1 00:00:00,000 --> 00:00:03,417 (light electronic music) 2 00:00:09,610 --> 00:00:10,520 - Hi, everyone. 3 00:00:10,520 --> 00:00:13,450 Welcome to Conversations at the Perimeter. 4 00:00:13,450 --> 00:00:16,190 Today, Colin and I are so excited to bring you 5 00:00:16,190 --> 00:00:18,940 this conversation with Carlo Rovelli. 6 00:00:18,940 --> 00:00:20,960 Carlo is a theoretical physicist, 7 00:00:20,960 --> 00:00:24,130 with expertise in both physics and philosophy, 8 00:00:24,130 --> 00:00:27,120 and his research interests include loop quantum gravity, 9 00:00:27,120 --> 00:00:28,230 the nature of time, 10 00:00:28,230 --> 00:00:31,210 and the relational interpretation of quantum theory. 11 00:00:31,210 --> 00:00:33,230 - And Carlo is also a bestselling author 12 00:00:33,230 --> 00:00:34,720 of popular science books. 13 00:00:34,720 --> 00:00:37,090 His "Seven Brief Lessons on Physics" 14 00:00:37,090 --> 00:00:40,340 was a breakout success, sold more than a million copies, 15 00:00:40,340 --> 00:00:43,010 has been translated into more than 40 languages. 16 00:00:43,010 --> 00:00:44,340 I've been a fan for years, 17 00:00:44,340 --> 00:00:46,180 so it was just a thrill for me to talk to him, 18 00:00:46,180 --> 00:00:47,500 not just about his research, 19 00:00:47,500 --> 00:00:50,020 but how and why he translates 20 00:00:50,020 --> 00:00:52,560 these difficult scientific topics into concepts 21 00:00:52,560 --> 00:00:54,110 that people like me can understand. 22 00:00:54,110 --> 00:00:55,900 - He also has some other great books 23 00:00:55,900 --> 00:00:58,270 called "Reality Is Not What It Seems", 24 00:00:58,270 --> 00:01:00,240 there's also "The Order of Time", 25 00:01:00,240 --> 00:01:03,950 and "Helgoland: Making Sense of the Quantum Revolution". 26 00:01:03,950 --> 00:01:05,990 And he has another new book coming out 27 00:01:05,990 --> 00:01:08,470 called "There are Places in the World Where Rules 28 00:01:08,470 --> 00:01:10,390 Are Less Important than Kindness: 29 00:01:10,390 --> 00:01:13,227 And Other Thoughts on Physics, Philosophy, and The World", 30 00:01:13,227 --> 00:01:15,610 and I have to say, I just love the title 31 00:01:15,610 --> 00:01:17,730 of this upcoming book, and I can't wait to read it. 32 00:01:17,730 --> 00:01:20,180 - And I loved this conversation that we had with Carlos, 33 00:01:20,180 --> 00:01:21,504 so let's have a listen. 34 00:01:21,504 --> 00:01:25,550 (light electronic music) 35 00:01:25,550 --> 00:01:28,650 Thank you for joining us, it's lovely to have you here. 36 00:01:28,650 --> 00:01:31,300 - Thank you, it's wonderful finally being back 37 00:01:31,300 --> 00:01:33,900 at the PI after this long absence. 38 00:01:33,900 --> 00:01:36,880 - I was struggling with ways to introduce you 39 00:01:36,880 --> 00:01:38,567 to our audience because there are so many things, 40 00:01:38,567 --> 00:01:41,050 you know, theoretical physicist, and author, 41 00:01:41,050 --> 00:01:42,570 and world traveler, and philosopher, 42 00:01:42,570 --> 00:01:44,480 so I decided I didn't want to introduce you. 43 00:01:44,480 --> 00:01:46,590 Pretend I'm a stranger on a plane and I've just sat down 44 00:01:46,590 --> 00:01:48,127 next to you, and I've buckled up, and I say, 45 00:01:48,127 --> 00:01:49,750 "Hey, what do you do for a living?" 46 00:01:49,750 --> 00:01:52,130 - I would say, "Hi, my name is Carlo. 47 00:01:52,130 --> 00:01:56,057 I was born in Italy, and I go around and talk with people. 48 00:01:56,057 --> 00:01:58,320 I have ideas, I try to do them. 49 00:01:58,320 --> 00:01:59,262 What about you?" 50 00:01:59,262 --> 00:02:01,350 - (laughs) I talk to people like you, 51 00:02:01,350 --> 00:02:03,190 trying to figure out what they do, so it's a good thing 52 00:02:03,190 --> 00:02:05,760 we sat next to each other on this plane. 53 00:02:05,760 --> 00:02:08,290 You didn't mention theoretical physics. 54 00:02:08,290 --> 00:02:10,330 Is that because what you consider 55 00:02:10,330 --> 00:02:12,560 yourself doing is more just talking to people 56 00:02:12,560 --> 00:02:14,320 about a variety of subjects? - No, if you have 57 00:02:14,320 --> 00:02:16,740 to define me, what I am primarily, 58 00:02:16,740 --> 00:02:18,670 I'm definitely a theoretical physicist. 59 00:02:18,670 --> 00:02:21,160 The rest of the things that I do are part motivating, 60 00:02:21,160 --> 00:02:22,440 part around that. 61 00:02:22,440 --> 00:02:24,450 My competency, if I have any, 62 00:02:24,450 --> 00:02:26,120 it's in theoretical physics. 63 00:02:26,120 --> 00:02:29,120 I don't like to define myself, even in front of myself. 64 00:02:29,120 --> 00:02:31,000 I like to keep things open. 65 00:02:31,000 --> 00:02:34,020 And when I started writing books for the large public, 66 00:02:34,020 --> 00:02:35,757 there was a moment in which I was telling myself, 67 00:02:35,757 --> 00:02:38,600 "Wait a moment, are you just turning into a writer 68 00:02:38,600 --> 00:02:40,580 instead of a scientist," 69 00:02:40,580 --> 00:02:44,300 and then I realized that this is a meaningless question. 70 00:02:44,300 --> 00:02:47,570 I'm just doing what I'm doing, and things are connected. 71 00:02:47,570 --> 00:02:50,450 The only meaningful question is how many hours I devote 72 00:02:50,450 --> 00:02:52,260 for one and the other, that might be it. 73 00:02:52,260 --> 00:02:54,630 - I ask partly because you're currently, 74 00:02:54,630 --> 00:02:56,580 you have a position in London, Ontario, 75 00:02:56,580 --> 00:02:58,920 at the Rotman School of Philosophy, 76 00:02:58,920 --> 00:03:01,300 which seems, at least on the surface, 77 00:03:01,300 --> 00:03:04,297 to be a strange place for a theoretical physicist to be. 78 00:03:04,297 --> 00:03:07,481 Can you explain what you're doing at a school of philosophy? 79 00:03:07,481 --> 00:03:09,910 - (chuckles) I talk with philosophers. 80 00:03:09,910 --> 00:03:11,680 I love to talk with philosophers 81 00:03:11,680 --> 00:03:14,220 because I think it's useful for physics. 82 00:03:14,220 --> 00:03:17,630 I have this convention since a long time. 83 00:03:17,630 --> 00:03:20,060 I've been interested in philosophy since I was a kid. 84 00:03:20,060 --> 00:03:21,840 When I was a student studying physics, 85 00:03:21,840 --> 00:03:24,290 I also continued to study philosophy, 86 00:03:24,290 --> 00:03:28,650 and I think that a clear-cut separation is a bit artificial 87 00:03:28,650 --> 00:03:31,730 and is damaging for both disciplines. 88 00:03:31,730 --> 00:03:33,020 - How so? 89 00:03:33,020 --> 00:03:36,100 - Not all physics needs to talk with philosophy. 90 00:03:36,100 --> 00:03:38,400 If you have to solve the Maxwell's equations 91 00:03:38,400 --> 00:03:41,470 for a certain antenna, you just happily ignore philosophers, 92 00:03:41,470 --> 00:03:43,890 and a lot of physics is just concrete, 93 00:03:43,890 --> 00:03:45,560 specific problems. - Right. 94 00:03:45,560 --> 00:03:47,580 - But, of course, there's a part of physics which is not 95 00:03:47,580 --> 00:03:51,430 to apply knowledge that we have for solving problems, 96 00:03:51,430 --> 00:03:55,254 it's to find out what is the knowledge we have at the basis, 97 00:03:55,254 --> 00:03:57,550 and that part, it's the kind of things that, you know, 98 00:03:57,550 --> 00:04:00,320 Einstein, Maxwell, or Newton, or Galileo, 99 00:04:00,320 --> 00:04:02,970 or Boltzmann were doing, or Heisenberg, 100 00:04:02,970 --> 00:04:05,930 and that kind of activity, traditionally, 101 00:04:05,930 --> 00:04:08,630 was done by people who were schooled in philosophy. 102 00:04:08,630 --> 00:04:11,940 I mean, Einstein had a deep knowledge of philosophy, 103 00:04:11,940 --> 00:04:14,330 and so Heisenberg, and certainly Newton. 104 00:04:14,330 --> 00:04:17,510 Galileo, he was an avid reader of Aristotle. 105 00:04:17,510 --> 00:04:19,490 There's a mistake in the understanding 106 00:04:19,490 --> 00:04:21,190 of physics, and science in general. 107 00:04:21,190 --> 00:04:23,050 Science is just collecting data 108 00:04:23,050 --> 00:04:25,410 and writing equations that predict this data. 109 00:04:25,410 --> 00:04:27,960 I mean, that's just a little part of it. 110 00:04:27,960 --> 00:04:31,830 The largest part of it is figuring out 111 00:04:31,830 --> 00:04:35,590 a set of notions, concepts, a conceptual structure, 112 00:04:35,590 --> 00:04:37,200 how to think about that. 113 00:04:37,200 --> 00:04:38,810 When you go from, you know, 114 00:04:38,810 --> 00:04:41,230 the Ptolemaic to the Copernican system, 115 00:04:41,230 --> 00:04:43,880 you don't just collect data, you rearrange the order 116 00:04:43,880 --> 00:04:45,220 of the world in a different way. 117 00:04:45,220 --> 00:04:46,053 That's what Einstein did, 118 00:04:46,053 --> 00:04:47,130 that's what Maxwell and Faraday did, 119 00:04:47,130 --> 00:04:50,470 that's what Heisenberg did, and Boltzmann, and so on. 120 00:04:50,470 --> 00:04:54,910 So, the core problems in fundamental physics today, 121 00:04:54,910 --> 00:04:57,140 like quantum gravity, the problem in which I am, 122 00:04:57,140 --> 00:05:00,330 do require the same kind of rethinking 123 00:05:00,330 --> 00:05:02,240 the conceptual basis of a discipline, 124 00:05:02,240 --> 00:05:03,850 and the philosophers are very good in that, 125 00:05:03,850 --> 00:05:06,520 not because they solve the problem of physics. 126 00:05:06,520 --> 00:05:08,043 I mean, relativity was found by Einstein, 127 00:05:08,043 --> 00:05:10,600 who was a physicist, but he's a physicist who was listening 128 00:05:10,600 --> 00:05:12,750 to what the philosophers were saying. 129 00:05:12,750 --> 00:05:15,810 Philosophy has a capacity of critical thinking, 130 00:05:15,810 --> 00:05:19,580 which is very deep, has imagination. 131 00:05:19,580 --> 00:05:21,110 Philosophers come out with completely different ways 132 00:05:21,110 --> 00:05:23,560 of thinking about reality, sometimes crazy, 133 00:05:23,560 --> 00:05:25,270 and we don't care about them, but that's not the point, 134 00:05:25,270 --> 00:05:27,070 sometimes very useful. - Sometimes I think 135 00:05:27,070 --> 00:05:29,220 theoretical physicists come up with ideas of reality 136 00:05:29,220 --> 00:05:30,900 that strike me as crazy too. 137 00:05:30,900 --> 00:05:33,231 - Sometimes they do, sometimes even perhaps too much crazy, 138 00:05:33,231 --> 00:05:35,127 and they should listen to philosophers who say, 139 00:05:35,127 --> 00:05:37,250 "Wait, come on, don't exaggerate, guys." 140 00:05:37,250 --> 00:05:40,110 - Are there certain open questions in physics 141 00:05:40,110 --> 00:05:41,870 that you think would most benefit 142 00:05:41,870 --> 00:05:44,033 from input from philosophers? 143 00:05:45,000 --> 00:05:47,500 - Yes, and they change, of course, 144 00:05:47,500 --> 00:05:51,190 because physics is a process, and right now, 145 00:05:51,190 --> 00:05:54,840 the number of open questions where philosophical thinking 146 00:05:54,840 --> 00:05:56,880 and philosophical clarity is useful, 147 00:05:56,880 --> 00:05:59,650 some of them, for instance, have to do with time. 148 00:05:59,650 --> 00:06:01,830 In trying to write a quantum theory of gravity, 149 00:06:01,830 --> 00:06:03,670 of course, space and time have to change 150 00:06:03,670 --> 00:06:05,540 because now we're looking at the quantum property 151 00:06:05,540 --> 00:06:06,560 of space and time. 152 00:06:06,560 --> 00:06:11,016 We have so many prejudices about how space 153 00:06:11,016 --> 00:06:13,470 should be and how time should be. 154 00:06:13,470 --> 00:06:17,220 A careful philosophical analysis of what we know, 155 00:06:17,220 --> 00:06:21,690 I find it useful, even in simple things. 156 00:06:21,690 --> 00:06:24,490 One very well-known problem about time 157 00:06:24,490 --> 00:06:27,430 is that the past is different from the future, 158 00:06:27,430 --> 00:06:28,970 and so, what's the root 159 00:06:28,970 --> 00:06:31,010 of this difference between past and future? 160 00:06:31,010 --> 00:06:34,550 Is that something intrinsic in time itself, or not? 161 00:06:34,550 --> 00:06:36,560 And the answer is not just academic. 162 00:06:36,560 --> 00:06:37,700 Well, yeah, it is academic, 163 00:06:37,700 --> 00:06:40,590 but (chuckles) the question is important 164 00:06:40,590 --> 00:06:41,990 because if we want to understand more, 165 00:06:41,990 --> 00:06:44,060 understand how quantum gravity works, 166 00:06:44,060 --> 00:06:46,400 we have to get clarity about these things. 167 00:06:46,400 --> 00:06:49,380 The nature of observer is another one. 168 00:06:49,380 --> 00:06:52,260 We now are in this funny situation with quantum mechanics, 169 00:06:52,260 --> 00:06:53,910 which is a fantastically good theory, 170 00:06:53,910 --> 00:06:57,010 but it's formulated in terms of an observer. 171 00:06:57,010 --> 00:06:57,843 So, why? 172 00:06:57,843 --> 00:07:00,170 Do we need a guy with a PhD in physics 173 00:07:00,170 --> 00:07:02,010 to understand how the things work? 174 00:07:02,010 --> 00:07:04,580 No, I mean, things work by themself, without an observer, 175 00:07:04,580 --> 00:07:05,787 so how to make sense of that, 176 00:07:05,787 --> 00:07:08,040 and these are questions that physicists 177 00:07:08,040 --> 00:07:10,170 have been struggling with, and they are, 178 00:07:10,170 --> 00:07:11,630 and they will come up with a solution. 179 00:07:11,630 --> 00:07:14,170 I think solutions are being debated around the table. 180 00:07:14,170 --> 00:07:16,580 Philosophers can listen, contribute, 181 00:07:16,580 --> 00:07:18,380 and provide perspective. 182 00:07:18,380 --> 00:07:19,387 - I have your book here, 183 00:07:19,387 --> 00:07:22,330 "Reality Is Not What It Seems", about quantum gravity, 184 00:07:22,330 --> 00:07:23,990 and we'll get more into quantum gravity, 185 00:07:23,990 --> 00:07:28,140 but what struck me most was the book essentially begins 186 00:07:28,140 --> 00:07:29,220 with the ancient Greeks. 