1 00:00:13,300 --> 00:00:15,874 A century ago, the great polar explorers 2 00:00:15,975 --> 00:00:19,359 were pushing further and further towards the coldest places on Earth: 3 00:00:19,617 --> 00:00:21,600 the north and south poles. 4 00:00:26,840 --> 00:00:29,439 The competition to reach these goals was matched 5 00:00:29,440 --> 00:00:33,280 by a less publicised but equally daunting scientific endeavour: 6 00:00:33,717 --> 00:00:36,840 the attempt to reach the coldest point in the universe: 7 00:00:37,259 --> 00:00:39,000 absolute zero. 8 00:00:44,117 --> 00:00:47,008 This mysterious barrier was a physical paradox 9 00:00:47,009 --> 00:00:49,781 as tantalizing as the speed limit of light, 10 00:00:49,882 --> 00:00:51,914 which can also never be exceeded. 11 00:00:54,979 --> 00:00:56,705 It was a frontier so enticing 12 00:00:56,706 --> 00:00:59,349 that rival physicists from all over Europe 13 00:00:59,350 --> 00:01:02,518 begun a race towards this absolute limit of cold. 14 00:01:04,640 --> 00:01:06,914 This is a story of showmanship, 15 00:01:07,514 --> 00:01:08,399 setbacks, 16 00:01:08,400 --> 00:01:10,114 rivalry and despair. 17 00:01:10,614 --> 00:01:11,914 The stakes were high. 18 00:01:12,614 --> 00:01:16,560 For the winner there was glory and the chance of the Nobel Prize. 19 00:01:17,014 --> 00:01:22,114 For the loser, the prospect of being a forgotten foot soldier of science. 20 00:01:46,400 --> 00:01:49,040 When explorers ventured into the Antarctic 21 00:01:49,180 --> 00:01:51,840 they experienced some of the coldest temperatures on Earth, 22 00:01:52,020 --> 00:01:55,480 reaching down to -80 °C. 23 00:01:57,100 --> 00:02:00,660 But this was nothing compared to the ultimate limit of temperature, 24 00:02:00,760 --> 00:02:02,260 absolute zero, 25 00:02:02,360 --> 00:02:05,760 at around -273 degrees. 26 00:02:10,019 --> 00:02:12,799 Only in a laboratory, by liquifying gases 27 00:02:12,800 --> 00:02:14,859 could adventurers take the first steps 28 00:02:14,860 --> 00:02:16,519 towards this Holy Grail, 29 00:02:16,740 --> 00:02:20,380 a place utterly drained of all thermal energy. 30 00:02:36,502 --> 00:02:39,500 Among the front-runners in the race towards absolute zero 31 00:02:39,520 --> 00:02:43,400 was James Dewar, a professor at the Royal Institution in London. 32 00:02:43,779 --> 00:02:45,760 "- It will be the greatest achievement of our age... " 33 00:02:45,880 --> 00:02:48,598 In 1891, he gave one of his celebrated 34 00:02:48,599 --> 00:02:50,239 Friday night public lectures 35 00:02:50,240 --> 00:02:53,879 on the wonders of the super cold, to celebrate the centenary 36 00:02:53,960 --> 00:02:56,700 of his great predecessor, Michael Faraday. 37 00:02:59,800 --> 00:03:02,619 "... The descent to a temperature within 5 degrees of zero 38 00:03:03,500 --> 00:03:06,799 would open up new vistas of scientific inquiry, 39 00:03:07,400 --> 00:03:09,080 which would add immensely to our knowledge 40 00:03:09,159 --> 00:03:10,899 of the properties of matter." 41 00:03:14,759 --> 00:03:19,700 (Simon Schaffer) James Dewar is a canny and I think very ambitious, 42 00:03:20,080 --> 00:03:22,878 practically-minded Scottish scientist. 43 00:03:22,879 --> 00:03:25,520 He could really show, both his colleagues 44 00:03:26,480 --> 00:03:28,435 and the fee-paying audiences 45 00:03:28,436 --> 00:03:33,077 who came to this inmensely succesful brilliantly engineered lectures, 46 00:03:33,378 --> 00:03:35,256 some of the secrets of nature. 47 00:03:36,820 --> 00:03:37,879 Take this rubber ball... 48 00:03:39,999 --> 00:03:41,680 It bounces well, I think you'll agree. 49 00:03:42,599 --> 00:03:43,599 But let's see what happens 50 00:03:43,680 --> 00:03:46,960 after a few seconds' immersion in liquid oxygen. 51 00:03:52,360 --> 00:03:56,160 Dewar invented the vacuum flask to carry out his research, 52 00:03:56,161 --> 00:03:58,798 and it's still called "a Dewar" to this day. 53 00:04:01,060 --> 00:04:03,080 Now, let's see what happens. 54 00:04:09,328 --> 00:04:13,531 (Kostas Gavroglu) This phantasmagoric aspect of science 55 00:04:13,832 --> 00:04:18,202 always helped science to be accepted by the public. 56 00:04:18,203 --> 00:04:22,373 Though it is a little mystifying, it did play a role 57 00:04:22,374 --> 00:04:26,377 of having society, having the public accept 58 00:04:26,478 --> 00:04:30,314 that these weird people in the laboratories 59 00:04:30,315 --> 00:04:34,852 are doing truly interesting, if not magical things. 60 00:04:46,960 --> 00:04:50,520 James Dewar's life was defined by the cold. 61 00:04:51,620 --> 00:04:55,200 As a boy, he used to skate on a frozen pond in Scotland. 62 00:04:55,720 --> 00:04:59,390 He claimed in later life that his most formative early experience 63 00:04:59,440 --> 00:05:01,840 resulted from an accident on the ice. 64 00:05:07,760 --> 00:05:09,190 (Tom Shachtman) After Dewar fell through the ice. 65 00:05:09,240 --> 00:05:10,584 He was rescued 66 00:05:10,885 --> 00:05:14,798 but when he got home they discovered that he had rheumatic fever, 67 00:05:14,960 --> 00:05:17,365 which put him in bed for eight months. 68 00:05:17,366 --> 00:05:21,870 And he was in danger of having his limbs atrophy, with pulsy 69 00:05:21,920 --> 00:05:23,981 and so the village joiner set him tasks 70 00:05:24,082 --> 00:05:27,678 to develop his limbs, and especially his hands, 71 00:05:27,780 --> 00:05:31,219 and one of the tasks was to make a violin. 72 00:05:31,360 --> 00:05:33,800 And he developed a great deal of mechanical aptitude 73 00:05:34,200 --> 00:05:36,360 which stood him in very good stead in later years 74 00:05:36,560 --> 00:05:38,800 when he had to create apparatuses for his uses. 75 00:05:41,400 --> 00:05:43,640 Dewar's dream was to take on the mantle 76 00:05:43,660 --> 00:05:47,720 of the Royal Institution's greatest scientist, Michael Faraday. 77 00:05:53,200 --> 00:05:55,960 Seventy years earlier, Faraday had done experiments 78 00:05:56,039 --> 00:05:57,300 showing that under pressure, 79 00:05:57,320 --> 00:06:00,640 gases like chlorine and ammonia liquify. 80 00:06:00,940 --> 00:06:05,040 And as this liquids evaporate, their temperature drops dramatically. 81 00:06:08,180 --> 00:06:11,280 Faraday was curious to see if this method of pressurizing 82 00:06:11,286 --> 00:06:14,879 gases into liquids could be used for all gases. 83 00:06:17,420 --> 00:06:20,759 But some gases, what he called the "permanent" gases 84 00:06:20,860 --> 00:06:24,200 would not liquify, no matter how much pressure he applied. 85 00:06:24,420 --> 00:06:26,840 So he abandoned this line of research. 86 00:06:29,720 --> 00:06:32,259 "Faraday's was a mind full of subtle powers, 87 00:06:32,520 --> 00:06:34,840 of divination into nature's secrets... 88 00:06:36,080 --> 00:06:40,239 and although unable to liquify the permanent gases, 89 00:06:40,720 --> 00:06:43,180 he expressed faith in the potentialities 90 00:06:43,720 --> 00:06:45,740 of experimental inquiry. 91 00:06:47,440 --> 00:06:50,560 The lowest point of temperature attained by Faraday 92 00:06:51,440 --> 00:06:54,520 was -130 degrees centigrade." 93 00:06:57,620 --> 00:07:03,200 For over 30 years noone could reach a lower temperature than -130 °C. 94 00:07:03,520 --> 00:07:08,520 Absolute zero remained an elusive and very distant goal. 95 00:07:10,640 --> 00:07:14,040 Now, Michael Faraday, in the early to mid 19th century, 96 00:07:14,240 --> 00:07:20,160 had left a kind of for-long frontier for physicists and chemists: 97 00:07:20,520 --> 00:07:23,960 what he called the permanent gases (hydrogen, nitrogen, oxygen), 98 00:07:24,140 --> 00:07:27,960 which no means whatsoever seemed to be able to liquify. 99 00:07:28,700 --> 00:07:32,800 And this was a kind of "no man's land" which one could not cross. 100 00:07:33,340 --> 00:07:35,615 And that was a standing challenge 101 00:07:36,016 --> 00:07:39,038 for the scientists of the later 19th century: 102 00:07:39,140 --> 00:07:45,620 "It must be possible to turn these gases into pure liquids." 103 00:07:48,400 --> 00:07:52,600 It was not until 1873 that a Dutch theoretical physicist, 104 00:07:52,620 --> 00:07:54,880 Van Der Waals, finally explained 105 00:07:54,960 --> 00:07:57,480 why these gases were not liquifying. 106 00:07:58,645 --> 00:08:02,719 By estimating the size of molecules and the forces between them, 107 00:08:02,720 --> 00:08:05,540 he showed that to liquify these gases using pressure, 108 00:08:05,599 --> 00:08:09,280 they each had to be cooled below a critical temperature. 109 00:08:14,080 --> 00:08:16,339 At last, he had shown the way to liquify 110 00:08:16,340 --> 00:08:18,980 the so-called permanent gases. 111 00:08:23,720 --> 00:08:27,359 Oxygen was first, and then nitrogen, 112 00:08:27,360 --> 00:08:32,140 reaching a new low temperature of almost -200 °C. 113 00:08:34,160 --> 00:08:38,420 "Only the last of the permanent gases remains to be liquified: 114 00:08:39,920 --> 00:08:45,260 hydrogen, in the vicinity of -250 °C. 115 00:08:46,440 --> 00:08:48,900 It will be the greatest achievement of our age, 116 00:08:49,119 --> 00:08:52,099 a triumph of science." 117 00:08:55,160 --> 00:08:57,859 Dewar was determined to be the first to ascend 118 00:08:57,920 --> 00:09:00,040 what he called "Mount Hydrogen". 119 00:09:00,791 --> 00:09:02,637 But he was not alone. 120 00:09:09,020 --> 00:09:10,879 The competitor Dewar feared most 121 00:09:11,160 --> 00:09:14,419 was a brilliant Dutchman, Heike Kamerlingh Onnes. 122 00:09:17,239 --> 00:09:20,460 Kamerlingh Onnes was younger than Dewar 123 00:09:21,059 --> 00:09:25,600 and to a certain extent looked up to the Scotsman as his senior. 