Flocking together: the physics of sheep herding and pedestrian flows
In this episode of Physics World Stories, host Andrew Glester shepherds you through the fascinating world of crowd dynamics. While gazing at a flock of sheep or meandering through a busy street, you may not immediately think of the physics at play – but there is much more than you think. Give the episode a listen to discover the surprising science behind how animals and people move together in large groups.
The first guest, Philip Ball, a UK-based science writer, explores the principles that underpin the movement of sheep in flocks. Insights from physics can even be used to inform herding tactics, whereby dogs are guided – usually through whistles – to control flocks of sheep and direct them towards a chosen destination. For even more detail, check out Ball’s recent Physics World feature “Field work – the physics of sheep, from phase transitions to collective motion“.
Next, Alessandro Corbetta, from Eindhoven University of Technology in the Netherlands, talks about his research on pedestrian flow that won him an Ig Nobel Prize. Corbetta explains how his research field is helping us understand – and manage – the movements of human crowds in bustling spaces such as museums, transport hubs and stadia. Plus, he shares how winning the Ig Nobel has enabled the research to reach a far broader audience than he initially imagined.
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1 00:00:04,719 --> 00:00:07,040 Hello, and welcome to the Physics World Stories 2 00:00:07,040 --> 00:00:09,859 podcast. I'm Andre Glesser. And in this episode, 3 00:00:09,919 --> 00:00:12,660 we're gonna be exploring the physics of crowds. 4 00:00:13,814 --> 00:00:14,314 Specifically, 5 00:00:14,695 --> 00:00:17,254 or at least to begin with, looking at 6 00:00:17,254 --> 00:00:19,355 the physics of sheep movement. 7 00:00:19,814 --> 00:00:22,295 And whilst this is a slightly wooly topic, 8 00:00:22,295 --> 00:00:24,875 and you will find the odd sheep based 9 00:00:24,934 --> 00:00:25,914 joke in here, 10 00:00:26,429 --> 00:00:29,410 there is also some really intriguing physics 11 00:00:29,789 --> 00:00:31,949 not just a value to those who are 12 00:00:31,949 --> 00:00:35,070 animal herders but anyone interested in animal or 13 00:00:35,070 --> 00:00:36,130 human behavior 14 00:00:36,670 --> 00:00:38,829 later in the podcast we'll hear from someone 15 00:00:38,829 --> 00:00:41,825 who won for their work on human crowds 16 00:00:41,885 --> 00:00:43,265 the ignobel prize 17 00:00:43,645 --> 00:00:46,365 the prize given for research that makes you 18 00:00:46,365 --> 00:00:49,325 laugh and then think but on the physics 19 00:00:49,325 --> 00:00:51,804 world website you'll find an article by Philip 20 00:00:51,804 --> 00:00:55,265 Ball a science writer based in London entitled 21 00:00:55,760 --> 00:00:58,560 field work, the physics of sheep from phase 22 00:00:58,560 --> 00:00:59,060 transitions 23 00:00:59,520 --> 00:01:00,820 to collective motion. 24 00:01:01,280 --> 00:01:03,119 And through a window out of which I 25 00:01:03,119 --> 00:01:06,579 often gaze, there is a flock of sheep. 26 00:01:06,799 --> 00:01:07,780 I must admit 27 00:01:08,125 --> 00:01:10,125 at no point when I've looked at these 28 00:01:10,125 --> 00:01:12,765 sheep have I thought of physics. So I 29 00:01:12,765 --> 00:01:13,265 wondered 30 00:01:13,724 --> 00:01:16,784 quite why it had occurred to Philip Paul. 31 00:01:16,844 --> 00:01:19,004 So gazing out of that same window at 32 00:01:19,004 --> 00:01:20,765 that flock of sheep, I gave him a 33 00:01:20,765 --> 00:01:21,265 call. 34 00:01:22,420 --> 00:01:25,380 I've had a long interest in how ideas 35 00:01:25,380 --> 00:01:26,920 from physics can be, 36 00:01:27,859 --> 00:01:29,319 can be used to understand 37 00:01:29,780 --> 00:01:32,040 systems that don't sound at all like physics. 38 00:01:32,100 --> 00:01:32,600 And 39 00:01:32,980 --> 00:01:35,640 animal motion is one of them, actually, including 40 00:01:35,780 --> 00:01:37,000 the motion of people. 41 00:01:38,105 --> 00:01:40,584 So actually, years ago, 20 years ago, I 42 00:01:40,584 --> 00:01:41,564 wrote a book about, 43 00:01:42,025 --> 00:01:44,025 the this topic of how we could use 44 00:01:44,025 --> 00:01:45,724 ideas from physics to understand 45 00:01:46,105 --> 00:01:47,645 aspects of human society. 46 00:01:48,825 --> 00:01:50,025 And, you know, as I say in the 47 00:01:50,025 --> 00:01:52,444 piece, compared to trying to do that, 48 00:01:53,149 --> 00:01:55,729 trying to understand sheep might seem like, 49 00:01:56,030 --> 00:01:58,129 you know, an easy thing to do because, 50 00:01:58,670 --> 00:02:01,329 they have somewhat less, sophistication 51 00:02:02,030 --> 00:02:03,329 than, than humans. 