1 00:00:15,356 --> 00:00:23,236 Speaker 1: Pushkin from Pushkin Industries. This is Deep Background, the show 2 00:00:23,316 --> 00:00:26,276 Speaker 1: where we explored the stories behind the stories in the news. 3 00:00:26,716 --> 00:00:33,476 Speaker 1: I'm Noah Feldman. The world has recently been gripped by 4 00:00:33,556 --> 00:00:39,716 Speaker 1: the extraordinary and extraordinarily beautiful image of a black hole, 5 00:00:40,276 --> 00:00:44,676 Speaker 1: a thing which we know allows no information or light 6 00:00:44,756 --> 00:00:47,796 Speaker 1: to escape, and of which we therefore, strictly speaking, shouldn't 7 00:00:47,796 --> 00:00:51,036 Speaker 1: have an image at all to make sense of this. 8 00:00:51,516 --> 00:00:54,116 Speaker 1: At the level of logic, at the level of physics, 9 00:00:54,156 --> 00:00:57,116 Speaker 1: and at the level of deeper meaning, we're thrilled to 10 00:00:57,156 --> 00:01:00,836 Speaker 1: have with us today. Andy Strominger one of the leading 11 00:01:00,876 --> 00:01:04,836 Speaker 1: theoretical physicists in the world who's made fundamental contributions to 12 00:01:04,916 --> 00:01:08,396 Speaker 1: quantum gravity theory, to string theory, and has also worked 13 00:01:08,436 --> 00:01:11,396 Speaker 1: extensively on black holes. Don't take my word for it 14 00:01:11,396 --> 00:01:13,156 Speaker 1: that and he's the right person to talk to. He's 15 00:01:13,156 --> 00:01:15,396 Speaker 1: one of every prize there is to win in the 16 00:01:15,436 --> 00:01:19,756 Speaker 1: space of theoretical physics. And Andy is also a director 17 00:01:19,756 --> 00:01:22,156 Speaker 1: of the Center for Fundamental Laws of Nature at Harvard. 18 00:01:22,476 --> 00:01:24,156 Speaker 1: On top of that, he's also one of the co 19 00:01:24,276 --> 00:01:28,156 Speaker 1: directors of the black Hole Initiative here at Harvard University 20 00:01:28,156 --> 00:01:30,556 Speaker 1: where I'm speaking to Andy today. Andy, thank you so 21 00:01:30,676 --> 00:01:34,636 Speaker 1: much for coming and joining great to be here. Ah. So, Andy, 22 00:01:34,756 --> 00:01:37,996 Speaker 1: let's just start with the image, which is a great 23 00:01:38,116 --> 00:01:43,156 Speaker 1: headline grabber and something that is extraordinarily beautiful, but which 24 00:01:43,196 --> 00:01:47,716 Speaker 1: strictly speaking, isn't a classic photographic image, whatever the world 25 00:01:47,756 --> 00:01:50,996 Speaker 1: may imagine. So say a word, if you will, about 26 00:01:51,116 --> 00:01:54,076 Speaker 1: what we are seeing, what it is, and then from 27 00:01:54,076 --> 00:01:57,796 Speaker 1: there we can move on to what it tells us. Okay, well, 28 00:01:58,916 --> 00:02:01,676 Speaker 1: I'd like to back up a little bit. It was 29 00:02:01,716 --> 00:02:07,196 Speaker 1: a hundred years ago that Einstein predicted with his equations 30 00:02:07,236 --> 00:02:10,836 Speaker 1: that there would be black holes, and people have been 31 00:02:10,916 --> 00:02:13,996 Speaker 1: arguing about them for most of the time, not believing 32 00:02:14,036 --> 00:02:18,276 Speaker 1: that they exist. Einstein wrote a paper nineteen thirty eight 33 00:02:18,316 --> 00:02:21,956 Speaker 1: saying black holes don't exist. Most people thought they didn't 34 00:02:21,996 --> 00:02:27,956 Speaker 1: exist until probably the seventies. And how they behave, what's 35 00:02:28,036 --> 00:02:34,596 Speaker 1: inside them, why they're there, has been a central debate 36 00:02:34,916 --> 00:02:38,276 Speaker 1: in physics for the last one hundred years. I have 37 00:02:38,436 --> 00:02:43,916 Speaker 1: spent the majority of my scientific career thinking about them, 38 00:02:43,956 --> 00:02:48,116 Speaker 1: trying to understand them, along with hundreds of other people, 39 00:02:48,756 --> 00:02:52,596 Speaker 1: and then all of a sudden to see it, to 40 00:02:52,716 --> 00:02:56,556 Speaker 1: see a picture of it, like Wow, that thing is real, 41 00:02:57,396 --> 00:03:00,956 Speaker 1: it's really it's really it's not. We're not the only 42 00:03:00,956 --> 00:03:03,476 Speaker 1: ones who have that. You could be the deepest specialist 43 00:03:03,516 --> 00:03:06,476 Speaker 1: and you're moved by it. I promise you that we 44 00:03:06,516 --> 00:03:10,476 Speaker 1: have a bunch bore. It rocked our worlds to like 45 00:03:10,996 --> 00:03:13,836 Speaker 1: see this thing that we've been talking about our whole lives. 46 00:03:13,836 --> 00:03:16,156 Speaker 1: So there it is, you know, even though you knew 47 00:03:16,156 --> 00:03:18,436 Speaker 1: it was there. We knew it was there. But there 48 00:03:18,516 --> 00:03:22,636 Speaker 1: is a big difference between knowing something's there and seeing it. 49 00:03:23,076 --> 00:03:26,156 Speaker 1: You know, maybe there was still that tidy bagging about 50 00:03:26,436 --> 00:03:30,676 Speaker 1: I don't know, but it really is great to see it. 51 00:03:30,676 --> 00:03:32,876 Speaker 1: It's a great thing actually to hear that from a physicist, 52 00:03:32,916 --> 00:03:36,796 Speaker 1: because when non physicists like me, mere lay people, we 53 00:03:37,076 --> 00:03:39,356 Speaker 1: instinctively have the feeling if we don't see something, maybe 54 00:03:39,356 --> 00:03:41,556 Speaker 1: it's not there. And then the physicists tell us it's 55 00:03:41,596 --> 00:03:45,156 Speaker 1: all equations, it's all logic, there are experiments that validate 56 00:03:45,196 --> 00:03:47,476 Speaker 1: these things. Take it on faith, you know, like you'll 57 00:03:47,476 --> 00:03:49,916 Speaker 1: never fully understand those things, but we know. And so 58 00:03:49,996 --> 00:03:52,356 Speaker 1: to hear that you too, or even you like to 59 00:03:52,396 --> 00:03:54,116 Speaker 1: actually see stuff as a kind of I don't know, 60 00:03:54,156 --> 00:03:57,196 Speaker 1: there's like some epistemological relief to me. And hearing that, yeah, yeah, 61 00:03:57,836 --> 00:03:59,836 Speaker 1: so what is it that we are in fact seeing 62 00:03:59,996 --> 00:04:04,396 Speaker 1: a black hole, by definition, is a region of space 63 00:04:04,436 --> 00:04:07,836 Speaker 1: and time from which no light escapes. So we're not 64 00:04:07,916 --> 00:04:10,996 Speaker 1: seeing light from the black hole. What we're really seeing 65 00:04:11,596 --> 00:04:17,196 Speaker 1: is light emitted by gases swirling around the black hole, 66 00:04:17,636 --> 00:04:20,556 Speaker 1: things that we don't understand very well. And we're seeing 67 00:04:20,596 --> 00:04:23,996 Speaker 1: the shadow of the black hole. So that dark spot 68 00:04:24,356 --> 00:04:26,756 Speaker 1: in the middle of that picture, the absence in the 69 00:04:26,756 --> 00:04:28,436 Speaker 1: middle of the breast, the absence in the middle of 70 00:04:28,436 --> 00:04:31,356 Speaker 1: the picture is where the black hole is. One of 71 00:04:31,356 --> 00:04:33,396 Speaker 1: the ways that was central too, or the main thing 72 00:04:33,396 --> 00:04:35,876 Speaker 1: that was central to making this telescope able to see 73 00:04:35,916 --> 00:04:38,836 Speaker 1: something so extraordinarily far away, was to turn the whole 74 00:04:38,836 --> 00:04:42,196 Speaker 1: Earth into a telescope. How does that work? We get 75 00:04:42,236 --> 00:04:46,476 Speaker 1: to the size of the Earth because we take