124 00:09:26,560 --> 00:09:28,160 Dewar didn't have the same, 125 00:09:28,240 --> 00:09:30,639 if you'll pardon the expression, "warm feelings," 126 00:09:30,640 --> 00:09:34,240 towards his rival in the race for cold. 127 00:09:36,442 --> 00:09:38,710 Dewar recognized that Kamerlingh Onnes 128 00:09:38,711 --> 00:09:41,199 had a new radical approach to science 129 00:09:41,200 --> 00:09:44,440 and was planning an industrial scale lab. 130 00:09:45,385 --> 00:09:47,546 (Dirk van Delft) When Onnes took over the physics laboratory in Leiden, 131 00:09:47,547 --> 00:09:48,997 he was only 29 years old. 132 00:09:49,759 --> 00:09:51,799 And, well, he gave his inaugural address 133 00:09:51,800 --> 00:09:53,760 here in this lecture room, 134 00:09:53,939 --> 00:09:56,440 the big lecture room of the Academy Building of Leiden University, 135 00:09:56,740 --> 00:09:58,120 and it was all there. 136 00:09:58,220 --> 00:10:00,759 He was explaining what to do in the next years, 137 00:10:00,920 --> 00:10:04,120 and he was talking about liquifying gases, 138 00:10:04,240 --> 00:10:07,440 making Dutch physics famous abroad, and well, 139 00:10:08,119 --> 00:10:11,880 it was amazing how farsighted all those visions were. 140 00:10:15,399 --> 00:10:18,340 Kamerlingh Onnes' lab was more like a factory. 141 00:10:18,440 --> 00:10:20,959 He recruited instrument makers, glassblowers, 142 00:10:20,960 --> 00:10:23,422 and a cadre of young assistants who became known 143 00:10:23,423 --> 00:10:26,740 as "blue boys" because of their blue lab coats. 144 00:10:27,027 --> 00:10:29,518 Later, he set up a technical training school, 145 00:10:29,519 --> 00:10:31,980 which still exists to this day. 146 00:10:37,040 --> 00:10:39,960 Dewar and Onnes could not have been more different. 147 00:10:40,680 --> 00:10:43,260 Dewar was very secretive about his work, 148 00:10:43,440 --> 00:10:46,219 hiding crucial bits of apparatus from public view 149 00:10:46,260 --> 00:10:47,599 before his lectures. 150 00:10:49,160 --> 00:10:51,540 Onnes on the other hand, openly shared his lab's 151 00:10:51,560 --> 00:10:53,800 steady progress in a monthly journal. 152 00:10:54,320 --> 00:10:57,440 Onnes was the tortoise to Dewar's hare. 153 00:10:59,100 --> 00:11:02,660 In the case of Dewar, you had a brilliant experimenter, 154 00:11:02,759 --> 00:11:06,020 a person who could actually build the instruments himself, 155 00:11:06,140 --> 00:11:10,140 and a person who really believed in the brute force approach, 156 00:11:10,160 --> 00:11:12,759 and that is, have your instruments, 157 00:11:13,000 --> 00:11:16,020 set up your experiment, and try as hard as you can, 158 00:11:16,140 --> 00:11:19,260 and then, you'll get the results you want to get. 159 00:11:19,800 --> 00:11:22,160 In the case of Kamerlingh Onnes, 160 00:11:22,399 --> 00:11:23,999 you have a totally different approach. 161 00:11:26,399 --> 00:11:30,678 He's the beginning of what later on 162 00:11:30,679 --> 00:11:32,320 was known as "big science". 163 00:11:35,320 --> 00:11:38,680 Unlike Dewar, Onnes thought detailed calculations 164 00:11:38,800 --> 00:11:42,719 based on theory were vital before embarking on experiments. 165 00:11:42,919 --> 00:11:45,879 He was a disciple and close friend of Van Der Waals, 166 00:11:45,999 --> 00:11:48,140 whose theory had helped solve the problem 167 00:11:48,160 --> 00:11:50,320 of liquifying permanent gases. 168 00:11:56,879 --> 00:11:58,239 Though their approaches were different, 169 00:11:58,800 --> 00:12:00,239 Kamerlingh Onnes and Dewar 170 00:12:00,320 --> 00:12:04,160 used a similar process in their attempts to liquify hydrogen. 171 00:12:06,119 --> 00:12:09,640 Their idea was to go step-by-step down a cascade 172 00:12:09,879 --> 00:12:11,440 using a series of different gases 173 00:12:11,619 --> 00:12:14,980 that liquify at lower and lower temperatures. 174 00:12:18,399 --> 00:12:20,560 By applying pressure on the first gas 175 00:12:21,040 --> 00:12:24,440 and releasing it into a cooling coil submerged in a coolant, 176 00:12:24,879 --> 00:12:26,220 it liquifies. 177 00:12:27,920 --> 00:12:30,399 When this liquified gas enters the next vessel, 178 00:12:30,800 --> 00:12:34,240 it becomes the coolant for the 2nd gas in the chain. 179 00:12:35,480 --> 00:12:37,138 When the next gas is pressurized 180 00:12:37,139 --> 00:12:38,879 and passes through the inner coil, 181 00:12:39,360 --> 00:12:42,999 it liquifies and is at an even lower temperature. 182 00:12:44,160 --> 00:12:48,040 The 2nd liquid goes on to cool the next gas and so on. 183 00:12:48,480 --> 00:12:53,120 Step by step, the liquified gases become colder and colder. 184 00:12:53,340 --> 00:12:56,599 Each one is used to lower the temperature of the next gas 185 00:12:56,620 --> 00:12:59,320 sufficiently for it to liquify. 186 00:12:59,860 --> 00:13:03,139 In the final stage, where hydrogen gas is cooled, 187 00:13:03,140 --> 00:13:06,040 the idea was to put it under enormous pressure, 188 00:13:06,160 --> 00:13:09,239 180 times atmospheric pressure, 189 00:13:09,440 --> 00:13:12,680 and then suddenly release it through a valve. 190 00:13:14,160 --> 00:13:16,320 This would trigger a massive drop in temperature, 191 00:13:16,440 --> 00:13:19,879 sufficient to turn hydrogen gas into liquid hydrogen 192 00:13:19,999 --> 00:13:26,320 at -252 degrees, just 21 degrees above absolute zero. 193 00:13:27,440 --> 00:13:31,160 Here was the risky bit because his apparatus was 194 00:13:32,120 --> 00:13:35,319 going down in temperature, getting very, very cold, 195 00:13:35,420 --> 00:13:37,719 so very fragile, quite easy to fracture. 196 00:13:38,199 --> 00:13:39,440 While at the same time, 197 00:13:39,519 --> 00:13:42,040 the pressures he was working at were very, very high, 198 00:13:42,160 --> 00:13:43,760 so the possibility of explosion. 199 00:13:45,519 --> 00:13:49,840 He took the most amazing risks, both with himself 200 00:13:50,040 --> 00:13:52,620 - he was a lion of a man in terms of courage - 201 00:13:53,040 --> 00:13:54,519 and with those around him. 202 00:13:56,160 --> 00:13:57,939 All the equipment he was working with 203 00:13:58,220 --> 00:14:00,079 could have crumbled or blown up 204 00:14:00,700 --> 00:14:03,240 and more than occasionally, it did. 205 00:14:06,699 --> 00:14:08,759 Dewar had many explosions in his lab. 206 00:14:09,119 --> 00:14:11,399 Several times, assistants lost their eyes 207 00:14:11,519 --> 00:14:14,119 as shards of glass catapulted through the air. 208 00:14:15,240 --> 00:14:17,840 In the notebook he actually writes, 209 00:14:17,920 --> 00:14:21,160 jots down many details of what happened to the apparatus, 210 00:14:21,339 --> 00:14:23,219 but not what happened to his assistants. 211 00:14:23,680 --> 00:14:26,159 So somehow you get the impression that apparatus 212 00:14:26,160 --> 00:14:27,920 is more important than the assistants. 213 00:14:29,620 --> 00:14:31,662 (Frank James) Well, the assistants seemed to have been quite loyal to him 214 00:14:31,663 --> 00:14:32,876 'cause he stayed working. 215 00:14:33,220 --> 00:14:35,760 I mean, if you look at the picture of Dewar lecturing 216 00:14:35,860 --> 00:14:37,010 there are two assistants. 217 00:14:37,011 --> 00:14:41,161 There one of whom has lost his eye but the painter manages to portray him 218 00:14:41,162 --> 00:14:43,899 with his lost eye facing the other way 219 00:14:43,900 --> 00:14:46,999 so you don't actually see it in the picture. 220 00:14:47,000 --> 00:14:50,518 So it clearly there was something going for Dewar with his assistants 221 00:14:50,519 --> 00:14:52,159 in that he kept that sort of 222 00:14:52,160 --> 00:14:56,080 loyalty in a way that would be almost inconceivable in the modern world. 223 00:15:02,919 --> 00:15:06,959 Over in Leiden, Onnes was facing anxious city officials 224 00:15:06,960 --> 00:15:09,439 who were so worried about the risk of explosions 225 00:15:09,440 --> 00:15:11,720 that they ordered the lab to be shut down. 226 00:15:17,119 --> 00:15:19,879 Dewar wrote a letter of protest on behalf of Onnes 227 00:15:20,160 --> 00:15:23,160 but the Leiden lab remained closed for 2 years. 228 00:15:29,440 --> 00:15:31,899 (Dirk van Delft) Onnes had to wait and to wait and to wait. 229 00:15:32,759 --> 00:15:35,520 Dewar was already starting his liquifying hydrogen, 230 00:15:35,920 --> 00:15:38,519 and Onnes had the apparatus to do so too, 231 00:15:38,520 --> 00:15:39,740 but he just couldn't start, 232 00:15:39,840 --> 00:15:42,759 so we had lost the battle before it was even begun. 233 00:15:50,440 --> 00:15:51,799 The year is 1898. 234 00:15:52,000 --> 00:15:54,499 Dewar has been working on trying to liquify hydrogen 235 00:15:54,600 --> 00:15:56,979 for more than 20 years, and he's finally ready 236 00:15:56,999 --> 00:15:59,100 to make the final assault on Mount Hydrogen. 237 00:15:59,999 --> 00:16:03,040 By using liquid oxygen, they brought down the temperature 238 00:16:03,160 --> 00:16:06,759 of the hydrogen gas to -200 °C. 239 00:16:07,680 --> 00:16:11,040 They increased the pressure till the vessels were almost bursting 240 00:16:11,239 --> 00:16:14,320 and then opened the last valve in the cascade. 241 00:16:17,560 --> 00:16:20,399 (as James Dewar) "Shortly after starting, the nozzle plugged, 242 00:16:20,860 --> 00:16:22,680 but it got free by good luck 243 00:16:23,800 --> 00:16:27,100 and almost immediately drops of liquid began to fall 244 00:16:27,320 --> 00:16:31,199 and soon accumulated 20 cubic centimeters." 245 00:16:32,320 --> 00:16:34,460 Dewar had liquified hydrogen, 246 00:16:34,759 --> 00:16:37,699 the last of the so-called permanent gases. 247 00:16:37,880 --> 00:16:41,079 To prove it, he took a small tube of liquid oxygen 248 00:16:41,239 --> 00:16:43,160 and plunged it into the new liquid. 249 00:16:45,440 --> 00:16:48,419 Instantly, the liquid oxygen froze solid. 250 00:16:48,560 --> 00:16:50,160 Now he was convinced. 