187 00:07:29,220 --> 00:07:30,820 Quantum gravity and loop quantum gravity 188 00:07:30,820 --> 00:07:32,640 are relatively new fields of physics, 189 00:07:32,640 --> 00:07:35,220 but to explain them, you went back thousands of years. 190 00:07:35,220 --> 00:07:38,070 What inspired you to go so far back 191 00:07:38,070 --> 00:07:40,483 to bring us to the present of quantum gravity? 192 00:07:41,577 --> 00:07:43,030 - "Reality Is Not What It Seems", 193 00:07:43,030 --> 00:07:44,650 it's actually the first popular book 194 00:07:44,650 --> 00:07:45,980 that I wrote about science. 195 00:07:45,980 --> 00:07:50,697 I wrote it quite late, after so many people had told me, 196 00:07:50,697 --> 00:07:53,240 "Why don't you write a popular book about quantum gravity?" 197 00:07:53,240 --> 00:07:55,680 It was at least 20 years that people were telling me that, 198 00:07:55,680 --> 00:07:57,537 and pushing, and some publishers also, 199 00:07:57,537 --> 00:07:59,850 like, "Come on, Carlo, you have 200 00:07:59,850 --> 00:08:01,610 this beautiful science, why don't you write about that?" 201 00:08:01,610 --> 00:08:04,250 Also because people were sick and tired with string theory, 202 00:08:04,250 --> 00:08:06,150 I mean, just can't stand string theory anymore, 203 00:08:06,150 --> 00:08:08,120 so let's do some good quantum gravity. 204 00:08:08,120 --> 00:08:09,640 But I didn't know how to do it, 205 00:08:09,640 --> 00:08:13,030 because how do you tell quantum gravity to people, right? 206 00:08:13,030 --> 00:08:14,787 I mean, you have to digest general relativity, 207 00:08:14,787 --> 00:08:18,660 you have to digest quantum mechanics, so it's a long story. 208 00:08:18,660 --> 00:08:20,897 For long, I hesitated because I wanted to do physics 209 00:08:20,897 --> 00:08:22,560 and not waste time writing. 210 00:08:22,560 --> 00:08:24,860 Then I started considering the idea, 211 00:08:24,860 --> 00:08:27,050 but I couldn't find the right way, 212 00:08:27,050 --> 00:08:28,920 and then there was a flash. 213 00:08:28,920 --> 00:08:31,730 I had so many things to do, but I couldn't organize them. 214 00:08:31,730 --> 00:08:33,950 I mentioned, in one of the prefaces of my books, 215 00:08:33,950 --> 00:08:35,490 and I don't remember which edition, 216 00:08:35,490 --> 00:08:38,150 I was driving from Italy to France, 217 00:08:38,150 --> 00:08:41,320 where I had moved at the time, in the middle of the night. 218 00:08:41,320 --> 00:08:43,257 And then I said, "Well, I need to explain this concept, 219 00:08:43,257 --> 00:08:44,690 I need to explain this concept, 220 00:08:44,690 --> 00:08:45,920 I need to explain this concept." 221 00:08:45,920 --> 00:08:47,240 I need to tell the reader 222 00:08:47,240 --> 00:08:48,983 what is a field, an electric field. 223 00:08:48,983 --> 00:08:50,160 It's not clear. 224 00:08:50,160 --> 00:08:52,640 I need to tell the reader what exactly we mean by geometry. 225 00:08:52,640 --> 00:08:53,473 It's subtle. 226 00:08:53,473 --> 00:08:55,800 I need to tell the reader that particles 227 00:08:55,800 --> 00:08:57,500 are not precisely particles, 228 00:08:57,500 --> 00:08:59,760 so there's some discreteness, there's some granularity. 229 00:08:59,760 --> 00:09:01,580 And then I started thinking, well, 230 00:09:01,580 --> 00:09:04,040 maybe I should say when these ideas were born, 231 00:09:04,040 --> 00:09:06,330 so the ideas needed to understand, 232 00:09:06,330 --> 00:09:07,980 if I tell how they were born, 233 00:09:07,980 --> 00:09:11,800 and suddenly the entire history, the narration, 234 00:09:11,800 --> 00:09:13,100 came in front of my mind. 235 00:09:13,100 --> 00:09:16,280 I said, "Of course, I just talk about Democritus." 236 00:09:16,280 --> 00:09:17,660 - Right. - I talk about Galileo, 237 00:09:17,660 --> 00:09:19,510 I talk about Faraday, I talk about Maxwell, 238 00:09:19,510 --> 00:09:22,420 what problems they were addressing, 239 00:09:22,420 --> 00:09:25,410 how they came out with that particular solution, 240 00:09:25,410 --> 00:09:28,000 and why we're using this notion now, 241 00:09:28,000 --> 00:09:30,550 and how this notion built up, changed, 242 00:09:30,550 --> 00:09:32,589 and came all the way to a point of reality. 243 00:09:32,589 --> 00:09:36,080 No, and this is the evolution of the world. 244 00:09:36,080 --> 00:09:37,070 In the Renaissance, 245 00:09:37,070 --> 00:09:39,370 there's this idea that this is res extensa. 246 00:09:39,370 --> 00:09:40,927 Then Newton comes and says, 247 00:09:40,927 --> 00:09:44,050 "Okay, I go out the world, it's space, time passes, 248 00:09:44,050 --> 00:09:45,910 and there are some little stones 249 00:09:45,910 --> 00:09:47,340 that move around with forces." 250 00:09:47,340 --> 00:09:48,930 And then Faraday comes, "Wait, wait, wait, 251 00:09:48,930 --> 00:09:50,710 you're missing something, there's a field," 252 00:09:50,710 --> 00:09:53,010 okay, and Maxwell put the order in the field. 253 00:09:53,010 --> 00:09:54,417 And then, Einstein comes and says, 254 00:09:54,417 --> 00:09:57,770 "Look, the space and the time are actually mixed, 255 00:09:57,770 --> 00:09:59,480 so you should not have two different things. 256 00:09:59,480 --> 00:10:00,800 You should- - Spacetime. 257 00:10:00,800 --> 00:10:04,020 - Spacetime, and then I instantaneously realized 258 00:10:04,020 --> 00:10:06,490 that spacetime is a field. 259 00:10:06,490 --> 00:10:08,380 Wow, okay, now we connect the notion 260 00:10:08,380 --> 00:10:09,577 of field with spacetime, 261 00:10:09,577 --> 00:10:11,620 and quantum mechanics connect the notion 262 00:10:11,620 --> 00:10:13,150 of a particle with a field. 263 00:10:13,150 --> 00:10:16,750 So, unless you go through the way that things developed, 264 00:10:16,750 --> 00:10:18,610 you don't get them, so I decided to write a book 265 00:10:18,610 --> 00:10:23,080 without details, but with the core flow of ideas. 266 00:10:23,080 --> 00:10:25,570 - When that epiphany hit you while driving, 267 00:10:25,570 --> 00:10:26,630 I know what happened after that. 268 00:10:26,630 --> 00:10:28,990 - You know what happened after that, I got a ticket. 269 00:10:28,990 --> 00:10:30,470 - Yeah, because you were driving too fast 270 00:10:30,470 --> 00:10:32,520 'cause you were- - I was driving too fast. 271 00:10:32,520 --> 00:10:35,470 It was an empty in the night highway. 272 00:10:35,470 --> 00:10:36,790 I was so excited, 273 00:10:36,790 --> 00:10:37,893 so excited. - You had the pedal 274 00:10:37,893 --> 00:10:39,210 to the metal. - Yes, the first chapter 275 00:10:39,210 --> 00:10:41,590 is gonna be saying this, and then (imitates siren). 276 00:10:42,803 --> 00:10:43,636 I said, "Shit," 277 00:10:43,636 --> 00:10:45,542 and then I looked at the speedometer or whatever, 278 00:10:45,542 --> 00:10:48,020 don't know how you call it in English, and I'm going, 279 00:10:48,020 --> 00:10:52,020 you know, 180 kilometers per hour on the highways. 280 00:10:52,020 --> 00:10:53,200 Oh, no. 281 00:10:53,200 --> 00:10:56,447 So, I had to pull on the side, and the policeman said, 282 00:10:56,447 --> 00:10:58,275 "What the hell are you doing," 283 00:10:58,275 --> 00:10:59,960 and I was, you know, I just told him. 284 00:10:59,960 --> 00:11:03,140 I said, "I'm sorry, I just was going extremely fast. 285 00:11:03,140 --> 00:11:05,450 The reality was I was not even in a hurry. 286 00:11:05,450 --> 00:11:09,200 I just got an idea how to write a book (chuckles) 287 00:11:09,200 --> 00:11:12,800 and was so happy with that, I just was excited, excited." 288 00:11:12,800 --> 00:11:14,120 And the policeman said, "Okay, good luck with your book," 289 00:11:14,120 --> 00:11:16,260 and let me go. - He let you go. 290 00:11:16,260 --> 00:11:19,024 I'm dying to use that excuse someday, you know. 291 00:11:19,024 --> 00:11:20,690 No, I was speeding because I figured out 292 00:11:20,690 --> 00:11:22,260 how to write a book about quantum gravity. 293 00:11:22,260 --> 00:11:23,760 I don't think it will work for me, 294 00:11:23,760 --> 00:11:25,460 but I'm glad it worked for you. 295 00:11:25,460 --> 00:11:27,577 - Yeah, it's good to know that works. (chuckles) 296 00:11:27,577 --> 00:11:28,930 I have a question. 297 00:11:28,930 --> 00:11:30,310 A lot of what you're talking about, 298 00:11:30,310 --> 00:11:32,490 it seems that it's very fundamental, 299 00:11:32,490 --> 00:11:34,970 this idea of unlearning things, 300 00:11:34,970 --> 00:11:36,500 both when you're writing a book, 301 00:11:36,500 --> 00:11:39,650 to encourage your readers to unlearn some things, 302 00:11:39,650 --> 00:11:41,170 or even in your research. 303 00:11:41,170 --> 00:11:43,410 I think that when we're thinking about something, 304 00:11:43,410 --> 00:11:45,930 we can be stuck in certain ways of conceptual thinking 305 00:11:45,930 --> 00:11:49,430 or be making some assumptions and not even realize it. 306 00:11:49,430 --> 00:11:51,830 Are there certain strategies that you've learned, 307 00:11:51,830 --> 00:11:53,430 perhaps from philosophers, 308 00:11:53,430 --> 00:11:55,750 that encourage you to challenge 309 00:11:55,750 --> 00:11:58,180 your conceptual ways of thinking? 310 00:11:58,180 --> 00:11:59,680 - Oh, that's a very good question. 311 00:11:59,680 --> 00:12:01,120 I don't know the answer. 312 00:12:01,120 --> 00:12:03,870 I think the most fundamental point about learning, 313 00:12:03,870 --> 00:12:06,260 that difficulty of learning is not to learn something new, 314 00:12:06,260 --> 00:12:08,170 that's easy, the difficulty of learning 315 00:12:08,170 --> 00:12:10,480 is to unlearn what we think we know. 316 00:12:10,480 --> 00:12:12,560 We are all deeply convinced that we are right 317 00:12:12,560 --> 00:12:14,370 about the way (chuckles) we see the world, 318 00:12:14,370 --> 00:12:15,650 everybody, including myself, 319 00:12:15,650 --> 00:12:19,300 so we just don't give up easily the ideas we have, 320 00:12:19,300 --> 00:12:21,472 and we don't learn unless we give up 321 00:12:21,472 --> 00:12:23,300 the ideas we have. - You wrote once that science 322 00:12:23,300 --> 00:12:25,500 is born from an act of humility. 323 00:12:25,500 --> 00:12:26,710 Is that true? - Yeah. 324 00:12:26,710 --> 00:12:27,730 Do you mean, by humility, 325 00:12:27,730 --> 00:12:31,220 the idea that we can accept that we don't know everything? 326 00:12:31,220 --> 00:12:32,700 - That, but even stronger. 327 00:12:32,700 --> 00:12:35,410 The idea that what we think we know, we might be wrong, 328 00:12:35,410 --> 00:12:38,540 and so what we don't know is so much more 329 00:12:38,540 --> 00:12:42,970 and so large that we shouldn't rely so much on what we know. 330 00:12:42,970 --> 00:12:43,803 Yeah, I think, humility, 331 00:12:43,803 --> 00:12:47,070 there is this beautiful letter by Newton. 332 00:12:47,070 --> 00:12:49,660 Newton was arrogant, pretentious, 333 00:12:49,660 --> 00:12:52,860 perfectly aware that he was the greatest thinker 334 00:12:52,860 --> 00:12:55,070 of his time, and three centuries later, 335 00:12:55,070 --> 00:12:56,770 we still think he's the greatest thinker, 336 00:12:56,770 --> 00:12:59,350 maybe in science, of all the times. 337 00:12:59,350 --> 00:13:00,560 He was aware of that, 338 00:13:00,560 --> 00:13:03,260 and at the end of his life, he writes this letter. 339 00:13:03,260 --> 00:13:05,270 He says, "I don't know how the others are looking at me 340 00:13:05,270 --> 00:13:08,000 or will be looking at me, but I myself look at myself 341 00:13:08,000 --> 00:13:12,110 like a kid playing with little pebbles on the shore 342 00:13:12,110 --> 00:13:15,440 in front of the ocean of our ignorance." 343 00:13:15,440 --> 00:13:17,900 That's why he succeeded in being Newton, I think, 344 00:13:17,900 --> 00:13:19,830 because he was perfectly aware 345 00:13:19,830 --> 00:13:22,300 that there was everything to be discovered. 346 00:13:22,300 --> 00:13:24,640 - So, he was both arrogant and humble 347 00:13:24,640 --> 00:13:25,948 at the same time. - Humble, exactly. 348 00:13:25,948 --> 00:13:27,750 Arrogant and humble, there's a mix, 349 00:13:27,750 --> 00:13:28,727 the mixture of the two. - Right. 350 00:13:28,727 --> 00:13:31,240 - You can be arrogant with respect to the others, 351 00:13:31,240 --> 00:13:33,607 humble with respect to your work and your ignorance, 352 00:13:33,607 --> 00:13:35,580 and the fact that we might be wrong. 353 00:13:35,580 --> 00:13:37,060 I've been reading this summer, 354 00:13:37,060 --> 00:13:39,590 because we're doing an audio book in English, 355 00:13:39,590 --> 00:13:41,480 Galileo's greatest book. 356 00:13:41,480 --> 00:13:44,640 It's the dialogue of the massive systems of the world. 357 00:13:44,640 --> 00:13:45,473 It's a fantastic book. 358 00:13:45,473 --> 00:13:48,000 It's a book that convinced humankind, in fact, 359 00:13:48,000 --> 00:13:49,720 that the earth is moving, spinning, 360 00:13:49,720 --> 00:13:51,340 and is going around the sun. 361 00:13:51,340 --> 00:13:53,370 It has all the arguments for the earth to move, 362 00:13:53,370 --> 00:13:56,190 but when reading it, a surprise is that the arguments 363 00:13:56,190 --> 00:13:57,503 are just a few pages. 364 00:13:57,503 --> 00:14:01,020 A large part of the book is to convince a reader 365 00:14:01,020 --> 00:14:05,900 that it's possible to question what he took for granted. 366 00:14:05,900 --> 00:14:07,990 It's all about, look, you think that, 367 00:14:07,990 --> 00:14:09,720 but that might not be right. 368 00:14:09,720 --> 00:14:11,650 It's only when, three quarters into the book, 369 00:14:11,650 --> 00:14:13,570 he said, okay, now you're open to the book, 370 00:14:13,570 --> 00:14:14,910 I haven't argued anything. 371 00:14:14,910 --> 00:14:16,730 Only at that point, he brings argument 372 00:14:16,730 --> 00:14:18,890 for the movement of the earth, 373 00:14:18,890 --> 00:14:20,732 which, by the way, are wrong. 