about 76 00:04:46,516 --> 00:04:50,076 Speaker 1: eight different telescopes located at different points around the Earth 77 00:04:50,556 --> 00:04:54,356 Speaker 1: and we synchronize them and so it's of course not 78 00:04:54,436 --> 00:04:58,996 Speaker 1: a complete lens covering the entire Earth, but it's still 79 00:04:59,956 --> 00:05:02,676 Speaker 1: gives you a lot of resolving power if you can 80 00:05:02,756 --> 00:05:06,996 Speaker 1: just grab the light at those separate points. And as 81 00:05:06,996 --> 00:05:09,516 Speaker 1: an accomplishment, the creation of the image with all of 82 00:05:09,556 --> 00:05:17,116 Speaker 1: its coolness is scientifically significant. Why for several reasons. First 83 00:05:17,116 --> 00:05:20,516 Speaker 1: of all, it is in and of itself a spectacular 84 00:05:21,156 --> 00:05:25,916 Speaker 1: technical accomplishment, one that would not have been possible ten 85 00:05:25,996 --> 00:05:32,276 Speaker 1: years ago. It required many things. It required amazing improvements 86 00:05:32,276 --> 00:05:37,436 Speaker 1: in the accuracy of atomic clocks, um, it required uh, 87 00:05:38,036 --> 00:05:43,516 Speaker 1: bigger hard drives, bigger data processing capabilities, it recovered. I 88 00:05:43,516 --> 00:05:45,396 Speaker 1: read at one point that the data was so much 89 00:05:45,396 --> 00:05:47,476 Speaker 1: that it actually had to be flown from one place. Yeah, 90 00:05:47,476 --> 00:05:51,676 Speaker 1: because the Internet couldn't accommodated. Right at Sheep himself, I 91 00:05:51,716 --> 00:05:56,116 Speaker 1: saw lugging around these you know, discs with the you know, 92 00:05:56,156 --> 00:05:59,836 Speaker 1: he would go down to Mexico, go up to the 93 00:05:59,836 --> 00:06:03,276 Speaker 1: top of the mountain and lug lug it back. Of course, 94 00:06:03,276 --> 00:06:06,356 Speaker 1: the whole team was working on it. But Shep is 95 00:06:06,396 --> 00:06:10,596 Speaker 1: the director of is the direct and your your co 96 00:06:10,716 --> 00:06:14,156 Speaker 1: director at the black the director of this event Horizon 97 00:06:14,236 --> 00:06:17,916 Speaker 1: project at a great great scientist and uh, and the 98 00:06:17,996 --> 00:06:20,916 Speaker 1: algorithm has also gotten some attention and deserves some attention. 99 00:06:20,996 --> 00:06:26,356 Speaker 1: I take it produced by Katie Bowman, a recent post doc. Right, Yes, 100 00:06:26,476 --> 00:06:29,116 Speaker 1: there were of course, the whole there's there's a big 101 00:06:29,236 --> 00:06:34,156 Speaker 1: team of one hundred to two hundred people, and you know, 102 00:06:34,196 --> 00:06:37,716 Speaker 1: all this kind of big science is done in a 103 00:06:38,236 --> 00:06:40,436 Speaker 1: big teams and big teams now and it's it's the 104 00:06:40,476 --> 00:06:44,076 Speaker 1: only way it could can be done. But number one 105 00:06:44,076 --> 00:06:47,916 Speaker 1: of the big technical accomplishment. Number Two, there is the 106 00:06:47,956 --> 00:06:53,116 Speaker 1: importance of having seen these objects you know, that should 107 00:06:53,236 --> 00:06:58,436 Speaker 1: be shouldn't be underestimated. Number three, it's only the beginning. Um. 108 00:06:58,476 --> 00:07:03,516 Speaker 1: One of the things that struck me when I saw 109 00:07:03,556 --> 00:07:08,316 Speaker 1: the papers was, which I was not privy too before 110 00:07:08,916 --> 00:07:15,076 Speaker 1: the the general release, was how little actual observing time 111 00:07:15,156 --> 00:07:19,036 Speaker 1: they had when I first met Chapter ten fifteen years ago. 112 00:07:19,156 --> 00:07:21,196 Speaker 1: This project was you know, it was it was a 113 00:07:21,276 --> 00:07:24,356 Speaker 1: dark horse. It was it was not, you know, the 114 00:07:24,876 --> 00:07:30,756 Speaker 1: center of astronomical efforts. Um. And it was a funny idea, 115 00:07:31,036 --> 00:07:33,396 Speaker 1: but one that the more you thought about it, the 116 00:07:33,436 --> 00:07:35,956 Speaker 1: more since it made Why was it Why was that 117 00:07:36,036 --> 00:07:39,116 Speaker 1: just panenthetically? Why why wasn't it at the centerpiece of 118 00:07:39,316 --> 00:07:41,436 Speaker 1: as you say, black hole so crucial, so important and 119 00:07:41,916 --> 00:07:43,796 Speaker 1: seeing it would be a big deal, you know, because 120 00:07:43,836 --> 00:07:46,716 Speaker 1: it wasn't. There many ways it could have failed, right, 121 00:07:47,116 --> 00:07:51,676 Speaker 1: They had to increase their observational precision by many orders 122 00:07:51,716 --> 00:07:55,876 Speaker 1: of magnitude over whatever what anybody had ever seen. What 123 00:07:55,916 --> 00:08:00,316 Speaker 1: they did. It's like standing in Boston and reading the 124 00:08:00,436 --> 00:08:03,836 Speaker 1: data on a quarter in Los Angeles. That is, that 125 00:08:04,036 --> 00:08:07,596 Speaker 1: is the precision that they had to have to image 126 00:08:07,716 --> 00:08:10,236 Speaker 1: this black hole. The general public tends to forget, I 127 00:08:10,236 --> 00:08:12,716 Speaker 1: tend to forget that the funding of scientific projects is 128 00:08:12,756 --> 00:08:14,556 Speaker 1: always a kind of a bet or a gamble. It's 129 00:08:14,556 --> 00:08:17,236 Speaker 1: a beat, and when the odds of the success are 130 00:08:17,236 --> 00:08:20,716 Speaker 1: relatively low, the funders are skeptical about putting too much 131 00:08:20,716 --> 00:08:24,076 Speaker 1: money on that gamble. When people thought about it ten 132 00:08:24,116 --> 00:08:25,756 Speaker 1: or fifteen years ago, did they think, well, if we 133 00:08:25,796 --> 00:08:28,396 Speaker 1: get enough computing power, this is one of the things 134 00:08:28,436 --> 00:08:31,036 Speaker 1: will fix. And it's a question of whether we'll ever 135 00:08:31,076 --> 00:08:33,276 Speaker 1: get enough computing power, or was it rather a question 136 00:08:33,316 --> 00:08:36,436 Speaker 1: of other aspects of the technical difficulty of doing it. 137 00:08:36,836 --> 00:08:39,276 Speaker 1: He wasn't dismissed, and the thing was funded in it 138 00:08:39,636 --> 00:08:42,636 Speaker 1: and it did happen, but it was not obvious. It 139 00:08:42,676 --> 00:08:45,996 Speaker 1: was not obvious. You know, the Earth is just barely 140 00:08:46,036 --> 00:08:49,636 Speaker 1: big enough to image this thing. It's also very important 141 00:08:49,716 --> 00:08:55,236 Speaker 1: that the wavelength that they could access with this large 142 00:08:55,796 --> 00:08:59,676 Speaker 1: collator array is one in which there isn't a lot 143 00:08:59,756 --> 00:09:03,756 Speaker 1: of absorption between us and the black hole. You know 144 00:09:03,796 --> 00:09:06,756 Speaker 1: that there isn't a lot of dust that blocks the 145 00:09:06,836 --> 00:09:10,156 Speaker 1: light at that that wavelength. Right, So there were some 146 00:09:10,236 --> 00:09:14,476 Speaker 1: coincidence that you know, Luck smiled on the project. It 147 00:09:14,596 --> 00:09:17,596 Speaker 1: might not have been possible. I don't I doubt if 148 00:09:17,636 --> 00:09:21,276 Speaker 1: you get cheppy, you could ask him, but I doubt 149 00:09:21,316 --> 00:09:25,316 Speaker 1: he would have been certain you ten fifteen years go 150 00:09:25,476 --> 00:09:27,916 Speaker 1: that it would work. But I was going on to say, 