251 00:16:51,800 --> 00:16:54,160 He had produced the coldest liquid on Earth 252 00:16:54,519 --> 00:16:58,360 and had come closer to absolute zero than anyone else. 253 00:17:01,040 --> 00:17:02,780 (Tom Shachtman) Dewar thought that he had done 254 00:17:02,800 --> 00:17:04,880 the most amazing feat of science in the world, 255 00:17:05,120 --> 00:17:07,560 that he would be immediately celebrated for it 256 00:17:08,039 --> 00:17:10,039 and get whatever prizes there were available. 257 00:17:10,880 --> 00:17:12,380 And that didn't happen. 258 00:17:12,940 --> 00:17:17,358 I think for Dewar, it was the ambition of a mountaineer. 259 00:17:17,559 --> 00:17:20,320 You've climbed the highest mountain peak 260 00:17:20,440 --> 00:17:23,880 that you can see in the range around you, 261 00:17:24,039 --> 00:17:25,680 and just as you get to the top of the peak, 262 00:17:25,759 --> 00:17:28,200 there's an even higher mountain just beyond. 263 00:17:30,960 --> 00:17:33,038 That mountain was helium, 264 00:17:33,239 --> 00:17:35,619 a recently discovered inert gas. 265 00:17:40,039 --> 00:17:43,120 Van Der Waal's theory predicted helium would liquify 266 00:17:43,200 --> 00:17:45,279 at an even lower temperature than hydrogen, 267 00:17:45,560 --> 00:17:49,059 at around 5 degrees above absolute zero. 268 00:17:51,759 --> 00:17:54,799 Now all Dewar had to do was obtain some. 269 00:17:54,980 --> 00:17:56,540 It should not have been difficult. 270 00:17:56,619 --> 00:17:59,199 The two chemists who had discovered the inert gases, 271 00:17:59,200 --> 00:18:01,440 Lord Rayleigh and William Ramsay, 272 00:18:01,519 --> 00:18:04,120 often worked together in the lab next door. 273 00:18:06,360 --> 00:18:09,600 Unfortunately, Dewar had made enemies of both of them 274 00:18:09,680 --> 00:18:13,959 by publicly criticizing their science and belittling their achievements, 275 00:18:13,960 --> 00:18:17,019 so they had no desire to share their helium. 276 00:18:18,240 --> 00:18:21,120 Kamerlingh Onnes was faced with the same problem as Dewar, 277 00:18:21,200 --> 00:18:23,959 which was: Where can I get a supply of helium gas? 278 00:18:24,180 --> 00:18:25,939 And he actually asked Dewar 279 00:18:26,180 --> 00:18:29,039 to try and collaborate with him too, and Dewar said, 280 00:18:29,320 --> 00:18:31,600 I'm having such a problem getting the gas by myself, 281 00:18:31,680 --> 00:18:34,640 I can't possibly give you any. I'd like to, but I can't. 282 00:18:35,239 --> 00:18:37,600 Eventually, each found a supply, 283 00:18:37,839 --> 00:18:41,140 but Onnes' industrial approach paid dividends. 284 00:18:41,240 --> 00:18:42,919 After 3 years, he had amassed 285 00:18:42,920 --> 00:18:45,400 enough helium gas to begin experiments. 286 00:18:45,759 --> 00:18:49,140 The tortoise was beginning to pull away from the hare. 287 00:18:49,440 --> 00:18:52,613 The liquefaction of these gases 288 00:18:52,614 --> 00:18:56,839 has become a matter of enormous pride and prestige for Dewar. 289 00:18:57,160 --> 00:19:01,240 But pretty quickly he run out of resources. 290 00:19:01,600 --> 00:19:06,348 He was reaching the limit of what the budget would bear 291 00:19:06,349 --> 00:19:07,678 at the Royal Institution 292 00:19:07,980 --> 00:19:11,680 and the helium supplies dried up. 293 00:19:13,980 --> 00:19:17,558 One day, when they were in the mid of working with gas of helium 294 00:19:17,959 --> 00:19:19,494 an assistant in Dewar's lab 295 00:19:19,595 --> 00:19:22,037 turned the knob to the left instead of to the right, 296 00:19:22,520 --> 00:19:25,160 the whole canister of the gas escaped into the air 297 00:19:25,240 --> 00:19:28,458 and they had 6 months when they couldn't do any work whatsoever. 298 00:19:28,559 --> 00:19:30,119 Dewar was furied. 299 00:19:38,160 --> 00:19:41,596 (Kostas Gavroglu) At one point, Dewar writes to Kamerlingh Onnes 300 00:19:41,597 --> 00:19:45,719 telling him that he is not in the race anymore. 301 00:19:45,900 --> 00:19:48,960 He thinks that the problems for liquifying helium 302 00:19:49,039 --> 00:19:53,880 are such that he's not able to complete the job. 303 00:19:56,120 --> 00:19:57,839 The battlefields of science 304 00:19:58,519 --> 00:20:00,719 are the centers of a perpetual warfare 305 00:20:01,700 --> 00:20:04,579 in which there is no hope of a final victory. 306 00:20:06,200 --> 00:20:07,719 To serve in the scientific army, 307 00:20:08,440 --> 00:20:10,740 to have shown the initiative 308 00:20:11,279 --> 00:20:14,200 is enough to satisfy the legitimate ambition 309 00:20:14,820 --> 00:20:18,720 of every earnest student of nature. 310 00:20:20,380 --> 00:20:21,160 Thank you. 311 00:20:35,318 --> 00:20:37,759 In the summer of 1908, Onnes summoned 312 00:20:37,839 --> 00:20:40,360 his chief assistant, Flim, from across the river. 313 00:20:41,440 --> 00:20:44,880 They were finally ready to try to liquify helium. 314 00:20:51,880 --> 00:20:53,880 At 5:45 on the morning of July the 10th, 315 00:20:53,939 --> 00:20:55,759 he assembled his team at the lab. 316 00:20:56,360 --> 00:20:58,759 They had rehearsed the drill many times before. 317 00:20:59,880 --> 00:21:01,839 Leiden was a small university town 318 00:21:02,160 --> 00:21:05,880 and the word quickly spread that this was the big day. 319 00:21:08,200 --> 00:21:10,019 It took until lunchtime to make sure 320 00:21:10,020 --> 00:21:12,880 the apparatus was purged of the last traces of air. 321 00:21:13,560 --> 00:21:16,239 By 3 in the afternoon, work was so intense 322 00:21:16,500 --> 00:21:18,200 that when his wife arrived with lunch, 323 00:21:18,360 --> 00:21:21,799 he asked her to feed him so he didn't have to stop work. 324 00:21:22,600 --> 00:21:24,640 This was a man obsessed. 325 00:21:26,000 --> 00:21:27,279 At 6:30 in the evening, 326 00:21:27,440 --> 00:21:30,719 the temperature began to drop below that of liquid hydrogen. 327 00:21:32,339 --> 00:21:33,720 It's getting very late in the day 328 00:21:33,820 --> 00:21:36,798 and the team is down to its last bottle of hydrogen 329 00:21:36,799 --> 00:21:38,828 and if they can't liquify helium now 330 00:21:39,129 --> 00:21:41,317 they're going to have to wait for months to try again 331 00:21:41,659 --> 00:21:46,519 and the temperature gauge is stuck at five degrees above absolute zero. 332 00:21:46,880 --> 00:21:50,120 And Onnes doesn't know why this is, and a colleague comes in 333 00:21:50,400 --> 00:21:52,360 and he suggests that that means 334 00:21:52,680 --> 00:21:54,980 maybe they've actually succeeded and they don't even know it yet. 335 00:21:55,439 --> 00:21:58,419 So Onnes takes an electric lamp type thing and he goes 336 00:21:58,480 --> 00:22:01,540 underneath the apparatus and looks, and sure enough, 337 00:22:01,920 --> 00:22:06,120 there in the vial is this liquid sitting there quietly. 338 00:22:06,200 --> 00:22:07,759 It's liquified helium. 339 00:22:09,319 --> 00:22:15,839 They had reached -268 °C, just 5 degrees above absolute zero 340 00:22:15,880 --> 00:22:18,360 and finally produced liquid helium. 341 00:22:19,719 --> 00:22:21,200 This monumental achievement 342 00:22:21,279 --> 00:22:24,279 eventually won Onnes the Nobel Prize. 343 00:22:27,759 --> 00:22:29,119 When James Dewar heard 344 00:22:29,120 --> 00:22:31,560 that he had lost the race to Kamerlingh Onnes, 345 00:22:31,839 --> 00:22:34,120 it reignited a festering resentment. 346 00:22:34,880 --> 00:22:37,960 Dewar berated his long-suffering assistant, Lennox, 347 00:22:38,279 --> 00:22:40,239 for failing to provide enough helium. 348 00:22:42,039 --> 00:22:44,600 Only this time, Lennox had had enough. 349 00:22:45,139 --> 00:22:47,366 He walked out of the Royal Institution, 350 00:22:47,367 --> 00:22:50,587 vowing never to return until Dewar was dead. 351 00:22:51,088 --> 00:22:52,358 And he kept his word. 352 00:22:54,040 --> 00:22:57,880 For Dewar, it was the end of his low temperature research. 353 00:22:59,139 --> 00:23:00,930 He must've been incredibly irritated 354 00:23:00,960 --> 00:23:02,743 and knowing Dewar he must... 355 00:23:02,744 --> 00:23:04,937 one can imagine that sort of irritation he would've felt 356 00:23:05,319 --> 00:23:10,442 when Onnes came in for the dutch to liquify helium 357 00:23:10,443 --> 00:23:14,559 and even today Onnes' discovery of liquid helium 358 00:23:14,659 --> 00:23:17,160 is seen as a much more significant discovery 359 00:23:17,860 --> 00:23:20,559 than Dewar's work on liquifying hydrogen, 360 00:23:20,640 --> 00:23:23,700 which is slightly unfair, 'cause it's all part of the process of 361 00:23:24,001 --> 00:23:25,980 trying to achieve absolute zero. 362 00:23:28,582 --> 00:23:32,862 It remained, that's very clear, a wound 363 00:23:32,963 --> 00:23:36,778 in Dewar's soul that never really healed. 364 00:23:37,380 --> 00:23:40,400 I think that Dewar emerges at the end of the story 365 00:23:40,600 --> 00:23:43,060 as a rather tragic figure, 366 00:23:44,279 --> 00:23:48,539 one of the very greatest late 19th century british scientists 367 00:23:48,540 --> 00:23:51,798 who in the end is frustrated by a failure 368 00:23:51,799 --> 00:23:55,120 which hardly anybody could have expected him to achieve. 369 00:23:59,199 --> 00:24:03,799 James Dewar's dream of reaching absolute zero was over. 370 00:24:04,699 --> 00:24:06,262 He spent the rest of his life 371 00:24:06,263 --> 00:24:08,198 investigating other scientific problems, 372 00:24:08,440 --> 00:24:11,139 such as the physics of soap bubbles. 373 00:24:13,600 --> 00:24:15,347 He'd always been a loner. 374 00:24:15,448 --> 00:24:18,039 Ultimately, his refusal to collaborate 375 00:24:18,335 --> 00:24:21,720 costed him the glory he felt he deserved. 