374 00:14:20,732 --> 00:14:22,630 - (laughs) Yeah. 375 00:14:22,630 --> 00:14:24,550 - Are mistaken, we know that, but nevertheless, 376 00:14:24,550 --> 00:14:27,240 he convinced the world that, not by giving good argument, 377 00:14:27,240 --> 00:14:29,680 in fact, he is wrong, but by showing 378 00:14:29,680 --> 00:14:33,990 that there's nothing wrong in accepting that something 379 00:14:33,990 --> 00:14:36,500 completely obvious to you, it's not right. 380 00:14:36,500 --> 00:14:38,110 But that was not your question. 381 00:14:38,110 --> 00:14:41,620 Your question, well, what's a strategy we can go to 382 00:14:42,690 --> 00:14:46,190 for not being trapped in our own beliefs, 383 00:14:46,190 --> 00:14:47,680 and I don't know. 384 00:14:47,680 --> 00:14:49,352 Scientists are like everybody else. 385 00:14:49,352 --> 00:14:50,770 - Right. - Is it more 386 00:14:50,770 --> 00:14:53,524 than being aware of that, keep repeating it to ourself? 387 00:14:53,524 --> 00:14:55,177 (chuckles) That, I don't know what's the right way 388 00:14:55,177 --> 00:14:57,200 of doing so. - Yeah. 389 00:14:57,200 --> 00:14:59,650 - Do you remember a moment in your earlier life 390 00:14:59,650 --> 00:15:01,860 when maybe physics, or science itself, 391 00:15:01,860 --> 00:15:04,450 sort of revealed to you this new way of looking 392 00:15:04,450 --> 00:15:06,730 or unlearning things you may have known 393 00:15:06,730 --> 00:15:08,470 and opened your eyes to new possibilities? 394 00:15:08,470 --> 00:15:10,290 Was there an epiphany there, 395 00:15:10,290 --> 00:15:12,967 or was it a series of happenings? 396 00:15:12,967 --> 00:15:14,750 - It was a series of happenings, 397 00:15:14,750 --> 00:15:18,320 starting from when I was a student. 398 00:15:18,320 --> 00:15:20,660 I fell in love with science late, 399 00:15:20,660 --> 00:15:24,090 when I was already a university student in physics. 400 00:15:24,090 --> 00:15:28,100 In studying modern physics, it was a series of shocks, 401 00:15:28,100 --> 00:15:31,160 like, oh, my God, somehow reality is not what it seems. 402 00:15:31,160 --> 00:15:32,730 That became the title of my book. 403 00:15:32,730 --> 00:15:35,250 So, it was a strong experience at that time. 404 00:15:35,250 --> 00:15:37,800 - Is that a phrase that you've had in your mind 405 00:15:37,800 --> 00:15:39,360 for a long time before the book came out, 406 00:15:39,360 --> 00:15:40,910 that reality is not what it seems? 407 00:15:40,910 --> 00:15:44,400 Is that sort of the realization you had those years ago? 408 00:15:44,400 --> 00:15:46,470 - The concept, yes. - Yeah. 409 00:15:46,470 --> 00:15:50,440 - For sure, somehow it grew with me in various manners. 410 00:15:50,440 --> 00:15:51,700 The phrase itself, I'm not sure. 411 00:15:51,700 --> 00:15:53,540 I think it came from the text of the book, 412 00:15:53,540 --> 00:15:56,460 and then I picked it up because it represented 413 00:15:56,460 --> 00:15:58,170 what was going on. 414 00:15:58,170 --> 00:15:59,850 - You mentioned quantum gravity before, 415 00:15:59,850 --> 00:16:01,377 and there's a line in your book, 416 00:16:01,377 --> 00:16:03,020 "Seven Brief Lessons on Physics". 417 00:16:03,020 --> 00:16:05,117 It's just such a simple short line, 418 00:16:05,117 --> 00:16:08,020 "There is a paradox at the heart of our understanding 419 00:16:08,020 --> 00:16:09,360 of the physical world." 420 00:16:09,360 --> 00:16:11,080 That paradox is essentially, I think, 421 00:16:11,080 --> 00:16:12,640 the root of quantum gravity, 422 00:16:12,640 --> 00:16:15,720 that paradox between general relativity 423 00:16:15,720 --> 00:16:17,080 and quantum mechanics. 424 00:16:17,080 --> 00:16:20,480 Can you elaborate a bit more on why that's a paradox, 425 00:16:20,480 --> 00:16:22,570 what paradox we're struggling with, 426 00:16:22,570 --> 00:16:24,910 and why we need a solution to it? 427 00:16:24,910 --> 00:16:27,600 - I believe it is an apparent paradox, 428 00:16:27,600 --> 00:16:31,570 that it's strikingly paradoxical, the way it looks. 429 00:16:31,570 --> 00:16:35,450 It's what a student of physics learns 430 00:16:35,450 --> 00:16:38,600 when he goes to school at the university 431 00:16:38,600 --> 00:16:41,310 and he just minimally thinks, 432 00:16:41,310 --> 00:16:44,470 because you go to classes on quantum mechanics 433 00:16:44,470 --> 00:16:46,660 and you get your explanation of the world, 434 00:16:46,660 --> 00:16:49,020 and the world is all about discreteness. 435 00:16:49,020 --> 00:16:52,280 Light is photons, and it's just discrete particles. 436 00:16:52,280 --> 00:16:54,470 They're minute particle bits of things. 437 00:16:54,470 --> 00:16:56,600 Everything is in bits and chunks. 438 00:16:56,600 --> 00:16:57,910 It's probabilistic. 439 00:16:57,910 --> 00:17:00,130 There is this strange, 440 00:17:00,130 --> 00:17:03,420 interactive thing from which, in quantum mechanics, 441 00:17:03,420 --> 00:17:05,870 you predict how things interact with one another. 442 00:17:05,870 --> 00:17:08,370 So, you say, okay, that's the way reality is. 443 00:17:08,370 --> 00:17:11,130 I mean, okay, God did reality like that, I mean, 444 00:17:11,130 --> 00:17:13,540 we don't know what she thinks or why, 445 00:17:13,540 --> 00:17:14,570 but that's the way reality is. 446 00:17:14,570 --> 00:17:16,210 And then you go to the other class, 447 00:17:16,210 --> 00:17:18,000 with this other teacher that teaches you 448 00:17:18,000 --> 00:17:19,920 about general relativity, and this is, you know, 449 00:17:19,920 --> 00:17:23,270 an equally immense, fundamental, successful theory, 450 00:17:23,270 --> 00:17:25,460 and the universe is perfectly continuous. 451 00:17:25,460 --> 00:17:27,220 There's nothing probabilistic, 452 00:17:27,220 --> 00:17:29,260 deterministic equations of motion. 453 00:17:29,260 --> 00:17:32,190 Everything is perfectly objective out there. 454 00:17:32,190 --> 00:17:35,800 You can write the history of spacetime in a single equation. 455 00:17:35,800 --> 00:17:36,910 And then I think, wait a minute. 456 00:17:36,910 --> 00:17:39,130 I mean, either one or the other, there cannot be, I mean, 457 00:17:39,130 --> 00:17:41,584 my teachers stopped talking to one another, 458 00:17:41,584 --> 00:17:44,110 (chuckles) haven't talked to one another for 30 years. 459 00:17:44,110 --> 00:17:46,730 So, it's really two totally different images 460 00:17:46,730 --> 00:17:49,210 of how reality works. 461 00:17:49,210 --> 00:17:51,220 God can be complicated, I don't know, 462 00:17:51,220 --> 00:17:53,230 but not so self-contradictory. 463 00:17:53,230 --> 00:17:55,540 The world is either this way or the other way, 464 00:17:55,540 --> 00:17:57,950 or some way which is compatible with both. 465 00:17:57,950 --> 00:17:59,013 - And is that the question 466 00:17:59,013 --> 00:17:59,920 of quantum gravity? - That's quantum gravity. 467 00:17:59,920 --> 00:18:02,700 Exactly. - Speaking of quantum gravity, 468 00:18:02,700 --> 00:18:03,660 as part of this show, 469 00:18:03,660 --> 00:18:06,080 we collect questions from other listeners, 470 00:18:06,080 --> 00:18:09,860 and a mutual friend of ours, Carlo, Lin-Qing Chen, 471 00:18:09,860 --> 00:18:12,610 she's a postdoctoral researcher in Brussels, Belgium, 472 00:18:12,610 --> 00:18:14,420 she sent in a question for you. 473 00:18:14,420 --> 00:18:15,360 - Oh, fantastic. 474 00:18:15,360 --> 00:18:17,380 - Hi, Carlo, this is Lin-Qing. 475 00:18:17,380 --> 00:18:21,550 So, in our quest for a theory of quantum gravity, 476 00:18:21,550 --> 00:18:25,880 do you think we will need new fundamental principles 477 00:18:25,880 --> 00:18:29,660 that both quantum mechanics or general relativity 478 00:18:29,660 --> 00:18:32,400 have not yet revealed to us, 479 00:18:32,400 --> 00:18:36,010 and what is your strategy for finding them out? 480 00:18:36,010 --> 00:18:37,410 Thank you. 481 00:18:37,410 --> 00:18:40,020 - The answer I have, I'm not sure, 482 00:18:40,020 --> 00:18:43,140 but that answer on which I'm working is no. 483 00:18:43,140 --> 00:18:44,070 No to the question, do you think 484 00:18:44,070 --> 00:18:48,320 there is some fundamental principle that we'll be missing? 485 00:18:48,320 --> 00:18:50,040 I think that the idea that, oh, 486 00:18:50,040 --> 00:18:51,890 we are missing something crucial, 487 00:18:51,890 --> 00:18:54,630 fundamental down there is just wrong. 488 00:18:54,630 --> 00:18:57,610 The point is that we have to take seriously what we learn 489 00:18:57,610 --> 00:19:00,500 with quantum mechanics and seriously what we learn 490 00:19:00,500 --> 00:19:03,280 about general relativity, and bring them together, 491 00:19:03,280 --> 00:19:04,950 and they do go together. 492 00:19:04,950 --> 00:19:07,750 I'm a very conservative guy from this perspective. 493 00:19:07,750 --> 00:19:10,320 I don't believe we need something new, 494 00:19:10,320 --> 00:19:13,730 a supersymmetry with other worlds, many dimensions, 495 00:19:13,730 --> 00:19:15,360 breaking the Lorentz invariance, 496 00:19:15,360 --> 00:19:17,780 of correction to quantum mechanics. 497 00:19:17,780 --> 00:19:21,290 Nature has been saying no to all the attempts 498 00:19:21,290 --> 00:19:24,050 to test this alternative hypothesis so far, 499 00:19:24,050 --> 00:19:27,330 so I don't see any evidence that we're missing something. 500 00:19:27,330 --> 00:19:29,840 General relativity, it's about spacetime, 501 00:19:29,840 --> 00:19:31,485 so it's a shape of spacetime, 502 00:19:31,485 --> 00:19:33,310 a shape of space and a shape of time, 503 00:19:33,310 --> 00:19:34,970 which means how different clocks move with respect 504 00:19:34,970 --> 00:19:38,700 to one another and how meters measure jobs, 505 00:19:38,700 --> 00:19:41,810 and that's quantum, and so we have to understand 506 00:19:41,810 --> 00:19:43,717 the quantum properties of time 507 00:19:43,717 --> 00:19:46,080 and the quantum property of space. 508 00:19:46,080 --> 00:19:47,130 That's radical. 509 00:19:47,130 --> 00:19:49,980 So, the assumption is conservative, but if you follow up, 510 00:19:49,980 --> 00:19:51,910 this is completely radical because it means 511 00:19:51,910 --> 00:19:54,460 this continuous space that you thought it was, 512 00:19:54,460 --> 00:19:55,760 forget about it. 513 00:19:55,760 --> 00:19:58,890 The time evolution in a single variable, forget about it. 514 00:19:58,890 --> 00:20:01,700 You have to replace the usual way of thinking space, 515 00:20:01,700 --> 00:20:03,480 the usual way of thinking time 516 00:20:03,480 --> 00:20:05,850 with something consistent with quantum mechanics, 517 00:20:05,850 --> 00:20:08,140 but not this quantum mechanics in spacetime, 518 00:20:08,140 --> 00:20:09,600 quantum mechanics off spacetime. 519 00:20:09,600 --> 00:20:12,340 So, for instance, you have to have mathematics 520 00:20:12,340 --> 00:20:14,900 and a physical intuition that allows you 521 00:20:14,900 --> 00:20:18,670 for having quantum superposition of spacetimes, 522 00:20:18,670 --> 00:20:20,010 plural, of geometries. 523 00:20:20,010 --> 00:20:22,990 Like, there is shooting a cat that can be both awake 524 00:20:22,990 --> 00:20:25,180 and asleep, or somebody said dead and alive. 525 00:20:25,180 --> 00:20:26,600 - I like your version better. - (laughs) Yeah. 526 00:20:26,600 --> 00:20:28,347 - I like cats, so. - Yeah, exactly. 527 00:20:28,347 --> 00:20:30,750 So, shooting a cat in quantum mechanics 528 00:20:30,750 --> 00:20:33,290 is it can be both awake and sleeping. 529 00:20:33,290 --> 00:20:35,100 And so, in the same sense, 530 00:20:35,100 --> 00:20:37,140 space can have a shape and also another shape 531 00:20:37,140 --> 00:20:38,173 in a superposition of the two, 532 00:20:38,173 --> 00:20:41,450 and, of course, this requires imagination, 533 00:20:41,450 --> 00:20:43,940 finding the right concept to talk about that. 534 00:20:43,940 --> 00:20:46,200 That's also where philosophy comes in useful, 535 00:20:46,200 --> 00:20:47,920 and the right mathematics, 536 00:20:47,920 --> 00:20:49,410 and I think there are, I mean, 537 00:20:49,410 --> 00:20:51,430 loop quantum gravity is an example of a theory 538 00:20:51,430 --> 00:20:52,680 that attempts to do that. 539 00:20:52,680 --> 00:20:54,100 We don't know if it is right. 540 00:20:54,100 --> 00:20:55,670 It's very conservative, 541 00:20:55,670 --> 00:20:58,530 and that's why the answer to Lin-Qing's question is no. 542 00:20:58,530 --> 00:21:01,592 So, there's no other principle to be added, 543 00:21:01,592 --> 00:21:04,190 but it's completely radical then because it forces us 544 00:21:04,190 --> 00:21:06,710 to rethink the basic notions. 545 00:21:06,710 --> 00:21:08,970 - And you mentioned evidence when you were giving 546 00:21:08,970 --> 00:21:11,020 this explanation, looking for evidence 547 00:21:11,020 --> 00:21:13,560 to support various theories of quantum gravity. 548 00:21:13,560 --> 00:21:16,480 What kind of evidence would you be looking for? 549 00:21:16,480 --> 00:21:18,800 - Recently, there has been a lot of evidence 550 00:21:18,800 --> 00:21:21,730 that helps us, and in science, 551 00:21:21,730 --> 00:21:26,130 evidence is never definitive, it's always indications, 552 00:21:26,130 --> 00:21:29,050 like in life, by the way. (laughs) 553 00:21:29,050 --> 00:21:30,410 It's not that you kill a theory. 554 00:21:30,410 --> 00:21:33,220 It's very rarely that you really, really kill a theory 555 00:21:33,220 --> 00:21:36,200 with an experiment, but you create problems to a theory, 556 00:21:36,200 --> 00:21:37,810 and when a theory has too many problems, 557 00:21:37,810 --> 00:21:39,010 you look somewhere else, 558 00:21:39,010 --> 00:21:40,830 and there have been a lot of these things recently. 559 00:21:40,830 --> 00:21:44,010 The strongest and the most unexpected for many people 560 00:21:44,010 --> 00:21:46,200 has been the absence of low-energy supersymmetry. 561 00:21:46,200 --> 00:21:48,470 There was a big part of the community 562 00:21:48,470 --> 00:21:52,540 that was completely convinced, sort of 99.9%, 563 00:21:52,540 --> 00:21:55,430 that supersymmetry was going to be detected- 564 00:21:55,430 --> 00:21:56,390 - By the Large Hadron Collider? 