151 00:09:28,556 --> 00:09:31,556 Speaker 1: they didn't get all that much observing time. Now clearly 152 00:09:31,596 --> 00:09:36,956 Speaker 1: they'll get more, right, there will be better resolution, more 153 00:09:36,996 --> 00:09:41,836 Speaker 1: observing time, they'll set one up out in space. So 154 00:09:42,276 --> 00:09:44,916 Speaker 1: there we are entering an era. So this is the 155 00:09:44,956 --> 00:09:49,956 Speaker 1: opening of that era of precision black hole astronomy. So 156 00:09:50,036 --> 00:09:53,236 Speaker 1: let's talk about now what we can see and what 157 00:09:53,276 --> 00:09:56,676 Speaker 1: we will see when we get more time, more observations, 158 00:09:56,716 --> 00:09:58,476 Speaker 1: and the emergence of what you described as a new 159 00:09:58,596 --> 00:10:02,276 Speaker 1: a new science really of precision black hole astronomy. You 160 00:10:02,356 --> 00:10:06,516 Speaker 1: with some collaborators have been actually making predictions the way 161 00:10:06,556 --> 00:10:10,156 Speaker 1: theoretical physicists like to do. You know, a theoretical physicist 162 00:10:10,596 --> 00:10:13,916 Speaker 1: makes predictions and sometimes they can be tested in his 163 00:10:14,036 --> 00:10:17,156 Speaker 1: or her lifetime. Sometimes it takes generations. In this instance, 164 00:10:17,156 --> 00:10:20,276 Speaker 1: you've made a series of observational predictions the things that 165 00:10:20,316 --> 00:10:23,916 Speaker 1: you expect can be picked up, and now that will 166 00:10:23,916 --> 00:10:26,556 Speaker 1: turn to whether they will in fact be be picked up, 167 00:10:26,556 --> 00:10:29,716 Speaker 1: which is dramatic and exciting. What kinds of predictions have 168 00:10:29,836 --> 00:10:33,156 Speaker 1: you already been making and when can we expect to 169 00:10:33,196 --> 00:10:39,396 Speaker 1: see results. I've been working with Alex Sasa, Delilah Gates, 170 00:10:39,396 --> 00:10:45,556 Speaker 1: and Dan Coppetts, and we are very interested in what 171 00:10:45,716 --> 00:10:50,596 Speaker 1: happens very near the horizon of of the black hole, 172 00:10:50,716 --> 00:10:54,636 Speaker 1: right at the edge of that inner shadow, and remind people, 173 00:10:54,756 --> 00:10:58,756 Speaker 1: just because it's never bad, to redefine it the event horizon. Yeah. 174 00:10:58,796 --> 00:11:05,156 Speaker 1: So the event horizon is the boundary of the region 175 00:11:05,236 --> 00:11:10,356 Speaker 1: of space time from which light rays connects escape. So 176 00:11:10,436 --> 00:11:14,156 Speaker 1: in practical terms, it's the edge of that you're inside 177 00:11:14,156 --> 00:11:16,276 Speaker 1: the event horizon, you're in the black holiness of the 178 00:11:16,316 --> 00:11:19,156 Speaker 1: black hole. Yeah. Once you go inside the event horizon, 179 00:11:19,196 --> 00:11:22,996 Speaker 1: you can never come out, and so your predictions relate 180 00:11:23,036 --> 00:11:26,076 Speaker 1: to what's happening at that edge, right. And one of 181 00:11:26,076 --> 00:11:30,716 Speaker 1: the things that we are very interesting in is that 182 00:11:31,996 --> 00:11:37,516 Speaker 1: black holes can spin around like a top and it's 183 00:11:37,556 --> 00:11:41,316 Speaker 1: believed that the M eighty seven, the black hole that 184 00:11:41,356 --> 00:11:45,996 Speaker 1: we've just seen, is spinning at light speed or very 185 00:11:46,076 --> 00:11:49,756 Speaker 1: near light speed. So there has been claims of this 186 00:11:49,916 --> 00:11:54,876 Speaker 1: from other kinds of measurements in the literature, and a 187 00:11:54,956 --> 00:12:00,836 Speaker 1: black hole which spins at light speed does some incredibly 188 00:12:00,916 --> 00:12:04,196 Speaker 1: peculiar things. Is you get near the edge of the 189 00:12:04,276 --> 00:12:08,796 Speaker 1: black hole, a long sort of funnel or wormhole forms. 190 00:12:08,796 --> 00:12:11,716 Speaker 1: It's kind of like a tornado with a long spout. 191 00:12:12,796 --> 00:12:18,036 Speaker 1: And as the black hole spins faster and faster, that's spout. 192 00:12:18,916 --> 00:12:21,876 Speaker 1: It sounds like I'm talking about sub sides fiction stuff. 193 00:12:22,276 --> 00:12:24,636 Speaker 1: But everything with respected black holes though, so go on 194 00:12:25,276 --> 00:12:27,436 Speaker 1: sounds like I'm talking about sizes fiction stuff. But we 195 00:12:28,036 --> 00:12:32,396 Speaker 1: maybe seeing this kind of black hole. Now the spout 196 00:12:32,556 --> 00:12:35,516 Speaker 1: or the wormhole that goes to the horizon, the black 197 00:12:35,556 --> 00:12:42,356 Speaker 1: hole actually becomes an infinitely long tube protruding out of 198 00:12:42,436 --> 00:12:46,556 Speaker 1: the out of space doot, and that will lead to 199 00:12:46,956 --> 00:12:48,756 Speaker 1: about to ask you where where the wormhole leads. But 200 00:12:48,796 --> 00:12:51,836 Speaker 1: if it's infinitely long, the answer is, yeah, it leads 201 00:12:51,836 --> 00:12:56,076 Speaker 1: to infinity. It goes, it leads to infinity. But before 202 00:12:56,116 --> 00:12:59,556 Speaker 1: it gets infinitely long where the wormhole leads it goes 203 00:12:59,596 --> 00:13:02,836 Speaker 1: into the rise of black hole, and once it crosses there, 204 00:13:03,276 --> 00:13:06,596 Speaker 1: we don't know. We don't know what's inside a black hole. 205 00:13:06,676 --> 00:13:08,956 Speaker 1: So the part of the wormhole is in the very 206 00:13:09,196 --> 00:13:11,756 Speaker 1: edge of the wormhole is at the event horizon, right 207 00:13:11,876 --> 00:13:14,716 Speaker 1: as it were, and then it extends infinitely away from 208 00:13:14,756 --> 00:13:18,476 Speaker 1: the black hole and connects on to the space time 209 00:13:18,556 --> 00:13:22,396 Speaker 1: that you and I live in, and that so we're 210 00:13:22,476 --> 00:13:25,796 Speaker 1: seeing into what does sound like science fiction. It does 211 00:13:25,836 --> 00:13:28,196 Speaker 1: sound like science fiction, but we're seeing it, you know, 212 00:13:28,836 --> 00:13:31,556 Speaker 1: And how would that be seen? I mean, what would 213 00:13:31,556 --> 00:13:34,556 Speaker 1: that as it were look like? We in our paper 214 00:13:35,476 --> 00:13:43,996 Speaker 1: gave some very specific predictions about what the polarization of 215 00:13:44,036 --> 00:13:47,476 Speaker 1: the light coming out will be. It's known that it's polarized. 