1 00:00:03,983 --> 00:00:07,557 We live on one level of existence, but there are others. 2 00:00:08,581 --> 00:00:12,258 These hidden dimensions of reality are everywhere. 3 00:00:12,266 --> 00:00:14,759 Far away, across the light years. 4 00:00:14,819 --> 00:00:16,058 Beneath our feet. 5 00:00:16,060 --> 00:00:19,361 And even inside you and me. 6 00:00:19,702 --> 00:00:22,161 We are made of atoms. 7 00:00:24,093 --> 00:00:25,862 There are more atoms in your eye, 8 00:00:25,997 --> 00:00:29,397 than there are stars and all the galaxies of the known universe. 9 00:00:34,163 --> 00:00:36,298 The same is true of any solid object 10 00:00:36,332 --> 00:00:39,034 larger than the tip of your little finger. 11 00:00:39,068 --> 00:00:42,904 I'm a collection of three billion, billion, billion 12 00:00:42,939 --> 00:00:45,840 intricately arranged atoms called Neil Degrasse Tyson. 13 00:00:45,875 --> 00:00:50,711 You are a similar collection with a different name. 14 00:00:50,745 --> 00:00:52,246 We don't usually think of ourselves this way 15 00:00:52,280 --> 00:00:56,317 because that level of reality lies beyond the realm of our senses. 16 00:00:56,351 --> 00:00:58,552 But we're not gonna let that stop us. 17 00:00:58,587 --> 00:01:01,755 We can go deeper into the wonder. 18 00:02:39,188 --> 00:02:40,688 "Deeper, Deeper, Deeper Still" 19 00:02:46,379 --> 00:02:48,880 Atoms let matter do funny things. 20 00:02:48,915 --> 00:02:51,850 To understand water, you need to know what its atoms are doing. 21 00:02:51,884 --> 00:02:54,386 Every molecule of water is composed 22 00:02:54,420 --> 00:02:55,953 of two tiny hydrogen atoms 23 00:02:55,988 --> 00:02:58,623 attached to a larger oxygen atom. 24 00:02:58,657 --> 00:03:00,725 That's why we call it H20. 25 00:03:00,759 --> 00:03:03,861 If it's not too hot or too cold, 26 00:03:03,896 --> 00:03:06,564 the molecules can slide and tumble past each other. 27 00:03:06,598 --> 00:03:08,866 There's still some stickiness between the molecules, 28 00:03:08,900 --> 00:03:12,136 but not enough to lock them into a rigid solid. 29 00:03:12,170 --> 00:03:14,906 That's what makes something a liquid. 30 00:03:14,940 --> 00:03:16,574 The sun warms the water. 31 00:03:16,608 --> 00:03:17,975 And with more energy, 32 00:03:18,010 --> 00:03:19,911 the molecules move faster. 33 00:03:19,945 --> 00:03:21,711 That's all that temperature is. 34 00:03:21,746 --> 00:03:23,713 Those molecules are moving fast enough 35 00:03:23,748 --> 00:03:26,883 to break the weak bonds that hold them to their neighbors. 36 00:03:26,918 --> 00:03:28,785 That's evaporation. 37 00:03:28,819 --> 00:03:30,720 The air we breathe is made of 38 00:03:30,755 --> 00:03:32,756 nitrogen and oxygen molecules 39 00:03:32,790 --> 00:03:36,559 with a scattering of water vapor and carbon dioxide. 40 00:03:36,594 --> 00:03:38,561 Incoming! 41 00:03:38,596 --> 00:03:40,830 That's condensation. 42 00:03:40,865 --> 00:03:43,433 A dewdrop is the momentary triumph 43 00:03:43,467 --> 00:03:45,569 of condensation over evaporation. 44 00:03:45,603 --> 00:03:47,336 And while it lasts, 45 00:03:47,370 --> 00:03:50,806 it's a little cosmos with its own worlds... 46 00:03:50,840 --> 00:03:54,109 creatures, drama. 47 00:03:54,144 --> 00:03:56,345 To explore the far-flung realms 48 00:03:56,379 --> 00:03:57,613 of this dewdrop, 49 00:03:57,647 --> 00:03:59,014 we're gonna need a ship. 50 00:04:00,317 --> 00:04:02,251 One with twin engines... 51 00:04:02,285 --> 00:04:04,653 science and imagination. 52 00:04:10,627 --> 00:04:12,527 That's a single-celled paramecium, 53 00:04:12,561 --> 00:04:15,330 one of a multitude of skilled hunter-warriors 54 00:04:15,364 --> 00:04:17,966 that roam the dewdrop. 55 00:04:18,000 --> 00:04:20,535 But they, too, are hunted. 56 00:04:22,371 --> 00:04:25,139 The Dileptus. The paramecium's mortal enemy. 57 00:04:25,174 --> 00:04:28,943 The paramecium might get lucky and score a direct hit. 58 00:04:28,978 --> 00:04:30,645 Even if it doesn't, 59 00:04:30,679 --> 00:04:33,214 the recoil from the barrage will put some distance 60 00:04:33,249 --> 00:04:35,083 between the paramecium and its attacker. 61 00:04:37,853 --> 00:04:40,120 What can I say? 62 00:04:40,154 --> 00:04:41,922 That's life in the dewdrop. 63 00:04:54,002 --> 00:04:56,503 That little guy is tardigrade, 64 00:04:56,538 --> 00:04:59,940 an animal smaller than the head of a pin. 65 00:05:02,343 --> 00:05:04,343 Don't underestimate them. 66 00:05:04,378 --> 00:05:06,345 Tardigrades have been living on this planet 67 00:05:06,380 --> 00:05:07,647 a lot longer than we have. 68 00:05:07,681 --> 00:05:10,449 About 500 million years. 69 00:05:12,920 --> 00:05:14,921 For every one of us, 70 00:05:14,955 --> 00:05:18,124 there's at least a billion of them. 71 00:05:21,194 --> 00:05:23,496 They can make a living anywhere on earth. 72 00:05:23,530 --> 00:05:27,166 In the frigid peaks of the tallest mountains, 73 00:05:27,201 --> 00:05:29,035 in the cauldrons of erupting volcanoes, 74 00:05:29,069 --> 00:05:31,570 and in the deep ocean vents at the bottom of the sea. 75 00:05:31,604 --> 00:05:33,004 Tardigrades are so tough, 76 00:05:33,039 --> 00:05:34,339 they can survive naked 77 00:05:34,373 --> 00:05:36,441 in the vacuum of space. 78 00:05:36,475 --> 00:05:38,777 They've survived all five 79 00:05:38,811 --> 00:05:41,112 of the most recent mass extinctions on this planet. 80 00:05:41,147 --> 00:05:44,416 A visitor from another world could be forgiven 81 00:05:44,450 --> 00:05:47,819 for thinking of earth as the planet of the tardigrades. 82 00:05:51,591 --> 00:05:53,191 If we're ever gonna get to the bottom of this dewdrop, 83 00:05:53,226 --> 00:05:55,559 better get a move on. 84 00:05:58,063 --> 00:06:01,198 Every leaf and tiny clump of moss 85 00:06:01,233 --> 00:06:03,200 has hundreds of thousands 86 00:06:03,235 --> 00:06:05,703 of microscopic mouths called Stomata. 87 00:06:05,737 --> 00:06:07,705 Plants breathe through them, 88 00:06:07,739 --> 00:06:09,206 taking in carbon dioxide 89 00:06:09,241 --> 00:06:12,076 and exhaling the oxygen that we need to live. 90 00:06:12,110 --> 00:06:14,411 The plants can survive without us. 91 00:06:14,446 --> 00:06:16,647 But we and all the other animals... 92 00:06:16,681 --> 00:06:19,817 we'd be toast without them. 93 00:06:19,851 --> 00:06:22,051 The plants make food out of sunlight. 94 00:06:22,086 --> 00:06:24,454 We animals can't do that. 95 00:06:24,488 --> 00:06:26,422 To see how they do it, 96 00:06:26,457 --> 00:06:27,957 we have to go deeper, 97 00:06:27,992 --> 00:06:30,059 make ourselves about a thousand times smaller 98 00:06:30,094 --> 00:06:32,829 to get into their treasure house, 99 00:06:32,863 --> 00:06:34,597 the place where they keep the good stuff... 100 00:06:34,632 --> 00:06:36,499 the chlorophyll. 101 00:06:36,534 --> 00:06:37,967 That's the molecule 102 00:06:38,002 --> 00:06:41,104 that converts sunlight into energy. 103 00:06:44,008 --> 00:06:46,175 Every one of those rectangles is a plant cell. 104 00:06:46,210 --> 00:06:48,177 And those tiny green vehicles 105 00:06:48,211 --> 00:06:51,079 are its energy factories. 