1 00:00:06,000 --> 00:00:12,074 Advertise your product or brand here contact www.OpenSubtitles.org today 2 00:02:08,045 --> 00:02:10,756 Which came first... 3 00:02:10,881 --> 00:02:12,883 the chicken or the egg? 4 00:02:16,887 --> 00:02:19,181 Did the universe have a beginning... 5 00:02:19,306 --> 00:02:22,392 and if so, what happened before then? 6 00:02:26,772 --> 00:02:29,733 Where did the universe come from... 7 00:02:29,858 --> 00:02:31,985 and where is it going? 8 00:03:03,767 --> 00:03:07,062 Luck. Luck. Well... 9 00:03:07,187 --> 00:03:09,773 we have been very lucky... 10 00:03:09,898 --> 00:03:13,026 I mean, my family and Stephen and everybody. 11 00:03:13,151 --> 00:03:16,113 You have your disasters, but the point is that we have survived. 12 00:03:16,280 --> 00:03:18,615 Everybody has disasters, and yet some people disappear... 13 00:03:18,782 --> 00:03:20,617 and are never seen again. 14 00:03:32,963 --> 00:03:35,757 Flying bombs are very alarming. 15 00:03:35,883 --> 00:03:37,926 They came buzzing over... 16 00:03:38,051 --> 00:03:39,970 and then they would cut out. 17 00:03:41,805 --> 00:03:44,600 And when you heard the bang, you knew it wasn't you... 18 00:03:44,725 --> 00:03:47,019 so you went back to your meal or whatever. 19 00:03:47,144 --> 00:03:50,147 But one did fall quite close to our house... 20 00:03:50,272 --> 00:03:52,691 and it blew the back windows out... 21 00:03:52,816 --> 00:03:56,320 so that the glass was sticking dagger points all out of the opposite wall. 22 00:03:59,656 --> 00:04:01,825 When Stephen was born, we decided... 23 00:04:01,992 --> 00:04:04,369 he'd better be born in Oxford. 24 00:04:04,494 --> 00:04:06,663 So while I was staying in the hospital... 25 00:04:07,706 --> 00:04:10,334 I went to Blackwell's in Oxford... 26 00:04:10,459 --> 00:04:13,462 and I bought an astronomical atlas. 27 00:04:14,922 --> 00:04:17,382 One of my sisters-in-law said... 28 00:04:17,508 --> 00:04:20,344 "This is a very prophetic thing for you to have done." 29 00:04:26,350 --> 00:04:28,477 How real is time? 30 00:04:29,853 --> 00:04:32,439 Will it ever come to an end? 31 00:04:35,859 --> 00:04:37,986 Where does the difference... 32 00:04:38,111 --> 00:04:41,198 between the past and the future come from? 33 00:04:43,367 --> 00:04:45,702 Why do we remember the past... 34 00:04:45,869 --> 00:04:47,955 but not the future? 35 00:04:52,543 --> 00:04:54,378 I can remember the day... 36 00:04:54,545 --> 00:04:58,507 when we traveled through London and the blackout was over. 37 00:05:02,344 --> 00:05:05,347 And the trains, instead of being shut in... 38 00:05:05,472 --> 00:05:08,016 by blinds so that you just traveled in a train... 39 00:05:08,141 --> 00:05:10,227 we were coming over one of the bridges... 40 00:05:10,394 --> 00:05:13,730 and all the lights... well, such lights as were left... 41 00:05:13,897 --> 00:05:17,192 were on in London, but it was also a completely starry night... 42 00:05:17,317 --> 00:05:20,112 and you could see the light. It was beautiful. 43 00:05:24,533 --> 00:05:29,079 I remember we all used to lie on the grass, looking straight up through a telescope... 44 00:05:29,246 --> 00:05:32,416 and seeing the wonders of the stars. 45 00:05:32,541 --> 00:05:36,086 Stephen always had a strong sense of wonder... 46 00:05:36,253 --> 00:05:39,423 and I could see that the stars would draw him... 47 00:05:39,590 --> 00:05:41,508 and further than the stars. 48 00:05:44,219 --> 00:05:47,055 I was born exactly 300 years... 49 00:05:47,181 --> 00:05:49,600 after the death of Galileo. 50 00:05:52,519 --> 00:05:56,273 I estimate that about 200,000 other babies... 51 00:05:56,440 --> 00:05:58,901 were also born that day. 52 00:06:01,278 --> 00:06:03,405 I don't know whether any of them... 53 00:06:03,530 --> 00:06:05,782 was later interested in astronomy. 54 00:06:09,494 --> 00:06:11,371 My first memory is of Isobel... 55 00:06:11,496 --> 00:06:14,291 pushing a rather antiquated... 56 00:06:14,416 --> 00:06:17,127 carriage-built pram along North Road... 57 00:06:17,294 --> 00:06:19,796 with Stephen and Mary in it... 58 00:06:19,922 --> 00:06:22,424 sort of looking very large... 59 00:06:22,549 --> 00:06:26,720 because they had large heads and pink cheeks, and they were very noticeable. 60 00:06:26,845 --> 00:06:30,140 They all looked different from ordinary people. 61 00:06:32,100 --> 00:06:35,896 I can remember visiting the Hawking home... 62 00:06:36,021 --> 00:06:37,814 oh, several times. 63 00:06:38,065 --> 00:06:41,693 It was the sort of place where, if invited to stay to supper... 64 00:06:41,818 --> 00:06:43,862 you might, uh... 65 00:06:43,987 --> 00:06:46,198 be allowed to have your conversation with Stephen... 66 00:06:46,323 --> 00:06:49,117 but the rest of the family would be sitting... 67 00:06:49,243 --> 00:06:51,453 at the table reading a book... 68 00:06:51,578 --> 00:06:55,082 a behavior which was not really approved of in my circle... 69 00:06:55,207 --> 00:06:57,251 but which was tolerated from the Hawkings... 70 00:06:57,376 --> 00:06:59,545 because they were recognized to be... 71 00:06:59,670 --> 00:07:03,090 very eccentric, highly intelligent... 72 00:07:03,215 --> 00:07:05,217 very clever people... 73 00:07:05,342 --> 00:07:08,011 but still a bit odd. 74 00:07:09,429 --> 00:07:13,475 My impression of the Hawking family was that they were all like that... 75 00:07:13,600 --> 00:07:15,853 except for Stephen, who seemed to be... 76 00:07:16,019 --> 00:07:18,105 the only normal member of the family. 77 00:07:20,899 --> 00:07:23,485 Stephen used to reckon he knew, I think it was... 78 00:07:23,610 --> 00:07:27,155 11 ways of getting into the house, and I could only find ten. 79 00:07:28,532 --> 00:07:30,951 I'm not sure where the other way was. 80 00:07:32,452 --> 00:07:36,331 On the north side of the house was a bicycle shed. 81 00:07:36,456 --> 00:07:39,960 It had a door at the front and a door at the back. 82 00:07:40,085 --> 00:07:43,964 Above that, there was a window into the L-shaped room... 83 00:07:45,507 --> 00:07:48,677 and at the front you could get sort of around the corner... 84 00:07:48,802 --> 00:07:51,221 onto the roof... 85 00:07:51,346 --> 00:07:54,057 and from that level... 86 00:07:54,183 --> 00:07:56,226 you could get onto the main roof. 87 00:07:57,728 --> 00:07:59,479 I think one of the ways... 88 00:07:59,605 --> 00:08:01,899 Stephen could get in was on the main roof. 89 00:08:04,985 --> 00:08:08,030 As I say, he was a much better climber than I was. 90 00:08:10,532 --> 00:08:13,118 I still didn't know what the 11th one was. 91 00:08:17,247 --> 00:08:19,750 Before the 20th century... 92 00:08:19,875 --> 00:08:24,004 it was thought that the universe had existed forever... 93 00:08:24,129 --> 00:08:27,758 or had been created at some time in the past... 94 00:08:27,925 --> 00:08:30,761 more or less as we observe it today. 95 00:08:32,971 --> 00:08:36,099 People found comfort in the thought... 96 00:08:36,225 --> 00:08:39,061 that even though they may grow old and die... 97 00:08:39,186 --> 00:08:42,648 the universe was eternal and unchanging. 98 00:08:45,192 --> 00:08:48,779 I gave up playing games with Stephen... 99 00:08:50,113 --> 00:08:53,992 oh, when he was ill that time when he was about 12... 100 00:08:54,117 --> 00:08:56,870 because he started taking games terribly seriously. 101 00:08:57,955 --> 00:09:00,791 We had Monopoly... 102 00:09:00,916 --> 00:09:02,918 and first of all... 103 00:09:03,043 --> 00:09:07,005 the Monopoly board sprang railways going across it... 104 00:09:07,130 --> 00:09:09,299 to add to the complications... 105 00:09:09,466 --> 00:09:12,261 and then Monopoly just wasn't adaptable enough. 106 00:09:12,386 --> 00:09:15,264 He ended up with a fearful game called Dynasty... 107 00:09:16,390 --> 00:09:19,601 which, as far as I can make out... I never played it... 108 00:09:19,726 --> 00:09:22,813 went on forever because there was no way of ending it. 109 00:09:23,272 --> 00:09:26,817 It was almost a substitute for living, as far as I could make out. 110 00:09:26,984 --> 00:09:29,486 It took hours and hours and hours. 111 00:09:29,903 --> 00:09:31,947 I thought it was a perfectly terrible game. 112 00:09:32,072 --> 00:09:34,825 I couldn't imagine anyone getting taken up with that. 113 00:09:34,950 --> 00:09:37,744 But Stephen always had a very complicated mind... 114 00:09:37,870 --> 00:09:39,705 and I felt as much as anything... 115 00:09:39,830 --> 00:09:42,332 it was the complication of it that appealed to him. 116 00:09:44,418 --> 00:09:47,671 When I was in high school, I learned that light... 117 00:09:47,796 --> 00:09:51,175 from distant galaxies was shifted to the red. 118 00:09:53,093 --> 00:09:56,513 This meant that they were moving away from us... 119 00:09:56,638 --> 00:09:58,974 and that the universe was expanding. 120 00:10:00,350 --> 00:10:02,519 But I didn't believe it. 121 00:10:06,023 --> 00:10:10,194 A static universe seemed much more natural. 122 00:10:11,570 --> 00:10:13,655 It could have existed... 123 00:10:13,780 --> 00:10:17,034 and could continue to exist forever. 124 00:10:20,621 --> 00:10:23,040 We were discussing the possibility... 125 00:10:23,165 --> 00:10:26,126 of the spontaneous generation of life... 126 00:10:26,251 --> 00:10:29,713 and I think that Stephen made a remark... 127 00:10:29,838 --> 00:10:32,132 which indicated not only that he'd thought of this... 128 00:10:32,257 --> 00:10:34,676 but he'd even also... 129 00:10:34,801 --> 00:10:37,012 come across some calculations... 130 00:10:37,137 --> 00:10:39,890 as to how long it might take. 131 00:10:40,307 --> 00:10:42,684 At that time, I think I made a comment... 132 00:10:42,809 --> 00:10:45,395 to one of my friends, John McClenahan... 133 00:10:45,562 --> 00:10:48,106 "I think that Stephen... 134 00:10:48,232 --> 00:10:50,651 will turn out to be unusually capable." 135 00:10:50,776 --> 00:10:53,278 I don't think I put it in quite those words... 136 00:10:53,403 --> 00:10:55,489 but I made some such remark to him... 137 00:10:55,614 --> 00:10:58,408 and he disagreed. 138 00:10:58,534 --> 00:11:01,161 And so we made a bet on the subject. 139 00:11:01,286 --> 00:11:03,247 In our childish way, we bet... 140 00:11:03,372 --> 00:11:06,041 a bag of sweets on the issue. 141 00:11:06,375 --> 00:11:10,587 And incidentally, I reckon that my bet has come correct... 142 00:11:10,754 --> 00:11:12,965 and I think I'm entitled to payment... 143 00:11:13,090 --> 00:11:15,843 which has not yet been made. 144 00:11:19,096 --> 00:11:21,431 The expansion of the universe... 145 00:11:21,557 --> 00:11:23,767 suggested the possibility... 146 00:11:23,934 --> 00:11:26,019 that the universe had a beginning... 147 00:11:26,144 --> 00:11:28,438 at some time in the past. 148 00:11:30,399 --> 00:11:34,611 The point at which the universe may have started out... 149 00:11:34,736 --> 00:11:37,322 became known as the Big Bang. 150 00:11:45,080 --> 00:11:47,791 The first year he was at St. Albans School... 151 00:11:47,916 --> 00:11:52,379 he came, I think, third from the bottom. 152 00:11:52,504 --> 00:11:54,506 I said, "Well, Stephen... 153 00:11:54,631 --> 00:11:57,968 do you really have to be as far down as that?" 154 00:11:58,093 --> 00:11:59,970 And he said, "Well... 155 00:12:00,137 --> 00:12:02,598 a lot of other people didn't do much better." 156 00:12:02,723 --> 00:12:04,808 He was quite unconcerned. 157 00:12:06,810 --> 00:12:08,979 Somehow he was always recognized... 158 00:12:09,104 --> 00:12:10,981 as being very bright... 159 00:12:12,149 --> 00:12:15,819 and in fact they gave him the Divinity Prize one year. 160 00:12:15,944 --> 00:12:19,156 That was not surprising because his father used to read him... 161 00:12:19,323 --> 00:12:21,366 Bible stories from a very early age... 162 00:12:21,491 --> 00:12:23,660 and he knew them all very well... 163 00:12:23,785 --> 00:12:26,330 and he was quite well-versed in religious things... 