216 00:13:48,556 --> 00:13:50,476 Speaker 1: Not that's coming from the black hole, but the lights, sorry, 217 00:13:50,476 --> 00:13:53,076 Speaker 1: the light and the halo. Yes, it's known that it's 218 00:13:53,196 --> 00:13:58,396 Speaker 1: polar polarized, but the distribution hasn't been extracted from the 219 00:13:58,476 --> 00:14:01,236 Speaker 1: data yet. I think they've already seen it. They have 220 00:14:01,396 --> 00:14:05,276 Speaker 1: these mountains of hard drives the data they need to process, 221 00:14:06,076 --> 00:14:11,036 Speaker 1: and they haven't extracted from that what the polarization is. 222 00:14:11,836 --> 00:14:15,596 Speaker 1: Luck will have to shine on us for Are there 223 00:14:15,676 --> 00:14:19,596 Speaker 1: measurements to be sufficient to prove what you've predicted? Yeah? Right, 224 00:14:19,956 --> 00:14:23,596 Speaker 1: because they weren't there looking for what you predicted. Well, 225 00:14:23,636 --> 00:14:28,316 Speaker 1: that's right, and also might not be this round might 226 00:14:28,396 --> 00:14:32,076 Speaker 1: not be a precise enough measurement for our prediction to 227 00:14:32,196 --> 00:14:38,196 Speaker 1: be verified or not. But I'd stress that our prediction 228 00:14:38,956 --> 00:14:42,636 Speaker 1: is a prediction of the Einstein equation. It's just the 229 00:14:42,716 --> 00:14:48,596 Speaker 1: Einstein equation in a very unusual circumstance, not like the 230 00:14:48,596 --> 00:14:52,276 Speaker 1: predictions that Einstein made, where the effects of general relativity 231 00:14:52,396 --> 00:14:55,356 Speaker 1: on the bending of light or in the Solar system 232 00:14:55,596 --> 00:14:59,556 Speaker 1: they were small effects. Yes here, it's huge effect. Here 233 00:14:59,556 --> 00:15:04,556 Speaker 1: it changes dramatically the nature of space and time, everything 234 00:15:04,556 --> 00:15:07,356 Speaker 1: that we really have to to somebody even reimagine what 235 00:15:07,436 --> 00:15:09,996 Speaker 1: we are, what we mean in ordinary language term. Yeah. 236 00:15:10,556 --> 00:15:14,636 Speaker 1: So we think that if you were to go in 237 00:15:14,676 --> 00:15:17,756 Speaker 1: a spaceship to near the horizon of M eighty seven, 238 00:15:18,356 --> 00:15:22,956 Speaker 1: you would be forced to whirl around it. You couldn't 239 00:15:22,996 --> 00:15:25,516 Speaker 1: just approach it straight on. There would be a force 240 00:15:25,636 --> 00:15:28,036 Speaker 1: by the warping of space time that would drag you 241 00:15:28,116 --> 00:15:32,756 Speaker 1: around like a tornado and pull you down this down 242 00:15:32,796 --> 00:15:36,076 Speaker 1: the drain into the down drain at the speed of 243 00:15:36,156 --> 00:15:40,556 Speaker 1: light through the wormhole. Yeah, bow the wormhole to the Yeah, 244 00:15:40,796 --> 00:15:42,636 Speaker 1: and it would grab you well before you got to 245 00:15:42,636 --> 00:15:45,916 Speaker 1: the event horizon. So, in practical terms, though it's outside 246 00:15:45,916 --> 00:15:48,436 Speaker 1: the event horizon, you're descent into the black hole would 247 00:15:48,436 --> 00:15:50,956 Speaker 1: begin a lot sooner than it. Otherwise it would be 248 00:15:51,876 --> 00:15:53,996 Speaker 1: if it were really spitting all the way at the 249 00:15:54,036 --> 00:15:56,596 Speaker 1: speed of light, it would grab you when you were 250 00:15:56,756 --> 00:16:00,156 Speaker 1: infinitely far away from the event horizon, but suck you 251 00:16:00,276 --> 00:16:04,356 Speaker 1: there in a finite amount of time by pulling you 252 00:16:04,436 --> 00:16:07,556 Speaker 1: up to the speed of light. But when you say 253 00:16:07,636 --> 00:16:09,116 Speaker 1: we grab you when so I'm just trying to get 254 00:16:09,156 --> 00:16:11,236 Speaker 1: my mind around this and not so much succeeding when 255 00:16:11,276 --> 00:16:14,596 Speaker 1: you say would grab you the reason you're infinitely far 256 00:16:14,636 --> 00:16:17,476 Speaker 1: away is that sounds as though, well, we're infinitely we're 257 00:16:17,476 --> 00:16:20,036 Speaker 1: at some distance less than infinitely far away from M 258 00:16:20,116 --> 00:16:21,876 Speaker 1: eighty seven right now. Why doesn't it grab up? Oh, 259 00:16:21,916 --> 00:16:25,636 Speaker 1: we don't know that, because we're not infinitely far away 260 00:16:26,396 --> 00:16:30,156 Speaker 1: from the edge of the wormhole, and the wormhole could 261 00:16:30,196 --> 00:16:33,476 Speaker 1: be infinitely long. I don't think it is. You'd have 262 00:16:33,516 --> 00:16:35,516 Speaker 1: to be going absolutely at the speed of light for 263 00:16:35,556 --> 00:16:37,396 Speaker 1: it to be infinitely long. But it could be very 264 00:16:37,476 --> 00:16:40,876 Speaker 1: very long, and so we could be much farther away 265 00:16:40,916 --> 00:16:44,356 Speaker 1: than it seems. I mean, the rest of the universe exists. 266 00:16:44,716 --> 00:16:47,356 Speaker 1: The rest of the universe is not presently I take 267 00:16:47,396 --> 00:16:53,276 Speaker 1: it currently captured by the wormhole right and spinning at 268 00:16:53,276 --> 00:16:56,196 Speaker 1: some very rapid speed around the black hole, and on 269 00:16:56,276 --> 00:16:58,756 Speaker 1: the way to the event horizon, we're not headed all 270 00:16:58,836 --> 00:17:01,436 Speaker 1: headed that way, I take it right. So my question 271 00:17:01,516 --> 00:17:07,036 Speaker 1: is why, Well, because we're far away week, but when 272 00:17:07,076 --> 00:17:10,676 Speaker 1: you get to some critical point instance, all of a 273 00:17:10,716 --> 00:17:17,316 Speaker 1: sudden it's a spinning black hole is surrounded by a 274 00:17:17,476 --> 00:17:21,716 Speaker 1: science fiction region which was discovered in the sixties called 275 00:17:21,716 --> 00:17:26,396 Speaker 1: the ergosphere. And life inside the ergosphere is very different 276 00:17:26,436 --> 00:17:30,276 Speaker 1: than life in this room, and existence rather than life, 277 00:17:30,276 --> 00:17:34,476 Speaker 1: because nothing's living once you get into the ergosphere. Anyone 278 00:17:34,516 --> 00:17:37,836 Speaker 1: who enters the ergosphere, which is still outside the black holes, 279 00:17:38,636 --> 00:17:42,876 Speaker 1: you you are forced to spin around in the in 280 00:17:42,916 --> 00:17:48,116 Speaker 1: the tornado vortex outside the black hole, and the wormhole 281 00:17:48,196 --> 00:17:51,316 Speaker 1: is a big extension of that. The wormhole is the 282 00:17:51,676 --> 00:17:54,276 Speaker 1: is the vortex going Yeah, it is the vortex going 283 00:17:54,316 --> 00:17:57,236 Speaker 1: down to the black hole. So we what we know 284 00:17:57,396 --> 00:18:00,036 Speaker 1: really is our distance from the mouth of the wormhole, 285 00:18:00,396 --> 00:18:04,916 Speaker 1: not how long the wormhole is. Now nobody thinks it's 286 00:18:04,916 --> 00:18:08,796 Speaker 1: infinitely long, but it could be long enough to be 287 00:18:08,836 --> 00:18:13,956 Speaker 1: in testing and long enough to make a signal. And 288 00:18:14,156 --> 00:18:17,956 Speaker 1: how how will the observation of the polarization of the 289 00:18:18,076 --> 00:18:21,436 Speaker 1: light that presently is visible at the edge of the 290 00:18:21,436 --> 00:18:24,556 Speaker 1: black hole get you to some better understanding of the 291 00:18:25,076 --> 00:18:28,516 Speaker 1: of the wormhole. Well, the worm it will verify the 292 00:18:28,556 --> 00:18:32,436 Speaker 1: existence of of the wormhole, I say. And the polarization 293 00:18:32,556 --> 00:18:34,996 Speaker 1: is not the only thing um. There are other things 294 00:18:34,996 --> 00:18:39,676 Speaker 1: that you might try to to to measure. Now I 295 00:18:39,796 --> 00:18:44,156 Speaker 1: stress it there. We're just one of and not even 296 00:18:44,196 --> 00:18:47,556 Speaker 1: the most important, what of many groups who are in 297 00:18:47,596 --> 00:18:51,076 Speaker 1: the vent Horizon telescope themselves are making predictions. Of course, 298 00:18:51,076 --> 00:18:54,876 Speaker 1: they had to compare their their theory to the theoretical 299 00:18:54,876 --> 00:18:59,396 Speaker 1: predictions to their observation to get their estimate that they 300 00:18:59,436 --> 