0 00:00:04,971 --> 00:00:07,337 How much time can you imagine? 1 00:00:08,742 --> 00:00:10,141 A hundred years? 2 00:00:11,845 --> 00:00:13,107 A thousand? 3 00:00:15,448 --> 00:00:16,813 A million years? 4 00:00:20,920 --> 00:00:24,686 Our earth holds clues to the immensity of time. 5 00:00:26,926 --> 00:00:29,588 From its ancient beginnings and violent past, 6 00:00:29,863 --> 00:00:33,355 the Earth has revolutionised how we understand time. 7 00:00:35,702 --> 00:00:38,967 Time is more vast than we ever imagined. 8 00:00:40,106 --> 00:00:42,006 And that's raising new questions. 9 00:00:42,776 --> 00:00:44,641 About our ancestral roots. 10 00:00:45,645 --> 00:00:48,910 About our connection to life's oldest secrets. 11 00:00:51,618 --> 00:00:54,815 Our Earth is revealing our place in time. 12 00:00:56,356 --> 00:00:59,018 And ultimately, our future. 13 00:01:29,956 --> 00:01:35,360 Our whole world is shaped by time in ways that are often hidden from us. 14 00:01:42,402 --> 00:01:46,498 Time for most of us is dictated by the rhythms of our daily life. 15 00:01:47,807 --> 00:01:50,867 We get up in the morning, we go to work, we come back at night. 16 00:01:51,377 --> 00:01:55,711 So watching the days and the years pass by can be quite disconcerting. 17 00:01:56,149 --> 00:02:00,813 But what if we could see farther, to a greater horizon of time? 18 00:02:04,124 --> 00:02:08,993 We know that time stretches into a past that existed before we were born. 19 00:02:11,464 --> 00:02:15,924 We can also imagine it rolling on into a future long after we're gone. 20 00:02:17,904 --> 00:02:22,466 Butjust how far back and how far forward does time really go? 21 00:02:23,109 --> 00:02:28,376 And where do we fit into this larger timescale of life and even the Earth? 22 00:02:33,553 --> 00:02:35,180 Answers to these questions 23 00:02:35,255 --> 00:02:39,885 are now fundamentally changing our sense of who we are 24 00:02:39,959 --> 00:02:42,359 and even what it means to be human. 25 00:02:43,763 --> 00:02:45,196 In this programme, 26 00:02:45,265 --> 00:02:48,792 I'm going to explore the huge scale of Earth Time, 27 00:02:49,536 --> 00:02:51,663 its beginning and its end, 28 00:02:52,405 --> 00:02:54,498 and our place within it. 29 00:03:05,318 --> 00:03:08,344 On a rugged cliff of granite in South Dakota, 30 00:03:08,521 --> 00:03:13,220 stone masons risk life and limb to create something unique. 31 00:03:19,933 --> 00:03:22,333 The world's largest sculpture. 32 00:03:24,270 --> 00:03:26,534 It's a memorial to Crazy Horse, 33 00:03:26,839 --> 00:03:30,434 the native American chief from the 19th century. 34 00:03:31,444 --> 00:03:36,507 But it's also a monument to a uniquely human sense of time, 35 00:03:37,150 --> 00:03:42,281 one that allows us to imagine a future beyond our own lives. 36 00:03:46,793 --> 00:03:50,092 Ruth Ziolkowskiis in charge of the carving. 37 00:03:50,663 --> 00:03:52,688 This is her life's work. 38 00:03:53,766 --> 00:03:56,257 I think sometimes people get into projects 39 00:03:56,336 --> 00:03:59,601 such as cathedrals or carving a mountain or the sphinx 40 00:03:59,672 --> 00:04:02,641 and anything that's going to take a long, long time; 41 00:04:03,243 --> 00:04:06,041 they usually think oh, this is going to take me 30 or 40 years, 42 00:04:06,112 --> 00:04:07,636 and then all of a sudden when you get started 43 00:04:07,714 --> 00:04:10,808 it's going to be your lifetime and several more generations. 44 00:04:12,619 --> 00:04:17,955 Five, four, fire... 45 00:04:20,893 --> 00:04:25,762 Ruth's faith in a future that stretches far, far beyond her own life 46 00:04:25,832 --> 00:04:28,232 is shared by three generations. 47 00:04:31,704 --> 00:04:35,367 Monique, a sculptor, is one of Ruth's seven children. 48 00:04:37,677 --> 00:04:41,113 I work here because I believe in what we're doing, 49 00:04:41,914 --> 00:04:46,248 and the purpose of Crazy Horse is way more than a mountain carving. 50 00:04:48,521 --> 00:04:52,855 The family is continuing the work of Ruth's husband, Korczak. 51 00:04:54,527 --> 00:04:55,824 In 1940, 52 00:04:55,895 --> 00:04:58,796 the young sculptor was invited by Standing Bear, 53 00:04:58,965 --> 00:05:03,902 Chief of the Lakota, to create a fitting memorial to Crazy Horse, 54 00:05:04,137 --> 00:05:06,071 their great warrior leader. 55 00:05:07,707 --> 00:05:09,334 Korczak accepted the challenge, 56 00:05:09,409 --> 00:05:12,845 and set to work with little more than ajackhammer 57 00:05:12,912 --> 00:05:15,142 and a monumental ambition. 58 00:05:18,785 --> 00:05:22,516 His vision for this project was so big, 59 00:05:23,022 --> 00:05:26,890 I don't think he even realised what it was going to entail. 60 00:05:28,728 --> 00:05:32,095 Korczak didn't think it was important to see it finished himself, 61 00:05:32,465 --> 00:05:34,695 or for anyone of us to see it finished. 62 00:05:34,901 --> 00:05:37,961 He said, 'the important thing is that you keep on working 63 00:05:38,037 --> 00:05:39,197 and you never stop.' 64 00:05:41,174 --> 00:05:46,111 Korczak kept carving away the mountain till his death in 1982. 65 00:05:50,049 --> 00:05:51,311 But it's only recently, 66 00:05:51,484 --> 00:05:53,975 50 years since Korczak began work, 67 00:05:54,053 --> 00:05:58,251 that Crazy Horse's huge 90-foot face is complete. 68 00:06:06,366 --> 00:06:10,666 It's anybody's guess exactly when the sculpture will be finished. 69 00:06:11,571 --> 00:06:14,836 I don't have the foggiest idea how long it's going to take. 70 00:06:15,108 --> 00:06:17,099 I honestly don't think Korczak did. 71 00:06:21,481 --> 00:06:26,282 Korczak's vision reflects a deep and fundamental human belief, 72 00:06:26,886 --> 00:06:31,084 that time exists far beyond our own experience. 73 00:06:34,293 --> 00:06:37,592 I think it's incredible that dad could come out here 74 00:06:37,663 --> 00:06:39,460 with nothing, nothing at all - 75 00:06:40,600 --> 00:06:44,036 and erm to see so far into the future. 76 00:06:45,738 --> 00:06:48,366 To be a part of that, it makes you very humble. 77 00:06:50,309 --> 00:06:52,869 We hope it will grow and plan that it will, 78 00:06:53,212 --> 00:06:55,680 and it's for the Indian people tomorrow 79 00:06:55,848 --> 00:06:59,682 and on into the future for as many generations as it continues. 