1 00:00:02,268 --> 00:00:05,842 We live on one level of existence, but there are others. 2 00:00:06,866 --> 00:00:10,543 These hidden dimensions of reality are everywhere. 3 00:00:10,551 --> 00:00:13,044 Far away, across the light years. 4 00:00:13,104 --> 00:00:14,343 Beneath our feet. 5 00:00:14,345 --> 00:00:17,646 And even inside you and me. 6 00:00:17,987 --> 00:00:20,447 We are made of atoms. 7 00:00:22,379 --> 00:00:24,148 There are more atoms in your eye, 8 00:00:24,283 --> 00:00:27,683 than there are stars and all the galaxies of the known universe. 9 00:00:32,449 --> 00:00:34,584 The same is true of any solid object 10 00:00:34,618 --> 00:00:37,320 larger than the tip of your little finger. 11 00:00:37,354 --> 00:00:41,190 I'm a collection of three billion, billion, billion 12 00:00:41,225 --> 00:00:44,126 intricately arranged atoms called Neil Degrasse Tyson. 13 00:00:44,161 --> 00:00:48,998 You are a similar collection with a different name. 14 00:00:49,032 --> 00:00:50,533 We don't usually think of ourselves this way 15 00:00:50,567 --> 00:00:54,604 because that level of reality lies beyond the realm of our senses. 16 00:00:54,638 --> 00:00:56,839 But we're not gonna let that stop us. 17 00:00:56,874 --> 00:01:00,042 We can go deeper into the wonder. 18 00:02:44,670 --> 00:02:47,171 Atoms let matter do funny things. 19 00:02:47,206 --> 00:02:50,141 To understand water, you need to know what its atoms are doing. 20 00:02:50,175 --> 00:02:52,677 Every molecule of water is composed 21 00:02:52,711 --> 00:02:54,245 of two tiny hydrogen atoms 22 00:02:54,280 --> 00:02:56,915 attached to a larger oxygen atom. 23 00:02:56,949 --> 00:02:59,017 That's why we call it H20. 24 00:02:59,051 --> 00:03:02,153 If it's not too hot or too cold, 25 00:03:02,188 --> 00:03:04,856 the molecules can slide and tumble past each other. 26 00:03:04,890 --> 00:03:07,158 There's still some stickiness between the molecules, 27 00:03:07,192 --> 00:03:10,428 but not enough to lock them into a rigid solid. 28 00:03:10,462 --> 00:03:13,198 That's what makes something a liquid. 29 00:03:13,232 --> 00:03:14,866 The sun warms the water. 30 00:03:14,900 --> 00:03:16,267 And with more energy, 31 00:03:16,302 --> 00:03:18,203 the molecules move faster. 32 00:03:18,237 --> 00:03:20,004 That's all that temperature is. 33 00:03:20,039 --> 00:03:22,006 Those molecules are moving fast enough 34 00:03:22,041 --> 00:03:25,176 to break the weak bonds that hold them to their neighbors. 35 00:03:25,211 --> 00:03:27,078 That's evaporation. 36 00:03:27,112 --> 00:03:29,013 The air we breathe is made of 37 00:03:29,048 --> 00:03:31,049 nitrogen and oxygen molecules 38 00:03:31,083 --> 00:03:34,852 with a scattering of water vapor and carbon dioxide. 39 00:03:34,887 --> 00:03:36,854 Incoming! 40 00:03:36,889 --> 00:03:39,123 That's condensation. 41 00:03:39,158 --> 00:03:41,726 A dewdrop is the momentary triumph 42 00:03:41,760 --> 00:03:43,862 of condensation over evaporation. 43 00:03:43,896 --> 00:03:45,630 And while it lasts, 44 00:03:45,664 --> 00:03:49,100 it's a little cosmos with its own worlds... 45 00:03:49,134 --> 00:03:52,403 creatures, drama. 46 00:03:52,438 --> 00:03:54,639 To explore the far-flung realms 47 00:03:54,673 --> 00:03:55,907 of this dewdrop, 48 00:03:55,941 --> 00:03:57,308 we're gonna need a ship. 49 00:03:58,611 --> 00:04:00,545 One with twin engines... 50 00:04:00,579 --> 00:04:02,947 science and imagination. 51 00:04:08,921 --> 00:04:10,822 That's a single-celled paramecium, 52 00:04:10,856 --> 00:04:13,625 one of a multitude of skilled hunter-warriors 53 00:04:13,659 --> 00:04:16,261 that roam the dewdrop. 54 00:04:16,295 --> 00:04:18,830 But they, too, are hunted. 55 00:04:20,666 --> 00:04:23,434 The Dileptus. The paramecium's mortal enemy. 56 00:04:23,469 --> 00:04:27,238 The paramecium might get lucky and score a direct hit. 57 00:04:27,273 --> 00:04:28,940 Even if it doesn't, 58 00:04:28,974 --> 00:04:31,509 the recoil from the barrage will put some distance 59 00:04:31,544 --> 00:04:33,378 between the paramecium and its attacker. 60 00:04:36,148 --> 00:04:38,416 What can I say? 61 00:04:38,450 --> 00:04:40,218 That's life in the dewdrop. 62 00:04:52,298 --> 00:04:54,799 That little guy is tardigrade, 63 00:04:54,834 --> 00:04:58,236 an animal smaller than the head of a pin. 64 00:05:00,639 --> 00:05:02,640 Don't underestimate them. 65 00:05:02,675 --> 00:05:04,642 Tardigrades have been living on this planet 66 00:05:04,677 --> 00:05:05,944 a lot longer than we have. 67 00:05:05,978 --> 00:05:08,746 About 500 million years. 68 00:05:11,217 --> 00:05:13,218 For every one of us, 69 00:05:13,252 --> 00:05:16,421 there's at least a billion of them. 70 00:05:19,491 --> 00:05:21,793 They can make a living anywhere on earth. 71 00:05:21,827 --> 00:05:25,463 In the frigid peaks of the tallest mountains, 72 00:05:25,498 --> 00:05:27,332 in the cauldrons of erupting volcanoes, 73 00:05:27,366 --> 00:05:29,868 and in the deep ocean vents at the bottom of the sea. 74 00:05:29,902 --> 00:05:31,302 Tardigrades are so tough, 75 00:05:31,337 --> 00:05:32,637 they can survive naked 76 00:05:32,671 --> 00:05:34,739 in the vacuum of space. 77 00:05:34,773 --> 00:05:37,075 They've survived all five 78 00:05:37,109 --> 00:05:39,410 of the most recent mass extinctions on this planet. 79 00:05:39,445 --> 00:05:42,714 A visitor from another world could be forgiven 80 00:05:42,748 --> 00:05:46,117 for thinking of earth as the planet of the tardigrades. 81 00:05:49,889 --> 00:05:51,489 If we're ever gonna get to the bottom of this dewdrop, 82 00:05:51,524 --> 00:05:53,858 better get a move on. 83 00:05:56,362 --> 00:05:59,497 Every leaf and tiny clump of moss 84 00:05:59,532 --> 00:06:01,499 has hundreds of thousands 85 00:06:01,534 --> 00:06:04,002 of microscopic mouths called Stomata. 86 00:06:04,036 --> 00:06:06,004 Plants breathe through them, 87 00:06:06,038 --> 00:06:07,505 taking in carbon dioxide 88 00:06:07,540 --> 00:06:10,375 and exhaling the oxygen that we need to live. 89 00:06:10,409 --> 00:06:12,710 The plants can survive without us. 90 00:06:12,745 --> 00:06:14,946 But we and all the other animals... 91 00:06:14,980 --> 00:06:18,116 we'd be toast without them. 92 00:06:18,150 --> 00:06:20,351 The plants make food out of sunlight. 93 00:06:20,386 --> 00:06:22,754 We animals can't do that. 94 00:06:22,788 --> 00:06:24,722 To see how they do it, 95 00:06:24,757 --> 00:06:26,257 we have to go deeper, 96 00:06:26,292 --> 00:06:28,359 make ourselves about a thousand times smaller 97 00:06:28,394 --> 00:06:31,129 to get into their treasure house, 98 00:06:31,163 --> 00:06:32,897 the place where they keep the good stuff... 99 00:06:32,932 --> 00:06:34,799 the chlorophyll. 100 00:06:34,834 --> 00:06:36,267 That's the molecule 101 00:06:36,302 --> 00:06:39,404 that converts sunlight into energy. 102 00:06:42,308 --> 00:06:44,475 Every one of those rectangles is a plant cell. 103 00:06:44,510 --> 00:06:46,478 And those tiny green vehicles 104 00:06:46,512 --> 00:06:49,380 are its energy factories. 