565 00:21:56,390 --> 00:21:57,686 - At CERN, right. - Yeah. 566 00:21:57,686 --> 00:21:58,769 - It was LHC, 567 00:21:59,780 --> 00:22:01,330 and it wasn't. 568 00:22:01,330 --> 00:22:03,460 It was a shock, there were titles of the journals, 569 00:22:03,460 --> 00:22:05,290 like, you know, this is a crisis of physics. 570 00:22:05,290 --> 00:22:07,090 Of course, it's not the crisis of physics. 571 00:22:07,090 --> 00:22:09,080 It's only the crisis for those who expected it, 572 00:22:09,080 --> 00:22:09,913 which is not physics, 573 00:22:09,913 --> 00:22:11,610 it's just a particular school of thought. 574 00:22:11,610 --> 00:22:13,060 But that's nature talking, 575 00:22:13,060 --> 00:22:14,530 and when nature is talking, we should listen. 576 00:22:14,530 --> 00:22:17,430 Another example is breaking the Lorentz invariance, 577 00:22:17,430 --> 00:22:20,270 the symmetry at the basis of Einstein special relativity, 578 00:22:20,270 --> 00:22:21,750 which is Lorentz invariance. 579 00:22:21,750 --> 00:22:23,960 Some people thought, also, that was like supersymmetry. 580 00:22:23,960 --> 00:22:25,850 It was a very nice idea. 581 00:22:25,850 --> 00:22:29,140 You can make the point of quantum gravity easier 582 00:22:29,140 --> 00:22:30,660 if you don't have Lorentz invariance. 583 00:22:30,660 --> 00:22:32,470 So, people try to provide theories 584 00:22:32,470 --> 00:22:33,780 which break Lorentz invariance 585 00:22:33,780 --> 00:22:36,580 and might be quantum gravity theories. 586 00:22:36,580 --> 00:22:37,870 So, this was tested, 587 00:22:37,870 --> 00:22:40,460 15 years now of astrophysical observations, 588 00:22:40,460 --> 00:22:42,530 and all the expected signs 589 00:22:42,530 --> 00:22:44,610 of breaking Lorentz invariance, zero. 590 00:22:44,610 --> 00:22:46,480 Once again, nature talks. 591 00:22:46,480 --> 00:22:48,850 As far as we know, nature is saying, "No, no, no, no, guys, 592 00:22:48,850 --> 00:22:50,610 that's not the right way to look for the solution." 593 00:22:50,610 --> 00:22:52,370 So, I think nature is giving indication, I mean, 594 00:22:52,370 --> 00:22:55,330 a lot of people expect a negative cosmological constant. 595 00:22:55,330 --> 00:22:57,400 Even today, there is a large part of the community 596 00:22:57,400 --> 00:22:59,670 that continues to do calculations and calculations 597 00:22:59,670 --> 00:23:02,446 and calculations with a negative cosmological constant, 598 00:23:02,446 --> 00:23:03,940 or AdS/CFT. 599 00:23:03,940 --> 00:23:07,010 AdS means anti-de Sitter, which means there's a space 600 00:23:07,010 --> 00:23:09,520 with an effective negative cosmological constant, 601 00:23:09,520 --> 00:23:11,410 and you accept that the cosmological constant 602 00:23:11,410 --> 00:23:13,990 has been measured by the astronomers, by the cosmologists. 603 00:23:13,990 --> 00:23:15,840 In a very convincing way, they got the Nobel Prize, 604 00:23:15,840 --> 00:23:18,400 the ones who did that, and it's positive. 605 00:23:18,400 --> 00:23:21,670 So, once again, I think my interpretation, 606 00:23:21,670 --> 00:23:24,327 my reading of that as a scientist, I mean, I might be wrong, 607 00:23:24,327 --> 00:23:27,910 but my reading of that is that nature is talking, listen. 608 00:23:27,910 --> 00:23:28,940 That's not the right direction. 609 00:23:28,940 --> 00:23:30,910 - How will nature speak to you to advance 610 00:23:30,910 --> 00:23:32,710 loop quantum gravity, say. 611 00:23:32,710 --> 00:23:34,360 - There are two or three directions 612 00:23:34,360 --> 00:23:37,720 where me and many of my colleagues are looking into. 613 00:23:37,720 --> 00:23:39,160 For the moment, zero, 614 00:23:39,160 --> 00:23:42,820 so we have no negative response from nature, 615 00:23:42,820 --> 00:23:44,469 but we don't have any positive response 616 00:23:44,469 --> 00:23:46,300 (laughing) from nature. - Can you explain that a bit? 617 00:23:46,300 --> 00:23:49,170 - We don't know, so there's nothing that has come 618 00:23:49,170 --> 00:23:52,010 as a contradiction to what we expected, 619 00:23:52,010 --> 00:23:53,670 but there's nothing that has come 620 00:23:53,670 --> 00:23:55,950 to confirm predictions of the theory either, 621 00:23:55,950 --> 00:23:57,197 so I cannot say that quantum gravity 622 00:23:57,197 --> 00:23:59,010 is confirmed in any sense. 623 00:23:59,010 --> 00:24:01,510 So, where could the confirmation come from? 624 00:24:01,510 --> 00:24:02,910 I see three possible directions. 625 00:24:02,910 --> 00:24:04,550 One is the early cosmology. 626 00:24:04,550 --> 00:24:07,470 There's a lot of literature, papers, and papers written. 627 00:24:07,470 --> 00:24:10,580 So, the universe, we know, came out in the Big Bang, 628 00:24:10,580 --> 00:24:14,040 the very early moment, at the beginning of its life, 629 00:24:14,040 --> 00:24:16,260 deep into quantum gravity regime, 630 00:24:16,260 --> 00:24:18,930 so that's where quantum gravity should appear. 631 00:24:18,930 --> 00:24:21,890 A lot of colleagues have applied loop quantum gravity 632 00:24:21,890 --> 00:24:23,830 to describe what happens there. 633 00:24:23,830 --> 00:24:26,580 It seems to be working, and to see if one 634 00:24:26,580 --> 00:24:29,180 can predict effects of what happened there 635 00:24:29,180 --> 00:24:32,000 that can be tested in the cosmic background radiation, 636 00:24:32,000 --> 00:24:35,330 it's possible, measurements getting more precise. 637 00:24:35,330 --> 00:24:37,150 I hope they will convert it with something useful, 638 00:24:37,150 --> 00:24:38,230 but for the moment, there's nothing. 639 00:24:38,230 --> 00:24:40,320 That's one, the second one is black holes. 640 00:24:40,320 --> 00:24:41,700 I'm working on black holes. 641 00:24:41,700 --> 00:24:44,080 Loop quantum gravity is consistent very much with the idea 642 00:24:44,080 --> 00:24:46,260 that a black hole evaporates. 643 00:24:46,260 --> 00:24:48,780 That's Hawking's realization, that black holes evaporate. 644 00:24:48,780 --> 00:24:51,490 They become smaller, smaller, smaller, and then, at the end, 645 00:24:51,490 --> 00:24:54,080 they don't just disappear, pop out of existence, 646 00:24:54,080 --> 00:24:56,350 but there's a remnant, which is a white hole. 647 00:24:56,350 --> 00:24:59,400 So, there's a quantum gravity transition jump 648 00:24:59,400 --> 00:25:01,740 from a black hole to a white hole, with a little throat, 649 00:25:01,740 --> 00:25:03,900 but a huge inside. 650 00:25:03,900 --> 00:25:06,467 And then this white hole, slowly, things come out, 651 00:25:06,467 --> 00:25:08,740 where the information slowly comes out, 652 00:25:08,740 --> 00:25:10,250 lives for a very long time. 653 00:25:10,250 --> 00:25:11,480 So, this is a scenario, 654 00:25:11,480 --> 00:25:14,190 it might have astrophysical consequences. 655 00:25:14,190 --> 00:25:16,370 These have been explored by this group, 656 00:25:16,370 --> 00:25:18,593 including London and the people I'm working with. 657 00:25:18,593 --> 00:25:20,750 There's one of these possibilities, 658 00:25:20,750 --> 00:25:22,710 which I'm particularly attracted to, 659 00:25:22,710 --> 00:25:25,340 which is that these little things that float around 660 00:25:25,340 --> 00:25:28,700 in the universe are actually dark matter, 661 00:25:28,700 --> 00:25:30,460 or a component of dark matter. 662 00:25:30,460 --> 00:25:32,780 If so, it might be that we have already observed something, 663 00:25:32,780 --> 00:25:34,210 we just haven't recognized it. 664 00:25:34,210 --> 00:25:36,450 - Dark matter being another great puzzle 665 00:25:36,450 --> 00:25:38,030 of modern physics. - Dark matter, 666 00:25:38,030 --> 00:25:40,320 it's a big puzzle, and that's the opposite 667 00:25:40,320 --> 00:25:42,300 of the quantum gravity puzzle, because it's not a puzzle 668 00:25:42,300 --> 00:25:45,230 in our understanding, it's a puzzle in what we see. 669 00:25:45,230 --> 00:25:47,270 You look at the universe around us 670 00:25:47,270 --> 00:25:50,260 and we see galaxies, starts, clouds of hydrogen, 671 00:25:50,260 --> 00:25:53,540 all sorts of stuff, and then there is this stuff out there, 672 00:25:53,540 --> 00:25:55,490 something that produces effect out there. 673 00:25:55,490 --> 00:25:58,090 We see the gravitational effect of these things. 674 00:25:58,090 --> 00:25:59,790 We have quite convincing evidence 675 00:25:59,790 --> 00:26:01,013 that it's not usual matter. 676 00:26:01,013 --> 00:26:03,780 It's not just atoms or molecules or protons 677 00:26:03,780 --> 00:26:06,190 or neutrinos or photons, 678 00:26:06,190 --> 00:26:08,133 it's something else, and it's a lot. 679 00:26:08,133 --> 00:26:10,880 There's quite as much normal matter and dark matter, 680 00:26:10,880 --> 00:26:13,880 even more dark matter, and nobody knows what it is, 681 00:26:13,880 --> 00:26:15,240 so it's fantastic. 682 00:26:15,240 --> 00:26:17,740 People who say that we're close to the end of physics 683 00:26:17,740 --> 00:26:19,920 and close to the theory of everything, come on, guys, 684 00:26:19,920 --> 00:26:21,750 we don't even know what we see around us. 685 00:26:21,750 --> 00:26:23,740 So, dark matter is really an important question. 686 00:26:23,740 --> 00:26:25,940 We have a lot of possible explanations, 687 00:26:25,940 --> 00:26:29,530 but many are non, confirmed non, really, credible. 688 00:26:29,530 --> 00:26:31,180 I like the black hole ones 689 00:26:31,180 --> 00:26:35,270 because it does not rely on any new assumption. 690 00:26:35,270 --> 00:26:36,503 Well, if there's black holes, 691 00:26:36,503 --> 00:26:38,260 it's just nothing we know exists. 692 00:26:38,260 --> 00:26:40,190 - It's funny, you said it's a mystery, 693 00:26:40,190 --> 00:26:42,240 we don't know, and that's fantastic. 694 00:26:42,240 --> 00:26:44,320 That's not always the case in a lot of professions, 695 00:26:44,320 --> 00:26:46,027 where the lack of knowledge about something 696 00:26:46,027 --> 00:26:47,890 is something you're excited about. 697 00:26:47,890 --> 00:26:51,180 Are you glad that physics is nowhere near being complete? 698 00:26:51,180 --> 00:26:52,677 - Oh, infinitely so, of course, 699 00:26:52,677 --> 00:26:54,980 otherwise it would be boring, right? 700 00:26:54,980 --> 00:26:58,180 Imagine what a disaster if somebody wrote, "Okay, I got it, 701 00:26:58,180 --> 00:27:00,380 everything, this is the final equation of everything." 702 00:27:00,380 --> 00:27:01,277 - But that's what you're going for. 703 00:27:01,277 --> 00:27:02,110 - No. - No? 704 00:27:02,110 --> 00:27:04,040 - No, zero. - Is quantum gravity 705 00:27:04,040 --> 00:27:07,690 not sort of that grand, unifying theory? 706 00:27:07,690 --> 00:27:09,113 - No, it's a step on the way. 707 00:27:09,113 --> 00:27:11,280 It's just figuring out what is the quantum property 708 00:27:11,280 --> 00:27:12,460 of space and time. 709 00:27:12,460 --> 00:27:14,800 I'm not working for material of everything, 710 00:27:14,800 --> 00:27:16,250 I'm working just for a next step 711 00:27:16,250 --> 00:27:17,440 in understanding what's around. 712 00:27:17,440 --> 00:27:20,600 - Once we've figured out the quantum nature of spacetime, 713 00:27:20,600 --> 00:27:23,760 does that open up new questions or help us answer old ones? 714 00:27:23,760 --> 00:27:27,540 - I suppose loop quantum gravity is confirmed. 715 00:27:27,540 --> 00:27:29,490 With a colleague, Marios Christodoulou, 716 00:27:29,490 --> 00:27:31,800 we have an experiment which we proposed, 717 00:27:31,800 --> 00:27:34,960 which might even be doable in 10 years or so, 718 00:27:34,960 --> 00:27:37,580 which would actually test the discreteness of time 719 00:27:37,580 --> 00:27:38,767 predicted by loop quantum gravity. 720 00:27:38,767 --> 00:27:40,990 So, suppose this can be done, and bingo, 721 00:27:40,990 --> 00:27:43,530 the right numbers, because loop quantum gravity 722 00:27:43,530 --> 00:27:45,400 predicts that space is discrete, right? 723 00:27:45,400 --> 00:27:48,260 It's granular, like light is made by photons, 724 00:27:48,260 --> 00:27:51,320 spaces make this grain of space, but also time, 725 00:27:51,320 --> 00:27:53,350 I expect it has this granularity. 726 00:27:53,350 --> 00:27:55,160 We have an idea of, perhaps, 727 00:27:55,160 --> 00:27:57,290 with some slight advances in technology, 728 00:27:57,290 --> 00:27:59,422 not excessive, it could be tested. 729 00:27:59,422 --> 00:28:01,510 Now, suppose this comes out right. 730 00:28:01,510 --> 00:28:03,320 Loop quantum gravity is correct, perfect, 731 00:28:03,320 --> 00:28:05,627 the right numbers are there, now what? 732 00:28:05,627 --> 00:28:08,360 Well, now we still have a universe 733 00:28:08,360 --> 00:28:11,070 described by a funny standard model, 734 00:28:11,070 --> 00:28:14,110 where the weak interactions and the strong interactions 735 00:28:14,110 --> 00:28:17,330 are completely separated, described by similar theories, 736 00:28:17,330 --> 00:28:19,570 but not really unified in any way. 737 00:28:19,570 --> 00:28:22,470 Gravity described by still another theory. 738 00:28:22,470 --> 00:28:24,560 19 parameters for the standard model. 739 00:28:24,560 --> 00:28:26,420 Who chose them? Why? 740 00:28:26,420 --> 00:28:28,340 Three generations. 741 00:28:28,340 --> 00:28:31,400 Suppose with quantum gravity, we figure out the Big Bang, 742 00:28:31,400 --> 00:28:32,863 and what seems likely is that it was not, 743 00:28:32,863 --> 00:28:34,940 that the initial exposure was a bounce. 744 00:28:34,940 --> 00:28:36,900 It's an idea studied by various people. 745 00:28:36,900 --> 00:28:38,160 - That our universe is the result 746 00:28:38,160 --> 00:28:40,580 of a previous one collapsing and expanding again? 747 00:28:40,580 --> 00:28:42,970 - Some universe was collapsing, in some sense, 748 00:28:42,970 --> 00:28:44,140 under its own weight. 749 00:28:44,140 --> 00:28:46,350 It gets to the sort of maximum compression, 750 00:28:46,350 --> 00:28:47,660 where quantum gravity comes in. 751 00:28:47,660 --> 00:28:49,410 It bounces, and then what we see 752 00:28:49,410 --> 00:28:51,510 as the Big Bang is this bounce. 