52 00:02:04,759 --> 00:02:05,259 But 53 00:02:06,435 --> 00:02:09,235 it it's actually it's a very interesting problem 54 00:02:09,235 --> 00:02:11,555 to understand how sheep herd, but also there's 55 00:02:11,555 --> 00:02:14,435 this added twist that sheep are herded by 56 00:02:14,435 --> 00:02:14,935 dogs. 57 00:02:15,235 --> 00:02:17,495 You know? And that seems like a completely 58 00:02:17,794 --> 00:02:18,534 kind of 59 00:02:19,319 --> 00:02:22,040 idiosyncratic thing that is miles away from anything 60 00:02:22,040 --> 00:02:23,879 physics could handle, but it turns out that 61 00:02:23,879 --> 00:02:24,540 it isn't. 62 00:02:25,319 --> 00:02:27,719 And these models that are used, they're ones 63 00:02:27,719 --> 00:02:28,699 that have, 64 00:02:29,159 --> 00:02:31,580 that sort of have their roots in work 65 00:02:31,639 --> 00:02:32,139 on 66 00:02:32,504 --> 00:02:34,604 particularly on more obviously 67 00:02:34,985 --> 00:02:38,025 sort of collective flocking motions like, flocking of 68 00:02:38,025 --> 00:02:40,985 birds, like the schooling of fish. Things that, 69 00:02:40,985 --> 00:02:42,604 you know, when we look at them, 70 00:02:43,544 --> 00:02:45,724 there seems we we just kind of intuit 71 00:02:45,784 --> 00:02:47,324 that there has to be some 72 00:02:48,030 --> 00:02:50,669 deeper principle going on that gives them this 73 00:02:50,669 --> 00:02:51,569 kind of coherence, 74 00:02:52,750 --> 00:02:54,990 that, you know, doesn't seem to come from 75 00:02:54,990 --> 00:02:55,729 from individual 76 00:02:56,110 --> 00:02:56,610 animals. 77 00:02:57,229 --> 00:02:59,389 And in fact, I'd seen before I even 78 00:02:59,389 --> 00:03:01,250 encountered these papers, I'd seen, 79 00:03:01,790 --> 00:03:04,014 just, you know, video footage on on the 80 00:03:04,014 --> 00:03:04,915 web of 81 00:03:05,294 --> 00:03:05,794 sheep 82 00:03:06,495 --> 00:03:08,814 fluids. So it's got the kind of these 83 00:03:08,814 --> 00:03:11,474 aerial photos, probably drone photos of sheep, 84 00:03:12,415 --> 00:03:15,294 her you know, wandering around in fields, speeded 85 00:03:15,294 --> 00:03:15,794 up 86 00:03:16,349 --> 00:03:18,669 and kind of going through gates and, you 87 00:03:18,669 --> 00:03:20,990 know, going around obstacles and so on. And 88 00:03:20,990 --> 00:03:23,150 it's really weird to see it because it 89 00:03:23,150 --> 00:03:25,710 really does look like the flow of some 90 00:03:25,710 --> 00:03:28,289 kind of, you know, slightly granular fluid. 91 00:03:28,784 --> 00:03:30,944 So there too, if we see it if 92 00:03:30,944 --> 00:03:32,064 we look at it on the right sort 93 00:03:32,064 --> 00:03:34,004 of time scale and from the right perspective, 94 00:03:34,544 --> 00:03:36,625 you know, again, there's this sort of intuitive 95 00:03:36,625 --> 00:03:39,584 feeling that there's something there's some grand principle, 96 00:03:39,584 --> 00:03:42,539 there's some physics in this system. That's what 97 00:03:42,539 --> 00:03:44,620 this work that I was writing about is 98 00:03:44,620 --> 00:03:46,539 trying to explore. So I say I'm looking 99 00:03:46,539 --> 00:03:48,939 out the window, and there are a flock 100 00:03:48,939 --> 00:03:50,800 of sheep. You know, there's walls, 101 00:03:51,259 --> 00:03:51,759 there's 102 00:03:52,139 --> 00:03:52,639 hedges, 103 00:03:53,235 --> 00:03:56,594 There's occasionally the odd sheepdog. And at this 104 00:03:56,594 --> 00:03:59,235 time of year, when the tourists have gone, 105 00:03:59,235 --> 00:04:00,614 the sheep are sort of, 106 00:04:01,155 --> 00:04:03,235 yeah, just left to their own devices. When 107 00:04:03,235 --> 00:04:05,074 there are tourists here walking their dogs, the 108 00:04:05,074 --> 00:04:07,129 sheep are scared all over the place. But 109 00:04:07,129 --> 00:04:09,770 it's it's I've to be perfectly honest, as 110 00:04:09,770 --> 00:04:11,370 a bit of a nerd, I have enjoyed 111 00:04:11,370 --> 00:04:12,270 watching the sheep, 112 00:04:13,129 --> 00:04:14,810 more at this time of year where they're 113 00:04:14,810 --> 00:04:16,569 just left to their own devices, as I 114 00:04:16,569 --> 00:04:18,410 say, and they have this kind of well, 115 00:04:18,410 --> 00:04:20,175 yeah, they are a flock, aren't they? 116 00:04:20,654 --> 00:04:23,134 Yeah. It is. And, you know, what so 117 00:04:23,134 --> 00:04:24,814 so what does that mean? It, you know, 118 00:04:24,814 --> 00:04:26,754 it means there's a a load of them, 119 00:04:26,814 --> 00:04:28,654 but it means something more than that. It 120 00:04:28,654 --> 00:04:30,194 means that they are 121 00:04:30,495 --> 00:04:33,314 somehow interacting with an with each other 122 00:04:33,740 --> 00:04:35,199 to stay coherent. 