WEBVTT 1 00:00:08.080 --> 00:00:11.119 - Hello, and welcome to this episode of the 2 00:00:11.119 --> 00:00:13.059 - Physics World weekly podcast, 3 00:00:13.544 --> 00:00:14.525 - which is sponsored 4 00:00:14.825 --> 00:00:16.765 - by the Shaw Prize Foundation. 5 00:00:17.785 --> 00:00:21.324 - I'm Hamish Johnston, and my guests are Kenichi 6 00:00:21.545 --> 00:00:22.045 - Namoto 7 00:00:22.664 --> 00:00:24.364 - and Stanford Woosley, 8 00:00:24.984 --> 00:00:27.725 - who share the 2026 9 00:00:28.230 --> 00:00:29.929 - Shaw prize in astronomy 10 00:00:30.390 --> 00:00:31.369 - for their studies 11 00:00:31.750 --> 00:00:33.289 - of stellar explosions 12 00:00:33.829 --> 00:00:36.090 - and the origin of the elements. 13 00:00:37.189 --> 00:00:40.309 - The Shaw prize is an international prize based 14 00:00:40.309 --> 00:00:41.450 - in Hong Kong. 15 00:00:42.195 --> 00:00:46.054 - Currently, it consists of three annual awards. 16 00:00:46.835 --> 00:00:49.094 - These are the prize in astronomy, 17 00:00:49.875 --> 00:00:52.774 - the prize in life science and medicine, 18 00:00:53.475 --> 00:00:56.215 - and the prize in mathematical sciences. 19 00:00:57.170 --> 00:00:58.950 - In 2027, 20 00:00:59.329 --> 00:01:02.869 - a fourth prize will be awarded for work 21 00:01:03.090 --> 00:01:04.549 - in computer science. 22 00:01:05.489 --> 00:01:07.670 - Each prize carries a monetary 23 00:01:07.969 --> 00:01:10.629 - award of 1,200,000 24 00:01:11.409 --> 00:01:12.230 - US dollars. 25 00:01:13.064 --> 00:01:14.444 - The prize was established 26 00:01:14.825 --> 00:01:18.685 - by Ranran Shah, a media mogul and philanthropist. 27 00:01:19.625 --> 00:01:22.765 - It was first awarded in 2004, 28 00:01:22.984 --> 00:01:26.424 - and since then, 121 29 00:01:26.424 --> 00:01:26.924 - prizes 30 00:01:27.305 --> 00:01:28.204 - have been given 31 00:01:28.750 --> 00:01:29.329 - to individuals 32 00:01:29.869 --> 00:01:31.250 - from across the world. 33 00:01:32.590 --> 00:01:35.650 - Kenichi Nomoto is emeritus professor 34 00:01:36.030 --> 00:01:38.290 - and visiting senior scientist 35 00:01:38.750 --> 00:01:40.369 - at the Kavli Institute 36 00:01:40.750 --> 00:01:42.769 - for the Physics and Mathematics 37 00:01:43.310 --> 00:01:44.129 - of the Universe 38 00:01:44.805 --> 00:01:45.545 - at Japan's 39 00:01:46.164 --> 00:01:47.545 - University of Tokyo. 40 00:01:48.484 --> 00:01:49.704 - Stanford Woosley 41 00:01:50.004 --> 00:01:52.984 - is professor of astronomy and astrophysics 42 00:01:53.685 --> 00:01:55.784 - at the University of California, 43 00:01:56.564 --> 00:01:57.465 - Santa Cruz 44 00:01:57.765 --> 00:01:58.744 - in The US. 45 00:01:59.859 --> 00:02:03.159 - Because of the large time differences between Tokyo, 46 00:02:03.859 --> 00:02:04.359 - California, 47 00:02:04.900 --> 00:02:06.040 - and my location 48 00:02:06.500 --> 00:02:07.400 - in The UK, 49 00:02:08.020 --> 00:02:10.580 - I was unable to speak to Stan and 50 00:02:10.580 --> 00:02:11.080 - Ken 51 00:02:11.379 --> 00:02:12.520 - at the same time. 52 00:02:13.294 --> 00:02:13.794 - Instead, 53 00:02:14.175 --> 00:02:15.794 - I spoke to them separately 54 00:02:16.254 --> 00:02:17.235 - for this podcast. 55 00:02:26.090 --> 00:02:28.730 - Hi, Stan. Welcome to the podcast. My first 56 00:02:28.730 --> 00:02:30.110 - question is for you. 57 00:02:31.129 --> 00:02:33.310 - Good morning, Hamish. Nice to see you. 58 00:02:34.169 --> 00:02:36.349 - So, Stan, can you give us an introduction 59 00:02:36.569 --> 00:02:37.550 - to the field? 60 00:02:38.115 --> 00:02:39.414 - What are supernovae, 61 00:02:39.955 --> 00:02:42.294 - and why do astronomers study them? 62 00:02:43.074 --> 00:02:44.995 - Well, you know, the the word kind of 63 00:02:44.995 --> 00:02:46.215 - explains it, supernova. 64 00:02:46.514 --> 00:02:47.014 - Nova, 65 00:02:47.474 --> 00:02:49.814 - a new star in the sky and super 66 00:02:50.349 --> 00:02:51.409 - really, really bright. 67 00:02:51.870 --> 00:02:52.189 - And, 68 00:02:52.830 --> 00:02:54.750 - you know, that's that's how they operate. We 69 00:02:54.750 --> 00:02:55.490 - see suddenly 70 00:02:55.949 --> 00:02:57.710 - a new a new star appear in the 71 00:02:57.710 --> 00:02:58.210 - sky. 72 00:02:58.669 --> 00:02:59.150 - About, 73 00:02:59.949 --> 00:03:01.409 - 10 times in the last 74 00:03:01.870 --> 00:03:04.574 - two thousand years, we've recorded them, though they've 75 00:03:04.574 --> 00:03:06.895 - been going on for billions of years before 76 00:03:06.895 --> 00:03:07.395 - that. 77 00:03:07.775 --> 00:03:09.235 - But it's kind of a misnomer 78 00:03:10.014 --> 00:03:12.574 - because a supernova is not a new star, 79 00:03:12.574 --> 00:03:13.875 - it's actually the death 80 00:03:14.175 --> 00:03:15.395 - of an old star. 81 00:03:16.254 --> 00:03:18.275 - And in these explosive deaths, 82 00:03:19.469 --> 00:03:21.709 - the explosions can shine with a luminosity a 83 00:03:21.709 --> 00:03:23.489 - billion times that of the sun. 84 00:03:24.110 --> 00:03:26.430 - But they're very far away because, you know, 85 00:03:26.430 --> 00:03:28.349 - the Milky Way galaxy's 100,000 86 00:03:28.349 --> 00:03:29.409 - light years across, 87 00:03:29.709 --> 00:03:31.949 - and they're scattered around that, so the ones 88 00:03:31.949 --> 00:03:34.655 - we see are mostly nearby. So even though 89 00:03:34.655 --> 00:03:37.215 - they happen every fifty years, we've only seen 90 00:03:37.215 --> 00:03:39.555 - about 10 of them in in recorded history. 91 00:03:40.254 --> 00:03:42.834 - Some of the brightest, like in October, 92 00:03:42.974 --> 00:03:44.414 - were so bright you could see them in 93 00:03:44.414 --> 00:03:46.574 - the daytime for about a month. The the 94 00:03:46.574 --> 00:03:47.875 - Crab was that way. 95 00:03:48.330 --> 00:03:50.669 - But most of the supernovae we see nowadays 96 00:03:51.050 --> 00:03:52.590 - are in other galaxies. 97 00:03:53.289 --> 00:03:56.669 - The most recent naked eye supernova was, supernova 98 00:03:56.729 --> 00:03:57.769 - 1987 99 00:03:57.769 --> 00:03:58.269 - a. 100 00:03:58.569 --> 00:04:00.110 - And I had to go down to Australia 101 00:04:00.169 --> 00:04:01.530 - to see it, but it was quite a 102 00:04:01.530 --> 00:04:03.925 - sight, a little little red jewel in the 103 00:04:03.925 --> 00:04:06.004 - middle of the Large Magellanic Cloud about as 104 00:04:06.004 --> 00:04:07.925 - bright as a star in the handle of 105 00:04:07.925 --> 00:04:08.824 - the Big Dipper. 106 00:04:09.525 --> 00:04:11.444 - But in 1987, 107 00:04:11.444 --> 00:04:14.264 - we discovered about 25 supernovae altogether. 108 00:04:15.180 --> 00:04:16.560 - This year, there will be thousands. 109 00:04:17.019 --> 00:04:18.699 - And next year, there will be tens of 110 00:04:18.699 --> 00:04:20.860 - thousands, and there's even a projection of maybe 111 00:04:20.860 --> 00:04:22.459 - a million a year in the not too 112 00:04:22.459 --> 00:04:23.360 - distant future. 113 00:04:23.660 --> 00:04:24.399 - It's incredible. 114 00:04:25.180 --> 00:04:27.740 - How many supernovae are there really? There's there's 115 00:04:27.740 --> 00:04:30.399 - about one per second in the observable universe. 116 00:04:30.834 --> 00:04:32.834 - That's an amazing number to get your head 117 00:04:32.834 --> 00:04:34.294 - around it. Somewhere 118 00:04:34.754 --> 00:04:37.474 - in in the observable universe, which is how 119 00:04:37.474 --> 00:04:39.574 - far light has gone since the big bang, 120 00:04:40.514 --> 00:04:42.134 - a star is dying catastrophically 121 00:04:42.435 --> 00:04:44.534 - and shining with a billion times the luminosity 122 00:04:44.675 --> 00:04:45.495 - of the sun. 123 00:04:46.169 --> 00:04:48.649 - Well, we see these events and astronomers in 124 00:04:48.649 --> 00:04:49.709 - their great creativity 125 00:04:50.169 --> 00:04:52.410 - have categorized them as thing one and thing 126 00:04:52.410 --> 00:04:52.910 - two, 127 00:04:53.529 --> 00:04:55.529 - or type one and type two we call 128 00:04:55.529 --> 00:04:58.649 - them. And type two supernova is one that 129 00:04:58.649 --> 00:04:59.870 - has hydrogen 130 00:05:00.329 --> 00:05:01.229 - in its spectrum, 131 00:05:02.064 --> 00:05:03.904 - kinda like the sun. The sun is mostly 132 00:05:03.904 --> 00:05:05.745 - hydrogen on its surface. In a type two 133 00:05:05.745 --> 00:05:06.245 - supernova, 134 00:05:06.865 --> 00:05:09.584 - apparently, the surface is not completely burned up 135 00:05:09.584 --> 00:05:11.425 - and we still see the the stuff it 136 00:05:11.425 --> 00:05:12.485 - was born with. 137 00:05:12.785 --> 00:05:15.185 - The other kind, type one, you don't see 138 00:05:15.185 --> 00:05:15.685 - hydrogen. 139 00:05:16.159 --> 00:05:18.419 - It's some kind of more evolved star. 140 00:05:18.959 --> 00:05:22.000 - And we know now, especially from supernova nineteen 141 00:05:22.000 --> 00:05:23.060 - eighty seven a, 142 00:05:23.519 --> 00:05:25.839 - that the type two supernovae are the deaths 143 00:05:25.839 --> 00:05:27.060 - of massive stars, 144 00:05:27.439 --> 00:05:30.259 - things much bigger than the sun. We saw 145 00:05:30.454 --> 00:05:32.855 - the progenitor of the explosion in that case. 146 00:05:32.855 --> 00:05:33.435 - It was 147 00:05:33.975 --> 00:05:36.295 - a a 20 solar mass blue supergiant, so 148 00:05:36.295 --> 00:05:38.394 - sort of sort of like Betelgeuse but only 149 00:05:38.454 --> 00:05:38.954 - blue. 150 00:05:39.975 --> 00:05:43.014 - So there's also two categories, I'm sorry to 151 00:05:43.014 --> 00:05:45.389 - say, to complicate things of type one. There's 152 00:05:45.550 --> 00:05:47.949 - one a and one b. Neither one has 153 00:05:47.949 --> 00:05:49.410 - hydrogen, but one b 154 00:05:49.870 --> 00:05:52.350 - systematically goes with the type twos. It's it's 155 00:05:52.350 --> 00:05:54.129 - a massive star explosion, 156 00:05:54.750 --> 00:05:56.910 - where the type one a's are something totally 157 00:05:56.910 --> 00:05:59.250 - different. They're exploding white dwarf stars, 158 00:05:59.564 --> 00:06:01.644 - and we've never seen the progenitor of a 159 00:06:01.644 --> 00:06:03.024 - type one a supernova. 160 00:06:03.485 --> 00:06:05.584 - So we infer a lot from the models. 