106 00:06:51,114 --> 00:06:52,681 If we could steal their trade secrets, 107 00:06:52,715 --> 00:06:55,250 it would trigger a new industrial revolution. 108 00:06:55,285 --> 00:06:57,085 But to spy on them, 109 00:06:57,120 --> 00:06:59,054 we're gonna need to go deeper still. 110 00:07:12,602 --> 00:07:15,236 What alien world has the ship of the imagination 111 00:07:15,271 --> 00:07:17,505 carried us to this time? 112 00:07:17,540 --> 00:07:19,741 It's the cosmos... 113 00:07:19,775 --> 00:07:23,411 Contained within a dewdrop. 114 00:07:23,446 --> 00:07:26,381 We're on an industrial espionage mission. 115 00:07:26,415 --> 00:07:28,850 If we can penetrate the trade secrets 116 00:07:28,884 --> 00:07:31,753 of the manufacturing process in that chloroplast, 117 00:07:31,787 --> 00:07:34,589 let's just say our whole future hangs in the balance. 118 00:07:34,623 --> 00:07:37,859 This chloroplast is using sunlight 119 00:07:37,893 --> 00:07:39,561 to break water molecules 120 00:07:39,595 --> 00:07:42,062 into atoms of hydrogen and oxygen. 121 00:07:42,096 --> 00:07:44,364 It combines the hydrogen with carbon dioxide 122 00:07:44,399 --> 00:07:46,066 to make sugar, 123 00:07:46,101 --> 00:07:49,403 and releases the oxygen as a waste product. 124 00:07:49,437 --> 00:07:52,272 To see how it happens, we have to go even deeper, 125 00:07:52,307 --> 00:07:53,907 get even smaller. 126 00:07:53,942 --> 00:07:57,177 We're talking atomic scale. 127 00:07:57,212 --> 00:07:58,846 Bingo. 128 00:07:58,880 --> 00:08:00,781 This assembly line is the heart 129 00:08:00,815 --> 00:08:02,516 of the molecular industrial complex. 130 00:08:02,550 --> 00:08:04,518 At the molecular level, 131 00:08:04,552 --> 00:08:06,552 things happen too fast for us to see. 132 00:08:06,587 --> 00:08:08,955 So we'll have to slow them down 133 00:08:08,989 --> 00:08:11,224 about a billion times. 134 00:08:14,328 --> 00:08:16,129 Those larger molecules are carbon dioxide. 135 00:08:16,163 --> 00:08:17,630 Each one of them is made 136 00:08:17,664 --> 00:08:19,532 of one carbon and two oxygen atoms. 137 00:08:19,566 --> 00:08:22,735 When sunlight strikes a green molecule of chlorophyll, 138 00:08:22,770 --> 00:08:25,905 it sets in motion a series of chemical reactions, 139 00:08:25,939 --> 00:08:27,740 breaking apart water molecules 140 00:08:27,775 --> 00:08:30,576 and freeing energetic electrons. 141 00:08:32,812 --> 00:08:34,446 And that's just the day shift, 142 00:08:34,480 --> 00:08:37,315 when sunlight supplies the incoming stream of energy. 143 00:08:37,350 --> 00:08:40,285 There's a second shift that works day and night 144 00:08:40,319 --> 00:08:43,155 using the solar energy kept in reserve. 145 00:08:44,824 --> 00:08:47,392 The energy of the free electrons is put to work, 146 00:08:47,427 --> 00:08:51,596 combining carbon dioxide with hydrogen from the water. 147 00:08:51,631 --> 00:08:56,301 The end product is sugar, which stores the solar energy. 148 00:08:56,335 --> 00:08:59,270 The chloroplast is a three-billion-year-old 149 00:08:59,304 --> 00:09:01,806 solar energy collector. 150 00:09:01,840 --> 00:09:04,575 This sub-microscopic solar battery 151 00:09:04,609 --> 00:09:07,111 is what drives all the forests and the fields 152 00:09:07,145 --> 00:09:09,346 and the plankton of the seas. 153 00:09:09,381 --> 00:09:11,081 And the animals. 154 00:09:11,116 --> 00:09:13,150 Including us. 155 00:09:13,185 --> 00:09:15,486 The solar-powered biosphere 156 00:09:15,520 --> 00:09:18,823 collects and processes six times more power 157 00:09:18,857 --> 00:09:21,025 than our entire civilization. 158 00:09:21,059 --> 00:09:22,959 We understand on a chemical level 159 00:09:22,993 --> 00:09:24,661 how photosynthesis works. 160 00:09:24,695 --> 00:09:26,796 We can recreate the process in a laboratory. 161 00:09:26,831 --> 00:09:29,599 But we're not as good at it as plants are. 162 00:09:29,633 --> 00:09:31,668 And it's not surprising, 163 00:09:31,702 --> 00:09:34,104 considering nature has been at this for billions of years, 164 00:09:34,138 --> 00:09:36,206 and we've only just started. 165 00:09:36,240 --> 00:09:37,774 But if we could figure out 166 00:09:37,808 --> 00:09:40,043 the trade secrets of photosynthesis, 167 00:09:40,077 --> 00:09:42,312 every of other source of energy 168 00:09:42,346 --> 00:09:43,980 we depend on today... 169 00:09:44,014 --> 00:09:46,616 coal, oil, natural gas... 170 00:09:46,650 --> 00:09:49,051 would become obsolete. 171 00:09:49,085 --> 00:09:51,720 Photosynthesis is the ultimate green power. 172 00:09:51,755 --> 00:09:53,622 It doesn't pollute the air 173 00:09:53,656 --> 00:09:56,024 and is, in fact, carbon neutral. 174 00:09:56,059 --> 00:09:58,994 Artificial photosynthesis on a big enough scale 175 00:09:59,028 --> 00:10:01,029 could reduce the greenhouse effect 176 00:10:01,064 --> 00:10:04,199 that's driving climate change in a dangerous direction. 177 00:10:04,234 --> 00:10:06,735 Uh-oh, place is evaporating. 178 00:10:06,770 --> 00:10:08,203 Time to get out of here. 179 00:10:10,840 --> 00:10:13,308 How fleeting is the life of a dewdrop. 180 00:10:13,343 --> 00:10:16,511 It condenses from thin air in the cool of the night, 181 00:10:16,545 --> 00:10:18,679 only to vanish with the heat of the day. 182 00:10:18,714 --> 00:10:21,582 And what of its inhabitants, the tardigrades? 183 00:10:21,617 --> 00:10:23,317 They'll be fine. 184 00:10:23,352 --> 00:10:25,753 They can go without water for years. 185 00:10:26,855 --> 00:10:28,723 It's hard to imagine, 186 00:10:28,757 --> 00:10:30,391 but plants covered the surface of the earth 187 00:10:30,426 --> 00:10:33,194 for hundreds of millions of years 188 00:10:33,228 --> 00:10:36,664 before they put forth their first flower. 189 00:10:36,698 --> 00:10:39,566 That was about a hundred million years ago, 190 00:10:39,600 --> 00:10:42,235 shortly before the dinosaurs were wiped out. 191 00:10:42,270 --> 00:10:46,406 Our world must've been a relatively drab-looking place back then, 192 00:10:46,441 --> 00:10:49,676 dominated by shades of green and brown. 193 00:10:49,710 --> 00:10:54,014 Yeah, there were giant trees and ferns and other plant life, 194 00:10:54,048 --> 00:10:56,283 but not the purple of an iris 195 00:10:56,317 --> 00:10:59,453 or the crimson of a red, red rose. 196 00:11:05,826 --> 00:11:08,861 Orchids were among the first flowering species 197 00:11:08,895 --> 00:11:12,765 to appear on earth, and they're the most diverse. 198 00:11:14,501 --> 00:11:17,737 Darwin was particularly fascinated 199 00:11:17,771 --> 00:11:19,605 by the comet orchid of Madagascar, 200 00:11:19,639 --> 00:11:23,209 a flower whose pollen is hidden at the bottom 201 00:11:23,243 --> 00:11:27,580 of a very long, thin spur. 202 00:11:27,614 --> 00:11:30,449 There can be no stronger test of an idea 203 00:11:30,484 --> 00:11:32,484 than its predictive power. 