00:19:03,836 Speaker 1: published of the mass. We are especially interested in some 301 00:19:03,916 --> 00:19:09,076 Speaker 1: of these novel aspects because first of all, because they're 302 00:19:09,316 --> 00:19:12,436 Speaker 1: weird and interesting and they're there and we're seeing them, 303 00:19:12,476 --> 00:19:17,916 Speaker 1: and also because they tie in with ideas about the 304 00:19:17,996 --> 00:19:21,236 Speaker 1: quantum structure of black holes and what's inside a black 305 00:19:21,276 --> 00:19:24,396 Speaker 1: hole in a very intricate way. And that question of 306 00:19:24,396 --> 00:19:29,916 Speaker 1: what's inside is hugely controversial and fascinating. So the question 307 00:19:29,956 --> 00:19:33,956 Speaker 1: of what's inside also philosophical, if I yeah, I venture 308 00:19:33,956 --> 00:19:37,756 Speaker 1: to use that word. There are philosophical aspects to it, 309 00:19:38,636 --> 00:19:42,596 Speaker 1: but there is a very sharp meaning to it because, 310 00:19:43,316 --> 00:19:48,556 Speaker 1: as Stephen Hawking showed, if you wait long enough and 311 00:19:48,756 --> 00:19:52,796 Speaker 1: even the you know, event Horizon team won't have this 312 00:19:52,956 --> 00:19:55,436 Speaker 1: much patience. I'd be like a very very long time, 313 00:19:56,796 --> 00:20:05,876 Speaker 1: the black hole will evaporate and what's inside using quantum 314 00:20:05,916 --> 00:20:10,556 Speaker 1: effects will come out. And then the question is would 315 00:20:10,596 --> 00:20:12,476 Speaker 1: the thing that came out, would what was inside to 316 00:20:12,516 --> 00:20:15,076 Speaker 1: come out and have some information? And then there is 317 00:20:15,116 --> 00:20:18,836 Speaker 1: an inside that we would ultimately see if we could 318 00:20:18,836 --> 00:20:24,436 Speaker 1: wait long enough, which I think, yeah, more than billions 319 00:20:24,676 --> 00:20:28,116 Speaker 1: moves it from philosophy to physics because there would because 320 00:20:28,116 --> 00:20:32,276 Speaker 1: it's not an unanswerable question. Well, it's a question people 321 00:20:32,276 --> 00:20:34,916 Speaker 1: could argue about. That's a separate, interesting question. What makes 322 00:20:34,916 --> 00:20:37,156 Speaker 1: something a physics question as opposed to philosopher ques I 323 00:20:37,236 --> 00:20:40,516 Speaker 1: was using a shorthand of imagining that physicists only like 324 00:20:40,636 --> 00:20:44,436 Speaker 1: questions that, in principle could be answered. It's a question 325 00:20:44,476 --> 00:20:47,516 Speaker 1: which can be answered with a goadoncan experiment when you're 326 00:20:47,516 --> 00:20:49,596 Speaker 1: do in your mind? Yes, I thought, you can't get 327 00:20:49,596 --> 00:20:52,836 Speaker 1: the funding to do it? Okay, right, So some people 328 00:20:52,836 --> 00:20:55,556 Speaker 1: would say infinite time, Well, you don't have infinite time. 329 00:20:55,876 --> 00:20:59,516 Speaker 1: Some people would say that physics is the study of 330 00:20:59,636 --> 00:21:03,156 Speaker 1: questions you could answer with real experiments that could be funded. 331 00:21:04,476 --> 00:21:07,396 Speaker 1: That's a pretty cramp though, view if it wouldn't cover 332 00:21:07,436 --> 00:21:10,356 Speaker 1: a lot of your your earlier work, wouldn't cover wouldn't 333 00:21:10,356 --> 00:21:11,956 Speaker 1: cover a lot of my work, right, And I think, 334 00:21:12,116 --> 00:21:13,676 Speaker 1: to be fair, I don't think that's what most non 335 00:21:13,716 --> 00:21:16,236 Speaker 1: physicists think. I think it's that would be a very 336 00:21:16,356 --> 00:21:19,596 Speaker 1: hard nosed, predictive, pragmatist view, and it's not physics if 337 00:21:19,596 --> 00:21:21,436 Speaker 1: I can't test it, you know, and get funding to 338 00:21:21,436 --> 00:21:24,076 Speaker 1: test it. Yea. The laws of nature presumably should be 339 00:21:24,636 --> 00:21:27,756 Speaker 1: resistant to being cabined by what we can fund. But 340 00:21:27,876 --> 00:21:31,156 Speaker 1: what's exciting to me here is that this observation is 341 00:21:31,236 --> 00:21:36,116 Speaker 1: touching the edge, possibly touching the edge of the things 342 00:21:36,156 --> 00:21:41,276 Speaker 1: that bearing on the issues of people that people think 343 00:21:41,316 --> 00:21:44,196 Speaker 1: about who want to understand what's really inside a black hole. 344 00:21:44,276 --> 00:21:48,116 Speaker 1: So you mentioned your friend Stephen Hawking, also your collaborator 345 00:21:48,916 --> 00:21:51,116 Speaker 1: who died not so long ago and with whom you 346 00:21:51,156 --> 00:21:52,796 Speaker 1: did a lot of work over the years, but most 347 00:21:52,836 --> 00:21:55,956 Speaker 1: recently you had been working on some pretty major projects 348 00:21:55,996 --> 00:21:58,556 Speaker 1: with him, also connected to black holes. Yeah, tell us 349 00:21:58,556 --> 00:22:02,876 Speaker 1: a little bit about that. Yes, Stephen, in his most 350 00:22:03,316 --> 00:22:08,876 Speaker 1: famous work in the Seven Daies, showed that with an 351 00:22:09,156 --> 00:22:13,156 Speaker 1: argument that is so simple and elegant that it has 352 00:22:13,236 --> 00:22:19,676 Speaker 1: never been seriously questioned that when you include quantum effects, 353 00:22:20,596 --> 00:22:26,796 Speaker 1: black holes are not completely black. That quantum effects allow 354 00:22:26,876 --> 00:22:31,156 Speaker 1: a sort of the uncertainty principle about where the horizon 355 00:22:31,196 --> 00:22:35,956 Speaker 1: of the black hole is allows a small amount of 356 00:22:36,036 --> 00:22:40,196 Speaker 1: light and matter to slowly trickle out of the of 357 00:22:40,196 --> 00:22:44,276 Speaker 1: a black hole a very slow rate. So those are 358 00:22:44,276 --> 00:22:46,796 Speaker 1: big things, and let me try a very very lay 359 00:22:46,836 --> 00:22:51,316 Speaker 1: person's attempt to make sense of that. If we imagined 360 00:22:52,196 --> 00:22:56,756 Speaker 1: determinative locations and laws of physics, then nothing escapes the 361 00:22:56,796 --> 00:22:59,116 Speaker 1: black hole. That's what makes it a black hole. But 362 00:23:00,036 --> 00:23:03,756 Speaker 1: one of the key points of quantum theory is it 363 00:23:03,916 --> 00:23:09,076 Speaker 1: precisely you can't pin down the exact location of every 364 00:23:09,276 --> 00:23:12,836 Speaker 1: quantum phenomenon. And since you can't pin it down exactly, 365 00:23:13,196 --> 00:23:16,676 Speaker 1: that puts enough wiggle room, if you will, into the 366 00:23:16,796 --> 00:23:19,876 Speaker 1: equation that there is some information in the black hole 367 00:23:19,916 --> 00:23:22,636 Speaker 1: that might be capable of being discovered. How's that for 368 00:23:22,676 --> 00:23:25,796 Speaker 1: a first order? That's right. So quantum mechanics says that 369 00:23:25,916 --> 00:23:31,396 Speaker 1: the horizon and the black hole must fluctuate around a 370 00:23:31,436 --> 00:23:34,756 Speaker 1: little bit, according must be slightly uncertain, and so that 371 00:23:36,316 --> 00:23:40,116 Speaker 1: gives just enough wiggle room for a few quantum particles 372 00:23:40,156 --> 00:23:44,636 Speaker 1: to escape from inside the black hole at a slow rate, 373 00:23:45,036 --> 00:23:49,596 Speaker 1: so that you began with describing