105 00:06:49,415 --> 00:06:50,982 If we could steal their trade secrets, 106 00:06:51,016 --> 00:06:53,551 it would trigger a new industrial revolution. 107 00:06:53,586 --> 00:06:55,386 But to spy on them, 108 00:06:55,421 --> 00:06:57,355 we're gonna need to go deeper still. 109 00:07:08,839 --> 00:07:11,474 What alien world has the ship of the imagination 110 00:07:11,509 --> 00:07:13,743 carried us to this time? 111 00:07:13,778 --> 00:07:15,979 It's the cosmos... 112 00:07:16,013 --> 00:07:19,649 Contained within a dewdrop. 113 00:07:19,684 --> 00:07:22,619 We're on an industrial espionage mission. 114 00:07:22,653 --> 00:07:25,088 If we can penetrate the trade secrets 115 00:07:25,122 --> 00:07:27,991 of the manufacturing process in that chloroplast, 116 00:07:28,025 --> 00:07:30,827 let's just say our whole future hangs in the balance. 117 00:07:30,861 --> 00:07:34,097 This chloroplast is using sunlight 118 00:07:34,131 --> 00:07:35,799 to break water molecules 119 00:07:35,833 --> 00:07:38,301 into atoms of hydrogen and oxygen. 120 00:07:38,335 --> 00:07:40,603 It combines the hydrogen with carbon dioxide 121 00:07:40,638 --> 00:07:42,305 to make sugar, 122 00:07:42,340 --> 00:07:45,642 and releases the oxygen as a waste product. 123 00:07:45,676 --> 00:07:48,511 To see how it happens, we have to go even deeper, 124 00:07:48,546 --> 00:07:50,146 get even smaller. 125 00:07:50,181 --> 00:07:53,416 We're talking atomic scale. 126 00:07:53,451 --> 00:07:55,085 Bingo. 127 00:07:55,119 --> 00:07:57,020 This assembly line is the heart 128 00:07:57,054 --> 00:07:58,755 of the molecular industrial complex. 129 00:07:58,789 --> 00:08:00,757 At the molecular level, 130 00:08:00,791 --> 00:08:02,792 things happen too fast for us to see. 131 00:08:02,827 --> 00:08:05,195 So we'll have to slow them down 132 00:08:05,229 --> 00:08:07,464 about a billion times. 133 00:08:10,568 --> 00:08:12,369 Those larger molecules are carbon dioxide. 134 00:08:12,403 --> 00:08:13,870 Each one of them is made 135 00:08:13,904 --> 00:08:15,772 of one carbon and two oxygen atoms. 136 00:08:15,806 --> 00:08:18,975 When sunlight strikes a green molecule of chlorophyll, 137 00:08:19,010 --> 00:08:22,145 it sets in motion a series of chemical reactions, 138 00:08:22,179 --> 00:08:23,980 breaking apart water molecules 139 00:08:24,015 --> 00:08:26,816 and freeing energetic electrons. 140 00:08:29,053 --> 00:08:30,687 And that's just the day shift, 141 00:08:30,721 --> 00:08:33,556 when sunlight supplies the incoming stream of energy. 142 00:08:33,591 --> 00:08:36,526 There's a second shift that works day and night 143 00:08:36,560 --> 00:08:39,396 using the solar energy kept in reserve. 144 00:08:41,065 --> 00:08:43,633 The energy of the free electrons is put to work, 145 00:08:43,668 --> 00:08:47,837 combining carbon dioxide with hydrogen from the water. 146 00:08:47,872 --> 00:08:52,542 The end product is sugar, which stores the solar energy. 147 00:08:52,576 --> 00:08:55,512 The chloroplast is a three-billion-year-old 148 00:08:55,546 --> 00:08:58,048 solar energy collector. 149 00:08:58,082 --> 00:09:00,817 This sub-microscopic solar battery 150 00:09:00,851 --> 00:09:03,353 is what drives all the forests and the fields 151 00:09:03,387 --> 00:09:05,588 and the plankton of the seas. 152 00:09:05,623 --> 00:09:07,323 And the animals. 153 00:09:07,358 --> 00:09:09,392 Including us. 154 00:09:09,427 --> 00:09:11,728 The solar-powered biosphere 155 00:09:11,762 --> 00:09:15,065 collects and processes six times more power 156 00:09:15,099 --> 00:09:17,267 than our entire civilization. 157 00:09:17,301 --> 00:09:19,202 We understand on a chemical level 158 00:09:19,236 --> 00:09:20,904 how photosynthesis works. 159 00:09:20,938 --> 00:09:23,039 We can recreate the process in a laboratory. 160 00:09:23,074 --> 00:09:25,842 But we're not as good at it as plants are. 161 00:09:25,876 --> 00:09:27,911 And it's not surprising, 162 00:09:27,945 --> 00:09:30,347 considering nature has been at this for billions of years, 163 00:09:30,381 --> 00:09:32,449 and we've only just started. 164 00:09:32,483 --> 00:09:34,017 But if we could figure out 165 00:09:34,051 --> 00:09:36,286 the trade secrets of photosynthesis, 166 00:09:36,320 --> 00:09:38,555 every of other source of energy 167 00:09:38,589 --> 00:09:40,223 we depend on today... 168 00:09:40,257 --> 00:09:42,859 coal, oil, natural gas... 169 00:09:42,893 --> 00:09:45,295 would become obsolete. 170 00:09:45,329 --> 00:09:47,964 Photosynthesis is the ultimate green power. 171 00:09:47,999 --> 00:09:49,866 It doesn't pollute the air 172 00:09:49,900 --> 00:09:52,268 and is, in fact, carbon neutral. 173 00:09:52,303 --> 00:09:55,238 Artificial photosynthesis on a big enough scale 174 00:09:55,272 --> 00:09:57,273 could reduce the greenhouse effect 175 00:09:57,308 --> 00:10:00,443 that's driving climate change in a dangerous direction. 176 00:10:00,478 --> 00:10:02,979 Uh-oh, place is evaporating. 177 00:10:03,014 --> 00:10:04,447 Time to get out of here. 178 00:10:07,084 --> 00:10:09,552 How fleeting is the life of a dewdrop. 179 00:10:09,587 --> 00:10:12,756 It condenses from thin air in the cool of the night, 180 00:10:12,790 --> 00:10:14,924 only to vanish with the heat of the day. 181 00:10:14,959 --> 00:10:17,827 And what of its inhabitants, the tardigrades? 182 00:10:17,862 --> 00:10:19,562 They'll be fine. 183 00:10:19,597 --> 00:10:21,998 They can go without water for years. 184 00:10:23,100 --> 00:10:24,968 It's hard to imagine, 185 00:10:25,002 --> 00:10:26,636 but plants covered the surface of the earth 186 00:10:26,671 --> 00:10:29,439 for hundreds of millions of years 187 00:10:29,473 --> 00:10:32,909 before they put forth their first flower. 188 00:10:32,943 --> 00:10:35,812 That was about a hundred million years ago, 189 00:10:35,846 --> 00:10:38,481 shortly before the dinosaurs were wiped out. 190 00:10:38,516 --> 00:10:42,652 Our world must've been a relatively drab-looking place back then, 191 00:10:42,687 --> 00:10:45,922 dominated by shades of green and brown. 192 00:10:45,956 --> 00:10:50,260 Yeah, there were giant trees and ferns and other plant life, 193 00:10:50,294 --> 00:10:52,529 but not the purple of an iris 194 00:10:52,563 --> 00:10:55,699 or the crimson of a red, red rose. 195 00:11:02,073 --> 00:11:05,108 Orchids were among the first flowering species 196 00:11:05,142 --> 00:11:09,012 to appear on earth, and they're the most diverse. 197 00:11:10,748 --> 00:11:13,984 Darwin was particularly fascinated 198 00:11:14,018 --> 00:11:15,852 by the comet orchid of Madagascar, 199 00:11:15,886 --> 00:11:19,456 a flower whose pollen is hidden at the bottom 200 00:11:19,490 --> 00:11:23,827 of a very long, thin spur. 201 00:11:23,861 --> 00:11:26,696 There can be no stronger test of an idea 202 00:11:26,731 --> 00:11:28,732 than its predictive power. 