80 00:07:01,521 --> 00:07:05,150 It's a dream that's becoming a legacy. 81 00:07:14,400 --> 00:07:19,030 Such legacies rely on a uniquely human concept of time. 82 00:07:20,673 --> 00:07:23,141 Our monuments testify to a certainty 83 00:07:23,209 --> 00:07:26,178 that time will always continue onwards. 84 00:07:29,882 --> 00:07:33,784 It stretches forwards into an unknowable future. 85 00:07:34,954 --> 00:07:38,651 And back into a dim and distant past. 86 00:07:48,100 --> 00:07:51,968 Our knowledge of time lies at the very heart of our humanity. 87 00:07:52,538 --> 00:07:53,971 We learn from the past, 88 00:07:54,040 --> 00:07:56,372 we pass on that wisdom to the future. 89 00:07:56,843 --> 00:07:59,710 That's been the bedrock of our civilisation. 90 00:08:03,483 --> 00:08:05,610 The relentless march of progress, 91 00:08:06,652 --> 00:08:08,643 the world we live in today, 92 00:08:09,555 --> 00:08:14,754 all that rests upon the accumulation of thousands of years of time. 93 00:08:16,796 --> 00:08:18,559 On the wall of Einstein's office, 94 00:08:18,898 --> 00:08:22,168 he used to keep photographs of all his predecessors 95 00:08:22,168 --> 00:08:24,932 to remind himself of the great debt that he owed them. 96 00:08:25,204 --> 00:08:26,171 In other words, 97 00:08:26,239 --> 00:08:28,537 we all stand on the shoulders of giants. 98 00:08:29,041 --> 00:08:31,737 There's no Shakespeare without classical Greece; 99 00:08:31,978 --> 00:08:33,878 there's no Einstein without Newton; 100 00:08:34,380 --> 00:08:36,007 there are no skyscrapers 101 00:08:36,148 --> 00:08:37,513 without the skill 102 00:08:37,583 --> 00:08:41,075 of generations of builders going back to the dawn of history. 103 00:08:45,858 --> 00:08:49,851 This awareness that time stretches into a distant past 104 00:08:50,296 --> 00:08:52,526 has driven us for thousands of years 105 00:08:52,598 --> 00:08:56,056 to ask one of the greatest questions of humanity. 106 00:08:59,205 --> 00:09:02,072 When did time itself begin? 107 00:09:09,115 --> 00:09:10,776 In the 17th century, 108 00:09:10,850 --> 00:09:14,308 an archbishop from Dublin decided to find out. 109 00:09:16,489 --> 00:09:17,751 For James Ussher, 110 00:09:17,823 --> 00:09:21,452 the beginning of time was the moment of God's creation, 111 00:09:21,861 --> 00:09:25,695 of the Earth, the heavens, and all of humanity. 112 00:09:27,433 --> 00:09:30,334 So he started with the old testament. 113 00:09:32,805 --> 00:09:34,238 All Ussher really had to do 114 00:09:34,307 --> 00:09:36,502 was add up the various ages of the patriarchs. 115 00:09:36,576 --> 00:09:41,013 Because the bible tells us what age each person was when his son was born. 116 00:09:41,080 --> 00:09:42,479 So, for example 117 00:09:42,548 --> 00:09:47,576 Genesis 5 tell us that Adam was 130 years old when his son Seth was born. 118 00:09:47,653 --> 00:09:50,850 Seth was 105 years old when his son Enoch was born. 119 00:09:52,959 --> 00:09:57,293 But at the end of the Old Testament, the family trees run out. 120 00:09:59,599 --> 00:10:01,863 Finally, in 1650, 121 00:10:01,968 --> 00:10:05,563 he determined a date for the beginning of time. 122 00:10:06,906 --> 00:10:08,840 With stunning precision. 123 00:10:09,709 --> 00:10:11,336 In the very first paragraph 124 00:10:11,410 --> 00:10:13,640 Ussher dates the creation of the world 125 00:10:13,713 --> 00:10:18,582 to exactly the evening before the 23rd October 4004 BC. 126 00:10:22,054 --> 00:10:26,548 James Ussher had established the very moment of God's creation. 127 00:10:29,161 --> 00:10:32,324 Our place was at the centre of the universe, 128 00:10:32,398 --> 00:10:35,299 the Earth created for our purpose. 129 00:10:36,535 --> 00:10:42,565 Humanity, the Earth and time itself were six thousand years old. 130 00:10:48,014 --> 00:10:49,914 Compared to our lifetime, 131 00:10:49,982 --> 00:10:53,509 six thousand years is an incredible amount of time. 132 00:10:54,553 --> 00:10:56,316 But around a hundred years later, 133 00:10:56,389 --> 00:10:59,085 that timescale was about to be dwarfed. 134 00:11:00,426 --> 00:11:02,724 For all of Ussher's library full of books, 135 00:11:02,795 --> 00:11:06,253 the Earth itself was beginning to present quite a different story. 136 00:11:06,666 --> 00:11:09,396 And the first man to realise there was a problem 137 00:11:09,468 --> 00:11:12,631 was a Scottish farmer by the name of James Hutton. 138 00:11:12,705 --> 00:11:13,399 There he is. 139 00:11:14,573 --> 00:11:16,165 James Hutton spent most of his life 140 00:11:16,242 --> 00:11:19,609 marvelling at natural processes, mainly on his own farm. 141 00:11:20,146 --> 00:11:25,083 And his investigations would lead to an entirely new idea of time. 142 00:11:27,420 --> 00:11:29,115 I'm about to look for the clues 143 00:11:29,188 --> 00:11:32,089 that led Hutton to rethink the age of the earth 144 00:11:32,525 --> 00:11:36,256 and overturn Ussher's six thousand year history. 145 00:11:37,163 --> 00:11:39,893 Geologist Dave Thayer is going to be my guide. 146 00:11:40,800 --> 00:11:44,531 Well, I think it's ironic that people used to wonder how old is the Earth? 147 00:11:44,870 --> 00:11:49,239 But the answer was underneath their feet in the rocks all the time. 148 00:11:49,442 --> 00:11:50,841 They were walking on the answer. 149 00:11:50,943 --> 00:11:53,605 Yes, and they just didn't have the knowledge of er, 150 00:11:53,679 --> 00:11:57,615 finding out how to er, open that book and read the - read the answer. 151 00:11:58,050 --> 00:12:00,610 So Dave er, what are we going to see on this journey now? 152 00:12:01,620 --> 00:12:04,111 We're going to gaze into an abyss of time. 153 00:12:04,824 --> 00:12:07,190 Many people come to the place we're approaching, 154 00:12:07,993 --> 00:12:11,656 and they don't really understand what they're looking at. 155 00:12:18,137 --> 00:12:21,368 James Hutton's insights came from Scotland. 156 00:12:22,274 --> 00:12:23,901 But Dave's brought me to a place 157 00:12:23,976 --> 00:12:28,174 where the same features have been carved out on a much larger scale. 158 00:12:37,857 --> 00:12:40,690 The Grand Canyon in Arizona. 