204 00:11:32,518 --> 00:11:34,219 On the basis of his theory of evolution 205 00:11:34,253 --> 00:11:35,653 through natural selection, 206 00:11:35,688 --> 00:11:38,323 Darwin speculated that somewhere 207 00:11:38,357 --> 00:11:42,127 on the island of Madagascar, there must live flying insects 208 00:11:42,161 --> 00:11:45,263 with extraordinarily lengthy tongues, 209 00:11:45,297 --> 00:11:47,132 ones long enough to reach the pollen. 210 00:11:47,166 --> 00:11:50,735 No one had ever seen such a beast there, 211 00:11:50,770 --> 00:11:52,470 but Darwin insisted 212 00:11:52,505 --> 00:11:55,807 that an animal fitting this description must exist. 213 00:11:55,841 --> 00:11:57,574 Few people at the time believed him. 214 00:11:57,609 --> 00:12:01,111 It wasn't until more than 50 years later 215 00:12:01,146 --> 00:12:03,447 that Darwin was proven right. 216 00:12:03,481 --> 00:12:09,019 In 1903, a huge hawk moth, called the Morgan's sphinx 217 00:12:09,054 --> 00:12:10,654 was discovered in Madagascar. 218 00:12:10,688 --> 00:12:14,191 Attracted by the Comet Orchid's scent, 219 00:12:14,225 --> 00:12:18,529 the moth slurps its pollen with its foot-long tongue, 220 00:12:18,563 --> 00:12:21,031 exactly as Darwin expected it would. 221 00:12:25,736 --> 00:12:29,005 It's even more amazing that the Morgan's sphinx was discovered 222 00:12:29,039 --> 00:12:31,441 when you consider that more than 90% 223 00:12:31,475 --> 00:12:34,877 of Madagascar's rain forest had been destroyed. 224 00:12:34,912 --> 00:12:37,647 In the years since Darwin's famous prediction, 225 00:12:37,681 --> 00:12:40,850 this moth species could have easily become extinct 226 00:12:40,884 --> 00:12:43,653 with all the others... 227 00:12:43,687 --> 00:12:46,889 every one of them a unique phrase of life's poetry, 228 00:12:46,924 --> 00:12:50,926 written in the atoms by eons of evolution. 229 00:12:56,566 --> 00:12:58,734 Ah, the fragrance of lilacs. 230 00:12:58,768 --> 00:13:00,502 It's one of those scents 231 00:13:00,536 --> 00:13:03,572 that triggers a whole constellation of associations, 232 00:13:03,606 --> 00:13:06,708 all those junes of long ago. 233 00:13:06,743 --> 00:13:08,510 But how does that happen? 234 00:13:08,544 --> 00:13:11,913 How does a smell prompt a movie to start running in your head? 235 00:13:11,948 --> 00:13:13,914 It's not something we can see. 236 00:13:13,949 --> 00:13:16,217 Could it be a wave of energy, like light? 237 00:13:16,251 --> 00:13:19,687 Or is it some kind of microscopic particle? 238 00:13:19,721 --> 00:13:21,389 It's actually a molecule. 239 00:13:21,423 --> 00:13:25,192 Every odor we can sense, whether it comes from burnt toast, 240 00:13:25,227 --> 00:13:28,696 gasoline, or a field of lilacs, 241 00:13:28,730 --> 00:13:30,931 is a cloud of molecules. 242 00:13:30,966 --> 00:13:34,769 These molecules have particular shapes. 243 00:13:34,771 --> 00:13:36,737 When I inhale them, 244 00:13:36,739 --> 00:13:40,740 they stimulate a particular set of receptor cells in my nose. 245 00:13:40,742 --> 00:13:44,978 An electrical signal then travels to my brain, 246 00:13:44,980 --> 00:13:47,647 which identifies the scent as lilac. 247 00:13:50,951 --> 00:13:53,086 Other scents are carried by different molecules 248 00:13:53,088 --> 00:13:55,755 with different shapes. 249 00:13:55,757 --> 00:13:59,059 But when I smell a flower or the smoke from a campfire 250 00:13:59,061 --> 00:14:00,794 or the grease from a motor gear, 251 00:14:00,796 --> 00:14:03,897 I'm often flooded with memories. 252 00:14:03,899 --> 00:14:08,367 Why is it that a simple thing such as the scent of a flower 253 00:14:08,369 --> 00:14:11,236 can trigger powerful memories? 254 00:14:14,274 --> 00:14:17,776 It has to do with the way our brains have evolved. 255 00:14:17,778 --> 00:14:20,145 Our sense of smell kicks in 256 00:14:20,147 --> 00:14:22,748 when the olfactory nerve in our brain is stimulated. 257 00:14:24,517 --> 00:14:27,886 That nerve is located very close to the amygdala, 258 00:14:27,888 --> 00:14:32,824 a structure that is integral to our experience of emotion. 259 00:14:32,826 --> 00:14:36,094 It's also very close to the Hippocampus, 260 00:14:36,096 --> 00:14:37,862 which helps us form memories. 261 00:14:40,699 --> 00:14:44,035 The network of neurons that carry the scent signal 262 00:14:44,037 --> 00:14:46,871 from my nose to my brain has been fine-tuned 263 00:14:46,873 --> 00:14:49,941 over hundreds of millions of years of evolution. 264 00:14:52,044 --> 00:14:54,345 It's a survival mechanism that can alert us 265 00:14:54,347 --> 00:14:57,214 to danger or guide us to safety. 266 00:14:59,784 --> 00:15:01,818 If you you can detect the predator 267 00:15:01,820 --> 00:15:04,855 before he's near enough to strike, 268 00:15:04,857 --> 00:15:07,190 or the fire before it traps you in the forest, 269 00:15:07,192 --> 00:15:09,359 you have a much better chance to survive 270 00:15:09,361 --> 00:15:12,195 and pass on your genes to the next generation. 271 00:15:17,969 --> 00:15:20,537 That lovely scent from this field of flowers 272 00:15:20,539 --> 00:15:23,572 sets off a unique combination of nerve signals. 273 00:15:23,574 --> 00:15:27,176 Only that exact combination can crack the safe 274 00:15:27,178 --> 00:15:30,913 where the memory of lilacs is stored inside my brain. 275 00:15:35,652 --> 00:15:37,186 Wonder who they're for. 276 00:15:38,655 --> 00:15:40,723 Maybe we'll find out later. 277 00:15:40,725 --> 00:15:44,660 But first, there's another hidden cosmos waiting for us. 278 00:16:07,103 --> 00:16:09,499 The plants are softly breathing, 279 00:16:09,534 --> 00:16:12,402 inhaling molecules of carbon dioxide 280 00:16:12,437 --> 00:16:15,138 and exhaling molecules of oxygen. 281 00:16:15,173 --> 00:16:16,639 And I'm doing the opposite. 282 00:16:16,673 --> 00:16:20,009 Unlike snowflakes and fingerprints, 283 00:16:20,043 --> 00:16:21,811 atoms or molecules of the same kind 284 00:16:21,845 --> 00:16:24,947 are utterly identical to one another. 285 00:16:24,982 --> 00:16:26,649 With every breath we take, 286 00:16:26,683 --> 00:16:29,852 we inhale as many molecules as there are stars 287 00:16:29,887 --> 00:16:32,421 in all the galaxies in the visible universe. 288 00:16:32,456 --> 00:16:35,491 And every breath we exhale is circulated through the air, 289 00:16:35,525 --> 00:16:38,027 and mixed gradually across the continents, 290 00:16:38,061 --> 00:16:41,997 it becomes available for others to breathe. 291 00:16:42,031 --> 00:16:43,365 Breathe with me. 292 00:16:54,177 --> 00:16:57,679 We all just inhaled about 100 million molecules 293 00:16:57,713 --> 00:16:59,881 that once passed through the lungs of everyone 294 00:16:59,916 --> 00:17:01,950 who ever lived before us. 295 00:17:01,984 --> 00:17:05,153 Think of it... This kind of atomic reincarnation 296 00:17:05,188 --> 00:17:07,454 is another link to our distant ancestors, 297 00:17:07,489 --> 00:17:10,991 including those who first launched us on our explorations 298 00:17:11,026 --> 00:17:13,160 of the unseen universes. 