Van Gogh-- 493 00:32:21,894 --> 00:32:23,461 is what makes blue. 494 00:32:23,496 --> 00:32:25,630 The longest waves, 495 00:32:25,665 --> 00:32:27,465 the ones we see as red, 496 00:32:27,500 --> 00:32:30,068 have the lowest energy. 497 00:32:33,005 --> 00:32:35,340 Color is the way our eyes perceive 498 00:32:35,374 --> 00:32:37,242 how energetic light waves are. 499 00:32:39,078 --> 00:32:40,779 A sunset... 500 00:32:40,813 --> 00:32:42,948 a flag... 501 00:32:42,982 --> 00:32:45,383 the eyes of your beloved... 502 00:32:45,418 --> 00:32:47,152 that shiny new car. 503 00:32:47,186 --> 00:32:49,154 The feelings they inspire 504 00:32:49,188 --> 00:32:50,989 happen when something inside you 505 00:32:51,023 --> 00:32:53,492 is triggered by a particular variation 506 00:32:53,526 --> 00:32:56,995 in the frequency and energy of light waves. 507 00:32:58,764 --> 00:32:59,898 And the secret message? 508 00:32:59,932 --> 00:33:01,633 Those black vertical lines 509 00:33:01,667 --> 00:33:03,668 in Fraunhofer's spectrum? 510 00:33:03,703 --> 00:33:05,804 What makes them? 511 00:33:05,838 --> 00:33:08,006 They occur when the light waves 512 00:33:08,040 --> 00:33:10,809 of those particular colors are being absorbed. 513 00:33:10,843 --> 00:33:13,378 It happens on another level of reality, 514 00:33:13,412 --> 00:33:16,414 far smaller than the world we're used to operating in. 515 00:33:16,449 --> 00:33:19,017 To get there, we'll need to become 516 00:33:19,051 --> 00:33:21,786 ten billion times smaller than we are. 517 00:33:24,557 --> 00:33:26,925 We could pick any one of these atoms. 518 00:33:26,959 --> 00:33:30,028 But let's go for the hydrogen atom. 519 00:33:30,062 --> 00:33:32,531 The hydrogen atom is the most plentiful kind 520 00:33:32,565 --> 00:33:34,933 of atom in the cosmos. 521 00:33:34,967 --> 00:33:37,369 And the simplest. 522 00:33:44,877 --> 00:33:48,046 It has only one electron. 523 00:33:48,080 --> 00:33:50,582 And only one proton. 524 00:33:50,616 --> 00:33:52,684 We've entered the quantum realm. 525 00:33:52,718 --> 00:33:54,519 It doesn't correspond 526 00:33:54,554 --> 00:33:57,289 to ordinary human experience. 527 00:33:57,323 --> 00:34:00,525 Common sense is no help here at all. 528 00:34:00,560 --> 00:34:03,562 Take the hydrogen atom's electron, for example. 529 00:34:05,498 --> 00:34:07,732 In an atom, an electron 530 00:34:07,767 --> 00:34:09,467 doesn't exist between orbitals. 531 00:34:09,502 --> 00:34:11,269 It disappears from one orbital 532 00:34:11,304 --> 00:34:13,939 and reappears in another. 533 00:34:13,973 --> 00:34:15,774 It's as if you took an elevator from the second floor 534 00:34:15,808 --> 00:34:19,077 to the fourth floor, but ceased to exist in between. 535 00:34:19,111 --> 00:34:20,812 And another thing. 536 00:34:20,847 --> 00:34:23,782 Quantum elevators only stop at certain floors. 537 00:34:23,816 --> 00:34:27,219 The sizes of the electron orbits are strictly limited, 538 00:34:27,253 --> 00:34:30,088 and different for the atoms of every element. 539 00:34:31,624 --> 00:34:33,959 That's why the elements are different. 540 00:34:33,993 --> 00:34:35,327 The chemistry of anything is determined 541 00:34:35,361 --> 00:34:36,928 by its electron orbits. 542 00:34:36,963 --> 00:34:39,831 The force that holds an electron in orbit 543 00:34:39,866 --> 00:34:41,666 has nothing to do with gravity. 544 00:34:41,701 --> 00:34:45,237 It's a force of electrical attraction. 545 00:34:45,271 --> 00:34:47,572 The electron dances a wavy ring 546 00:34:47,607 --> 00:34:49,841 around the central nucleus of a hydrogen atom. 547 00:34:49,876 --> 00:34:52,644 And makes quantum leaps from orbit to orbit. 548 00:34:52,678 --> 00:34:53,945 Up or down. 549 00:34:53,980 --> 00:34:55,347 The larger the orbit, 550 00:34:55,381 --> 00:34:57,415 the greater the energy of an electron. 551 00:34:57,450 --> 00:34:59,818 An electron has 552 00:34:59,852 --> 00:35:01,987 to get energy to leap to a larger orbit. 553 00:35:02,021 --> 00:35:04,823 And it has to lose energy to jump back down. 554 00:35:04,857 --> 00:35:08,159 Every upward leap is caused by... 555 00:35:08,194 --> 00:35:11,596 an atom absorbing a light wave. 556 00:35:11,631 --> 00:35:15,433 But we have no idea what causes the downward leaps. 