753 00:28:51,510 --> 00:28:53,450 I think it's a reasonable hypothesis. 754 00:28:53,450 --> 00:28:56,550 It seems to be more reasonable than the Big Bang. 755 00:28:56,550 --> 00:28:58,490 Suppose we figured this out. 756 00:28:58,490 --> 00:28:59,720 Have we solved everything? 757 00:28:59,720 --> 00:29:00,810 No, of course, I mean, 758 00:29:00,810 --> 00:29:04,182 where was the collapsing universe coming from? 759 00:29:04,182 --> 00:29:06,210 (chuckles) I mean, what was there? 760 00:29:06,210 --> 00:29:10,640 It seems, today, so impossibly difficult to figure out 761 00:29:10,640 --> 00:29:12,510 what was in the collapsing universe, 762 00:29:12,510 --> 00:29:14,440 but at the time of my great-grandfather, 763 00:29:14,440 --> 00:29:16,820 it seemed impossible to discover 764 00:29:16,820 --> 00:29:19,230 what was the chemical composition of Jupiter. 765 00:29:19,230 --> 00:29:21,780 I mean, it was considered an unsolvable problem. 766 00:29:21,780 --> 00:29:23,910 I mean, now we know, in Jupiter, everything, 767 00:29:23,910 --> 00:29:25,990 even, you know, if there were ants there, 768 00:29:25,990 --> 00:29:26,823 we would've seen that. 769 00:29:26,823 --> 00:29:31,720 So, science finds new problems and grows at all levels 770 00:29:31,720 --> 00:29:34,600 if the mystery is not a reason of sadness, 771 00:29:34,600 --> 00:29:37,923 it's a reason of joy because a new thing's discovered. 772 00:29:37,923 --> 00:29:39,890 It's the beauty of understanding. 773 00:29:39,890 --> 00:29:41,360 - You're still, like Isaac Newton, 774 00:29:41,360 --> 00:29:44,115 playing with pebbles on the vast sea of what we don't know? 775 00:29:44,115 --> 00:29:46,550 - Absolutely. - And regarding this, 776 00:29:46,550 --> 00:29:49,430 you know, general idea of working in a field, 777 00:29:49,430 --> 00:29:52,510 where you maybe don't yet have evidence for or against it, 778 00:29:52,510 --> 00:29:54,870 it just reminds me of something you write about 779 00:29:54,870 --> 00:29:56,610 in your book, "Seven Brief Lessons". 780 00:29:56,610 --> 00:29:58,450 When you're talking about Einstein's theory, 781 00:29:58,450 --> 00:30:00,810 you write about how, a lot of times, 782 00:30:00,810 --> 00:30:04,310 something very important is kind of considered useless 783 00:30:04,310 --> 00:30:05,670 at the time when it's developed. 784 00:30:05,670 --> 00:30:08,310 One example you gave is that Rehman's work, 785 00:30:08,310 --> 00:30:11,270 that was generalizing Gauss's explanations, 786 00:30:11,270 --> 00:30:12,880 was considered useless at the time, 787 00:30:12,880 --> 00:30:16,600 but it was then a fundamental piece of Einstein's theory. 788 00:30:16,600 --> 00:30:18,330 So, it seems that this is very crucial, 789 00:30:18,330 --> 00:30:20,760 to work on things where we don't actually know 790 00:30:20,760 --> 00:30:22,610 exactly what the application will be 791 00:30:22,610 --> 00:30:25,830 or exactly how long it will be, but I'm wondering 792 00:30:25,830 --> 00:30:27,960 if you think that physicists need to find, in general, 793 00:30:27,960 --> 00:30:30,710 some kind of a balance between working on problems 794 00:30:30,710 --> 00:30:33,300 where we have an idea of the time horizon 795 00:30:33,300 --> 00:30:36,500 for the applications versus working on these problems 796 00:30:36,500 --> 00:30:39,660 where we don't really know where it will lead. 797 00:30:39,660 --> 00:30:43,690 - Yes, obviously there is a balance to be searched there. 798 00:30:43,690 --> 00:30:47,140 If you look at this from the main whole of Perimeter, 799 00:30:47,140 --> 00:30:49,280 as this is the same city, hard to find balance, 800 00:30:49,280 --> 00:30:51,090 but if you look at it on a large scale, 801 00:30:51,090 --> 00:30:55,070 99.9% of the money put into research worldwide 802 00:30:55,070 --> 00:30:57,040 is to practical applications. 803 00:30:57,040 --> 00:30:58,880 Of course, we need practical applications, right? 804 00:30:58,880 --> 00:31:01,810 We need people who study chemistry of materials 805 00:31:01,810 --> 00:31:04,070 because we need the certain materials for something, 806 00:31:04,070 --> 00:31:05,970 healing people and replacing bones. 807 00:31:05,970 --> 00:31:07,220 I'm just defending. 808 00:31:07,220 --> 00:31:08,750 Applied science is great, 809 00:31:08,750 --> 00:31:12,880 but to concentrate resources toward applied science so much, 810 00:31:12,880 --> 00:31:15,470 as is done today, I think, it's a disaster. 811 00:31:15,470 --> 00:31:18,860 We need people who do the kind of pure science 812 00:31:18,860 --> 00:31:21,020 or fundamental science or basic science, 813 00:31:21,020 --> 00:31:23,960 I mean, all these words are imprecise, all of them, 814 00:31:23,960 --> 00:31:27,170 namely who don't think about application. 815 00:31:27,170 --> 00:31:29,250 Our science is built 816 00:31:29,250 --> 00:31:30,590 upon a number 817 00:31:30,590 --> 00:31:33,900 of key results obtained through the same tests. 818 00:31:33,900 --> 00:31:35,240 If you look at each one, 819 00:31:35,240 --> 00:31:37,220 no one was looking for application, 820 00:31:37,220 --> 00:31:40,100 and if he had looked for application at his own time, 821 00:31:40,100 --> 00:31:41,480 he wouldn't have got there. 822 00:31:41,480 --> 00:31:44,610 So, it's obvious that we need to just ask the question, 823 00:31:44,610 --> 00:31:45,850 what's behind things? 824 00:31:45,850 --> 00:31:48,800 How can I understand better at the fundamental level? 825 00:31:48,800 --> 00:31:51,150 Applications will come out, sometimes fortunately, 826 00:31:51,150 --> 00:31:52,680 sometimes unfortunately 827 00:31:52,680 --> 00:31:55,810 because sometimes applications are to kill people 828 00:31:55,810 --> 00:31:58,220 and to make war. 829 00:31:58,220 --> 00:32:00,720 - So, you're the organizer of a research initiative 830 00:32:00,720 --> 00:32:03,790 called The Quantum Information Structure of Spacetime, 831 00:32:03,790 --> 00:32:05,810 and this brings together theorists, 832 00:32:05,810 --> 00:32:08,240 experimentalists, and philosophers. 833 00:32:08,240 --> 00:32:10,800 Can you tell us why you think it's so useful 834 00:32:10,800 --> 00:32:13,227 to bring together that group of people 835 00:32:13,227 --> 00:32:17,350 and what you're trying to answer through this initiative? 836 00:32:17,350 --> 00:32:18,864 - Thank you for this question. 837 00:32:18,864 --> 00:32:21,040 The Quantum Information Structure of Spacetime, 838 00:32:21,040 --> 00:32:24,810 the short name is QISS, QISS, written with a Q. 839 00:32:24,810 --> 00:32:28,380 It's a big consortium with big grants, 840 00:32:28,380 --> 00:32:31,400 mostly used for supporting young people. 841 00:32:31,400 --> 00:32:32,720 A group of PI here, in fact, 842 00:32:32,720 --> 00:32:34,570 two groups of PIs are part of it, 843 00:32:34,570 --> 00:32:38,000 and there are about dozens of group all over the world, 844 00:32:38,000 --> 00:32:40,610 from Hong Kong to Mexico, to California, 845 00:32:40,610 --> 00:32:44,550 and the aim is to bring together two communities, 846 00:32:44,550 --> 00:32:46,170 or actually three communities. 847 00:32:46,170 --> 00:32:48,047 The two communities are quantum information 848 00:32:48,047 --> 00:32:49,640 and quantum gravity, 849 00:32:49,640 --> 00:32:51,820 and the idea is that quantum gravity people 850 00:32:51,820 --> 00:32:54,590 have been using quantum information notions, 851 00:32:54,590 --> 00:32:56,770 or beginning to use it in various ways, 852 00:32:56,770 --> 00:32:59,950 and quantum information people are starting to think 853 00:32:59,950 --> 00:33:04,260 about how quantum information works in space and time. 854 00:33:04,260 --> 00:33:05,390 Let me say it this way, 855 00:33:05,390 --> 00:33:07,101 and so the same problems are being addressed, 856 00:33:07,101 --> 00:33:08,710 but from a completely different perspective. 857 00:33:08,710 --> 00:33:10,270 And the third community is philosophers 858 00:33:10,270 --> 00:33:13,610 because this dialogue opens fundamental questions, 859 00:33:13,610 --> 00:33:15,770 like what we were saying before, 860 00:33:15,770 --> 00:33:18,350 the direction of time or the nature of what is information, 861 00:33:18,350 --> 00:33:21,530 what we mean by information, and in quantum gravity, 862 00:33:21,530 --> 00:33:23,950 it's a theory which is not written in spacetime. 863 00:33:23,950 --> 00:33:26,470 So, in some sense, spacetime has to be rethought 864 00:33:26,470 --> 00:33:28,040 to come out on the theory in some way, 865 00:33:28,040 --> 00:33:29,310 and these are philosophical questions. 866 00:33:29,310 --> 00:33:30,480 So, these are different communities 867 00:33:30,480 --> 00:33:33,890 which are being brought together, and in June this year, 868 00:33:33,890 --> 00:33:36,650 they will be not far from PI in London, Ontario, 869 00:33:36,650 --> 00:33:38,500 so it's just a short drive from PI, 870 00:33:38,500 --> 00:33:40,630 a conference bringing together this, 871 00:33:40,630 --> 00:33:43,490 and it's a conference that we have organized. 872 00:33:43,490 --> 00:33:45,560 It's not a standard conference with, you know, 873 00:33:45,560 --> 00:33:48,320 speeches and a few questions, and, "Why do you say that?" 874 00:33:48,320 --> 00:33:51,890 Each half-day, we'll have a few 10/15 minutes 875 00:33:51,890 --> 00:33:53,710 very short flash presentations, 876 00:33:53,710 --> 00:33:56,520 and then a couple of hours of open discussion, 877 00:33:56,520 --> 00:33:58,720 everybody with everybody, with a good chair, 878 00:33:58,720 --> 00:34:01,470 who sort of likes balance and follows. 879 00:34:01,470 --> 00:34:03,870 Discussion compares all points of view 880 00:34:03,870 --> 00:34:06,060 because there are these communities, quantum information, 881 00:34:06,060 --> 00:34:09,230 quantum gravity, and philosophers who look at these things, 882 00:34:09,230 --> 00:34:11,830 which have different ways of viewing the same thing. 883 00:34:11,830 --> 00:34:14,890 So, we want to compare and, of course, 884 00:34:14,890 --> 00:34:16,710 learn from these differences. 885 00:34:16,710 --> 00:34:18,880 - Are there frustrations that tend to come up 886 00:34:18,880 --> 00:34:22,220 when people with such different backgrounds and education 887 00:34:22,220 --> 00:34:25,330 are trying to discuss a topic with each other? 888 00:34:25,330 --> 00:34:27,500 - Yeah, there are things you take for granted, 889 00:34:27,500 --> 00:34:29,270 then a person who's a good scientist 890 00:34:29,270 --> 00:34:30,370 comes to you and says, "You're wrong." 891 00:34:30,370 --> 00:34:32,380 You say, "Wait, (chuckles) what do you mean I'm wrong, 892 00:34:32,380 --> 00:34:35,530 you are wrong," and that's frustrating, 893 00:34:35,530 --> 00:34:37,160 but that's great because I think 894 00:34:37,160 --> 00:34:38,627 that's how the process of knowledge works. 895 00:34:38,627 --> 00:34:40,930 You know, we learn from experiments, 896 00:34:40,930 --> 00:34:42,400 but we even more learn 897 00:34:42,400 --> 00:34:44,700 from continuous exchange of perspective, 898 00:34:44,700 --> 00:34:47,480 and the more we listen to other perspectives, 899 00:34:47,480 --> 00:34:49,560 and that's a great opportunity, I think, 900 00:34:49,560 --> 00:34:51,530 because quantum information has boomed 901 00:34:51,530 --> 00:34:55,600 for various reasons in the last decade, probably, 902 00:34:55,600 --> 00:34:57,470 and there are very good ideas there, 903 00:34:57,470 --> 00:34:59,480 which I think are relevant for quantum gravity. 904 00:34:59,480 --> 00:35:01,860 On the other hand, the people of quantum information 905 00:35:01,860 --> 00:35:03,560 are not aware that some of the things 906 00:35:03,560 --> 00:35:06,140 that they are struggling with have already been addressed 907 00:35:06,140 --> 00:35:07,400 by quantum gravity, right? 908 00:35:07,400 --> 00:35:11,270 So, there's really a dialogue to start here, 909 00:35:11,270 --> 00:35:13,240 and the philosopher has an interest in both 910 00:35:13,240 --> 00:35:15,300 and have things to say about both. 911 00:35:15,300 --> 00:35:17,580 So, I hope that this dialogue in three, 912 00:35:17,580 --> 00:35:19,360 based not just in presentation, 913 00:35:19,360 --> 00:35:20,556 but in discussion, will work, 914 00:35:20,556 --> 00:35:21,750 and I look forward to that. 915 00:35:21,750 --> 00:35:23,480 - After two years of lockdown, 916 00:35:23,480 --> 00:35:26,340 of pandemics and people staying at home, 917 00:35:26,340 --> 00:35:27,900 have you felt, distinctly, 918 00:35:27,900 --> 00:35:30,770 the absence of in-person gatherings 919 00:35:30,770 --> 00:35:32,870 with other researchers and scientists, 920 00:35:32,870 --> 00:35:35,490 you know, getting together in the same place? 921 00:35:35,490 --> 00:35:36,500 - A little bit, yes. 922 00:35:36,500 --> 00:35:38,100 For me, this has not been dramatic 923 00:35:38,100 --> 00:35:40,510 because we are all on the internet, we're on Zoom, 924 00:35:40,510 --> 00:35:43,400 but being always on Zoom is also painful. 925 00:35:43,400 --> 00:35:46,590 This morning, finally, it's the first day I'm back 926 00:35:46,590 --> 00:35:48,750 in PI after so long, finally! 927 00:35:48,750 --> 00:35:52,430 I was with a young colleague in front of a blackboard, 928 00:35:52,430 --> 00:35:54,910 writing things, and I said, "No, wait, this is not," 929 00:35:54,910 --> 00:35:57,130 as, oh, what a pleasure. (chuckles) 930 00:35:57,130 --> 00:35:58,820 It was so long that this didn't happen. 931 00:35:58,820 --> 00:36:01,680 - And from reading the website for this QISS initiative, 932 00:36:01,680 --> 00:36:04,190 it seems that a major goal is to deepen 933 00:36:04,190 --> 00:36:06,520 the understanding of information. 934 00:36:06,520 --> 00:36:10,320 Could you just tell us what you think of information 935 00:36:10,320 --> 00:36:12,940 as meaning and why you think that information 936 00:36:12,940 --> 00:36:14,620 is so fundamental? 