299 00:17:13,195 --> 00:17:16,630 These universes are as real as you or me, 300 00:17:16,665 --> 00:17:18,866 and they surround us. 301 00:17:23,371 --> 00:17:25,739 There was a moment when we awakened 302 00:17:25,774 --> 00:17:28,375 to a new way of thinking and seeing. 303 00:17:28,410 --> 00:17:31,846 It happened about 2,500 years ago 304 00:17:31,880 --> 00:17:33,680 on the Greek islands that lie 305 00:17:33,714 --> 00:17:36,983 between the empires of the east and west. 306 00:17:37,017 --> 00:17:41,087 There, merchants, tourists and sailors freely mingled, 307 00:17:41,121 --> 00:17:44,224 exchanging tales of great kings and gods. 308 00:17:44,258 --> 00:17:48,728 In Ionian cities and towns like Miletus, in what is now Turkey, 309 00:17:48,762 --> 00:17:50,930 the most fundamental elements 310 00:17:50,965 --> 00:17:53,867 of the way we live now first appeared. 311 00:17:57,304 --> 00:18:01,573 Here, for the first time, reenactments of aspects of life 312 00:18:01,608 --> 00:18:04,543 created and executed by professionals 313 00:18:04,577 --> 00:18:07,379 with the expectation of touching something deep 314 00:18:07,413 --> 00:18:09,181 within the hearts of the audience, 315 00:18:09,215 --> 00:18:12,084 or just making them laugh... 316 00:18:12,118 --> 00:18:16,588 The first plays, dramas and comedies, were performed. 317 00:18:19,659 --> 00:18:21,593 Government by the people. 318 00:18:21,628 --> 00:18:25,863 The first inklings, imperfect then as now, of a democracy, 319 00:18:25,898 --> 00:18:28,266 and the notion that the ordinary citizen 320 00:18:28,300 --> 00:18:30,201 might possess certain rights, 321 00:18:30,235 --> 00:18:33,804 come to us from this time and place. 322 00:18:34,707 --> 00:18:38,042 But in my view, the most revolutionary innovation of all 323 00:18:38,076 --> 00:18:41,879 to come to us from this ancient world was the idea 324 00:18:41,914 --> 00:18:45,750 that natural events were neither punishment nor reward 325 00:18:45,784 --> 00:18:47,919 from capricious gods. 326 00:18:47,953 --> 00:18:51,121 The workings of nature could be explained 327 00:18:51,155 --> 00:18:54,291 without invoking the supernatural. 328 00:18:54,325 --> 00:18:56,593 The first person to express this thought 329 00:18:56,627 --> 00:18:58,829 was a man named Thales. 330 00:18:58,863 --> 00:19:00,831 When the thunder clapped or the earth quaked, 331 00:19:00,865 --> 00:19:03,834 it was not because something you did had somehow displeased 332 00:19:03,868 --> 00:19:06,069 the very demanding gods. 333 00:19:06,103 --> 00:19:08,905 No, it was the result of natural processes 334 00:19:08,940 --> 00:19:11,441 that we were capable of understanding. 335 00:19:11,475 --> 00:19:15,177 Though none of the books he is said to have written survive, 336 00:19:15,212 --> 00:19:19,248 Thales kindled a flame that still burns to this day: 337 00:19:19,282 --> 00:19:21,317 The very idea of cosmos out of chaos, 338 00:19:21,351 --> 00:19:25,120 a universe governed by the order of natural laws 339 00:19:25,155 --> 00:19:27,122 that we can actually figure out. 340 00:19:27,757 --> 00:19:32,262 This is the epic adventure that began in the mind of Thales. 341 00:19:33,497 --> 00:19:36,832 Only a century following Thales' death, 342 00:19:36,867 --> 00:19:38,434 another genius came along. 343 00:19:38,468 --> 00:19:40,769 And he, more than any other, 344 00:19:40,804 --> 00:19:43,004 was the first to discover the existence 345 00:19:43,038 --> 00:19:46,040 of the hidden universes that surround us. 346 00:19:46,075 --> 00:19:50,145 Democritus of Abdera was a true scientist, 347 00:19:50,179 --> 00:19:53,548 a man with a passionate desire to know the cosmos 348 00:19:53,582 --> 00:19:55,350 and to have fun. 349 00:19:55,384 --> 00:19:58,686 This is the man who once said, "a life without parties 350 00:19:58,721 --> 00:20:02,123 would be like an endless road without an end." 351 00:20:02,158 --> 00:20:03,892 You mean, that's it? 352 00:20:03,926 --> 00:20:05,527 That's all there is? 353 00:20:05,561 --> 00:20:08,128 Just a bunch of atoms in a void? 354 00:20:08,163 --> 00:20:09,129 Yep. 355 00:20:10,832 --> 00:20:12,166 Well, think about it. 356 00:20:12,200 --> 00:20:13,967 The world has to be made 357 00:20:14,002 --> 00:20:17,304 of countless indivisible particles in a void. 358 00:20:17,338 --> 00:20:22,109 Otherwise, nothing could move or grow, be divided or changed. 359 00:20:23,411 --> 00:20:24,645 Without atoms 360 00:20:24,679 --> 00:20:30,362 and empty space for them to move in, 361 00:20:30,397 --> 00:20:32,797 so don't be sad, my friends. 362 00:20:32,832 --> 00:20:35,300 Just think of the infinite possibilities 363 00:20:35,334 --> 00:20:39,103 that arise from different arrangements of those atoms. 364 00:20:43,042 --> 00:20:44,576 Here's to the atoms 365 00:20:44,610 --> 00:20:48,646 in this cup and in this wine... 366 00:20:48,681 --> 00:20:51,149 And to the laughter they make possible. 367 00:20:53,185 --> 00:20:56,221 Dispersed through the Clay of the cup 368 00:20:56,255 --> 00:20:58,388 are microscopic mineral grains, 369 00:20:58,423 --> 00:21:01,058 different kinds of crystals, 370 00:21:01,092 --> 00:21:04,661 each with its own distinctive atomic architecture. 371 00:21:04,696 --> 00:21:07,164 Mineral structures are exquisite, 372 00:21:07,198 --> 00:21:10,167 but they have a limited repertoire. 373 00:21:10,201 --> 00:21:13,437 A grain of quartz is a lattice of the same three atoms 374 00:21:13,471 --> 00:21:17,307 repeated, without variation, over and over again. 375 00:21:19,210 --> 00:21:22,880 Even a relatively complex mineral lattice like topaz, 376 00:21:22,914 --> 00:21:25,348 composed of ten or so atoms, 377 00:21:25,382 --> 00:21:28,017 can only repeat the identical atomic structure 378 00:21:28,051 --> 00:21:30,052 again and again. 379 00:21:34,317 --> 00:21:36,351 Toenon, 380 00:21:36,385 --> 00:21:39,754 to free it from the lattice prison of endless repetition, 381 00:21:39,789 --> 00:21:42,224 you need an atom that can bond in all directions 382 00:21:42,258 --> 00:21:43,859 with other atoms like itself 383 00:21:43,893 --> 00:21:46,795 as well as with atoms of different kinds. 384 00:21:54,236 --> 00:21:56,737 Behold the carbon atom... 385 00:21:56,771 --> 00:21:59,940 the essential element for life on earth. 386 00:21:59,975 --> 00:22:02,810 Why? 387 00:22:02,844 --> 00:22:05,246 Carbon is special because it can bond with 388 00:22:05,280 --> 00:22:07,548 up to four other atoms at a time. 389 00:22:07,582 --> 00:22:10,317 It can connect with many different kinds of atoms, 390 00:22:10,352 --> 00:22:13,320 as well as other carbon atoms. 391 00:22:13,355 --> 00:22:14,988 It can curl into rings 392 00:22:15,022 --> 00:22:17,223 and string together into chains, 393 00:22:17,258 --> 00:22:21,661 building molecules far more complex than any crystal. 394 00:22:24,865 --> 00:22:27,767 No other atom has the same flexibility. 395 00:22:27,801 --> 00:22:30,236 Even atoms that have similar chemical properties, 396 00:22:30,271 --> 00:22:31,838 like silicon, 397 00:22:31,872 --> 00:22:33,973 can't form the amazing variety of molecules 398 00:22:34,008 --> 00:22:36,009 built on carbon. 