159 00:12:42,128 --> 00:12:46,656 270 miles of Colorado river flow across two states, 160 00:12:46,899 --> 00:12:49,891 carving out a chasm one mile deep. 161 00:12:53,539 --> 00:12:57,168 It's created a landscape on an epic scale. 162 00:13:06,385 --> 00:13:07,943 Let's have a seat here. 163 00:13:09,622 --> 00:13:12,250 Now Dave, the Colorado river is a small little thing. 164 00:13:12,625 --> 00:13:16,527 How can the Colorado river gouge out such a huge canyon? 165 00:13:17,196 --> 00:13:19,494 The river is digging the canyon deeper 166 00:13:19,565 --> 00:13:21,726 at the rate of one foot every thousand years. 167 00:13:22,501 --> 00:13:24,093 And in that time 168 00:13:24,870 --> 00:13:28,465 it -just all this rubble is eroding down into it from the rain. 169 00:13:28,774 --> 00:13:29,741 - I see. - You can imagine 170 00:13:29,809 --> 00:13:32,744 how long that's taking, because it's all changed into sand as it goes. 171 00:13:35,047 --> 00:13:39,245 A mile below us, the river continues to cut its path through the rock, 172 00:13:40,219 --> 00:13:42,779 carrying it away in its silty waters. 173 00:13:45,958 --> 00:13:47,926 So we're talking about the power of water, right? 174 00:13:47,993 --> 00:13:51,793 I mean, water, water carved this cathedral out of nothing? 175 00:13:51,864 --> 00:13:52,990 Yep. Yeah. 176 00:13:53,399 --> 00:13:55,993 And how long has this erosion been taking place? 177 00:13:56,202 --> 00:13:59,228 Well, at least five and a half million years is what they say. 178 00:14:03,876 --> 00:14:05,741 Following similar clues, 179 00:14:05,911 --> 00:14:06,741 Hutton realised 180 00:14:06,812 --> 00:14:11,249 that Ussher's six thousand year age for earth had to be wrong. 181 00:14:15,187 --> 00:14:19,681 Unimaginable eons of time were needed for water to carve out valleys. 182 00:14:27,766 --> 00:14:30,064 And Hutton noticed something else. 183 00:14:31,470 --> 00:14:37,409 The layers of rock revealed by erosion showed a still greater scale of time. 184 00:14:38,410 --> 00:14:41,436 Now Dave, when I look at a rock, it's boring. 185 00:14:41,513 --> 00:14:43,344 A rock is a rock is a rock. 186 00:14:43,582 --> 00:14:46,346 But you're telling me that each rock has a story, right? 187 00:14:46,986 --> 00:14:48,248 Well, that's true Michio. 188 00:14:48,320 --> 00:14:51,881 Erm, er, you can see all the different colours of the layers in the canyon, 189 00:14:52,491 --> 00:14:55,255 and each one has a different thing to tell. 190 00:14:56,629 --> 00:14:57,653 Amazingly, 191 00:14:57,730 --> 00:15:00,392 long, long before the rock was eroded away, 192 00:15:00,566 --> 00:15:03,034 its layers had to have been formed. 193 00:15:03,402 --> 00:15:05,495 Well, here's a nice place to see the strata. 194 00:15:06,338 --> 00:15:07,930 I see yeah, right here. 195 00:15:08,007 --> 00:15:08,405 Yes. 196 00:15:08,574 --> 00:15:10,064 This red layer right here 197 00:15:10,142 --> 00:15:12,633 would be a silt stone that formed at the edge of an ocean. 198 00:15:13,112 --> 00:15:13,771 And you know, 199 00:15:13,846 --> 00:15:16,076 it took probably a thousand years to form one inch of it. 200 00:15:16,148 --> 00:15:17,979 A thousand years. 201 00:15:18,050 --> 00:15:19,381 So you're telling me that 202 00:15:19,451 --> 00:15:21,248 all of human recorded history 203 00:15:21,320 --> 00:15:24,050 going right back to the Babylonians and the Egyptians 204 00:15:24,123 --> 00:15:24,748 Would be just that much. 205 00:15:24,823 --> 00:15:25,687 Just a few inches. 206 00:15:25,758 --> 00:15:26,952 Isn't that staggering? Yeah. 207 00:15:27,059 --> 00:15:30,187 So this is like a - like a time machine, basically, right. 208 00:15:30,262 --> 00:15:32,253 Er, a thousand years per inch on average. 209 00:15:32,331 --> 00:15:33,320 On average er, yeah. 210 00:15:33,399 --> 00:15:34,798 If you - if you just took the whole 211 00:15:34,867 --> 00:15:36,596 length ofjust the sedimentary rocks in the canyon 212 00:15:36,669 --> 00:15:38,432 that have been deposited here. 213 00:15:39,772 --> 00:15:43,208 Floods and rivers and streams and the ocean coming in. 214 00:15:43,275 --> 00:15:44,401 It staggers the imagination. 215 00:15:44,476 --> 00:15:45,204 It does indeed. 216 00:15:47,746 --> 00:15:48,440 In fact, 217 00:15:48,514 --> 00:15:51,745 just six inches of the Grand Canyon's rock face 218 00:15:51,817 --> 00:15:56,117 is equivalent to Ussher's timescale for the whole of Earth's existence. 219 00:15:57,756 --> 00:16:01,715 The Earth had begun to reveal the true immensity of time. 220 00:16:04,596 --> 00:16:07,497 A scale of time that was inconceivable. 221 00:16:09,301 --> 00:16:11,292 An unending abyss. 222 00:16:15,374 --> 00:16:17,308 For me, Hutton wrote a great passage 223 00:16:17,376 --> 00:16:20,834 which summarises the experience of the Grand Canyon, 224 00:16:21,180 --> 00:16:22,272 and that is: 225 00:16:22,681 --> 00:16:25,775 'The result, therefore, of our present inquiry 226 00:16:25,851 --> 00:16:29,048 is that we find no vestige of a beginning, 227 00:16:29,288 --> 00:16:31,051 no prospect for an end.' 228 00:16:33,926 --> 00:16:37,054 The great vastness of Earth time had been revealed 229 00:16:38,564 --> 00:16:40,930 and a scientific quest had begun. 230 00:16:41,567 --> 00:16:43,899 If the Earth wasn't six thousand years old, 231 00:16:44,136 --> 00:16:46,400 then just how old was it? 232 00:16:49,675 --> 00:16:54,044 It's a question that has only finally been answered in the last few decades. 233 00:17:03,922 --> 00:17:08,325 Sam Bowring is a specialist at dating rocks from all over the world. 234 00:17:10,729 --> 00:17:12,026 Back in the 1980s, 235 00:17:12,131 --> 00:17:16,591 he collected a sample from Canada which lay forgotten in his office. 236 00:17:19,405 --> 00:17:21,839 It held an amazing secret. 237 00:17:23,108 --> 00:17:26,712 Other than noting its presence and thinking it was pretty interesting, 238 00:17:26,712 --> 00:17:30,808 I didn't actually begin to work on the rocks for another four years. 239 00:17:32,518 --> 00:17:34,611 When Sam got round to study the rock, 240 00:17:34,887 --> 00:17:37,151 he wanted to discover its age, 241 00:17:37,356 --> 00:17:40,120 so he extracted a mineral called zircon. 