WEBVTT 00:00:00.085 --> 00:00:02.646 Equipped with his five senses 00:00:02.722 --> 00:00:05.590 man explores the universe around him 00:00:05.660 --> 00:00:07.992 and calls the adventure Science. 00:01:09.375 --> 00:01:12.402 Things around us aren't always what they seem. 00:01:29.167 --> 00:01:33.400 ln the everyday world, we use a simple scale, ourselves 00:01:33.506 --> 00:01:36.271 to know what's small and what's large. 00:01:47.057 --> 00:01:49.549 But what about the worlds that lie beyond? 00:01:52.063 --> 00:01:55.625 What is truly large and truly small? 00:02:04.045 --> 00:02:07.379 To explore, to observe 00:02:07.783 --> 00:02:11.220 to understand the wider world we call the universe: 00:02:12.322 --> 00:02:15.121 This is one of the great human adventures. 00:02:30.278 --> 00:02:35.081 As we look out at the distant horizon, we may ask ourselves 00:02:35.686 --> 00:02:38.952 what is our true place in the universe? 00:02:42.528 --> 00:02:44.894 We are all travelers 00:02:44.965 --> 00:02:47.991 on an unending voyage of discovery. 00:03:27.986 --> 00:03:32.014 More than 25 centuries ago, among the Greek lslands 00:03:32.091 --> 00:03:36.153 here at the vibrant crossroads of Africa, Asia and Europe 00:03:36.564 --> 00:03:41.060 philosophers devised rational theories about the world around them. 00:03:44.875 --> 00:03:47.845 The wondrous waves and foams of nature, they said 00:03:48.179 --> 00:03:49.771 could be understood. 00:04:20.353 --> 00:04:25.054 One Greek thinker suggested that the Earth moved around the sun. 00:04:28.597 --> 00:04:32.831 Another taught that everything, the work of man and nature 00:04:33.137 --> 00:04:36.665 was made of particles too small to see. 00:04:41.414 --> 00:04:44.384 Others estimated the sizes of the Earth and the moon 00:04:44.451 --> 00:04:47.546 and the distances between them, and reasoned 00:04:47.622 --> 00:04:49.283 both were spheres. 00:04:52.428 --> 00:04:56.593 But it would be centuries before we had the tools to extend our vision 00:04:56.800 --> 00:04:59.827 and confirm the wisdom of these early thinkers. 00:05:01.774 --> 00:05:03.435 ln the meantime 00:05:03.509 --> 00:05:07.641 people around the world gazed on the stars and gave them names. 00:05:08.683 --> 00:05:13.383 Most assumed the Earth was the center of an unchanging universe. 00:05:47.866 --> 00:05:49.698 Two thousand years passed 00:05:49.769 --> 00:05:53.570 before a revolutionary breakthrough was made by a mathematics professor 00:05:53.641 --> 00:05:56.941 in the ancient, maritime republic of Venice. 00:05:58.113 --> 00:06:01.572 ln 1609, Galileo Galilei 00:06:01.817 --> 00:06:05.811 demonstrated an instrument that would soon be called a telescope. 00:06:09.995 --> 00:06:11.860 From the tallest bell towers 00:06:11.930 --> 00:06:14.559 he showed the device could spot approaching ships 00:06:14.634 --> 00:06:17.866 hours before their sails were visible to the naked eye. 00:06:19.707 --> 00:06:22.973 Later, when he aimed his telescope at the night sky 00:06:23.245 --> 00:06:26.682 Galileo discovered that the moon was a world of mountains. 00:06:27.351 --> 00:06:29.319 Jupiter had its own moons 00:06:29.453 --> 00:06:32.651 and the Milky Way was a band of countless stars. 00:06:38.065 --> 00:06:40.932 Our own cosmic voyage begins here 00:06:41.135 --> 00:06:44.867 in the center of Galileo's Venice, St. Mark's Square. 