937 00:36:14,620 --> 00:36:16,713 - Information is a very tricky world 'cause the spectral 938 00:36:16,713 --> 00:36:19,680 of meanings is very wide, extremely wide. 939 00:36:19,680 --> 00:36:22,150 When you talk about information, people often get confused 940 00:36:22,150 --> 00:36:24,630 because in a debate, in a dialogue, 941 00:36:24,630 --> 00:36:25,480 people mean different things, 942 00:36:25,480 --> 00:36:28,950 and it goes from the most complex one, 943 00:36:28,950 --> 00:36:31,693 I mean, do you have information about your father? 944 00:36:32,710 --> 00:36:34,380 Of course, I know a lot about my father, 945 00:36:34,380 --> 00:36:36,820 to the most basic one, 946 00:36:36,820 --> 00:36:38,810 my little card here 947 00:36:38,810 --> 00:36:41,900 contains so many megabytes of information. 948 00:36:41,900 --> 00:36:44,390 Obviously, the two are connected somehow, 949 00:36:44,390 --> 00:36:46,620 but the two are very different, completely different. 950 00:36:46,620 --> 00:36:49,170 About your father is something that has to do with meaning. 951 00:36:49,170 --> 00:36:52,180 In that case, with rather even emotions, (chuckles) 952 00:36:52,180 --> 00:36:54,350 but certainly is interpreted information in some sense, 953 00:36:54,350 --> 00:36:58,510 so it has to do with something that needs to be decoded, 954 00:36:58,510 --> 00:37:00,640 that has to be translated. 955 00:37:00,640 --> 00:37:04,390 In the case of the memory card, just counting something, 956 00:37:04,390 --> 00:37:05,960 it's a number of counting something. 957 00:37:05,960 --> 00:37:07,240 It's like counting the number of atoms, 958 00:37:07,240 --> 00:37:08,770 so counting the number of something. 959 00:37:08,770 --> 00:37:10,810 In this spectrum, what is interesting 960 00:37:10,810 --> 00:37:12,320 is exactly the spectrum, 961 00:37:12,320 --> 00:37:15,150 that it has so many possible meanings, 962 00:37:15,150 --> 00:37:17,550 but what's most interesting is the basic one, 963 00:37:17,550 --> 00:37:18,720 and the basic one, 964 00:37:18,720 --> 00:37:21,210 there's a very simple notion of information 965 00:37:21,210 --> 00:37:24,040 which is purely physical, which is correlation, 966 00:37:24,040 --> 00:37:26,070 when two things know about one another. 967 00:37:26,070 --> 00:37:28,037 If you glue two things, if one points in one direction, 968 00:37:28,037 --> 00:37:30,164 the other also points in that direction. 969 00:37:30,164 --> 00:37:31,640 If you know one, you know the other one. 970 00:37:31,640 --> 00:37:33,180 So, one has information about that, 971 00:37:33,180 --> 00:37:35,070 meaning that there is a correlation between the two. 972 00:37:35,070 --> 00:37:35,993 That's the basic notion of information, 973 00:37:35,993 --> 00:37:38,140 it's purely physical, nothing mental, 974 00:37:38,140 --> 00:37:39,730 no meaning, no significance. 975 00:37:39,730 --> 00:37:41,030 That's the basic notion of information, 976 00:37:41,030 --> 00:37:43,560 and I think this notion of information is fundamental, 977 00:37:43,560 --> 00:37:45,347 not because the world is made by information, 978 00:37:45,347 --> 00:37:47,070 the world is made by stuff, 979 00:37:47,070 --> 00:37:48,890 by variables, by things which are, 980 00:37:48,890 --> 00:37:52,710 but because the world is made by relations, 981 00:37:52,710 --> 00:37:55,500 the properties of things are relative to something else. 982 00:37:55,500 --> 00:37:57,067 So, if you want to describe the structure of the world, 983 00:37:57,067 --> 00:37:59,360 you're always talking about how one thing 984 00:37:59,360 --> 00:38:00,330 affects another one, 985 00:38:00,330 --> 00:38:02,290 so how they get correlated to the other one. 986 00:38:02,290 --> 00:38:05,120 So, immediately, you can quantify 987 00:38:05,120 --> 00:38:07,180 how much things affect one another 988 00:38:07,180 --> 00:38:09,780 by using the notion of information, and this means, 989 00:38:09,780 --> 00:38:11,840 not information as an ingredient of the world, 990 00:38:11,840 --> 00:38:14,600 but as a key ingredient of our thinking about the world. 991 00:38:14,600 --> 00:38:16,240 I think quantum mechanics itself 992 00:38:16,240 --> 00:38:18,380 can be largely thought of in this way. 993 00:38:18,380 --> 00:38:20,470 I've been thinking this since back in the '90s, 994 00:38:20,470 --> 00:38:21,930 when I started thinking about the notion 995 00:38:21,930 --> 00:38:24,040 of quantum mechanics, and because of that, 996 00:38:24,040 --> 00:38:25,400 I think, in quantum gravity, 997 00:38:25,400 --> 00:38:27,740 it also could be a fundamental role to thinking 998 00:38:27,740 --> 00:38:30,110 about information systems helping out one another, 999 00:38:30,110 --> 00:38:33,820 but once we go into this way of thinking about physics, 1000 00:38:33,820 --> 00:38:35,550 not as how systems are, 1001 00:38:35,550 --> 00:38:37,700 but how systems have information about all of that, 1002 00:38:37,700 --> 00:38:39,490 how they're correlated, then it's easier 1003 00:38:39,490 --> 00:38:41,640 to understand that there's a continuity 1004 00:38:41,640 --> 00:38:43,980 to the most complicated notion of information. 1005 00:38:43,980 --> 00:38:48,500 So, the mental is not so far away from the physical now 1006 00:38:48,500 --> 00:38:50,440 'cause we start taking the physical 1007 00:38:50,440 --> 00:38:51,770 from the right perspective, 1008 00:38:51,770 --> 00:38:53,670 from which it's easier to reconstruct 1009 00:38:53,670 --> 00:38:56,020 the more complicated notion of information, 1010 00:38:56,020 --> 00:38:58,800 meaning, for instance, we talk about memory traces, 1011 00:38:58,800 --> 00:39:01,090 and we build it up more and more complicated. 1012 00:39:01,090 --> 00:39:04,350 So, it's a very versatile, rich, confusing, 1013 00:39:04,350 --> 00:39:07,760 but key notion for understanding the world information 1014 00:39:07,760 --> 00:39:11,430 because the world is made by relations, not by things. 1015 00:39:11,430 --> 00:39:13,280 - In reality, it's not what it seems. 1016 00:39:13,280 --> 00:39:14,113 There's a passage that I love, 1017 00:39:14,113 --> 00:39:15,930 and I even told you about it after I read it, 1018 00:39:15,930 --> 00:39:17,630 because you go through so much of the book 1019 00:39:17,630 --> 00:39:21,260 explaining the historical context of quantum gravity 1020 00:39:21,260 --> 00:39:24,190 and explaining the concepts in very easy-to-follow terms, 1021 00:39:24,190 --> 00:39:26,350 which I appreciate, and then later in the book, 1022 00:39:26,350 --> 00:39:29,170 you say, "If, dear reader, you have found the journey 1023 00:39:29,170 --> 00:39:31,550 so far a little rough, hold on tighter 1024 00:39:31,550 --> 00:39:34,390 because we're now flying between voids of air." 1025 00:39:34,390 --> 00:39:36,957 And then you get into your new ideas, which you said, 1026 00:39:36,957 --> 00:39:39,090 "If the ideas seem confused, 1027 00:39:39,090 --> 00:39:41,640 it's because the person with the confused mind is me." 1028 00:39:41,640 --> 00:39:44,890 First of all, that's something I don't often see 1029 00:39:44,890 --> 00:39:48,010 in popular science books, is the warning to the reader, 1030 00:39:48,010 --> 00:39:50,870 like, it's okay to be shaken by this, 1031 00:39:50,870 --> 00:39:52,520 it's okay to not fully get it. 1032 00:39:52,520 --> 00:39:55,290 So, you gave this warning, and then you expressed ideas 1033 00:39:55,290 --> 00:39:58,570 that you personally don't have a full concept of. 1034 00:39:58,570 --> 00:40:00,870 Can you explain a little bit about what that's like, 1035 00:40:00,870 --> 00:40:04,200 going into territory that is less historically sound 1036 00:40:04,200 --> 00:40:06,540 and more speculative, and putting your own ideas out 1037 00:40:06,540 --> 00:40:07,640 on the line like that? 1038 00:40:08,800 --> 00:40:11,371 - There is a lot about the world we understand, 1039 00:40:11,371 --> 00:40:13,320 and there's a lot we don't understand. 1040 00:40:13,320 --> 00:40:15,670 It doesn't make much sense 1041 00:40:15,670 --> 00:40:17,630 what we too often do, in my opinion, 1042 00:40:17,630 --> 00:40:19,510 which is to pretend that we understand 1043 00:40:19,510 --> 00:40:21,780 the part we don't understand. 1044 00:40:21,780 --> 00:40:24,480 University professors that teach and lecture on physics, 1045 00:40:24,480 --> 00:40:26,270 they shouldn't pretend that they know everything about it. 1046 00:40:26,270 --> 00:40:28,910 They don't know about it, and they may be wrong. 1047 00:40:28,910 --> 00:40:30,760 I mean, they might be teaching things which are wrong, 1048 00:40:30,760 --> 00:40:32,803 so they should say, look, this is what we understand, 1049 00:40:32,803 --> 00:40:34,760 this is what I understand, 1050 00:40:34,760 --> 00:40:37,171 and be aware that there might be something wrong, 1051 00:40:37,171 --> 00:40:38,750 and if there's something confusing, 1052 00:40:38,750 --> 00:40:41,030 it might well be because it is confusing 1053 00:40:41,030 --> 00:40:43,200 or because a person is confused 1054 00:40:43,200 --> 00:40:44,900 or because the community is confused. 1055 00:40:44,900 --> 00:40:46,370 A good example is quantum mechanics. 1056 00:40:46,370 --> 00:40:49,320 Quantum mechanics is a hundred years old, 1057 00:40:49,320 --> 00:40:50,810 spectacularly successful, 1058 00:40:50,810 --> 00:40:53,220 used in technological applications everywhere, 1059 00:40:53,220 --> 00:40:54,850 but it's still confusing, 1060 00:40:54,850 --> 00:40:56,840 and the fact it's confusing may be good 1061 00:40:56,840 --> 00:40:59,830 because it may be that we still haven't got something, 1062 00:40:59,830 --> 00:41:01,630 some right way of looking at it, 1063 00:41:01,630 --> 00:41:03,450 so let's say it's confusing. 1064 00:41:03,450 --> 00:41:06,190 I think this makes, also, things easier 1065 00:41:06,190 --> 00:41:09,540 for the student at university or for the reader of a book 1066 00:41:09,540 --> 00:41:13,509 who is not presented this, you know, 1067 00:41:13,509 --> 00:41:18,130 both white, clean piece of stone saying, this is it, period. 1068 00:41:18,130 --> 00:41:19,340 We are humans. 1069 00:41:19,340 --> 00:41:21,710 Science is a human activity, like everything else. 1070 00:41:21,710 --> 00:41:24,606 It's dirty, it's imprecise, there are holes, 1071 00:41:24,606 --> 00:41:27,210 so I think it's better to present what it is. 1072 00:41:27,210 --> 00:41:29,260 - I connected with the idea that you yourself 1073 00:41:29,260 --> 00:41:30,867 are struggling with these ideas, 1074 00:41:30,867 --> 00:41:33,410 and when you read a book by an expert on any subject, 1075 00:41:33,410 --> 00:41:35,700 you assume the expert knows everything, 1076 00:41:35,700 --> 00:41:37,250 and for you to say later in the book, you know, 1077 00:41:37,250 --> 00:41:39,500 here's what I'm grappling with, it helps. 1078 00:41:39,500 --> 00:41:40,960 I think it helps the reader understand 1079 00:41:40,960 --> 00:41:42,120 that this is a difficult, 1080 00:41:42,120 --> 00:41:44,020 complex pursuit. - Yeah, my book, 1081 00:41:44,020 --> 00:41:46,860 my books are a little bit different in spirit 1082 00:41:46,860 --> 00:41:50,860 from most popular science books because they also are aimed 1083 00:41:50,860 --> 00:41:53,930 at a slightly different audience, and in fact, 1084 00:41:53,930 --> 00:41:57,910 I've remarked, from the reactions that I get, 1085 00:41:57,910 --> 00:42:01,830 that the typical reader of science books 1086 00:42:01,830 --> 00:42:05,790 likes my books less, and the people who like my book 1087 00:42:05,790 --> 00:42:07,420 are a little on the extreme sides, 1088 00:42:07,420 --> 00:42:10,460 are either people who know zero about science 1089 00:42:10,460 --> 00:42:12,400 or people who know a lot about science. 1090 00:42:12,400 --> 00:42:14,660 And I understand the reason because I think, 1091 00:42:14,660 --> 00:42:16,150 at these two extreme categories, 1092 00:42:16,150 --> 00:42:19,000 when I'm talking about them, the typical science book, 1093 00:42:19,000 --> 00:42:21,630 it's written for somebody who wants to know more and more 1094 00:42:21,630 --> 00:42:23,750 and more and more and more about some domain, 1095 00:42:23,750 --> 00:42:25,587 so you give more details, you give more information. 1096 00:42:25,587 --> 00:42:27,550 You say, "Oh, and we know that, and we know that, 1097 00:42:27,550 --> 00:42:30,390 and we know that," and you know, there are kids, 1098 00:42:30,390 --> 00:42:32,290 nerds that really want to know more and more and more 1099 00:42:32,290 --> 00:42:35,290 about the neutrinos and all the possible details about that. 1100 00:42:35,290 --> 00:42:36,890 I don't do that, I do the opposite. 1101 00:42:36,890 --> 00:42:38,980 I take away, I take away, I take away. 1102 00:42:38,980 --> 00:42:41,240 I strip away as much as possible, 1103 00:42:41,240 --> 00:42:44,800 trying to reduce to what seems to be the core 1104 00:42:44,800 --> 00:42:47,470 that we have understood about something 1105 00:42:47,470 --> 00:42:50,210 and to present it in a way that it stays together, 1106 00:42:50,210 --> 00:42:53,757 it holds on, and allows the reader to understand what it is 1107 00:42:53,757 --> 00:42:57,000 and what seems to me the real thing we have understood. 1108 00:42:57,000 --> 00:42:58,110 And then, of course, 1109 00:42:58,110 --> 00:43:00,060 those who know nothing about science, they like it, 1110 00:43:00,060 --> 00:43:01,890 because they say, "Oh, great, I get to that, yeah," 1111 00:43:01,890 --> 00:43:04,820 and those who know a lot about science also like it, 1112 00:43:04,820 --> 00:43:06,410 because they say, "Oh, wow, that's a good way 1113 00:43:06,410 --> 00:43:08,220 of doing things, maybe I didn't think this way, 1114 00:43:08,220 --> 00:43:09,410 maybe I was thinking the other way. 1115 00:43:09,410 --> 00:43:11,910 That's a new perspective on things." 1116 00:43:11,910 --> 00:43:14,047 And a lot of my best colleagues tell me, 1117 00:43:14,047 --> 00:43:16,310 "Ah, I have read your book, wow! 1118 00:43:16,310 --> 00:43:18,140 I didn't think about this way of putting it. 1119 00:43:18,140 --> 00:43:20,070 Great, great, I learned something." 