Hawking's famous nineteen seventies 374 00:23:49,916 --> 00:23:52,796 Speaker 1: that was forty years ago, yep. And he gave an 375 00:23:52,876 --> 00:23:59,996 Speaker 1: argument that the information about how the black hole was 376 00:24:00,116 --> 00:24:05,636 Speaker 1: made would not escape, would not come out with this 377 00:24:05,796 --> 00:24:09,596 Speaker 1: leak of energy and particles and so on. Things would 378 00:24:09,636 --> 00:24:11,916 Speaker 1: come out, but not the information about how the black 379 00:24:11,916 --> 00:24:16,876 Speaker 1: black hole came to be made. He claimed, the present 380 00:24:17,236 --> 00:24:21,876 Speaker 1: does not determine the future and cannot, even in principle, 381 00:24:22,036 --> 00:24:25,716 Speaker 1: be used to reconstruct the past. Bad news for historians, 382 00:24:26,356 --> 00:24:28,636 Speaker 1: bad news for hystories for people who like free will 383 00:24:28,636 --> 00:24:33,396 Speaker 1: in the future maybe, but bad news for physicists because 384 00:24:33,636 --> 00:24:37,196 Speaker 1: it's equivalent to saying there aren't absolute laws of physics, 385 00:24:37,596 --> 00:24:40,996 Speaker 1: because a law of physics is supposed to predict the 386 00:24:41,036 --> 00:24:44,436 Speaker 1: future from the present. It was a very simple argument, 387 00:24:45,516 --> 00:24:49,716 Speaker 1: and people didn't like the conclusion. It had been questioned 388 00:24:49,756 --> 00:24:54,436 Speaker 1: in many different ways, but none of the ways in 389 00:24:54,476 --> 00:24:58,876 Speaker 1: which it was questioned really stuck. So a few years 390 00:24:58,876 --> 00:25:05,636 Speaker 1: ago I found, while investigating other problems in physics, I 391 00:25:05,796 --> 00:25:10,836 Speaker 1: came across what seemed to be an error in the 392 00:25:10,876 --> 00:25:18,596 Speaker 1: original flawed assumption in his original reasoning. Moreover, the nature 393 00:25:19,116 --> 00:25:24,556 Speaker 1: of the flaw suggested a research program for understanding what 394 00:25:24,876 --> 00:25:32,916 Speaker 1: really did happen. And I explained this to Stephen and 395 00:25:33,276 --> 00:25:36,196 Speaker 1: he was very excited about it, and I just say, 396 00:25:36,276 --> 00:25:38,756 Speaker 1: this is also it's a great model of what scientific 397 00:25:38,756 --> 00:25:43,156 Speaker 1: collaboration can be and isn't always You find a flaw 398 00:25:43,276 --> 00:25:47,396 Speaker 1: in an important claim by another famous physicist and you 399 00:25:47,476 --> 00:25:51,356 Speaker 1: call him up and you say, hey, there's a problem, 400 00:25:51,516 --> 00:25:54,436 Speaker 1: and that's collegial of you, and then he responds positively, 401 00:25:54,436 --> 00:25:56,236 Speaker 1: and that's collegial of him. This is the way it's 402 00:25:56,236 --> 00:25:59,876 Speaker 1: supposed to work in the textbooks. Yeah, and it really 403 00:25:59,916 --> 00:26:03,076 Speaker 1: does work this way for the for the most part. Yeah, 404 00:26:03,156 --> 00:26:05,676 Speaker 1: it's heartwarming. It's not like this in my end of 405 00:26:05,716 --> 00:26:08,276 Speaker 1: the academy. I promise you that. Well, it may be 406 00:26:08,396 --> 00:26:10,316 Speaker 1: related to the fact that there's no money in my 407 00:26:10,436 --> 00:26:14,036 Speaker 1: branch of science. I know there's a there's a there's 408 00:26:14,036 --> 00:26:18,996 Speaker 1: a money in those prizes. But go on. So he 409 00:26:19,116 --> 00:26:23,436 Speaker 1: and I and his colleague Malcolm Perry, he had some 410 00:26:23,476 --> 00:26:25,996 Speaker 1: ideas about how to proceed on this and to make 411 00:26:26,036 --> 00:26:29,676 Speaker 1: sense of it, and so we began a very active 412 00:26:29,756 --> 00:26:33,796 Speaker 1: and productive collaboration which went on for the last three 413 00:26:33,876 --> 00:26:38,516 Speaker 1: years with life and we're pushing forward in that direction. 414 00:26:38,556 --> 00:26:43,636 Speaker 1: It's looking promising, but we haven't delivered the goods, right. 415 00:26:43,756 --> 00:26:48,756 Speaker 1: We don't know yet that there isn't some reason this 416 00:26:48,876 --> 00:26:54,236 Speaker 1: is a technical issue rather than the fundamental right. When 417 00:26:54,276 --> 00:26:57,636 Speaker 1: you were describing how you came up with the original 418 00:26:57,676 --> 00:27:00,756 Speaker 1: thought that led to this collaboration, my reaction was you 419 00:27:00,796 --> 00:27:03,196 Speaker 1: were describing how you were thinking about something else in physics, 420 00:27:03,276 --> 00:27:06,996 Speaker 1: and then you hit upon reason to think that one 421 00:27:06,996 --> 00:27:09,556 Speaker 1: of Hawking's original assumptions was inaccurate. And it's struck me 422 00:27:09,716 --> 00:27:12,716 Speaker 1: that's a very andy way to go about things. One 423 00:27:12,716 --> 00:27:17,436 Speaker 1: of the key features of your contributions across the whole 424 00:27:17,516 --> 00:27:20,716 Speaker 1: range of areas where you've worked is that you find 425 00:27:20,836 --> 00:27:25,876 Speaker 1: and see correspondences between different areas of thought physics, math 426 00:27:26,396 --> 00:27:29,916 Speaker 1: that other people have never hit upon before. That's like 427 00:27:29,996 --> 00:27:32,756 Speaker 1: the Andy move, as it were, and it's quite a move. 428 00:27:33,156 --> 00:27:35,636 Speaker 1: So well, I don't think I have a pattern on 429 00:27:35,676 --> 00:27:37,996 Speaker 1: this move. But it's the structure of the field the 430 00:27:38,036 --> 00:27:44,956 Speaker 1: physics is. You know, there's many It's interconnected in surprising ways, 431 00:27:45,436 --> 00:27:49,916 Speaker 1: and it often happens. Maybe I'm lucky enough that it 432 00:27:49,996 --> 00:27:53,836 Speaker 1: happens to enough times that I'm not sure it looks 433 00:27:53,876 --> 00:27:56,756 Speaker 1: like a coincidence, but maybe coincidental in nature, but it's 434 00:27:56,796 --> 00:28:00,516 Speaker 1: not coincidental in you. But anyway, go on, and you know, 435 00:28:00,676 --> 00:28:04,596 Speaker 1: maybe one could say, you know, our creator didn't have 436 00:28:04,676 --> 00:28:08,756 Speaker 1: so many ideas that he kept using the same one 437 00:28:08,836 --> 00:28:12,836 Speaker 1: over overget and you solve a problem in one area 438 00:28:12,956 --> 00:28:17,516 Speaker 1: and it has a translation into another area. So that 439 00:28:17,636 --> 00:28:20,276 Speaker 1: hints at a kind of set of structures of unity. 