164 00:12:26,497 --> 00:12:30,250 although I don't think he makes a great deal of practice of it now. 165 00:12:30,584 --> 00:12:33,337 Everybody used to argue theology. 166 00:12:34,671 --> 00:12:37,841 That's a good, safe subject. 167 00:12:37,966 --> 00:12:40,761 You don't need any facts or... 168 00:12:40,886 --> 00:12:43,347 distracting things like that. 169 00:12:43,680 --> 00:12:46,141 If you go in for arguing... 170 00:12:48,018 --> 00:12:52,314 you know, debating... you can quite happily debate about anything... 171 00:12:52,439 --> 00:12:54,775 including theology... 172 00:12:54,900 --> 00:12:57,653 and the existence or otherwise of God. 173 00:13:00,864 --> 00:13:02,866 And then someone gets bored... 174 00:13:03,033 --> 00:13:06,203 or Journey Into Space comes on, or something like that... 175 00:13:06,328 --> 00:13:09,289 and the argument breaks up. 176 00:13:11,416 --> 00:13:13,544 In an unchanging universe... 177 00:13:13,669 --> 00:13:17,256 one can imagine that God created the universe... 178 00:13:17,381 --> 00:13:20,884 at literally any time in the past. 179 00:13:21,969 --> 00:13:24,221 On the other hand... 180 00:13:24,388 --> 00:13:26,723 if the universe is expanding... 181 00:13:26,890 --> 00:13:29,101 there may be physical reasons... 182 00:13:29,226 --> 00:13:31,854 why there had to be a beginning. 183 00:13:33,397 --> 00:13:37,234 An expanding universe does not preclude a creator... 184 00:13:37,359 --> 00:13:39,236 but it does place limits... 185 00:13:39,361 --> 00:13:42,781 on when he might have carried out his job. 186 00:13:46,910 --> 00:13:49,621 When the family went to India... 187 00:13:49,746 --> 00:13:53,250 it was arranged that Stephen should come and live with us for a year. 188 00:13:54,418 --> 00:13:56,753 He decided it would be nice... 189 00:13:56,879 --> 00:13:59,256 that we should have... 190 00:13:59,423 --> 00:14:01,800 Scottish dancing in the evening. 191 00:14:01,925 --> 00:14:04,678 Mind you, this was quite an ordinary house... 192 00:14:04,803 --> 00:14:07,973 but we had rather a lot of room and a large hall... 193 00:14:08,098 --> 00:14:11,768 and so we bought some records... 194 00:14:11,935 --> 00:14:15,814 and a book about what to do... 195 00:14:15,939 --> 00:14:18,775 and Stephen took charge. 196 00:14:18,942 --> 00:14:22,821 And he insisted you put on a jacket and a tie. 197 00:14:22,946 --> 00:14:27,451 And then he was the master of the proceedings. 198 00:14:27,576 --> 00:14:29,786 And Stephen took it very seriously. 199 00:14:29,953 --> 00:14:32,289 But then he liked dancing, you see? 200 00:14:35,792 --> 00:14:39,129 There were four physicists in my year... 201 00:14:39,254 --> 00:14:41,131 Gordon Berry... 202 00:14:41,256 --> 00:14:43,133 Richard Bryan... 203 00:14:43,258 --> 00:14:45,135 Stephen... 204 00:14:45,260 --> 00:14:47,095 myself. 205 00:14:48,639 --> 00:14:51,892 I first remember Stephen... 206 00:14:52,017 --> 00:14:55,854 on an occasion when Gordon and I went up after dinner to his room... 207 00:14:55,979 --> 00:14:59,316 to try to find him. 208 00:14:59,483 --> 00:15:01,318 And Stephen was up there... 209 00:15:01,485 --> 00:15:03,820 with a crate of beer... 210 00:15:03,946 --> 00:15:06,156 slowly drinking his way through it. 211 00:15:07,241 --> 00:15:10,953 He was only 17. He couldn't legally go into a pub. 212 00:15:11,078 --> 00:15:13,956 He'd gone up to Oxford ridiculously early. 213 00:15:19,127 --> 00:15:22,130 We used to have what we called a gathering net. 214 00:15:23,715 --> 00:15:27,427 We used to organize a beer party and various things like that... 215 00:15:27,553 --> 00:15:30,722 to gather all these... collar as many freshman as we could get... 216 00:15:30,848 --> 00:15:32,891 to get them to join the Boat Club. 217 00:15:33,016 --> 00:15:36,186 And that's how we collected him, you see? 218 00:15:42,860 --> 00:15:45,654 But the question always with Stephen was... 219 00:15:46,738 --> 00:15:49,241 "Should we make him the cox of the first eight... 220 00:15:49,366 --> 00:15:52,035 or the second eight?" 221 00:15:52,161 --> 00:15:55,664 Well, coxes can be adventurous... 222 00:15:55,789 --> 00:15:59,459 and some coxes can be very steady people. 223 00:15:59,585 --> 00:16:02,671 He was rather an adventurous type. 224 00:16:04,214 --> 00:16:06,717 You never knew quite what he was going to do... 225 00:16:06,884 --> 00:16:08,802 when he went out with the crew. 226 00:16:13,891 --> 00:16:17,644 I think he used to bring his work with him into the boat sometimes. 227 00:16:17,769 --> 00:16:19,980 His sort of thinking gear was going... 228 00:16:20,105 --> 00:16:22,566 on different levels. 229 00:16:24,651 --> 00:16:29,072 We were asked to read chapter 10... 230 00:16:29,239 --> 00:16:32,075 in a book called Electricity and Magnetism... 231 00:16:32,242 --> 00:16:34,745 by Bleaney and Bleaney, an unlikely combination... 232 00:16:34,912 --> 00:16:36,997 a husband-and-wife team... 233 00:16:37,122 --> 00:16:40,375 and at the end of that chapter, there were 13 questions... 234 00:16:40,501 --> 00:16:44,004 all of them final honors questions. 235 00:16:44,129 --> 00:16:48,467 I discovered very rapidly that I couldn't do any of them. 236 00:16:48,592 --> 00:16:50,886 Richard and I worked together for the week... 237 00:16:51,011 --> 00:16:53,597 and we managed to do 1 1/2 questions... 238 00:16:53,764 --> 00:16:55,682 which we felt very proud of. 239 00:16:55,807 --> 00:16:57,768 Gordon refused all assistance... 240 00:16:57,893 --> 00:17:01,146 and managed to do one all by himself. 241 00:17:01,271 --> 00:17:04,024 Stephen, as always, hadn't even started... 242 00:17:04,149 --> 00:17:08,278 but the next morning, he went up to his rooms at 9:00... 243 00:17:09,488 --> 00:17:12,824 and we came back about 12:00, maybe five past 12:00... 244 00:17:12,950 --> 00:17:17,037 and down came Stephen, and we were in the college gateway, the lodge. 245 00:17:17,162 --> 00:17:20,791 "Ah, Hawking," I said, "how many have you managed to do, then?" 246 00:17:20,958 --> 00:17:24,795 "Well," he said, "I've only had time to do the first ten." 247 00:17:26,129 --> 00:17:30,425 I think at that point we realized that it's not just we weren't in the same street. 248 00:17:30,551 --> 00:17:32,636 We weren't on the same planet. 249 00:17:36,431 --> 00:17:38,475 I once calculated... 250 00:17:38,600 --> 00:17:41,603 that I did about 1,000 hours' work... 251 00:17:41,728 --> 00:17:45,148 in the three years I was at Oxford... 252 00:17:45,315 --> 00:17:47,985 an average of an hour a day. 253 00:17:48,944 --> 00:17:51,697 I am not proud of this lack of work. 254 00:17:51,822 --> 00:17:55,158 I am just describing my attitude at the time... 255 00:17:56,451 --> 00:18:00,455 an attitude that nothing was worth making an effort for. 256 00:18:04,042 --> 00:18:07,796 He used to produce his work every week for tutorial... 257 00:18:07,921 --> 00:18:11,175 and, as he never kept any notes... 258 00:18:11,341 --> 00:18:13,927 or papers or that sort of thing... 259 00:18:14,052 --> 00:18:18,515 on leaving my room, he would normally throw it in my wastepaper basket. 260 00:18:18,640 --> 00:18:22,853 And when he was with other undergraduates at the tutorial... 261 00:18:23,020 --> 00:18:25,522 and they saw this happen, they were absolutely horrified... 262 00:18:25,647 --> 00:18:29,067 'cause they thought, he did this work in probably half an hour... 263 00:18:29,193 --> 00:18:33,697 If they could have done it in a year, they wouldn't have thrown it in the wastepaper basket. 264 00:18:33,864 --> 00:18:36,283 They would've put it in a frame on their walls. 265 00:18:37,951 --> 00:18:40,204 Because of my lack of work... 266 00:18:40,370 --> 00:18:43,332 I had planned to get through the final exam... 267 00:18:43,457 --> 00:18:46,668 by doing problems in theoretical physics... 268 00:18:46,793 --> 00:18:51,548 and avoiding any questions that required factual knowledge. 269 00:18:53,467 --> 00:18:55,844 I didn't do very well. 270 00:18:57,387 --> 00:19:01,975 I was on the borderline between a first- and second-class degree... 271 00:19:02,100 --> 00:19:06,522 and I had to be interviewed to determine which I should get. 272 00:19:08,148 --> 00:19:11,318 They asked me about my future plans. 273 00:19:12,778 --> 00:19:16,240 I replied, if they gave me a first... 274 00:19:16,365 --> 00:19:18,534 I would go to Cambridge. 275 00:19:20,118 --> 00:19:22,412 If I only got a second... 276 00:19:22,579 --> 00:19:24,915 I would stay in Oxford. 277 00:19:26,625 --> 00:19:28,752 They gave me a first. 278 00:19:35,509 --> 00:19:38,637 I drove Stephen and his young brother... 279 00:19:38,762 --> 00:19:41,181 out to Woburn Park... 280 00:19:41,306 --> 00:19:43,308 and he climbed a tree. 281 00:19:43,433 --> 00:19:46,103 He was testing himself out, I think. I didn't realize. 282 00:19:46,228 --> 00:19:48,063 He did manage to climb a tree... 283 00:19:48,188 --> 00:19:51,233 and go along a branch of it and get himself down. 284 00:19:51,358 --> 00:19:54,820 I think he began to notice that his hands... 285 00:19:54,945 --> 00:19:57,573 were less useful than they had been... 286 00:19:57,698 --> 00:19:59,616 but he didn't tell us. 287 00:20:02,369 --> 00:20:04,872 Univ has these square staircases... 288 00:20:04,997 --> 00:20:07,666 which are round but they're square. 289 00:20:07,791 --> 00:20:10,711 It was just coming down from one of the rooms. 290 00:20:10,836 --> 00:20:14,381 Steve actually fell on the stairs coming downstairs... 291 00:20:14,506 --> 00:20:17,759 and kind of bounced all the way down to the bottom. 292 00:20:17,885 --> 00:20:22,222 I don't know if he lost consciousness, but he lost his memory. 293 00:20:23,640 --> 00:20:27,019 We took him to either my room or someone's room. 294 00:20:27,144 --> 00:20:29,605 The first question of course was, "Who am I?" 295 00:20:29,730 --> 00:20:32,149 We told him, "You're Steve Hawking." 296 00:20:32,274 --> 00:20:36,737 Right away he would ask again, "Who am I?" 297 00:20:36,862 --> 00:20:38,614 "Steve Hawking." 298 00:20:38,739 --> 00:20:42,534 Then, after a couple of minutes, he remembered he was Steve Hawking. 299 00:20:42,659 --> 00:20:45,871 Then we'd say, "Do you remember going down to the bar... 300 00:20:45,996 --> 00:20:48,332 and having a drink on Sunday night?" 301 00:20:48,499 --> 00:20:51,919 Or, "Do you remember coxing on the river on Monday?" 302 00:20:52,044 --> 00:20:54,421 And his memory came back gradually... 303 00:20:54,546 --> 00:20:58,133 until he could remember the previous day's events, and then the previous hour... 304 00:20:58,258 --> 00:21:02,179 and by the end of the two hours, he could remember everything. 305 00:21:02,304 --> 00:21:04,598 The question was, "Well, maybe you've lost... 306 00:21:04,723 --> 00:21:06,683 some of your mind because of this." 307 00:21:06,808 --> 00:21:10,979 And so Steve decided, "Well, I'll take the Mensa test." 308 00:21:11,104 --> 00:21:13,065 We said, "Of course you'll get in." 309 00:21:13,190 --> 00:21:16,777 But he came back delighted he was able to get into Mensa. 310 00:21:16,902 --> 00:21:18,862 Absolutely delighted. 311 00:21:29,873 --> 00:21:31,959 I felt that there were two areas... 312 00:21:32,084 --> 00:21:34,253 of theoretical physics... 313 00:21:34,378 --> 00:21:36,547 I might study at Cambridge. 314 00:21:38,757 --> 00:21:43,136 One was cosmology, the study of the very large. 315 00:21:45,848 --> 00:21:49,685 The other was elementary particles... 316 00:21:49,810 --> 00:21:52,396 the study of the very small. 317 00:21:54,064 --> 00:21:56,859 However, I thought elementary particles... 318 00:21:56,984 --> 00:21:58,652 were less attractive... 319 00:21:58,777 --> 00:22:01,822 because there was no proper theory. 320 00:22:03,115 --> 00:22:04,867 All they could do... 321 00:22:04,992 --> 00:22:08,078 was arrange the particles in families... 