00:06:50.780 --> 00:06:54.478 Since the universe is a big place, we could easily get lost 00:06:55.087 --> 00:06:58.580 so we'll need signposts to give us a sense of scale. 00:07:01.627 --> 00:07:04.654 The acrobats' ring is one meter wide. 00:07:08.002 --> 00:07:11.939 The crowd is ten times wider, ten meters across. 00:07:12.007 --> 00:07:14.238 Larger by one power of ten. 00:07:18.583 --> 00:07:21.815 Now, with every step, every ring 00:07:22.287 --> 00:07:25.257 we travel ten times farther from Venice 00:07:25.492 --> 00:07:28.690 and our view of the universe is ten times wider. 00:07:32.100 --> 00:07:34.934 The 100-meter ring surrounds St. Mark's 00:07:35.338 --> 00:07:39.275 and 1,000 meters, one kilometer, the city's center. 00:07:41.513 --> 00:07:45.974 As our speed increases, four steps, four powers of ten 00:07:46.152 --> 00:07:51.182 reveal all the islands of Venice, the Adriatic Sea and Northern ltaly. 00:07:58.568 --> 00:08:03.302 Six steps take in Europe from Germany across to the Balkans. 00:08:07.546 --> 00:08:10.414 And soon, we can see the entire planet. 00:08:11.050 --> 00:08:12.848 Our home in space. 00:08:24.634 --> 00:08:26.830 Eight steps on our outward journey 00:08:26.938 --> 00:08:31.205 eight powers of ten, and we pass the farthest reaches of human travel: 00:08:32.511 --> 00:08:33.672 The moon. 00:08:59.512 --> 00:09:02.949 lf we visualize the paths that the nine planets take 00:09:03.017 --> 00:09:05.145 in their orbits around the sun 00:09:06.455 --> 00:09:09.289 at 13 steps from St. Mark's Square 00:09:09.826 --> 00:09:13.263 the entire solar system comes into view. 00:09:22.576 --> 00:09:26.536 And with 15 steps, 15 powers of ten 00:09:27.248 --> 00:09:30.878 we can see our sun is just another star. 00:09:31.388 --> 00:09:35.155 From here on, our voyage will be measured in light-years. 00:09:35.760 --> 00:09:38.992 The distance light travels in an entire year. 00:09:41.300 --> 00:09:45.102 Only now do we fly past our nearest neighbor stars 00:09:45.706 --> 00:09:48.300 almost five light-years away. 00:09:49.911 --> 00:09:53.177 The same journey at the speed of today's spacecraft 00:09:53.382 --> 00:09:56.580 would last 100,000 years. 00:10:03.729 --> 00:10:06.221 As we cross the perpetual night 00:10:06.299 --> 00:10:09.701 our voyage takes us up and out of our sun's neighborhood 00:10:09.837 --> 00:10:13.035 near the edge of a great pinwheel of stars. 00:10:35.636 --> 00:10:38.367 The Milky Way is actually a spiral galaxy 00:10:38.807 --> 00:10:43.268 and our own sun is just one of a hundred billion stars in it. 00:10:44.515 --> 00:10:48.247 At this immense scale, 23 powers of ten 00:10:48.587 --> 00:10:51.284 each shining light we see is not a star 00:10:51.858 --> 00:10:55.852 but an entire galaxy composed of countless stars. 00:10:57.631 --> 00:11:01.694 Astronomers have discovered galaxies are flying away from one another. 00:11:02.505 --> 00:11:05.441 The universe is expanding. 00:11:07.310 --> 00:11:09.939 Our own galaxy, and all the others 00:11:10.114 --> 00:11:13.573 form clusters and superclusters of stupendous size 00:11:13.786 --> 00:11:16.551 hundreds of millions of light-years across. 00:11:20.227 --> 00:11:24.221 And here, about 15 billion light-years from Venice 00:11:24.933 --> 00:11:28.233 we approach the outer limits of the visible universe. 