440 00:28:20,276 --> 00:28:22,476 Speaker 1: I mean, you're sort of kidding about reusing the same idea. 441 00:28:22,676 --> 00:28:25,196 Speaker 1: What you really mean is that there is an underlying 442 00:28:25,276 --> 00:28:29,236 Speaker 1: unity and we are describing different parts of reality in 443 00:28:29,276 --> 00:28:31,996 Speaker 1: different ways. We've got these mathematical tools or these physics 444 00:28:32,036 --> 00:28:35,716 Speaker 1: tools to describe something, but we're actually describing a more 445 00:28:35,876 --> 00:28:41,996 Speaker 1: unified underlying phenomenon. Yeah, we have many ideas and we 446 00:28:42,076 --> 00:28:45,316 Speaker 1: often don't realize that they're the same idea. And is 447 00:28:45,356 --> 00:28:50,076 Speaker 1: it your belief that there is some directionality here? I mean, 448 00:28:50,636 --> 00:28:53,436 Speaker 1: now I'm aiming for something bigger, as it were, even 449 00:28:53,476 --> 00:28:57,196 Speaker 1: bigger than you know, than the wormhole and the black hole? 450 00:28:57,956 --> 00:29:02,116 Speaker 1: Are you a believer in direction in physics towards more 451 00:29:02,156 --> 00:29:05,876 Speaker 1: and more unification of our theoretical knowledge? Sometimes people talk 452 00:29:05,876 --> 00:29:08,596 Speaker 1: about a grand unified theory string theory, to which you've 453 00:29:08,596 --> 00:29:11,916 Speaker 1: made fundamental contributions. Is sometimes described as a step in 454 00:29:11,956 --> 00:29:13,996 Speaker 1: the direction of a grand unified theory or an aspiration 455 00:29:13,996 --> 00:29:16,356 Speaker 1: in that direction. I'm asking you to put it along 456 00:29:16,356 --> 00:29:21,996 Speaker 1: the line here. You know, the honest answer to that 457 00:29:22,116 --> 00:29:27,796 Speaker 1: question is, I don't know. People work in different ways. 458 00:29:28,836 --> 00:29:34,676 Speaker 1: Some people have beliefs that they think that that is 459 00:29:35,156 --> 00:29:42,196 Speaker 1: how nature works, and they relentlessly pursue demonstrating the physical 460 00:29:42,276 --> 00:29:49,436 Speaker 1: reality of their beliefs. Others just take the mathematical equations 461 00:29:49,436 --> 00:29:54,156 Speaker 1: and follow them and see where they lead. And you 462 00:29:54,196 --> 00:29:58,996 Speaker 1: see yourself in the latter camp. I'm somewhere in between. 463 00:29:59,196 --> 00:30:03,196 Speaker 1: I have things I believe in, but I pride myself 464 00:30:04,156 --> 00:30:08,076 Speaker 1: in being ready to drop my beliefs when they don't 465 00:30:08,116 --> 00:30:11,796 Speaker 1: measure up to the equation. The equations are the final arbiters. 466 00:30:11,836 --> 00:30:14,516 Speaker 1: The equations and the experiments are the final arbiters of 467 00:30:14,556 --> 00:30:21,796 Speaker 1: truth in our field, and many people have, including you 468 00:30:21,836 --> 00:30:27,796 Speaker 1: know Einstein. Einstein had very strong beliefs about how things 469 00:30:28,316 --> 00:30:35,156 Speaker 1: should be should be, and that got him through special relativity, 470 00:30:35,276 --> 00:30:40,316 Speaker 1: general relativity, and the beginnings of quantum mechanics. But then 471 00:30:40,396 --> 00:30:43,876 Speaker 1: he had beliefs about the way the world should be 472 00:30:44,636 --> 00:30:47,876 Speaker 1: that were being countermanded that we're being own by his 473 00:30:47,956 --> 00:30:51,756 Speaker 1: own equations, and then the experiments that were validating those equations, 474 00:30:51,796 --> 00:30:56,276 Speaker 1: and that reduced his his his productivity. M He did 475 00:30:56,316 --> 00:30:59,196 Speaker 1: pretty well, He did pretty well. Then he did pretty well. 476 00:30:59,236 --> 00:31:01,596 Speaker 1: But at some point he believed things that weren't true. 477 00:31:01,756 --> 00:31:05,196 Speaker 1: He believed that quantum mechanics was wrong. He believed their 478 00:31:05,196 --> 00:31:08,276 Speaker 1: word black holes, he believed their word gravity weight. You know, 479 00:31:08,316 --> 00:31:11,836 Speaker 1: he had some raw beef, wrong beliefs that he got 480 00:31:11,836 --> 00:31:14,556 Speaker 1: stuck on. So it interfered with his being able to 481 00:31:14,596 --> 00:31:16,636 Speaker 1: move on to make the next set of He might 482 00:31:16,676 --> 00:31:18,796 Speaker 1: have come up with even more fundamental things if he 483 00:31:18,796 --> 00:31:21,196 Speaker 1: had been able to keep on pushing. That's right, that's right. 484 00:31:21,316 --> 00:31:24,196 Speaker 1: So that's an argument that you may need some beliefs 485 00:31:24,196 --> 00:31:26,516 Speaker 1: to get you started. Yeah, but there needs to be 486 00:31:26,556 --> 00:31:28,756 Speaker 1: some kind of a reflective equilibrium where at some point 487 00:31:28,796 --> 00:31:32,316 Speaker 1: you have to start believing your equations. Yeah, you know, 488 00:31:32,596 --> 00:31:39,196 Speaker 1: it's always a conflict between sticking with what you believe 489 00:31:39,236 --> 00:31:44,756 Speaker 1: in and not giving up, and being too stubborn and 490 00:31:44,876 --> 00:31:47,916 Speaker 1: not being flexible enough. The real truth is it takes 491 00:31:47,956 --> 00:31:51,516 Speaker 1: all types. You know, there's some people who have an 492 00:31:51,556 --> 00:31:58,996 Speaker 1: idea and pursue it in the face of unreasonable hardship 493 00:31:59,036 --> 00:32:02,556 Speaker 1: and difficulty, and everybody's saying no, and everybody's saying no, 494 00:32:03,196 --> 00:32:04,956 Speaker 1: and some of those people turn out to be right. 495 00:32:04,996 --> 00:32:07,476 Speaker 1: Now people turn out to be right, but most of 496 00:32:07,476 --> 00:32:10,916 Speaker 1: them fall by the way side. Yeah, you need some 497 00:32:10,996 --> 00:32:14,436 Speaker 1: of You need people with unreasonable beliefs. You need people 498 00:32:14,596 --> 00:32:16,836 Speaker 1: who are ready to drop their beliefs. You know, it 499 00:32:16,836 --> 00:32:19,956 Speaker 1: takes a village. Let me ask a final question about 500 00:32:20,636 --> 00:32:24,436 Speaker 1: how these different pathways to understanding the world are going 501 00:32:24,436 --> 00:32:27,836 Speaker 1: to play out in the black hole context. Yea. When 502 00:32:27,836 --> 00:32:31,076 Speaker 1: you started working on black holes, as you said, there 503 00:32:31,196 --> 00:32:33,156 Speaker 1: was still a view among lots of people that there 504 00:32:33,196 --> 00:32:36,196 Speaker 1: were no such things right, and now we're in a 505 00:32:36,356 --> 00:32:40,196 Speaker 1: very different place. We've seen one. Yeah, does that take 506 00:32:40,596 --> 00:32:43,516 Speaker 1: some of the thrill out of it? Does it seem 507 00:32:44,316 --> 00:32:47,116 Speaker 1: you know? I mean, it's nice to be right, But 508 00:32:47,316 --> 00:32:50,156 Speaker 1: there seems like there's a stage of, as you said, 509 00:32:50,836 --> 00:32:54,916 Speaker 1: great observational astronomy in the space of black holes, which 510 00:32:54,956 --> 00:32:58,236 Speaker 1: is important and will expand our knowledge and maybe give 511 00:32:58,316 --> 00:33:01,836 Speaker 1: us radically new ideas about the world. But somehow seems 512 00:33:01,876 --> 00:33:04,836 Speaker 1: to be confirmatory of what you and others predicted and 513 00:33:05,036 --> 00:33:07,876 Speaker 1: what is actually now believed to be true. Is there 514 00:33:07,916 --> 00:33:11,596 Speaker 1: some it takes. I mean it's thrilling now, but ten 515 00:33:11,676 --> 00:33:13,476 Speaker 1: years from now, will some of the thrill will be 516 00:33:13,556 --> 00:33:18,476 Speaker 1: gone in working on something which everyone acknowledges exists. No, 517 00:33:20,436 --> 00:33:23,516 Speaker 1: I think it's only getting more interesting. We can think 518 00:33:23,596 --> 00:33:27,876 Speaker 1: of this. The last few years, or this observation even 519 00:33:28,396 --> 00:33:31,316 Speaker 1: is kind of a historical marker. You know, a hundred 520 00:33:31,356 --> 00:33:37,236 Speaker 1: years ago the existence of black holes was predicted. Now 521 00:33:37,316 --> 00:33:42,116 Speaker 1: they've been seen in the most straightforward way. So going 522 00:33:42,196 --> 00:33:46,596 Speaker 1: forward there will be better and better observations. But we 523 00:33:46,716 --> 00:33:53,116 Speaker 1: still have this huge puzzle. Yeah, the godon Can experient. 