322 00:22:08,245 --> 00:22:10,164 like in botany. 323 00:22:12,916 --> 00:22:15,669 In cosmology, on the other hand... 324 00:22:15,794 --> 00:22:18,589 there was a well-defined theory... 325 00:22:18,755 --> 00:22:22,050 Einstein's general theory of relativity. 326 00:22:29,057 --> 00:22:31,268 It was a very cold year... 327 00:22:33,020 --> 00:22:37,691 and the ice on Verulamium Pond... 328 00:22:37,816 --> 00:22:40,277 it was frozen there... 329 00:22:40,444 --> 00:22:43,697 and we all went skating. 330 00:22:43,822 --> 00:22:46,366 And Stephen managed to skate fairly well... 331 00:22:46,492 --> 00:22:48,952 but then, he and I were close together. 332 00:22:49,119 --> 00:22:51,163 He wasn't skating in a very advanced way... 333 00:22:51,288 --> 00:22:54,166 but nor was I, if it comes to that. 334 00:22:54,291 --> 00:22:56,001 He fell... 335 00:22:56,126 --> 00:22:58,295 and he couldn't get up. 336 00:22:59,505 --> 00:23:03,091 So I took him to a café to warm up... 337 00:23:03,217 --> 00:23:05,719 and he told me then all about it. 338 00:23:07,179 --> 00:23:09,515 And it was diagnosed. 339 00:23:10,891 --> 00:23:13,936 I insisted on going to see his doctor... 340 00:23:14,061 --> 00:23:17,314 because it seemed to me however long you're going to live... 341 00:23:17,481 --> 00:23:19,775 there's probably something someone can do about it... 342 00:23:19,900 --> 00:23:22,861 at least anyhow to make things easier for people. 343 00:23:22,986 --> 00:23:25,405 I won't mention the doctor's name... 344 00:23:25,531 --> 00:23:29,201 but I got to see him at the London Clinic. 345 00:23:29,326 --> 00:23:32,996 He was rather surprised that I should bother to come 'round to see him. 346 00:23:33,121 --> 00:23:35,749 After all, I was only Stephen's mother. 347 00:23:35,874 --> 00:23:39,837 He was quite nice. He agreed to see me in a rather grand way. 348 00:23:39,962 --> 00:23:41,964 And he said, "Yes, it's all very sad. 349 00:23:42,089 --> 00:23:44,967 Brilliant young man cut off in the prime of his youth." 350 00:23:45,092 --> 00:23:47,594 But of course I said, "What can we do? 351 00:23:47,719 --> 00:23:49,638 What can we do to sort of... 352 00:23:49,763 --> 00:23:51,849 Can we get physiotherapy? 353 00:23:51,974 --> 00:23:55,185 Can we get anything like that that will help in any way?" 354 00:23:55,352 --> 00:23:57,396 He said, "Well, actually, no. 355 00:23:57,521 --> 00:24:00,524 There's nothing I can do, really. More or less, that's it." 356 00:24:04,194 --> 00:24:07,406 Shortly after my 21st birthday... 357 00:24:07,531 --> 00:24:10,367 I went into hospital for tests. 358 00:24:12,661 --> 00:24:15,497 They took a muscle sample from my arm... 359 00:24:15,622 --> 00:24:17,583 stuck electrodes into me... 360 00:24:17,708 --> 00:24:21,712 and injected some radiopaque fluid into my spine... 361 00:24:21,879 --> 00:24:24,715 and watched it going up and down with X-rays... 362 00:24:24,882 --> 00:24:27,009 as they tilted the bed. 363 00:24:29,136 --> 00:24:32,598 I was diagnosed as having ALS... 364 00:24:32,723 --> 00:24:35,642 amyotrophic lateral sclerosis... 365 00:24:35,767 --> 00:24:40,105 or motor neuron disease, as it is also known. 366 00:24:41,690 --> 00:24:44,067 The doctors could offer no cure... 367 00:24:44,234 --> 00:24:47,654 and gave me 2 1/2 years to live. 368 00:24:57,706 --> 00:25:00,918 I went into the graduates' common room... 369 00:25:01,084 --> 00:25:03,754 looking, really, for someone to have lunch with. 370 00:25:03,921 --> 00:25:07,132 There was nobody around that I particularly wished to have lunch with... 371 00:25:07,257 --> 00:25:09,051 and then Stephen walked through the door. 372 00:25:09,176 --> 00:25:12,763 I don't know what he was doing at Oxford. I've certainly forgotten now. 373 00:25:12,888 --> 00:25:16,433 And so Stephen generously went off... 374 00:25:16,558 --> 00:25:18,519 to buy the drinks... 375 00:25:18,644 --> 00:25:20,938 and brought them and put them on the table. 376 00:25:21,063 --> 00:25:23,357 And as he put his pint of beer down... 377 00:25:23,482 --> 00:25:25,275 he spilled it. 378 00:25:25,400 --> 00:25:27,611 I sort of said genially... 379 00:25:27,778 --> 00:25:31,073 "Oh, heavens. Drinking at this time of day!" 380 00:25:31,198 --> 00:25:35,619 He then told me he'd been in Addenbrooke's for three weeks... 381 00:25:35,786 --> 00:25:38,121 and they'd done a whole series of tests... 382 00:25:38,247 --> 00:25:40,916 and they'd decided... 383 00:25:41,041 --> 00:25:42,960 what was wrong with him. 384 00:25:43,085 --> 00:25:47,005 And he told me very straight and flat... 385 00:25:47,130 --> 00:25:49,716 that he was gradually going to lose... 386 00:25:49,842 --> 00:25:52,386 the use of his body... 387 00:25:52,511 --> 00:25:54,888 that eventually... 388 00:25:55,013 --> 00:25:58,141 only his heart and his lungs... 389 00:25:58,308 --> 00:26:01,687 would still be operating, and his brain... 390 00:26:01,812 --> 00:26:03,897 and that they'd told him that... 391 00:26:04,022 --> 00:26:08,277 eventually he would essentially have the body of a cabbage... 392 00:26:08,402 --> 00:26:11,780 but his mind would still be in perfect working order... 393 00:26:11,905 --> 00:26:15,492 and he would be unable to communicate with the rest of the world. 394 00:26:18,829 --> 00:26:22,040 My dreams at that time were rather disturbed. 395 00:26:24,126 --> 00:26:27,004 Before my condition had been diagnosed... 396 00:26:27,129 --> 00:26:29,840 I had been very bored with life. 397 00:26:31,592 --> 00:26:35,179 There had not seemed to be anything worth doing. 398 00:26:37,389 --> 00:26:40,350 But shortly after I came out of hospital... 399 00:26:40,517 --> 00:26:44,104 I dreamt that I was going to be executed. 400 00:26:45,355 --> 00:26:48,984 I suddenly realized there were a lot of worthwhile things... 401 00:26:49,109 --> 00:26:52,029 I could do if I were reprieved. 402 00:26:58,702 --> 00:27:03,040 I knew perfectly well that he had no faith... 403 00:27:03,165 --> 00:27:04,833 and... 404 00:27:05,876 --> 00:27:08,337 to me, that made it the more difficult... 405 00:27:08,462 --> 00:27:11,215 because you must ask yourself, "Why me? 406 00:27:11,381 --> 00:27:14,551 Why this? Why now?" 407 00:27:14,718 --> 00:27:18,138 But he just totally, flatly accepted... 408 00:27:18,263 --> 00:27:20,807 that this was what was going to happen to him. 409 00:27:20,933 --> 00:27:24,978 As far as I can gather, at that point he started to do some work. 410 00:27:26,897 --> 00:27:29,775 At first, there did not seem much point... 411 00:27:29,900 --> 00:27:31,944 in working at my research... 412 00:27:32,069 --> 00:27:34,821 because I didn't expect to live long enough... 413 00:27:34,947 --> 00:27:37,908 to finish my PhD. 414 00:27:39,117 --> 00:27:41,662 However, as time went by... 415 00:27:41,787 --> 00:27:44,248 the disease seemed to slow down. 416 00:27:46,250 --> 00:27:49,586 I began to understand general relativity... 417 00:27:49,753 --> 00:27:52,005 and made progress with my work. 418 00:27:54,174 --> 00:27:56,718 But what really made a difference was... 419 00:27:56,844 --> 00:28:01,098 I had got engaged to a girl called Jane Wilde. 420 00:28:02,724 --> 00:28:05,602 This gave me something to live for... 421 00:28:05,769 --> 00:28:08,605 but it also meant I had to get a job... 422 00:28:08,772 --> 00:28:11,024 if we were to get married. 423 00:28:13,068 --> 00:28:16,446 Stephen was already ill. Jane knew it. 424 00:28:16,572 --> 00:28:20,409 And it was another instance of Stephen's luck, you know... 425 00:28:20,534 --> 00:28:23,245 meeting the right person at the right time... 426 00:28:23,370 --> 00:28:28,542 because Stephen was very, very badly depressed... 427 00:28:28,667 --> 00:28:32,171 and he wasn't very much inclined to go on with his work. 428 00:28:32,296 --> 00:28:34,631 He'd been told he's only got 2 1/2 years. 429 00:28:34,756 --> 00:28:36,800 What can you do in that time? 430 00:28:36,967 --> 00:28:40,679 But meeting Jane really put him on his mettle... 431 00:28:40,804 --> 00:28:42,806 and he started to work. 432 00:28:45,601 --> 00:28:47,686 I wanted to understand... 433 00:28:47,811 --> 00:28:49,813 how the universe began. 434 00:28:52,065 --> 00:28:54,943 Einstein's theory of general relativity... 435 00:28:55,068 --> 00:28:57,946 showed that the universe was expanding. 436 00:28:59,490 --> 00:29:02,993 But there was no answer to the crucial question... 437 00:29:03,160 --> 00:29:05,704 "Must there have been a Big Bang... 438 00:29:05,829 --> 00:29:07,789 a beginning to time?" 439 00:29:09,833 --> 00:29:12,961 Then, in my third year at Cambridge... 440 00:29:13,086 --> 00:29:15,714 Roger Penrose made his discovery... 441 00:29:15,839 --> 00:29:18,467 about the death of stars. 442 00:29:19,927 --> 00:29:23,680 I remember talking to this friend, Ivor Robinson... 443 00:29:23,805 --> 00:29:27,142 and we were having this animated conversation... 444 00:29:27,267 --> 00:29:30,479 and then we had to cross a road... 445 00:29:30,604 --> 00:29:33,524 and as we crossed the road, of course, the conversation stopped... 446 00:29:33,649 --> 00:29:35,651 and then we got to the other side. 447 00:29:35,776 --> 00:29:38,403 Evidently, I had some idea crossing the road... 448 00:29:38,529 --> 00:29:42,533 but then the conversation started up, and it got completely blotted out of my mind. 449 00:29:42,658 --> 00:29:46,703 It was only later, after my friend had gone home... 450 00:29:46,829 --> 00:29:51,291 and I began to have this strange feeling of elation... 451 00:29:51,416 --> 00:29:53,252 feeling wonderful. 452 00:29:53,377 --> 00:29:57,714 I couldn't figure out why I should feel like that, so I went back over the day... 453 00:29:57,840 --> 00:30:01,051 thinking all possible things which might have contributed to such a feeling... 454 00:30:01,176 --> 00:30:04,054 and then gradually I unearthed this thought... 455 00:30:04,179 --> 00:30:06,181 which I'd had while crossing the street. 456 00:30:06,598 --> 00:30:09,393 Penrose announced this result... 457 00:30:09,560 --> 00:30:12,271 that when stars collapse indefinitely... 458 00:30:12,396 --> 00:30:14,439 they will become singular... 459 00:30:14,565 --> 00:30:17,943 as long as some very broad conditions are satisfied... 460 00:30:18,068 --> 00:30:20,821 that everybody would have regarded as reasonable. 461 00:30:20,946 --> 00:30:23,615 And I remember Stephen Hawking, who was then approaching... 462 00:30:23,740 --> 00:30:26,201 his third year as a research student, saying... 463 00:30:26,326 --> 00:30:28,412 "What very interesting results. 464 00:30:28,579 --> 00:30:30,706 I wonder whether they could be adapted... 465 00:30:30,831 --> 00:30:33,625 to understanding the origin of the universe." 466 00:30:33,750 --> 00:30:37,296 And what he had in mind, you see, was that if, just mentally... 467 00:30:37,421 --> 00:30:39,464 you reverse the sense of time... 468 00:30:39,590 --> 00:30:42,801 you can think of the expanding universe as a collapsing system. 469 00:30:42,926 --> 00:30:45,888 It's a bit like a very giant star collapsing. 470 00:30:47,097 --> 00:30:49,057 Roger Penrose proved... 471 00:30:49,183 --> 00:30:53,395 that a dying star, collapsing under its own gravity... 472 00:30:53,520 --> 00:30:57,191 eventually shrinks to a singularity... 473 00:30:57,316 --> 00:31:01,778 a point of infinite density and zero size. 474 00:31:04,615 --> 00:31:08,452 I realized that if I reversed the direction of time... 475 00:31:08,577 --> 00:31:11,622 so that the collapse became an expansion... 476 00:31:11,747 --> 00:31:13,582 I could prove that... 477 00:31:13,707 --> 00:31:15,792 the universe had a beginning. 478 00:31:19,505 --> 00:31:21,381 But my proof... 479 00:31:21,507 --> 00:31:25,135 based on Einstein's theory of general relativity... 480 00:31:25,260 --> 00:31:28,639 also showed that we cannot understand... 