376 00:24:23,620 --> 00:24:25,330 I think it's really impressive 377 00:24:25,331 --> 00:24:28,135 how often scientists do seem to be driven 378 00:24:28,136 --> 00:24:30,159 by the spirit of competition, 379 00:24:30,439 --> 00:24:32,960 by the spirit of getting there first. 380 00:24:33,120 --> 00:24:35,759 But what's really fascinating about these races, 381 00:24:35,880 --> 00:24:37,519 the race for absolute zero, 382 00:24:38,320 --> 00:24:41,880 is that the goalposts move as you're playing the game. 383 00:24:42,760 --> 00:24:46,859 The race in science is not for a predetermined end, 384 00:24:47,239 --> 00:24:49,680 and once you're there, the story's over, 385 00:24:49,759 --> 00:24:50,939 the curtain comes down. 386 00:24:51,039 --> 00:24:52,619 That's not at all what it's like. 387 00:24:52,940 --> 00:24:56,440 Rather, it turns out you find things you didn't expect. 388 00:24:57,200 --> 00:25:00,759 Nature is cunning, as Einstein would have said, 389 00:25:01,080 --> 00:25:06,640 and she is constantly posing a new challenge, 390 00:25:07,120 --> 00:25:10,859 unanticipated by those people who start out on the race. 391 00:25:13,059 --> 00:25:15,267 Sometimes, an unexpected event 392 00:25:15,368 --> 00:25:17,960 triggers a whole new area of research. 393 00:25:18,360 --> 00:25:19,680 This happened in Leiden 394 00:25:19,759 --> 00:25:22,759 as Onnes' team began to investigate how materials 395 00:25:22,839 --> 00:25:26,240 conduct electricity at these very low temperatures. 396 00:25:28,719 --> 00:25:32,799 They observed that at around 4 degrees above absolute zero, 397 00:25:32,899 --> 00:25:37,240 all resistance to the flow of electricity abruptly vanished. 398 00:25:39,000 --> 00:25:42,160 Electrical resistance dropped as if it had gone over a cliff. 399 00:25:42,500 --> 00:25:46,213 It was going down and down and down and then disappeared 400 00:25:46,214 --> 00:25:47,638 or all but disappeared. 401 00:25:48,040 --> 00:25:49,283 Now, this was an astonishing thing. 402 00:25:49,284 --> 00:25:51,478 Nobody ever had seen anything like this before. 403 00:25:51,480 --> 00:25:55,480 There was nothing on Earth that had no electrical resistance. 404 00:25:56,279 --> 00:26:01,120 Onnes later invented a new word to describe this bizarre phenomenon. 405 00:26:01,519 --> 00:26:04,200 He called it "superconductivity." 406 00:26:12,279 --> 00:26:15,680 (Allan Griffin) We have a circular ring of permanent magnets, 407 00:26:15,859 --> 00:26:17,440 which are producing a magnetic field. 408 00:26:17,880 --> 00:26:21,759 And now when we put a superconducting puck over it 409 00:26:21,880 --> 00:26:22,960 and give it a little push, 410 00:26:23,960 --> 00:26:27,240 the magnetic field repels the superconductor. 411 00:26:30,039 --> 00:26:31,759 The magnetic field from the track 412 00:26:31,880 --> 00:26:34,360 induces a current in the supercooled puck, 413 00:26:34,519 --> 00:26:37,440 which in turn creates an opposite magnetic field 414 00:26:37,519 --> 00:26:39,360 that makes the puck levitate. 415 00:26:41,360 --> 00:26:43,279 It produces a magnetic field 416 00:26:43,360 --> 00:26:45,119 like a north pole against north pole, 417 00:26:45,120 --> 00:26:46,519 and that's why you have the repulsion. 418 00:26:47,839 --> 00:26:49,120 As the puck warms up, 419 00:26:49,200 --> 00:26:51,440 its superconducting properties vanish 420 00:26:51,519 --> 00:26:53,960 along with its magnetically induced field. 421 00:26:55,600 --> 00:26:58,460 For decades after its discovery in 1911, 422 00:26:58,540 --> 00:27:01,080 the underlying cause of superconductivity 423 00:27:01,260 --> 00:27:02,880 remained a mystery. 424 00:27:03,600 --> 00:27:07,239 Every major physicist, every major theoretical physicist 425 00:27:07,420 --> 00:27:09,279 had his own theory of superconductivity. 426 00:27:09,360 --> 00:27:12,640 Everybody tried to solve it, but it was unsuccessful. 427 00:27:15,839 --> 00:27:17,640 There were more surprises ahead. 428 00:27:18,039 --> 00:27:20,519 In the 1930s, another strange phenomenon 429 00:27:20,600 --> 00:27:22,980 was observed at even lower temperatures. 430 00:27:24,039 --> 00:27:27,360 This rapidly evaporating liquid helium cools 431 00:27:27,440 --> 00:27:30,279 until at 2 degrees above absolute zero, 432 00:27:30,360 --> 00:27:32,880 a dramatic transformation takes place. 433 00:27:35,880 --> 00:27:38,960 (Allan Griffin) Suddenly you see that the bubbling stops 434 00:27:39,160 --> 00:27:40,880 and that the surface of the liquid helium 435 00:27:41,060 --> 00:27:42,780 is completely still. 436 00:27:43,279 --> 00:27:44,580 The temperature is actually being lowered 437 00:27:44,659 --> 00:27:47,200 even further now, but nothing particularly is happening. 438 00:27:47,279 --> 00:27:49,980 Well, this is really one of the great phenomenon 439 00:27:50,059 --> 00:27:52,039 in 20th-century physics. 440 00:27:54,259 --> 00:27:57,200 The liquid helium had turned into a superfluid, 441 00:27:57,479 --> 00:27:59,960 which displays some really odd properties. 442 00:28:00,839 --> 00:28:02,080 Here I have a beaker 443 00:28:02,279 --> 00:28:05,880 with an unglazed ceramic bottom of ultrafine porosity. 444 00:28:07,600 --> 00:28:08,960 Ordinarily, this container 445 00:28:09,039 --> 00:28:11,680 with tiny pores can hold liquid helium, 446 00:28:13,200 --> 00:28:17,120 but the moment the helium turns superfluid, it leaks through. 447 00:28:18,520 --> 00:28:21,660 We call this kind of flow a "superflow." 448 00:28:24,220 --> 00:28:26,539 Superfluid helium can do things 449 00:28:26,540 --> 00:28:28,360 we might have believed impossible. 450 00:28:28,939 --> 00:28:30,959 It appears to defy gravity. 451 00:28:31,640 --> 00:28:34,839 A thin film can climb walls and escape its container. 452 00:28:35,519 --> 00:28:39,320 This is because a superfluid has zero viscosity. 453 00:28:40,519 --> 00:28:43,600 It can even produce a frictionless fountain, 454 00:28:44,039 --> 00:28:45,839 one that never stops flowing. 455 00:28:47,360 --> 00:28:49,679 Superfluidity and superconductivity 456 00:28:49,680 --> 00:28:51,880 were baffling concepts for scientists. 457 00:28:52,560 --> 00:28:55,680 New radical theories were needed to explain them. 458 00:29:01,600 --> 00:29:05,279 In the 1920s, quantum theory was emerging as the best hope 459 00:29:05,360 --> 00:29:07,519 of understanding these strange phenomena. 460 00:29:08,600 --> 00:29:10,680 Its central idea was that atoms 461 00:29:10,759 --> 00:29:13,519 do not always behave like individual particles. 462 00:29:14,040 --> 00:29:17,759 Sometimes they merge together and behave like waves. 463 00:29:21,759 --> 00:29:25,200 They can even be particles and waves at the same time. 464 00:29:26,699 --> 00:29:29,519 This strange paradox was hard to accept, 465 00:29:29,680 --> 00:29:32,519 even for great minds like Albert Einstein. 466 00:29:34,440 --> 00:29:39,360 In 1925, a young Indian physicist, Satyendra Bose, 467 00:29:39,440 --> 00:29:42,600 sent Einstein a paper he'd been unable to publish. 468 00:29:42,980 --> 00:29:44,879 Bose had attempted to apply 469 00:29:44,880 --> 00:29:49,279 the mathematics of how light particles behave to whole atoms. 470 00:29:53,039 --> 00:29:55,719 Einstein realized the importance of this concept 471 00:29:55,960 --> 00:29:57,960 and did some further calculations. 472 00:29:58,519 --> 00:30:01,880 He predicted that on reaching extremely low temperatures, 473 00:30:01,959 --> 00:30:05,719 just a hair above absolute zero, it might be possible 474 00:30:05,720 --> 00:30:09,880 to produce a new state of matter that followed quantum rules. 475 00:30:12,680 --> 00:30:16,120 It would not be a solid or liquid or gas. 476 00:30:16,600 --> 00:30:20,240 It was given a name almost as strange as its properties: 477 00:30:20,680 --> 00:30:23,519 a Bose-Einstein condensate. 478 00:30:26,839 --> 00:30:28,120 For the next 70 years, 479 00:30:28,200 --> 00:30:31,759 people could only dream about making such a condensate, 480 00:30:34,120 --> 00:30:36,200 Matter can exist in various states. 481 00:30:36,879 --> 00:30:39,360 Atoms at high temperature always form gases. 482 00:30:39,740 --> 00:30:42,039 If you cool the gas, it becomes a liquid. 483 00:30:42,120 --> 00:30:44,139 If you cool the liquid, it becomes a solid. 484 00:30:44,960 --> 00:30:46,600 But under certain circumstances, 485 00:30:46,680 --> 00:30:50,039 if you cool atoms far enough to extremely low temperatures, 486 00:30:50,519 --> 00:30:53,120 they undergo a very strange transformation, 487 00:30:53,759 --> 00:30:55,880 they undergo an identity crisis. 488 00:30:56,680 --> 00:30:58,880 So let me show you what I mean by "an identity crisis." 489 00:30:59,960 --> 00:31:01,839 When you go to low temperatures, the 490 00:31:01,880 --> 00:31:04,460 quantum mechanical properties of the atoms become important. 491 00:31:05,360 --> 00:31:08,279 These are very strange, very unfamiliar to us, 492 00:31:08,440 --> 00:31:10,360 but in fact, each one of these atoms 493 00:31:10,440 --> 00:31:12,859 starts to display wavelike properties. 494 00:31:13,279 --> 00:31:15,519 So instead of points like that, 495 00:31:15,600 --> 00:31:19,120 you have little wave packets, like that, moving around. 496 00:31:21,440 --> 00:31:24,120 It's really difficult for me to explain just why that is, 497 00:31:24,200 --> 00:31:25,400 but that's the way it is. 498 00:31:25,680 --> 00:31:27,759 Now, as you go to very low temperatures, 499 00:31:27,880 --> 00:31:32,759 the size of these packets gets longer and longer and longer. 500 00:31:33,279 --> 00:31:36,600 And then suddenly, if you get them cold enough, 501 00:31:37,440 --> 00:31:39,839 they start overlapping, and when they overlap, 502 00:31:40,200 --> 00:31:43,960 the system behaves not like individual particles, 503 00:31:44,519 --> 00:31:46,600 but particles which have lost their identity. 