00:11:29.106 --> 00:11:33.771 What lies beyond this cosmic horizon, we cannot see 00:11:35.113 --> 00:11:37.048 and do not know. 00:11:52.936 --> 00:11:56.931 While Galileo's telescope allowed us to take an outward voyage 00:11:57.008 --> 00:12:00.239 another innovation, here in the Dutch town of Delft 00:12:00.646 --> 00:12:03.638 would lead us on an inward journey of discovery. 00:12:14.531 --> 00:12:16.328 Over three centuries ago 00:12:16.433 --> 00:12:19.995 Anton van Leeuwenhoek perfected the early microscope 00:12:20.271 --> 00:12:23.571 and used it to study droplets from the waterways of Holland. 00:12:42.333 --> 00:12:44.267 Come on, over here. 00:12:47.806 --> 00:12:50.207 As students today make their own discoveries 00:12:50.277 --> 00:12:52.644 imagine the moment when van Leeuwenhoek 00:12:52.713 --> 00:12:55.147 peered through his more powerful instrument 00:12:55.216 --> 00:12:59.587 and discovered a living kingdom in a drop of water. 00:13:07.799 --> 00:13:10.701 This busy world of single-cell paramecia 00:13:11.037 --> 00:13:13.233 is only one millimeter across. 00:13:13.874 --> 00:13:17.242 Three powers of ten smaller than a meter. 00:13:21.350 --> 00:13:25.845 The microscope allows us to continue our journey to the realm of the very small. 00:13:27.325 --> 00:13:29.486 As we move into the cell nucleus 00:13:30.094 --> 00:13:32.586 each new ring now reveals a world 00:13:32.798 --> 00:13:36.428 ten times smaller in diameter than the last. 00:13:39.707 --> 00:13:42.040 Deep within the nucleus 00:13:42.110 --> 00:13:44.841 we come upon truly remarkable constructions. 00:13:45.715 --> 00:13:49.049 Long, spiraling molecules of DNA. 00:13:52.023 --> 00:13:54.116 DNA holds the chemical codes 00:13:54.192 --> 00:13:57.321 for the reproduction of most organisms on the planet. 00:13:57.830 --> 00:14:01.825 Whether they're paramecia, people or petunias. 00:14:09.279 --> 00:14:11.713 Voyaging on, we see that molecules 00:14:11.781 --> 00:14:14.717 are made of even smaller parts called atoms. 00:14:20.993 --> 00:14:24.191 The tiny world of the common atom is very strange indeed. 00:14:25.299 --> 00:14:28.736 lts six electrons seem to swarm everywhere at once. 00:14:32.574 --> 00:14:34.907 Now our voyage takes us through a void 00:14:34.978 --> 00:14:38.210 that appears as vast as the space between the stars. 00:14:39.684 --> 00:14:42.085 Ahead lies the atomic nucleus. 00:14:42.654 --> 00:14:44.520 So fantastically small 00:14:45.024 --> 00:14:48.153 that if the whole atom were the size of this theater 00:14:48.228 --> 00:14:51.255 its nucleus would be like a speck of dust. 00:14:52.701 --> 00:14:56.331 Yet the nucleus contains almost all of the atom's mass 00:14:56.906 --> 00:14:59.273 packed into particles called protons 00:14:59.609 --> 00:15:00.975 and neutrons. 00:15:02.747 --> 00:15:07.651 And these, in turn, are made of smaller, more mysterious things called quarks. 00:15:11.559 --> 00:15:12.992 Exploring this 00:15:13.194 --> 00:15:15.322 the inner frontier of the universe 00:15:15.397 --> 00:15:18.025 physicists wonder if quarks might contain 00:15:18.101 --> 00:15:20.569 even tinier building blocks of matter. 00:15:28.113 --> 00:15:33.075 Scientists are investigating this mystery in an underground tunnel near Chicago 00:15:33.720 --> 00:15:37.020 home of the giant Fermilab particle accelerator 00:15:37.625 --> 00:15:43.122 designed to create conditions like those after the birth of our universe. 00:15:46.871 --> 00:15:49.602 Millions of protons and antiprotons 00:15:49.674 --> 00:15:52.404 race through these pipes in opposite directions 00:15:52.477 --> 00:15:57.041 nearly at the speed of light. A kind of subatomic demolition derby. 