161 00:06:05.805 --> 00:06:07.884 - There's a lot of observations, but we still 162 00:06:07.884 --> 00:06:10.524 - haven't seen the progenitor just before it blew 163 00:06:10.524 --> 00:06:11.584 - up in that case. 164 00:06:12.810 --> 00:06:15.209 - Now supernovae are not only big and bright 165 00:06:15.209 --> 00:06:17.129 - and and very impressive. And by the way, 166 00:06:17.129 --> 00:06:19.529 - the sun will never be a supernova. It's 167 00:06:19.529 --> 00:06:21.689 - it's not big enough. It'll end up as 168 00:06:21.689 --> 00:06:24.250 - a white dwarf. It's only the rare massive 169 00:06:24.250 --> 00:06:27.069 - stars that become supernovae type too. 170 00:06:27.664 --> 00:06:29.904 - But they they do other things besides glow 171 00:06:29.904 --> 00:06:32.985 - brightly. They also give birth to to some 172 00:06:32.985 --> 00:06:35.104 - of the most exotic objects in the universe, 173 00:06:35.104 --> 00:06:37.044 - black holes and neutron stars. 174 00:06:37.504 --> 00:06:39.985 - When we look in the the remnant of 175 00:06:39.985 --> 00:06:41.285 - the Crabbe supernova, 176 00:06:41.930 --> 00:06:43.310 - we see a pulsar, 177 00:06:43.689 --> 00:06:46.730 - a a rapidly rotating neutron star 33 times 178 00:06:46.730 --> 00:06:49.209 - a second. And we see black holes of 179 00:06:49.209 --> 00:06:52.830 - of several and sometimes ten, twenty solar masses 180 00:06:53.290 --> 00:06:55.209 - scattered around our galaxy. And the only way 181 00:06:55.209 --> 00:06:57.444 - those can have been made is in supernovae. 182 00:06:57.665 --> 00:06:58.725 - So they not only 183 00:06:59.025 --> 00:07:01.985 - are dramatic explosions and brilliant, but they they 184 00:07:01.985 --> 00:07:03.985 - leave behind very interesting, 185 00:07:04.384 --> 00:07:04.884 - objects. 186 00:07:05.425 --> 00:07:07.824 - But the final thing which I find most 187 00:07:07.824 --> 00:07:09.665 - interesting, and and this is largely what Ken 188 00:07:09.665 --> 00:07:11.045 - and I have been noted for, 189 00:07:11.459 --> 00:07:13.459 - is that they are fountains of creation. They 190 00:07:13.459 --> 00:07:14.920 - they make the heavy elements. 191 00:07:15.379 --> 00:07:17.220 - The stuff you and I and the ocean 192 00:07:17.220 --> 00:07:18.660 - and the earth and the mountains are made 193 00:07:18.660 --> 00:07:21.139 - out of, it was almost all made in 194 00:07:21.139 --> 00:07:22.100 - a 100,000,000 195 00:07:22.100 --> 00:07:24.279 - supernovae before the sun was born. 196 00:07:24.814 --> 00:07:27.294 - And so we are stardust or or more 197 00:07:27.294 --> 00:07:28.274 - correctly, we're actively 198 00:07:28.894 --> 00:07:29.794 - star fallout. 199 00:07:31.774 --> 00:07:34.735 - And and, Stan, what was it like in 200 00:07:34.735 --> 00:07:36.034 - 1987? 201 00:07:36.574 --> 00:07:39.055 - I assume by that time, you had you 202 00:07:39.055 --> 00:07:39.794 - had studied 203 00:07:40.699 --> 00:07:41.199 - supernovae, 204 00:07:42.300 --> 00:07:44.860 - for some time. And then you went to 205 00:07:44.860 --> 00:07:47.660 - Australia, and you actually got to to see 206 00:07:47.660 --> 00:07:48.939 - one. That must have been 207 00:07:49.340 --> 00:07:51.259 - I mean, that must have been a very 208 00:07:51.259 --> 00:07:51.759 - exciting 209 00:07:52.139 --> 00:07:53.680 - time for you, was it? 210 00:07:54.134 --> 00:07:55.654 - I should say see one with your with 211 00:07:55.654 --> 00:07:57.654 - the naked eye. I'm sure you've seen them 212 00:07:57.654 --> 00:08:00.774 - in telescope images. Supernova eighty seven a was 213 00:08:00.774 --> 00:08:03.254 - was simply amazing. I couldn't believe it. I 214 00:08:03.254 --> 00:08:04.774 - thought it must be a joke. I saw 215 00:08:04.774 --> 00:08:07.014 - someone sent around an IU circular, bathed it 216 00:08:07.014 --> 00:08:09.449 - up. And when it became real, my whole 217 00:08:09.449 --> 00:08:11.689 - life changed. And and for for so many 218 00:08:11.689 --> 00:08:14.189 - of us, it was such an international collaboration. 219 00:08:14.410 --> 00:08:17.550 - You know? There were observations coming from X-ray 220 00:08:17.610 --> 00:08:20.029 - satellites in Japan and supernova 221 00:08:20.714 --> 00:08:23.855 - observatory observations in South Africa and Chile, 222 00:08:24.475 --> 00:08:26.955 - and, gamma rays were being observed from the 223 00:08:26.955 --> 00:08:29.675 - Mir spacecraft by the Soviet Union. And we 224 00:08:29.675 --> 00:08:31.675 - were all collaborating. It was just one great 225 00:08:31.675 --> 00:08:34.029 - big happy party, and that went on for 226 00:08:34.029 --> 00:08:35.990 - a couple of years. And I I traveled 227 00:08:35.990 --> 00:08:37.049 - all over the place, 228 00:08:37.909 --> 00:08:39.690 - and one of them was to Australia 229 00:08:40.309 --> 00:08:42.309 - where I got to the privilege of of 230 00:08:42.309 --> 00:08:44.309 - going out in a field with Rob McNaught, 231 00:08:44.309 --> 00:08:46.090 - who actually was one of the discoverers 232 00:08:46.789 --> 00:08:47.110 - of the 233 00:08:48.634 --> 00:08:51.115 - of of supernova eighty seven. Ian Shelton actually 234 00:08:51.115 --> 00:08:53.835 - discovered it, but Rob McNaught, by peculiarity and 235 00:08:53.835 --> 00:08:56.154 - history, saw it first and didn't realize it. 236 00:08:56.154 --> 00:08:57.215 - But he showed me 237 00:08:57.674 --> 00:09:00.154 - my first real supernova and pointed out the 238 00:09:00.154 --> 00:09:01.215 - LMC because 239 00:09:01.595 --> 00:09:03.375 - being from California, I'd never 240 00:09:03.754 --> 00:09:05.649 - seen it. And sure enough, you could see 241 00:09:05.649 --> 00:09:07.809 - this little red jewel shining right in the 242 00:09:07.809 --> 00:09:10.370 - middle of that cloud. And it was it 243 00:09:10.370 --> 00:09:11.970 - was really an impressive thing. You know, I 244 00:09:11.970 --> 00:09:14.610 - study these things in in theory all my 245 00:09:14.610 --> 00:09:16.769 - life and here here was one shining that 246 00:09:16.769 --> 00:09:18.470 - I could actually reach out and see. 247 00:09:18.995 --> 00:09:21.235 - And and that's you you've touched on an 248 00:09:21.235 --> 00:09:24.375 - interesting point about supernovae as well that 249 00:09:24.834 --> 00:09:25.894 - that people 250 00:09:26.754 --> 00:09:28.934 - observe them across many different, 251 00:09:29.794 --> 00:09:32.440 - wavelengths of light. And I think am am 252 00:09:32.440 --> 00:09:34.460 - I right in thinking we've also seen neutrinos 253 00:09:34.679 --> 00:09:35.179 - from, 254 00:09:36.120 --> 00:09:37.659 - from events as well? 255 00:09:38.360 --> 00:09:40.679 - Yeah. I that was the most incredible part 256 00:09:40.679 --> 00:09:43.419 - of all, and I'm sorry I omitted that. 257 00:09:43.559 --> 00:09:44.620 - But in in, 258 00:09:45.535 --> 00:09:46.035 - Kamiokande, 259 00:09:46.495 --> 00:09:48.915 - in Irvine, Michigan, Brookhaven, in, 260 00:09:50.095 --> 00:09:52.035 - Mount Blanc, they saw neutrinos 261 00:09:52.735 --> 00:09:55.295 - from '87 a about a dozen, but this 262 00:09:55.295 --> 00:09:57.215 - was an event a 160,000 263 00:09:57.215 --> 00:09:59.620 - light years away, and a neutrino can go 264 00:09:59.620 --> 00:10:01.000 - through a light year of lead. 265 00:10:01.460 --> 00:10:03.460 - So just to capture that dozen was an 266 00:10:03.460 --> 00:10:06.580 - incredible feat and it told us that, yeah, 267 00:10:06.580 --> 00:10:08.340 - you're you're you're kind of right. 268 00:10:08.820 --> 00:10:10.820 - These supernova happen when the core of a 269 00:10:10.820 --> 00:10:13.304 - massive star collapses to a neutron star 270 00:10:13.625 --> 00:10:14.924 - and radiates away 271 00:10:16.585 --> 00:10:18.424 - 20% of the rest mass of the sun 272 00:10:18.424 --> 00:10:19.245 - in neutrinos. 273 00:10:20.184 --> 00:10:20.684 - Incredible. 274 00:10:22.024 --> 00:10:22.524 - Ken, 275 00:10:22.825 --> 00:10:25.625 - much of your career has focused on type 276 00:10:25.625 --> 00:10:27.164 - one a supernovae. 277 00:10:27.909 --> 00:10:28.730 - Can you describe 278 00:10:29.269 --> 00:10:30.090 - this phenomenon? 279 00:10:30.789 --> 00:10:34.009 - Okay. The there exists two types of supernovae, 280 00:10:34.149 --> 00:10:34.649 - basically. 281 00:10:35.429 --> 00:10:35.750 - And, 282 00:10:36.789 --> 00:10:37.289 - food's 283 00:10:37.669 --> 00:10:40.809 - spectra shows the existence of hydrogen and helium, 284 00:10:41.190 --> 00:10:42.615 - which are called type twos. 285 00:10:43.654 --> 00:10:44.714 - And, type one 286 00:10:45.495 --> 00:10:47.914 - does not show hydrogen or helium. 287 00:10:48.375 --> 00:10:50.695 - The hydrogen and the helium are formed from 288 00:10:50.695 --> 00:10:51.514 - the big barn, 289 00:10:52.615 --> 00:10:55.115 - so normal stars should have hydrogen and helium. 290 00:10:58.500 --> 00:11:00.200 - So without hydrogen helium, 291 00:11:00.820 --> 00:11:04.019 - the exploding stars of type one a should 292 00:11:04.019 --> 00:11:04.519 - be 293 00:11:04.899 --> 00:11:05.879 - a very special 294 00:11:06.500 --> 00:11:07.000 - supernova, 295 00:11:07.940 --> 00:11:09.465 - and that is quite rough. 296 00:11:10.425 --> 00:11:10.925 - And, 297 00:11:11.705 --> 00:11:13.404 - so let me explain why 298 00:11:13.785 --> 00:11:17.245 - there exist basically two types of supernovae 299 00:11:18.665 --> 00:11:21.480 - without without without without hydrogen, for example. 300 00:11:24.279 --> 00:11:26.940 - And, then it depends on the stellar evolution. 301 00:11:27.720 --> 00:11:28.220 - The 302 00:11:28.839 --> 00:11:31.720 - evolution of stars from its birth to the 303 00:11:31.720 --> 00:11:32.220 - end 304 00:11:33.159 --> 00:11:35.399 - depends on the mass of the high mass 305 00:11:35.399 --> 00:11:36.699 - of the stars that 306 00:11:37.074 --> 00:11:39.095 - formed from the interstellar gas. 307 00:11:39.875 --> 00:11:40.375 - And, 308 00:11:40.995 --> 00:11:42.214 - so if the stars, 309 00:11:43.794 --> 00:11:45.014 - more massive than 310 00:11:45.475 --> 00:11:48.595 - 10 solar mass solar mass mass of the 311 00:11:48.595 --> 00:11:48.929 - sun, 312 00:11:50.289 --> 00:11:50.789 - Then 313 00:11:51.490 --> 00:11:51.649 - the, 314 00:11:52.370 --> 00:11:54.230 - stars are big enough to contract 315 00:11:55.009 --> 00:11:57.429 - and eventually forming iron 316 00:11:58.210 --> 00:12:00.470 - in the core and collapse and 317 00:12:00.929 --> 00:12:02.789 - to become a type two supernovae. 