203 00:11:28,766 --> 00:11:30,467 On the basis of his theory of evolution 204 00:11:30,501 --> 00:11:31,901 through natural selection, 205 00:11:31,936 --> 00:11:34,571 Darwin speculated that somewhere 206 00:11:34,605 --> 00:11:38,375 on the island of Madagascar, there must live flying insects 207 00:11:38,409 --> 00:11:41,511 with extraordinarily lengthy tongues, 208 00:11:41,545 --> 00:11:43,380 ones long enough to reach the pollen. 209 00:11:43,414 --> 00:11:46,983 No one had ever seen such a beast there, 210 00:11:47,018 --> 00:11:48,718 but Darwin insisted 211 00:11:48,753 --> 00:11:52,055 that an animal fitting this description must exist. 212 00:11:52,089 --> 00:11:53,823 Few people at the time believed him. 213 00:11:53,858 --> 00:11:57,360 It wasn't until more than 50 years later 214 00:11:57,395 --> 00:11:59,696 that Darwin was proven right. 215 00:11:59,730 --> 00:12:05,268 In 1903, a huge hawk moth, called the Morgan's sphinx 216 00:12:05,303 --> 00:12:06,903 was discovered in Madagascar. 217 00:12:06,937 --> 00:12:10,440 Attracted by the Comet Orchid's scent, 218 00:12:10,474 --> 00:12:14,778 the moth slurps its pollen with its foot-long tongue, 219 00:12:14,812 --> 00:12:17,280 exactly as Darwin expected it would. 220 00:12:21,986 --> 00:12:25,255 It's even more amazing that the Morgan's sphinx was discovered 221 00:12:25,289 --> 00:12:27,691 when you consider that more than 90% 222 00:12:27,725 --> 00:12:31,127 of Madagascar's rain forest had been destroyed. 223 00:12:31,162 --> 00:12:33,897 In the years since Darwin's famous prediction, 224 00:12:33,931 --> 00:12:37,100 this moth species could have easily become extinct 225 00:12:37,134 --> 00:12:39,903 with all the others... 226 00:12:39,937 --> 00:12:43,139 every one of them a unique phrase of life's poetry, 227 00:12:43,174 --> 00:12:47,177 written in the atoms by eons of evolution. 228 00:12:52,817 --> 00:12:54,985 Ah, the fragrance of lilacs. 229 00:12:55,019 --> 00:12:56,753 It's one of those scents 230 00:12:56,787 --> 00:12:59,823 that triggers a whole constellation of associations, 231 00:12:59,857 --> 00:13:02,959 all those junes of long ago. 232 00:13:02,994 --> 00:13:04,761 But how does that happen? 233 00:13:04,795 --> 00:13:08,164 How does a smell prompt a movie to start running in your head? 234 00:13:08,199 --> 00:13:10,166 It's not something we can see. 235 00:13:10,201 --> 00:13:12,469 Could it be a wave of energy, like light? 236 00:13:12,503 --> 00:13:15,939 Or is it some kind of microscopic particle? 237 00:13:15,973 --> 00:13:17,641 It's actually a molecule. 238 00:13:17,675 --> 00:13:21,444 Every odor we can sense, whether it comes from burnt toast, 239 00:13:21,479 --> 00:13:24,948 gasoline, or a field of lilacs, 240 00:13:24,982 --> 00:13:27,183 is a cloud of molecules. 241 00:13:27,218 --> 00:13:31,021 These molecules have particular shapes. 242 00:13:31,023 --> 00:13:32,989 When I inhale them, 243 00:13:32,991 --> 00:13:36,993 they stimulate a particular set of receptor cells in my nose. 244 00:13:36,995 --> 00:13:41,231 An electrical signal then travels to my brain, 245 00:13:41,233 --> 00:13:43,900 which identifies the scent as lilac. 246 00:13:47,204 --> 00:13:49,339 Other scents are carried by different molecules 247 00:13:49,341 --> 00:13:52,008 with different shapes. 248 00:13:52,010 --> 00:13:55,312 But when I smell a flower or the smoke from a campfire 249 00:13:55,314 --> 00:13:57,047 or the grease from a motor gear, 250 00:13:57,049 --> 00:14:00,150 I'm often flooded with memories. 251 00:14:00,152 --> 00:14:04,621 Why is it that a simple thing such as the scent of a flower 252 00:14:04,623 --> 00:14:07,490 can trigger powerful memories? 253 00:14:10,528 --> 00:14:14,030 It has to do with the way our brains have evolved. 254 00:14:14,032 --> 00:14:16,399 Our sense of smell kicks in 255 00:14:16,401 --> 00:14:19,002 when the olfactory nerve in our brain is stimulated. 256 00:14:20,771 --> 00:14:24,140 That nerve is located very close to the amygdala, 257 00:14:24,142 --> 00:14:29,079 a structure that is integral to our experience of emotion. 258 00:14:29,081 --> 00:14:32,349 It's also very close to the Hippocampus, 259 00:14:32,351 --> 00:14:34,117 which helps us form memories. 260 00:14:36,954 --> 00:14:40,290 The network of neurons that carry the scent signal 261 00:14:40,292 --> 00:14:43,126 from my nose to my brain has been fine-tuned 262 00:14:43,128 --> 00:14:46,196 over hundreds of millions of years of evolution. 263 00:14:48,299 --> 00:14:50,600 It's a survival mechanism that can alert us 264 00:14:50,602 --> 00:14:53,470 to danger or guide us to safety. 265 00:14:56,040 --> 00:14:58,074 If you you can detect the predator 266 00:14:58,076 --> 00:15:01,111 before he's near enough to strike, 267 00:15:01,113 --> 00:15:03,446 or the fire before it traps you in the forest, 268 00:15:03,448 --> 00:15:05,615 you have a much better chance to survive 269 00:15:05,617 --> 00:15:08,451 and pass on your genes to the next generation. 270 00:15:14,225 --> 00:15:16,793 That lovely scent from this field of flowers 271 00:15:16,795 --> 00:15:19,829 sets off a unique combination of nerve signals. 272 00:15:19,831 --> 00:15:23,433 Only that exact combination can crack the safe 273 00:15:23,435 --> 00:15:27,170 where the memory of lilacs is stored inside my brain. 274 00:15:31,909 --> 00:15:33,443 Wonder who they're for. 275 00:15:34,912 --> 00:15:36,980 Maybe we'll find out later. 276 00:15:36,982 --> 00:15:40,917 But first, there's another hidden cosmos waiting for us. 277 00:16:01,151 --> 00:16:03,547 The plants are softly breathing, 278 00:16:03,582 --> 00:16:06,450 inhaling molecules of carbon dioxide 279 00:16:06,485 --> 00:16:09,186 and exhaling molecules of oxygen. 280 00:16:09,221 --> 00:16:10,688 And I'm doing the opposite. 281 00:16:10,722 --> 00:16:14,058 Unlike snowflakes and fingerprints, 282 00:16:14,092 --> 00:16:15,860 atoms or molecules of the same kind 283 00:16:15,894 --> 00:16:18,996 are utterly identical to one another. 284 00:16:19,031 --> 00:16:20,698 With every breath we take, 285 00:16:20,732 --> 00:16:23,901 we inhale as many molecules as there are stars 286 00:16:23,936 --> 00:16:26,470 in all the galaxies in the visible universe. 287 00:16:26,505 --> 00:16:29,540 And every breath we exhale is circulated through the air, 288 00:16:29,574 --> 00:16:32,076 and mixed gradually across the continents, 289 00:16:32,110 --> 00:16:36,047 it becomes available for others to breathe. 290 00:16:36,081 --> 00:16:37,415 Breathe with me. 291 00:16:48,227 --> 00:16:51,729 We all just inhaled about 100 million molecules 292 00:16:51,763 --> 00:16:53,931 that once passed through the lungs of everyone 293 00:16:53,966 --> 00:16:56,000 who ever lived before us. 294 00:16:56,034 --> 00:16:59,203 Think of it... This kind of atomic reincarnation 295 00:16:59,238 --> 00:17:01,505 is another link to our distant ancestors, 296 00:17:01,540 --> 00:17:05,042 including those who first launched us on our explorations 297 00:17:05,077 --> 00:17:07,211 of the unseen universes. 298 00:17:07,246 --> 00:17:10,681 These universes are as real as you or me, 299 00:17:10,716 --> 00:17:12,917 and they surround us. 300 00:17:17,422 --> 00:17:19,790 There was a moment when we awakened 301 00:17:19,825 --> 00:17:22,426 to a new way of thinking and seeing. 