123 00:04:36,139 --> 00:04:37,759 And that's something that 124 00:04:38,060 --> 00:04:39,199 pretty much all, 125 00:04:40,060 --> 00:04:43,100 groups of animals do or groups of living 126 00:04:43,100 --> 00:04:45,740 organisms. Actually, even cells do that. You can 127 00:04:45,740 --> 00:04:47,580 see it with bacteria. There are some people 128 00:04:47,580 --> 00:04:49,754 who develop models like this to try to 129 00:04:49,754 --> 00:04:52,235 understand bacteria and how they sort of flow 130 00:04:52,235 --> 00:04:54,314 around, and they too can kind of sense 131 00:04:54,314 --> 00:04:55,295 each other's presence. 132 00:04:56,634 --> 00:04:59,295 And, you know, I I I kind of 133 00:04:59,675 --> 00:05:01,435 we we if we think of how we 134 00:05:01,435 --> 00:05:03,660 move around in space, we're clearly doing that 135 00:05:03,660 --> 00:05:04,939 as well. We like to think, you know, 136 00:05:04,939 --> 00:05:07,259 we're all individuals. But if we're moving down 137 00:05:07,259 --> 00:05:09,500 a crowded pavement or something, then we are 138 00:05:09,500 --> 00:05:12,779 interacting with others. We're certainly, we're trying to 139 00:05:12,779 --> 00:05:14,939 avoid collisions if we're not staring at our 140 00:05:14,939 --> 00:05:16,879 phones. We're trying to avoid bumping into, 141 00:05:17,180 --> 00:05:17,840 each other. 142 00:05:18,375 --> 00:05:21,014 But also, occasionally, we might be moving with 143 00:05:21,014 --> 00:05:23,014 a group of friends or with family. And 144 00:05:23,014 --> 00:05:25,574 so there's a kind of attraction, a kind 145 00:05:25,574 --> 00:05:27,814 of cohesion there. We're trying to to stick 146 00:05:27,814 --> 00:05:28,314 together. 147 00:05:28,694 --> 00:05:31,275 So, you know, there are these these principles 148 00:05:31,975 --> 00:05:32,399 that 149 00:05:32,879 --> 00:05:33,860 aren't totally 150 00:05:34,160 --> 00:05:36,259 unlike the way inanimate 151 00:05:36,560 --> 00:05:37,060 particles 152 00:05:37,600 --> 00:05:38,419 might interact 153 00:05:38,720 --> 00:05:40,259 through forces of attraction 154 00:05:40,720 --> 00:05:43,839 and repulsion, repulsion being this tendency to avoid 155 00:05:43,839 --> 00:05:44,339 collisions. 156 00:05:45,544 --> 00:05:47,305 And and this was the kind of idea 157 00:05:47,305 --> 00:05:49,944 that, you know, lies behind all of these 158 00:05:49,944 --> 00:05:52,285 attempts to try to understand group motion. 159 00:05:53,225 --> 00:05:55,625 Is it is it something that we can 160 00:05:55,625 --> 00:05:56,125 describe 161 00:05:56,745 --> 00:05:59,460 just in terms of forces of attraction and 162 00:05:59,460 --> 00:06:01,160 repulsion between the individuals, 163 00:06:02,020 --> 00:06:02,520 who 164 00:06:03,060 --> 00:06:04,980 each of which, you know, have their own 165 00:06:04,980 --> 00:06:06,980 kind of agenda to some extent, but it 166 00:06:06,980 --> 00:06:08,900 may be a fairly simple agenda. I mean, 167 00:06:08,900 --> 00:06:10,500 even for us, if we're walking down a 168 00:06:10,500 --> 00:06:12,819 pavement, we're generally trying to get from one 169 00:06:12,819 --> 00:06:15,214 place to another, you know, probably as as 170 00:06:15,214 --> 00:06:16,595 as quickly as possible 171 00:06:17,294 --> 00:06:18,274 while navigating 172 00:06:18,574 --> 00:06:20,834 obstacles and while, you know, avoiding 173 00:06:21,694 --> 00:06:22,194 collisions. 174 00:06:23,134 --> 00:06:23,634 So 175 00:06:24,334 --> 00:06:24,834 that's 176 00:06:25,454 --> 00:06:28,819 that's a, in principle, that's a fairly simple 177 00:06:28,819 --> 00:06:29,319 situation 178 00:06:29,699 --> 00:06:31,540 to to try to model and, you know, 179 00:06:31,540 --> 00:06:33,540 that's kind of what you're probably seeing sheep 180 00:06:33,540 --> 00:06:35,620 do, except that there's, you know, there's also 181 00:06:35,620 --> 00:06:37,220 something else that I imagine you're kind of 182 00:06:37,220 --> 00:06:38,819 seeing them doing, which is, you know, they're 183 00:06:38,819 --> 00:06:40,259 not just trying to get from a to 184 00:06:40,259 --> 00:06:42,185 b. On the whole, what they tend to 185 00:06:42,185 --> 00:06:44,685 be doing is is wanting to to eat. 186 00:06:45,225 --> 00:06:47,384 They spend their most of their lives doing 187 00:06:47,384 --> 00:06:48,225 that, you know, 188 00:06:48,665 --> 00:06:50,205 chewing on on grass. 