242 00:17:43,195 --> 00:17:45,459 Present in nearly every rock on earth, 243 00:17:45,664 --> 00:17:48,565 it's a treasure to anyone interested in time. 244 00:17:49,935 --> 00:17:52,495 The mineral zircon, when it forms in a rock, 245 00:17:52,571 --> 00:17:56,405 incorporates uranium into its crystal structure. 246 00:17:57,009 --> 00:17:58,772 So it's like a little time capsule, 247 00:17:58,844 --> 00:18:03,440 because over time the uranium decays to lead. 248 00:18:05,017 --> 00:18:09,579 This decay from one element to another is like a ticking clock. 249 00:18:09,922 --> 00:18:12,550 It happens at a slow universal rate. 250 00:18:13,992 --> 00:18:17,758 Measure the proportion of uranium to lead in the zircon 251 00:18:17,996 --> 00:18:20,624 and you know the age of the rock it came from. 252 00:18:26,605 --> 00:18:28,698 Like thousands of other samples, 253 00:18:29,007 --> 00:18:31,737 the Canadian rock appeared unremarkable. 254 00:18:36,281 --> 00:18:38,146 But when the results emerged, 255 00:18:38,250 --> 00:18:42,186 Sam realised the rock's true significance. 256 00:18:43,689 --> 00:18:45,179 I remember very clearly - 257 00:18:45,390 --> 00:18:48,848 seeing the numbers come off the mass spectrometer on the screen. 258 00:18:51,830 --> 00:18:54,890 That was the first time we knew that we had a very old rock. 259 00:18:55,901 --> 00:19:00,429 The numbers indicated the longest time span he'd ever seen. 260 00:19:01,640 --> 00:19:06,373 In fact, Sam had discovered the oldest fragment of Earth ever found. 261 00:19:08,380 --> 00:19:09,506 Its age? 262 00:19:10,249 --> 00:19:13,912 An amazing four thousand million years. 263 00:19:23,962 --> 00:19:28,399 Dating rocks like Sam's opens up ever greater depths of time. 264 00:19:29,668 --> 00:19:32,899 But it still doesn't answer that fundamental question: 265 00:19:33,505 --> 00:19:35,905 Just how old is Earth? 266 00:19:38,277 --> 00:19:39,107 The trouble is, 267 00:19:39,178 --> 00:19:39,940 how do you know 268 00:19:40,012 --> 00:19:42,242 when you've found the oldest rock on Earth? 269 00:19:42,481 --> 00:19:43,846 And even after you find it, 270 00:19:43,916 --> 00:19:46,942 how do you know that it was formed at the same time as the Earth? 271 00:19:47,219 --> 00:19:49,517 Well, quite frankly, you don't. 272 00:19:52,291 --> 00:19:54,725 The answer lies in something else, 273 00:19:55,160 --> 00:19:58,391 something that was formed millions of miles away. 274 00:19:58,764 --> 00:20:00,129 I'd like to buy this rock, please. 275 00:20:00,199 --> 00:20:00,893 Right. 276 00:20:01,333 --> 00:20:01,924 Here's the money. 277 00:20:02,000 --> 00:20:03,763 Okay, that'll be 85 cents. 278 00:20:06,171 --> 00:20:08,071 Compared to the other rocks in the shop - 279 00:20:08,240 --> 00:20:10,231 - this rock looks pretty ordinary. 280 00:20:10,642 --> 00:20:14,305 But this rock represents a landmark in our understanding of time. 281 00:20:17,783 --> 00:20:20,183 It comes from outer space. 282 00:20:24,523 --> 00:20:28,857 My rock is a fragment from a giant meteor that left this. 283 00:20:34,266 --> 00:20:37,394 The Berenger meteor crater in Arizona. 284 00:20:44,643 --> 00:20:49,376 300,000 tons of rock from space collided with Earth 285 00:20:49,615 --> 00:20:51,913 and blew the ground apart. 286 00:20:53,518 --> 00:20:55,418 The meteor was so huge, 287 00:20:55,487 --> 00:20:58,217 it ripped house sized boulders from the ground. 288 00:21:02,160 --> 00:21:05,323 Try to imagine a few of these flying through the air. 289 00:21:13,038 --> 00:21:15,734 My fragment is part of that meteor. 290 00:21:16,575 --> 00:21:19,942 It's debris from the very birth of our solar system. 291 00:21:20,812 --> 00:21:22,541 When the solar system first formed, 292 00:21:22,614 --> 00:21:24,605 it was full of rock and debris, 293 00:21:24,683 --> 00:21:27,277 out of which the planets and the Earth condensed. 294 00:21:27,753 --> 00:21:31,712 However, there were some bits and pieces of rock that did not condense. 295 00:21:32,958 --> 00:21:35,188 And those leftover rocks remain, 296 00:21:35,794 --> 00:21:38,729 primitive relics from the birth of the planets. 297 00:21:41,800 --> 00:21:43,700 That's the origin of the meteorites. 298 00:21:43,869 --> 00:21:47,737 They share a common age and common origin with the Earth. 299 00:21:47,806 --> 00:21:53,244 So if you know the date of this rock, then you'd know the age of the Earth. 300 00:21:54,980 --> 00:21:56,447 In 1955, 301 00:21:56,548 --> 00:21:59,574 using radioactive dating on this very meteor, 302 00:21:59,718 --> 00:22:03,814 scientists at last revealed the Earth's true age. 303 00:22:04,456 --> 00:22:08,153 The search that had started with Ussher and Hutton was over. 304 00:22:08,860 --> 00:22:11,852 I imagine that if James Hutton were still alive today 305 00:22:11,930 --> 00:22:13,591 he'd be quite pleased with himself. 306 00:22:13,799 --> 00:22:17,758 He set off on ajourney 200 years ago that he could never complete. 307 00:22:18,170 --> 00:22:22,038 He talked about a vestige of a beginning that he would never see. 308 00:22:22,474 --> 00:22:24,032 Well, today by looking at rocks, 309 00:22:24,109 --> 00:22:26,703 not from Scotland but from outer space, 310 00:22:27,145 --> 00:22:29,579 we can nail that number right to the wall. 311 00:22:31,817 --> 00:22:33,842 Since 1955, 312 00:22:33,919 --> 00:22:36,547 all ways to date the Earth have agreed. 313 00:22:38,056 --> 00:22:42,755 The Earth is 4,600 million years old. 314 00:22:43,762 --> 00:22:46,788 That's 4.6 billion years. 315 00:22:48,567 --> 00:22:51,900 Earth time is unimaginably vast. 316 00:23:10,756 --> 00:23:11,780 It's amazing 317 00:23:11,857 --> 00:23:13,984 that in just a few centuries 318 00:23:14,059 --> 00:23:17,927 our view of the depths of Earth time has changed so radically 319 00:23:18,230 --> 00:23:21,597 that it's completely changed our conception of who we are. 320 00:23:23,368 --> 00:23:27,498 How are weto comprehend this vast ocean of time? 321 00:23:29,641 --> 00:23:33,543 And if we begin to understand the immensity of Earth time, 322 00:23:34,513 --> 00:23:38,176 what does that mean for our sense of our place within it? 323 00:23:43,989 --> 00:23:48,187 Let's say that one millimetre represents one year backwards in time. 324 00:23:48,894 --> 00:23:52,830 Here we are in the present, this is me in the 21st century. 