318 00:12:03.825 --> 00:12:04.225 - And, 319 00:12:05.745 --> 00:12:08.485 - the stars below eight solar eight solar mass, 320 00:12:09.264 --> 00:12:11.205 - like the sun, our sun, 321 00:12:11.785 --> 00:12:12.285 - we 322 00:12:12.945 --> 00:12:14.644 - it was deep completely differently. 323 00:12:16.304 --> 00:12:17.524 - They are not 324 00:12:17.985 --> 00:12:18.750 - heavy enough 325 00:12:19.470 --> 00:12:20.929 - to continue to contract. 326 00:12:22.350 --> 00:12:22.850 - So 327 00:12:23.309 --> 00:12:23.809 - the 328 00:12:25.230 --> 00:12:26.450 - the pressure of electrons 329 00:12:27.070 --> 00:12:28.129 - are strong enough 330 00:12:28.590 --> 00:12:30.049 - to prevent the contraction 331 00:12:30.590 --> 00:12:31.090 - after 332 00:12:31.695 --> 00:12:34.595 - carbon and oxygen core is formed from 333 00:12:35.375 --> 00:12:36.514 - the burning of helium. 334 00:12:37.455 --> 00:12:37.695 - And, 335 00:12:40.014 --> 00:12:40.514 - then 336 00:12:42.575 --> 00:12:44.595 - the the star, for example, 337 00:12:45.159 --> 00:12:47.100 - future sun consists of 338 00:12:47.480 --> 00:12:48.059 - the core 339 00:12:48.679 --> 00:12:50.539 - of the, carbon and oxygen 340 00:12:51.000 --> 00:12:51.500 - and 341 00:12:51.879 --> 00:12:52.379 - plus 342 00:12:52.759 --> 00:12:54.059 - envelope which contains, 343 00:12:54.519 --> 00:12:56.220 - basically, hydrogen and helium. 344 00:12:57.559 --> 00:13:00.860 - And the core is contracting, and the envelope 345 00:13:01.024 --> 00:13:02.485 - of hydrogen and helium 346 00:13:03.024 --> 00:13:03.524 - expands 347 00:13:03.904 --> 00:13:05.585 - to a to to be a so called 348 00:13:05.585 --> 00:13:06.404 - red giant. 349 00:13:07.105 --> 00:13:07.845 - And, eventually, 350 00:13:09.105 --> 00:13:12.625 - those hydrogen helium envelope is lost from the 351 00:13:12.625 --> 00:13:13.125 - core 352 00:13:13.664 --> 00:13:16.629 - by the pressure of the radiation, the pressure 353 00:13:16.629 --> 00:13:17.209 - of the 354 00:13:17.509 --> 00:13:18.809 - photons. And 355 00:13:19.190 --> 00:13:19.690 - then 356 00:13:20.470 --> 00:13:23.129 - the the star becomes just the core 357 00:13:24.230 --> 00:13:25.610 - of an ocean, 358 00:13:26.470 --> 00:13:29.269 - and which which is just going to cool 359 00:13:29.269 --> 00:13:29.769 - down, 360 00:13:30.629 --> 00:13:34.084 - becoming a white dwarf. Dwarf means, the compact 361 00:13:34.084 --> 00:13:37.144 - star, like the size of the the Earth. 362 00:13:38.324 --> 00:13:39.524 - But the mass is 363 00:13:40.084 --> 00:13:42.884 - or be about point six four mass of 364 00:13:42.884 --> 00:13:44.105 - the sun, but 365 00:13:45.445 --> 00:13:46.264 - it's very, 366 00:13:46.964 --> 00:13:48.830 - dense, that compass system. 367 00:13:49.850 --> 00:13:51.549 - Yeah, that is a white dwarf. 368 00:13:52.250 --> 00:13:52.750 - So 369 00:13:54.089 --> 00:13:55.070 - in that sense, 370 00:13:55.850 --> 00:13:57.529 - just start divided into the, 371 00:13:58.409 --> 00:14:00.889 - type two supernovae and the formation of the 372 00:14:00.889 --> 00:14:01.710 - white dwarf. 373 00:14:02.815 --> 00:14:03.555 - Two types, basically. 374 00:14:04.575 --> 00:14:07.455 - And, which I I will discuss later, the 375 00:14:07.455 --> 00:14:08.355 - stars between 376 00:14:08.975 --> 00:14:10.835 - eight to tensor mass 377 00:14:11.535 --> 00:14:14.654 - also evolved a bit it's differently, including electron 378 00:14:14.654 --> 00:14:17.459 - capture supernovae, which I I will discuss later. 379 00:14:18.000 --> 00:14:21.059 - The white dwarf itself is just cooling stars 380 00:14:21.679 --> 00:14:23.699 - and does not does not explode. 381 00:14:24.879 --> 00:14:26.439 - In other words, the sun does not become 382 00:14:26.439 --> 00:14:27.139 - a supernova. 383 00:14:28.399 --> 00:14:31.004 - But if the white dwarf is 384 00:14:31.865 --> 00:14:33.804 - included in the closed binaries, 385 00:14:35.065 --> 00:14:35.884 - there is a companion 386 00:14:36.345 --> 00:14:37.325 - stars that 387 00:14:38.024 --> 00:14:38.524 - they, 388 00:14:39.144 --> 00:14:41.545 - trigger the explosion of white dwarf, which I 389 00:14:41.545 --> 00:14:42.845 - will discuss later. 390 00:14:43.465 --> 00:14:43.965 - Yeah. 391 00:14:45.330 --> 00:14:46.710 - So but that's why 392 00:14:47.089 --> 00:14:49.409 - there's the two types of the final fate 393 00:14:49.409 --> 00:14:50.230 - of the stars, 394 00:14:51.009 --> 00:14:53.970 - very massive type two supernovae and, very small 395 00:14:53.970 --> 00:14:55.029 - mass white dwarfs. 396 00:14:55.570 --> 00:14:55.889 - And, 397 00:14:56.450 --> 00:14:58.850 - in binaries, that could become type one, a 398 00:14:58.850 --> 00:14:59.350 - supernovae. 399 00:15:00.129 --> 00:15:02.524 - And, Ken, I wanted to ask you about 400 00:15:02.904 --> 00:15:03.964 - a very famous 401 00:15:04.345 --> 00:15:05.964 - supernova called the Crab 402 00:15:06.345 --> 00:15:08.424 - supernova, which I think you have done a 403 00:15:08.424 --> 00:15:09.564 - lot of work on. 404 00:15:10.504 --> 00:15:11.804 - This is thought to 405 00:15:12.184 --> 00:15:13.549 - have been created 406 00:15:14.009 --> 00:15:15.769 - by or or I should say the Crab 407 00:15:15.769 --> 00:15:18.590 - Nebula Mhmm. Is thought to have been created 408 00:15:18.649 --> 00:15:20.110 - by an electron 409 00:15:20.410 --> 00:15:20.910 - capture 410 00:15:21.370 --> 00:15:23.529 - supernova. Can can you talk a bit about 411 00:15:23.529 --> 00:15:24.269 - that event? 412 00:15:24.889 --> 00:15:25.389 - Okay. 413 00:15:25.804 --> 00:15:26.304 - The 414 00:15:26.924 --> 00:15:27.964 - the cloud is, 415 00:15:28.924 --> 00:15:30.704 - very well observed, but 416 00:15:31.485 --> 00:15:32.225 - and data 417 00:15:32.845 --> 00:15:33.345 - clearly 418 00:15:33.804 --> 00:15:36.144 - a remnant of the supernova explosions 419 00:15:36.524 --> 00:15:38.784 - because that forms a neutron star inside 420 00:15:39.404 --> 00:15:42.019 - that is very clearly seen. But as the 421 00:15:42.019 --> 00:15:44.679 - klebonylure is not not a typical 422 00:15:45.139 --> 00:15:47.159 - remnant of supernova explosions 423 00:15:47.940 --> 00:15:48.440 - because 424 00:15:49.139 --> 00:15:50.120 - its expansion 425 00:15:51.860 --> 00:15:53.159 - energy is 426 00:15:54.019 --> 00:15:54.659 - less than 427 00:15:55.835 --> 00:15:58.654 - 10 times less than the ordinary supermodel elements, 428 00:15:58.955 --> 00:16:00.095 - very weak explosions. 429 00:16:00.875 --> 00:16:03.615 - And it contains not much heavy elements, 430 00:16:04.715 --> 00:16:06.815 - which should have been produced in the explosion 431 00:16:07.035 --> 00:16:08.174 - ordinary supermodel, 432 00:16:08.715 --> 00:16:09.659 - but crab doesn't. 433 00:16:10.940 --> 00:16:13.759 - So their CREB is very different from 434 00:16:14.059 --> 00:16:14.559 - typical 435 00:16:15.259 --> 00:16:16.240 - supernova remnant. 436 00:16:18.299 --> 00:16:18.799 - Then 437 00:16:19.819 --> 00:16:21.039 - the case of the, 438 00:16:21.899 --> 00:16:23.279 - the electron capture supernovae, 439 00:16:23.955 --> 00:16:24.855 - which I mentioned, 440 00:16:25.795 --> 00:16:27.735 - comes from the stars between 441 00:16:28.595 --> 00:16:30.535 - probably around nine solar mass. 442 00:16:31.475 --> 00:16:33.894 - The as I said, the 443 00:16:35.154 --> 00:16:35.815 - the stars 444 00:16:36.529 --> 00:16:39.350 - between eight solar mass and 10 solar mass, 445 00:16:39.730 --> 00:16:40.230 - they 446 00:16:40.610 --> 00:16:41.509 - burn carbon 447 00:16:42.049 --> 00:16:44.149 - during its evolution and forming 448 00:16:44.689 --> 00:16:46.389 - the core of oxygen, 449 00:16:46.929 --> 00:16:48.069 - neon, magnesium. 450 00:16:49.490 --> 00:16:49.725 - And 451 00:16:51.644 --> 00:16:52.144 - then 452 00:16:53.004 --> 00:16:53.504 - the 453 00:16:54.444 --> 00:16:56.225 - the contraction of 454 00:16:56.684 --> 00:16:57.664 - the core stops. 455 00:16:58.365 --> 00:16:59.105 - So, basically, 456 00:16:59.804 --> 00:17:01.985 - the for example, eight to 457 00:17:02.365 --> 00:17:04.920 - nine for a mass case, lower lower side 458 00:17:04.920 --> 00:17:06.380 - of of that mass range 459 00:17:07.160 --> 00:17:07.660 - becomes 460 00:17:09.319 --> 00:17:10.140 - a forming 461 00:17:11.079 --> 00:17:13.339 - oxygen near magnesium white dwarf, 462 00:17:14.839 --> 00:17:18.039 - similar to the carbon oxygen white dwarf below 463 00:17:18.039 --> 00:17:19.325 - eight for a mass. But 464 00:17:19.984 --> 00:17:20.484 - the 465 00:17:21.144 --> 00:17:21.644 - stars, 466 00:17:22.024 --> 00:17:24.424 - for example, around nine to 10 solar mass, 467 00:17:24.424 --> 00:17:25.644 - slightly above it, 468 00:17:27.224 --> 00:17:28.204 - we can contract 469 00:17:28.585 --> 00:17:30.044 - to a very high density. 470 00:17:31.384 --> 00:17:31.884 - And 471 00:17:33.680 --> 00:17:35.460 - the density becomes high enough 472 00:17:36.400 --> 00:17:37.619 - for the electrons 473 00:17:39.119 --> 00:17:39.619 - captured 474 00:17:40.240 --> 00:17:41.460 - absorbed by 475 00:17:42.000 --> 00:17:44.025 - the neon and magnesium, for example. 476 00:17:45.065 --> 00:17:48.125 - So the number of number fraction of electron 477 00:17:48.345 --> 00:17:48.845 - decrease. 478 00:17:49.785 --> 00:17:50.605 - So the pressure 479 00:17:51.305 --> 00:17:53.085 - of electrons decrease, and that 480 00:17:54.105 --> 00:17:55.484 - induce the collapse 481 00:17:56.025 --> 00:17:58.205 - of the oxygen near magnesium core. 482 00:17:59.269 --> 00:18:00.411 - And that makes, 483 00:18:00.862 --> 00:18:03.568 - white are the explosions supernova type 484 00:18:04.019 --> 00:18:06.089 - basically, type two similar to type two, 485 00:18:07.269 --> 00:18:07.769 - but 486 00:18:08.549 --> 00:18:09.049 - the 487 00:18:09.509 --> 00:18:11.769 - the collapsing core of oxygen near magnesium 488 00:18:12.549 --> 00:18:13.049 - is 489 00:18:14.125 --> 00:18:15.744 - smaller than iron core. 490 00:18:17.005 --> 00:18:18.784 - So its explosion energy 491 00:18:19.644 --> 00:18:20.544 - in in calculation 492 00:18:21.644 --> 00:18:22.544 - is quite small 493 00:18:23.644 --> 00:18:25.424 - and less than 10 times 494 00:18:26.284 --> 00:18:28.384 - 10 times less than the water in super 495 00:18:28.605 --> 00:18:29.730 - explosion models. 