189 00:06:51,305 --> 00:06:53,464 So, you know, that's another aspect of the 190 00:06:53,464 --> 00:06:56,759 problem that's specific to grazing animals that they're 191 00:06:56,759 --> 00:06:58,759 not just trying to move. They will move 192 00:06:58,759 --> 00:07:00,759 occasionally, and in particular, they'll move to try 193 00:07:00,759 --> 00:07:03,259 to find more food, more grass. 194 00:07:04,279 --> 00:07:06,839 But there's that, there there's that sort of 195 00:07:06,839 --> 00:07:08,860 complex, you know, interplay between 196 00:07:09,444 --> 00:07:12,165 just trying to, you know, be left alone 197 00:07:12,165 --> 00:07:13,464 to graze, to eat, 198 00:07:13,845 --> 00:07:15,785 and moving around together. 199 00:07:16,165 --> 00:07:16,665 And 200 00:07:17,045 --> 00:07:18,345 with sheep in particular, 201 00:07:19,285 --> 00:07:20,745 as you say, they're nervous 202 00:07:21,045 --> 00:07:23,444 of other animals, particularly of dogs, but also 203 00:07:23,444 --> 00:07:26,189 of humans. So there's also that aspect. They're 204 00:07:26,189 --> 00:07:28,269 kind of looking out for what they might, 205 00:07:28,269 --> 00:07:29,810 you know, imagine are predators. 206 00:07:30,829 --> 00:07:32,849 So those are the kind of components 207 00:07:33,149 --> 00:07:35,310 of the behavior that need to go into 208 00:07:35,310 --> 00:07:36,849 trying to model this situation. 209 00:07:37,149 --> 00:07:38,370 As we've been talking, 210 00:07:38,735 --> 00:07:40,355 the sheep have gone from 211 00:07:41,055 --> 00:07:41,954 lying down 212 00:07:42,415 --> 00:07:42,915 behind 213 00:07:43,295 --> 00:07:45,454 a sort of hillock on the hillside, if 214 00:07:45,454 --> 00:07:46,814 you see what I mean. It's it's it's 215 00:07:46,814 --> 00:07:48,334 a a mound on the hillside, which is 216 00:07:48,334 --> 00:07:50,654 protecting them from the wind. That's why they're 217 00:07:50,654 --> 00:07:52,649 all there as far as I can see. 218 00:07:52,729 --> 00:07:54,329 Then the sun's come out, and they've all 219 00:07:54,329 --> 00:07:56,970 spread out across the field. Physics doesn't explain 220 00:07:56,970 --> 00:07:58,169 that, does it? I mean, apart from the 221 00:07:58,169 --> 00:07:59,149 sun coming out. 222 00:08:00,729 --> 00:08:02,509 Well, it it it 223 00:08:03,209 --> 00:08:04,910 I could see how it could 224 00:08:05,235 --> 00:08:07,394 in that, you know, if you were wanting 225 00:08:07,394 --> 00:08:07,894 to, 226 00:08:08,995 --> 00:08:11,254 to to include in a model like this, 227 00:08:11,714 --> 00:08:14,615 their wish to be in sunshine, 228 00:08:15,475 --> 00:08:15,975 then 229 00:08:16,354 --> 00:08:18,274 the you know, there's an attraction there. There's 230 00:08:18,274 --> 00:08:21,310 an attraction to a particular kind of, you 231 00:08:21,310 --> 00:08:22,990 know, you can model it as a as 232 00:08:22,990 --> 00:08:24,370 a force, as a field. 233 00:08:25,149 --> 00:08:25,889 I mean, 234 00:08:26,269 --> 00:08:27,970 there's literally a field as well. 235 00:08:28,350 --> 00:08:30,509 So you can see how you can, you 236 00:08:30,509 --> 00:08:33,070 know, build aspects like that into it. The 237 00:08:33,070 --> 00:08:35,549 other, interesting thing about sheep and about, you 238 00:08:35,549 --> 00:08:38,654 know, larger animals like that, which actually doesn't 239 00:08:38,654 --> 00:08:40,575 apply so much to us. You know, sheep 240 00:08:40,575 --> 00:08:43,534 are elongated. So from above, we're kind of, 241 00:08:43,534 --> 00:08:46,014 you know, circular blobs, and you can model 242 00:08:46,014 --> 00:08:47,554 us as circular particles. 243 00:08:47,934 --> 00:08:50,115 Sheep are kind of more like ellipsoidal 244 00:08:50,654 --> 00:08:51,154 particles. 245 00:08:52,629 --> 00:08:54,330 And so there's an orientational 246 00:08:54,710 --> 00:08:56,710 aspect to that. It's a bit like the 247 00:08:56,710 --> 00:08:57,850 contrast between, 248 00:08:58,470 --> 00:09:01,350 you know, simple atoms or or, you know, 249 00:09:01,350 --> 00:09:03,929 globular molecules and liquid crystals, 250 00:09:04,575 --> 00:09:07,134 which also have that tendency to kind of 251 00:09:07,134 --> 00:09:09,695 align, to respond to one another's presence by 252 00:09:09,695 --> 00:09:11,475 sort of aligning their their axis. 253 00:09:12,095 --> 00:09:14,335 And so, you know, that's a question we 254 00:09:14,335 --> 00:09:17,295 might ask and and the researchers have asked 255 00:09:17,295 --> 00:09:18,274 about sheep. 