524 00:33:53,236 --> 00:33:56,436 Speaker 1: What is the result of the Godonkan experiment? What's coming 525 00:33:56,436 --> 00:34:00,196 Speaker 1: out of the black hole? Or equivalently, what is inside 526 00:34:00,196 --> 00:34:04,676 Speaker 1: the black hole? Then you know there's a fundamental contradiction 527 00:34:04,756 --> 00:34:08,396 Speaker 1: in the laws of physics as we currently understand them. 528 00:34:08,436 --> 00:34:10,836 Speaker 1: So that's what makes it so exciting. Something has to give. 529 00:34:10,956 --> 00:34:14,116 Speaker 1: It's that the thought experiment poses a contradiction between different 530 00:34:14,116 --> 00:34:17,716 Speaker 1: things that we're we are committed to. All the things 531 00:34:17,836 --> 00:34:21,836 Speaker 1: that we believe to be true. Can't all be true. 532 00:34:22,356 --> 00:34:26,236 Speaker 1: Something which we are completely at this moment unwilling to 533 00:34:26,276 --> 00:34:32,156 Speaker 1: give up as a truth about the universe must actually 534 00:34:32,196 --> 00:34:36,796 Speaker 1: be wrong, and the fact that that contradictions was recognized 535 00:34:36,916 --> 00:34:40,356 Speaker 1: forty years ago by Hawking and has sat there. As 536 00:34:40,356 --> 00:34:43,076 Speaker 1: the years have gone by, the longer it's sat there, 537 00:34:43,436 --> 00:34:47,476 Speaker 1: the more that we've realized what central importance it is. 538 00:34:48,196 --> 00:34:54,996 Speaker 1: So somehow the observational astronomy world and the theoretical physics 539 00:34:54,996 --> 00:35:00,876 Speaker 1: worlds have converged on black holes as the most interesting 540 00:35:00,916 --> 00:35:07,796 Speaker 1: and things around and it is. I'm pretty confident that well, 541 00:35:07,796 --> 00:35:11,036 Speaker 1: first of all, I there's no reason we can't ultimately 542 00:35:11,076 --> 00:35:14,876 Speaker 1: solve this problem. And the fact that it has sat 543 00:35:14,956 --> 00:35:19,596 Speaker 1: there for so long, I think there is a consensus 544 00:35:19,636 --> 00:35:24,956 Speaker 1: in the community that we can't solve the problem without 545 00:35:24,996 --> 00:35:29,716 Speaker 1: a fundamental new insight into the structure of the universe 546 00:35:30,276 --> 00:35:36,836 Speaker 1: at the same revolutionary level as quantum mechanics or relativity. 547 00:35:36,876 --> 00:35:39,556 Speaker 1: That it's not a technical problem that we missed a 548 00:35:39,636 --> 00:35:42,476 Speaker 1: factor of two somewhere. So that's the holy grail. That 549 00:35:42,916 --> 00:35:48,556 Speaker 1: is the holy grail. It's an exciting thing that black 550 00:35:48,596 --> 00:35:53,276 Speaker 1: holes have become come to center stage and observational astronomy 551 00:35:53,556 --> 00:35:57,396 Speaker 1: at the same time as in theoretical physics. We don't 552 00:35:57,516 --> 00:36:00,276 Speaker 1: have a roadmap how we're going to talk to each 553 00:36:00,276 --> 00:36:05,276 Speaker 1: other and close that gap. But we're thinking here on 554 00:36:05,276 --> 00:36:07,556 Speaker 1: a hundred year time scale, we might not even have 555 00:36:07,596 --> 00:36:10,396 Speaker 1: found the city where the whole grail is hidden, but 556 00:36:10,436 --> 00:36:13,036 Speaker 1: we've maybe found the continent, and now we're gonna have 557 00:36:13,036 --> 00:36:15,836 Speaker 1: to keep exploring. But it's a pretty big deal to 558 00:36:15,916 --> 00:36:18,396 Speaker 1: have found the continent. That's a big deal to have 559 00:36:18,396 --> 00:36:20,876 Speaker 1: found the kind we know where we're looking and now. 560 00:36:21,036 --> 00:36:23,076 Speaker 1: And I think you know, Although I'm loath to draw 561 00:36:23,156 --> 00:36:28,036 Speaker 1: too many non physics metaphoric conclusion from physics, the idea 562 00:36:28,076 --> 00:36:31,316 Speaker 1: that sometimes we're in the grips of contradictory views and 563 00:36:31,396 --> 00:36:34,676 Speaker 1: something's got to give, we need some new account to 564 00:36:34,716 --> 00:36:36,916 Speaker 1: make it work out is about as good a lesson 565 00:36:37,236 --> 00:36:40,876 Speaker 1: to take away from black Holes as I can imagine. Andy, 566 00:36:40,916 --> 00:36:43,596 Speaker 1: thank you so so much for your for your brilliant 567 00:36:43,596 --> 00:36:51,436 Speaker 1: thoughts in your time. Thank you Eddie, thank you Noah. 568 00:36:51,796 --> 00:36:53,916 Speaker 1: When I see an image like the image of the 569 00:36:53,956 --> 00:36:58,516 Speaker 1: black hole, I'm filled with wonderment. The mere accomplishment of 570 00:36:58,596 --> 00:37:01,116 Speaker 1: human beings, to be able to see something so far away, 571 00:37:01,476 --> 00:37:03,956 Speaker 1: to conceive of it, to make sense of it. That's 572 00:37:03,956 --> 00:37:05,876 Speaker 1: the kind of thing that really hits me where I live. 573 00:37:05,996 --> 00:37:09,796 Speaker 1: It makes me believe that being human is actually worth something. 574 00:37:09,876 --> 00:37:13,556 Speaker 1: After all, we can actually know things and achieve connection. 575 00:37:14,396 --> 00:37:16,956 Speaker 1: But you know what, when I listen to Andy, somebody 576 00:37:16,956 --> 00:37:19,676 Speaker 1: who actually understands at the most profound level what these 577 00:37:19,676 --> 00:37:23,116 Speaker 1: discoveries are, I'm even more struck by the wonderment that 578 00:37:23,276 --> 00:37:26,636 Speaker 1: he feels than the wonderment that I feel. He's not 579 00:37:26,756 --> 00:37:30,516 Speaker 1: jaded at all. He spent a lifetime working on black holes, 580 00:37:30,636 --> 00:37:33,276 Speaker 1: and to him, where at the crossroads of excitement where 581 00:37:33,316 --> 00:37:37,036 Speaker 1: things are only going to keep on getting better. That's 582 00:37:37,116 --> 00:37:42,996 Speaker 1: genuine scientific exploration. That's genuine scientific collegiality and collaboration like 583 00:37:43,036 --> 00:37:46,036 Speaker 1: the kind that Andy has done with Stephen Hawking. And 584 00:37:46,116 --> 00:37:48,156 Speaker 1: it makes you think not just that the universe is 585 00:37:48,156 --> 00:37:52,396 Speaker 1: an amazing place, but maybe we at our best when 586 00:37:52,396 --> 00:37:55,116 Speaker 1: we're not fighting and we're searching for the truth. Are 587 00:37:55,116 --> 00:38:03,396 Speaker 1: in such bad people? After all? Deep Background is brought 588 00:38:03,396 --> 00:38:06,596 Speaker 1: to you by Pushkin Industries. Our producer is Lydia Geane Coott, 589 00:38:06,676 --> 00:38:10,796 Speaker 1: with engineering by Jason Gambrell and Jasonstkowski. Our showrunner is 590 00:38:10,796 --> 00:38:13,836 Speaker 1: Sophie mckibbon. Our theme music is composed by Luis GERA 591 00:38:14,396 --> 00:38:17,876 Speaker 1: special thanks to the Pushkin Brass Malcolm Gladwell, Jacob Weisberg 592 00:38:17,876 --> 00:38:20,676 Speaker 1: and Mia Lobel. I'm Noah Feldman. You can follow me 593 00:38:20,716 --> 00:38:24,316 Speaker 1: on Twitter at Noah R. Feldman. This is deep background