504 00:31:46,960 --> 00:31:48,420 They all think they're everywhere. 505 00:31:49,600 --> 00:31:52,300 This little wave packet over here can't tell 506 00:31:52,360 --> 00:31:54,680 whether it's this one or that one or that one. 507 00:31:54,860 --> 00:31:56,480 Or that one or that one or that one. 508 00:31:56,720 --> 00:31:58,160 It's there, and it's there, and it's there. 509 00:31:59,039 --> 00:32:01,479 They're all in one great big quantum state, 510 00:32:01,500 --> 00:32:02,759 they're all overlapping. 511 00:32:03,039 --> 00:32:04,800 They're all doing the same thing, 512 00:32:05,400 --> 00:32:07,880 and what they're doing, to a good approximation is, 513 00:32:07,960 --> 00:32:09,479 they're simply sitting at rest. 514 00:32:10,360 --> 00:32:11,880 This Bose-Einstein condensate is 515 00:32:11,960 --> 00:32:14,479 very difficult to imagine or to visualize. 516 00:32:14,680 --> 00:32:16,440 I could imagine what it's like to be an atom 517 00:32:16,519 --> 00:32:19,600 running around gaily, freely, bouncing into things, 518 00:32:19,680 --> 00:32:21,839 sometimes going fast, sometimes going slow, 519 00:32:22,680 --> 00:32:26,200 but in the Bose condensate, I'm everywhere at once. 520 00:32:26,500 --> 00:32:29,160 I've lost my identity. I don't know who I am anymore. 521 00:32:29,960 --> 00:32:33,960 I'm at rest, and all the other atoms around are at rest. 522 00:32:34,039 --> 00:32:35,500 But there are not other atoms around. 523 00:32:35,580 --> 00:32:37,440 We're all just one great big quantum system. 524 00:32:37,960 --> 00:32:40,060 There's nothing else like that in physics 525 00:32:40,320 --> 00:32:42,360 and certainly not in human experience. 526 00:32:42,839 --> 00:32:47,279 So just to think about this causes me wonder and confusion. 527 00:32:52,680 --> 00:32:55,118 Dan Kleppner's group, at MIT, began 528 00:32:55,119 --> 00:32:58,680 to try to make a Bose-Einstein condensate in hydrogen. 529 00:33:10,680 --> 00:33:13,600 (Dan Kleppner) As we started out the search for Bose-Einstein condensation, 530 00:33:13,680 --> 00:33:17,039 our enthusiasm grew because hydrogen seemed 531 00:33:17,200 --> 00:33:20,519 like such a wonderful atom to use. 532 00:33:20,600 --> 00:33:21,880 It had everything going for it. 533 00:33:22,040 --> 00:33:23,279 It had its light mass. 534 00:33:23,980 --> 00:33:26,759 That means that the atoms will condense 535 00:33:26,880 --> 00:33:29,120 at a higher temperature than other atoms would. 536 00:33:29,300 --> 00:33:31,700 The atoms interact with each other very, very weakly. 537 00:33:32,200 --> 00:33:34,220 All the signals seem to be pointing to the fact 538 00:33:34,519 --> 00:33:36,439 that hydrogen was the atom 539 00:33:36,440 --> 00:33:38,440 for getting to Bose-Einstein condensation. 540 00:33:40,200 --> 00:33:43,239 Dan Kleppner's idea was to cool the hydrogen atoms 541 00:33:43,240 --> 00:33:45,519 by making use of their magnetic poles. 542 00:33:46,060 --> 00:33:48,139 He used a strong magnetic field 543 00:33:48,360 --> 00:33:51,479 to create a cluster of atoms in a cold trap. 544 00:33:51,880 --> 00:33:54,939 Unfortunately, sometimes one atom flipped another, 545 00:33:55,080 --> 00:33:58,400 which triggered a release of energy that raised the temperature. 546 00:34:02,600 --> 00:34:04,279 It was a frustrating time for us 547 00:34:04,560 --> 00:34:06,780 because our methods were so complicated 548 00:34:07,400 --> 00:34:09,599 we were having a hard time moving forwards. 549 00:34:14,620 --> 00:34:17,079 It was time for the next generation to have a go. 550 00:34:17,539 --> 00:34:20,279 Two scientists who trained in Kleppner's department 551 00:34:20,280 --> 00:34:22,920 moved down west to Boulder, Colorado. 552 00:34:23,320 --> 00:34:25,960 They came up with a different approach to the problem. 553 00:34:26,360 --> 00:34:27,559 Rather than focusing on 554 00:34:27,560 --> 00:34:30,000 the lighter atoms of the periodic table, 555 00:34:30,080 --> 00:34:33,959 Eric Cornell and Carl Weiman hit upon the idea of using 556 00:34:33,960 --> 00:34:37,399 much heavier metallic atoms, like rubidium and caesium. 557 00:34:38,399 --> 00:34:40,778 But would using these giants enable them 558 00:34:40,779 --> 00:34:43,560 to reach closer to absolute zero? 559 00:34:44,900 --> 00:34:47,439 The idea in the field in those days was that 560 00:34:47,519 --> 00:34:49,639 the light things like hydrogen and lithium would be easier, 561 00:34:49,640 --> 00:34:51,640 and there are some good reasons for thinking that. 562 00:34:51,900 --> 00:34:53,080 But we had other ideas. 563 00:34:53,160 --> 00:34:57,000 Yeah, sort of gut intuition in some sense. 564 00:34:59,239 --> 00:35:02,360 Their plan was to use a laser beam to cool the atoms, 565 00:35:02,720 --> 00:35:07,000 a technique that had already been tried by their old lab at MIT. 566 00:35:08,300 --> 00:35:11,660 Lasers are usually associated with making things hot, 567 00:35:11,760 --> 00:35:14,639 but if they are tuned to the same frequency as atoms 568 00:35:14,640 --> 00:35:18,360 traveling at a particular speed, they can make them cold. 569 00:35:23,959 --> 00:35:26,639 When the stream of light particles from the laser 570 00:35:26,640 --> 00:35:29,079 hits the selected atoms in the gas cloud, 571 00:35:29,560 --> 00:35:33,280 the atoms slow down and hence become cold. 572 00:35:37,399 --> 00:35:40,399 Laser cooling was a new tool that had the potential 573 00:35:40,480 --> 00:35:42,319 to reduce the temperature of a gas 574 00:35:42,799 --> 00:35:47,000 to within a few millionths of a degree of absolute zero. 575 00:35:52,239 --> 00:35:53,678 But Cornell and Weiman were not 576 00:35:53,679 --> 00:35:56,360 the only ones excited by this prospect. 577 00:35:56,460 --> 00:35:59,239 A new scientist had arrived at MIT. 578 00:36:03,080 --> 00:36:07,319 (Wolfgang Ketterle) It was in late '91 or early '92 that we had an idea, 579 00:36:07,640 --> 00:36:11,099 an idea how a different arrangement of laser beams 580 00:36:11,399 --> 00:36:14,079 would be able to cool atoms to higher density. 581 00:36:14,520 --> 00:36:15,560 And it worked! 582 00:36:18,000 --> 00:36:19,999 And this was really a trigger point. 583 00:36:20,640 --> 00:36:23,480 I will never forget the excitement in those groups, 584 00:36:23,520 --> 00:36:26,099 group meetings, when we discussed What do we next? 585 00:36:26,239 --> 00:36:27,760 Because with higher density 586 00:36:27,799 --> 00:36:29,000 there are many things you can do. 587 00:36:30,039 --> 00:36:32,879 Could we now push to Bose-Einstein condensation? 588 00:36:34,020 --> 00:36:37,019 I see, well, lots of cables and electronics... 589 00:36:37,319 --> 00:36:40,067 Ketterle used used the full might of MIT's founding 590 00:36:40,068 --> 00:36:41,518 to build a laser lab 591 00:36:41,519 --> 00:36:44,560 to try to make a condensate in sodium atoms. 592 00:36:44,940 --> 00:36:46,399 This is an atomic beam oven. 593 00:36:46,740 --> 00:36:49,999 What is wrapped in tinfoil is a little vacuum chamber 594 00:36:50,080 --> 00:36:52,300 where we heat up metallic sodium, 595 00:36:52,419 --> 00:36:55,099 so the metallic sodium melts and evaporates, 596 00:36:55,460 --> 00:36:57,740 and it's ultimately the sodium vapor, 597 00:36:57,759 --> 00:37:01,760 the sodium atoms, which we tried to Bose-Einstein condense. 598 00:37:08,499 --> 00:37:12,999 MIT, Boulder, and several other labs were chasing the same goal. 599 00:37:14,319 --> 00:37:15,778 It had echoes of the race 600 00:37:15,779 --> 00:37:19,000 to produce liquid helium almost a century earlier. 601 00:37:21,139 --> 00:37:23,079 (Eric Cornell) As I tell my students today, 602 00:37:23,139 --> 00:37:25,280 anything worth doing is worth doing quickly, 603 00:37:25,560 --> 00:37:27,879 because science moves on and 604 00:37:30,160 --> 00:37:33,699 we're all mortal and you want to do things. 605 00:37:34,799 --> 00:37:38,479 While MIT was installing expensive industrial lasers, 606 00:37:38,679 --> 00:37:41,000 Carl Weiman had a different approach. 607 00:37:41,600 --> 00:37:44,559 I, throughout my experimental physics career, 608 00:37:44,560 --> 00:37:46,398 always felt that 609 00:37:47,200 --> 00:37:49,150 technology played the big part, 610 00:37:49,151 --> 00:37:52,519 so if you could figure out a better technology for doing something 611 00:37:52,619 --> 00:37:55,720 it was gonna pay off in the long run, in physics. 612 00:37:56,839 --> 00:38:00,080 (Eric Cornell) In some cases, he was ripping open old fax machines 613 00:38:00,160 --> 00:38:01,619 and taking out the little chip inside 614 00:38:01,620 --> 00:38:04,160 that made the laser and showed that you could take these lasers 615 00:38:04,239 --> 00:38:08,160 and put them into a home-built piece of apparatus, 616 00:38:08,800 --> 00:38:09,691 stabilize the laser 617 00:38:09,692 --> 00:38:11,820 and use them to do spectroscopy and laser cooling. 618 00:38:13,160 --> 00:38:15,419 (Carl Weiman) This is actually our first, 619 00:38:16,080 --> 00:38:19,339 what's called a "vapor cell optical trap." 620 00:38:19,959 --> 00:38:22,319 You can see it's kind of this old cruddy thing 621 00:38:22,399 --> 00:38:25,640 pulled together glass where we could send laser beams in 622 00:38:25,720 --> 00:38:27,239 from all the different directions 623 00:38:27,319 --> 00:38:30,080 and have just a little bit of the atoms we wanted to cool. 624 00:38:33,560 --> 00:38:36,239 As well as bombarding the atoms with lasers, 625 00:38:36,419 --> 00:38:39,780 they also trapped them in a strong magnetic field. 626 00:38:42,080 --> 00:38:44,620 You can have all your magnetic trap coils 627 00:38:44,621 --> 00:38:46,517 outside of the vacuum system 628 00:38:47,880 --> 00:38:51,519 and then again, it's a lot easier, simpler, to do everything. 