1120 00:43:20,070 --> 00:43:23,150 Even my greatest enemy, the chief of the opposite, you know, 1121 00:43:23,150 --> 00:43:26,690 band theoretical physics, who is a Nobel Prize winner, 1122 00:43:26,690 --> 00:43:29,720 sent a message to me and said, "Fantastic, I loved it." 1123 00:43:29,720 --> 00:43:31,560 But the students of physics, 1124 00:43:31,560 --> 00:43:34,350 who've just studied that at school, 1125 00:43:34,350 --> 00:43:35,980 reads what I'm saying and knows, 1126 00:43:35,980 --> 00:43:37,350 because they say, "Wait a minute, I mean, 1127 00:43:37,350 --> 00:43:38,580 there's all missing here." 1128 00:43:38,580 --> 00:43:40,437 I got an email saying, 1129 00:43:40,437 --> 00:43:44,330 "You talk about quantum mechanics in the seven lessons. 1130 00:43:44,330 --> 00:43:46,420 You don't even mention the Schrödinger equation." 1131 00:43:46,420 --> 00:43:47,396 I thought, yeah, that's right, 1132 00:43:47,396 --> 00:43:48,881 I don't mention the Schrödinger equation, 1133 00:43:48,881 --> 00:43:50,480 but that's not the core. - The right story. 1134 00:43:50,480 --> 00:43:53,340 - Right, so yes, and this connects to your question, 1135 00:43:53,340 --> 00:43:55,900 what you were saying before, because to do that, 1136 00:43:55,900 --> 00:43:58,640 you need to understand something all the way through. 1137 00:43:58,640 --> 00:44:02,020 So, once we have totally digested something, 1138 00:44:02,020 --> 00:44:04,930 then you can just, bingo, you know, in one phrase. 1139 00:44:04,930 --> 00:44:06,490 - You can whittle it down to the essence. 1140 00:44:06,490 --> 00:44:07,790 - To the essence, right? - Yeah. 1141 00:44:07,790 --> 00:44:09,207 - I mean, take Copernicus. 1142 00:44:09,207 --> 00:44:11,480 If you read the book of Copernicus, 1143 00:44:11,480 --> 00:44:16,400 300 pages of calculations, detail, geometry, perspective. 1144 00:44:16,400 --> 00:44:18,987 It's horrendously complicated, then the equant, 1145 00:44:18,987 --> 00:44:21,697 the epicycles still, and then this and this and that, 1146 00:44:21,697 --> 00:44:25,100 and to make this complicated, and the moon is complicated. 1147 00:44:25,100 --> 00:44:27,960 What is it, 400 years have gone from Copernicus? 1148 00:44:27,960 --> 00:44:30,410 Now we have digested everything, can say it in two lines, 1149 00:44:30,410 --> 00:44:31,917 the earth is spinning 1150 00:44:31,917 --> 00:44:33,760 and is orbiting around the sun. 1151 00:44:33,760 --> 00:44:36,950 That's what Copernicus has qualified, so it's totally clear. 1152 00:44:36,950 --> 00:44:39,540 It's strange if you think about we are actually moving. 1153 00:44:39,540 --> 00:44:41,020 It's revolutionary. 1154 00:44:41,020 --> 00:44:42,127 It changes everything. 1155 00:44:42,127 --> 00:44:43,960 The earth isn't violent, like the others, 1156 00:44:43,960 --> 00:44:45,820 but it can be said in two lines. 1157 00:44:45,820 --> 00:44:48,080 Once we have really understood something, 1158 00:44:48,080 --> 00:44:49,650 at the end, we can say it in two lines 1159 00:44:49,650 --> 00:44:52,610 in a way that has it, has it really, 1160 00:44:52,610 --> 00:44:54,140 and the people understand what it is. 1161 00:44:54,140 --> 00:44:56,640 So, my ambition, but we're not there, 1162 00:44:56,640 --> 00:44:59,450 would be to do the same I just did with Copernicus, 1163 00:44:59,450 --> 00:45:01,390 the same with, you know, the standard models, 1164 00:45:01,390 --> 00:45:03,990 special relativity, general relativity, quantum mechanics, 1165 00:45:03,990 --> 00:45:05,820 quantum field theory, quantum gravity. 1166 00:45:05,820 --> 00:45:08,007 - You said in one piece you wrote, 1167 00:45:08,007 --> 00:45:09,750 "Sometimes dreams come true. 1168 00:45:09,750 --> 00:45:11,820 I felt there was a story about the adventure 1169 00:45:11,820 --> 00:45:13,440 of physics that had to be told, 1170 00:45:13,440 --> 00:45:15,420 but I thought people were not interested," 1171 00:45:15,420 --> 00:45:16,410 but you were wrong. 1172 00:45:16,410 --> 00:45:18,610 You were dead wrong because a lot of people were interested. 1173 00:45:18,610 --> 00:45:20,450 You know, millions of people have read your book. 1174 00:45:20,450 --> 00:45:22,890 It's translated into dozens of languages. 1175 00:45:22,890 --> 00:45:23,900 What do you think you got wrong 1176 00:45:23,900 --> 00:45:26,542 about estimating people's interest in this subject matter? 1177 00:45:26,542 --> 00:45:29,480 - (laughs) It was not just me wrong, 1178 00:45:29,480 --> 00:45:31,870 the "Seven Brief Lessons on Physics" 1179 00:45:31,870 --> 00:45:35,000 was printed in about 5,000 copies. 1180 00:45:35,000 --> 00:45:37,360 That was the estimate of the publisher 1181 00:45:37,360 --> 00:45:39,020 that was going to sell. - Yeah. 1182 00:45:39,020 --> 00:45:40,930 Do you think it was because you whittled down 1183 00:45:40,930 --> 00:45:43,110 to the essence and you left out the equations? 1184 00:45:43,110 --> 00:45:45,010 - No, I think it's because, 1185 00:45:45,010 --> 00:45:47,830 mostly because of the last chapter of the seventh. 1186 00:45:47,830 --> 00:45:49,980 I think that's what made the book. 1187 00:45:49,980 --> 00:45:52,550 It's a book that is not just about physics, 1188 00:45:52,550 --> 00:45:55,590 it's a book that tries to go down to the essence 1189 00:45:55,590 --> 00:45:57,580 and then asks the question, all right, 1190 00:45:57,580 --> 00:45:59,100 so what does it mean for us? 1191 00:45:59,100 --> 00:46:02,730 How does it reflect on the way we see ourself 1192 00:46:02,730 --> 00:46:06,010 and the way we think about the material, the physical world, 1193 00:46:06,010 --> 00:46:08,370 and our, let me use a strong word, spiritual world. 1194 00:46:08,370 --> 00:46:11,270 Let me tell you my interpretation of that. 1195 00:46:11,270 --> 00:46:14,400 I and my friends, and many people around me, 1196 00:46:14,400 --> 00:46:18,300 share a view of the world which is not much known 1197 00:46:18,300 --> 00:46:21,290 by a large majority of the population, 1198 00:46:21,290 --> 00:46:25,280 and it's a view of the world that is neither 1199 00:46:25,280 --> 00:46:27,060 the world is made by little atoms 1200 00:46:27,060 --> 00:46:29,770 bouncing with one another and that's it, 1201 00:46:29,770 --> 00:46:32,060 emotions, the sense of lives, whatever, 1202 00:46:32,060 --> 00:46:34,230 that's bullshit that comes later. 1203 00:46:34,230 --> 00:46:36,310 It's neither that, but it's neither 1204 00:46:37,200 --> 00:46:39,010 the material world is irrelevant, 1205 00:46:39,010 --> 00:46:43,580 there is a spiritual world, with God, morality and things, 1206 00:46:43,580 --> 00:46:45,930 that's what the reality is. 1207 00:46:45,930 --> 00:46:48,710 Somehow, a lot of people are unhappy with both 1208 00:46:48,710 --> 00:46:51,600 because they don't believe the spiritual world 1209 00:46:51,600 --> 00:46:54,110 too much anymore because we're in a secular society, 1210 00:46:54,110 --> 00:46:56,890 which doesn't hold anymore for a large number of people, 1211 00:46:56,890 --> 00:46:59,650 but neither people find convincing, 1212 00:46:59,650 --> 00:47:02,620 a sort of cold and ground cynicism, 1213 00:47:02,620 --> 00:47:06,120 which has no hold for meaning, for emotion, 1214 00:47:06,120 --> 00:47:08,830 for our aim, for what we are thinking 1215 00:47:08,830 --> 00:47:10,600 and desiring and suffering. 1216 00:47:10,600 --> 00:47:13,763 So, the fact that somehow people find in my book 1217 00:47:13,763 --> 00:47:15,520 a perspective where the two things 1218 00:47:15,520 --> 00:47:16,850 can very well stay together, 1219 00:47:16,850 --> 00:47:18,790 and there's no contradiction between one another, 1220 00:47:18,790 --> 00:47:22,527 is when a lot of people jump in and say, 1221 00:47:22,527 --> 00:47:24,890 "Oh," but then there are people who can think 1222 00:47:24,890 --> 00:47:27,360 that what matters for me is my emotions, 1223 00:47:27,360 --> 00:47:29,390 but also, there's nothing in contradiction 1224 00:47:29,390 --> 00:47:30,880 with fundamental science there. 1225 00:47:30,880 --> 00:47:32,490 I think that this is the bringing together 1226 00:47:32,490 --> 00:47:33,860 that made people react. 1227 00:47:33,860 --> 00:47:37,060 - And regarding this goal that you have in your writing 1228 00:47:37,060 --> 00:47:40,140 of getting to the essence of a concept, 1229 00:47:40,140 --> 00:47:42,110 I would think this would be uniquely challenging 1230 00:47:42,110 --> 00:47:44,100 when you're talking about something like time 1231 00:47:44,100 --> 00:47:47,940 because the average person will probably talk about time 1232 00:47:47,940 --> 00:47:49,480 at least once in a typical day. 1233 00:47:49,480 --> 00:47:51,890 So, there must be a lot that you need to strip away 1234 00:47:51,890 --> 00:47:54,390 because the average person has a lot of assumptions 1235 00:47:54,390 --> 00:47:56,970 that they're making about this word, time. 1236 00:47:56,970 --> 00:47:59,630 Can you tell us about what that process was like 1237 00:47:59,630 --> 00:48:01,630 when you're describing time? 1238 00:48:01,630 --> 00:48:05,300 - I wrote a book just uniquely, entirely about time, 1239 00:48:05,300 --> 00:48:07,450 and that was not an easy-to-write book 1240 00:48:07,450 --> 00:48:10,760 because exactly for the reason you're asking. 1241 00:48:10,760 --> 00:48:12,390 When I decided how to write this book, 1242 00:48:12,390 --> 00:48:14,443 I exactly asked myself this question. 1243 00:48:15,460 --> 00:48:18,500 And so, the first half, the longest half of the book, 1244 00:48:18,500 --> 00:48:21,500 one chapter after chapter demolishing something 1245 00:48:21,500 --> 00:48:23,370 we take for granted, our time, 1246 00:48:23,370 --> 00:48:25,600 and on good grounds, on things we know. 1247 00:48:25,600 --> 00:48:28,020 So, we think that time has this property, and you know, 1248 00:48:28,020 --> 00:48:30,150 it seems obvious to be that, that's the way we think, 1249 00:48:30,150 --> 00:48:32,550 and now I tell you it's not the case, 1250 00:48:32,550 --> 00:48:34,730 and I show why we know it's not the case. 1251 00:48:34,730 --> 00:48:37,392 So, the first part of the book, in part, 1252 00:48:37,392 --> 00:48:40,320 it's just a way of telling Boltzmann's theory, 1253 00:48:40,320 --> 00:48:42,480 of telling Einstein's special relativity, 1254 00:48:42,480 --> 00:48:45,310 putting the various pieces of the story together, 1255 00:48:45,310 --> 00:48:47,120 but not just for talking about physics, 1256 00:48:47,120 --> 00:48:49,060 for talking, look, what this implies 1257 00:48:49,060 --> 00:48:50,940 with respect to our notion of time. 1258 00:48:50,940 --> 00:48:54,270 Special relativity definitely changes our notion of time. 1259 00:48:54,270 --> 00:48:57,400 Notion of present everywhere in the universe doesn't hold, 1260 00:48:57,400 --> 00:48:59,190 but it's hard to think of the world without a notion 1261 00:48:59,190 --> 00:49:00,940 of present everywhere in the universe. 1262 00:49:00,940 --> 00:49:03,560 The question, what is going on right now on Andromeda, 1263 00:49:03,560 --> 00:49:05,580 the galaxy, is meaningless. 1264 00:49:05,580 --> 00:49:07,940 There's no meaning, what is going on right now. 1265 00:49:07,940 --> 00:49:09,850 There's no now in Andromeda. 1266 00:49:09,850 --> 00:49:12,990 It's like asking, what is going on here in Beijing? 1267 00:49:12,990 --> 00:49:14,800 We're not in Beijing, so it's not here in Beijing, 1268 00:49:14,800 --> 00:49:16,010 Beijing is elsewhere. 1269 00:49:16,010 --> 00:49:18,960 The book was designed exactly 1270 00:49:18,960 --> 00:49:20,930 to address what you are saying, 1271 00:49:20,930 --> 00:49:24,770 to take away, one by one, the suppositions of people 1272 00:49:24,770 --> 00:49:27,830 that the people give for granted in science. 1273 00:49:27,830 --> 00:49:30,503 Some of my colleagues which are very reflective, 1274 00:49:30,503 --> 00:49:32,590 a written book, there's absolutely nothing they learn 1275 00:49:32,590 --> 00:49:35,220 because they have gone through that, 1276 00:49:35,220 --> 00:49:36,770 but there are a lot of my colleagues 1277 00:49:36,770 --> 00:49:39,270 that teach special relativity and never have stopped 1278 00:49:39,270 --> 00:49:41,140 in thinking what, actually, they're teaching, 1279 00:49:41,140 --> 00:49:42,350 and I think that's wrong. 1280 00:49:42,350 --> 00:49:45,390 I mean, physics is interesting because it tells us something 1281 00:49:45,390 --> 00:49:48,480 about the world, not just because you write equations, 1282 00:49:48,480 --> 00:49:49,910 and then you make a prediction 1283 00:49:49,910 --> 00:49:51,520 and it matches with what you measured. 1284 00:49:51,520 --> 00:49:53,283 - Are you yet at a stage where you can give 1285 00:49:53,283 --> 00:49:56,370 just this one or two sentence definitions 1286 00:49:56,370 --> 00:49:58,523 that's the core of what time is? 1287 00:49:59,450 --> 00:50:02,370 - No, with time, it's very complicated, (laughs) 1288 00:50:02,370 --> 00:50:04,720 and the reason is because we haven't got to the end 1289 00:50:04,720 --> 00:50:06,350 of understanding it. 1290 00:50:06,350 --> 00:50:07,930 There are things about time 1291 00:50:07,930 --> 00:50:09,610 which I think were generally confused. 1292 00:50:09,610 --> 00:50:12,550 A lot of things we have figured out with total clarity, 1293 00:50:12,550 --> 00:50:14,440 like the nonexistence of a present 1294 00:50:14,440 --> 00:50:15,650 everywhere in the universe, 1295 00:50:15,650 --> 00:50:18,180 but there are issues about how to think about time 1296 00:50:18,180 --> 00:50:20,240 in a wholly consistent way with everything we know, 1297 00:50:20,240 --> 00:50:21,850 which I don't think we'll figure out. 1298 00:50:21,850 --> 00:50:24,730 Even the direction of time is implicated 1299 00:50:24,730 --> 00:50:26,830 because we have connected it to entropy, 1300 00:50:26,830 --> 00:50:28,390 to the microscopic description, 1301 00:50:28,390 --> 00:50:29,783 but there are definitely holes 1302 00:50:29,783 --> 00:50:31,800 in our understanding, in my opinion. 