325 00:23:53,432 --> 00:23:58,165 Now, if I go back 5.8 centimetres, then we reach 1947. 326 00:23:58,570 --> 00:24:00,435 That's the year I was born. 327 00:24:01,006 --> 00:24:04,237 Now let's talk about the Roman conquest of England. 328 00:24:04,409 --> 00:24:07,173 That took place in the year 43 AD. 329 00:24:07,512 --> 00:24:11,414 For that we have to go back about 195 centimetres. 330 00:24:12,617 --> 00:24:15,882 To about here. 331 00:24:16,922 --> 00:24:20,881 Even the length of my table represents 2,000 years. 332 00:24:21,426 --> 00:24:24,418 But I want to measure out the whole of earth time. 333 00:24:24,696 --> 00:24:28,996 And 4.6 billion years is going to take me a whole lot further. 334 00:24:35,674 --> 00:24:36,868 On this scale, 335 00:24:36,942 --> 00:24:41,208 every mile is an epoch of nearly two million years. 336 00:24:46,151 --> 00:24:48,949 As the sheer depths of Earth time roll on, 337 00:24:49,521 --> 00:24:53,048 a human lifespan seems so insignificant. 338 00:25:21,219 --> 00:25:24,518 I've travelled two and a half thousand miles. 339 00:25:25,056 --> 00:25:28,184 4.6 billion years of time. 340 00:25:29,027 --> 00:25:31,621 The entire age of the Earth. 341 00:25:35,634 --> 00:25:38,194 It's taken me across the whole of America, 342 00:25:38,737 --> 00:25:44,039 and it's made me feel by comparison very, very small indeed. 343 00:25:54,386 --> 00:25:58,982 Compared to my own 58 years, that's how vast Earth time really is. 344 00:25:59,324 --> 00:26:03,055 My own lifespan is nothing but a pimple on the face of Earth time. 345 00:26:03,595 --> 00:26:08,555 That's what makes 4.6 billion years so captivating, but also so unnerving. 346 00:26:14,172 --> 00:26:16,107 You see, time means change. 347 00:26:16,107 --> 00:26:18,302 Everything changes with time. 348 00:26:18,577 --> 00:26:20,044 The world we see around us 349 00:26:20,111 --> 00:26:22,636 that seems so solid and so permanent, 350 00:26:22,714 --> 00:26:25,581 is literally changing right beneath our own feet. 351 00:26:30,021 --> 00:26:32,785 Our Earth is constantly changing. 352 00:26:33,291 --> 00:26:35,259 But it happens so slowly 353 00:26:35,527 --> 00:26:39,054 that we're simply not around long enough to witness it. 354 00:26:44,035 --> 00:26:47,027 This beach, for example, took millions of years to form. 355 00:26:47,872 --> 00:26:51,364 You see, we can only see the effects of time through change. 356 00:26:51,643 --> 00:26:56,046 And change over millions of years is almost imperceptible. 357 00:27:02,887 --> 00:27:03,854 There are, however, 358 00:27:04,022 --> 00:27:06,422 some places where occasionally 359 00:27:06,491 --> 00:27:09,324 we're able to glimpse these changes in action. 360 00:27:19,137 --> 00:27:21,503 Kalapana, 1990. 361 00:27:23,475 --> 00:27:26,535 This Hawaiian fishing village faced total devastation 362 00:27:26,611 --> 00:27:29,273 from the most active volcano in the world. 363 00:27:32,684 --> 00:27:33,582 Kalawaya. 364 00:27:39,391 --> 00:27:46,263 It's a 90 foot wall of hot molten lava rolling toward your home, 365 00:27:47,198 --> 00:27:52,033 and people just stood there basically, in total disbelief... 366 00:27:54,839 --> 00:27:57,399 And before that lava would hit the home, 367 00:27:57,976 --> 00:28:01,275 homes would just burst into flame - 368 00:28:01,746 --> 00:28:03,805 and people would cry 369 00:28:03,882 --> 00:28:07,443 and er, you know, traumatised to the max, you know. 370 00:28:14,459 --> 00:28:17,257 That lava buried house after house. 371 00:28:24,602 --> 00:28:27,230 Kalapana has gone forever. 372 00:28:30,175 --> 00:28:34,339 It lies 50 feet under a blanket of solid rock. 373 00:28:41,219 --> 00:28:43,847 This was once the road to Kalapana. 374 00:28:50,261 --> 00:28:53,958 For us, such violent events are catastrophic. 375 00:28:55,633 --> 00:28:56,691 But for our Earth, 376 00:28:56,768 --> 00:29:01,603 they are no more than the beats of a much greater timescale of change. 377 00:29:08,947 --> 00:29:10,312 To understand this, 378 00:29:10,415 --> 00:29:14,818 I'm going to take a closer look at the engine that drives this change. 379 00:29:26,131 --> 00:29:29,623 Kalawaya, the world's most active volcano, 380 00:29:29,701 --> 00:29:33,501 has been erupting continuously since 1983. 381 00:29:41,446 --> 00:29:45,280 This is truly a fantastic experience to be literally 382 00:29:45,550 --> 00:29:47,381 face to face with a live volcano. 383 00:29:56,427 --> 00:29:58,895 We're dealing with very primeval forces here. 384 00:29:59,564 --> 00:30:03,591 The power of volcanoes is basically the power of the Earth itself. 385 00:30:05,870 --> 00:30:08,703 But this power isn't only a source of destruction, 386 00:30:09,674 --> 00:30:12,006 it's the creator of new land. 387 00:30:15,413 --> 00:30:18,075 This is one of the youngest parts of our planet, 388 00:30:18,516 --> 00:30:22,043 built from countless layers of solidified lava. 389 00:30:23,555 --> 00:30:27,355 Imagine that each of the Hawaiian islands was created in this fashion. 390 00:30:27,859 --> 00:30:31,056 Volcanoes pushing their way through the crust of the earth, 391 00:30:31,262 --> 00:30:32,229 forming islands. 392 00:30:32,664 --> 00:30:35,326 Island after island after island. 393 00:30:35,400 --> 00:30:38,062 This is the origin of the Hawaiian chain. 394 00:30:38,303 --> 00:30:41,204 And it's still happening right before our eyes. 395 00:30:42,640 --> 00:30:47,202 Over time, this process causes change on a huge scale. 396 00:30:53,751 --> 00:30:57,585 This island was created by volcanoes 800,000 years ago - 397 00:30:58,089 --> 00:30:59,147 and it's still growing, 398 00:30:59,224 --> 00:31:01,954 at the rate of about a square mile every 20 years. 399 00:31:02,126 --> 00:31:05,562 And you can actually see that process happening right over there. 400 00:31:07,098 --> 00:31:09,328 Already 20 miles to the south, 401 00:31:09,500 --> 00:31:11,297 3,000 feet under water, 402 00:31:11,369 --> 00:31:14,236 yet another volcano is being born. 403 00:31:14,772 --> 00:31:17,070 Lava is pouring out of the Earth's crust, 404 00:31:17,208 --> 00:31:20,200 creating what will be the next Hawaiian island. 