481 00:31:28,764 --> 00:31:31,141 how the universe began... 482 00:31:32,309 --> 00:31:36,438 because it showed that all scientific theories... 483 00:31:36,563 --> 00:31:39,983 including general relativity itself... 484 00:31:40,108 --> 00:31:43,737 break down at the beginning of the universe. 485 00:31:55,332 --> 00:31:57,167 We had this meeting... 486 00:31:57,334 --> 00:32:00,337 at the Institute of Space Physics in New York. 487 00:32:00,462 --> 00:32:03,382 I said, "Before we reach a final conclusion... 488 00:32:03,507 --> 00:32:06,218 we ought to throw into the pot... 489 00:32:06,343 --> 00:32:08,387 still another object... 490 00:32:08,512 --> 00:32:12,766 a gravitationally completely collapsed object. 491 00:32:12,891 --> 00:32:15,018 Well, after you've used the phrase... 492 00:32:15,143 --> 00:32:19,690 "a gravitationally completely collapsed object" ten times... 493 00:32:19,815 --> 00:32:22,901 you conclude you've got to get a better name. 494 00:32:23,026 --> 00:32:25,154 So that's when I switched... 495 00:32:25,279 --> 00:32:27,531 to the word "black hole". 496 00:32:27,990 --> 00:32:31,410 The word "black hole," which John Wheeler coined, suddenly caught on. 497 00:32:31,535 --> 00:32:34,788 Everybody adopted it, and from then on... 498 00:32:34,913 --> 00:32:37,749 people around the world... in Moscow... 499 00:32:37,875 --> 00:32:40,335 in America... 500 00:32:40,460 --> 00:32:42,337 in England and elsewhere... 501 00:32:42,462 --> 00:32:45,340 could know they were speaking about the same thing. 502 00:32:45,465 --> 00:32:48,552 And not only that, but suddenly... 503 00:32:48,677 --> 00:32:51,430 the whole range of concepts got through to the general public... 504 00:32:51,555 --> 00:32:54,474 and even science-fiction writers all of a sudden... 505 00:32:54,600 --> 00:32:56,560 could talk about it. 506 00:32:58,061 --> 00:33:00,480 Tonight, my friends... 507 00:33:00,606 --> 00:33:04,276 we stand on the brink of a feat unparalleled... 508 00:33:04,401 --> 00:33:06,445 in space exploration. 509 00:33:07,613 --> 00:33:09,740 If the data on my returning probe ship... 510 00:33:09,907 --> 00:33:12,284 matches my computerized calculations... 511 00:33:12,409 --> 00:33:16,038 I will travel where no man has dared to go. 512 00:33:17,247 --> 00:33:19,541 Into the black hole? 513 00:33:19,666 --> 00:33:21,251 In... 514 00:33:22,419 --> 00:33:24,087 through... 515 00:33:25,380 --> 00:33:27,257 and beyond. 516 00:33:29,009 --> 00:33:31,136 Why, that's crazy! 517 00:33:31,261 --> 00:33:33,764 Ha! Impossible! 518 00:33:36,433 --> 00:33:38,936 As a massive star contracts... 519 00:33:39,061 --> 00:33:41,480 its gravity becomes so strong... 520 00:33:41,605 --> 00:33:44,441 that light can no longer escape. 521 00:33:46,360 --> 00:33:49,571 The region from which nothing can escape... 522 00:33:49,696 --> 00:33:52,115 is called a black hole... 523 00:33:52,241 --> 00:33:55,536 and its boundary is called the event horizon. 524 00:33:58,247 --> 00:34:00,958 One might say of the event horizon... 525 00:34:01,124 --> 00:34:04,044 what Dante said of the entrance to hell... 526 00:34:05,587 --> 00:34:09,216 "Abandon all hope, ye who enter here." 527 00:34:13,762 --> 00:34:16,139 I was once asked to actually... 528 00:34:16,306 --> 00:34:18,475 be an adjudicator... 529 00:34:18,642 --> 00:34:22,479 on an essay of which the subject was... 530 00:34:22,604 --> 00:34:25,315 "How to fall through a black hole and live." 531 00:34:25,440 --> 00:34:28,527 Now, the problem I had was that I wouldn't know... 532 00:34:28,652 --> 00:34:30,654 how to give out the prize... 533 00:34:30,821 --> 00:34:34,158 because if I said, "That looks like a good essay"... 534 00:34:34,283 --> 00:34:37,161 the only real way of showing this was right... 535 00:34:37,327 --> 00:34:41,248 was to actually follow it, to do the experiment and fall in. 536 00:34:41,373 --> 00:34:43,333 But then, having fallen in... 537 00:34:43,500 --> 00:34:46,587 I would assume taking the person who wrote the essay with you... 538 00:34:46,712 --> 00:34:49,923 the question would be, how do you tell the rest of the world? 539 00:34:50,048 --> 00:34:52,634 Do you take the prize in that you give to them... 540 00:34:52,759 --> 00:34:55,429 and what do they do with it when they get to the center? 541 00:34:56,513 --> 00:34:58,640 Believe me... 542 00:34:58,765 --> 00:35:01,685 I've been waiting a long time for someone like you... 543 00:35:01,810 --> 00:35:03,687 to record this moment. 544 00:35:03,812 --> 00:35:06,440 Thank you, Doctor. 545 00:35:06,565 --> 00:35:08,275 Then I'm ready. 546 00:35:09,693 --> 00:35:13,405 Ready to embark on man's greatest journey. 547 00:35:13,530 --> 00:35:15,741 Certainly his riskiest. 548 00:35:15,866 --> 00:35:18,869 The risk is incidental compared to... 549 00:35:18,994 --> 00:35:23,081 the possibility to possess the great truth of the unknown. 550 00:35:23,207 --> 00:35:25,375 There... 551 00:35:25,501 --> 00:35:28,378 long-cherished laws of nature... 552 00:35:28,545 --> 00:35:30,672 simply do not apply. 553 00:35:30,797 --> 00:35:32,466 They vanish. 554 00:35:33,550 --> 00:35:35,719 And life? 555 00:35:37,179 --> 00:35:38,847 Life? 556 00:35:41,558 --> 00:35:43,477 Life forever. 557 00:36:08,252 --> 00:36:10,712 If you were watching an astronaut... 558 00:36:10,838 --> 00:36:14,007 foolhardy enough to jump into a black hole... 559 00:36:14,132 --> 00:36:16,677 at some time on his watch... 560 00:36:16,802 --> 00:36:18,846 say, 12:00... 561 00:36:18,971 --> 00:36:21,598 he would cross the event horizon... 562 00:36:21,723 --> 00:36:23,976 and enter the black hole. 563 00:36:25,727 --> 00:36:28,605 But no matter how long you waited... 564 00:36:28,730 --> 00:36:33,443 you would never see the astronaut's watch reach 12:00. 565 00:36:34,778 --> 00:36:37,114 Instead, each second on the watch... 566 00:36:37,281 --> 00:36:40,033 would appear to take longer and longer... 567 00:36:40,159 --> 00:36:42,828 until the last second before midnight... 568 00:36:42,953 --> 00:36:45,080 would take forever. 569 00:36:46,665 --> 00:36:49,626 Thus, by jumping into a black hole... 570 00:36:49,793 --> 00:36:53,463 one could ensure that one's image lasted forever. 571 00:36:55,132 --> 00:36:57,885 But the picture would fade very rapidly... 572 00:36:58,010 --> 00:37:01,972 and grow so dim that no one could see it. 573 00:37:05,893 --> 00:37:08,437 As somebody disappears into a black hole... 574 00:37:08,562 --> 00:37:11,481 as seen from the outside, it looks as though... 575 00:37:11,648 --> 00:37:15,652 time actually slows down, and the person who's moving... 576 00:37:15,819 --> 00:37:18,155 at least he's thinking he's moving... 577 00:37:18,280 --> 00:37:21,116 he's perhaps talking in his spaceship at a normal rate... 578 00:37:21,241 --> 00:37:24,161 seems to slow down and ends up being frozen... 579 00:37:24,328 --> 00:37:26,997 in a particular position... 580 00:37:27,122 --> 00:37:29,875 as seen by somebody watching him from the outside. 581 00:37:30,000 --> 00:37:33,295 And as seen from the outside, you never see what happens after that. 582 00:37:40,010 --> 00:37:43,222 The astronaut wouldn't notice anything special... 583 00:37:43,347 --> 00:37:46,433 when his watch reached midnight... 584 00:37:46,558 --> 00:37:49,102 and he crossed the event horizon... 585 00:37:49,228 --> 00:37:51,271 into the black hole... 586 00:37:53,023 --> 00:37:57,194 until, of course, he approached the singularity... 587 00:37:57,319 --> 00:37:59,696 and was crushed into spaghetti. 588 00:38:06,787 --> 00:38:09,122 One can fall through this event horizon... 589 00:38:09,248 --> 00:38:12,042 without feeling anything, without noticing it. 590 00:38:12,167 --> 00:38:15,587 After about a week of falling, one begins to feel the pinch... 591 00:38:15,712 --> 00:38:18,382 and one extends longer and longer... 592 00:38:18,507 --> 00:38:20,676 and gets slightly thinner. 593 00:38:20,801 --> 00:38:24,429 And, of course, one begins to get squeezed... 594 00:38:24,555 --> 00:38:27,558 until one gets very long and very thin... 595 00:38:27,724 --> 00:38:29,893 and rather nasty. 596 00:38:30,018 --> 00:38:34,314 By the end of two weeks, one's fallen right into the center and is, of course, dead. 597 00:38:35,065 --> 00:38:37,901 Before you lose sight of the outer world... 598 00:38:38,026 --> 00:38:41,196 you would see things happening and see them at a greater rate... 599 00:38:41,321 --> 00:38:43,907 so that it would look like a firework display. 600 00:38:44,324 --> 00:38:47,411 The frustration would be that, although you would be able to see... 601 00:38:47,536 --> 00:38:50,581 everything that happens in the future, it would be going so fast... 602 00:38:50,747 --> 00:38:54,251 that from a scientific point of view, you'd have no time to analyze it. 603 00:38:54,376 --> 00:38:56,420 You wouldn't be able to take it in. 604 00:38:56,545 --> 00:38:58,714 Eventually things would be going off so fast... 605 00:38:58,839 --> 00:39:01,633 and it would be so explosive that you yourself would be... 606 00:39:01,758 --> 00:39:05,220 destroyed by the explosion, and that would be the end. 607 00:39:05,345 --> 00:39:09,099 But it would be a very exciting way to end one's life. 608 00:39:09,266 --> 00:39:12,644 It would be the way I would choose if I had the choice. 609 00:39:15,939 --> 00:39:18,734 In the long history of the universe... 610 00:39:18,859 --> 00:39:22,529 many stars must have burned up their nuclear fuel... 611 00:39:22,654 --> 00:39:25,115 and collapsed in on themselves. 612 00:39:27,242 --> 00:39:30,162 The number of black holes may be greater... 613 00:39:30,287 --> 00:39:32,664 than the number of visible stars... 614 00:39:32,789 --> 00:39:35,375 which totals about a hundred thousand million... 615 00:39:35,501 --> 00:39:37,461 in our galaxy alone. 616 00:39:39,963 --> 00:39:42,132 We also have evidence... 617 00:39:42,257 --> 00:39:45,219 that there is a very large black hole... 618 00:39:45,344 --> 00:39:48,305 at the center of our own galaxy. 619 00:39:54,937 --> 00:39:58,232 Friends ask me, "Well, if a black hole is black... 620 00:39:58,357 --> 00:40:00,359 how can you see it?" 621 00:40:00,484 --> 00:40:04,112 And I say, "Have you ever been to a ball? 622 00:40:04,238 --> 00:40:06,573 Have you ever watched the young men... 623 00:40:06,698 --> 00:40:10,202 dressed in their black evening tuxedos... 624 00:40:10,327 --> 00:40:12,496 and the girls in their white dresses... 625 00:40:12,621 --> 00:40:15,666 whirling around, held in each other's arms... 626 00:40:15,791 --> 00:40:17,793 and the lights turned low... 627 00:40:17,918 --> 00:40:20,504 and all you can see is the girls? 628 00:40:20,629 --> 00:40:23,549 Well, the girl is the ordinary star... 629 00:40:23,674 --> 00:40:26,593 and the boy is the black hole. 630 00:40:26,718 --> 00:40:30,806 You can't see the black hole any more than you can see the boy... 631 00:40:30,931 --> 00:40:34,643 but the girl going around gives you convincing evidence... 632 00:40:34,768 --> 00:40:38,689 there must be something there holding her in orbit." 633 00:40:40,983 --> 00:40:45,696 One evening, shortly after the birth of my daughter, Lucy... 634 00:40:45,863 --> 00:40:48,657 I started to think about black holes... 635 00:40:48,782 --> 00:40:50,868 as I was getting into bed. 636 00:40:53,453 --> 00:40:57,332 My disability makes this rather a slow process... 637 00:40:57,457 --> 00:41:00,669 so I had plenty of time. 638 00:41:00,794 --> 00:41:03,672 Suddenly I realized... 639 00:41:03,797 --> 00:41:06,300 that the area of the event horizon... 640 00:41:06,425 --> 00:41:09,094 must always increase with time. 641 00:41:11,430 --> 00:41:14,933 The increase in the area of the event horizon... 642 00:41:15,058 --> 00:41:18,228 was very reminiscent of a quantity called entropy... 