302 00:17:22,461 --> 00:17:25,897 It happened about 2,500 years ago 303 00:17:25,931 --> 00:17:27,732 on the Greek islands that lie 304 00:17:27,766 --> 00:17:31,035 between the empires of the east and west. 305 00:17:31,069 --> 00:17:35,139 There, merchants, tourists and sailors freely mingled, 306 00:17:35,173 --> 00:17:38,276 exchanging tales of great kings and gods. 307 00:17:38,310 --> 00:17:42,780 In Ionian cities and towns like Miletus, in what is now Turkey, 308 00:17:42,814 --> 00:17:44,982 the most fundamental elements 309 00:17:45,017 --> 00:17:47,919 of the way we live now first appeared. 310 00:17:51,356 --> 00:17:55,626 Here, for the first time, reenactments of aspects of life 311 00:17:55,661 --> 00:17:58,596 created and executed by professionals 312 00:17:58,630 --> 00:18:01,432 with the expectation of touching something deep 313 00:18:01,466 --> 00:18:03,234 within the hearts of the audience, 314 00:18:03,268 --> 00:18:06,137 or just making them laugh... 315 00:18:06,171 --> 00:18:10,381 The first plays, dramas and comedies, were performed. 316 00:18:10,383 --> 00:18:13,800 Here also was born a radical new idea... 317 00:18:13,802 --> 00:18:15,646 Government by the people. 318 00:18:15,681 --> 00:18:19,917 The first inklings, imperfect then as now, of a democracy, 319 00:18:19,952 --> 00:18:22,320 and the notion that the ordinary citizen 320 00:18:22,354 --> 00:18:24,255 might possess certain rights, 321 00:18:24,289 --> 00:18:27,858 come to us from this time and place. 322 00:18:28,761 --> 00:18:32,096 But in my view, the most revolutionary innovation of all 323 00:18:32,130 --> 00:18:35,933 to come to us from this ancient world was the idea 324 00:18:35,968 --> 00:18:39,804 that natural events were neither punishment nor reward 325 00:18:39,838 --> 00:18:41,973 from capricious gods. 326 00:18:42,007 --> 00:18:45,176 The workings of nature could be explained 327 00:18:45,210 --> 00:18:48,346 without invoking the supernatural. 328 00:18:48,380 --> 00:18:50,648 The first person to express this thought 329 00:18:50,682 --> 00:18:52,884 was a man named Thales. 330 00:18:52,918 --> 00:18:54,886 When the thunder clapped or the earth quaked, 331 00:18:54,920 --> 00:18:57,889 it was not because something you did had somehow displeased 332 00:18:57,923 --> 00:19:00,124 the very demanding gods. 333 00:19:00,158 --> 00:19:02,960 No, it was the result of natural processes 334 00:19:02,995 --> 00:19:05,496 that we were capable of understanding. 335 00:19:05,530 --> 00:19:09,233 Though none of the books he is said to have written survive, 336 00:19:09,268 --> 00:19:13,304 Thales kindled a flame that still burns to this day: 337 00:19:13,338 --> 00:19:15,373 The very idea of cosmos out of chaos, 338 00:19:15,407 --> 00:19:19,176 a universe governed by the order of natural laws 339 00:19:19,211 --> 00:19:21,178 that we can actually figure out. 340 00:19:21,813 --> 00:19:26,318 This is the epic adventure that began in the mind of Thales. 341 00:19:27,553 --> 00:19:30,888 Only a century following Thales' death, 342 00:19:30,923 --> 00:19:32,490 another genius came along. 343 00:19:32,524 --> 00:19:34,825 And he, more than any other, 344 00:19:34,860 --> 00:19:37,061 was the first to discover the existence 345 00:19:37,095 --> 00:19:40,097 of the hidden universes that surround us. 346 00:19:40,132 --> 00:19:44,202 Democritus of Abdera was a true scientist, 347 00:19:44,236 --> 00:19:47,605 a man with a passionate desire to know the cosmos 348 00:19:47,639 --> 00:19:49,407 and to have fun. 349 00:19:49,441 --> 00:19:52,743 This is the man who once said, "a life without parties 350 00:19:52,778 --> 00:19:56,180 would be like an endless road without an end." 351 00:19:56,215 --> 00:19:57,949 You mean, that's it? 352 00:19:57,983 --> 00:19:59,584 That's all there is? 353 00:19:59,618 --> 00:20:02,186 Just a bunch of atoms in a void? 354 00:20:02,221 --> 00:20:03,187 Yep. 355 00:20:04,890 --> 00:20:06,224 Well, think about it. 356 00:20:06,258 --> 00:20:08,025 The world has to be made 357 00:20:08,060 --> 00:20:11,362 of countless indivisible particles in a void. 358 00:20:11,396 --> 00:20:16,167 Otherwise, nothing could move or grow, be divided or changed. 359 00:20:17,469 --> 00:20:18,703 Without atoms 360 00:20:18,737 --> 00:20:20,120 and empty space for them to move in, 361 00:20:20,121 --> 00:20:24,452 the world would be solid ,static and dead. 362 00:20:24,455 --> 00:20:26,856 So, don't be sad, my friends. 363 00:20:26,891 --> 00:20:29,359 Just think of the infinite possibilities 364 00:20:29,393 --> 00:20:33,162 that arise from different arrangements of those atoms. 365 00:20:37,101 --> 00:20:38,635 Here's to the atoms 366 00:20:38,669 --> 00:20:42,705 in this cup and in this wine... 367 00:20:42,740 --> 00:20:45,208 And to the laughter they make possible. 368 00:20:47,244 --> 00:20:50,280 Dispersed through the Clay of the cup 369 00:20:50,314 --> 00:20:52,448 are microscopic mineral grains, 370 00:20:52,483 --> 00:20:55,118 different kinds of crystals, 371 00:20:55,152 --> 00:20:58,721 each with its own distinctive atomic architecture. 372 00:20:58,756 --> 00:21:01,224 Mineral structures are exquisite, 373 00:21:01,258 --> 00:21:04,227 but they have a limited repertoire. 374 00:21:04,261 --> 00:21:07,497 A grain of quartz is a lattice of the same three atoms 375 00:21:07,531 --> 00:21:11,367 repeated, without variation, over and over again. 376 00:21:13,270 --> 00:21:16,940 Even a relatively complex mineral lattice like topaz, 377 00:21:16,974 --> 00:21:19,409 composed of ten or so atoms, 378 00:21:19,443 --> 00:21:22,078 can only repeat the identical atomic structure 379 00:21:22,112 --> 00:21:24,113 again and again. 380 00:21:28,258 --> 00:21:30,444 To lift a matter into another dimension 381 00:21:30,446 --> 00:21:33,815 to free it from the lattice prison of endless repetition, 382 00:21:33,850 --> 00:21:36,285 you need an atom that can bond in all directions 383 00:21:36,319 --> 00:21:37,920 with other atoms like itself 384 00:21:37,954 --> 00:21:40,856 as well as with atoms of different kinds. 385 00:21:48,298 --> 00:21:50,799 Behold the carbon atom... 386 00:21:50,833 --> 00:21:54,002 the essential element for life on earth. 387 00:21:54,037 --> 00:21:56,472 Why? 388 00:21:56,906 --> 00:21:59,308 Carbon is special because it can bond with 389 00:21:59,342 --> 00:22:01,610 up to four other atoms at a time. 390 00:22:01,644 --> 00:22:04,379 It can connect with many different kinds of atoms, 391 00:22:04,414 --> 00:22:07,382 as well as other carbon atoms. 392 00:22:07,417 --> 00:22:09,051 It can curl into rings 393 00:22:09,085 --> 00:22:11,286 and string together into chains, 394 00:22:11,321 --> 00:22:15,724 building molecules far more complex than any crystal. 395 00:22:17,728 --> 00:22:21,830 No other atom has the same flexibility. 396 00:22:21,864 --> 00:22:24,299 Even atoms that have similar chemical properties, 397 00:22:24,311 --> 00:22:25,901 like silicon, 398 00:22:25,903 --> 00:22:28,036 can't form the amazing variety of molecules 399 00:22:28,039 --> 00:22:30,072 built on carbon. 