256 00:09:18,659 --> 00:09:21,379 Is there a a tendency to align? And 257 00:09:21,379 --> 00:09:23,940 if there is, then that looks a little 258 00:09:23,940 --> 00:09:24,919 bit like 259 00:09:25,299 --> 00:09:27,240 the way magnetic spins 260 00:09:27,700 --> 00:09:29,320 align in magnetic materials, 261 00:09:30,019 --> 00:09:32,100 and you can build that force into it 262 00:09:32,100 --> 00:09:33,764 as well. A force that, 263 00:09:34,965 --> 00:09:37,285 will make one sheep have a kind of 264 00:09:37,285 --> 00:09:39,545 tendency to align its body, 265 00:09:40,404 --> 00:09:42,884 with the direction of what its neighbors are 266 00:09:42,884 --> 00:09:43,945 doing. Why? 267 00:09:44,565 --> 00:09:46,745 Well, I I I guess I mean, certainly, 268 00:09:46,804 --> 00:09:49,009 if if you're if we're thinking about the 269 00:09:49,009 --> 00:09:50,389 way sheep move, 270 00:09:51,649 --> 00:09:52,850 you know, they seem to 271 00:09:53,490 --> 00:09:54,230 the the flocks, 272 00:09:54,769 --> 00:09:57,409 seem to occasionally to sort of wander as 273 00:09:57,409 --> 00:10:00,049 groups in the same direction. That's something that 274 00:10:00,049 --> 00:10:02,715 you just observe happening. So sheep, you know, 275 00:10:02,715 --> 00:10:04,735 have this tendency to follow one another. 276 00:10:05,595 --> 00:10:06,575 And if 277 00:10:07,514 --> 00:10:08,575 that's the case, 278 00:10:08,955 --> 00:10:10,955 they're clearly gonna have to be aligned in 279 00:10:10,955 --> 00:10:12,554 order to do that. So they're not, you 280 00:10:12,554 --> 00:10:14,475 know, literally, they're they're trying to align in 281 00:10:14,475 --> 00:10:15,535 the walking direction. 282 00:10:15,980 --> 00:10:18,539 So while they're moving, you know, they'll be 283 00:10:18,539 --> 00:10:20,779 trying to align. But also, you know, if 284 00:10:20,779 --> 00:10:22,000 they were in a dense 285 00:10:22,379 --> 00:10:24,299 flock and they were being, for example, if 286 00:10:24,299 --> 00:10:26,940 they were being shepherded by a dog, then 287 00:10:26,940 --> 00:10:29,259 again, they're they're one they're they're not gonna 288 00:10:29,259 --> 00:10:31,034 be wanting to bump into each other. 289 00:10:32,154 --> 00:10:34,475 So, you know, there's probably there too going 290 00:10:34,475 --> 00:10:36,475 to be a tendency to kind of line 291 00:10:36,475 --> 00:10:37,534 themselves up. 292 00:10:38,394 --> 00:10:40,394 So, you know, that it's really, 293 00:10:40,954 --> 00:10:43,754 just either a matter of, doing that in 294 00:10:43,754 --> 00:10:47,370 order to, coordinate their motions or doing it 295 00:10:47,370 --> 00:10:50,090 so that they can pack more efficiently in 296 00:10:50,090 --> 00:10:50,990 a small space. 297 00:10:51,690 --> 00:10:53,769 I do there's a a behavior that I 298 00:10:53,769 --> 00:10:55,370 observe here. I don't know if you've seen 299 00:10:55,370 --> 00:10:56,509 an answer to this, but, 300 00:10:57,210 --> 00:10:59,550 very regularly in the summer months, there's, 301 00:11:00,674 --> 00:11:02,674 you know, a tourist dog who should be 302 00:11:02,674 --> 00:11:04,035 on a lead isn't on a lead, but 303 00:11:04,035 --> 00:11:06,294 we'll we'll sketch over that particular issue. 304 00:11:07,554 --> 00:11:09,394 But one of the sheep gets isolated from 305 00:11:09,394 --> 00:11:10,375 the rest of the flock. 306 00:11:10,914 --> 00:11:13,750 Then the dog goes away and that sheep 307 00:11:13,830 --> 00:11:17,190 the isolated sheep then calls out and tries 308 00:11:17,190 --> 00:11:18,710 to find its way back to the to 309 00:11:18,710 --> 00:11:20,710 the flock. It well, it seems that they 310 00:11:20,710 --> 00:11:22,230 do. I mean, a lot of animals do, 311 00:11:22,470 --> 00:11:25,110 particularly if there's a predator around because it's 312 00:11:25,110 --> 00:11:26,870 the kind of safety in numbers thing, you 313 00:11:26,870 --> 00:11:29,324 know, that that actually a sheep on its 314 00:11:29,324 --> 00:11:31,964 own is gonna feel much more exposed than 315 00:11:31,964 --> 00:11:33,725 a sheep in a flock and particularly a 316 00:11:33,725 --> 00:11:35,884 sheep in the center of the flock. So, 317 00:11:35,884 --> 00:11:38,605 you know, there's clearly a, there's a sort 318 00:11:38,605 --> 00:11:40,524 of attraction if you like there for the 319 00:11:40,524 --> 00:11:42,444 sheep to a sort of cohesive force that 320 00:11:42,444 --> 00:11:44,464 will keep them together for safety. 321 00:11:44,980 --> 00:11:46,899 And, you know, more than that, that what 322 00:11:46,899 --> 00:11:48,340 you actually see in, 323 00:11:48,740 --> 00:11:51,220 sheep flocks and in other sometimes other groups 324 00:11:51,220 --> 00:11:53,559 of animals that are exposed to predators 325 00:11:54,100 --> 00:11:55,539 is they they all wanna be in the 326 00:11:55,539 --> 00:11:57,620 middle, which kind of makes sense, you know, 327 00:11:57,620 --> 00:11:58,360 that that's, 328 00:11:59,139 --> 00:12:00,519 that's the safest place. 