496 00:18:30.690 --> 00:18:31.190 - And, 497 00:18:31.650 --> 00:18:32.150 - also, 498 00:18:32.529 --> 00:18:33.349 - it ejects 499 00:18:33.890 --> 00:18:35.269 - only the outer envelope 500 00:18:35.650 --> 00:18:36.150 - material, 501 00:18:36.849 --> 00:18:38.390 - so not much heavy elements. 502 00:18:39.490 --> 00:18:41.269 - So so those features, 503 00:18:42.849 --> 00:18:43.669 - not typical 504 00:18:44.275 --> 00:18:45.555 - compared with the ordinary, 505 00:18:46.674 --> 00:18:48.934 - super type two supernova explosions, 506 00:18:50.275 --> 00:18:53.075 - but it's very similar to the for what 507 00:18:53.075 --> 00:18:54.855 - we are observing in kravniviera. 508 00:18:56.250 --> 00:18:56.750 - Both 509 00:18:57.369 --> 00:18:59.390 - are different from typical one. 510 00:19:00.329 --> 00:19:00.829 - Observationally, 511 00:19:01.690 --> 00:19:02.430 - not typical, 512 00:19:02.890 --> 00:19:05.849 - and, electron capture superman will be theoretically not 513 00:19:05.849 --> 00:19:06.349 - typical. 514 00:19:07.609 --> 00:19:09.150 - So that's why I suggested 515 00:19:09.849 --> 00:19:11.855 - the Crab Nebula is formed from 516 00:19:12.554 --> 00:19:13.054 - the, 517 00:19:14.154 --> 00:19:15.454 - electron capture supernovae 518 00:19:15.755 --> 00:19:18.894 - around probably nine to 10 solar mass range, 519 00:19:19.674 --> 00:19:21.535 - lower end of the quark supernovae. 520 00:19:22.554 --> 00:19:24.234 - And that's, Ken, that's one thing that I 521 00:19:24.234 --> 00:19:25.294 - really like about 522 00:19:25.674 --> 00:19:26.174 - supernovae 523 00:19:26.474 --> 00:19:27.134 - is that 524 00:19:27.779 --> 00:19:30.100 - it's a lot of nuclear physics, isn't it? 525 00:19:30.100 --> 00:19:32.340 - I mean, do you consider yourself a a 526 00:19:32.340 --> 00:19:32.840 - nuclear 527 00:19:33.299 --> 00:19:33.799 - physicist? 528 00:19:34.420 --> 00:19:36.500 - Is that how you would describe yourself? Or 529 00:19:36.500 --> 00:19:37.880 - are you more of an astrophysicist? 530 00:19:38.900 --> 00:19:40.900 - Because I'm guessing you spent a lot of 531 00:19:40.900 --> 00:19:41.400 - time 532 00:19:42.204 --> 00:19:44.625 - doing nuclear physics. I am astrophysicist 533 00:19:45.164 --> 00:19:45.664 - and 534 00:19:46.204 --> 00:19:48.144 - kind of user of nuclear physics. 535 00:19:49.804 --> 00:19:51.264 - So I have to know 536 00:19:51.724 --> 00:19:54.224 - the new the physics of nuclear 537 00:19:54.924 --> 00:19:56.224 - nuclear materials and 538 00:19:56.720 --> 00:19:58.880 - for the equation of state and so on, 539 00:19:58.880 --> 00:19:59.380 - but 540 00:20:00.160 --> 00:20:01.380 - and the nuclear reactions. 541 00:20:02.320 --> 00:20:02.559 - But, 542 00:20:03.200 --> 00:20:04.180 - we are not 543 00:20:04.960 --> 00:20:07.380 - developing reaction rate by by ourselves. 544 00:20:07.759 --> 00:20:09.700 - So we we believe 545 00:20:10.079 --> 00:20:12.180 - a nuclear physicist can do it properly. 546 00:20:13.015 --> 00:20:14.855 - Well, that's great. We're gonna talk we're gonna 547 00:20:14.855 --> 00:20:15.755 - talk some more, 548 00:20:16.454 --> 00:20:16.954 - about, 549 00:20:17.494 --> 00:20:19.115 - nuclear physics and nucleosynthesis 550 00:20:19.974 --> 00:20:21.434 - a bit later in the podcast. 551 00:20:22.214 --> 00:20:24.375 - But now I'm going to go, my next 552 00:20:24.375 --> 00:20:24.875 - question 553 00:20:25.460 --> 00:20:26.599 - is for Stan. 554 00:20:27.059 --> 00:20:29.320 - Stan, you've done a lot of work on 555 00:20:29.380 --> 00:20:30.119 - type two 556 00:20:30.500 --> 00:20:31.000 - supernovae. 557 00:20:31.619 --> 00:20:32.519 - What distinguishes 558 00:20:32.900 --> 00:20:33.400 - these, 559 00:20:33.859 --> 00:20:35.880 - events from type one a 560 00:20:36.259 --> 00:20:36.759 - supernovae? 561 00:20:37.299 --> 00:20:39.460 - Well, type type one a is is an 562 00:20:39.460 --> 00:20:40.920 - entirely different thing. 563 00:20:41.565 --> 00:20:43.884 - It's the explosion of a white dwarf interacting 564 00:20:43.884 --> 00:20:45.184 - in a binary system, 565 00:20:45.484 --> 00:20:47.105 - as as Ken has been describing. 566 00:20:47.964 --> 00:20:50.384 - A type two and and a 1b also, 567 00:20:51.404 --> 00:20:53.244 - is the end of the life of a 568 00:20:53.244 --> 00:20:55.404 - star more than eight times the mass of 569 00:20:55.404 --> 00:20:56.224 - of the sun. 570 00:20:56.840 --> 00:20:59.720 - The sun is not big enough to become 571 00:20:59.720 --> 00:21:00.460 - a supernova. 572 00:21:00.920 --> 00:21:03.640 - It can fuse hydrogen to helium like it's 573 00:21:03.640 --> 00:21:05.640 - doing now and will for five billion more 574 00:21:05.640 --> 00:21:07.880 - years, and then it can turn helium into 575 00:21:07.880 --> 00:21:08.940 - carbon and oxygen, 576 00:21:09.365 --> 00:21:10.965 - but that's the end of the road for 577 00:21:10.965 --> 00:21:12.644 - the sun. It's just not big enough to 578 00:21:12.644 --> 00:21:16.184 - go on. But massive stars fuse carbon into 579 00:21:16.404 --> 00:21:19.125 - neon and magnesium and oxygen into silicon and 580 00:21:19.125 --> 00:21:21.065 - sulfur and silicon into 581 00:21:21.684 --> 00:21:23.769 - iron. And so, you know, it just keeps 582 00:21:23.769 --> 00:21:25.470 - on going, but there is an endpoint 583 00:21:25.930 --> 00:21:27.609 - in that once you've made iron, you can 584 00:21:27.609 --> 00:21:29.710 - get no more energy out of nuclear fusion. 585 00:21:30.250 --> 00:21:31.690 - So you end up with a star with 586 00:21:31.690 --> 00:21:34.250 - a composition kind of like a spherical layer 587 00:21:34.250 --> 00:21:36.704 - cake or a Russian doll set with a 588 00:21:36.704 --> 00:21:38.785 - core of iron and a shell of silicon 589 00:21:38.785 --> 00:21:40.804 - and a shell of oxygen and so on. 590 00:21:40.865 --> 00:21:43.105 - But the iron core can't support itself, it 591 00:21:43.105 --> 00:21:45.044 - has no more source of nuclear energy, 592 00:21:45.424 --> 00:21:47.505 - so it collapses and there's nothing to stop 593 00:21:47.505 --> 00:21:49.525 - the collapse and it collapses all the way 594 00:21:49.669 --> 00:21:51.589 - to the density of the atomic nucleus to 595 00:21:51.589 --> 00:21:52.809 - a neutron star. 596 00:21:53.349 --> 00:21:55.829 - And in the process, it radiates, as we 597 00:21:55.829 --> 00:21:58.409 - mentioned before, this stupendous flux of neutrinos. 598 00:22:00.390 --> 00:22:02.390 - 10 to the 58 of them, I believe 599 00:22:02.390 --> 00:22:04.710 - it is. 20% of the rest mass of 600 00:22:04.710 --> 00:22:05.289 - the sun. 601 00:22:06.005 --> 00:22:07.144 - And those neutrinos, 602 00:22:07.444 --> 00:22:09.524 - for the most part, just stream out and 603 00:22:09.524 --> 00:22:10.664 - are never seen again. 604 00:22:11.284 --> 00:22:13.924 - But of the order 1% of them capturing 605 00:22:13.924 --> 00:22:16.744 - the material outside of this collapsing iron core 606 00:22:17.125 --> 00:22:18.984 - and push on it and cause a shockwave 607 00:22:19.044 --> 00:22:21.359 - to be born. And so it pushes out 608 00:22:21.359 --> 00:22:23.759 - all of these ashes of the previous burning 609 00:22:23.759 --> 00:22:26.820 - of carbon burning and oxygen and silicon burning, 610 00:22:27.039 --> 00:22:29.359 - pushes them out into the interstellar medium and 611 00:22:29.359 --> 00:22:32.384 - it also pushes out some radioactive nickel 56. 612 00:22:33.184 --> 00:22:35.505 - And it makes a shockwave that interacts with 613 00:22:35.505 --> 00:22:37.365 - the envelope of the star 614 00:22:37.825 --> 00:22:40.305 - and as that envelope expands and dumps the 615 00:22:40.305 --> 00:22:42.085 - energy that the shockwave deposited, 616 00:22:42.464 --> 00:22:44.704 - you get a long, several month long, very 617 00:22:44.704 --> 00:22:45.525 - bright supernova. 618 00:22:46.140 --> 00:22:48.380 - And then the radioactive nickel, which we've actually 619 00:22:48.380 --> 00:22:51.119 - seen in many supernovae now, makes a tail 620 00:22:51.500 --> 00:22:52.799 - on that light curve. 621 00:22:53.259 --> 00:22:54.720 - And so go you go back 622 00:22:55.099 --> 00:22:57.420 - millennia later and you see the neutron star 623 00:22:57.420 --> 00:23:00.160 - there or maybe a black hole got made 624 00:23:00.565 --> 00:23:03.785 - and you see this remnant of of ashes 625 00:23:04.085 --> 00:23:07.125 - expanding at thousands of kilometers per second made 626 00:23:07.125 --> 00:23:09.705 - out of silicon, sulfur, and and so on, 627 00:23:10.164 --> 00:23:12.005 - the stuff that someday will make a million 628 00:23:12.005 --> 00:23:12.505 - Earths. 629 00:23:13.069 --> 00:23:15.309 - And so it it turns out that a 630 00:23:15.309 --> 00:23:16.289 - type two supernova, 631 00:23:17.549 --> 00:23:20.109 - although not widely appreciated, is is mostly a 632 00:23:20.109 --> 00:23:21.250 - neutrino explosion. 633 00:23:21.950 --> 00:23:23.869 - Most of the energy comes out in in 634 00:23:23.869 --> 00:23:24.369 - neutrinos. 635 00:23:25.815 --> 00:23:27.894 - 1% of that energy comes out in the 636 00:23:27.894 --> 00:23:29.515 - kinetic energy of the explosion, 637 00:23:30.375 --> 00:23:32.775 - and then 1% of that comes out as 638 00:23:32.775 --> 00:23:33.515 - the light. 639 00:23:34.134 --> 00:23:36.214 - And so bright as they are, the light 640 00:23:36.214 --> 00:23:37.894 - is sort of an afterthought, you know, point 641 00:23:37.894 --> 00:23:40.500 - o 1% of the actual explosion. It's really 642 00:23:40.500 --> 00:23:41.799 - a neutrino bomb, 643 00:23:42.339 --> 00:23:42.839 - and, 644 00:23:43.859 --> 00:23:46.119 - the kinetic energy is 1% of that. 645 00:23:46.580 --> 00:23:48.500 - And it sounds to me that there's a 646 00:23:48.500 --> 00:23:52.039 - lot of of nuclear physics going on here. 647 00:23:52.184 --> 00:23:54.924 - I mean, our our our supernovae, are they, 648 00:23:55.465 --> 00:23:56.205 - like a 649 00:23:56.545 --> 00:23:57.045 - a 650 00:23:57.384 --> 00:23:57.965 - a distant 651 00:23:58.585 --> 00:24:00.605 - laboratory that you can study 652 00:24:01.305 --> 00:24:03.005 - ideas of nuclear physics? 