399 00:22:36,043 --> 00:22:38,578 The carbon-based molecules we call proteins, 400 00:22:38,612 --> 00:22:40,779 the molecules of life, 401 00:22:40,814 --> 00:22:43,982 contain literally hundreds of thousands of atoms. 402 00:22:44,017 --> 00:22:47,953 Carbon atoms are the backbone of the molecules 403 00:22:47,987 --> 00:22:50,189 that make every living thing on earth, 404 00:22:50,223 --> 00:22:52,691 including us. 405 00:22:52,725 --> 00:22:55,961 That's the difference between rocks and living things. 406 00:22:57,630 --> 00:23:00,032 Life can make enormous molecules 407 00:23:00,066 --> 00:23:02,534 of stunning size and complexity, 408 00:23:02,569 --> 00:23:04,670 freeing matter to improvise, 409 00:23:04,704 --> 00:23:06,704 evolve, 410 00:23:06,738 --> 00:23:08,739 and even love. 411 00:23:41,203 --> 00:23:43,238 Take it easy, dad. 412 00:23:43,272 --> 00:23:45,674 He never actually touched her. 413 00:23:45,708 --> 00:23:47,809 In everyday life on our world, 414 00:23:47,843 --> 00:23:49,444 on the scale of atoms, 415 00:23:49,478 --> 00:23:53,348 material objects never really touch. 416 00:23:53,382 --> 00:23:56,785 Each atom has a tiny nucleus at its center, 417 00:23:56,819 --> 00:24:00,187 surrounded by an electron cloud of lines of force. 418 00:24:00,221 --> 00:24:02,690 As the atoms approach each other, 419 00:24:02,724 --> 00:24:04,658 the boy's electron clouds 420 00:24:04,693 --> 00:24:06,260 push away the girl's. 421 00:24:06,294 --> 00:24:10,431 More than 99.9% of the matter of any atom 422 00:24:10,465 --> 00:24:12,633 is concentrated in its nucleus. 423 00:24:12,667 --> 00:24:16,106 The nucleus is surrounded by an electron cloud 424 00:24:16,140 --> 00:24:18,509 which produces an invisible field of force, 425 00:24:18,543 --> 00:24:20,811 and acts like a shock absorber. 426 00:24:20,845 --> 00:24:23,480 The configuration of the electron cloud 427 00:24:23,514 --> 00:24:25,481 determines the nature of an element. 428 00:24:25,516 --> 00:24:28,150 In the ordinary course of things here on earth, 429 00:24:28,185 --> 00:24:30,052 the nuclei never touch. 430 00:24:30,087 --> 00:24:32,154 We have a sensation of touching, 431 00:24:32,189 --> 00:24:34,790 but that's really just our invisible force fields 432 00:24:34,825 --> 00:24:37,760 overlapping and repelling each other. 433 00:24:53,543 --> 00:24:55,977 The nucleus is very small 434 00:24:56,012 --> 00:24:57,646 compared to the rest of the atom. 435 00:24:57,680 --> 00:25:01,683 If an atom were the size of this cathedral, 436 00:25:01,717 --> 00:25:05,954 its nucleus would be the size of that mote of dust. 437 00:25:08,724 --> 00:25:12,928 An atom is mostly empty space. 438 00:25:12,962 --> 00:25:15,664 To understand the nature of matter, 439 00:25:15,698 --> 00:25:17,665 we have to go deeper still, 440 00:25:17,699 --> 00:25:20,701 to a place 100,000 times smaller than the atom: 441 00:25:20,735 --> 00:25:22,736 Its nucleus. 442 00:25:25,907 --> 00:25:27,675 The simplest and most plentiful atom 443 00:25:27,709 --> 00:25:30,344 in the cosmos is hydrogen. 444 00:25:30,378 --> 00:25:32,580 Its nucleus is a single proton, 445 00:25:32,614 --> 00:25:35,616 which makes hydrogen element number one. 446 00:25:35,650 --> 00:25:37,451 The clouds that surround it 447 00:25:37,485 --> 00:25:39,854 are the realms where the atom's lone electron 448 00:25:39,888 --> 00:25:42,422 is permitted to roam. 449 00:25:42,456 --> 00:25:45,692 What happens when you have a nucleus with two protons? 450 00:25:45,726 --> 00:25:47,360 Protons repel each other. 451 00:25:47,394 --> 00:25:49,729 In order to hold them together in a nucleus, 452 00:25:49,763 --> 00:25:52,932 you need other particles called neutrons. 453 00:25:52,967 --> 00:25:55,535 Their job is to keep the protons 454 00:25:55,569 --> 00:25:56,970 from getting out of line. 455 00:25:57,004 --> 00:25:59,105 They overwhelm the protons 456 00:25:59,139 --> 00:26:01,975 with their strong attractive nuclear force. 457 00:26:02,009 --> 00:26:05,245 A nucleus with two protons is element number two, 458 00:26:05,279 --> 00:26:07,913 otherwise known as helium. 459 00:26:07,947 --> 00:26:10,949 A nucleus with six protons is element number six, 460 00:26:10,984 --> 00:26:12,918 which is carbon, 461 00:26:12,952 --> 00:26:16,054 the fundamental building block of life. 462 00:26:16,089 --> 00:26:19,224 The nucleus of a gold atom has 79 protons. 463 00:26:19,259 --> 00:26:21,260 They attract 79 electrons 464 00:26:21,294 --> 00:26:23,095 in clouds around it. 465 00:26:23,129 --> 00:26:25,397 The way light interacts with those electrons 466 00:26:25,431 --> 00:26:27,997 is what makes gold glitter. 467 00:26:28,031 --> 00:26:30,966 Every additional proton in the nucleus 468 00:26:31,001 --> 00:26:34,269 requires enough neutrons to bind them together... 469 00:26:34,303 --> 00:26:35,937 Up to a point. 470 00:26:35,971 --> 00:26:38,172 There's an upper limit to the number of neutrons 471 00:26:38,174 --> 00:26:39,941 you can stuff into a nucleus 472 00:26:39,943 --> 00:26:41,709 before it becomes unstable. 473 00:26:41,711 --> 00:26:43,878 I know a place 474 00:26:43,880 --> 00:26:45,947 where the nuclei of different atoms 475 00:26:45,949 --> 00:26:47,949 actually do touch each other. 476 00:27:08,002 --> 00:27:10,504 The sun looks like a solid object, 477 00:27:10,506 --> 00:27:12,706 but it's not. 478 00:27:12,708 --> 00:27:15,642 It's so hot that all its atoms 479 00:27:15,644 --> 00:27:17,544 are always in their gaseous state. 480 00:27:17,546 --> 00:27:18,979 The bonds that join atoms 481 00:27:18,981 --> 00:27:20,747 to make solids and liquids on earth 482 00:27:20,749 --> 00:27:22,649 are not strong enough to withstand 483 00:27:22,651 --> 00:27:25,618 the heat of the broiling sun. 484 00:27:25,620 --> 00:27:28,487 Those arcing streams of incandescent gas 485 00:27:28,489 --> 00:27:30,690 that dwarf the earth 486 00:27:30,692 --> 00:27:32,825 are guided by magnetic lines of force 487 00:27:32,827 --> 00:27:35,895 that emanate from below the surface of the sun. 488 00:27:35,897 --> 00:27:38,431 Why is the sun so hot? 489 00:27:38,433 --> 00:27:40,733 Because its own stupendous gravity 490 00:27:40,735 --> 00:27:43,169 is squeezing its atoms together. 491 00:27:45,539 --> 00:27:48,174 The energy of gravity is being transformed 492 00:27:48,176 --> 00:27:50,308 into the energy of moving atoms. 493 00:27:50,310 --> 00:27:53,011 That's what heat is. 494 00:27:53,013 --> 00:27:54,880 The deeper we go into the sun, 495 00:27:54,882 --> 00:27:56,681 the greater the squeezing 496 00:27:56,683 --> 00:27:58,950 and the higher the temperature. 497 00:27:58,952 --> 00:28:00,519 In the heart of the sun, 498 00:28:00,521 --> 00:28:02,354 the atoms are moving so fast 499 00:28:02,356 --> 00:28:04,723 that when they collide, they fuse. 500 00:28:04,725 --> 00:28:08,360 Their nuclei touch. 501 00:28:08,362 --> 00:28:11,796 The sun is a nuclear fusion reactor, 502 00:28:11,798 --> 00:28:14,065 held together by its own gravity. 