329 00:12:00,875 --> 00:12:03,294 And so there's this kind of constant churn, 330 00:12:03,355 --> 00:12:04,495 you know, going on. 331 00:12:05,355 --> 00:12:06,475 And in fact, it's, 332 00:12:07,914 --> 00:12:11,034 some, biologists have, you know, talked about this 333 00:12:11,034 --> 00:12:13,375 in terms of this kind of selfish flock 334 00:12:13,620 --> 00:12:14,120 theory, 335 00:12:14,899 --> 00:12:16,340 where, you know, everyone wants to be in 336 00:12:16,340 --> 00:12:18,259 the middle. And so what what kind of 337 00:12:18,259 --> 00:12:18,759 dynamics, 338 00:12:19,299 --> 00:12:20,679 result from that? 339 00:12:21,379 --> 00:12:23,379 So, yeah, that that that, you know, if 340 00:12:23,379 --> 00:12:25,779 if if, an individual or small groups get 341 00:12:25,779 --> 00:12:28,504 isolated, then there is this sort of attraction 342 00:12:28,565 --> 00:12:30,184 to bring them back into the flock 343 00:12:30,805 --> 00:12:33,125 for the the the purposes of safety. In 344 00:12:33,125 --> 00:12:35,845 the selfish flock, my understanding is that at 345 00:12:35,845 --> 00:12:37,365 least it's the way it's talked about, I 346 00:12:37,365 --> 00:12:38,985 think, in the march of the penguins. 347 00:12:39,605 --> 00:12:42,004 They they take it in turns, and that's 348 00:12:42,004 --> 00:12:43,384 less selfish and more, 349 00:12:44,080 --> 00:12:46,240 altruistic, more part of the group kind of 350 00:12:46,240 --> 00:12:47,840 looking after each other. Is that just a 351 00:12:47,840 --> 00:12:49,279 kind of a nice way of looking at 352 00:12:49,279 --> 00:12:51,279 it? Well, that you know, that's a good 353 00:12:51,279 --> 00:12:53,299 question because it's quite possible, 354 00:12:53,919 --> 00:12:55,120 and I don't know if this is the 355 00:12:55,120 --> 00:12:58,245 case for penguins. I think it's more probably 356 00:12:58,304 --> 00:13:00,004 the case for for sheep, certainly. 357 00:13:00,384 --> 00:13:02,225 It's quite possible that if you have a 358 00:13:02,225 --> 00:13:05,684 model where there's the the the the individuals 359 00:13:05,824 --> 00:13:08,784 are moving around, they have this tendency to 360 00:13:08,784 --> 00:13:11,379 try to get into the center. That actually 361 00:13:11,379 --> 00:13:11,879 spontaneously 362 00:13:12,500 --> 00:13:14,419 out of that will come this kind of 363 00:13:14,419 --> 00:13:16,340 churn, this kind of turnover of who's on 364 00:13:16,340 --> 00:13:18,340 the edge. So it's not as though the 365 00:13:18,340 --> 00:13:20,100 individuals on the edge are kind of at 366 00:13:20,100 --> 00:13:21,480 any time consciously 367 00:13:21,779 --> 00:13:24,659 thinking, okay. I've had my turn now. You 368 00:13:24,659 --> 00:13:26,634 know, I've done my my my part to 369 00:13:26,634 --> 00:13:28,154 be on the edge now. Let me back 370 00:13:28,154 --> 00:13:29,995 in the middle. I don't think, it seem 371 00:13:30,074 --> 00:13:32,074 it seems unlikely that anything like that is 372 00:13:32,074 --> 00:13:34,334 going on. It seems more probable 373 00:13:34,794 --> 00:13:37,595 that something like this kind of behavior would 374 00:13:37,595 --> 00:13:38,654 emerge spontaneously 375 00:13:39,269 --> 00:13:42,070 simply from those movement and from those kind 376 00:13:42,070 --> 00:13:42,730 of psychological 377 00:13:43,430 --> 00:13:43,930 rules. 378 00:13:44,389 --> 00:13:45,990 And the other thing that seems to be 379 00:13:45,990 --> 00:13:48,330 spontaneous from what I can see is the 380 00:13:48,790 --> 00:13:50,870 who the leader is at any moment with 381 00:13:50,870 --> 00:13:52,470 the sheep in terms of the the leader 382 00:13:52,470 --> 00:13:53,930 of the movement, who takes 383 00:13:54,274 --> 00:13:56,355 this the flock in a particular direction or 384 00:13:56,355 --> 00:13:58,035 parts of the flock in a particular direction? 385 00:13:58,035 --> 00:14:00,295 Yeah. Sure. I mean, that that is something, 386 00:14:00,754 --> 00:14:03,075 that that is observed, and it's something that 387 00:14:03,075 --> 00:14:04,134 was looked at, 388 00:14:05,394 --> 00:14:07,139 in particular in one of the models that 389 00:14:07,139 --> 00:14:09,460 I discussed in the piece, work done by 390 00:14:09,460 --> 00:14:11,559 Fernando Peruana and colleagues, 391 00:14:12,019 --> 00:14:13,960 at one of the universities in Paris, 392 00:14:14,740 --> 00:14:17,620 where they they were watching. So they started 393 00:14:17,620 --> 00:14:20,019 off empirically. They were just watching small groups, 394 00:14:20,019 --> 00:14:23,044 sometimes really tiny groups of of sheep, you 395 00:14:23,044 --> 00:14:25,605 know, move around in a field grazing. And 396 00:14:25,605 --> 00:14:27,365 they found that there was this kind of 397 00:14:27,365 --> 00:14:27,865 tendency 398 00:14:28,804 --> 00:14:29,384 to occasionally 399 00:14:30,245 --> 00:14:32,404 develop to adopt to kind of, you know, 400 00:14:32,404 --> 00:14:34,404 moving mode where they all walk in some 401 00:14:34,404 --> 00:14:36,404 single file to a different part of the 402 00:14:36,404 --> 00:14:36,904 field. 