400 00:22:30,106 --> 00:22:32,641 The carbon-based molecules we call proteins, 401 00:22:32,675 --> 00:22:34,843 the molecules of life, 402 00:22:34,844 --> 00:22:38,046 contain literally hundreds of thousands of atoms. 403 00:22:38,350 --> 00:22:42,017 Carbon atoms are the backbone of the molecules 404 00:22:42,051 --> 00:22:44,253 that make every living thing on earth, 405 00:22:44,287 --> 00:22:46,755 including us. 406 00:22:46,789 --> 00:22:50,025 That's the difference between rocks and living things. 407 00:22:51,694 --> 00:22:54,096 Life can make enormous molecules 408 00:22:54,130 --> 00:22:56,598 of stunning size and complexity, 409 00:22:56,633 --> 00:22:58,734 freeing matter to improvise, 410 00:22:58,768 --> 00:23:00,769 evolve, 411 00:23:00,803 --> 00:23:02,804 and even love. 412 00:23:33,764 --> 00:23:35,799 Take it easy, dad. 413 00:23:35,833 --> 00:23:38,235 He never actually touched her. 414 00:23:38,269 --> 00:23:40,370 In everyday life on our world, 415 00:23:40,404 --> 00:23:42,005 on the scale of atoms, 416 00:23:42,039 --> 00:23:45,909 material objects never really touch. 417 00:23:45,943 --> 00:23:49,346 Each atom has a tiny nucleus at its center, 418 00:23:49,380 --> 00:23:52,749 surrounded by an electron cloud of lines of force. 419 00:23:52,783 --> 00:23:55,252 As the atoms approach each other, 420 00:23:55,286 --> 00:23:57,220 the boy's electron clouds 421 00:23:57,255 --> 00:23:58,822 push away the girl's. 422 00:23:58,856 --> 00:24:02,993 More than 99.9% of the matter of any atom 423 00:24:03,027 --> 00:24:05,195 is concentrated in its nucleus. 424 00:24:05,229 --> 00:24:08,668 The nucleus is surrounded by an electron cloud 425 00:24:08,702 --> 00:24:11,071 which produces an invisible field of force, 426 00:24:11,105 --> 00:24:13,373 and acts like a shock absorber. 427 00:24:13,407 --> 00:24:16,042 The configuration of the electron cloud 428 00:24:16,076 --> 00:24:18,044 determines the nature of an element. 429 00:24:18,079 --> 00:24:20,713 In the ordinary course of things here on earth, 430 00:24:20,748 --> 00:24:22,615 the nuclei never touch. 431 00:24:22,650 --> 00:24:24,717 We have a sensation of touching, 432 00:24:24,752 --> 00:24:27,353 but that's really just our invisible force fields 433 00:24:27,388 --> 00:24:30,323 overlapping and repelling each other. 434 00:24:46,107 --> 00:24:48,541 The nucleus is very small 435 00:24:48,576 --> 00:24:50,210 compared to the rest of the atom. 436 00:24:50,244 --> 00:24:54,247 If an atom were the size of this cathedral, 437 00:24:54,281 --> 00:24:58,518 its nucleus would be the size of that mote of dust. 438 00:25:01,288 --> 00:25:05,492 An atom is mostly empty space. 439 00:25:05,526 --> 00:25:08,228 To understand the nature of matter, 440 00:25:08,262 --> 00:25:10,230 we have to go deeper still, 441 00:25:10,264 --> 00:25:13,266 to a place 100,000 times smaller than the atom: 442 00:25:13,300 --> 00:25:15,301 Its nucleus. 443 00:25:18,472 --> 00:25:20,240 The simplest and most plentiful atom 444 00:25:20,274 --> 00:25:22,909 in the cosmos is hydrogen. 445 00:25:22,943 --> 00:25:25,145 Its nucleus is a single proton, 446 00:25:25,179 --> 00:25:28,181 which makes hydrogen element number one. 447 00:25:28,215 --> 00:25:30,016 The clouds that surround it 448 00:25:30,050 --> 00:25:32,419 are the realms where the atom's lone electron 449 00:25:32,453 --> 00:25:34,988 is permitted to roam. 450 00:25:35,022 --> 00:25:38,258 What happens when you have a nucleus with two protons? 451 00:25:38,292 --> 00:25:39,926 Protons repel each other. 452 00:25:39,960 --> 00:25:42,295 In order to hold them together in a nucleus, 453 00:25:42,329 --> 00:25:45,498 you need other particles called neutrons. 454 00:25:45,533 --> 00:25:48,101 Their job is to keep the protons 455 00:25:48,135 --> 00:25:49,536 from getting out of line. 456 00:25:49,570 --> 00:25:51,671 They overwhelm the protons 457 00:25:51,705 --> 00:25:54,541 with their strong attractive nuclear force. 458 00:25:54,575 --> 00:25:57,811 A nucleus with two protons is element number two, 459 00:25:57,845 --> 00:26:00,480 otherwise known as helium. 460 00:26:00,514 --> 00:26:03,516 A nucleus with six protons is element number six, 461 00:26:03,551 --> 00:26:05,485 which is carbon, 462 00:26:05,519 --> 00:26:08,621 the fundamental building block of life. 463 00:26:08,656 --> 00:26:11,791 The nucleus of a gold atom has 79 protons. 464 00:26:11,826 --> 00:26:13,827 They attract 79 electrons 465 00:26:13,861 --> 00:26:15,662 in clouds around it. 466 00:26:15,696 --> 00:26:17,964 The way light interacts with those electrons 467 00:26:17,998 --> 00:26:20,564 is what makes gold glitter. 468 00:26:20,598 --> 00:26:23,533 Every additional proton in the nucleus 469 00:26:23,568 --> 00:26:26,837 requires enough neutrons to bind them together... 470 00:26:26,871 --> 00:26:28,505 Up to a point. 471 00:26:28,539 --> 00:26:30,740 There's an upper limit to the number of neutrons 472 00:26:30,742 --> 00:26:32,509 you can stuff into a nucleus 473 00:26:32,511 --> 00:26:34,277 before it becomes unstable. 474 00:26:34,279 --> 00:26:36,446 I know a place 475 00:26:36,448 --> 00:26:38,515 where the nuclei of different atoms 476 00:26:38,517 --> 00:26:40,517 actually do touch each other. 477 00:27:00,571 --> 00:27:03,073 The sun looks like a solid object, 478 00:27:03,075 --> 00:27:05,275 but it's not. 479 00:27:05,277 --> 00:27:08,211 It's so hot that all its atoms 480 00:27:08,213 --> 00:27:10,113 are always in their gaseous state. 481 00:27:10,115 --> 00:27:11,548 The bonds that join atoms 482 00:27:11,550 --> 00:27:13,316 to make solids and liquids on earth 483 00:27:13,318 --> 00:27:15,218 are not strong enough to withstand 484 00:27:15,220 --> 00:27:18,188 the heat of the boiling sun. 485 00:27:18,190 --> 00:27:21,057 Those arcing streams of incandescent gas 486 00:27:21,059 --> 00:27:23,260 that dwarf the earth 487 00:27:23,262 --> 00:27:25,395 are guided by magnetic lines of force 488 00:27:25,397 --> 00:27:28,465 that emanate from below the surface of the sun. 489 00:27:28,467 --> 00:27:31,001 Why is the sun so hot? 490 00:27:31,003 --> 00:27:33,303 Because its own stupendous gravity 491 00:27:33,305 --> 00:27:35,739 is squeezing its atoms together. 492 00:27:38,109 --> 00:27:40,744 The energy of gravity is being transformed 493 00:27:40,746 --> 00:27:42,879 into the energy of moving atoms. 494 00:27:42,881 --> 00:27:45,582 That's what heat is. 495 00:27:45,584 --> 00:27:47,451 The deeper we go into the sun, 496 00:27:47,453 --> 00:27:49,252 the greater the squeezing 497 00:27:49,254 --> 00:27:51,521 and the higher the temperature. 498 00:27:51,523 --> 00:27:53,090 In the heart of the sun, 499 00:27:53,092 --> 00:27:54,925 the atoms are moving so fast 500 00:27:54,927 --> 00:27:57,294 that when they collide, they fuse. 501 00:27:57,296 --> 00:28:00,931 Their nuclei touch. 502 00:28:00,933 --> 00:28:04,367 The sun is a nuclear fusion reactor, 503 00:28:04,369 --> 00:28:06,636 held together by its own gravity. 