503 00:28:14,067 --> 00:28:17,401 It's balanced between the inward pull of gravity 504 00:28:17,403 --> 00:28:20,037 and the outward push of its hot gases. 505 00:28:23,975 --> 00:28:27,278 That balance has lasted billions of years, 506 00:28:27,312 --> 00:28:29,246 providing stability that made possible 507 00:28:29,281 --> 00:28:30,781 the evolution of life on earth. 508 00:28:30,815 --> 00:28:33,217 In the sun's core, 509 00:28:33,251 --> 00:28:35,119 the fusion of hydrogen into helium 510 00:28:35,153 --> 00:28:38,289 releases nuclear energy in the form of photons. 511 00:28:38,323 --> 00:28:39,957 These particles of light 512 00:28:39,991 --> 00:28:41,891 slowly work their way to the surface, 513 00:28:41,926 --> 00:28:43,626 where they're seen as sunlight. 514 00:28:43,661 --> 00:28:47,564 Helium is the ash of the sun's nuclear furnace. 515 00:28:49,567 --> 00:28:51,401 The sun is a medium-sized star. 516 00:28:51,435 --> 00:28:55,038 Its core is only a lukewarm ten million degrees... 517 00:28:55,072 --> 00:28:56,372 hot enough to fuse hydrogen, 518 00:28:56,407 --> 00:28:58,374 but too cold to fuse helium. 519 00:28:58,409 --> 00:29:00,777 There are many stars in the galaxy 520 00:29:00,811 --> 00:29:02,378 that get much hotter, 521 00:29:02,413 --> 00:29:03,913 because they're more massive 522 00:29:03,948 --> 00:29:05,481 and have more gravity. 523 00:29:05,516 --> 00:29:08,650 Such stars fuse helium into heavier elements, 524 00:29:08,685 --> 00:29:10,619 like carbon and oxygen. 525 00:29:10,653 --> 00:29:12,554 In their old age, 526 00:29:12,589 --> 00:29:15,257 they gently diffuse these elements into space. 527 00:29:17,660 --> 00:29:19,828 Other stars, more massive yet, 528 00:29:19,863 --> 00:29:22,130 live fast and die young 529 00:29:22,165 --> 00:29:24,132 in cataclysmic supernova explosions. 530 00:29:24,167 --> 00:29:27,336 In our galaxy, such stars go supernova 531 00:29:27,370 --> 00:29:28,770 about once a century. 532 00:29:31,207 --> 00:29:33,841 These explosions are far hotter than the core of the sun... 533 00:29:33,876 --> 00:29:36,777 hot enough to transform elements like iron 534 00:29:36,812 --> 00:29:39,146 into all the heavier ones 535 00:29:39,181 --> 00:29:42,350 and spew them into space. 536 00:29:42,384 --> 00:29:44,252 The large magellanic cloud 537 00:29:44,286 --> 00:29:46,454 is a neighboring galaxy of our milky way. 538 00:29:46,488 --> 00:29:49,123 It's visible in the skies of the Southern hemisphere. 539 00:29:50,225 --> 00:29:51,792 When a supernova explodes, 540 00:29:51,827 --> 00:29:53,361 its brightness rivals 541 00:29:53,395 --> 00:29:56,731 that of its entire galaxy. 542 00:30:06,474 --> 00:30:09,609 But all that light is only about one percent 543 00:30:09,644 --> 00:30:12,279 of the energy liberated in the explosion. 544 00:30:12,313 --> 00:30:15,382 The rest of the energy is carried off by the most common 545 00:30:15,416 --> 00:30:17,717 and the most mysterious particles in the cosmos. 546 00:30:17,752 --> 00:30:21,121 There are trillions of them passing through you right now, 547 00:30:21,155 --> 00:30:23,657 and yet tracking down even one of them 548 00:30:23,691 --> 00:30:27,326 will take us to one of the strangest places on earth. 549 00:30:36,996 --> 00:30:39,064 Stalking the wild neutrino 550 00:30:39,098 --> 00:30:40,899 is the rarest of sport. 551 00:30:40,933 --> 00:30:43,468 The lengths one must go to track them down 552 00:30:43,503 --> 00:30:45,237 is nothing short of astonishing. 553 00:30:45,271 --> 00:30:48,907 Welcome to Super Kamiokande, 554 00:30:48,941 --> 00:30:52,743 the subterranean Japanese neutrino detection chamber. 555 00:30:52,777 --> 00:30:55,913 We're more than a half mile beneath earth's surface. 556 00:30:55,947 --> 00:30:58,182 You might ask, "well, who in their right mind 557 00:30:58,216 --> 00:31:01,418 would bury an astronomical observatory so far underground?" 558 00:31:01,453 --> 00:31:04,989 Those who hunt the most elusive prey in the cosmos: 559 00:31:05,023 --> 00:31:06,991 The neutrino. 560 00:31:07,025 --> 00:31:08,993 This enormous array of light detectors 561 00:31:09,027 --> 00:31:12,062 surrounding 50,000 tons of distilled water 562 00:31:12,097 --> 00:31:15,566 is a trap designed to catch neutrinos only. 563 00:31:15,600 --> 00:31:18,001 Other particles, such as cosmic rays... 564 00:31:18,035 --> 00:31:21,004 mostly protons and electrons that rain down from space... 565 00:31:21,038 --> 00:31:23,606 cannot get through all that rock above us. 566 00:31:23,641 --> 00:31:27,010 But matter poses no obstacle to a neutrino. 567 00:31:27,044 --> 00:31:31,047 A neutrino could pass through 100 light-years of steel 568 00:31:31,081 --> 00:31:33,516 without even slowing down. 569 00:31:33,551 --> 00:31:36,252 Neutrinos hardly interact with matter at all. 570 00:31:36,287 --> 00:31:37,954 That's why you need so much of it 571 00:31:37,988 --> 00:31:39,556 to catch even one of them. 572 00:31:39,590 --> 00:31:41,624 On those rare occasions when a neutrino 573 00:31:41,659 --> 00:31:44,393 actually does collide with a particle of ordinary matter, 574 00:31:44,427 --> 00:31:48,597 it produces a ghostly, ring-shaped flash of light. 575 00:31:48,631 --> 00:31:51,300 We're lying in wait 576 00:31:51,334 --> 00:31:54,903 for a particle that weighs next to nothing. 577 00:31:54,938 --> 00:31:56,905 Even the miniscule electron 578 00:31:56,940 --> 00:31:59,908 has more than a million times its mass... 579 00:31:59,943 --> 00:32:01,610 There! 580 00:32:01,644 --> 00:32:03,812 When the supernova in the large magellanic cloud 581 00:32:03,847 --> 00:32:06,114 blew its top in 1987, 582 00:32:06,149 --> 00:32:09,050 this is what it would have looked like in here. 583 00:32:09,084 --> 00:32:11,486 Now remember, the large magellanic cloud 584 00:32:11,520 --> 00:32:12,820 is in our Southern hemisphere, 585 00:32:12,855 --> 00:32:14,422 so the neutrinos didn't come through 586 00:32:14,456 --> 00:32:16,057 that half-mile of rock above us, 587 00:32:16,091 --> 00:32:18,659 they had to pass through the thousands of miles 588 00:32:18,694 --> 00:32:21,496 of rock and iron below us to reach this detector. 589 00:32:21,530 --> 00:32:24,165 But the coolest thing was that those neutrinos 590 00:32:24,199 --> 00:32:26,801 hit earth three hours before 591 00:32:26,835 --> 00:32:28,836 the light from the supernova did. 592 00:32:28,871 --> 00:32:31,072 If nothing can travel faster than light, 593 00:32:31,106 --> 00:32:33,508 how could that possibly be? 594 00:32:39,113 --> 00:32:41,982 This is a dead star walking. 595 00:32:42,016 --> 00:32:45,485 It may look normal, but deep within it 596 00:32:45,520 --> 00:32:47,954 something cataclysmic is happening. 597 00:32:47,989 --> 00:32:50,323 This blue super giant star 598 00:32:50,358 --> 00:32:54,795 has already begun to explode inside. 599 00:32:58,399 --> 00:33:01,967 Like rats deserting a sinking ship, the neutrinos 600 00:33:02,002 --> 00:33:04,470 produced in the heart of the exploding star 601 00:33:04,504 --> 00:33:07,039 race outward at near the speed of light, 602 00:33:07,073 --> 00:33:09,442 through overlying mass 603 00:33:09,476 --> 00:33:11,043 in only a few seconds. 