403 00:14:37,730 --> 00:14:40,210 But what they observed was that there so 404 00:14:40,210 --> 00:14:41,429 there's a leader there, 405 00:14:41,970 --> 00:14:44,529 by Natesti if there's a line, but they 406 00:14:44,529 --> 00:14:46,850 they found that the sheep seem to take 407 00:14:46,850 --> 00:14:48,950 it in turns. So there's no, 408 00:14:49,649 --> 00:14:52,355 single leader who decides that in the flock 409 00:14:52,355 --> 00:14:53,095 each time. 410 00:14:53,475 --> 00:14:55,394 It seems to happen more or less at 411 00:14:55,394 --> 00:14:57,894 random. So pretty much each of the sheep 412 00:14:58,195 --> 00:14:59,095 gets a turn, 413 00:14:59,634 --> 00:15:00,934 at being the leader. 414 00:15:01,315 --> 00:15:03,394 And, again, you know, that sounds like that's 415 00:15:03,394 --> 00:15:04,774 all very kind of egalitarian 416 00:15:05,235 --> 00:15:07,620 and, you know, it's you could imagine the 417 00:15:07,620 --> 00:15:09,620 sheep saying, okay. Now it's my turn to 418 00:15:09,620 --> 00:15:11,700 be leader. But actually, you know, it seems 419 00:15:11,700 --> 00:15:13,220 like it doesn't happen or at least we 420 00:15:13,220 --> 00:15:15,059 don't need to assume that. If we simply 421 00:15:15,059 --> 00:15:15,559 assume 422 00:15:15,940 --> 00:15:17,079 that whoever, 423 00:15:18,579 --> 00:15:20,740 becomes the leader, that that is, you know, 424 00:15:20,740 --> 00:15:22,120 something that just happens 425 00:15:22,424 --> 00:15:24,684 randomly, that there is a particular chance 426 00:15:25,225 --> 00:15:28,184 at any moment that any individual will become 427 00:15:28,184 --> 00:15:30,184 the leader of one of those moving groups, 428 00:15:30,184 --> 00:15:31,325 that that's enough 429 00:15:31,705 --> 00:15:33,965 to account for for what we see. 430 00:15:34,759 --> 00:15:36,919 So, yeah, there there absolutely is. And the 431 00:15:37,080 --> 00:15:39,480 you you see the the advantage there's an 432 00:15:39,480 --> 00:15:42,200 advantage in in having that kind of, if 433 00:15:42,200 --> 00:15:43,980 you like, that kind of cheap algorithm, 434 00:15:44,360 --> 00:15:44,840 you know, 435 00:15:45,480 --> 00:15:47,340 inherent in in their behaviors, 436 00:15:48,404 --> 00:15:51,365 relative to their always being the same leader 437 00:15:51,365 --> 00:15:51,865 because, 438 00:15:52,725 --> 00:15:55,524 it means that there's more pooling of the 439 00:15:55,524 --> 00:15:56,024 information 440 00:15:56,485 --> 00:15:58,424 that all of the individuals have. 441 00:15:59,205 --> 00:16:00,965 So, you know, it may be that one 442 00:16:00,965 --> 00:16:02,664 of them knows or has has 443 00:16:02,965 --> 00:16:05,210 realized that one part of the field seems 444 00:16:05,210 --> 00:16:07,790 to be more attractive or less, you know, 445 00:16:08,169 --> 00:16:10,190 chewed on than another. And 446 00:16:11,210 --> 00:16:13,610 the ideal is that the flock has access 447 00:16:13,610 --> 00:16:15,629 to the information of all the individuals. 448 00:16:16,764 --> 00:16:18,605 You know, this is something that we might 449 00:16:18,605 --> 00:16:21,325 also see in in in flocking birds or 450 00:16:21,325 --> 00:16:23,245 in the other sort of flocking animals where 451 00:16:23,245 --> 00:16:24,764 it might be that 1 or 2 individuals 452 00:16:24,764 --> 00:16:27,165 spot a predator where the rest of the 453 00:16:27,165 --> 00:16:29,600 the group hasn't. And so you want to 454 00:16:29,600 --> 00:16:31,519 make use of that. You want to pool 455 00:16:31,519 --> 00:16:33,539 that information that everyone has. 456 00:16:33,919 --> 00:16:36,720 So this idea with sheep, this idea of 457 00:16:36,720 --> 00:16:39,679 constantly changing the the leader in these sort 458 00:16:39,679 --> 00:16:41,539 of episodes of walking, 459 00:16:44,325 --> 00:16:46,485 It's it's an it's an efficient way of 460 00:16:46,485 --> 00:16:46,985 working, 461 00:16:47,524 --> 00:16:49,784 in the sense that it's efficient in information 462 00:16:49,845 --> 00:16:52,644 sharing. I I can't help wondering if it's 463 00:16:52,644 --> 00:16:54,884 not that, efficient if you're trying to run 464 00:16:54,884 --> 00:16:56,565 a political party or a government to keep 465 00:16:56,565 --> 00:16:57,544 changing your computer. 