00:16:26.054 --> 00:16:29.991 Now our cosmic voyage enters another dimension 00:16:31.295 --> 00:16:33.354 the dimension of time 00:16:33.697 --> 00:16:35.962 where knowledge is much less certain. 00:16:36.801 --> 00:16:39.896 Studying traces of quarks from these collisions 00:16:40.239 --> 00:16:44.074 physicists try to learn what our universe was like when it began 00:16:44.144 --> 00:16:47.273 after the explosion known as the Big Bang. 00:16:50.285 --> 00:16:52.345 One of them outlines the theory. 00:16:53.256 --> 00:16:54.814 Welcome to Fermilab. 00:16:55.158 --> 00:16:57.889 Today, astronomers see the universe expanding. 00:16:58.028 --> 00:17:00.463 lmagine running the expansion backwards. 00:17:00.632 --> 00:17:02.099 Billions of years ago 00:17:02.167 --> 00:17:05.467 everything must've been packed together at enormous density. 00:17:05.570 --> 00:17:06.800 lt seems incredible 00:17:06.906 --> 00:17:08.534 but we think that the matter 00:17:08.642 --> 00:17:12.079 making up everything we see in the universe 00:17:12.480 --> 00:17:16.474 the buildings, trees, people, planets 00:17:16.720 --> 00:17:19.314 stars out to the most distant galaxies 00:17:19.924 --> 00:17:23.917 was once crammed together into a volume smaller than this. 00:17:24.829 --> 00:17:26.058 And then. 00:17:42.185 --> 00:17:45.986 Space itself exploded, in a burst of radiant energy. 00:17:48.260 --> 00:17:50.524 ln those first dazzling moments 00:17:50.796 --> 00:17:54.734 the newborn universe began to expand and cool. 00:17:56.137 --> 00:17:58.834 Quarks combined into protons and neutrons 00:17:59.474 --> 00:18:02.774 which later attracted electrons to form atoms 00:18:03.746 --> 00:18:06.477 and the vast fog lifted. 00:18:21.035 --> 00:18:22.970 For hundreds of millions of years 00:18:23.038 --> 00:18:27.066 the force of gravities slowly drew matter together into a gigantic web. 00:18:27.944 --> 00:18:30.311 The architecture of the cosmos. 00:18:36.789 --> 00:18:38.757 Two billion years passed 00:18:39.727 --> 00:18:43.596 clouds of gas and dust condensed like giant water drops 00:18:43.665 --> 00:18:46.658 along the cosmic strands and formed galaxies. 00:18:59.952 --> 00:19:02.251 Where the great ridges of matter crossed 00:19:02.322 --> 00:19:04.723 galaxies came together in clusters. 00:19:30.124 --> 00:19:33.026 Some galaxies evolved into gigantic discs 00:19:33.395 --> 00:19:36.092 and spirals of stars, gas, and dust. 00:19:37.934 --> 00:19:40.870 Neighboring galaxies trapped by their mutual gravity 00:19:41.372 --> 00:19:44.171 draw together in the fantastic collision. 00:19:45.478 --> 00:19:48.311 ln real time, it would last a billion years. 00:20:27.365 --> 00:20:30.995 The force of gravities stretch long tails of gas and stars 00:20:31.103 --> 00:20:32.934 from the huge new galaxy. 00:20:36.076 --> 00:20:38.136 And yet stars almost never collide 00:20:39.247 --> 00:20:41.614 so vast are the distances between them. 00:20:52.063 --> 00:20:54.258 Perhaps ten billion years pass 00:20:54.967 --> 00:20:57.128 and we encounter our own galaxy: 00:20:57.303 --> 00:20:58.703 The Milky Way. 00:20:59.706 --> 00:21:01.834 ln it, stars have formed 00:21:02.944 --> 00:21:04.673 and some have died. 00:21:09.719 --> 00:21:12.280 Stars are nuclear furnaces. 00:21:12.490 --> 00:21:14.981 They shine until they use up their fuel. 00:21:15.359 --> 00:21:17.988 Massive stars end explosively. 