604 00:33:11,077 --> 00:33:13,279 But the shock wave of the exploding gas 605 00:33:13,313 --> 00:33:16,315 plods along from the center of the star 606 00:33:16,349 --> 00:33:18,951 at 1/10,000 the speed of light 607 00:33:18,985 --> 00:33:21,187 until it finally reaches 608 00:33:21,221 --> 00:33:22,655 the star's surface, 609 00:33:22,689 --> 00:33:26,424 turning it into supernova 1987a. 610 00:33:32,531 --> 00:33:34,199 It took hours for the explosion 611 00:33:34,233 --> 00:33:36,801 to reach the surface of the star and blow it wide open, 612 00:33:36,836 --> 00:33:38,636 exposing the super hot core. 613 00:33:38,671 --> 00:33:41,706 The neutrinos had an insurmountable head start. 614 00:33:41,740 --> 00:33:44,542 That's why the flash of light arrived on earth 615 00:33:44,577 --> 00:33:47,545 so much later than the shower of neutrinos. 616 00:33:47,580 --> 00:33:51,015 Before anyone had ever snared the wild neutrino, 617 00:33:51,050 --> 00:33:54,918 it existed in the mind of a theoretical physicist. 618 00:33:54,953 --> 00:33:57,988 Just as Charles Darwin knew 619 00:33:58,022 --> 00:34:00,591 there must be an extremely long-nosed creature 620 00:34:00,625 --> 00:34:02,593 flying around somewhere in Madagascar, 621 00:34:02,627 --> 00:34:06,463 a 20th-century physicist named Wolfgang Pauli... 622 00:34:09,467 --> 00:34:11,401 was desperately seeking a particle 623 00:34:11,436 --> 00:34:13,704 to rescue one of the pillars of modern physics, 624 00:34:13,738 --> 00:34:17,074 the law of the conservation of energy. 625 00:34:25,916 --> 00:34:27,950 So why didn't I flinch? 626 00:34:27,985 --> 00:34:30,253 Because the laws of science differ fundamentally 627 00:34:30,287 --> 00:34:32,088 from those of other human endeavors. 628 00:34:32,122 --> 00:34:35,625 In order for an idea to become a scientific law, 629 00:34:35,659 --> 00:34:37,460 it has to unbreakable. 630 00:34:37,494 --> 00:34:40,229 That's why I was willing to bet this face 631 00:34:40,264 --> 00:34:43,131 on the laws of conservation of energy. 632 00:34:43,166 --> 00:34:45,567 Now, if you try this at home, 633 00:34:45,601 --> 00:34:48,570 take care not to give the cannonball a push. 634 00:34:48,604 --> 00:34:50,205 That's adding energy, 635 00:34:50,239 --> 00:34:52,774 and the ball will surely come back and do some damage. 636 00:34:52,809 --> 00:34:55,811 You just have to let it go, like this. 637 00:34:57,013 --> 00:34:58,313 By lifting the ball, 638 00:34:58,347 --> 00:35:00,048 you give it gravitational energy, 639 00:35:00,082 --> 00:35:03,051 which is the potential to fall and accelerate. 640 00:35:03,085 --> 00:35:04,619 The cannonball is going fastest 641 00:35:04,654 --> 00:35:06,288 when it's at the bottom of its arc, 642 00:35:06,322 --> 00:35:07,956 and at that moment, 643 00:35:07,990 --> 00:35:10,157 it's converted all of its gravitational energy 644 00:35:10,192 --> 00:35:12,226 to the energy of motion. 645 00:35:12,260 --> 00:35:14,929 As it swings, the cannonball is constantly exchanging 646 00:35:14,963 --> 00:35:17,164 one of these two kinds of energy for the other, 647 00:35:17,199 --> 00:35:20,401 but the total amount of energy remains constant. 648 00:35:20,435 --> 00:35:23,771 That's an example of the law of conservation of energy. 649 00:35:23,805 --> 00:35:26,240 Once the cannonball is released, 650 00:35:26,274 --> 00:35:29,310 it can never gain more energy than it had to begin with. 651 00:35:29,344 --> 00:35:32,646 It has no way to fly up and break my nose. 652 00:35:32,681 --> 00:35:36,649 The energy accounting books are always strictly balanced. 653 00:35:36,684 --> 00:35:39,018 There's no such thing as cheating. 654 00:35:39,053 --> 00:35:40,854 So in the 20th century, 655 00:35:40,888 --> 00:35:44,257 when physicists first calculated the energy of atoms precisely, 656 00:35:44,291 --> 00:35:45,525 they were startled to discover 657 00:35:45,559 --> 00:35:48,061 an apparent violation of this law. 658 00:35:50,164 --> 00:35:52,632 They found that in some radioactive atoms, 659 00:35:52,666 --> 00:35:56,035 the nucleus can spontaneously eject an electron. 660 00:35:56,070 --> 00:35:59,606 This transforms the atom into a different element. 661 00:35:59,640 --> 00:36:02,174 The physicists were mystified. 662 00:36:02,208 --> 00:36:04,276 The energy of the escaped electron 663 00:36:04,310 --> 00:36:06,278 plus that of the new element 664 00:36:06,312 --> 00:36:09,615 adds up to less than the energy in the original nucleus. 665 00:36:09,649 --> 00:36:11,517 But the law says, 666 00:36:11,551 --> 00:36:14,453 "thou shall not destroy or create energy." 667 00:36:14,487 --> 00:36:17,322 So where did the missing energy go? 668 00:36:17,357 --> 00:36:19,491 In 1930... 669 00:36:19,526 --> 00:36:22,061 Wolfgang Pauli predicted 670 00:36:22,095 --> 00:36:24,196 there must be an undiscovered particle, 671 00:36:24,230 --> 00:36:26,664 one that makes off with the missing energy. 672 00:36:26,698 --> 00:36:29,467 At the time, Pauli lamented 673 00:36:29,501 --> 00:36:32,904 that such a phantom particle might be so minute, 674 00:36:32,938 --> 00:36:34,839 swift and evasive 675 00:36:34,873 --> 00:36:37,909 as to forever defy detection. 676 00:36:37,943 --> 00:36:41,345 But that was a rare failure of his imagination 677 00:36:41,380 --> 00:36:43,548 because science is always searching 678 00:36:43,582 --> 00:36:45,416 for a way to go deeper still. 679 00:36:45,451 --> 00:36:47,351 A generation later, 680 00:36:47,386 --> 00:36:49,721 Pauli's neutrinos were actually detected for the first time 681 00:36:49,755 --> 00:36:52,322 in radiation from a nuclear reactor. 682 00:36:52,356 --> 00:36:56,259 And we've been finding them, with difficulty, ever since. 683 00:36:57,724 --> 00:36:58,980 There are scientists today 684 00:36:59,015 --> 00:37:02,215 who are trying to find a way to ride those neutrinos 685 00:37:02,250 --> 00:37:05,752 all the way back to the beginning of time. 686 00:37:07,255 --> 00:37:09,122 We'll go as far as they have gone 687 00:37:09,157 --> 00:37:13,093 to come up against the wall of forever. 688 00:37:22,539 --> 00:37:25,274 The wall of forever is nothing new. 689 00:37:25,308 --> 00:37:27,242 Our ancestors came up against it 690 00:37:27,277 --> 00:37:30,379 almost as soon as they first started imagining it. 691 00:37:30,413 --> 00:37:35,184 A million dawns ago, in the 13th century bc, 692 00:37:35,218 --> 00:37:38,721 the Egyptian this temple at Abu Simbel 693 00:37:38,755 --> 00:37:40,789 to honor the Pharaoh Ramses II, 694 00:37:40,824 --> 00:37:44,026 depicted here in four colossal statues. 