629 00:38:52,720 --> 00:38:54,479 We would try this sort of magnetic trap, 630 00:38:54,480 --> 00:38:56,959 that sort of magnetic trap, this sort of imaging, 631 00:38:57,000 --> 00:38:58,899 that sort of imaging, that sort of cooling. 632 00:38:59,179 --> 00:39:00,360 All those things we could do 633 00:39:00,440 --> 00:39:02,639 without building a whole new chamber each time. 634 00:39:02,640 --> 00:39:07,000 We tried literally 4 different magnetic traps in 4 years 635 00:39:07,071 --> 00:39:10,040 instead of having a 3 or 4-year construction project for each one. 636 00:39:11,700 --> 00:39:13,720 By being fast and flexible, 637 00:39:13,799 --> 00:39:16,899 the Boulder group hoped to beat their old lab at MIT, 638 00:39:17,379 --> 00:39:19,840 but MIT had its own plans. 639 00:39:20,040 --> 00:39:22,599 This was a prize they felt should be theirs. 640 00:39:24,160 --> 00:39:25,839 (Wolfgang Ketterle) There was a sense of competition, 641 00:39:25,840 --> 00:39:28,720 but it was what I would call friendly competition. 642 00:39:29,080 --> 00:39:30,799 I mean, can you imagine 2 athletes? 643 00:39:31,160 --> 00:39:32,639 They are in the same training camps, 644 00:39:32,640 --> 00:39:35,879 they help each other, they even give tips to each other, 645 00:39:36,079 --> 00:39:38,318 but then when it comes to the race, 646 00:39:38,319 --> 00:39:40,159 everybody wants to be the first. 647 00:39:44,080 --> 00:39:45,778 The rival groups were all using 648 00:39:45,779 --> 00:39:48,999 magnetic trapping and laser cooling to cool their atoms, 649 00:39:49,599 --> 00:39:52,280 but for the final push towards absolute zero 650 00:39:52,339 --> 00:39:53,740 to turn these atoms of gas 651 00:39:53,820 --> 00:39:57,000 into the quantum state Einstein had predicted, 652 00:39:57,080 --> 00:40:01,480 they needed one more cooling technique: evaporative cooling. 653 00:40:02,640 --> 00:40:05,799 It's just like with this coffee; the steam coming off of the coffee 654 00:40:06,180 --> 00:40:07,959 is the hottest of the coffee molecules 655 00:40:08,000 --> 00:40:10,560 escaping and carrying away more than their fair share of energy. 656 00:40:10,959 --> 00:40:13,319 In the case of the atoms, we keep the atoms in 657 00:40:13,399 --> 00:40:18,239 a sort of magnetic bowl, and we confine the atoms there, 658 00:40:18,319 --> 00:40:20,399 they zoom around inside the bowl, and then the hottest ones 659 00:40:20,480 --> 00:40:22,799 have enough energy to roll up the side of the bowl 660 00:40:22,879 --> 00:40:24,480 and fall over the edge, slop over the edge, 661 00:40:24,560 --> 00:40:27,640 taking away with them much more than their fair share of energy. 662 00:40:27,720 --> 00:40:30,000 And the atoms that remain have less and less energy, 663 00:40:30,080 --> 00:40:31,560 which means they move slower and slower 664 00:40:31,640 --> 00:40:33,439 and start to cluster near the bottom. 665 00:40:35,420 --> 00:40:36,239 And as that happens, 666 00:40:36,319 --> 00:40:38,799 we gradually lower the edges of the magnetic trap 667 00:40:39,640 --> 00:40:41,879 and always so there's just a few atoms that can escape, 668 00:40:42,000 --> 00:40:44,560 until finally the remaining atoms cluster 669 00:40:44,640 --> 00:40:46,319 near the bottle of the bowl, huddle together, 670 00:40:46,599 --> 00:40:48,799 they get colder and colder and denser and denser 671 00:40:48,979 --> 00:40:51,000 and eventually in this way, evaporation forces 672 00:40:51,080 --> 00:40:53,580 the Bose-Einstein condensation to occur. 673 00:40:58,399 --> 00:41:00,806 One problem that we kept encountering 674 00:41:00,807 --> 00:41:03,879 is that we had to keep the atoms isolated from the walls. 675 00:41:03,900 --> 00:41:05,513 We had got a really good vacuum 676 00:41:05,514 --> 00:41:07,418 and yet if the vacuum is perfect, 677 00:41:07,619 --> 00:41:09,340 what is that you're actually working with, 678 00:41:09,341 --> 00:41:11,505 we had had a little bit of rubidium gas in there, 679 00:41:11,506 --> 00:41:13,819 a tiny bit rubidium gas that we could capture, 680 00:41:13,820 --> 00:41:15,835 catch with our lasers and slow down. 681 00:41:15,840 --> 00:41:18,420 So we had this wild idea of changing... 682 00:41:18,821 --> 00:41:22,360 constantly changing the pressure in the chamber, 683 00:41:22,560 --> 00:41:24,180 letting the pressure get higher and lower, 684 00:41:24,240 --> 00:41:25,878 and we built a very elaborated chamber 685 00:41:25,879 --> 00:41:31,040 with valves that open and close and a pump to turn on and off 686 00:41:31,360 --> 00:41:33,980 and it didn't work for beams, I mean 687 00:41:34,080 --> 00:41:36,954 we spent six months wasted, I might say six months on 688 00:41:37,155 --> 00:41:39,379 valves opening, closing, pumps turning on and off. 689 00:41:39,479 --> 00:41:42,355 The problem is the rubidium gas had a little bit of stickyness to it 690 00:41:42,356 --> 00:41:44,157 and that meant when we were trying to *sucking sound* 691 00:41:44,280 --> 00:41:45,499 get all the rubidium out of there, 692 00:41:45,580 --> 00:41:48,000 that residual gas was heating up the atoms. 693 00:41:50,319 --> 00:41:53,479 So eventually we had to give up on that idea. 694 00:41:57,139 --> 00:41:58,319 By now the race to produce 695 00:41:58,399 --> 00:42:01,480 a Bose-Einstein condensate was intensifying. 696 00:42:02,720 --> 00:42:04,239 At every major meeting, 697 00:42:04,959 --> 00:42:07,740 Eric Cornell and I gave talks or talked to each other. 698 00:42:08,080 --> 00:42:10,479 We were keenly aware that we were 699 00:42:10,480 --> 00:42:12,280 both working towards the same goal. 700 00:42:14,379 --> 00:42:17,224 It's a mixed thing. On the one hand it's flattering 701 00:42:17,225 --> 00:42:19,566 because they're using an approach which we had pioneered, 702 00:42:19,567 --> 00:42:20,775 that we felt good about that. 703 00:42:20,980 --> 00:42:22,978 On the other hand there was... maybe we were still little nervous 704 00:42:22,979 --> 00:42:25,864 because... hmm... we want to advance knowledge, 705 00:42:26,065 --> 00:42:28,172 but science is a competitive business. 706 00:42:28,173 --> 00:42:30,274 and we felt that we wanted to do it first and... 707 00:42:30,380 --> 00:42:32,279 and maybe that we were entitled to do it first. 708 00:42:32,380 --> 00:42:33,378 Although even that's a mixed bag 709 00:42:33,380 --> 00:42:36,179 because after all we had jumped into the game of the hydrogen people 710 00:42:36,180 --> 00:42:38,480 who had shown us so many of the tricks over the years. 711 00:42:39,180 --> 00:42:42,756 At one point, during that period I remember Carl Weiman 712 00:42:42,757 --> 00:42:45,220 being quoted at an article saying that 713 00:42:45,300 --> 00:42:47,667 he hopes that the MIT group gets there first 714 00:42:47,668 --> 00:42:50,517 'cause they started there it all and so they'll get the Nobel Prize 715 00:42:50,519 --> 00:42:54,640 and then the, the other group will do the interesting science. 716 00:42:54,840 --> 00:42:57,079 Well, that was a very nice thought. 717 00:42:57,480 --> 00:42:58,820 Didn't quite work out that way. 718 00:43:00,720 --> 00:43:04,720 In June 1995, the Boulder group was working 'round the clock 719 00:43:04,799 --> 00:43:06,319 knowing that several other labs 720 00:43:06,399 --> 00:43:09,399 were also poised to produce the first condensate. 721 00:43:09,879 --> 00:43:12,880 An official visit from a government-funding committee 722 00:43:13,060 --> 00:43:14,840 was the last thing they needed. 723 00:43:16,720 --> 00:43:18,849 The standard thing you do when important people come around 724 00:43:18,850 --> 00:43:20,879 is you close down your lab and clean up everything 725 00:43:20,959 --> 00:43:24,319 and put posters on the walls so they can see how productive you are. 726 00:43:24,399 --> 00:43:26,919 Of course, that's the exact opposite of being productive. 727 00:43:26,920 --> 00:43:28,480 We didn't want to close down the lab 728 00:43:28,560 --> 00:43:30,318 or clean up our lab or put up posters. 729 00:43:30,319 --> 00:43:31,399 We wanted to work very hard. 730 00:43:31,480 --> 00:43:34,799 So the senior dignitaries in the 3-piece suits and so on 731 00:43:34,879 --> 00:43:37,720 came in to the lab, and we left the lights off, 732 00:43:37,799 --> 00:43:39,640 and everyone continued to work, 733 00:43:39,720 --> 00:43:41,560 and I made them keep their voices down. 734 00:43:41,840 --> 00:43:44,720 And talked to them rather in a hurried way 735 00:43:44,799 --> 00:43:46,160 and then sort of shuffled them out the door, 736 00:43:46,239 --> 00:43:48,799 and they all had a slightly puzzled look on their face 737 00:43:48,959 --> 00:43:50,799 'cause it probably had never happened to them before 738 00:43:50,879 --> 00:43:52,640 in their history of being a visiting committee, 739 00:43:52,720 --> 00:43:56,879 that they were treated with as little... little pomp. 740 00:43:57,560 --> 00:44:00,160 And later, I actually met one of the guys who said, 741 00:44:00,339 --> 00:44:02,399 "I suspected something was up that day 742 00:44:02,480 --> 00:44:04,399 because otherwise you never would've dared to do that". 743 00:44:06,319 --> 00:44:08,339 June the 5th, 1995 744 00:44:08,419 --> 00:44:11,080 turned out to be a big day in the history of physics. 745 00:44:11,480 --> 00:44:16,159 They had finally made what Einstein had predicted 70 years before: 746 00:44:16,399 --> 00:44:19,519 a Bose-Einstein condensate. 747 00:44:19,640 --> 00:44:23,160 Our first reaction was wait, we gotta be careful here, you know. 748 00:44:23,239 --> 00:44:26,560 Let's think of all the different knobs we can turn, 749 00:44:26,640 --> 00:44:28,560 checks we can make and so on 750 00:44:28,640 --> 00:44:33,879 to see if this really is Bose-Einstein condensation. 