557 00:35:15,468 --> 00:35:19,037 What we do know that such leaps always produce a light wave 558 00:35:19,071 --> 00:35:21,706 whose color matches the energy difference 559 00:35:21,741 --> 00:35:23,508 between the orbitals. 560 00:35:28,414 --> 00:35:32,817 The Sun's surface radiates light waves of all colors. 561 00:35:32,852 --> 00:35:34,653 If you look at sunlight through a prism, 562 00:35:34,687 --> 00:35:36,688 you'll see its spectrum. 563 00:35:39,325 --> 00:35:42,160 When you magnify the spectrum with a telescope, 564 00:35:42,195 --> 00:35:44,062 as Joseph Fraunhofer did, 565 00:35:44,096 --> 00:35:45,664 you raise the curtain 566 00:35:45,698 --> 00:35:48,900 on the electron dance within the atom. 567 00:35:48,935 --> 00:35:51,136 When the energy of the electron flags, 568 00:35:51,170 --> 00:35:52,837 and it drops to a lower orbital, 569 00:35:52,872 --> 00:35:55,240 the light wave it emits scatters. 570 00:35:55,274 --> 00:35:57,676 Most of it doesn't reach us. 571 00:35:57,710 --> 00:35:59,244 That leaves a dark gap 572 00:35:59,278 --> 00:36:02,180 or black vertical line in the spectrum. 573 00:36:02,215 --> 00:36:04,749 These dark lines are the shadows 574 00:36:04,784 --> 00:36:06,384 cast by hydrogen atoms 575 00:36:06,419 --> 00:36:08,353 in the atmosphere of the Sun. 576 00:36:08,387 --> 00:36:11,089 Sodium atoms cast different shadows. 577 00:36:11,123 --> 00:36:14,192 Their electrons dance to a different tune. 578 00:36:14,227 --> 00:36:16,094 A grain of table salt is composed 579 00:36:16,128 --> 00:36:17,929 of sodium and chlorine atoms. 580 00:36:17,964 --> 00:36:20,398 Ten million billion of them 581 00:36:20,433 --> 00:36:22,400 doing their crazy dances 582 00:36:22,435 --> 00:36:25,270 in a single grain of salt. 583 00:36:25,304 --> 00:36:28,206 And a single iron atom with 26 electrons 584 00:36:28,241 --> 00:36:30,575 is like a great big production number 585 00:36:30,610 --> 00:36:33,912 in a Broadway musical. 586 00:36:36,315 --> 00:36:40,218 When you look at a star with a spectroscope, 587 00:36:40,253 --> 00:36:42,687 you see the dark lines from all the elements 588 00:36:42,722 --> 00:36:44,356 in its atmosphere. 589 00:36:44,390 --> 00:36:46,258 Show me the spectrum of anything, 590 00:36:46,292 --> 00:36:49,060 whether here on Earth or from a distant star, 591 00:36:49,095 --> 00:36:52,130 and I'll tell you what it's made of. 592 00:36:52,164 --> 00:36:55,767 Fraunhofer's lines are the atomic signatures 593 00:36:55,801 --> 00:36:59,771 of the elements writ large across the cosmos. 594 00:36:59,805 --> 00:37:01,873 As with every other major revelation 595 00:37:01,908 --> 00:37:04,409 in the history of science, it opened the way 596 00:37:04,443 --> 00:37:07,412 to newer and deeper mysteries. 597 00:37:07,446 --> 00:37:10,415 And to the revelation that there were 598 00:37:10,449 --> 00:37:13,485 many more secrets hiding in the light. 599 00:37:21,433 --> 00:37:24,369 When Joseph Fraunhofer combined a prism with a telescope 600 00:37:24,371 --> 00:37:26,638 and turned it toward the skies, 601 00:37:26,640 --> 00:37:30,141 he brought the stars much closer to us. 602 00:37:41,120 --> 00:37:43,855 When he was only 39, 603 00:37:43,857 --> 00:37:46,024 he contracted a fatal illness. 604 00:37:46,026 --> 00:37:48,693 Perhaps as a result of his early and long-term exposure 605 00:37:48,695 --> 00:37:51,629 to the toxic chemicals of glassmaking. 606 00:37:51,631 --> 00:37:55,633 You never know where the next genius will come from. 607 00:37:59,572 --> 00:38:04,075 How many of them do we leave in the rubble? 608 00:38:04,077 --> 00:38:07,345 The prince and his kingdom were immeasurably enriched 609 00:38:07,347 --> 00:38:10,715 by that act of kindness to a poor orphan. 610 00:38:10,717 --> 00:38:13,151 Fraunhofer's discoveries transformed Bavaria 611 00:38:13,153 --> 00:38:17,422 from a rural backwater to a technological powerhouse. 612 00:38:19,258 --> 00:38:21,693 As he lay dying, the government was desperate 613 00:38:21,695 --> 00:38:24,596 to preserve every shred of his precious knowledge 614 00:38:24,598 --> 00:38:26,898 about the high technology of optical glass. 