695 00:37:44,060 --> 00:37:46,961 Reigning even above even this mighty king 696 00:37:46,996 --> 00:37:49,964 is the falcon-headed Ra-Harakhti, 697 00:37:49,999 --> 00:37:52,233 God of the sun. 698 00:37:56,672 --> 00:37:58,773 The temple was designed 699 00:37:58,807 --> 00:38:00,541 so that the light from the rising sun 700 00:38:00,576 --> 00:38:04,879 could only enter the sanctuary on two days every year. 701 00:38:04,914 --> 00:38:07,916 As the rays enter the temple, 702 00:38:07,950 --> 00:38:09,884 they burnish the statues of the gods 703 00:38:09,919 --> 00:38:11,551 with their golden light 704 00:38:11,586 --> 00:38:15,556 before penetrating the sanctuary. 705 00:38:15,590 --> 00:38:19,560 Even then, one God remains in shadow. 706 00:38:19,594 --> 00:38:22,062 Ptah, lord of creation, 707 00:38:22,096 --> 00:38:24,298 as if the origin of the universe 708 00:38:24,332 --> 00:38:27,167 must forever be concealed. 709 00:38:30,872 --> 00:38:33,674 Feel the sun on your face. 710 00:38:33,708 --> 00:38:36,275 The energy that warms you 711 00:38:36,310 --> 00:38:39,445 began its journey some ten million years ago 712 00:38:39,479 --> 00:38:41,581 in the heart of the sun. 713 00:38:41,615 --> 00:38:44,650 Unlike neutrinos, 714 00:38:44,685 --> 00:38:46,485 the photons needed 715 00:38:46,520 --> 00:38:49,488 that long to work their way out from the core to the surface. 716 00:38:49,523 --> 00:38:51,524 Why? 717 00:38:51,558 --> 00:38:54,460 Because they were colliding billions of times per second 718 00:38:54,494 --> 00:38:56,762 with the sun's atoms, every collision 719 00:38:56,797 --> 00:38:59,765 sending them off in a random direction. 720 00:38:59,800 --> 00:39:01,766 But once they finally reached the surface, 721 00:39:01,801 --> 00:39:03,201 they were free 722 00:39:03,236 --> 00:39:05,937 to dash nonstop, at the speed of light, 723 00:39:05,972 --> 00:39:08,173 in a mere eight minutes and 20 seconds 724 00:39:08,207 --> 00:39:09,975 from the sun to you. 725 00:39:11,711 --> 00:39:14,846 Ten-million-year-old light on your face. 726 00:39:17,216 --> 00:39:19,484 What was happening 727 00:39:19,519 --> 00:39:22,854 when that light left the heart of the sun? 728 00:39:27,759 --> 00:39:30,794 The cosmic calendar compresses 729 00:39:30,829 --> 00:39:33,631 the entire 13.8 billion year history 730 00:39:33,665 --> 00:39:35,733 of the universe into a single year. 731 00:39:35,767 --> 00:39:39,303 Every month represents about a billion years. 732 00:39:39,337 --> 00:39:42,206 Every day, about 40 million years. 733 00:39:42,240 --> 00:39:45,476 The universe is so old that, on the cosmic calendar, 734 00:39:45,510 --> 00:39:49,246 ten million years ago only takes us back as far as... 735 00:39:49,281 --> 00:39:52,883 6:00 P.M. on the last evening 736 00:39:52,918 --> 00:39:55,752 of the last day of the year. 737 00:39:55,786 --> 00:39:57,353 And what about us? 738 00:39:57,388 --> 00:39:59,222 Humans had yet to evolve. 739 00:39:59,256 --> 00:40:00,990 Ten million years ago, 740 00:40:01,025 --> 00:40:03,426 our ancestors were anthropoid apes, 741 00:40:03,460 --> 00:40:05,361 swinging through the trees of Africa. 742 00:40:05,396 --> 00:40:08,865 To us, ten million years seems like a long time, 743 00:40:08,899 --> 00:40:11,267 but it's only the length of an afternoon 744 00:40:11,302 --> 00:40:13,770 on the timescale of the cosmos. 745 00:40:17,107 --> 00:40:19,708 The sun began fusing hydrogen 746 00:40:19,742 --> 00:40:22,044 4,500 million years ago... 747 00:40:22,078 --> 00:40:25,781 August 31 on the cosmic calendar. 748 00:40:25,815 --> 00:40:27,850 Our milky way galaxy 749 00:40:27,884 --> 00:40:30,953 is about 10,000 million years old. 750 00:40:30,987 --> 00:40:36,058 The first galaxies formed about a few billion years earlier. 751 00:40:36,092 --> 00:40:40,028 Something keeps me from going any further back in time. 752 00:40:40,063 --> 00:40:42,064 What is this? 753 00:40:45,734 --> 00:40:47,602 It's the nature of light and time. 754 00:40:47,636 --> 00:40:50,805 Because light travels at a finite speed, 755 00:40:50,839 --> 00:40:53,107 to look across space 756 00:40:53,142 --> 00:40:55,810 is to look back in time. 757 00:40:58,747 --> 00:41:00,882 So the farther we see, 758 00:41:00,916 --> 00:41:03,718 the older the light. 759 00:41:03,752 --> 00:41:06,554 This is as far back in the history of the cosmos 760 00:41:06,588 --> 00:41:08,556 as we can see with light. 761 00:41:08,590 --> 00:41:10,991 It's a baby picture of universe, 762 00:41:11,025 --> 00:41:14,094 when it was only 380,000 years old. 763 00:41:14,128 --> 00:41:17,898 That's 15 minutes into January 1 764 00:41:17,932 --> 00:41:19,766 on the cosmic calendar. 765 00:41:19,801 --> 00:41:22,936 If we look as far as we can see in any direction 766 00:41:22,970 --> 00:41:24,938 using microwave telescopes, 767 00:41:24,972 --> 00:41:26,406 this is what we see, 768 00:41:26,441 --> 00:41:29,743 the glow left over from the Big Bang. 769 00:41:29,777 --> 00:41:31,745 Imagine that all the matter and energy 770 00:41:31,779 --> 00:41:33,647 of the observable universe 771 00:41:33,681 --> 00:41:35,415 was concentrated into something 772 00:41:35,450 --> 00:41:37,950 no larger than this. 773 00:41:37,984 --> 00:41:41,854 That's the size of the universe 774 00:41:41,888 --> 00:41:44,256 when it was a trillionth of a trillionth 775 00:41:44,291 --> 00:41:47,259 of a trillionth of a second old. 776 00:41:47,294 --> 00:41:50,830 All the matter and energy of the hundred billion galaxies 777 00:41:50,864 --> 00:41:53,933 now splayed out across the billions of light-years 778 00:41:53,967 --> 00:41:55,935 were once pent up 779 00:41:55,969 --> 00:41:58,304 in something the size of a marble. 780 00:41:58,338 --> 00:42:00,372 Can you imagine how tightly packed 781 00:42:00,407 --> 00:42:02,273 that marble must have been? 782 00:42:02,308 --> 00:42:05,143 Far too dense for any kind of light to move through it, 783 00:42:05,177 --> 00:42:08,947 but no obstacle for the likes of neutrinos. 784 00:42:08,981 --> 00:42:11,850 The big bang must have produced stupendous numbers of neutrinos, 785 00:42:11,884 --> 00:42:13,451 which flew unhindered 786 00:42:13,486 --> 00:42:15,553 through that inconceivable crush of matter. 787 00:42:15,588 --> 00:42:18,790 The very thing that makes them almost impossible to detect 788 00:42:18,824 --> 00:42:22,894 is what allows neutrinos to sail through the curtain 789 00:42:22,928 --> 00:42:25,563 that conceals the beginning of time. 790 00:42:25,598 --> 00:42:27,164 Where are they now? 791 00:42:27,198 --> 00:42:28,732 They are here, they're there, 792 00:42:28,767 --> 00:42:30,968 everywhere throughout the universe. 793 00:42:31,002 --> 00:42:33,837 Neutrinos from creation are within you. 794 00:42:34,906 --> 00:42:37,141 From a marble... 795 00:42:37,175 --> 00:42:39,176 To the cosmos. 796 00:42:49,921 --> 00:42:53,222 This is the road that Thales and Democritus put us on 797 00:42:53,257 --> 00:42:56,025 some 2,500 years ago... 798 00:42:56,059 --> 00:42:58,094 a road of endless searching, 799 00:42:58,128 --> 00:43:01,431 a relentless, systematic hunt for new worlds 800 00:43:01,465 --> 00:43:04,100 and an ever-deepening understanding of nature. 801 00:43:05,569 --> 00:43:08,438 Who among you will pick up that torch 802 00:43:08,472 --> 00:43:12,075 and take us down that next stretch of road?