653 00:24:04.359 --> 00:24:07.019 - They they are the ultimate nuclear physics laboratory. 654 00:24:07.799 --> 00:24:09.500 - Everything reacts with everything. 655 00:24:10.119 --> 00:24:12.599 - The first three years of my research in 656 00:24:12.599 --> 00:24:13.880 - supernovae, I worked with, 657 00:24:14.519 --> 00:24:17.079 - Willie Fowler at Kellogg lab calculating the nuclear 658 00:24:17.079 --> 00:24:18.059 - reaction rates 659 00:24:18.424 --> 00:24:20.025 - for all of the things that go into 660 00:24:20.025 --> 00:24:22.025 - the nuclear synthesis that goes on these stars. 661 00:24:22.025 --> 00:24:23.565 - That's how I got started in 662 00:24:23.944 --> 00:24:25.404 - in my in my studies. 663 00:24:26.025 --> 00:24:28.105 - And you can have, as I mentioned, all 664 00:24:28.105 --> 00:24:30.904 - of the elements from from helium to to 665 00:24:30.904 --> 00:24:31.964 - nickel and beyond 666 00:24:32.549 --> 00:24:35.210 - interacting with neutrons, protons, and alpha particles. 667 00:24:35.590 --> 00:24:38.230 - There are literally tens of thousands of nuclear 668 00:24:38.230 --> 00:24:40.950 - reactions going on and keeping track of all 669 00:24:40.950 --> 00:24:42.650 - of them and seeing what comes out 670 00:24:42.950 --> 00:24:45.029 - is really a task for a big computer. 671 00:24:45.029 --> 00:24:48.335 - But yeah, they're type one a supernovae, especially, 672 00:24:48.335 --> 00:24:48.994 - are thermonuclear 673 00:24:49.295 --> 00:24:50.994 - bombs. They're entirely powered 674 00:24:51.375 --> 00:24:52.515 - by nuclear reactions. 675 00:24:52.974 --> 00:24:54.595 - In the type twos, 676 00:24:54.974 --> 00:24:57.694 - it's more, a neutrino event, as I said, 677 00:24:57.694 --> 00:24:59.375 - so there's a lot of particle physics as 678 00:24:59.375 --> 00:25:00.674 - well as nuclear physics. 679 00:25:01.009 --> 00:25:03.329 - But, yeah, just just about every nuclear reaction 680 00:25:03.329 --> 00:25:05.730 - you can think of happens in in these 681 00:25:05.730 --> 00:25:06.230 - explosions. 682 00:25:06.849 --> 00:25:08.230 - They are giant bombs. 683 00:25:09.009 --> 00:25:11.589 - So, Ken, thanks to work done by you, 684 00:25:11.730 --> 00:25:14.069 - Stan, and, of course, a lot of other 685 00:25:14.210 --> 00:25:14.710 - astrophysicists. 686 00:25:15.615 --> 00:25:16.595 - We know that, 687 00:25:17.134 --> 00:25:20.355 - some heavy elements are made during supernovae. 688 00:25:21.295 --> 00:25:24.115 - What elements are produced in type one a 689 00:25:24.335 --> 00:25:24.835 - supernovae, 690 00:25:25.454 --> 00:25:27.394 - and how are these elements produced? 691 00:25:28.859 --> 00:25:29.359 - Okay. 692 00:25:29.820 --> 00:25:30.880 - Yeah. As I said, 693 00:25:31.180 --> 00:25:31.920 - white dwarfs 694 00:25:32.380 --> 00:25:34.160 - are just cooling stars by itself 695 00:25:34.859 --> 00:25:36.400 - and doesn't explode. 696 00:25:36.779 --> 00:25:38.799 - But in close binary binaries, 697 00:25:39.180 --> 00:25:41.575 - we white dwarf had a companion star, 698 00:25:42.035 --> 00:25:44.674 - and that sent a lot of gas onto 699 00:25:44.674 --> 00:25:45.575 - the white dwarf. 700 00:25:46.035 --> 00:25:47.815 - So white dwarf mass grows 701 00:25:48.275 --> 00:25:49.174 - and becomes, 702 00:25:49.634 --> 00:25:52.215 - very much compact and becomes dense. 703 00:25:54.380 --> 00:25:56.240 - And, when there is a 704 00:25:57.179 --> 00:25:59.200 - they reach it the height of mass reaches 705 00:25:59.579 --> 00:26:01.179 - typically 1.4 706 00:26:01.179 --> 00:26:02.720 - so type for solar mass, 707 00:26:03.420 --> 00:26:04.559 - then the 708 00:26:06.325 --> 00:26:08.325 - the density in the in the central region 709 00:26:08.325 --> 00:26:09.305 - is high enough 710 00:26:09.765 --> 00:26:10.664 - for the carbon 711 00:26:11.125 --> 00:26:12.025 - to be ignited 712 00:26:12.805 --> 00:26:13.625 - by fusion. 713 00:26:14.565 --> 00:26:15.065 - And, 714 00:26:15.684 --> 00:26:17.785 - so because density is so high, 715 00:26:18.085 --> 00:26:19.705 - the white dough doesn't expand 716 00:26:21.000 --> 00:26:22.059 - because of the, 717 00:26:24.279 --> 00:26:26.700 - nuclear energy release. So nuclear energy 718 00:26:27.160 --> 00:26:29.019 - release just going to increase the temperature. 719 00:26:30.759 --> 00:26:31.259 - And 720 00:26:31.640 --> 00:26:32.140 - temperature 721 00:26:32.440 --> 00:26:33.420 - becomes so high 722 00:26:34.964 --> 00:26:36.505 - and not only carbon, 723 00:26:36.964 --> 00:26:38.585 - but also oxygen, magnesium, 724 00:26:39.204 --> 00:26:41.625 - and the silicon, and and eventually forming 725 00:26:42.005 --> 00:26:42.505 - the 726 00:26:43.204 --> 00:26:44.505 - nickel 56 727 00:26:45.845 --> 00:26:46.345 - and 728 00:26:46.644 --> 00:26:47.785 - at at almost 729 00:26:49.779 --> 00:26:52.359 - the 10 to the 10 degree in temperature. 730 00:26:54.500 --> 00:26:57.240 - And that nickel 56 731 00:26:57.380 --> 00:26:58.200 - is a radioactive 732 00:26:58.580 --> 00:26:59.799 - in this element. 733 00:27:00.259 --> 00:27:00.759 - And 734 00:27:02.740 --> 00:27:03.240 - so 735 00:27:03.625 --> 00:27:06.105 - that decays into cobalt 56, 736 00:27:06.105 --> 00:27:07.164 - which also unstable, 737 00:27:07.784 --> 00:27:08.284 - and 738 00:27:08.825 --> 00:27:11.404 - then it decays into iron 56, 739 00:27:11.464 --> 00:27:12.204 - most abundant 740 00:27:12.984 --> 00:27:13.484 - iron. 741 00:27:14.265 --> 00:27:14.585 - And, 742 00:27:15.304 --> 00:27:15.804 - so, 743 00:27:17.289 --> 00:27:17.789 - eventually, 744 00:27:18.170 --> 00:27:21.049 - type one s supernova produced lots of iron 745 00:27:21.049 --> 00:27:23.150 - because of the very high temperature 746 00:27:23.930 --> 00:27:25.470 - in the in the explosion 747 00:27:26.009 --> 00:27:28.809 - compared with more even higher than type two 748 00:27:28.809 --> 00:27:29.265 - supernova. 749 00:27:29.825 --> 00:27:30.325 - And 750 00:27:32.945 --> 00:27:33.845 - then the 751 00:27:35.664 --> 00:27:38.704 - the, the other thing is important is the 752 00:27:38.704 --> 00:27:39.204 - reductive 753 00:27:39.505 --> 00:27:40.005 - decays 754 00:27:40.464 --> 00:27:43.684 - of nickel 56 and cobalt 56. 755 00:27:44.440 --> 00:27:46.460 - They produce a lot of gamma rays 756 00:27:46.840 --> 00:27:48.619 - and the high energy X rays. 757 00:27:49.559 --> 00:27:50.380 - So that 758 00:27:50.920 --> 00:27:53.559 - provides a power for the light curve of 759 00:27:53.559 --> 00:27:54.220 - the supernovae. 760 00:27:54.840 --> 00:27:55.340 - So 761 00:27:55.799 --> 00:27:58.220 - the new in in terms of nuclear synthesis, 762 00:27:58.414 --> 00:28:00.974 - type one a supernova will produce lots of 763 00:28:00.974 --> 00:28:02.174 - iron 56 764 00:28:02.174 --> 00:28:02.674 - as 765 00:28:02.974 --> 00:28:06.515 - a decay product of the radioactive nickel 56 766 00:28:06.654 --> 00:28:10.414 - and produce some silicon sulfur, but which are 767 00:28:10.414 --> 00:28:13.315 - not much compared with the, massive explosion. 768 00:28:15.619 --> 00:28:16.339 - So the 769 00:28:16.740 --> 00:28:18.519 - in the evolution of the universe, 770 00:28:21.299 --> 00:28:23.240 - the the type one a is very special 771 00:28:23.299 --> 00:28:26.259 - role to increase the mass mass fraction of 772 00:28:26.259 --> 00:28:26.920 - the ion. 773 00:28:29.384 --> 00:28:31.304 - So so if we follow the chem so 774 00:28:31.304 --> 00:28:33.244 - called chemical evolution of galaxies, 775 00:28:34.505 --> 00:28:36.825 - we can know when type one is plasma 776 00:28:36.825 --> 00:28:38.365 - starts to increase ion 777 00:28:39.545 --> 00:28:40.605 - compared with others. 778 00:28:40.984 --> 00:28:43.109 - That is one thing. So, Ken, I I'm 779 00:28:43.109 --> 00:28:45.269 - sitting at a desk, and and the desk 780 00:28:45.269 --> 00:28:47.769 - has steel legs, which, of course, is mostly 781 00:28:47.830 --> 00:28:48.330 - iron. 782 00:28:48.789 --> 00:28:50.730 - What percentage of the iron 783 00:28:51.269 --> 00:28:53.430 - in that in those steel legs of my 784 00:28:53.430 --> 00:28:56.730 - desk do you think were made by type 785 00:28:56.789 --> 00:28:57.529 - one a 786 00:28:57.855 --> 00:29:00.095 - supernovae? Is it most of the iron, or 787 00:29:00.095 --> 00:29:02.095 - is it some of it? Could you can 788 00:29:02.095 --> 00:29:04.255 - you give a percentage? I think, this one 789 00:29:04.255 --> 00:29:06.674 - is about about 60% 790 00:29:07.454 --> 00:29:09.075 - of iron coming from 791 00:29:09.375 --> 00:29:10.589 - type one a, and, 792 00:29:11.529 --> 00:29:13.230 - this is coming from type twos. 793 00:29:13.690 --> 00:29:14.190 - Yeah. 794 00:29:15.690 --> 00:29:17.230 - Type twos also produce 795 00:29:17.849 --> 00:29:20.829 - the some iron and which is actually observed 796 00:29:21.450 --> 00:29:22.589 - in famous supernova 797 00:29:23.724 --> 00:29:26.304 - nineteen eighty seven a in Magellanic Cloud. 798 00:29:28.684 --> 00:29:29.585 - That is iron. 799 00:29:30.125 --> 00:29:32.304 - And what I wanted to say is that 800 00:29:32.684 --> 00:29:33.184 - the 801 00:29:34.204 --> 00:29:35.664 - the formation of the radioactive 802 00:29:36.044 --> 00:29:36.544 - nickel 803 00:29:37.009 --> 00:29:39.570 - to produce gamma rays are very important for 804 00:29:39.570 --> 00:29:40.150 - the brightness 805 00:29:41.009 --> 00:29:42.150 - of type one a. 806 00:29:42.610 --> 00:29:42.930 - And, 807 00:29:43.730 --> 00:29:45.509 - the white mass is very 808 00:29:46.130 --> 00:29:47.670 - relatively similar with each other. 809 00:29:48.130 --> 00:29:50.470 - It produced the mass of the 810 00:29:51.464 --> 00:29:53.244 - Nikkei 56 also similar. 811 00:29:53.944 --> 00:29:56.904 - So that makes the the brightness of type 812 00:29:56.904 --> 00:29:59.484 - one a also quite similar among them. 813 00:30:00.825 --> 00:30:03.384 - That makes the type one a a so 814 00:30:03.384 --> 00:30:03.884 - called 815 00:30:04.200 --> 00:30:05.019 - standard candle 816 00:30:06.359 --> 00:30:07.740 - for the distance measurement. 