751 00:44:47,480 --> 00:44:49,000 The condensate is sort of like a vampire. 752 00:44:49,080 --> 00:44:51,160 If the sunlight even once falls on it, it's dead, 753 00:44:51,879 --> 00:44:54,480 and so it... its realm is the realm of the dark. 754 00:44:54,799 --> 00:44:56,079 But we can take pictures of them 755 00:44:56,080 --> 00:44:57,959 because we strobe the laser light really fast, 756 00:44:58,080 --> 00:45:01,160 and even as the condensate's dying, it casts a shadow, 757 00:45:01,239 --> 00:45:04,160 and the shadow is frozen in the film. 758 00:45:04,840 --> 00:45:09,257 Weiman and Cornell created the first Bose-Einstein condensate 759 00:45:09,258 --> 00:45:11,720 in a cloud of just 3000 atoms of rubidium, 760 00:45:12,079 --> 00:45:15,799 the first in the universe, as far as we know. 761 00:45:16,399 --> 00:45:17,640 They had reached the temperature of 762 00:45:17,699 --> 00:45:22,517 170 billionths of a degree above absolute zero. 763 00:45:24,420 --> 00:45:25,560 One of the first things you need to understand 764 00:45:25,640 --> 00:45:28,840 about Bose-Einstein condensation is how very, very cold it is. 765 00:45:29,799 --> 00:45:31,360 Where we live, at room temperature, 766 00:45:32,399 --> 00:45:34,619 is far above absolute zero in the scale. 767 00:45:36,079 --> 00:45:38,999 Imagine that room temperature is represented by London, 768 00:45:39,160 --> 00:45:40,560 thousands of kilometers from here. 769 00:45:41,040 --> 00:45:43,480 Then on that scale, if we imagine right here 770 00:45:43,560 --> 00:45:45,979 where I'm standing in Boulder is absolute zero, 771 00:45:46,060 --> 00:45:47,480 the coldest possible temperature, 772 00:45:47,660 --> 00:45:49,920 then how close are we to absolute zero? 773 00:45:50,660 --> 00:45:52,239 If we think of London as being room temperature 774 00:45:52,319 --> 00:45:54,160 and right where I am is absolute zero, then 775 00:45:55,239 --> 00:45:57,859 Bose-Einstein condensation occurs 776 00:45:57,860 --> 00:46:01,439 just the thickness of this pencil lead away from absolute zero. 777 00:46:06,480 --> 00:46:08,799 Within weeks of the Boulder group's success, 778 00:46:09,160 --> 00:46:12,279 Wolfgang Ketterle produced an even larger condensate 779 00:46:12,280 --> 00:46:14,679 from ten million sodium atoms. 780 00:46:17,319 --> 00:46:18,879 At last, quantum mechanics 781 00:46:19,000 --> 00:46:22,079 was more than just theoretical mambo-jumbo. 782 00:46:22,760 --> 00:46:26,080 It was something that could be seen with the naked eye. 783 00:46:32,000 --> 00:46:33,399 Weiman, Cornell & Ketterle 784 00:46:33,480 --> 00:46:36,879 shared the Nobel Prize for physics in 2001. 785 00:46:38,959 --> 00:46:40,519 (Carl Weiman) One of the things Nobel Prize 786 00:46:40,959 --> 00:46:43,439 means and the ceremony means is 787 00:46:43,440 --> 00:46:45,560 that everybody remembers Eric's the person 788 00:46:45,720 --> 00:46:47,360 who forgot to bow to the king! 789 00:46:48,920 --> 00:46:51,720 There was a breakdown of protocol on my part. 790 00:46:53,239 --> 00:46:55,360 There was no excuse because they actually drill us. 791 00:46:55,660 --> 00:46:57,080 It's more like a... we have a series of rehearsals 792 00:46:57,339 --> 00:47:00,399 practicing how to bow to the king, and I somehow managed 793 00:47:00,560 --> 00:47:02,799 to bollocks it up at the last possible moment. 794 00:47:08,419 --> 00:47:09,878 And I thought maybe, you know, 795 00:47:09,879 --> 00:47:12,740 Carl who came after me would do this, make the same mistake, 796 00:47:12,799 --> 00:47:14,280 and then no one would figure it out, 797 00:47:14,430 --> 00:47:15,578 but no, he was perfect. 798 00:47:22,640 --> 00:47:24,399 (Wolfgang Ketterle) I heard about the Nobel Prize when I was 799 00:47:24,879 --> 00:47:26,399 woken up by a telephone call, 800 00:47:26,480 --> 00:47:28,560 which was at, I think, 5:30 in the morning. 801 00:47:29,300 --> 00:47:31,080 So you wake up, you go to the telephone, 802 00:47:31,160 --> 00:47:32,497 and somebody tells you, 803 00:47:32,498 --> 00:47:34,560 "Congratulations, you have won the Nobel Prize." 804 00:47:35,560 --> 00:47:38,239 You're still tired, your brain is not fully functional, 805 00:47:38,319 --> 00:47:40,399 but you realize this is big and... 806 00:47:41,499 --> 00:47:45,000 and what you feel is, you know, pride, 807 00:47:45,080 --> 00:47:49,000 pride for MIT, your collaborators, for yourself. 808 00:47:50,000 --> 00:47:53,238 It's wonderful to see that your work gets recognized 809 00:47:53,239 --> 00:47:54,680 and acknowledged in this way. 810 00:47:58,959 --> 00:48:00,900 Like any great adventure, 811 00:48:00,980 --> 00:48:03,779 the pursuit of science offers no guarantee of success. 812 00:48:04,640 --> 00:48:07,280 But for the godfather of ultra cold atoms, 813 00:48:07,760 --> 00:48:10,239 persistence eventually paid off. 814 00:48:11,720 --> 00:48:15,319 After 20 years of struggling to obtain a condensate in hydrogen, 815 00:48:15,720 --> 00:48:18,640 Dan Kleppner finally succeeded. 816 00:48:20,720 --> 00:48:25,000 For a few fleeting moments, his dream came true. 817 00:48:25,960 --> 00:48:27,000 (Daniel Kleppner) Of course, we were delighted, 818 00:48:27,319 --> 00:48:28,480 and I think everyone was delighted 819 00:48:29,000 --> 00:48:30,720 because we'd been working on it for so long. 820 00:48:30,799 --> 00:48:32,560 It's kind of embarrassing to have this group, 821 00:48:32,640 --> 00:48:35,160 which helped start the work and was working away there, 822 00:48:35,560 --> 00:48:38,080 fruitlessly, while everyone was enjoying success. 823 00:48:38,399 --> 00:48:41,480 When we got it, everyone was happy. 824 00:48:44,160 --> 00:48:48,339 (Wolfgang Ketterle) To see that an effort, which lasted for 20 years, 825 00:48:48,560 --> 00:48:52,339 which took so much patience, frustration and tenacity, 826 00:48:52,560 --> 00:48:57,360 to see that succeed is just emotional. It's liberating. 827 00:48:58,239 --> 00:49:01,079 I will never forget the standing ovation, 828 00:49:01,239 --> 00:49:04,280 which Dan Kleppner received at the Verena Summer School 829 00:49:04,380 --> 00:49:07,679 when he announced Bose-Einstein condensation in hydrogen. 830 00:49:08,360 --> 00:49:10,180 Everybody just got up and gave... 831 00:49:10,260 --> 00:49:12,720 it was sort of like an opera, where everybody just cheered, 832 00:49:12,799 --> 00:49:14,807 and people were crying, and... 833 00:49:15,008 --> 00:49:16,714 because everybody realized 834 00:49:16,715 --> 00:49:20,177 that they had finished the race, but too late, 835 00:49:20,959 --> 00:49:22,679 and it wasn't gonna work out, 836 00:49:22,779 --> 00:49:25,759 but in some sense they had really stimulated the whole field. 837 00:49:25,760 --> 00:49:28,560 So it was a very, very moving, very moving moment. 838 00:49:31,720 --> 00:49:34,759 For the pioneers who had realized Einstein's dream 839 00:49:34,760 --> 00:49:36,560 and created condensates, it was 840 00:49:36,720 --> 00:49:39,640 the end of an extraordinary decade of physics. 841 00:49:40,160 --> 00:49:41,480 Now, there was a new challenge: 842 00:49:42,319 --> 00:49:43,959 to work out what to do with them. 843 00:49:49,879 --> 00:49:53,080 At Harvard, a Danish scientist, Lene Hau, 844 00:49:53,160 --> 00:49:56,480 had the idea of using a condensate to slow down light. 845 00:50:00,720 --> 00:50:03,560 We all have this sense, you know, light is something that... 846 00:50:04,560 --> 00:50:08,239 nothing goes faster than light, in vacuum, 847 00:50:08,720 --> 00:50:11,319 and if somehow we could use this system 848 00:50:11,399 --> 00:50:14,399 to get light down to, you know, to a human level, 849 00:50:14,680 --> 00:50:17,399 I thought that was just absolutely fascinating. 850 00:50:18,940 --> 00:50:20,495 It is actually very odd, 851 00:50:20,496 --> 00:50:23,358 it's also extremely odd to a lot of my colleagues. 852 00:50:24,640 --> 00:50:28,799 Lene Hau created a cigar-shaped Bose-Einstein condensate 853 00:50:28,879 --> 00:50:30,720 to carry out her experiment. 854 00:50:31,360 --> 00:50:33,920 She fired a light pulse into the cloud. 855 00:50:34,399 --> 00:50:37,839 The speed of light is around a billion km/h, 856 00:50:37,840 --> 00:50:39,879 but when the pulse hits the condensate, 857 00:50:40,000 --> 00:50:43,160 it slows down to the speed of a bicycle. 858 00:50:44,679 --> 00:50:45,720 (Lene Hau) So light pulse might start out 859 00:50:45,799 --> 00:50:48,319 being 1 to 2 miles long in free space, 860 00:50:48,399 --> 00:50:49,720 it goes into our medium, 861 00:50:51,560 --> 00:50:54,080 and since the front edge enters first that will slow down. 862 00:50:54,160 --> 00:50:56,319 The back end is still in free space, that'll catch up, 863 00:50:56,720 --> 00:50:59,640 and that'll create that compression. 864 00:51:00,000 --> 00:51:02,080 And it'll end up being compressed 865 00:51:02,160 --> 00:51:06,399 from 1 to 2 miles down to 0.001 micron 866 00:51:06,480 --> 00:51:07,640 or even smaller than that. 867 00:51:08,799 --> 00:51:11,399 You could say well, gee, it's easy to stop light 868 00:51:11,480 --> 00:51:13,399 because I could just send a laser beam into a wall 869 00:51:13,480 --> 00:51:14,399 and I would stop it. 870 00:51:17,799 --> 00:51:19,799 Well, the problem is, you lose the information 871 00:51:19,879 --> 00:51:21,319 because it turns into heat. 872 00:51:21,399 --> 00:51:22,879 You can never get that information back. 873 00:51:23,000 --> 00:51:26,560 In our case, when we stop it, the information is not lost 874 00:51:26,640 --> 00:51:28,879 because that's stored in the medium, 875 00:51:28,959 --> 00:51:30,399 then we have time to revive it, 876 00:51:31,000 --> 00:51:32,160 the system has all the information 877 00:51:32,239 --> 00:51:34,160 to revive the light pulse, and it can move on. 878 00:51:37,860 --> 00:51:41,000 One day, ultra cold atoms will probably be used 879 00:51:41,160 --> 00:51:42,840 to process information 880 00:51:42,940 --> 00:51:45,840 but quite how is hard to predict. 