643 00:41:18,395 --> 00:41:22,107 which measures the degree of disorder of a system. 644 00:41:23,317 --> 00:41:25,944 It is a matter of common experience... 645 00:41:26,069 --> 00:41:29,323 that disorder tends to increase with time... 646 00:41:29,448 --> 00:41:32,117 if things are left to themselves. 647 00:41:35,871 --> 00:41:40,292 Jacob Bekenstein came into the office one day. 648 00:41:40,417 --> 00:41:42,544 "Jacob," I said... 649 00:41:42,669 --> 00:41:44,713 "It always troubles me... 650 00:41:44,838 --> 00:41:48,050 when I put a hot teacup next to a cold teacup. 651 00:41:48,175 --> 00:41:51,678 I've increased, by letting heat flow from one to the other... 652 00:41:51,803 --> 00:41:54,056 the amount of disorder in the universe. 653 00:41:54,181 --> 00:41:57,726 But Jacob, if a black hole swims by... 654 00:41:57,851 --> 00:42:01,230 and I drop both teacups into this... 655 00:42:01,355 --> 00:42:04,900 I've concealed the evidence of my crime, have I not?" 656 00:42:06,902 --> 00:42:10,072 Bekenstein's a man of great integrity... 657 00:42:10,197 --> 00:42:13,492 and he looked troubled, and he came back to me later... 658 00:42:13,617 --> 00:42:15,911 and he said, "No, you have not... 659 00:42:16,036 --> 00:42:18,747 concealed the evidence of your crime. 660 00:42:18,872 --> 00:42:22,417 The black hole records what's happened to you." 661 00:42:22,543 --> 00:42:26,338 Stephen Hawking read the paper... 662 00:42:26,463 --> 00:42:29,967 in which Bekenstein announced this result... 663 00:42:30,092 --> 00:42:32,094 thought it was preposterous... 664 00:42:32,219 --> 00:42:34,805 and decided to prove it was wrong. 665 00:42:38,809 --> 00:42:42,646 My discoveries led Jacob Bekenstein to suggest... 666 00:42:42,813 --> 00:42:44,940 that the area of the event horizon... 667 00:42:45,065 --> 00:42:49,319 actually was the entropy of a black hole. 668 00:42:50,612 --> 00:42:52,823 But there was one fatal flaw... 669 00:42:52,948 --> 00:42:55,159 in Bekenstein's idea: 670 00:42:56,577 --> 00:42:58,996 If black holes have an entropy... 671 00:42:59,163 --> 00:43:01,665 they ought to have a temperature. 672 00:43:04,001 --> 00:43:06,086 And if they have a temperature... 673 00:43:06,211 --> 00:43:08,797 they ought to give off radiation. 674 00:43:10,883 --> 00:43:13,343 But how could they give off radiation... 675 00:43:13,468 --> 00:43:16,722 if nothing can escape from a black hole? 676 00:43:20,726 --> 00:43:22,477 As it turned out... 677 00:43:22,603 --> 00:43:25,189 Bekenstein was basically correct... 678 00:43:25,314 --> 00:43:28,192 though in a manner far more surprising... 679 00:43:28,358 --> 00:43:32,154 than he or anyone else had expected. 680 00:43:36,283 --> 00:43:39,286 As he gradually lost the use of his hands... 681 00:43:39,411 --> 00:43:44,041 he had to start developing... 682 00:43:44,208 --> 00:43:47,044 carefully choosing research projects... 683 00:43:47,169 --> 00:43:50,380 that could be tackled and solved... 684 00:43:50,547 --> 00:43:54,801 through geometrical arguments that he could do pictorially in his head. 685 00:43:54,927 --> 00:43:59,348 And he developed a very powerful set of tools nobody else really had. 686 00:43:59,640 --> 00:44:03,268 So in some sense, when you lose one set of tools... 687 00:44:03,393 --> 00:44:05,771 you may develop other tools, but the new tools... 688 00:44:05,896 --> 00:44:08,774 are amenable to different kinds of problems than the old tools. 689 00:44:08,899 --> 00:44:12,194 And if you're the only master in the world of these new tools... 690 00:44:12,319 --> 00:44:15,739 that means certain kinds of problems you can solve and nobody else can. 691 00:44:17,574 --> 00:44:20,577 My work up to 1973... 692 00:44:20,744 --> 00:44:22,996 was in general relativity... 693 00:44:23,121 --> 00:44:27,334 and was summarized in a book I wrote with George Ellis called... 694 00:44:27,459 --> 00:44:30,379 The Large Scale Structure of Space-Time. 695 00:44:33,006 --> 00:44:37,219 Even then, it was difficult for me to write things down... 696 00:44:38,971 --> 00:44:42,516 so I tended to think in pictures and diagrams... 697 00:44:42,641 --> 00:44:45,102 that I could visualize in my head. 698 00:45:20,053 --> 00:45:22,514 I remember visiting Stephen and Jane... 699 00:45:22,639 --> 00:45:24,850 at their home in Cambridge. 700 00:45:24,975 --> 00:45:27,936 After supper in the evening... 701 00:45:28,061 --> 00:45:31,231 when it was time for Stephen to go to bed... 702 00:45:31,356 --> 00:45:35,068 Jane insisted and Stephen acquiesced... I guess this was standard... 703 00:45:35,194 --> 00:45:37,154 that Stephen make his way up... 704 00:45:37,321 --> 00:45:40,574 I've forgotten whether it was one flight of stairs or two... alone... 705 00:45:40,699 --> 00:45:43,494 and this was a period when he could no longer walk. 706 00:45:43,660 --> 00:45:47,289 The way he got up the stairs was, he grabbed hold of the pillars... 707 00:45:47,414 --> 00:45:50,501 that support the banister and pulled him up with the strength... 708 00:45:50,626 --> 00:45:53,629 pulled himself up the stairs with the strength of his own arms... 709 00:45:53,754 --> 00:45:55,672 dragging himself up... 710 00:45:55,797 --> 00:45:58,509 from the ground floor up to the second story... 711 00:45:58,675 --> 00:46:02,346 in a long, arduous effort. 712 00:46:02,471 --> 00:46:05,265 Jane explained that... 713 00:46:05,390 --> 00:46:08,060 this was an important part of his physical therapy... 714 00:46:08,185 --> 00:46:12,272 to maintain his coordination... 715 00:46:12,397 --> 00:46:15,818 and strength as long as possible. 716 00:46:15,943 --> 00:46:18,445 At first it was sort of heartrending... 717 00:46:18,570 --> 00:46:22,199 to watch what appeared to be the agony of pulling himself up the stairs... 718 00:46:22,324 --> 00:46:26,036 until I understood it's just part of life... 719 00:46:26,203 --> 00:46:28,622 pulling himself up the stairs like that. 720 00:46:32,793 --> 00:46:35,712 General relativity is what is called... 721 00:46:35,838 --> 00:46:37,756 a classical theory. 722 00:46:39,550 --> 00:46:42,052 It predicts a single definite path... 723 00:46:42,219 --> 00:46:44,137 for each particle. 724 00:46:45,806 --> 00:46:48,308 But according to quantum mechanics... 725 00:46:48,433 --> 00:46:51,728 there is an element of chance or uncertainty. 726 00:46:53,814 --> 00:46:56,900 A particle does not have... 727 00:46:57,025 --> 00:47:01,405 just a single path through space and time. 728 00:47:02,281 --> 00:47:05,742 Instead, there is an uncertainty principle... 729 00:47:05,909 --> 00:47:09,079 according to which both the exact position... 730 00:47:09,204 --> 00:47:13,041 and velocity of a particle can never be known. 731 00:47:19,506 --> 00:47:22,134 I began investigating... 732 00:47:22,259 --> 00:47:25,262 the effect quantum mechanics might have... 733 00:47:25,387 --> 00:47:28,724 on particles near a black hole. 734 00:47:28,849 --> 00:47:31,727 I found that particles could escape... 735 00:47:31,852 --> 00:47:33,896 from a black hole... 736 00:47:34,021 --> 00:47:38,066 that black holes are not completely black. 737 00:47:38,192 --> 00:47:41,403 At first I didn't believe it. 738 00:47:42,613 --> 00:47:45,657 But when I redid the calculations... 739 00:47:45,782 --> 00:47:49,745 I couldn't get the effect to go away. 740 00:47:49,870 --> 00:47:53,707 I met Martin Rees, and he was shaking with excitement... 741 00:47:53,832 --> 00:47:56,168 and he said, "Have you heard? Have you heard... 742 00:47:56,293 --> 00:47:58,003 what Stephen has discovered? 743 00:47:58,128 --> 00:47:59,963 Everything is different! Everything is changed!" 744 00:48:00,088 --> 00:48:03,634 I was still unsure of my discovery... 745 00:48:03,759 --> 00:48:06,970 so I only told a few colleagues... 746 00:48:07,095 --> 00:48:10,724 but word soon spread. 747 00:48:10,849 --> 00:48:14,269 Roger Penrose phoned up on my birthday. 748 00:48:15,521 --> 00:48:18,982 He was very excited and went on so long... 749 00:48:19,149 --> 00:48:22,486 that my birthday dinner got quite cold. 750 00:48:24,154 --> 00:48:27,616 It was a great pity, because it was goose... 751 00:48:27,741 --> 00:48:30,911 which I'm very fond of. 752 00:48:31,036 --> 00:48:34,790 To me it's a miracle, 'cause it's a complicated and messy calculation. 753 00:48:34,915 --> 00:48:37,835 We can now do these things very much better... 754 00:48:37,960 --> 00:48:40,212 and it's more transparent what happens. 755 00:48:40,337 --> 00:48:43,507 But out of this messy calculation, he showed that black holes... 756 00:48:43,632 --> 00:48:45,926 aren't black with this quantum mechanical effect. 757 00:48:46,051 --> 00:48:48,178 There was a residual radiation. 758 00:48:48,345 --> 00:48:50,347 Stephen came to a meeting... 759 00:48:50,472 --> 00:48:52,057 and people were flabbergasted. 760 00:48:52,182 --> 00:48:54,685 I remember someone saying, "You must be wrong, Stephen. 761 00:48:54,852 --> 00:48:56,687 I don't believe a word of it." 762 00:48:57,020 --> 00:48:59,606 I once said that I was unhappy... 763 00:48:59,731 --> 00:49:03,861 with the explanation given in terms of negative energy particles being created. 764 00:49:04,153 --> 00:49:07,030 But I feel this is part of the controversy of science. 765 00:49:07,197 --> 00:49:11,201 You must have the give and take, and I'm delighted to be a part of that. 766 00:49:11,368 --> 00:49:13,370 That's what makes it fun. 767 00:49:13,495 --> 00:49:16,206 If you all sat down and said, "Oh, lovely"... 768 00:49:16,331 --> 00:49:18,709 when you do have niggling questions in your mind... 769 00:49:18,876 --> 00:49:21,003 that's not doing a service to science. 770 00:49:21,128 --> 00:49:24,047 But I was not antagonistic to it in any way... 771 00:49:24,214 --> 00:49:27,384 except for that one time when I questioned. 772 00:49:29,052 --> 00:49:31,138 I finally convinced myself... 773 00:49:31,263 --> 00:49:33,223 that black holes radiate... 774 00:49:33,348 --> 00:49:37,019 when I found a mechanism through which this could happen. 775 00:49:38,395 --> 00:49:41,398 According to quantum mechanics... 776 00:49:41,523 --> 00:49:44,443 space is filled with virtual particles... 777 00:49:44,568 --> 00:49:46,445 and antiparticles... 778 00:49:46,570 --> 00:49:49,698 that are constantly materializing in pairs... 779 00:49:49,823 --> 00:49:52,910 separating, coming together again... 780 00:49:53,076 --> 00:49:55,329 and annihilating each other. 781 00:49:58,499 --> 00:50:01,084 In the presence of a black hole... 782 00:50:01,251 --> 00:50:04,046 one member of a pair of virtual particles... 783 00:50:04,171 --> 00:50:06,131 may fall into the hole... 784 00:50:06,256 --> 00:50:08,842 leaving the other member without a partner... 785 00:50:08,967 --> 00:50:11,136 with which to annihilate. 786 00:50:12,679 --> 00:50:16,517 The forsaken particle appears to be radiation... 787 00:50:16,642 --> 00:50:18,852 emitted by the black hole. 788 00:50:23,106 --> 00:50:26,985 And so black holes are not eternal. 789 00:50:29,571 --> 00:50:32,950 They evaporate away at an increasing rate... 790 00:50:33,075 --> 00:50:37,079 until they vanish in a gigantic explosion. 791 00:50:40,207 --> 00:50:44,545 Quantum mechanics has allowed particles and radiation... 792 00:50:44,670 --> 00:50:47,714 to escape from the ultimate prison... 793 00:50:47,840 --> 00:50:50,217 a black hole. 794 00:50:52,302 --> 00:50:55,597 Einstein never accepted quantum mechanics... 795 00:50:55,722 --> 00:50:59,101 because of its element of chance and uncertainty. 796 00:51:00,644 --> 00:51:04,439 He said, "God does not play dice." 797 00:51:05,774 --> 00:51:09,486 It seems that Einstein was doubly wrong. 798 00:51:12,197 --> 00:51:14,867 The quantum effects of black holes... 799 00:51:14,992 --> 00:51:18,537 suggest that not only does God play dice... 800 00:51:18,662 --> 00:51:20,664 he sometimes throws them... 801 00:51:20,831 --> 00:51:23,000 where they cannot be seen. 802 00:51:24,626 --> 00:51:26,879 He says himself... 