817 00:30:08.359 --> 00:30:10.299 - And that is related to the 818 00:30:10.599 --> 00:30:11.899 - the how 819 00:30:12.359 --> 00:30:14.539 - the type one a super has been used 820 00:30:15.000 --> 00:30:15.500 - to 821 00:30:16.119 --> 00:30:19.019 - to infer the distance of dark energy. 822 00:30:19.525 --> 00:30:21.204 - That's right, Ken. And that's something that we're 823 00:30:21.204 --> 00:30:22.184 - gonna talk about, 824 00:30:22.724 --> 00:30:24.904 - a bit later on in the podcast. 825 00:30:25.365 --> 00:30:26.325 - Stan, what about, 826 00:30:27.125 --> 00:30:27.625 - nucleosynthesis 827 00:30:28.404 --> 00:30:29.704 - in type two 828 00:30:30.164 --> 00:30:33.099 - supernovae? What what sort of elements are produced, 829 00:30:33.099 --> 00:30:34.619 - and and how do we know that these 830 00:30:34.619 --> 00:30:35.759 - elements are produced? 831 00:30:36.380 --> 00:30:38.539 - Most of the elements that we see in 832 00:30:38.539 --> 00:30:41.420 - in the everyday world are made in type 833 00:30:41.420 --> 00:30:42.160 - two supernovae. 834 00:30:43.180 --> 00:30:45.339 - Exceptions are hydrogen and helium, which are made 835 00:30:45.339 --> 00:30:46.320 - in the big bang. 836 00:30:46.875 --> 00:30:48.714 - And most of the iron group, but not 837 00:30:48.714 --> 00:30:50.234 - all of it, is made in type one 838 00:30:50.234 --> 00:30:52.015 - a supernova, the other kind. 839 00:30:52.394 --> 00:30:54.555 - But just about everything else, you know, the 840 00:30:55.035 --> 00:30:57.755 - most of the carbon, the oxygen, you know, 841 00:30:57.755 --> 00:30:59.434 - what we see in the ocean except for 842 00:30:59.434 --> 00:31:02.549 - the hydrogen, the mountains, our own bodies, it's 843 00:31:02.549 --> 00:31:04.250 - all made in supernovae. 844 00:31:05.509 --> 00:31:06.569 - How do we know? 845 00:31:07.190 --> 00:31:07.690 - Well, 846 00:31:08.069 --> 00:31:09.909 - several ways, but the most direct way is 847 00:31:09.909 --> 00:31:11.990 - looking at the remnants of supernovae and and 848 00:31:11.990 --> 00:31:12.889 - actually seeing, 849 00:31:13.190 --> 00:31:15.529 - as as in the Cas a supernova remnant, 850 00:31:16.964 --> 00:31:19.365 - the silicon and oxygen and and other heavy 851 00:31:19.365 --> 00:31:21.765 - elements that have been made there spewing out 852 00:31:21.765 --> 00:31:23.625 - at thousands of kilometers per second. 853 00:31:24.005 --> 00:31:26.244 - In supernova eighty seven a, we were able 854 00:31:26.244 --> 00:31:28.724 - to watch it expand and gradually uncover the 855 00:31:28.724 --> 00:31:29.464 - new elements, 856 00:31:29.869 --> 00:31:32.109 - And we actually detected the gamma rays coming 857 00:31:32.109 --> 00:31:33.009 - from the decay 858 00:31:33.549 --> 00:31:36.750 - of radioactive nickel 56 in supernova eighty seven 859 00:31:36.750 --> 00:31:37.250 - a. 860 00:31:37.710 --> 00:31:40.750 - Now that specific isotope is very interesting because 861 00:31:40.750 --> 00:31:42.210 - it it decays to iron. 862 00:31:42.765 --> 00:31:44.785 - And all of the iron in our bodies 863 00:31:44.924 --> 00:31:45.664 - and everywhere 864 00:31:46.125 --> 00:31:48.945 - has been created first as nickel 56. 865 00:31:49.404 --> 00:31:51.244 - So as I as I mentioned, we're not 866 00:31:51.244 --> 00:31:54.045 - just stardust, we are fallout. And in fact, 867 00:31:54.045 --> 00:31:56.705 - part of it is is formally radioactive fallout. 868 00:31:57.750 --> 00:31:59.430 - And and I think it's right to say 869 00:31:59.430 --> 00:31:59.750 - that, 870 00:32:00.470 --> 00:32:00.970 - some 871 00:32:01.349 --> 00:32:03.049 - heavy heavier elements 872 00:32:03.589 --> 00:32:04.490 - like gold, 873 00:32:05.349 --> 00:32:07.210 - also have a a connection 874 00:32:07.910 --> 00:32:09.210 - to type two 875 00:32:10.335 --> 00:32:10.835 - supernovae 876 00:32:11.134 --> 00:32:14.595 - because they're made in neutron stars or merging 877 00:32:14.654 --> 00:32:17.295 - neutron stars. Is that right? So there's a 878 00:32:17.295 --> 00:32:19.934 - connection there as well, isn't there? Yes. I 879 00:32:19.934 --> 00:32:21.775 - I kind of glossed over that by saying 880 00:32:21.775 --> 00:32:24.115 - the common elements of existence because 881 00:32:24.509 --> 00:32:26.130 - gold is is somewhat uncommon 882 00:32:26.910 --> 00:32:29.070 - as is platinum and so on and has 883 00:32:29.070 --> 00:32:30.750 - has has been in the news a lot 884 00:32:30.750 --> 00:32:31.250 - recently. 885 00:32:31.789 --> 00:32:34.029 - We now believe that most of those very 886 00:32:34.029 --> 00:32:35.570 - heavy elements are made, 887 00:32:36.349 --> 00:32:38.910 - by something called the r process in merging 888 00:32:38.910 --> 00:32:39.970 - neutron stars. 889 00:32:40.454 --> 00:32:42.615 - But supernovae still play a role because the 890 00:32:42.615 --> 00:32:45.654 - neutron stars came from from supernovae to start 891 00:32:45.654 --> 00:32:48.615 - with, so perhaps I wasn't stretching things too 892 00:32:48.615 --> 00:32:50.934 - much. It's just there's this other step that 893 00:32:50.934 --> 00:32:52.855 - you have to have two supernovae close to 894 00:32:52.855 --> 00:32:55.339 - each other that leave two neutron stars that 895 00:32:55.339 --> 00:32:58.539 - gradually spiral into each other and eject very 896 00:32:58.539 --> 00:33:01.359 - neutron rich matter that partially becomes gold. 897 00:33:01.819 --> 00:33:04.460 - Can you you sort of hinted earlier that 898 00:33:04.460 --> 00:33:05.919 - type one a supernovae 899 00:33:06.484 --> 00:33:08.105 - play an important role 900 00:33:08.484 --> 00:33:09.545 - in our understanding 901 00:33:10.005 --> 00:33:12.244 - of the expansion of the universe. Can you 902 00:33:12.244 --> 00:33:12.744 - explain 903 00:33:13.205 --> 00:33:13.705 - why? 904 00:33:14.085 --> 00:33:14.965 - Why are these, 905 00:33:15.445 --> 00:33:18.184 - objects so important to, cosmologists? 906 00:33:20.069 --> 00:33:20.569 - Because, 907 00:33:22.069 --> 00:33:24.250 - it's important to know the distance 908 00:33:25.190 --> 00:33:25.690 - or 909 00:33:26.150 --> 00:33:27.529 - the size of the universe 910 00:33:27.990 --> 00:33:29.369 - as a function of time 911 00:33:29.670 --> 00:33:31.849 - to understand the expansion of the universe. 912 00:33:32.710 --> 00:33:34.250 - To know the distance, 913 00:33:35.555 --> 00:33:36.535 - we should have 914 00:33:36.994 --> 00:33:39.674 - a so called standard candles, and that is 915 00:33:39.875 --> 00:33:41.654 - the luminosity is the same. 916 00:33:42.035 --> 00:33:42.355 - And, 917 00:33:43.075 --> 00:33:45.174 - if the standard candle is far 918 00:33:45.954 --> 00:33:49.259 - from us, it's faint, and it's closer, it's 919 00:33:49.420 --> 00:33:49.920 - brighter. 920 00:33:50.539 --> 00:33:53.579 - And, so measurement of the brightness of the 921 00:33:53.579 --> 00:33:56.880 - standard candles is important to know the distance 922 00:33:57.019 --> 00:33:59.759 - to the the distance of the galaxies which 923 00:34:00.059 --> 00:34:02.160 - the those standard candles are included. 924 00:34:02.965 --> 00:34:03.465 - And, 925 00:34:03.924 --> 00:34:04.825 - as I said, 926 00:34:05.684 --> 00:34:06.985 - the type one a supernova 927 00:34:07.445 --> 00:34:09.605 - is exploding white dwarfs, so then the mass 928 00:34:09.605 --> 00:34:10.664 - of the white dwarf 929 00:34:11.005 --> 00:34:11.505 - is 930 00:34:11.844 --> 00:34:14.184 - basically very similar with each other. 931 00:34:14.644 --> 00:34:15.144 - And, 932 00:34:15.765 --> 00:34:16.739 - that means that 933 00:34:17.460 --> 00:34:20.980 - produced amount of nickel 50 radioactive nickel 56 934 00:34:20.980 --> 00:34:22.039 - is also similar. 935 00:34:22.820 --> 00:34:24.440 - So that means the brightness 936 00:34:25.380 --> 00:34:28.179 - or some some even some variation, but also 937 00:34:28.179 --> 00:34:28.755 - quite similar. 938 00:34:29.714 --> 00:34:32.214 - Similar. So with with some corrections, 939 00:34:32.914 --> 00:34:33.894 - we can use 940 00:34:35.154 --> 00:34:35.734 - the observed 941 00:34:36.194 --> 00:34:36.694 - luminosity 942 00:34:36.994 --> 00:34:39.014 - brightness of type one and supernovae 943 00:34:39.554 --> 00:34:40.054 - as 944 00:34:40.434 --> 00:34:40.594 - the, 945 00:34:41.315 --> 00:34:42.054 - the constant. 946 00:34:42.674 --> 00:34:43.829 - And so 947 00:34:45.250 --> 00:34:46.309 - if we 948 00:34:46.690 --> 00:34:47.670 - so the people 949 00:34:48.289 --> 00:34:50.069 - using satellite to measure 950 00:34:50.609 --> 00:34:53.190 - the brightness of the many type one supernovae. 951 00:34:53.969 --> 00:34:54.369 - And, 952 00:34:55.089 --> 00:34:56.309 - so distant supernovae 953 00:34:56.609 --> 00:34:59.195 - type one supernovae is faint and the nearby 954 00:34:59.974 --> 00:35:00.555 - is brighter. 955 00:35:01.015 --> 00:35:01.755 - So if, 956 00:35:02.454 --> 00:35:04.875 - because the universe is now expanding, 957 00:35:05.735 --> 00:35:06.235 - the 958 00:35:07.735 --> 00:35:08.235 - the 959 00:35:09.335 --> 00:35:10.555 - in the old days, 960 00:35:11.414 --> 00:35:12.555 - the type one is super 961 00:35:13.380 --> 00:35:15.319 - at the at far far distance, 962 00:35:16.099 --> 00:35:18.839 - the is observed as the faint ones, 963 00:35:19.619 --> 00:35:21.639 - and the recent one is is 964 00:35:21.940 --> 00:35:23.400 - observed as bright one. 965 00:35:23.859 --> 00:35:24.359 - And 966 00:35:26.260 --> 00:35:26.659 - and, 967 00:35:28.339 --> 00:35:28.664 - if 968 00:35:29.625 --> 00:35:31.405 - the expansion of the universe 969 00:35:32.664 --> 00:35:33.804 - is being accelerated, 970 00:35:35.065 --> 00:35:38.445 - which we have a conclusion, but being accelerated, 971 00:35:39.385 --> 00:35:40.204 - that means, 972 00:35:40.744 --> 00:35:41.644 - in the past, 973 00:35:42.905 --> 00:35:43.909 - it's the 974 00:35:44.210 --> 00:35:44.710 - expansion 975 00:35:45.250 --> 00:35:46.069 - is slower 976 00:35:47.010 --> 00:35:48.150 - than the present. 977 00:35:49.809 --> 00:35:52.609 - From the past, it's slower and then being 978 00:35:52.609 --> 00:35:55.750 - accelerated to the current speed and then further 979 00:35:55.969 --> 00:35:58.304 - increase in exponential speed later. 