405 00:31:20,645 --> 00:31:22,772 And in 200,000 years 406 00:31:22,847 --> 00:31:27,011 that could be as big as the island that I'm standing on right now. 407 00:31:28,353 --> 00:31:31,720 The creation of the entire chain of Hawaiian islands 408 00:31:31,789 --> 00:31:34,314 took 43 million years. 409 00:31:35,460 --> 00:31:39,089 But the Earth is a hundred times as old as that. 410 00:31:40,732 --> 00:31:42,427 And in that amount of time, 411 00:31:42,500 --> 00:31:45,594 our entire planet has been transformed. 412 00:31:49,340 --> 00:31:51,240 From the time the Earth cooled, 413 00:31:51,309 --> 00:31:54,244 its rocky crust has always been on the move. 414 00:31:56,281 --> 00:32:00,911 Oceans and mountain ranges have been and gone. 415 00:32:06,391 --> 00:32:10,157 Our planet today is just a snapshot in time. 416 00:32:12,397 --> 00:32:16,265 250 million years ago, the globe was very different. 417 00:32:19,304 --> 00:32:22,967 It was time that created the continents we recognise today. 418 00:32:25,076 --> 00:32:27,704 And time will continue to transform the Earth. 419 00:32:33,718 --> 00:32:38,553 But time has been crucial to another unique and extraordinary journey. 420 00:32:42,560 --> 00:32:43,584 Life. 421 00:32:46,998 --> 00:32:50,195 We are part of the most extraordinary story of all 422 00:32:50,935 --> 00:32:54,530 part of the incredible diversity of life on our planet. 423 00:32:59,010 --> 00:33:02,275 So what is ourjourney through time? 424 00:33:06,751 --> 00:33:11,415 What I find remarkable is the fact that this journey is imprinted in me. 425 00:33:11,956 --> 00:33:14,186 My body is like a museum. 426 00:33:14,425 --> 00:33:17,223 My face, my features, my arms, my legs, 427 00:33:17,295 --> 00:33:19,786 all of them bear the scars of evolution. 428 00:33:20,331 --> 00:33:23,994 So if I could peer into my DNA, into my body, 429 00:33:24,635 --> 00:33:26,626 I could perhaps retrace the steps 430 00:33:26,704 --> 00:33:29,400 taken by my ancestors thousands of years ago. 431 00:33:29,807 --> 00:33:32,469 I could take my own journey through time. 432 00:33:37,915 --> 00:33:41,681 All of these marks of time are catalogued in my DNA, 433 00:33:42,286 --> 00:33:44,880 logged in every one of my cells. 434 00:33:46,858 --> 00:33:48,553 One part of my DNA, 435 00:33:48,626 --> 00:33:50,594 mitochondrial DNA, 436 00:33:50,661 --> 00:33:53,027 is the key to tracing my ancestry. 437 00:33:53,698 --> 00:33:58,294 This DNA links me to all the mothers of my past. 438 00:33:58,836 --> 00:34:03,239 How and when I became a Japanese American living in the 21st century 439 00:34:03,841 --> 00:34:06,571 somehow is all encoded right here. 440 00:34:09,280 --> 00:34:12,044 I'm sending it to a special lab in Cambridge. 441 00:34:19,957 --> 00:34:21,720 Geneticist Peter Forster 442 00:34:21,993 --> 00:34:26,987 has created a global map of human ancestry, all based on DNA. 443 00:34:30,034 --> 00:34:32,628 By checking my sample against his database, 444 00:34:33,037 --> 00:34:34,868 I'm hoping that he'll be able to find out 445 00:34:34,939 --> 00:34:37,407 where my ancient forebears came from. 446 00:34:39,644 --> 00:34:42,545 I've come to London to see what Peter's found. 447 00:34:42,914 --> 00:34:44,643 I've been looking forward to this moment. 448 00:34:44,715 --> 00:34:46,842 Hi Michio, pleased to meet you. I'm Peter Forster. 449 00:34:46,918 --> 00:34:47,680 Hi Reary. How do you do? 450 00:34:47,919 --> 00:34:48,977 Do take a seat. 451 00:34:49,053 --> 00:34:50,452 Sure. So exciting. 452 00:34:50,888 --> 00:34:53,049 So, the moment of truth. 453 00:34:53,157 --> 00:34:54,454 What we've done to you is 454 00:34:54,525 --> 00:34:56,959 we've determined your mitochondrial DNA sequence. 455 00:34:57,028 --> 00:35:00,623 We can then trace your maternal ancestry back over generations. 456 00:35:00,698 --> 00:35:03,064 I say, I think my mother would be delighted to know this too. 457 00:35:04,135 --> 00:35:06,433 The interesting thing is that in Japan 458 00:35:06,504 --> 00:35:10,440 we only have about three hits in a sample size of over a thousand. 459 00:35:10,508 --> 00:35:11,600 That's unusual, right. 460 00:35:11,676 --> 00:35:13,644 Yeah, it's not a very usual lineage, in other words. 461 00:35:13,711 --> 00:35:18,045 Yeah. Um, it's interesting to see that you have cousins, 462 00:35:18,249 --> 00:35:19,614 distant cousins - 463 00:35:19,884 --> 00:35:21,408 - er, quite far away - 464 00:35:21,853 --> 00:35:23,582 - in er, and around Tibet. 465 00:35:23,654 --> 00:35:24,484 Is that right? 466 00:35:24,589 --> 00:35:26,250 Your maternal lineage M9, 467 00:35:26,691 --> 00:35:30,491 has its highest frequency in Tibet of the areas studied so far. 468 00:35:31,662 --> 00:35:33,220 Well, that's amazing, uh? 469 00:35:33,297 --> 00:35:34,594 Who - who'd have thought? 470 00:35:34,665 --> 00:35:35,222 Yeah. 471 00:35:39,003 --> 00:35:41,665 So life's full of surprises. 472 00:35:42,206 --> 00:35:46,267 I'm a Japanese American Tibetan living in New York. 473 00:35:47,478 --> 00:35:50,311 In fact, the same DNA connects us all, 474 00:35:51,249 --> 00:35:54,912 back to the very first modern humans that evolved in Africa 475 00:35:55,186 --> 00:35:57,677 over a hundred thousand years ago. 476 00:36:00,291 --> 00:36:01,918 But what about before that? 477 00:36:07,932 --> 00:36:12,528 This reorganisation of DNA lies at the heart of evolution. 478 00:36:18,643 --> 00:36:21,544 Ever since people began to carefully look at rocks 479 00:36:22,046 --> 00:36:23,343 they've found inside them 480 00:36:23,414 --> 00:36:27,111 the remains of creatures embedded inside their layers. 481 00:36:27,485 --> 00:36:31,148 I like to think of this as being a time capsule written in stone. 482 00:36:31,789 --> 00:36:34,986 Now, the story of life is written in these fossils. 483 00:36:35,326 --> 00:36:36,657 With specimens like these, 484 00:36:36,928 --> 00:36:40,864 science has been able to piece together life's journey through time. 485 00:36:42,466 --> 00:36:46,266 Because we can date the rocks, we can also date these trilobites. 