504 00:28:06,638 --> 00:28:09,973 It's balanced between the inward pull of gravity 505 00:28:09,975 --> 00:28:12,609 and the outward push of its hot gases. 506 00:28:16,547 --> 00:28:19,850 That balance has lasted billions of years, 507 00:28:19,884 --> 00:28:21,818 providing stability that made possible 508 00:28:21,853 --> 00:28:23,353 the evolution of life on earth. 509 00:28:23,387 --> 00:28:25,789 In the sun's core, 510 00:28:25,823 --> 00:28:27,691 the fusion of hydrogen into helium 511 00:28:27,725 --> 00:28:30,861 releases nuclear energy in the form of photons. 512 00:28:30,895 --> 00:28:32,529 These particles of light 513 00:28:32,563 --> 00:28:34,464 slowly work their way to the surface, 514 00:28:34,499 --> 00:28:36,199 where they're seen as sunlight. 515 00:28:36,234 --> 00:28:40,137 Helium is the ash of the sun's nuclear furnace. 516 00:28:42,140 --> 00:28:43,974 The sun is a medium-sized star. 517 00:28:44,008 --> 00:28:47,611 Its core is only a lukewarm ten million degrees... 518 00:28:47,645 --> 00:28:48,945 hot enough to fuse hydrogen, 519 00:28:48,980 --> 00:28:50,947 but too cold to fuse helium. 520 00:28:50,982 --> 00:28:53,350 There are many stars in the galaxy 521 00:28:53,384 --> 00:28:54,951 that get much hotter, 522 00:28:54,986 --> 00:28:56,486 because they're more massive 523 00:28:56,521 --> 00:28:58,054 and have more gravity. 524 00:28:58,089 --> 00:29:01,224 Such stars fuse helium into heavier elements, 525 00:29:01,259 --> 00:29:03,193 like carbon and oxygen. 526 00:29:03,227 --> 00:29:05,128 In their old age, 527 00:29:05,163 --> 00:29:07,831 they gently diffuse these elements into space. 528 00:29:10,234 --> 00:29:12,402 Other stars, more massive yet, 529 00:29:12,437 --> 00:29:14,704 live fast and die young 530 00:29:14,739 --> 00:29:16,706 in cataclysmic supernova explosions. 531 00:29:16,741 --> 00:29:19,910 In our galaxy, such stars go supernova 532 00:29:19,944 --> 00:29:21,344 about once a century. 533 00:29:23,781 --> 00:29:26,416 These explosions are far hotter than the core of the sun... 534 00:29:26,451 --> 00:29:29,352 hot enough to transform elements like iron 535 00:29:29,387 --> 00:29:31,721 into all the heavier ones 536 00:29:31,756 --> 00:29:34,925 and spew them into space. 537 00:29:34,959 --> 00:29:36,827 The large magellanic cloud 538 00:29:36,861 --> 00:29:39,029 is a neighboring galaxy of our milky way. 539 00:29:39,063 --> 00:29:41,698 It's visible in the skies of the Southern hemisphere. 540 00:29:42,800 --> 00:29:44,367 When a supernova explodes, 541 00:29:44,402 --> 00:29:45,936 its brightness rivals 542 00:29:45,970 --> 00:29:49,306 that of its entire galaxy. 543 00:29:59,050 --> 00:30:02,185 But all that light is only about one percent 544 00:30:02,220 --> 00:30:04,855 of the energy liberated in the explosion. 545 00:30:04,889 --> 00:30:07,958 The rest of the energy is carried off by the most common 546 00:30:07,992 --> 00:30:10,293 and the most mysterious particles in the cosmos. 547 00:30:10,328 --> 00:30:13,697 There are trillions of them passing through you right now, 548 00:30:13,731 --> 00:30:16,233 and yet tracking down even one of them 549 00:30:16,267 --> 00:30:19,903 will take us to one of the strangest places on earth. 550 00:30:27,501 --> 00:30:29,569 Stalking the wild neutrino 551 00:30:29,603 --> 00:30:31,404 is the rarest of sport. 552 00:30:31,438 --> 00:30:33,973 The lengths one must go to track them down 553 00:30:34,008 --> 00:30:35,742 is nothing short of astonishing. 554 00:30:35,776 --> 00:30:39,412 Welcome to Super Kamiokande, 555 00:30:39,446 --> 00:30:43,249 the subterranean Japanese neutrino detection chamber. 556 00:30:43,283 --> 00:30:46,419 We're more than a half mile beneath earth's surface. 557 00:30:46,453 --> 00:30:48,688 You might ask, "well, who in their right mind 558 00:30:48,722 --> 00:30:51,924 would bury an astronomical observatory so far underground?" 559 00:30:51,959 --> 00:30:55,495 Those who hunt the most elusive prey in the cosmos: 560 00:30:55,529 --> 00:30:57,497 The neutrino. 561 00:30:57,531 --> 00:30:59,499 This enormous array of light detectors 562 00:30:59,533 --> 00:31:02,568 surrounding 50,000 tons of distilled water 563 00:31:02,603 --> 00:31:06,072 is a trap designed to catch neutrinos only. 564 00:31:06,106 --> 00:31:08,508 Other particles, such as cosmic rays... 565 00:31:08,542 --> 00:31:11,511 mostly protons and electrons that rain down from space... 566 00:31:11,545 --> 00:31:14,113 cannot get through all that rock above us. 567 00:31:14,148 --> 00:31:17,517 But matter poses no obstacle to a neutrino. 568 00:31:17,551 --> 00:31:21,554 A neutrino could pass through 100 light-years of steel 569 00:31:21,588 --> 00:31:24,023 without even slowing down. 570 00:31:24,058 --> 00:31:26,759 Neutrinos hardly interact with matter at all. 571 00:31:26,794 --> 00:31:28,461 That's why you need so much of it 572 00:31:28,495 --> 00:31:30,063 to catch even one of them. 573 00:31:30,097 --> 00:31:32,131 On those rare occasions when a neutrino 574 00:31:32,166 --> 00:31:34,901 actually does collide with a particle of ordinary matter, 575 00:31:34,935 --> 00:31:39,105 it produces a ghostly, ring-shaped flash of light. 576 00:31:39,139 --> 00:31:41,808 We're lying in wait 577 00:31:41,842 --> 00:31:45,411 for a particle that weighs next to nothing. 578 00:31:45,446 --> 00:31:47,413 Even the miniscule electron 579 00:31:47,448 --> 00:31:50,416 has more than a million times its mass... 580 00:31:50,451 --> 00:31:52,118 There! 581 00:31:52,152 --> 00:31:54,320 When the supernova in the large magellanic cloud 582 00:31:54,355 --> 00:31:56,622 blew its top in 1987, 583 00:31:56,657 --> 00:31:59,559 this is what it would have looked like in here. 584 00:31:59,593 --> 00:32:01,995 Now remember, the large magellanic cloud 585 00:32:02,029 --> 00:32:03,329 is in our Southern hemisphere, 586 00:32:03,364 --> 00:32:04,931 so the neutrinos didn't come through 587 00:32:04,965 --> 00:32:06,566 that half-mile of rock above us, 588 00:32:06,600 --> 00:32:09,168 they had to pass through the thousands of miles 589 00:32:09,203 --> 00:32:12,005 of rock and iron below us to reach this detector. 590 00:32:12,039 --> 00:32:14,674 But the coolest thing was that those neutrinos 591 00:32:14,708 --> 00:32:17,310 hit earth three hours before 592 00:32:17,344 --> 00:32:19,345 the light from the supernova did. 593 00:32:19,380 --> 00:32:21,581 If nothing can travel faster than light, 594 00:32:21,615 --> 00:32:24,017 how could that possibly be? 595 00:32:29,623 --> 00:32:32,492 This is a dead star walking. 596 00:32:32,526 --> 00:32:35,995 It may look normal, but deep within it 597 00:32:36,030 --> 00:32:38,464 something cataclysmic is happening. 598 00:32:38,499 --> 00:32:40,833 This blue super giant star 599 00:32:40,868 --> 00:32:45,305 has already begun to explode inside. 600 00:32:48,909 --> 00:32:52,478 Like rats deserting a sinking ship, the neutrinos 601 00:32:52,513 --> 00:32:54,981 produced in the heart of the exploding star 602 00:32:55,015 --> 00:32:57,550 race outward at near the speed of light, 603 00:32:57,584 --> 00:32:59,953 through overlying mass 604 00:32:59,987 --> 00:33:01,554 in only a few seconds. 