00:21:32.682 --> 00:21:35.709 These exploding stars, or supernovas 00:21:36.521 --> 00:21:38.580 send out the elements of life: 00:21:38.957 --> 00:21:42.359 The oxygen we breathe, the carbon in our muscles 00:21:42.461 --> 00:21:44.191 the iron in our blood. 00:21:45.599 --> 00:21:47.568 Now a cloud of cosmic gas 00:21:47.802 --> 00:21:51.398 sprinkled with these elements, comes together in the grip of gravity. 00:21:57.348 --> 00:22:00.613 A new star, our sun, ignites. 00:22:03.722 --> 00:22:05.714 Around it, planets form. 00:22:08.595 --> 00:22:12.259 ln their infancy, over four billion years ago 00:22:12.767 --> 00:22:15.669 our Earth and moon were bombarded constantly 00:22:15.738 --> 00:22:18.105 by cosmic dust, asteroids 00:22:19.476 --> 00:22:20.704 and comets. 00:23:16.315 --> 00:23:19.615 With violent impacts and volcanic gases 00:23:19.820 --> 00:23:23.882 acid rain, and potent ultraviolet radiation from the sun 00:23:24.660 --> 00:23:27.220 the young Earth was a very hostile world. 00:23:30.800 --> 00:23:34.670 And yet the basic ingredients of life are already here. 00:23:41.949 --> 00:23:42.938 Water 00:23:43.784 --> 00:23:44.945 carbon 00:23:45.754 --> 00:23:47.312 and energy. 00:23:50.626 --> 00:23:54.996 Molecules, sheltered by the sea, somehow combined 00:23:55.098 --> 00:23:58.000 multiplied, and gave rise to life. 00:23:58.436 --> 00:24:03.102 For millions of years, Earth's only organisms were tiny bacteria. 00:24:03.743 --> 00:24:07.009 Some, called blue-green bacteria 00:24:07.181 --> 00:24:10.481 slowly released tiny bubbles of oxygen 00:24:11.019 --> 00:24:14.581 and profoundly changed the atmosphere. 00:24:16.693 --> 00:24:21.859 Above the clouds, some of this oxygen formed a thin layer of ozone 00:24:22.133 --> 00:24:25.626 blocking most of the sun's ultraviolet rays. 00:24:30.978 --> 00:24:33.378 ln this changed environment 00:24:33.649 --> 00:24:36.550 new organisms flourished in the Earth's waters. 00:24:38.121 --> 00:24:41.649 Colonies of green algae produced more oxygen. 00:24:50.002 --> 00:24:53.962 Then, organisms evolved in an astonishing variety of forms. 00:24:55.810 --> 00:24:59.975 Some with shells or skeletons for protection and support. 00:25:10.028 --> 00:25:14.989 Others evolved complex life cycles, like this tiny crustacean. 00:25:16.437 --> 00:25:21.535 The shallow waters of the seas filled with a teaming diversity of life forms. 00:25:34.727 --> 00:25:39.428 Life's next challenge was to colonize the harsh, dry land. 00:25:42.938 --> 00:25:47.899 Bacteria were first, followed by algae, plants, and animals. 00:26:13.376 --> 00:26:17.872 Vertebrates appeared on land, feeding on both plants and animals 00:26:19.585 --> 00:26:23.249 and gave rise to larger and larger life forms. 00:26:26.860 --> 00:26:29.421 Some of them conquered the realm of the air 00:26:30.632 --> 00:26:33.727 and others, the great open plains. 00:26:54.196 --> 00:26:58.099 Our cosmic voyage, from the Big Bang to the appearance of humans 00:26:58.167 --> 00:27:01.194 took about 15 billion years. 00:27:03.008 --> 00:27:05.772 From the beginning, we were explorers 00:27:06.345 --> 00:27:09.212 inventors and technicians. 00:27:17.860 --> 00:27:22.230 And in a few thousand years, just an instant in cosmic time 00:27:22.699 --> 00:27:27.570 curiosity and technology would take us back toward the stars. 