486 00:36:47,238 --> 00:36:50,435 They lived over 500 million years ago, 487 00:36:50,775 --> 00:36:53,471 scuttling around the floor of some deep ocean. 488 00:36:57,014 --> 00:37:00,973 Fossils have allowed us to chart the evolutionary chain that led, 489 00:37:01,152 --> 00:37:02,676 by chance, to us. 490 00:37:03,821 --> 00:37:07,279 And it all began a staggeringly long time ago. 491 00:37:09,193 --> 00:37:10,990 Now the amazing thing is, 492 00:37:11,062 --> 00:37:13,257 when you look at older and older rock, 493 00:37:13,631 --> 00:37:15,895 you continue to see signs of life, 494 00:37:16,100 --> 00:37:18,660 all the way back to the earliest life forms, 495 00:37:18,836 --> 00:37:20,394 which are tiny little dots 496 00:37:20,471 --> 00:37:23,497 marking the presence of single-celled organisms. 497 00:37:23,975 --> 00:37:28,674 They date back to an incredible three and a half billion years ago, 498 00:37:29,013 --> 00:37:31,709 back to the very beginning of life's journey. 499 00:37:36,420 --> 00:37:39,321 To get a perspective of humanity's place in time, 500 00:37:39,757 --> 00:37:41,748 I'm making anotherjourney. 501 00:37:42,827 --> 00:37:44,852 Starting from the beginning of Earth time, 502 00:37:45,129 --> 00:37:47,359 right through to the present day. 503 00:37:54,171 --> 00:37:57,038 The first billion years of Earth time are lifeless. 504 00:38:00,678 --> 00:38:02,942 But then, no one knows exactly how, 505 00:38:03,247 --> 00:38:05,340 the first signs of life appear, 506 00:38:05,716 --> 00:38:08,116 three and a half billion years ago. 507 00:38:10,054 --> 00:38:12,614 These are our very first ancestors. 508 00:38:14,458 --> 00:38:16,585 Now for the next two and a half billion years, 509 00:38:16,661 --> 00:38:18,151 not much really happens. 510 00:38:19,263 --> 00:38:23,290 The Earth is dominated by single-celled organisms or bacteria. 511 00:38:23,868 --> 00:38:25,836 All they do is they live, 512 00:38:25,903 --> 00:38:29,771 they divide and they die, over and over and over again. 513 00:38:35,346 --> 00:38:36,779 As time passes, 514 00:38:36,847 --> 00:38:38,712 it's incredible just how long it takes 515 00:38:38,783 --> 00:38:42,014 before life shows any sign of change at all. 516 00:38:42,987 --> 00:38:48,482 It's not until 570 million years ago that something amazing happens. 517 00:38:53,164 --> 00:38:56,725 There's an explosion of new life forms in the world's oceans. 518 00:38:58,602 --> 00:39:01,765 These are the ancestors of all living animals 519 00:39:01,906 --> 00:39:05,205 fish, birds, even us. 520 00:39:06,844 --> 00:39:10,007 It isn't long before animals are everywhere on the planet. 521 00:39:30,668 --> 00:39:33,865 But it's not until around five million years ago 522 00:39:33,938 --> 00:39:36,998 that something remarkable happens in ourjourney. 523 00:39:38,509 --> 00:39:40,568 The first ape men appear. 524 00:39:42,079 --> 00:39:44,104 This is about when our ancestors 525 00:39:44,181 --> 00:39:47,048 first left the jungles and forests of Africa 526 00:39:47,118 --> 00:39:49,678 to live in the grasslands and Savannahs. 527 00:39:51,522 --> 00:39:54,423 That's when our ancestors begin to walk upright. 528 00:39:54,692 --> 00:39:55,886 This freed up the hand. 529 00:39:56,360 --> 00:39:59,329 The thumb, which was once used to swing in trees, 530 00:39:59,497 --> 00:40:02,193 can now be used to make tools and to grab things. 531 00:40:02,967 --> 00:40:05,435 That's when we begin to separate from the apes 532 00:40:05,503 --> 00:40:09,496 and begin our long journey to become modern humans. 533 00:40:10,808 --> 00:40:14,107 For us, it still seems a long, long journey 534 00:40:14,178 --> 00:40:16,043 from ape men to modern humans. 535 00:40:17,014 --> 00:40:21,644 But in the time span of life of Earth it's a mere stroll in the park. 536 00:40:24,355 --> 00:40:28,086 Civilisations get going only a few thousand years ago. 537 00:40:30,494 --> 00:40:32,758 We're just one tiny part of life's 538 00:40:32,830 --> 00:40:35,890 three and a half billion year journey through time. 539 00:40:42,440 --> 00:40:45,341 When we stop to think about the vastness of time 540 00:40:45,409 --> 00:40:46,967 and life's journey through it, 541 00:40:47,178 --> 00:40:49,738 it makes us feel so insignificant. 542 00:40:53,083 --> 00:40:55,483 But it's also amazing that we're here at all, 543 00:40:55,986 --> 00:40:58,454 able to think about our place in time, 544 00:40:59,990 --> 00:41:02,015 and to realise that one day 545 00:41:02,092 --> 00:41:05,528 humanity and all our glories will be gone. 546 00:41:09,600 --> 00:41:11,568 Time erodes everything too. 547 00:41:12,002 --> 00:41:14,937 99.9 per cent of all species 548 00:41:15,005 --> 00:41:17,735 that have ever lived on the Earth are now extinct. 549 00:41:18,142 --> 00:41:20,542 And one day we too may be erased. 550 00:41:21,011 --> 00:41:24,708 Our new perspective on the vastness of Earth history 551 00:41:24,782 --> 00:41:27,649 teaches us that live is very transient. 552 00:41:27,985 --> 00:41:31,614 When and how we may meet our end nobody knows, 553 00:41:32,156 --> 00:41:33,714 but evolution teaches us 554 00:41:33,791 --> 00:41:37,488 that one day the human race too will die out. 555 00:41:42,399 --> 00:41:46,665 So how far might humanity stretch into the future? 556 00:41:47,771 --> 00:41:49,568 It's impossible to tell for sure. 557 00:41:50,641 --> 00:41:53,201 But that doesn't stop us from imagining. 558 00:42:00,518 --> 00:42:03,316 One day, 7,000 years from now, 559 00:42:03,521 --> 00:42:08,515 an explorer stumbles into a cave deep inside a mountain in Nevada. 560 00:42:17,501 --> 00:42:20,095 He might find something extraordinary. 561 00:42:22,840 --> 00:42:25,570 It's a clock, unlike any ever built. 562 00:42:27,711 --> 00:42:31,078 Designed to run for ten thousand years. 563 00:42:31,815 --> 00:42:33,783 I imagine all the time 564 00:42:34,184 --> 00:42:37,017 an archaeologist discovering it thousands of years from now. 565 00:42:40,758 --> 00:42:43,886 Its creator, Danny Hillis, is an inventor. 566 00:42:44,862 --> 00:42:46,329 To conceive this clock, 567 00:42:46,397 --> 00:42:49,889 he had to ponder a future beyond our civilisation. 