605 00:33:01,588 --> 00:33:03,790 But the shock wave of the exploding gas 606 00:33:03,824 --> 00:33:06,826 plods along from the center of the star 607 00:33:06,860 --> 00:33:09,462 at 1/10,000 the speed of light 608 00:33:09,496 --> 00:33:11,698 until it finally reaches 609 00:33:11,732 --> 00:33:13,166 the star's surface, 610 00:33:13,200 --> 00:33:16,936 turning it into supernova 1987a. 611 00:33:23,043 --> 00:33:24,711 It took hours for the explosion 612 00:33:24,745 --> 00:33:27,313 to reach the surface of the star and blow it wide open, 613 00:33:27,348 --> 00:33:29,148 exposing the super hot core. 614 00:33:29,183 --> 00:33:32,218 The neutrinos had an insurmountable head start. 615 00:33:32,252 --> 00:33:35,054 That's why the flash of light arrived on earth 616 00:33:35,089 --> 00:33:38,057 so much later than the shower of neutrinos. 617 00:33:38,092 --> 00:33:41,527 Before anyone had ever snared the wild neutrino, 618 00:33:41,562 --> 00:33:45,431 it existed in the mind of a theoretical physicist. 619 00:33:45,466 --> 00:33:48,501 Just as Charles Darwin knew 620 00:33:48,535 --> 00:33:51,104 there must be an extremely long-nosed creature 621 00:33:51,138 --> 00:33:53,106 flying around somewhere in Madagascar, 622 00:33:53,140 --> 00:33:56,976 a 20th-century physicist named Wolfgang Pauli... 623 00:33:59,980 --> 00:34:01,914 was desperately seeking a particle 624 00:34:01,949 --> 00:34:04,217 to rescue one of the pillars of modern physics, 625 00:34:04,251 --> 00:34:07,587 the law of the conservation of energy. 626 00:34:16,430 --> 00:34:18,464 So why didn't I flinch? 627 00:34:18,499 --> 00:34:20,767 Because the laws of science differ fundamentally 628 00:34:20,801 --> 00:34:22,602 from those of other human endeavors. 629 00:34:22,636 --> 00:34:26,139 In order for an idea to become a scientific law, 630 00:34:26,173 --> 00:34:27,974 it has to unbreakable. 631 00:34:28,008 --> 00:34:30,743 That's why I was willing to bet this face 632 00:34:30,778 --> 00:34:33,646 on the laws of conservation of energy. 633 00:34:33,681 --> 00:34:36,082 Now, if you try this at home, 634 00:34:36,116 --> 00:34:39,085 take care not to give the cannonball a push. 635 00:34:39,119 --> 00:34:40,720 That's adding energy, 636 00:34:40,754 --> 00:34:43,289 and the ball will surely come back and do some damage. 637 00:34:43,324 --> 00:34:46,326 You just have to let it go, like this. 638 00:34:47,528 --> 00:34:48,828 By lifting the ball, 639 00:34:48,862 --> 00:34:50,563 you give it gravitational energy, 640 00:34:50,597 --> 00:34:53,566 which is the potential to fall and accelerate. 641 00:34:53,600 --> 00:34:55,134 The cannonball is going fastest 642 00:34:55,169 --> 00:34:56,803 when it's at the bottom of its arc, 643 00:34:56,837 --> 00:34:58,471 and at that moment, 644 00:34:58,505 --> 00:35:00,673 it's converted all of its gravitational energy 645 00:35:00,708 --> 00:35:02,742 to the energy of motion. 646 00:35:02,776 --> 00:35:05,445 As it swings, the cannonball is constantly exchanging 647 00:35:05,479 --> 00:35:07,680 one of these two kinds of energy for the other, 648 00:35:07,715 --> 00:35:10,917 but the total amount of energy remains constant. 649 00:35:10,951 --> 00:35:14,287 That's an example of the law of conservation of energy. 650 00:35:14,321 --> 00:35:16,756 Once the cannonball is released, 651 00:35:16,790 --> 00:35:19,826 it can never gain more energy than it had to begin with. 652 00:35:19,860 --> 00:35:23,162 It has no way to fly up and break my nose. 653 00:35:23,197 --> 00:35:27,166 The energy accounting books are always strictly balanced. 654 00:35:27,201 --> 00:35:29,535 There's no such thing as cheating. 655 00:35:29,570 --> 00:35:31,371 So in the 20th century, 656 00:35:31,405 --> 00:35:34,774 when physicists first calculated the energy of atoms precisely, 657 00:35:34,808 --> 00:35:36,042 they were startled to discover 658 00:35:36,076 --> 00:35:38,578 an apparent violation of this law. 659 00:35:40,681 --> 00:35:43,149 They found that in some radioactive atoms, 660 00:35:43,183 --> 00:35:46,552 the nucleus can spontaneously eject an electron. 661 00:35:46,587 --> 00:35:50,123 This transforms the atom into a different element. 662 00:35:50,157 --> 00:35:52,692 The physicists were mystified. 663 00:35:52,726 --> 00:35:54,794 The energy of the escaped electron 664 00:35:54,828 --> 00:35:56,796 plus that of the new element 665 00:35:56,830 --> 00:36:00,133 adds up to less than the energy in the original nucleus. 666 00:36:00,167 --> 00:36:02,035 But the law says, 667 00:36:02,069 --> 00:36:04,971 "thou shall not destroy or create energy." 668 00:36:05,005 --> 00:36:07,840 So where did the missing energy go? 669 00:36:07,875 --> 00:36:10,009 In 1930... 670 00:36:10,044 --> 00:36:12,579 Wolfgang Pauli predicted 671 00:36:12,613 --> 00:36:14,714 there must be an undiscovered particle, 672 00:36:14,748 --> 00:36:17,183 one that makes off with the missing energy. 673 00:36:17,217 --> 00:36:19,986 At the time, Pauli lamented 674 00:36:20,020 --> 00:36:23,423 that such a phantom particle might be so minute, 675 00:36:23,457 --> 00:36:25,358 swift and evasive 676 00:36:25,392 --> 00:36:28,428 as to forever defy detection. 677 00:36:28,462 --> 00:36:31,864 But that was a rare failure of his imagination 678 00:36:31,899 --> 00:36:34,067 because science is always searching 679 00:36:34,101 --> 00:36:35,935 for a way to go deeper still. 680 00:36:35,970 --> 00:36:37,870 A generation later, 681 00:36:37,905 --> 00:36:40,240 Pauli's neutrinos were actually detected for the first time 682 00:36:40,274 --> 00:36:42,842 in radiation from a nuclear reactor. 683 00:36:42,876 --> 00:36:46,779 And we've been finding them, with difficulty, ever since. 684 00:36:46,814 --> 00:36:49,682 There are scientists today 685 00:36:49,717 --> 00:36:52,952 who are trying to find a way to ride those neutrinos 686 00:36:52,987 --> 00:36:56,489 all the way back to the beginning of time. 687 00:36:57,992 --> 00:36:59,859 We'll go as far as they have gone 688 00:36:59,894 --> 00:37:03,830 to come up against the wall of forever. 689 00:37:10,894 --> 00:37:13,629 The wall of forever is nothing new. 690 00:37:13,663 --> 00:37:15,597 Our ancestors came up against it 691 00:37:15,632 --> 00:37:18,734 almost as soon as they first started imagining it. 692 00:37:18,768 --> 00:37:23,539 A million dawns ago, in the 13th century bc, 693 00:37:23,573 --> 00:37:27,076 the Egyptian this temple at Abu Simbel 694 00:37:27,078 --> 00:37:29,144 to honor the Pharaoh Ramses II, 695 00:37:29,179 --> 00:37:32,381 depicted here in four colossal statues. 