803 00:51:27,004 --> 00:51:28,922 that, uh... 804 00:51:29,047 --> 00:51:32,593 he wouldn't have got to where he is if he hadn't been ill. 805 00:51:32,718 --> 00:51:34,595 And I think that's quite possible... 806 00:51:34,720 --> 00:51:37,055 because it's like Johnson said: 807 00:51:37,181 --> 00:51:39,766 The knowledge you're to be hanged in the morning... 808 00:51:39,892 --> 00:51:41,768 concentrates the mind wonderfully. 809 00:51:41,894 --> 00:51:44,188 And he has concentrated on this in a way... 810 00:51:44,354 --> 00:51:47,357 I don't think he would have, because he took a great interest... 811 00:51:47,524 --> 00:51:49,359 in a lot of things in life... 812 00:51:49,485 --> 00:51:52,529 and I don't know that he'd have applied himself the same way... 813 00:51:52,654 --> 00:51:56,909 if he'd been able to get around as he used to do, so in a way... 814 00:51:57,034 --> 00:52:00,704 No, I can't think anyone's lucky having an illness like that, even so. 815 00:52:00,829 --> 00:52:05,375 But it's less bad luck for him than it would be for some people... 816 00:52:05,501 --> 00:52:08,545 because he can so much live in his head. 817 00:52:08,962 --> 00:52:11,965 When I lived with the Hawking family, I would usually get up... 818 00:52:12,090 --> 00:52:14,885 around 7:15 or 7:30 and take a shower... 819 00:52:15,010 --> 00:52:18,013 and then read in my Bible some in the morning and pray... 820 00:52:18,138 --> 00:52:20,933 and then go down at 8:15 to get Stephen up. 821 00:52:21,058 --> 00:52:25,062 And at breakfast I would often tell him what I'd been reading in the Bible... 822 00:52:25,229 --> 00:52:28,774 hoping that this would eventually have some influence. 823 00:52:28,899 --> 00:52:31,443 So then we would go into work... 824 00:52:31,568 --> 00:52:35,155 and usually we'd go in and see if there were any scientific papers... 825 00:52:35,280 --> 00:52:37,282 that people sent out. 826 00:52:37,407 --> 00:52:41,787 I did discover that despite Hawking's great brilliance, he does read quite slowly. 827 00:52:41,912 --> 00:52:44,706 I could read about twice as fast as he. 828 00:52:44,832 --> 00:52:48,085 But of course he would have to read to remember it... 829 00:52:48,252 --> 00:52:52,047 because it would be very difficult for him to go back and access the thing... 830 00:52:52,172 --> 00:52:54,925 whereas I could skim the paper rather quickly and see... 831 00:52:55,050 --> 00:52:56,760 "Is there something interesting in this?" 832 00:52:56,885 --> 00:53:01,098 If I wanted to work on it, I could pick the thing up and look at it. 833 00:53:02,182 --> 00:53:04,476 Black hole radiation... 834 00:53:04,601 --> 00:53:07,771 has shown us that gravitational collapse... 835 00:53:07,938 --> 00:53:10,774 is not as final as we once thought. 836 00:53:12,693 --> 00:53:15,988 If an astronaut falls into a black hole... 837 00:53:16,113 --> 00:53:19,491 he will be returned to the rest of the universe... 838 00:53:19,616 --> 00:53:22,452 in the form of radiation. 839 00:53:23,620 --> 00:53:25,455 Thus, in a sense... 840 00:53:25,581 --> 00:53:28,041 the astronaut will be recycled. 841 00:53:30,335 --> 00:53:34,381 However, it would be a poor sort of immortality... 842 00:53:34,506 --> 00:53:37,551 because any personal concept of time... 843 00:53:37,676 --> 00:53:41,013 would come to an end as he is torn apart... 844 00:53:41,138 --> 00:53:43,098 inside the black hole. 845 00:53:46,351 --> 00:53:48,228 All that would survive... 846 00:53:48,353 --> 00:53:51,148 would be his mass, or energy. 847 00:53:56,820 --> 00:53:59,156 One year, the Hawkings took me along... 848 00:53:59,281 --> 00:54:02,117 when we went to a cottage in Wales... 849 00:54:02,242 --> 00:54:03,785 near the River Wye... 850 00:54:03,911 --> 00:54:06,330 and this cottage was up a hill... 851 00:54:06,455 --> 00:54:09,750 and there was a bit of... 852 00:54:09,875 --> 00:54:13,337 a paved little sidewalk that went up to the cottage... 853 00:54:13,504 --> 00:54:16,048 which I had not been up, and of course... 854 00:54:16,173 --> 00:54:19,843 I wanted to do it in the least number of trips I could imagine... 855 00:54:19,968 --> 00:54:22,137 so we put Stephen's batteries under his chair... 856 00:54:22,262 --> 00:54:25,349 his wheelchair has space for batteries... and put extra batteries under there... 857 00:54:25,516 --> 00:54:27,809 which Stephen didn't realize that I'd put under there... 858 00:54:27,935 --> 00:54:30,437 so he didn't realize his wheelchair was as heavily laden. 859 00:54:30,854 --> 00:54:34,650 Stephen got quite a bit ahead of me, and he was turning the corner... 860 00:54:34,775 --> 00:54:37,861 to go around to his house, but that was on a slope... 861 00:54:38,028 --> 00:54:41,782 so I looked up, and I noticed Stephen's wheelchair slowly tipping backward. 862 00:54:41,907 --> 00:54:45,702 Of course, I was about ten meters away... 863 00:54:45,869 --> 00:54:49,373 and tried to run up there, but I was not able to get there... 864 00:54:49,498 --> 00:54:53,043 rapidly enough before he toppled backward into the bushes. 865 00:54:53,168 --> 00:54:55,963 So it was a bit of a shocking sight... 866 00:54:56,088 --> 00:54:58,382 to see this master of gravity getting overcome... 867 00:54:58,507 --> 00:55:01,385 by the weak gravitational force of Earth. 868 00:55:02,302 --> 00:55:06,640 One of the worst things for me would be having people there all the time. 869 00:55:06,765 --> 00:55:09,017 Never alone. I couldn't bear that. 870 00:55:09,142 --> 00:55:12,396 And yet he finds things funny... 871 00:55:12,521 --> 00:55:16,275 and he enjoys life and he goes dashing about all over the place... 872 00:55:16,400 --> 00:55:18,235 and I think this is tremendous. 873 00:55:18,402 --> 00:55:20,779 But it's a sort of courage I haven't got... 874 00:55:20,904 --> 00:55:24,658 and his father hadn't got it, and we cannot but admire it... 875 00:55:24,783 --> 00:55:27,995 but wonder how on earth he got it, really. 876 00:55:28,328 --> 00:55:30,455 There must have been 50 people there... 877 00:55:30,581 --> 00:55:33,333 and I was standing off in a corner... 878 00:55:33,458 --> 00:55:36,628 sort of watching quietly... 879 00:55:36,753 --> 00:55:38,755 for a few minutes, relaxing... 880 00:55:38,922 --> 00:55:41,633 and Stephen was over there, not far from me. 881 00:55:41,758 --> 00:55:44,052 Jane walked over to Stephen and looked at him. 882 00:55:44,178 --> 00:55:46,680 He was sitting there with his head in his lap... 883 00:55:46,805 --> 00:55:49,433 like only Stephen can put his head in his lap. 884 00:55:49,558 --> 00:55:52,019 And Jane said to Stephen... 885 00:55:52,144 --> 00:55:55,272 "You look miserable, Stephen. Sit up straight. 886 00:55:55,439 --> 00:55:57,232 Some of your guests don't understand... 887 00:55:57,357 --> 00:55:59,902 that you're thinking about physics and having a wonderful time. 888 00:56:00,027 --> 00:56:03,530 It looks like you're in pain. Sit up and go talk to your guests." 889 00:56:05,782 --> 00:56:07,784 In 1979... 890 00:56:07,951 --> 00:56:12,039 I was elected Lucasian Professor of Mathematics. 891 00:56:13,916 --> 00:56:18,712 This is the same chair once held by Isaac Newton. 892 00:56:20,422 --> 00:56:24,718 They have a big book which every university teaching officer... 893 00:56:24,843 --> 00:56:26,929 is supposed to sign. 894 00:56:28,430 --> 00:56:32,059 After I had been Lucasian Professor for about a year... 895 00:56:32,184 --> 00:56:34,770 they realized I had never signed. 896 00:56:36,855 --> 00:56:39,483 So they brought the book to my office... 897 00:56:39,608 --> 00:56:42,444 and I signed with some difficulty. 898 00:56:44,196 --> 00:56:47,825 That was the last time I signed my name. 899 00:56:59,294 --> 00:57:02,881 My interest in the origin and fate of the universe... 900 00:57:03,006 --> 00:57:05,217 was reawakened when I attended... 901 00:57:05,342 --> 00:57:08,804 a conference on cosmology in the Vatican. 902 00:57:10,931 --> 00:57:13,183 Afterwards, we were granted... 903 00:57:13,308 --> 00:57:16,228 an audience with the pope. 904 00:57:16,353 --> 00:57:18,939 He told us that it was all right... 905 00:57:19,064 --> 00:57:21,650 to study the evolution of the universe... 906 00:57:21,775 --> 00:57:24,319 after the Big Bang... 907 00:57:24,444 --> 00:57:28,031 but we should not inquire into the Big Bang itself... 908 00:57:28,198 --> 00:57:31,118 because that was the moment of creation... 909 00:57:31,243 --> 00:57:33,996 and therefore the work of God. 910 00:57:36,331 --> 00:57:39,209 I was glad that he did not know... 911 00:57:39,376 --> 00:57:42,796 the subject of the talk I had just given... 912 00:57:44,590 --> 00:57:48,635 the possibility that the universe had no beginning... 913 00:57:48,760 --> 00:57:51,054 no moment of creation. 914 00:57:56,560 --> 00:58:00,355 There were theories in the early '70s... the first type of creation theories... 915 00:58:00,481 --> 00:58:04,318 where the people concerned started off with a fixed, external space and time... 916 00:58:04,443 --> 00:58:06,570 which for eternity was empty... 917 00:58:06,737 --> 00:58:09,740 and then suddenly, for some unknown reason, the universe nucleates... 918 00:58:09,865 --> 00:58:12,743 at a particular point and then, bang, it blows apart. 919 00:58:12,868 --> 00:58:16,538 But the trouble is that when space and time appear in the classical theory... 920 00:58:16,663 --> 00:58:20,083 that actual point itself is a singular point in the mathematics. 921 00:58:20,209 --> 00:58:22,169 Mathematics breaks down, and so... 922 00:58:22,294 --> 00:58:25,088 you cannot use that to give you a creation theory. 923 00:58:27,007 --> 00:58:29,092 If one goes back in time... 924 00:58:29,218 --> 00:58:32,596 one comes to the Big Bang singularity... 925 00:58:32,721 --> 00:58:35,599 where the laws of physics break down. 926 00:58:37,392 --> 00:58:40,145 But there's another direction of time... 927 00:58:40,270 --> 00:58:44,650 that one can go in which avoids the singularity. 928 00:58:46,485 --> 00:58:50,781 This is called the imaginary direction of time. 929 00:58:52,324 --> 00:58:54,451 In imaginary time... 930 00:58:54,618 --> 00:58:57,538 there need not be any singularities... 931 00:58:57,663 --> 00:59:01,500 which form a beginning or end to time. 932 00:59:04,878 --> 00:59:08,006 When you come to imaginary time, you have this rather peculiar possibility... 933 00:59:08,131 --> 00:59:10,300 of having a "now," as it were... 934 00:59:10,467 --> 00:59:12,636 without necessarily having a sort of a chain... 935 00:59:12,761 --> 00:59:15,973 of past moments. 936 00:59:16,139 --> 00:59:19,935 If we start where we are at the moment and start running backwards in time... 937 00:59:20,060 --> 00:59:22,521 then for a long time, things work perfectly normally. 938 00:59:22,646 --> 00:59:25,524 But as you begin to get further and further back towards... 939 00:59:25,649 --> 00:59:28,819 what would be the origin point in the conventional real-time picture... 940 00:59:28,986 --> 00:59:31,905 you'd find that the nature of time changes... 941 00:59:32,030 --> 00:59:35,617 that the imaginary component becomes more and more prominent... 942 00:59:35,742 --> 00:59:39,121 until what ought to have been the singular point in the classical theory... 943 00:59:39,246 --> 00:59:41,582 gets smoothed away, and you have this beautiful picture... 944 00:59:41,707 --> 00:59:44,501 of these bowls where the creation of the universe is pictures... 945 00:59:44,626 --> 00:59:47,504 of where we are now, and a smooth bowl of the past... 946 00:59:47,629 --> 00:59:50,757 where there's no initial point, just a sort of smooth shape. 947 00:59:59,266 --> 01:00:02,478 So long as the universe had a beginning... 948 01:00:02,603 --> 01:00:05,689 we could suppose it had a creator. 