980 00:35:59.425 --> 00:35:59.925 - And, 981 00:36:00.385 --> 00:36:01.364 - so that means, 982 00:36:01.984 --> 00:36:03.364 - the at the same time, 983 00:36:03.744 --> 00:36:06.244 - measured by the red circle redshift, 984 00:36:07.025 --> 00:36:07.525 - the 985 00:36:09.425 --> 00:36:10.724 - the if 986 00:36:11.969 --> 00:36:13.429 - if we compare the observed 987 00:36:15.730 --> 00:36:16.949 - supernova brightness 988 00:36:17.890 --> 00:36:18.390 - with 989 00:36:18.929 --> 00:36:19.750 - the prediction 990 00:36:21.329 --> 00:36:23.510 - without any acceleration or decelerations, 991 00:36:27.494 --> 00:36:28.474 - We know the 992 00:36:29.574 --> 00:36:29.974 - the, 993 00:36:31.335 --> 00:36:33.675 - if, okay, if the observed supernovae 994 00:36:34.695 --> 00:36:35.515 - is fainter 995 00:36:36.135 --> 00:36:36.635 - than 996 00:36:36.940 --> 00:36:40.159 - the predicted for the non accelerating universe, 997 00:36:41.099 --> 00:36:41.599 - then 998 00:36:45.260 --> 00:36:48.380 - the accelerate the expansion of the universe is 999 00:36:48.380 --> 00:36:49.199 - being accelerated. 1000 00:36:50.045 --> 00:36:51.905 - In the past, it's through expansion. 1001 00:36:53.325 --> 00:36:53.825 - So 1002 00:36:54.605 --> 00:36:55.585 - in that way, 1003 00:36:56.845 --> 00:36:58.144 - the standard candles 1004 00:36:58.765 --> 00:36:59.585 - can be used 1005 00:37:01.244 --> 00:37:02.545 - to decide if 1006 00:37:03.739 --> 00:37:05.440 - the universe is being accelerated 1007 00:37:05.900 --> 00:37:06.559 - or even 1008 00:37:08.300 --> 00:37:08.960 - or decelerating 1009 00:37:09.659 --> 00:37:11.359 - compared with the, nothing. 1010 00:37:13.339 --> 00:37:15.599 - Just simple ex the expansion. 1011 00:37:16.364 --> 00:37:16.864 - So 1012 00:37:17.644 --> 00:37:19.184 - the observed group, 1013 00:37:20.125 --> 00:37:21.905 - the two groups measured 1014 00:37:22.445 --> 00:37:24.784 - the distant type one supernova brightness 1015 00:37:25.565 --> 00:37:26.385 - and found 1016 00:37:26.925 --> 00:37:29.664 - at so called redshift point 5.5, 1017 00:37:30.204 --> 00:37:32.289 - the the super observable supernovae 1018 00:37:32.590 --> 00:37:34.050 - is fainter significantly 1019 00:37:34.429 --> 00:37:36.289 - fainter than the predicted 1020 00:37:36.829 --> 00:37:38.110 - by the the, 1021 00:37:38.670 --> 00:37:39.489 - non accelerating 1022 00:37:40.429 --> 00:37:41.730 - expansion being universe. 1023 00:37:42.510 --> 00:37:44.030 - So that faint means, 1024 00:37:44.694 --> 00:37:47.034 - the in the past, expansion is slower 1025 00:37:47.414 --> 00:37:50.135 - than the current one. And so the current 1026 00:37:50.135 --> 00:37:52.394 - rate, the universe is being accelerated. 1027 00:37:53.494 --> 00:37:55.194 - And that, of course, is a big surprise. 1028 00:37:55.655 --> 00:37:58.474 - Yes. Right. Because, people believe 1029 00:37:58.929 --> 00:38:00.309 - the universe has a matter. 1030 00:38:00.929 --> 00:38:02.309 - So it's being even 1031 00:38:02.690 --> 00:38:03.190 - decelerated 1032 00:38:03.730 --> 00:38:05.670 - by the by its matter itself. 1033 00:38:06.369 --> 00:38:06.849 - And, 1034 00:38:09.890 --> 00:38:10.469 - so there 1035 00:38:11.170 --> 00:38:13.269 - is no clear idea of what 1036 00:38:13.664 --> 00:38:14.164 - is 1037 00:38:16.065 --> 00:38:17.285 - the causing expansion 1038 00:38:18.704 --> 00:38:19.525 - of the universe. 1039 00:38:20.465 --> 00:38:23.025 - So we are calling that that is dark 1040 00:38:23.025 --> 00:38:24.324 - energy. Dark energy 1041 00:38:25.425 --> 00:38:26.965 - is being, decelerated 1042 00:38:27.590 --> 00:38:28.250 - the universe. 1043 00:38:28.630 --> 00:38:31.050 - So in a sense, supernovae are responsible 1044 00:38:31.349 --> 00:38:31.849 - for, 1045 00:38:32.469 --> 00:38:34.329 - perhaps one of the most profound 1046 00:38:35.429 --> 00:38:35.929 - discoveries 1047 00:38:36.389 --> 00:38:37.050 - in cosmology 1048 00:38:38.150 --> 00:38:38.889 - in the last, 1049 00:38:39.190 --> 00:38:40.650 - well, fifty years or 1050 00:38:40.994 --> 00:38:43.315 - what what whatever. Yeah. So it I mean, 1051 00:38:43.315 --> 00:38:45.875 - it just goes to show how important these 1052 00:38:45.875 --> 00:38:46.855 - objects are, 1053 00:38:47.795 --> 00:38:50.454 - to astronomy and, our understanding 1054 00:38:51.154 --> 00:38:52.054 - of the universe. 1055 00:38:52.755 --> 00:38:55.474 - So, Stan, what are you most excited about 1056 00:38:55.474 --> 00:38:56.454 - in current 1057 00:38:56.909 --> 00:38:57.409 - supernovae 1058 00:38:57.710 --> 00:38:58.210 - research? 1059 00:38:59.309 --> 00:39:01.549 - Well, there's so many exciting things coming up, 1060 00:39:01.549 --> 00:39:03.309 - but the the first that comes to mind 1061 00:39:03.309 --> 00:39:03.789 - is the, 1062 00:39:04.589 --> 00:39:05.650 - Rubin Observatory 1063 00:39:06.030 --> 00:39:08.609 - legacy survey of space and time, which is 1064 00:39:08.945 --> 00:39:11.425 - going to discover, they say, about a quarter 1065 00:39:11.425 --> 00:39:14.005 - of a million supernovae per year for 1066 00:39:14.625 --> 00:39:16.164 - maybe the next ten years. 1067 00:39:16.864 --> 00:39:19.545 - That's that's a huge number, obviously, and and 1068 00:39:19.545 --> 00:39:21.425 - a lot of it'll just be more of 1069 00:39:21.425 --> 00:39:23.909 - the same, which is interesting to people like 1070 00:39:23.909 --> 00:39:25.690 - me. But the most interesting cases 1071 00:39:26.309 --> 00:39:28.809 - will be the outliers with millions of supernovae. 1072 00:39:28.869 --> 00:39:30.250 - There'll be thousands of 1073 00:39:30.550 --> 00:39:31.050 - unusual 1074 00:39:31.510 --> 00:39:33.609 - super luminous supernovae, supernovae 1075 00:39:34.150 --> 00:39:35.929 - connected with gamma ray bursts, 1076 00:39:36.394 --> 00:39:39.355 - supernovae with strange stars and progenitors, and so 1077 00:39:39.355 --> 00:39:41.135 - on. It's enough to last 1078 00:39:42.155 --> 00:39:44.795 - at least one lifetime just analyzing that, and 1079 00:39:44.795 --> 00:39:46.574 - so I'm really looking forward to that. 1080 00:39:47.514 --> 00:39:50.795 - Another telescope coming online is is the James 1081 00:39:50.795 --> 00:39:51.695 - Webb Telescope, 1082 00:39:52.630 --> 00:39:54.230 - which is very good good at looking in 1083 00:39:54.230 --> 00:39:55.690 - the far infrared and seeing 1084 00:39:56.469 --> 00:39:59.690 - high redshift galaxies and measuring abundances there. 1085 00:40:00.150 --> 00:40:01.750 - And it's very exciting to think that we 1086 00:40:01.750 --> 00:40:03.449 - can actually look back in time 1087 00:40:03.829 --> 00:40:05.829 - and see when the first elements were being 1088 00:40:05.829 --> 00:40:08.284 - made and the first stars, the first supernovae. 1089 00:40:08.905 --> 00:40:11.464 - And so that's extremely exciting. I might I 1090 00:40:11.464 --> 00:40:13.405 - might add parenthetically, this is 1091 00:40:14.025 --> 00:40:16.184 - partially the reason that Ken and I got 1092 00:40:16.184 --> 00:40:17.484 - the the Shaw prize, 1093 00:40:18.264 --> 00:40:19.484 - was our quantitative 1094 00:40:19.784 --> 00:40:20.764 - theories of nucleosynthesis. 1095 00:40:21.900 --> 00:40:24.699 - For seventy years, we've we've known that, that 1096 00:40:24.699 --> 00:40:27.819 - the elements are probably made in stars and 1097 00:40:27.819 --> 00:40:28.319 - supernovae, 1098 00:40:28.940 --> 00:40:30.719 - but now that's an absolute certainty. 1099 00:40:31.339 --> 00:40:31.739 - And, 1100 00:40:32.299 --> 00:40:34.619 - now it's become a quantitative field, and so 1101 00:40:34.619 --> 00:40:36.319 - what we've done is to calculate 1102 00:40:37.434 --> 00:40:40.474 - models for stars of different masses, supernovae of 1103 00:40:40.474 --> 00:40:42.174 - different types, of all types, 1104 00:40:42.635 --> 00:40:44.074 - and to add it all up and get 1105 00:40:44.074 --> 00:40:46.974 - a history of the abundances in our galaxy, 1106 00:40:47.034 --> 00:40:49.914 - the abundances in the sun, the abundances in 1107 00:40:49.914 --> 00:40:50.655 - other galaxies. 1108 00:40:51.210 --> 00:40:53.050 - So everywhere you can make a new abundance 1109 00:40:53.050 --> 00:40:53.550 - determination, 1110 00:40:53.929 --> 00:40:55.710 - we're we're very interested in that. 1111 00:40:56.809 --> 00:40:59.469 - We're still waiting for the galactic supernova. 1112 00:41:00.010 --> 00:41:02.570 - Now 87 a was close, but it's a 1113 00:41:02.570 --> 00:41:03.690 - 160,000 1114 00:41:03.690 --> 00:41:06.429 - light years away in in the Magellanic Cloud. 1115 00:41:06.844 --> 00:41:09.025 - Supposedly, there's one every fifty years. 1116 00:41:09.404 --> 00:41:11.724 - Most of them, we don't see with our 1117 00:41:11.724 --> 00:41:12.944 - naked eye because 1118 00:41:13.324 --> 00:41:15.164 - they're in the disc of the galaxy and 1119 00:41:15.164 --> 00:41:16.464 - the dust and the gas 1120 00:41:16.844 --> 00:41:18.684 - makes it hard even for a supernova to 1121 00:41:18.684 --> 00:41:20.385 - be seen so far away. 1122 00:41:21.300 --> 00:41:24.099 - But with neutrino observatories that are now online 1123 00:41:24.099 --> 00:41:25.719 - and with gravitational radiation 1124 00:41:26.019 --> 00:41:28.820 - observatories that are now online and infrared and 1125 00:41:28.820 --> 00:41:30.840 - radio, we we would now see a supernova 1126 00:41:30.900 --> 00:41:32.119 - anywhere in the galaxy. 1127 00:41:32.660 --> 00:41:35.380 - And it happens every fifty years statistically and 1128 00:41:35.380 --> 00:41:36.440 - it hasn't happened 1129 00:41:36.924 --> 00:41:37.984 - in a long time. 1130 00:41:38.444 --> 00:41:40.924 - And so any day now or any decade 1131 00:41:40.924 --> 00:41:42.625 - now or any century now, 1132 00:41:43.164 --> 00:41:45.565 - we're gonna have the next supernova and that 1133 00:41:45.565 --> 00:41:48.204 - will be exciting. We'll study it close-up. We'll 1134 00:41:48.204 --> 00:41:49.184 - study the neutrinos 1135 00:41:50.070 --> 00:41:52.070 - carefully and finally learn you know, you can't 1136 00:41:52.070 --> 00:41:53.590 - see what's going on in the middle of 1137 00:41:53.590 --> 00:41:54.809 - this collapsing star. 1138 00:41:55.110 --> 00:41:56.969 - Except with neutrinos, you can. 1139 00:41:57.269 --> 00:41:59.269 - And so maybe we can uncover a little 1140 00:41:59.269 --> 00:42:01.430 - more about what what the central engine is 1141 00:42:01.430 --> 00:42:02.885 - going to do there. 