00:27:57.744 --> 00:27:59.906 Since it was launched into orbit 00:28:00.081 --> 00:28:02.778 the Hubble space telescope has captured images 00:28:02.851 --> 00:28:05.081 that reveal ever more beautiful 00:28:05.154 --> 00:28:09.421 and mysterious regions of the universe, where stars are dying out. 00:28:13.898 --> 00:28:15.799 And within the Eagle Nebula 00:28:15.968 --> 00:28:20.269 strange towers of glowing gas are giving birth to new stars. 00:28:22.543 --> 00:28:24.534 ln the great Orion Nebula 00:28:24.612 --> 00:28:29.745 discs of dust seem to be turning into solar systems just like our own. 00:28:33.691 --> 00:28:37.958 The grand adventure of cosmic exploration is accelerating rapidly 00:28:38.196 --> 00:28:42.065 taking us into realms that once were the stuff of science fiction 00:28:42.402 --> 00:28:45.338 like the mysterious black hole. 00:28:50.846 --> 00:28:55.045 Here, a red giant star is slowly being consumed 00:28:55.218 --> 00:28:58.916 its gases swirling into the depths of a black hole. 00:29:03.595 --> 00:29:07.931 Some black holes may be collapsed cores of very massive stars 00:29:08.302 --> 00:29:12.467 with gravity so powerful not even light can escape them. 00:29:13.008 --> 00:29:17.469 But they can be detected from their trap and swallow nearby stars. 00:29:27.393 --> 00:29:29.555 For the first time in our history 00:29:29.629 --> 00:29:34.158 we now have strong evidence that there are planets orbiting other stars. 00:29:35.904 --> 00:29:40.365 Scientists think there could be millions of earth-like planets in our galaxy alone. 00:29:44.615 --> 00:29:47.710 lf so, do any of them have life? 00:29:52.592 --> 00:29:54.788 Some radio telescopes search for signals 00:29:54.895 --> 00:29:58.127 that may reveal the presence of alien civilizations. 00:29:59.802 --> 00:30:01.292 lt's a daunting task. 00:30:02.071 --> 00:30:05.166 But, if one day we should receive a signal 00:30:05.709 --> 00:30:08.645 it would forever change our view of ourselves 00:30:09.313 --> 00:30:10.975 and our universe. 00:30:36.315 --> 00:30:40.252 Telescopes, such as the giant Keck Observatory in Hawaii 00:30:40.487 --> 00:30:43.651 are like time machines capturing the faint light 00:30:43.724 --> 00:30:47.161 that has traveled towards us through all of cosmic history. 00:30:48.030 --> 00:30:52.969 The deeper astronomers look into space, the farther back they see in time. 00:31:09.425 --> 00:31:11.757 The more we learn about the universe 00:31:12.294 --> 00:31:14.627 the more new mysteries we uncover 00:31:15.165 --> 00:31:20.264 profound questions for future generations of cosmic explorers. 00:31:23.977 --> 00:31:27.345 Will the universe go on expanding forever? 00:31:28.182 --> 00:31:30.617 Exactly how did life arise? 00:31:31.553 --> 00:31:35.115 Could there be other universes beyond our cosmic horizon? 00:31:35.925 --> 00:31:38.895 And are there others elsewhere in the universe 00:31:39.096 --> 00:31:40.997 asking the same things? 00:31:41.799 --> 00:31:45.236 Even to ask such questions is ambitious. 00:31:45.971 --> 00:31:49.305 But look how far we've traveled since our ancestors 00:31:49.376 --> 00:31:52.869 took the first steps in our cosmic voyage. 00:33:30.038 --> 00:33:34.635 Man must understand his universe in order to understand his destiny. 00:33:35.980 --> 00:33:39.678 Who knows what mysteries will be solved in our lifetime 00:33:40.051 --> 00:33:44.352 and what new riddles will become the challenge of the new generations?