949 01:00:07,316 --> 01:00:11,153 But if the universe is completely self-contained... 950 01:00:11,278 --> 01:00:13,822 having no boundary or edge... 951 01:00:15,199 --> 01:00:18,827 it would neither be created nor destroyed. 952 01:00:18,952 --> 01:00:21,705 It would simply be. 953 01:00:24,374 --> 01:00:27,544 What place, then, for a creator? 954 01:00:31,882 --> 01:00:34,384 All you can really say is that the universe is... 955 01:00:34,551 --> 01:00:36,512 because it's a self-consistent mathematical structure. 956 01:00:36,637 --> 01:00:39,681 There's no past because, unlike the creation-as-a-point scenario... 957 01:00:39,806 --> 01:00:41,850 there's nothing for it to be created in. 958 01:00:41,975 --> 01:00:45,354 So to say it's created from nothing is a bit of a misnomer. 959 01:00:45,479 --> 01:00:47,481 It's a misleading use of the word "nothing". 960 01:00:47,606 --> 01:00:52,152 It's not just that there was empty space in which the universe appeared, which you might call "nothing". 961 01:00:52,277 --> 01:00:55,572 There was really nothing at all, because there wasn't even a creation event. 962 01:00:55,739 --> 01:00:59,493 The use of a past tense in a verb becomes inappropriate in these theories. 963 01:00:59,618 --> 01:01:02,913 Unfortunately, tenses were set up when people believed in real time, of course... 964 01:01:03,038 --> 01:01:06,917 and we don't yet have a linguistic form to describe tenses in imaginary time. 965 01:01:07,334 --> 01:01:11,547 The word "time" was not handed down from heaven... 966 01:01:11,672 --> 01:01:13,799 as a gift from on high. 967 01:01:13,924 --> 01:01:16,969 The idea of time is a word... 968 01:01:17,094 --> 01:01:19,263 invented by man... 969 01:01:19,429 --> 01:01:22,057 and if it has puzzlements connected with it... 970 01:01:22,182 --> 01:01:24,768 whose fault is it? It's our fault. 971 01:01:27,980 --> 01:01:29,982 Where does the difference... 972 01:01:30,107 --> 01:01:32,776 between the past and the future come from? 973 01:01:35,112 --> 01:01:38,073 The laws of science do not distinguish... 974 01:01:38,198 --> 01:01:40,534 between the past and the future. 975 01:01:41,994 --> 01:01:44,621 Yet there is a big difference... 976 01:01:44,788 --> 01:01:48,458 between the past and future in ordinary life. 977 01:01:54,923 --> 01:01:58,385 You may see a cup of tea fall off a table... 978 01:01:58,510 --> 01:02:01,638 and break into pieces on the floor... 979 01:02:01,763 --> 01:02:05,517 but you will never see the cup gather itself back together... 980 01:02:05,642 --> 01:02:08,020 and jump back on the table. 981 01:02:11,106 --> 01:02:14,109 The increase of disorder, or entropy... 982 01:02:14,234 --> 01:02:17,779 is what distinguishes the past from the future... 983 01:02:17,905 --> 01:02:20,407 giving a direction to time. 984 01:02:26,663 --> 01:02:28,999 He fell ill in Switzerland. 985 01:02:29,166 --> 01:02:32,294 When he came back, he was on a ventilator. 986 01:02:32,419 --> 01:02:35,547 Because he's on a ventilator, you've got a tube down your throat... 987 01:02:35,672 --> 01:02:38,008 and therefore you can't speak, just for that reason. 988 01:02:38,550 --> 01:02:41,386 For that period, which may have been a couple of months... 989 01:02:41,512 --> 01:02:46,183 I spent probably one in two nights, one in three nights, at the hospital... 990 01:02:46,308 --> 01:02:49,728 because when he was in hospital... 991 01:02:49,853 --> 01:02:52,022 he couldn't communicate with the nurses. 992 01:02:52,189 --> 01:02:54,525 It's not just like being seriously ill... 993 01:02:54,650 --> 01:02:58,278 but you're in a position where the nurses couldn't understand what Stephen wanted. 994 01:02:58,403 --> 01:03:01,365 If Stephen was uncomfortable, they couldn't tell why. 995 01:03:04,159 --> 01:03:06,411 Before I caught pneumonia... 996 01:03:06,537 --> 01:03:09,331 my speech had been getting more slurred... 997 01:03:09,456 --> 01:03:13,001 so that only a few people who knew me well... 998 01:03:13,126 --> 01:03:15,045 could understand me. 999 01:03:16,547 --> 01:03:19,049 But at least I could communicate. 1000 01:03:21,385 --> 01:03:23,387 I wrote scientific papers... 1001 01:03:23,512 --> 01:03:25,889 by dictating to a secretary... 1002 01:03:26,056 --> 01:03:28,892 and I gave seminars through an interpreter. 1003 01:03:30,060 --> 01:03:33,021 And then, a tracheostomy operation... 1004 01:03:33,147 --> 01:03:36,400 removed my ability to speak altogether. 1005 01:03:40,320 --> 01:03:43,615 After a long time... well, it seemed like a long time... 1006 01:03:43,740 --> 01:03:46,410 somebody came up with this brilliant gadget. 1007 01:03:46,535 --> 01:03:49,246 They didn't have it at the Cambridge hospital. 1008 01:03:49,413 --> 01:03:51,415 They got it from somewhere in London. 1009 01:03:51,540 --> 01:03:55,294 This was high technology... how you can communicate with a person with no voice. 1010 01:03:55,419 --> 01:03:59,173 It's a plastic piece of Perspex about so big... 1011 01:03:59,298 --> 01:04:03,760 and you've got the letters of the alphabet arranged like that, and a hole in the middle. 1012 01:04:03,927 --> 01:04:06,430 You hold it up between you and the other person. 1013 01:04:06,555 --> 01:04:10,476 They look at a letter, and you can see which letter they're looking at... 1014 01:04:10,601 --> 01:04:13,228 most of the time. Sometimes you can't be sure. 1015 01:04:13,353 --> 01:04:16,607 So you would get the patient to spell out what they wanted. 1016 01:04:16,773 --> 01:04:19,610 So each letter... they have to look to pick out the A. 1017 01:04:19,776 --> 01:04:22,779 You say, "A?" Did you get it right? It's like a guessing game. 1018 01:04:45,010 --> 01:04:49,389 Stephen wasn't willing to accept that he wasn't going to speak again... 1019 01:04:49,515 --> 01:04:51,683 and he thought he would be giving in... 1020 01:04:51,809 --> 01:04:55,646 by trying to find a method of communicating other than speech. 1021 01:04:56,063 --> 01:04:59,817 I remember I went in one evening... 1022 01:04:59,983 --> 01:05:02,653 and this was the first time that he asked... 1023 01:05:02,820 --> 01:05:05,364 to be gotten out of bed to use the computer. 1024 01:05:05,489 --> 01:05:09,117 Sometimes they'd sit him up so he wasn't lying in bed all the time... 1025 01:05:09,243 --> 01:05:12,496 as you do with a patient, but this time when I turned up... 1026 01:05:12,663 --> 01:05:15,457 he asked the nurse, could he be gotten out of bed... 1027 01:05:16,792 --> 01:05:19,086 so he could use the computer, and he did. 1028 01:05:19,211 --> 01:05:22,422 I remember the first thing he typed on there after saying hello... 1029 01:05:22,548 --> 01:05:25,425 Stephen's always very polite about things like that... 1030 01:05:25,551 --> 01:05:29,346 was, "Will you help me finish my book?" 1031 01:05:35,060 --> 01:05:37,771 A computer expert in California... 1032 01:05:37,896 --> 01:05:39,898 heard of my plight... 1033 01:05:40,023 --> 01:05:42,359 and sent me a computer program... 1034 01:05:42,526 --> 01:05:44,319 called Equalizer. 1035 01:05:46,405 --> 01:05:48,907 This allowed me to select words... 1036 01:05:49,032 --> 01:05:52,035 from a series of menus on a screen... 1037 01:05:52,161 --> 01:05:54,997 by pressing a switch in my hand. 1038 01:05:59,042 --> 01:06:03,297 These words could then be sent to a speech synthesizer... 1039 01:06:03,422 --> 01:06:05,799 attached to my wheelchair. 1040 01:06:08,093 --> 01:06:10,095 Much to my surprise... 1041 01:06:10,220 --> 01:06:12,890 I found I was able to communicate... 1042 01:06:13,056 --> 01:06:15,058 much better than before. 1043 01:06:18,562 --> 01:06:21,607 When eventually he went home from hospital... 1044 01:06:21,732 --> 01:06:24,651 he was told he needed 24-hour nursing, and everyone was saying... 1045 01:06:24,776 --> 01:06:27,362 "How is he going to go in and do work? 1046 01:06:27,488 --> 01:06:30,908 Is he going to trail around with nurses after him in the office?" 1047 01:06:31,074 --> 01:06:33,076 And of course he did. 1048 01:06:33,202 --> 01:06:36,705 They talked originally of him working at home... 1049 01:06:36,830 --> 01:06:39,082 which he wasn't happy with. 1050 01:06:40,792 --> 01:06:44,171 And so, after a period of recuperation at home... 1051 01:06:44,296 --> 01:06:46,757 he just decided to go back into the office. 1052 01:06:46,924 --> 01:06:50,135 And he'd make the trip from his house to the office... 1053 01:06:50,260 --> 01:06:53,055 which is, I don't know, half a mile in his wheelchair... 1054 01:06:53,180 --> 01:06:54,932 with a nurse walking along with him. 1055 01:06:55,098 --> 01:06:57,851 This is at the time when he was still driving around... 1056 01:06:57,976 --> 01:06:59,895 with the bag and the nasal drip... 1057 01:07:00,020 --> 01:07:03,941 going into the department, working, going back home. 1058 01:07:07,778 --> 01:07:10,280 I began to wonder what would happen... 1059 01:07:10,447 --> 01:07:13,200 when the universe stopped expanding... 1060 01:07:13,325 --> 01:07:15,702 and began to contract. 1061 01:07:17,204 --> 01:07:19,456 Would we see broken cups... 1062 01:07:19,581 --> 01:07:22,251 gather themselves together off the floor... 1063 01:07:22,376 --> 01:07:25,003 and jump back onto the table? 1064 01:07:27,297 --> 01:07:30,801 Would we be able to remember tomorrow's prices... 1065 01:07:30,968 --> 01:07:34,054 and make a fortune off the stock market? 1066 01:07:36,390 --> 01:07:38,267 It seemed to me... 1067 01:07:38,392 --> 01:07:41,562 the universe had to return to a smooth and ordered state... 1068 01:07:41,687 --> 01:07:43,647 when it recollapsed. 1069 01:07:46,483 --> 01:07:49,736 If this were so, time would go backwards... 1070 01:07:49,862 --> 01:07:52,656 when the universe began to collapse. 1071 01:07:54,992 --> 01:07:59,163 People in the contracting phase would live their lives backward. 1072 01:07:59,288 --> 01:08:01,832 They would die before they were born... 1073 01:08:01,957 --> 01:08:05,544 and get younger as the universe got small again. 1074 01:08:06,795 --> 01:08:10,174 Eventually, they would return to the womb. 1075 01:08:13,427 --> 01:08:15,929 He gave me my first problem to do. 1076 01:08:17,681 --> 01:08:20,267 He asked me to look at this mathematical problem. 1077 01:08:20,392 --> 01:08:23,270 Usually when he gives a problem, he has a good idea... 1078 01:08:23,395 --> 01:08:25,439 of what the answer should be. 1079 01:08:25,564 --> 01:08:29,109 I went to look at it, and it took me a few months... 1080 01:08:29,234 --> 01:08:33,280 to understand what it was about, and I came back and said, "I get this answer." 1081 01:08:33,405 --> 01:08:36,867 And he said to me, "No, that is not what I expected." 1082 01:08:37,034 --> 01:08:41,079 I said, "That's what I get." So I went to the blackboard, explained what it was. 1083 01:08:41,205 --> 01:08:45,000 He said, "Did you think about that particular case?" I said, "No, I didn't." 1084 01:08:45,125 --> 01:08:47,169 So I went back... 1085 01:08:47,294 --> 01:08:50,005 and I calculated what he'd talked to me about. 1086 01:08:50,130 --> 01:08:54,259 I came back a few weeks after, and I said, "Stephen, I don't get this thing. 1087 01:08:54,384 --> 01:08:57,513 I still get the same answer I had originally." 1088 01:08:57,638 --> 01:09:00,307 So he said to me, "No, no, no, no. 1089 01:09:00,432 --> 01:09:02,434 This doesn't work. Did you think about that?" 1090 01:09:02,559 --> 01:09:05,229 I said, "Oh, no. I'd forgotten about that particular case." 1091 01:09:05,354 --> 01:09:08,690 So I went back to the drawing board and started calculating again... 1092 01:09:08,816 --> 01:09:10,818 and again I got the same answer. 1093 01:09:10,943 --> 01:09:14,988 So I went back to see Stephen, and this dragged on for two or three months. 1094 01:09:16,573 --> 01:09:18,867 Finally he said to me... 1095 01:09:18,992 --> 01:09:21,245 "Maybe one of your approximations is not valid." 