1142 00:42:03.265 --> 00:42:06.244 - On computers, they also get bigger and amazing 1143 00:42:06.704 --> 00:42:07.445 - every year. 1144 00:42:08.465 --> 00:42:09.364 - And simulations 1145 00:42:09.664 --> 00:42:12.965 - in three dimensions with detailed neutrino transport 1146 00:42:13.744 --> 00:42:15.824 - are starting to become available, but they're still 1147 00:42:15.824 --> 00:42:16.565 - pretty primitive. 1148 00:42:17.059 --> 00:42:17.960 - And after, 1149 00:42:18.260 --> 00:42:19.400 - what's it been, 1150 00:42:19.780 --> 00:42:22.359 - sixty years since we first had the 1151 00:42:22.659 --> 00:42:25.400 - proposed model by Colgate of the neutrino transport 1152 00:42:25.539 --> 00:42:26.039 - supernova, 1153 00:42:26.340 --> 00:42:27.239 - which I described, 1154 00:42:27.859 --> 00:42:28.920 - we still haven't 1155 00:42:29.315 --> 00:42:31.474 - all in the community agreed on just which 1156 00:42:31.474 --> 00:42:33.095 - stars blow up and just how 1157 00:42:33.555 --> 00:42:36.055 - because it's just such a hard three-dimensional, 1158 00:42:36.595 --> 00:42:37.494 - maybe magnetohydrodynamic 1159 00:42:38.355 --> 00:42:38.855 - rotational 1160 00:42:39.315 --> 00:42:41.095 - neutrino transport problem. 1161 00:42:41.650 --> 00:42:43.809 - But the computers and the codes are getting 1162 00:42:43.809 --> 00:42:45.489 - where they can do that, and so I'm 1163 00:42:45.489 --> 00:42:46.710 - excited about that. 1164 00:42:47.809 --> 00:42:50.210 - I'm excited about gamma ray bursts. Now this 1165 00:42:50.210 --> 00:42:52.449 - is something we didn't mention much, but they're 1166 00:42:52.449 --> 00:42:54.150 - an unusual kind of supernova. 1167 00:42:54.914 --> 00:42:57.554 - These are really the brightest explosions in the 1168 00:42:57.554 --> 00:42:58.614 - universe. They 1169 00:42:58.914 --> 00:43:01.494 - they emit as much light in our direction 1170 00:43:02.114 --> 00:43:04.035 - in in a few seconds as the sun 1171 00:43:04.035 --> 00:43:06.035 - will put out in its ten billion year 1172 00:43:06.035 --> 00:43:08.135 - lifetime multiplied by a 100. 1173 00:43:08.799 --> 00:43:09.299 - And 1174 00:43:09.679 --> 00:43:11.839 - I'm I'm excited about them partly because I 1175 00:43:11.839 --> 00:43:14.239 - proposed the model for how they work, which 1176 00:43:14.239 --> 00:43:17.059 - is that when one of these supernova collapses 1177 00:43:17.199 --> 00:43:19.440 - the core, that instead of making a neutron 1178 00:43:19.440 --> 00:43:20.960 - star, it makes a black hole and the 1179 00:43:20.960 --> 00:43:22.579 - rest of the star falls in 1180 00:43:22.925 --> 00:43:24.684 - and forms a disk around the black hole 1181 00:43:24.684 --> 00:43:26.385 - and makes a little miniature quasar 1182 00:43:26.844 --> 00:43:28.605 - which launches jets. And if we're in the 1183 00:43:28.605 --> 00:43:30.605 - jet, we see the gamma ray burst. Well, 1184 00:43:30.605 --> 00:43:32.525 - it's it's a nice story and in fact, 1185 00:43:32.525 --> 00:43:34.525 - I think the community largely believes it, but 1186 00:43:34.525 --> 00:43:37.025 - it's still to be completely verified. 1187 00:43:37.969 --> 00:43:41.089 - There are other possibilities all involving massive stars, 1188 00:43:41.089 --> 00:43:44.150 - but I'd like to see some confirmation, perhaps 1189 00:43:44.210 --> 00:43:45.589 - observational of that. 1190 00:43:46.049 --> 00:43:48.369 - We haven't seen the actual progenitors of type 1191 00:43:48.369 --> 00:43:49.750 - one a supernova, 1192 00:43:50.625 --> 00:43:52.864 - And we'd really like to, you know, get 1193 00:43:52.864 --> 00:43:54.644 - a handle, if not see them directly, 1194 00:43:55.105 --> 00:43:57.605 - see the companions or see evidence that this 1195 00:43:57.824 --> 00:44:00.065 - nice fiction that we've built that explains so 1196 00:44:00.065 --> 00:44:00.565 - much 1197 00:44:00.864 --> 00:44:02.644 - of accreting white dwarfs 1198 00:44:02.945 --> 00:44:03.765 - really is 1199 00:44:04.144 --> 00:44:05.445 - what's going on. 1200 00:44:06.059 --> 00:44:06.719 - And finally, 1201 00:44:07.180 --> 00:44:08.000 - most exciting 1202 00:44:08.460 --> 00:44:11.599 - today is what LIGO, Virgo, Kogra are doing, 1203 00:44:11.900 --> 00:44:14.559 - watching merging black holes and studying the gravitational 1204 00:44:14.780 --> 00:44:15.280 - radiation. 1205 00:44:15.820 --> 00:44:18.539 - They've seen 300 black holes merge so far, 1206 00:44:18.539 --> 00:44:20.904 - but they're gonna see many, many more. And 1207 00:44:20.904 --> 00:44:22.505 - so we'll be able to map out the 1208 00:44:22.505 --> 00:44:23.005 - distribution 1209 00:44:23.704 --> 00:44:26.025 - of the black hole remnants that supernova leave 1210 00:44:26.025 --> 00:44:26.525 - behind, 1211 00:44:26.824 --> 00:44:28.664 - which is fascinating in itself, but also a 1212 00:44:28.664 --> 00:44:30.585 - powerful constraint on what blows up and what 1213 00:44:30.585 --> 00:44:33.144 - doesn't. And and, Ken, what are you most 1214 00:44:33.144 --> 00:44:35.164 - excited about in current 1215 00:44:35.519 --> 00:44:36.739 - supernovae research? 1216 00:44:37.280 --> 00:44:40.099 - I was very much excited with the observation 1217 00:44:40.320 --> 00:44:41.780 - of the type the supernova 1218 00:44:42.480 --> 00:44:44.019 - '19 80 '7 a, 1219 00:44:44.400 --> 00:44:45.539 - imaginary cloud, 1220 00:44:46.079 --> 00:44:49.360 - because, the our colleagues in University of Tokyo 1221 00:44:49.360 --> 00:44:50.340 - observed neutrinos 1222 00:44:51.144 --> 00:44:54.344 - from that event, and we we are very 1223 00:44:54.344 --> 00:44:55.484 - close to them. 1224 00:44:56.025 --> 00:44:57.244 - And, but theoretically, 1225 00:44:58.105 --> 00:44:58.264 - the 1226 00:44:59.625 --> 00:45:01.724 - what I was very much excited is 1227 00:45:02.505 --> 00:45:04.969 - we have I made a kind of prediction 1228 00:45:05.269 --> 00:45:07.590 - of the model of type one a super 1229 00:45:07.590 --> 00:45:09.769 - and b as a exploding white dwarf 1230 00:45:10.389 --> 00:45:12.010 - and calculated the 1231 00:45:13.110 --> 00:45:13.929 - the light carbon 1232 00:45:14.469 --> 00:45:14.969 - spectra. 1233 00:45:15.750 --> 00:45:16.070 - But, 1234 00:45:16.625 --> 00:45:19.264 - in Japan, we didn't at that time have 1235 00:45:19.264 --> 00:45:20.885 - a observer observed groups 1236 00:45:21.824 --> 00:45:22.405 - of supernovae. 1237 00:45:23.105 --> 00:45:25.424 - So we have no way to check. Then 1238 00:45:25.424 --> 00:45:25.924 - I 1239 00:45:26.304 --> 00:45:29.605 - I went to US and attended conference, and 1240 00:45:31.340 --> 00:45:33.360 - then the, several people 1241 00:45:33.820 --> 00:45:34.640 - told me, 1242 00:45:35.739 --> 00:45:36.559 - your model 1243 00:45:37.099 --> 00:45:40.079 - prediction is very much fit to the observed 1244 00:45:40.380 --> 00:45:41.360 - type one super. 1245 00:45:42.219 --> 00:45:42.719 - Actually, 1246 00:45:43.019 --> 00:45:45.994 - the comparison my with my models with all 1247 00:45:45.994 --> 00:45:46.574 - the observations 1248 00:45:47.434 --> 00:45:49.755 - are in very good agreement, and that was 1249 00:45:49.755 --> 00:45:52.094 - a big very big surprise and exciting 1250 00:45:53.034 --> 00:45:55.534 - how my theoretical model is confirmed. 1251 00:45:56.519 --> 00:45:59.320 - I didn't expect my storage model will be 1252 00:45:59.320 --> 00:46:01.739 - confirmed by the observational universe. 1253 00:46:03.559 --> 00:46:05.960 - So but in US, they did. So it's 1254 00:46:06.199 --> 00:46:08.059 - that that is very much exciting. 1255 00:46:16.324 --> 00:46:17.864 - That was Ken Namoto 1256 00:46:18.244 --> 00:46:19.704 - and Stan Woosley 1257 00:46:20.005 --> 00:46:22.264 - who shared the 2026 1258 00:46:22.710 --> 00:46:24.329 - Shaw prize in astronomy. 1259 00:46:25.109 --> 00:46:27.530 - Thanks to both of them for a fascinating 1260 00:46:27.750 --> 00:46:28.250 - discussion 1261 00:46:28.630 --> 00:46:29.609 - about supernovae. 1262 00:46:30.710 --> 00:46:33.210 - And thanks to the Shaw prize foundation 1263 00:46:33.670 --> 00:46:35.449 - for sponsoring this episode. 1264 00:46:36.264 --> 00:46:38.284 - The Shaw Prize is an international 1265 00:46:38.585 --> 00:46:40.284 - prize based in Hong Kong. 1266 00:46:40.905 --> 00:46:44.525 - Currently, it consists of three annual awards, 1267 00:46:45.065 --> 00:46:46.284 - the prize in astronomy, 1268 00:46:46.824 --> 00:46:49.405 - the prize in life science and medicine, 1269 00:46:50.010 --> 00:46:52.750 - and the prize in mathematical sciences. 1270 00:46:53.610 --> 00:46:55.230 - In 2027, 1271 00:46:55.610 --> 00:46:57.550 - a fourth prize will be awarded 1272 00:46:57.929 --> 00:47:00.110 - for work in computer science. 1273 00:47:00.969 --> 00:47:02.829 - Each prize carries a monetary 1274 00:47:03.130 --> 00:47:05.614 - award of 1,200,000 1275 00:47:06.074 --> 00:47:06.974 - US dollars. 1276 00:47:07.675 --> 00:47:08.974 - The prize was established 1277 00:47:09.355 --> 00:47:10.655 - by Runrun Shaw, 1278 00:47:11.035 --> 00:47:13.054 - a media mogul and philanthropist. 1279 00:47:14.074 --> 00:47:17.215 - It was first awarded in 2004, 1280 00:47:17.434 --> 00:47:18.655 - and since then, 1281 00:47:18.980 --> 00:47:20.579 - 121 1282 00:47:20.579 --> 00:47:21.079 - prizes 1283 00:47:21.460 --> 00:47:23.319 - have been given to individuals 1284 00:47:23.940 --> 00:47:25.239 - from across the world. 1285 00:47:26.019 --> 00:47:27.940 - I'm afraid that's all the time we have 1286 00:47:27.940 --> 00:47:29.079 - for this week's podcast. 1287 00:47:29.460 --> 00:47:32.659 - I'm Hamish Johnston, and our producer is Fred 1288 00:47:32.659 --> 00:47:33.159 - Isles. 1289 00:47:33.735 --> 00:47:35.994 - The music that you heard in this episode 1290 00:47:36.215 --> 00:47:38.474 - is called one three seven, 1291 00:47:38.855 --> 00:47:40.875 - and it was composed and performed 1292 00:47:41.175 --> 00:47:42.075 - by the physicist 1293 00:47:42.695 --> 00:47:43.675 - Philip Moriarty. 1294 00:47:44.615 --> 00:47:46.469 - We'll be back again next week.