615 00:38:29,935 --> 00:38:31,870 But it could only be divulged to a person 616 00:38:31,872 --> 00:38:34,072 with top security clearance-- 617 00:38:34,074 --> 00:38:35,840 the director of the mint. 618 00:38:52,925 --> 00:38:55,526 The government kept Fraunhofer's technology 619 00:38:55,528 --> 00:38:57,428 for making perfect optical glass 620 00:38:57,430 --> 00:39:00,698 a State secret for another hundred years. 621 00:39:00,700 --> 00:39:02,700 This would prove to be a major obstacle 622 00:39:02,735 --> 00:39:05,203 for someone we'll meet later in our journey. 623 00:39:05,237 --> 00:39:07,772 But Fraunhofer would allow no such secrecy 624 00:39:07,806 --> 00:39:10,375 where his pure scientific research was concerned. 625 00:39:10,409 --> 00:39:14,012 He knew that science requires openness to flourish; 626 00:39:14,046 --> 00:39:18,082 that our understanding of nature belongs to the world. 627 00:39:18,117 --> 00:39:21,019 As soon as Fraunhofer discovered the spectral lines, 628 00:39:21,053 --> 00:39:23,588 he published everything he knew about them. 629 00:39:23,622 --> 00:39:26,424 And the reverberations of his momentous discovery 630 00:39:26,458 --> 00:39:29,227 echo still. 631 00:39:32,398 --> 00:39:36,367 His spectral lines revealed that the visible cosmos 632 00:39:36,402 --> 00:39:39,671 is all made of the same elements. 633 00:39:42,708 --> 00:39:45,176 The planets... 634 00:39:53,318 --> 00:39:55,787 The stars... 635 00:40:00,159 --> 00:40:02,293 The galaxies... 636 00:40:06,532 --> 00:40:09,534 We, ourselves, and all of life... 637 00:40:16,208 --> 00:40:19,744 The same star stuff. 638 00:40:25,184 --> 00:40:26,851 He made it possible for us to know 639 00:40:26,885 --> 00:40:29,353 what's in the atmosphere of other worlds. 640 00:40:31,824 --> 00:40:35,460 And in galaxies millions of light-years away. 641 00:40:35,494 --> 00:40:37,495 Spectral lines revealed not only the composition 642 00:40:37,529 --> 00:40:39,997 of far-off objects, but also their motion 643 00:40:40,032 --> 00:40:42,200 towards or away from us. 644 00:40:42,234 --> 00:40:45,303 Using them, we discovered that our universe is expanding. 645 00:40:45,337 --> 00:40:48,906 But perhaps the greatest revelation of spectroscopy 646 00:40:48,941 --> 00:40:51,742 is the discovery of the thing it cannot see. 647 00:40:57,750 --> 00:40:59,917 A hidden universe of dark matter 648 00:40:59,952 --> 00:41:03,187 six times more massive than the familiar cosmos. 649 00:41:03,222 --> 00:41:05,389 It's made of some mysterious substance 650 00:41:05,424 --> 00:41:09,994 that does not emit, reflect or absorb any kind of light. 651 00:41:10,028 --> 00:41:12,497 We only know it's there because of its gravity, 652 00:41:12,531 --> 00:41:14,599 which pulls on all the galaxies 653 00:41:14,633 --> 00:41:17,368 and speeds up the visible stars within them. 654 00:41:21,373 --> 00:41:24,842 There are many more kinds of light than our eyes can see. 655 00:41:24,877 --> 00:41:28,279 Confining our perception of nature to visible light 656 00:41:28,313 --> 00:41:30,615 is like listening to music 657 00:41:30,649 --> 00:41:32,216 in only one octave. 658 00:41:34,787 --> 00:41:36,788 There are so many more. 659 00:41:36,822 --> 00:41:38,756 They differ only in wavelength, 660 00:41:38,791 --> 00:41:40,892 but over a huge range. 661 00:41:40,926 --> 00:41:43,494 For instance, infrared light... 662 00:41:48,834 --> 00:41:51,969 the kind that William Herschel discovered 663 00:41:52,004 --> 00:41:53,771 Or X-ray light. 664 00:41:58,844 --> 00:42:00,912 Or radio light. 665 00:42:05,651 --> 00:42:07,485 Or in gamma-ray light. 666 00:42:13,292 --> 00:42:16,561 These are not just different ways of seeing the same thing. 667 00:42:16,595 --> 00:42:18,162 These other kinds of light 668 00:42:18,197 --> 00:42:21,799 reveal different objects and phenomena in the cosmos. 669 00:42:21,834 --> 00:42:25,002 In gamma-ray light, for example, we can see mysterious explosions 670 00:42:25,037 --> 00:42:26,771 in distant galaxies 671 00:42:26,805 --> 00:42:29,106 that we would otherwise miss. 672 00:42:32,044 --> 00:42:34,912 And in microwave light, we can see all the way back 673 00:42:34,947 --> 00:42:37,348 to the birth of the universe. 674 00:42:39,885 --> 00:42:43,187 We have only just opened our eyes.