1096 01:09:23,038 --> 01:09:26,583 So me and a colleague decided to do the thing with computers. 1097 01:09:26,708 --> 01:09:29,837 This takes a lot of time to write the programs... 1098 01:09:29,962 --> 01:09:31,713 and to be sure the program was correct. 1099 01:09:31,839 --> 01:09:35,425 We get the answer, and it was still the way I'd said before... 1100 01:09:35,551 --> 01:09:39,763 and not the way Stephen said, so we went to see Stephen and said, "See? Again." 1101 01:09:43,767 --> 01:09:45,811 I had made a mistake. 1102 01:09:48,188 --> 01:09:52,109 I had been using too simple a model of the universe. 1103 01:09:54,444 --> 01:09:56,405 Time will not reverse direction... 1104 01:09:56,530 --> 01:09:59,449 when the universe begins to contract. 1105 01:10:02,953 --> 01:10:05,831 People will continue to get older... 1106 01:10:05,956 --> 01:10:10,127 so it is no good waiting until the universe recollapses... 1107 01:10:10,252 --> 01:10:12,296 to return to our youth. 1108 01:10:28,437 --> 01:10:31,231 Einstein once asked the question... 1109 01:10:31,356 --> 01:10:33,650 "How much choice did God have... 1110 01:10:33,817 --> 01:10:36,278 in constructing the universe?" 1111 01:10:38,489 --> 01:10:43,243 If my proposal that the universe has no boundary is correct... 1112 01:10:43,368 --> 01:10:45,496 he had no freedom at all... 1113 01:10:45,621 --> 01:10:48,207 to choose how the universe began. 1114 01:10:50,167 --> 01:10:52,586 He would only have had the freedom... 1115 01:10:52,711 --> 01:10:55,672 to choose the laws the universe obeyed. 1116 01:10:57,633 --> 01:10:59,885 This, however, may not have been... 1117 01:11:00,010 --> 01:11:02,262 all that much of a choice. 1118 01:11:04,097 --> 01:11:07,643 There may well be only one unified theory... 1119 01:11:07,768 --> 01:11:10,479 that allows for the existence of structures... 1120 01:11:10,604 --> 01:11:13,357 as complicated as human beings... 1121 01:11:13,524 --> 01:11:17,110 who can investigate the laws of the universe... 1122 01:11:17,236 --> 01:11:19,822 and ask about the nature of God. 1123 01:11:27,955 --> 01:11:30,999 I don't know how clear-cut these experiments are... 1124 01:11:31,124 --> 01:11:35,295 but there are experiments that have been done on the timing of consciousness... 1125 01:11:35,420 --> 01:11:38,382 and they seem to lead to a very odd picture... 1126 01:11:38,549 --> 01:11:41,343 which doesn't even quite make consistent sense. 1127 01:11:41,468 --> 01:11:43,554 Whether refinement of these experiments... 1128 01:11:43,720 --> 01:11:46,557 might get rid of this kind of anomaly I'm not sure... 1129 01:11:46,682 --> 01:11:50,561 but it does look a little as though there is something very odd about consciousness... 1130 01:11:50,727 --> 01:11:54,314 and somehow almost as though the future affects the past in some way... 1131 01:11:54,439 --> 01:11:57,943 over a very tiny, limited scale, but something maybe of the order... 1132 01:11:58,068 --> 01:12:00,028 of a reasonable fraction of a second. 1133 01:12:00,362 --> 01:12:02,406 And there's no reason to believe... 1134 01:12:02,531 --> 01:12:05,284 that one's conscious experience... 1135 01:12:05,409 --> 01:12:08,328 shouldn't be part of somebody else's... 1136 01:12:08,453 --> 01:12:10,247 at some other stage. 1137 01:12:10,414 --> 01:12:13,709 I don't know if it's fair to say what happens after one dies... 1138 01:12:13,834 --> 01:12:16,003 but it's a plausible picture... 1139 01:12:16,128 --> 01:12:17,921 that you could be somebody else... 1140 01:12:18,046 --> 01:12:22,050 and that somebody else could be somebody that lived in the past, not in the future. 1141 01:12:25,387 --> 01:12:29,516 Even if there is only one possible unified theory... 1142 01:12:29,641 --> 01:12:32,895 that is just a set of rules and equations... 1143 01:12:34,480 --> 01:12:37,858 what is it that breathes fire into the equations... 1144 01:12:37,983 --> 01:12:41,487 and makes a universe for them to describe? 1145 01:12:43,447 --> 01:12:47,743 Why does the universe go to all the bother of existing? 1146 01:12:49,953 --> 01:12:52,623 Is the unified theory so compelling... 1147 01:12:52,748 --> 01:12:55,792 that it brings about its own existence? 1148 01:12:57,127 --> 01:12:59,379 Or does it need a creator? 1149 01:13:00,672 --> 01:13:02,549 And, if so... 1150 01:13:02,674 --> 01:13:04,635 who created him? 1151 01:13:13,727 --> 01:13:17,022 I think I would say that the universe has a purpose. 1152 01:13:17,147 --> 01:13:20,317 It's not somehow just there by chance. 1153 01:13:20,442 --> 01:13:23,111 I think it's... Yeah. 1154 01:13:23,237 --> 01:13:25,697 So... 1155 01:13:25,823 --> 01:13:28,283 it's... it's... 1156 01:13:28,408 --> 01:13:31,662 Some people, I think, take the view that the universe is just there... 1157 01:13:31,829 --> 01:13:35,290 and it sort of runs and runs, and it just sort of computes... 1158 01:13:35,415 --> 01:13:38,627 and we happen somehow by accident to find ourselves in this thing. 1159 01:13:38,752 --> 01:13:41,797 But I don't think that's a very fruitful... 1160 01:13:41,922 --> 01:13:45,342 or helpful way of looking at the universe. 1161 01:13:45,467 --> 01:13:48,345 I think that there is something much deeper about it. 1162 01:13:50,681 --> 01:13:54,560 In real time, the time in which we live... 1163 01:13:54,685 --> 01:13:58,647 the universe has two possible destinies: 1164 01:13:58,772 --> 01:14:02,442 It may continue to expand forever... 1165 01:14:04,236 --> 01:14:07,406 or it may recollapse and come to an end... 1166 01:14:07,531 --> 01:14:09,491 at the Big Crunch. 1167 01:14:11,326 --> 01:14:14,246 It would be rather like the Big Bang... 1168 01:14:14,371 --> 01:14:16,373 but in reverse. 1169 01:14:18,292 --> 01:14:22,212 I now believe that the universe will come to an end... 1170 01:14:22,379 --> 01:14:24,506 at the Big Crunch. 1171 01:14:25,632 --> 01:14:28,719 I do, however, have certain advantages... 1172 01:14:28,844 --> 01:14:31,388 over many other prophets of doom. 1173 01:14:33,765 --> 01:14:37,227 Whatever happens ten billion years from now... 1174 01:14:37,352 --> 01:14:41,106 I don't expect to be around to be proved wrong. 1175 01:14:43,817 --> 01:14:48,280 Of all the pictures that I know... 1176 01:14:48,405 --> 01:14:51,241 the simplest of any cosmology... 1177 01:14:51,366 --> 01:14:54,578 is that in which the universe is closed... 1178 01:14:54,745 --> 01:14:56,872 has a finite lifetime... 1179 01:14:56,997 --> 01:15:00,250 and collapses with the same kind of collapse... 1180 01:15:00,375 --> 01:15:02,252 that a black hole does. 1181 01:15:04,546 --> 01:15:06,882 If it should turn out that indeed... 1182 01:15:07,007 --> 01:15:10,093 the universe is limited in its life... 1183 01:15:12,262 --> 01:15:15,432 how is that different from the life... 1184 01:15:15,599 --> 01:15:17,434 of each one of us? 1185 01:15:27,277 --> 01:15:29,780 On the evening of Tuesday, March 5th... 1186 01:15:29,905 --> 01:15:32,366 at about 10:45... 1187 01:15:32,491 --> 01:15:35,452 I was returning to my flat in Pinehurst. 1188 01:15:37,955 --> 01:15:39,873 It was dark and raining. 1189 01:15:41,667 --> 01:15:43,794 I came up to Grange Road... 1190 01:15:43,961 --> 01:15:46,255 and saw headlights approaching... 1191 01:15:46,380 --> 01:15:49,132 but judged that they were far enough away... 1192 01:15:49,258 --> 01:15:51,343 that I could cross safely. 1193 01:15:54,138 --> 01:15:57,683 The vehicle must have been traveling very fast... 1194 01:15:57,808 --> 01:16:01,395 for when I got just past the middle of the road... 1195 01:16:01,520 --> 01:16:04,273 my nurse screamed, "Look out!" 1196 01:16:06,692 --> 01:16:08,986 I heard tires skidding... 1197 01:16:09,111 --> 01:16:12,906 and my wheelchair was struck a tremendous blow in the back. 1198 01:16:14,992 --> 01:16:16,869 I ended up in the road... 1199 01:16:16,994 --> 01:16:20,372 with my legs over the remains of the wheelchair. 1200 01:16:22,166 --> 01:16:25,127 The accident destroyed my wheelchair... 1201 01:16:25,252 --> 01:16:27,671 and damaged my computer system... 1202 01:16:27,796 --> 01:16:29,715 with which I communicate. 1203 01:16:32,217 --> 01:16:35,846 I required 13 stitches in my head... 1204 01:16:37,514 --> 01:16:42,019 but I was able to go back to work several days later. 1205 01:16:47,274 --> 01:16:50,861 The memories I have are very much... 1206 01:16:51,028 --> 01:16:52,905 kind of... 1207 01:16:53,030 --> 01:16:55,991 visual pictures of what Stephen was... 1208 01:16:56,116 --> 01:17:00,287 of seeing Stephen in certain situations. 1209 01:17:00,412 --> 01:17:03,415 He was always moving. 1210 01:17:03,540 --> 01:17:05,209 Always. 1211 01:17:05,334 --> 01:17:07,294 Well, hardly ever still. 1212 01:17:08,378 --> 01:17:12,716 It was the same thing about his face and gesture... 1213 01:17:12,841 --> 01:17:15,135 which he used a great deal, I should say... 1214 01:17:15,260 --> 01:17:18,013 but it's only memory. 1215 01:17:19,306 --> 01:17:22,017 I found some photographs recently... 1216 01:17:22,142 --> 01:17:25,729 which reminded me of the general look of everybody... 1217 01:17:25,854 --> 01:17:29,817 and I must say Stephen looked very much like he does now... 1218 01:17:31,068 --> 01:17:34,029 if one thinks of him like that. 1219 01:17:40,536 --> 01:17:43,664 He does believe very intensely... 1220 01:17:43,789 --> 01:17:49,336 in the almost infinite possibility of the human mind. 1221 01:17:49,711 --> 01:17:51,964 You have to find out what you can't know... 1222 01:17:52,089 --> 01:17:54,091 before you know you can't, don't you? 1223 01:17:54,258 --> 01:17:58,595 So I don't think that thought should be restricted at all. 1224 01:17:58,762 --> 01:18:02,933 Why shouldn't you go on thinking about the unthinkable? 1225 01:18:03,058 --> 01:18:05,102 Somebody's got to start sometime. 1226 01:18:05,269 --> 01:18:08,689 Think how many things were unthinkable a century ago... 1227 01:18:08,814 --> 01:18:10,858 and yet people have thought them. 1228 01:18:10,983 --> 01:18:13,193 And often they also seemed quite unpractical. 1229 01:18:14,695 --> 01:18:17,364 Not all the things Stephen says probably... 1230 01:18:17,489 --> 01:18:19,658 are to be taken as gospel truth. 1231 01:18:19,783 --> 01:18:22,244 He's a searcher. He's looking for things. 1232 01:18:22,369 --> 01:18:26,123 And sometimes he probably talks nonsense. Well, don't we all? 1233 01:18:26,290 --> 01:18:28,500 But the point is... 1234 01:18:29,626 --> 01:18:31,920 people must think. 1235 01:18:32,045 --> 01:18:33,922 People must go on thinking. 1236 01:18:34,047 --> 01:18:37,468 They must try to extend the boundaries of knowledge... 1237 01:18:37,593 --> 01:18:40,095 and they don't sometimes even know where to start. 1238 01:18:41,972 --> 01:18:45,100 You don't know where the boundaries are, do you? 1239 01:18:45,225 --> 01:18:48,479 You don't know what your taking-off point is. 1240 01:18:57,571 --> 01:19:01,325 If we do discover a complete theory of the universe... 1241 01:19:01,450 --> 01:19:03,660 it should in time be understandable... 1242 01:19:03,827 --> 01:19:06,580 in broad principle by everyone... 1243 01:19:06,705 --> 01:19:09,249 not just a few scientists. 1244 01:19:14,004 --> 01:19:15,964 Then we shall all... 1245 01:19:16,089 --> 01:19:20,511 philosophers, scientists, and just ordinary people... 1246 01:19:20,677 --> 01:19:24,848 be able to take part in the discussion of why it is... 1247 01:19:25,015 --> 01:19:28,519 that we and the universe exist. 1248 01:19:32,064 --> 01:19:34,858 If we find the answer to that... 1249 01:19:34,983 --> 01:19:37,236 it would be the ultimate triumph... 1250 01:19:37,361 --> 01:19:39,321 of human reason... 1251 01:19:42,366 --> 01:19:45,035 for then we would know... 1252 01:19:45,160 --> 01:19:47,538 the mind of God. 1252 01:19:48,305 --> 01:19:54,651 Support us and become VIP member to remove all ads from www.OpenSubtitles.org