696 00:37:32,415 --> 00:37:35,317 Reigning even above even this mighty king 697 00:37:35,322 --> 00:37:38,320 is the falcon-headed Ra-Harakhti, 698 00:37:38,325 --> 00:37:40,589 God of the sun. 699 00:37:45,028 --> 00:37:47,129 The temple was designed 700 00:37:47,130 --> 00:37:48,897 so that the light from the rising sun 701 00:37:48,932 --> 00:37:53,235 could only enter the sanctuary on two days every year. 702 00:37:53,270 --> 00:37:56,272 As the rays enter the temple, 703 00:37:56,306 --> 00:37:58,240 they burnish the statues of the gods 704 00:37:58,275 --> 00:37:59,908 with their golden light 705 00:37:59,943 --> 00:38:03,913 before penetrating the sanctuary. 706 00:38:03,947 --> 00:38:07,917 Even then, one God remains in shadow. 707 00:38:07,921 --> 00:38:10,419 Ptah, lord of creation, 708 00:38:10,423 --> 00:38:12,655 as if the origin of the universe 709 00:38:12,659 --> 00:38:15,224 must forever be concealed. 710 00:38:19,229 --> 00:38:22,031 Feel the sun on your face. 711 00:38:22,065 --> 00:38:24,633 The energy that warms you 712 00:38:24,668 --> 00:38:27,803 began its journey some ten million years ago 713 00:38:27,837 --> 00:38:29,939 in the heart of the sun. 714 00:38:31,973 --> 00:38:33,008 Unlike neutrinos, 715 00:38:33,043 --> 00:38:34,843 the photons needed 716 00:38:34,845 --> 00:38:37,846 that long to work their way out from the core to the surface. 717 00:38:37,881 --> 00:38:39,882 Why? 718 00:38:39,916 --> 00:38:42,818 Because they were colliding billions of times per second 719 00:38:42,819 --> 00:38:45,120 with the sun's atoms, every collision 720 00:38:45,125 --> 00:38:48,123 sending them off in a random direction. 721 00:38:48,158 --> 00:38:50,125 But once they finally reached the surface, 722 00:38:50,160 --> 00:38:51,560 they were free 723 00:38:51,562 --> 00:38:54,296 to dash nonstop, at the speed of light, 724 00:38:54,331 --> 00:38:56,532 in a mere eight minutes and 20 seconds 725 00:38:56,566 --> 00:38:58,334 from the sun to you. 726 00:39:00,070 --> 00:39:03,205 Ten-million-year-old light on your face. 727 00:39:05,575 --> 00:39:07,843 What was happening 728 00:39:07,878 --> 00:39:11,213 when that light left the heart of the sun? 729 00:39:16,119 --> 00:39:19,154 The cosmic calendar compresses 730 00:39:19,159 --> 00:39:21,991 the entire 13.8 billion year history 731 00:39:21,995 --> 00:39:24,093 of the universe into a single year. 732 00:39:24,127 --> 00:39:27,663 Every month represents about a billion years. 733 00:39:27,697 --> 00:39:30,566 Every day, about 40 million years. 734 00:39:30,600 --> 00:39:33,836 The universe is so old that, on the cosmic calendar, 735 00:39:33,870 --> 00:39:37,606 ten million years ago only takes us back as far as... 736 00:39:37,641 --> 00:39:41,243 6:00 P.M. on the last evening 737 00:39:41,278 --> 00:39:44,113 of the last day of the year. 738 00:39:44,147 --> 00:39:45,714 And what about us? 739 00:39:45,749 --> 00:39:47,583 Humans had yet to evolve. 740 00:39:47,617 --> 00:39:49,351 Ten million years ago, 741 00:39:49,386 --> 00:39:51,787 our ancestors were anthropoid apes, 742 00:39:51,821 --> 00:39:53,722 swinging through the trees of Africa. 743 00:39:53,757 --> 00:39:57,226 To us, ten million years seems like a long time, 744 00:39:57,260 --> 00:39:59,628 but it's only the length of an afternoon 745 00:39:59,663 --> 00:40:02,131 on the timescale of the cosmos. 746 00:40:05,468 --> 00:40:08,070 The sun began fusing hydrogen 747 00:40:08,104 --> 00:40:10,406 4,500 million years ago... 748 00:40:10,440 --> 00:40:14,143 August 31 on the cosmic calendar. 749 00:40:14,177 --> 00:40:16,212 Our milky way galaxy 750 00:40:16,213 --> 00:40:19,315 is about 10,000 million years old. 751 00:40:19,320 --> 00:40:24,420 The first galaxies formed about a few billion years earlier. 752 00:40:24,421 --> 00:40:28,390 And something keeps me from going any further back in time. 753 00:40:28,425 --> 00:40:30,426 What is this? 754 00:40:34,097 --> 00:40:35,965 It's the nature of light and time. 755 00:40:35,999 --> 00:40:39,168 Because light travels at a finite speed, 756 00:40:39,202 --> 00:40:41,470 to look across space 757 00:40:41,505 --> 00:40:44,173 is to look back in time. 758 00:40:47,110 --> 00:40:49,245 So the farther we see, 759 00:40:49,279 --> 00:40:52,081 the older the light. 760 00:40:52,115 --> 00:40:54,917 This is as far back in the history of the cosmos 761 00:40:54,951 --> 00:40:56,919 as we can see with light. 762 00:40:56,953 --> 00:40:59,355 It's a baby picture of universe, 763 00:40:59,389 --> 00:41:02,458 when it was only 380,000 years old. 764 00:41:02,492 --> 00:41:06,262 That's 15 minutes into January 1st 765 00:41:06,296 --> 00:41:08,130 on the cosmic calendar. 766 00:41:08,165 --> 00:41:11,300 If we look as far as we can see in any direction 767 00:41:11,334 --> 00:41:13,302 using microwave telescopes, 768 00:41:13,336 --> 00:41:14,770 this is what we see, 769 00:41:14,805 --> 00:41:18,107 the glow left over from the Big Bang. 770 00:41:18,111 --> 00:41:20,109 Imagine that all the matter and energy 771 00:41:20,113 --> 00:41:22,011 of the observable universe 772 00:41:22,045 --> 00:41:23,779 was concentrated into something 773 00:41:23,814 --> 00:41:26,315 no larger than this. 774 00:41:26,349 --> 00:41:30,219 That's the size of the universe 775 00:41:30,253 --> 00:41:32,621 when it was a trillionth of a trillionth 776 00:41:32,656 --> 00:41:35,624 of a trillionth of a second old. 777 00:41:35,659 --> 00:41:39,195 All the matter and energy of the hundred billion galaxies 778 00:41:39,229 --> 00:41:42,298 now splayed out across the billions of light-years 779 00:41:42,332 --> 00:41:44,300 were once pent up 780 00:41:44,334 --> 00:41:46,669 in something the size of a marble. 781 00:41:46,703 --> 00:41:48,737 Can you imagine how tightly packed 782 00:41:48,772 --> 00:41:50,639 that marble must have been? 783 00:41:50,674 --> 00:41:53,509 Far too dense for any kind of light to move through it, 784 00:41:53,543 --> 00:41:57,313 but no obstacle for the likes of neutrinos. 785 00:41:57,347 --> 00:42:00,216 The big bang must have produced stupendous numbers of neutrinos, 786 00:42:00,250 --> 00:42:01,817 which flew unhindered 787 00:42:01,822 --> 00:42:03,919 through that inconceivable crush of matter. 788 00:42:03,954 --> 00:42:07,156 The very thing that makes them almost impossible to detect 789 00:42:07,190 --> 00:42:11,260 is what allows neutrinos to sail through the curtain 790 00:42:11,294 --> 00:42:13,929 that conceals the beginning of time. 791 00:42:13,964 --> 00:42:15,531 Where are they now? 792 00:42:15,565 --> 00:42:17,099 They are here, they're there, 793 00:42:17,100 --> 00:42:19,335 everywhere throughout the universe. 794 00:42:19,369 --> 00:42:22,204 Neutrinos from creation are within you. 795 00:42:23,273 --> 00:42:25,508 From a marble... 796 00:42:25,542 --> 00:42:27,543 To the cosmos. 797 00:42:38,088 --> 00:42:41,590 This is the road that Thales and Democritus put us on 798 00:42:41,625 --> 00:42:44,393 some 2,500 years ago... 799 00:42:44,427 --> 00:42:46,462 a road of endless searching, 800 00:42:46,496 --> 00:42:49,799 a relentless, systematic hunt for new worlds 801 00:42:49,833 --> 00:42:52,468 and an ever-deepening understanding of nature. 802 00:42:53,937 --> 00:42:56,806 Who among you will pick up that torch 803 00:42:56,840 --> 00:43:00,443 and take us down that next stretch of road?