881 00:51:50,140 --> 00:51:53,754 Sometimes the promised benefits from a scientific breakthrough 882 00:51:53,755 --> 00:51:55,458 take a long time to emerge. 883 00:51:55,858 --> 00:51:58,183 Many predicted that by this century 884 00:51:58,184 --> 00:52:00,756 energy-saving superconducting power lines 885 00:52:00,858 --> 00:52:04,920 and maglev bullet trains would be crisscrossing the continents. 886 00:52:06,458 --> 00:52:09,758 Perhaps now, whilst world's energy supplies dwindle, 887 00:52:09,858 --> 00:52:12,508 these technologies, once seen as uneconomic, 888 00:52:12,509 --> 00:52:13,998 will start to take off. 889 00:52:16,200 --> 00:52:19,460 Now it is the quantum nature of the cold frontier 890 00:52:19,461 --> 00:52:21,159 that has captured imaginations. 891 00:52:21,658 --> 00:52:23,616 Super cooled quantum devices 892 00:52:23,617 --> 00:52:26,597 are mapping the magnetic activity of the brain 893 00:52:28,160 --> 00:52:32,760 and cold atoms are being turned into quantum computers. 894 00:52:33,940 --> 00:52:33,940 895 00:52:34,540 --> 00:52:37,879 (Seth Lloyd) As a quantum mechanic, I engineer atoms. 896 00:52:40,799 --> 00:52:44,560 To make a computer out of atoms, you have to somehow get atoms 897 00:52:44,640 --> 00:52:48,000 to register information and then to process it. 898 00:52:50,480 --> 00:52:52,080 Why build quantum computers? 899 00:52:52,640 --> 00:52:56,560 Because they're cool, it's fun, and we can do it. Right? 900 00:52:56,640 --> 00:52:58,959 I mean, we actually can take atoms 901 00:52:59,319 --> 00:53:01,239 and if we ask them nicely, they'll compute. 902 00:53:01,560 --> 00:53:03,559 That's a lot of fun. I mean, have you ever 903 00:53:03,560 --> 00:53:06,640 talked to an atom recently and had it talk back? It's great! 904 00:53:06,959 --> 00:53:07,979 You know? Learn to speak atom 905 00:53:07,980 --> 00:53:09,317 and the atom speaks back. That's great. 906 00:53:14,210 --> 00:53:17,574 Quantum world is, in the world of the very small, 907 00:53:17,875 --> 00:53:21,410 is like an exotic wilderness that you've never been in before. 908 00:53:22,510 --> 00:53:26,410 And things you're wondering and everything looks strange 909 00:53:26,610 --> 00:53:28,410 and you see things that you've never seen 910 00:53:28,710 --> 00:53:31,010 but if you really want to see what's going on 911 00:53:31,510 --> 00:53:32,920 then you've got to be quiet. 912 00:53:33,010 --> 00:53:36,280 So, if you go into the wilderness and you're going "blablabla" 913 00:53:36,510 --> 00:53:38,012 then you're never going to see things 914 00:53:38,013 --> 00:53:41,519 because all these exotic phenomena are going to know that you're there 915 00:53:41,619 --> 00:53:44,110 and they're going to stay put and they're not going to come out. 916 00:53:44,210 --> 00:53:46,410 So if you make a lot of noise that's bad. 917 00:53:47,140 --> 00:53:50,799 Now, at the quantum level, at the microscopic level, 918 00:53:50,800 --> 00:53:52,508 heat is noise. 919 00:53:53,510 --> 00:53:56,792 So, if you want to see these strange and exotic effects 920 00:53:56,793 --> 00:53:58,408 you have to be quiet. 921 00:53:58,410 --> 00:53:59,610 Very quiet. 922 00:54:00,179 --> 00:54:01,479 There can't be a lot of noise 923 00:54:01,510 --> 00:54:04,080 and that means you have to cool things down. 924 00:54:06,179 --> 00:54:09,238 Unlike ordinary computers where each decision is based 925 00:54:09,239 --> 00:54:13,399 around a bit of information and is either a zero or a one, 926 00:54:14,080 --> 00:54:16,319 in the quantum world, the rules change. 927 00:54:17,799 --> 00:54:18,959 At first glance, a quantum computer 928 00:54:19,000 --> 00:54:20,399 looks almost exactly the same. 929 00:54:21,319 --> 00:54:23,399 But quantum mechanics is weird. 930 00:54:23,640 --> 00:54:25,799 It's funky, okay? It's weird. 931 00:54:28,480 --> 00:54:29,550 (Peter Shor) When you do quantum computing, 932 00:54:29,560 --> 00:54:31,439 you want to make this weirdness work for you. 933 00:54:31,899 --> 00:54:34,479 So now let's look at our quantum bit or Qbit. 934 00:54:34,480 --> 00:54:38,519 The Qbit cannot only be a zero or a one, it can also both be... 935 00:54:38,720 --> 00:54:40,016 - ...a zero and one... 936 00:54:40,017 --> 00:54:41,358 - ...at the same time. - ...same time. 937 00:54:42,160 --> 00:54:42,919 It's almost like a form of... 938 00:54:42,920 --> 00:54:44,518 - And if you look at the mini worlds - ...parallel computation, 939 00:54:44,519 --> 00:54:46,158 - ...interpretation of a quantum... - ...but in the parallel computer,... 940 00:54:46,159 --> 00:54:47,839 - ...computer... - ...one processor does this,... 941 00:54:47,840 --> 00:54:49,059 - ...what happens... - ...one processor does that. 942 00:54:49,080 --> 00:54:50,280 - ..is that your... - So you've 2 processors... 943 00:54:50,340 --> 00:54:50,919 - ...doing this and that. 944 00:54:50,920 --> 00:54:51,438 - ...quantum computer is doing many... - 945 00:54:51,440 --> 00:54:52,759 - ...quantum computer is doing many... - In a quantum computer, you've only... 946 00:54:52,760 --> 00:54:53,638 - ...many computations... - ...one processor that's... 947 00:54:53,639 --> 00:54:55,360 - ...all at the same time. - ...doing this and that... 948 00:54:55,515 --> 00:54:56,519 - ...at the same time. 949 00:55:05,340 --> 00:55:09,679 Within the giant Dewar Flask lies a prototype quantum computer 950 00:55:09,779 --> 00:55:13,480 surrounded by its supercooled, superconducting magnet. 951 00:55:15,260 --> 00:55:18,399 In the future, quantum computing could be used to predict 952 00:55:18,480 --> 00:55:19,879 quantum interactions, 953 00:55:20,239 --> 00:55:23,720 such as how a new drug acts on faulty biochemistry. 954 00:55:26,160 --> 00:55:28,799 Or to solve complex encryption problems, 955 00:55:29,160 --> 00:55:31,080 like decoding prime numbers 956 00:55:31,160 --> 00:55:34,160 that are the key to Internet credit card security. 957 00:55:36,979 --> 00:55:40,000 This weird quantum world is part of a new frontier 958 00:55:40,080 --> 00:55:43,959 opened up by the descent towards absolute zero. 959 00:55:52,080 --> 00:55:54,599 It's been a remarkable journey for scientists 960 00:55:54,799 --> 00:55:56,160 into unknown territories 961 00:55:56,339 --> 00:55:59,000 far beyond the narrow confines of Earth. 962 00:56:01,680 --> 00:56:03,781 On the Kelvin temperature scale, 963 00:56:03,782 --> 00:56:06,877 which begins at zero degrees for absolute zero, 964 00:56:07,359 --> 00:56:11,000 the temperature of the Sun is around 5000 °K. 965 00:56:12,480 --> 00:56:15,560 At 1000 °K, metals melt. 966 00:56:17,199 --> 00:56:21,280 At 300 °K, we reach what we think of as room temperature. 967 00:56:21,760 --> 00:56:24,599 Air liquifies at 100 °K, 968 00:56:26,000 --> 00:56:31,239 hydrogen at 20 °K, helium at 4 °K. 969 00:56:31,879 --> 00:56:36,239 The deepest outer space is 3 °K above absolute zero, 970 00:56:36,640 --> 00:56:39,239 the coldest place outside the laboratory. 971 00:56:40,399 --> 00:56:42,640 But the descent doesn't stop there. 972 00:56:43,399 --> 00:56:45,720 With ultra cold refrigerators, 973 00:56:45,879 --> 00:56:48,319 the decimal point shifts 3 places 974 00:56:48,399 --> 00:56:50,799 to a few 1000ths of a degree, 975 00:56:51,640 --> 00:56:53,720 and laser cooling takes it down 976 00:56:53,799 --> 00:56:56,959 3 more places to a millionth of a degree, 977 00:56:57,399 --> 00:57:00,560 the temperature of a Bose-Einstein condensate. 978 00:57:01,560 --> 00:57:05,239 With magnetic cooling, we shift 4 more decimal places 979 00:57:05,319 --> 00:57:09,439 until we reach the coldest recorded temperature in the universe, 980 00:57:09,440 --> 00:57:11,160 at a lab in Helsinki: 981 00:57:11,239 --> 00:57:13,239 100 pico Kelvin, 982 00:57:13,519 --> 00:57:19,020 or a 10th of a billionth of a degree above absolute zero. 983 00:57:21,560 --> 00:57:23,879 So will it ever be possible to go all the way, 984 00:57:24,399 --> 00:57:28,799 to reach the Holy Grail of cold, zero °K? 985 00:57:29,640 --> 00:57:31,360 (Seth Lloyd) Getting to absolute zero is tough. 986 00:57:33,539 --> 00:57:38,239 Nobody's actually been there at absolute 0.000000... 987 00:57:38,319 --> 00:57:39,560 with an infinite number of 0s. 988 00:57:40,080 --> 00:57:41,640 That last little tiny bit of heat 989 00:57:42,080 --> 00:57:45,239 becomes harder and harder to get out, and in particular, 990 00:57:45,399 --> 00:57:46,680 the time scales for getting it out 991 00:57:47,239 --> 00:57:48,560 get longer and longer and longer 992 00:57:48,640 --> 00:57:52,000 the smaller and smaller the amounts of energy involved. 993 00:57:52,399 --> 00:57:56,100 So eventually, if you're talking about extracting 994 00:57:56,180 --> 00:57:58,159 an amount of energy that's sufficiently small, 995 00:57:58,160 --> 00:58:01,339 it would indeed take the age of the universe to do it. 996 00:58:01,560 --> 00:58:03,239 Also, actually, you'd need an apparatus 997 00:58:03,319 --> 00:58:05,740 the size of the universe to do it, but that's another story! 998 00:58:08,160 --> 00:58:10,399 Absolute zero may be unreachable, 999 00:58:11,080 --> 00:58:12,979 but by exploring further and further 1000 00:58:12,980 --> 00:58:15,640 towards this ultimate destination of cold, 1001 00:58:15,920 --> 00:58:19,499 many fundamental secrets of matter have been revealed. 1002 00:58:20,319 --> 00:58:23,280 If our past was defined by our mastery of heat, 1003 00:58:23,639 --> 00:58:28,239 perhaps our future lies in the continuing conquest of cold.