568 00:42:50,334 --> 00:42:54,202 I've come to realise there's no way I can possibly plan for what 569 00:42:54,271 --> 00:42:56,831 people are going to be like ten thousand years from now. 570 00:42:57,508 --> 00:42:59,567 Will I relate to them? Will they look like me? 571 00:43:00,244 --> 00:43:01,506 Will they be my descendents? 572 00:43:01,579 --> 00:43:05,276 Will they be from some other part of the Earth or some other planet? 573 00:43:05,349 --> 00:43:07,476 It starts raising a whole bunch of questions 574 00:43:07,551 --> 00:43:08,882 that you don't normally think about. 575 00:43:11,288 --> 00:43:13,882 The mechanics of the clock will be on display 576 00:43:14,024 --> 00:43:17,926 so that any people of the future can see exactly how it works. 577 00:43:22,633 --> 00:43:25,466 Danny's used the natural cycles of the planets 578 00:43:25,603 --> 00:43:28,128 as a universal language of time. 579 00:43:30,107 --> 00:43:32,166 He's reaching across time 580 00:43:32,409 --> 00:43:35,310 to speak to any civilisation that might follow us. 581 00:43:36,046 --> 00:43:38,606 What I want to do is say to the people of the future, 582 00:43:38,682 --> 00:43:40,741 well we did see, even when - 583 00:43:40,818 --> 00:43:43,753 we were going through that crazy thing that happened around 584 00:43:43,954 --> 00:43:46,752 the year 2000, a few centuries around it, 585 00:43:47,191 --> 00:43:49,785 even then we realised we were part of something 586 00:43:49,860 --> 00:43:51,953 larger that lasted a longer time. 587 00:43:55,499 --> 00:43:58,161 But even Danny's clock at 10,000 years 588 00:43:58,235 --> 00:44:00,294 is nothing in Earth's timescale. 589 00:44:02,306 --> 00:44:04,866 So what is our ultimate future? 590 00:44:09,613 --> 00:44:12,207 When will our Earth's time be over? 591 00:44:15,919 --> 00:44:20,015 The answer depends on an understanding not of life or the Earth, 592 00:44:20,391 --> 00:44:21,688 but of our sun. 593 00:44:30,634 --> 00:44:31,794 I'm in Arizona, 594 00:44:32,236 --> 00:44:35,501 on top of the biggest solar telescope in the world. 595 00:44:38,609 --> 00:44:43,012 It projects the largest live image of our sun that I'm ever likely to see. 596 00:45:00,497 --> 00:45:04,831 I have never seen the sun like this before, in its full glory. 597 00:45:04,902 --> 00:45:06,460 This is fantastic. 598 00:45:06,537 --> 00:45:08,061 The clarity, the size. 599 00:45:08,305 --> 00:45:10,671 And over here you can see a sunspot, 600 00:45:10,741 --> 00:45:14,142 representing a cooler storm on the surface of the sun. 601 00:45:14,812 --> 00:45:16,803 This is truly magnificent. 602 00:45:21,185 --> 00:45:25,417 Our source of light and heat, the sun powers our planet. 603 00:45:26,290 --> 00:45:28,850 Without it, life couldn't exist. 604 00:45:32,796 --> 00:45:35,594 But our sun will not be around forever, 605 00:45:36,166 --> 00:45:39,624 and when the sun dies the Earth will die too. 606 00:45:42,573 --> 00:45:43,904 In the 1930s, 607 00:45:43,974 --> 00:45:45,202 scientists speculated 608 00:45:45,275 --> 00:45:49,644 that the sun was a gigantic nuclear furnace burning up hydrogen. 609 00:45:50,114 --> 00:45:53,675 In fact, if you knew the total amount of sunlight that fell upon the Earth, 610 00:45:53,884 --> 00:45:55,078 you could even estimate 611 00:45:55,152 --> 00:45:58,280 how fast the sun was burning up its nuclear fuel. 612 00:45:58,555 --> 00:46:01,820 You could even calculate when the sun would die. 613 00:46:02,459 --> 00:46:03,892 But that was just a theory. 614 00:46:04,962 --> 00:46:08,295 Until the 1st November 1952. 615 00:46:13,537 --> 00:46:15,004 On an island in the Pacific, 616 00:46:15,072 --> 00:46:18,906 the most powerful bomb in human history was being tested. 617 00:46:21,445 --> 00:46:22,707 For the first time, 618 00:46:22,780 --> 00:46:24,611 by fusing hydrogen atoms, 619 00:46:24,681 --> 00:46:27,343 scientists were duplicating the very process 620 00:46:27,417 --> 00:46:29,510 that drives the sun's furnace. 621 00:46:33,056 --> 00:46:35,251 In some sense those hydrogen bombs 622 00:46:35,325 --> 00:46:38,226 were like a piece of the sun placed on the Earth. 623 00:46:38,829 --> 00:46:39,989 They confirmed the theory. 624 00:46:40,497 --> 00:46:44,058 We now knew with certainty when the sun would die. 625 00:46:44,601 --> 00:46:46,398 The sun is a middle aged star. 626 00:46:47,004 --> 00:46:49,564 It's consumed about half its nuclear fuel, 627 00:46:50,140 --> 00:46:53,303 and it will die in five billion years. 628 00:46:53,877 --> 00:46:54,844 That's a certainty. 629 00:46:55,379 --> 00:46:57,040 That's a law of physics. 630 00:47:03,453 --> 00:47:07,856 We've seen the birth of Earth time, 4.6 billion years ago. 631 00:47:09,593 --> 00:47:14,189 And now we know the end, in another five billion years. 632 00:47:15,833 --> 00:47:18,563 The Earth is halfway through its life. 633 00:47:20,771 --> 00:47:24,298 We have at last found our place in time. 634 00:47:25,742 --> 00:47:29,041 Just a tiny moment in our planet's great story, 635 00:47:29,947 --> 00:47:33,110 a transient fragment doomed to pass. 636 00:47:35,686 --> 00:47:39,520 But maybe, just maybe, we can escape. 637 00:47:40,791 --> 00:47:41,723 When I was a kid, 638 00:47:41,792 --> 00:47:43,657 I used to read a lot of science fiction 639 00:47:43,727 --> 00:47:46,423 because it would take me to a world of fantasy and adventure. 640 00:47:46,663 --> 00:47:48,426 But in my own lifetime 641 00:47:48,632 --> 00:47:51,192 I've seen many of these fantasies become reality. 642 00:47:51,468 --> 00:47:53,868 We've seen the beginning of space travel, 643 00:47:53,937 --> 00:47:55,336 genetic manipulation, 644 00:47:55,405 --> 00:47:57,965 the computer revolution and artificial intelligence. 645 00:47:58,208 --> 00:48:03,475 So I believe that the human creative spirit is truly limitless. 646 00:48:04,047 --> 00:48:06,345 And I believe that perhaps our technology 647 00:48:06,416 --> 00:48:08,543 may insulate us from extinction, 648 00:48:08,719 --> 00:48:12,917 elevate our human culture to heights that we've never seen before, 649 00:48:12,990 --> 00:48:16,289 and allow us to enter a new epic of time, 650 00:48:16,560 --> 00:48:19,495 in which we could continue our remarkable journey.