1303 00:50:31,800 --> 00:50:33,530 - I found that book, "The Order of Time", 1304 00:50:33,530 --> 00:50:37,480 to really make my brain meld and squish in other directions. 1305 00:50:37,480 --> 00:50:39,970 I was listening to the audio book, and at one point, 1306 00:50:39,970 --> 00:50:44,030 I was rushing somewhere, and something you wrote about time 1307 00:50:44,030 --> 00:50:45,930 made me think, why am I rushing anywhere, 1308 00:50:45,930 --> 00:50:48,280 a rush is an illusion. (Carlo laughing) 1309 00:50:48,280 --> 00:50:50,450 So, I appreciated your writing of that book. 1310 00:50:50,450 --> 00:50:53,610 I also really liked Benedict Cumberbatch reading it to me. 1311 00:50:53,610 --> 00:50:56,150 That was a nice experience. 1312 00:50:56,150 --> 00:50:59,161 Boy, it helps when these concepts are- 1313 00:50:59,161 --> 00:51:00,643 - He's astonishingly good. - Are so mind-bending. 1314 00:51:00,643 --> 00:51:01,960 - Yeah, he's really good. - Yes, yes, 1315 00:51:01,960 --> 00:51:04,487 I've been listening to his voice and saying, 1316 00:51:04,487 --> 00:51:05,987 "Wow, who wrote these wonderful things," 1317 00:51:05,987 --> 00:51:09,150 because it's too good for, it's certainly not me. 1318 00:51:09,150 --> 00:51:11,660 He has a way of making it a principle, 1319 00:51:11,660 --> 00:51:13,990 but also, it's like it's talking to you 1320 00:51:13,990 --> 00:51:16,324 and telling you like a friend- 1321 00:51:16,324 --> 00:51:18,980 - Yeah, but we actually have another student question 1322 00:51:18,980 --> 00:51:20,550 about your books. - Yeah. 1323 00:51:20,550 --> 00:51:23,080 This question was sent in by a PhD student 1324 00:51:23,080 --> 00:51:24,400 here at Perimeter. 1325 00:51:24,400 --> 00:51:27,780 - This is Mac Du Shen, a student at IQC in Perimeter, 1326 00:51:27,780 --> 00:51:29,060 writing, how did you first get started 1327 00:51:29,060 --> 00:51:30,408 into writing science books, 1328 00:51:30,408 --> 00:51:32,850 and how has that writing helped your own research? 1329 00:51:32,850 --> 00:51:34,340 Do you find writing a technical paper 1330 00:51:34,340 --> 00:51:36,513 or a more accessible book more challenging? 1331 00:51:37,950 --> 00:51:41,000 - Probably a book for a general audience. 1332 00:51:41,000 --> 00:51:42,970 You write a paper, a scientific paper, 1333 00:51:42,970 --> 00:51:44,810 after you've figured something out. 1334 00:51:44,810 --> 00:51:47,060 So, you just get confused in a problem, 1335 00:51:47,060 --> 00:51:51,040 and either alone or with some somebody else in physics, 1336 00:51:51,040 --> 00:51:53,110 we worked mostly in little groups, 1337 00:51:53,110 --> 00:51:55,940 two or three in theoretical physics, you sort of come out, 1338 00:51:55,940 --> 00:51:57,580 and at some point, it's clear, 1339 00:51:57,580 --> 00:51:58,770 and then you write it down, 1340 00:51:58,770 --> 00:52:00,590 and you write down what you've understood. 1341 00:52:00,590 --> 00:52:02,680 So, the writing is relatively easy. 1342 00:52:02,680 --> 00:52:05,580 I'm picky, I'm complicated in writing scientific articles. 1343 00:52:05,580 --> 00:52:07,810 I try to write them clear, 1344 00:52:07,810 --> 00:52:10,310 so I spend time writing and rewriting and rewriting, 1345 00:52:10,310 --> 00:52:13,180 perhaps more than what I should or could. 1346 00:52:13,180 --> 00:52:16,220 But the writing is, you know what you're saying exactly, 1347 00:52:16,220 --> 00:52:17,950 while when you're writing a book, 1348 00:52:17,950 --> 00:52:19,660 you still don't know what you're saying. 1349 00:52:19,660 --> 00:52:23,270 You're picking up what you're saying in the writing itself, 1350 00:52:23,270 --> 00:52:25,600 and writing, for me, is a complicated process. 1351 00:52:25,600 --> 00:52:29,050 My books are the result of a large number of revisions 1352 00:52:29,050 --> 00:52:31,280 and a large number of cancellations, 1353 00:52:31,280 --> 00:52:33,960 because I say, no, this is not useful for what comes, 1354 00:52:33,960 --> 00:52:35,590 and that's just superfluous. 1355 00:52:35,590 --> 00:52:39,067 So, the same phrase, I rewrite it 10 times and say, 1356 00:52:39,067 --> 00:52:40,480 "No, that's not clear, I mean, 1357 00:52:40,480 --> 00:52:42,070 is there a way to say it better?" 1358 00:52:42,070 --> 00:52:43,930 That's the heart of writing for me. 1359 00:52:43,930 --> 00:52:45,090 - I was just gonna say, for you, 1360 00:52:45,090 --> 00:52:47,610 it seems that this must be particularly challenging 1361 00:52:47,610 --> 00:52:48,900 because you're not just writing 1362 00:52:48,900 --> 00:52:50,280 a book for the general public. 1363 00:52:50,280 --> 00:52:52,690 As you said, you're hoping that your book 1364 00:52:52,690 --> 00:52:54,730 will be influential for the general public, 1365 00:52:54,730 --> 00:52:57,060 and also for experts in the field, 1366 00:52:57,060 --> 00:52:59,610 even though the material is not technical 1367 00:52:59,610 --> 00:53:01,350 or maybe doesn't rely on math. 1368 00:53:01,350 --> 00:53:05,080 So, I would assume writing something that can be a good fit 1369 00:53:05,080 --> 00:53:08,070 for both of those audiences must be very challenging. 1370 00:53:08,070 --> 00:53:11,090 - Yes, it is, and I have these two readers in mind, 1371 00:53:11,090 --> 00:53:13,450 the super expert one who knows everything, 1372 00:53:13,450 --> 00:53:15,440 and the one who knows nothing, 1373 00:53:15,440 --> 00:53:19,060 which is good because thinking like the super expert one 1374 00:53:19,060 --> 00:53:21,930 is what, you know, warns me from not saying something, 1375 00:53:21,930 --> 00:53:25,247 which is, oh, if I say that, he's gonna complain, (chuckles) 1376 00:53:25,247 --> 00:53:28,050 and thinking about the typical grandmother 1377 00:53:28,050 --> 00:53:29,573 who doesn't know anything stops me from saying things, 1378 00:53:29,573 --> 00:53:31,270 oh, but that's too complicated, I mean, 1379 00:53:31,270 --> 00:53:32,950 how can anybody get this point? 1380 00:53:32,950 --> 00:53:34,640 So, I always have these struggles, 1381 00:53:34,640 --> 00:53:37,670 so this simplifies because it gives me guidance, 1382 00:53:37,670 --> 00:53:39,780 but yes, it's also a complication to try 1383 00:53:39,780 --> 00:53:42,660 because I'm putting my own ideas in the books, 1384 00:53:42,660 --> 00:53:45,210 mostly because it's my own perspective of things, 1385 00:53:45,210 --> 00:53:47,450 writing a book of quantum mechanics, 1386 00:53:47,450 --> 00:53:49,030 which is entirely from the perspectives 1387 00:53:49,030 --> 00:53:51,700 of Heisenberg, Born, Dirac, 1388 00:53:51,700 --> 00:53:54,790 rather than from the perspective of Schrödinger. 1389 00:53:54,790 --> 00:53:56,823 So, it's taken quantum mechanics because I think 1390 00:53:56,823 --> 00:53:58,440 it's the most interesting thing. 1391 00:53:58,440 --> 00:53:59,840 I'm not the only one, but there are people 1392 00:53:59,840 --> 00:54:01,571 who think different, who think, no, no, no, no, 1393 00:54:01,571 --> 00:54:03,090 quantum mechanics is all about the Schrödinger equation 1394 00:54:03,090 --> 00:54:06,400 and the wave function evolving, that's all there is. 1395 00:54:06,400 --> 00:54:07,440 I think that's wrong. 1396 00:54:07,440 --> 00:54:10,880 My books are a way of defending a perspective, 1397 00:54:10,880 --> 00:54:12,600 but the two things help one another 1398 00:54:12,600 --> 00:54:14,373 because in the moment in which you try 1399 00:54:14,373 --> 00:54:18,560 to explain something simple, you get clarity yourself. 1400 00:54:18,560 --> 00:54:21,020 I mean, for me, it's an exercise of science. 1401 00:54:21,020 --> 00:54:23,560 I feel I'm doing science when I'm doing that 1402 00:54:23,560 --> 00:54:25,130 and clarifying my mind, 1403 00:54:25,130 --> 00:54:26,960 and reading of the great masters, 1404 00:54:26,960 --> 00:54:29,680 who were infinitely better than me, I mean, reading Galileo, 1405 00:54:29,680 --> 00:54:31,500 when he wrote these books, 1406 00:54:31,500 --> 00:54:33,980 it seems to me he's doing exactly the same thing. 1407 00:54:33,980 --> 00:54:36,030 I mean, he's talking to people. 1408 00:54:36,030 --> 00:54:40,270 That's a book written for the cultivated person 1409 00:54:40,270 --> 00:54:43,120 of the European Renaissance in the 17th Century, 1410 00:54:43,120 --> 00:54:45,580 not for his colleagues, astronomers, 1411 00:54:45,580 --> 00:54:48,240 because it explain things one by one, 1412 00:54:48,240 --> 00:54:51,330 but obviously it's debating with his colleagues, 1413 00:54:51,330 --> 00:54:52,600 astronomers, in the book. 1414 00:54:52,600 --> 00:54:55,610 It's making the subtle points of the argumentation, 1415 00:54:55,610 --> 00:54:57,293 proving him right and them wrong, 1416 00:54:57,293 --> 00:55:00,010 and that's what makes that book so great. 1417 00:55:00,010 --> 00:55:01,500 Now, of course, I'm not Galileo, 1418 00:55:01,500 --> 00:55:04,450 and I'm not writing the dialogue of the two great systems, 1419 00:55:04,450 --> 00:55:06,440 but it's this kind of popular science, 1420 00:55:06,440 --> 00:55:07,890 which other people are doing, 1421 00:55:07,890 --> 00:55:11,960 which is presenting ideas in a way which are comprehensible 1422 00:55:11,960 --> 00:55:14,800 to defend these ideas, which I'm trying to do. 1423 00:55:14,800 --> 00:55:16,980 - Are you working on any books now? 1424 00:55:16,980 --> 00:55:19,769 - Yeah, I am, but I'm not sure I should talk about that. 1425 00:55:19,769 --> 00:55:21,770 - (laughs) Are you always working on one book or another? 1426 00:55:21,770 --> 00:55:24,030 - No, no, I have not been writing 1427 00:55:25,010 --> 00:55:26,750 for one year, or more. 1428 00:55:26,750 --> 00:55:28,280 I just stopped completely. 1429 00:55:28,280 --> 00:55:30,030 I am under strong pressure, of course, 1430 00:55:30,030 --> 00:55:33,050 from publishers and things for writing more. 1431 00:55:33,050 --> 00:55:34,260 Let me just give you this, 1432 00:55:34,260 --> 00:55:36,430 I'm not covering a large portion of physics, 1433 00:55:36,430 --> 00:55:37,950 I want to do the narration, 1434 00:55:37,950 --> 00:55:41,410 tell the story of how a theoretical physicist like me 1435 00:55:41,410 --> 00:55:43,050 gets into a specific problem, 1436 00:55:43,050 --> 00:55:44,570 gets fascinated by the problem, 1437 00:55:44,570 --> 00:55:47,140 works through and comes out with some ideas, 1438 00:55:47,140 --> 00:55:48,840 and is struggling on. 1439 00:55:48,840 --> 00:55:51,400 So, whether this particular thing 1440 00:55:51,400 --> 00:55:53,010 is right or wrong is irrelevant. 1441 00:55:53,010 --> 00:55:57,000 I want to tell how is theoretical science in the doing. 1442 00:55:57,000 --> 00:55:58,620 - Sort of humanizing the process 1443 00:55:58,620 --> 00:56:00,640 or putting a- - Yes, yes. 1444 00:56:00,640 --> 00:56:02,380 - Making it relatable to non-science. 1445 00:56:02,380 --> 00:56:05,130 - Yes, so what is actually going on, 1446 00:56:05,130 --> 00:56:08,220 including changing minds and realizing things didn't work, 1447 00:56:08,220 --> 00:56:10,560 and so on and so forth. 1448 00:56:10,560 --> 00:56:12,480 - I don't actually have any further questions. 1449 00:56:12,480 --> 00:56:14,810 We've kept you for more than an hour, I believe. 1450 00:56:14,810 --> 00:56:16,650 - Wonderful. - So, thank you so much 1451 00:56:16,650 --> 00:56:19,110 for chatting with us. - Thank you. 1452 00:56:19,110 --> 00:56:20,300 - I'll just ask a question 1453 00:56:20,300 --> 00:56:22,100 I always ask people when I interview them, 1454 00:56:22,100 --> 00:56:24,130 what keeps you up at night these days? 1455 00:56:24,130 --> 00:56:25,350 - Last night, I was awake 1456 00:56:25,350 --> 00:56:28,410 with (laughing) my going away. 1457 00:56:28,410 --> 00:56:30,120 - It was a relevant question. - Yeah. 1458 00:56:30,120 --> 00:56:33,610 There is a beautiful experiment in quantum gravity, 1459 00:56:33,610 --> 00:56:35,470 in fact, that's been proposed. 1460 00:56:35,470 --> 00:56:38,030 There are some people who are questioning the way 1461 00:56:38,030 --> 00:56:40,670 to think about that, and I think they're wrong. 1462 00:56:40,670 --> 00:56:44,590 So, I'm trying to find out a right theoretical description 1463 00:56:44,590 --> 00:56:46,790 of this experiment, and in doing that, 1464 00:56:46,790 --> 00:56:48,910 it's fun because it's basic physics, 1465 00:56:48,910 --> 00:56:52,540 but it's the writing and thinking I do in new ways, 1466 00:56:52,540 --> 00:56:54,810 and there are technical issues, technical problems, 1467 00:56:54,810 --> 00:56:57,550 so I keep going around these things here. 1468 00:56:57,550 --> 00:56:59,360 So, it's not a big, huge question, 1469 00:56:59,360 --> 00:57:00,980 it's a very small, specific question. 1470 00:57:00,980 --> 00:57:03,060 - Well, we'll have to have you back another time 1471 00:57:03,060 --> 00:57:05,460 so you can tell us, tell us the results of that. 1472 00:57:06,300 --> 00:57:08,260 So, thank you again, this has just been a pleasure. 1473 00:57:08,260 --> 00:57:09,580 - Thank you very much. - Thank you. 1474 00:57:09,580 --> 00:57:10,654 - That was very nice. 1475 00:57:10,654 --> 00:57:14,590 (light electronic music) 1476 00:57:14,590 --> 00:57:17,350 - Thanks for listening to Conversations at the Perimeter. 1477 00:57:17,350 --> 00:57:20,210 If you like what you hear, please help us spread the word. 1478 00:57:20,210 --> 00:57:23,050 Rate, review and subscribe to Conversations at the Perimeter 1479 00:57:23,050 --> 00:57:25,100 wherever you get your podcasts. 1480 00:57:25,100 --> 00:57:27,290 Every review helps us out a lot, 1481 00:57:27,290 --> 00:57:30,040 and it helps more science enthusiasts find us. 1482 00:57:30,040 --> 00:57:31,863 Thanks for being part of the equation. 1483 00:57:31,863 --> 00:57:35,280 (light electronic music)