466 00:16:59,199 --> 00:17:01,399 Well, you know, I mean, even there, that's 467 00:17:01,600 --> 00:17:04,160 although that's true, you know, there is a 468 00:17:04,160 --> 00:17:06,559 discussion about whether there are more sort of 469 00:17:06,559 --> 00:17:08,579 egalitarian, you know, whether it would be 470 00:17:08,880 --> 00:17:11,440 more sensible, for example, instead of having a 471 00:17:11,440 --> 00:17:14,275 House of Lords to have, you know, people 472 00:17:14,414 --> 00:17:14,914 randomly, 473 00:17:16,575 --> 00:17:18,515 you know, chosen from the population 474 00:17:18,974 --> 00:17:21,134 to lead a body like that and that 475 00:17:21,134 --> 00:17:23,855 there's a constant turnover there. And maybe that 476 00:17:23,855 --> 00:17:25,694 would be more efficient in terms of being 477 00:17:25,694 --> 00:17:28,029 able to make better use of the information 478 00:17:28,029 --> 00:17:30,349 that everyone has rather than that a few 479 00:17:30,349 --> 00:17:33,549 privileged individuals have for life. But wouldn't the 480 00:17:33,549 --> 00:17:35,710 concern there be that you could get someone 481 00:17:35,710 --> 00:17:37,950 that was sort of, you know, a a 482 00:17:37,950 --> 00:17:39,410 conspiracy theorist running 483 00:17:39,974 --> 00:17:42,055 an important part of the world. I mean, 484 00:17:42,055 --> 00:17:44,775 absolutely. You know, questions like that, they're they're 485 00:17:44,775 --> 00:17:47,575 they're complex ones, but I suppose the the 486 00:17:47,575 --> 00:17:49,734 the principle there is, you know, you could 487 00:17:49,734 --> 00:17:51,734 equally get them and you could equally get 488 00:17:51,734 --> 00:17:53,174 that in the house. And when you do 489 00:17:53,174 --> 00:17:54,750 get that in the house of lords now, 490 00:17:54,829 --> 00:17:56,210 and they're there for life. 491 00:17:57,150 --> 00:17:58,910 So, you know, as long as you have 492 00:17:58,910 --> 00:18:00,690 that constant sort of turnover, 493 00:18:01,630 --> 00:18:03,630 the the the idea would be that, you 494 00:18:03,630 --> 00:18:05,730 know, on average, you're going to, 495 00:18:06,190 --> 00:18:08,430 get a better sort of representation and a 496 00:18:08,430 --> 00:18:09,410 fairer representation 497 00:18:09,934 --> 00:18:11,694 of all the information and all the views 498 00:18:11,694 --> 00:18:14,174 in the population. There's that kind of angle 499 00:18:14,174 --> 00:18:16,115 to it, but I wonder, is this actually 500 00:18:16,174 --> 00:18:18,734 useful for the farmer who's herding the sheep 501 00:18:18,734 --> 00:18:20,255 out there? Well, I I think I mean, 502 00:18:20,255 --> 00:18:22,194 first of all, I guess the question is, 503 00:18:22,390 --> 00:18:25,269 can a model like this even reproduce what 504 00:18:25,269 --> 00:18:27,829 we see in terms of herding? And, you 505 00:18:27,829 --> 00:18:30,169 know, that's the thing I found quite remarkable 506 00:18:30,230 --> 00:18:31,130 that it can. 507 00:18:31,509 --> 00:18:33,130 That without any 508 00:18:33,990 --> 00:18:36,410 assumptions and here I'm talking about a model, 509 00:18:36,789 --> 00:18:38,294 that's being developed by, 510 00:18:38,855 --> 00:18:40,474 peep researchers at Harvard, 511 00:18:41,014 --> 00:18:43,434 and others to try to look at shepherding 512 00:18:43,494 --> 00:18:45,894 behavior. And, you know, here, as as I 513 00:18:45,894 --> 00:18:47,974 said initially, it just seems like, how on 514 00:18:47,974 --> 00:18:49,894 earth do you make a physics based model 515 00:18:49,894 --> 00:18:52,134 of a sheepdog actually trying to herd, you 516 00:18:52,134 --> 00:18:53,359 know, a 517 00:18:53,740 --> 00:18:55,819 flock of sheep. But it seems that you 518 00:18:55,819 --> 00:18:58,220 can, that it's an optimization problem is how 519 00:18:58,220 --> 00:19:00,059 they present it. So you're you know, the 520 00:19:00,059 --> 00:19:02,460 the the challenge is to try to get 521 00:19:02,460 --> 00:19:03,200 the flock 522 00:19:03,660 --> 00:19:06,835 from a to b as quickly as possible 523 00:19:06,894 --> 00:19:09,234 without losing any sheep on the way. 524 00:19:09,615 --> 00:19:10,115 So 525 00:19:10,494 --> 00:19:13,055 what what is the optimum strategy for a 526 00:19:13,055 --> 00:19:14,914 dog to, to undertake 527 00:19:15,455 --> 00:19:16,994 to encourage that motion? 528 00:19:17,295 --> 00:19:19,934 Assuming that there's this repulsion between the dog 529 00:19:19,934 --> 00:19:22,279 and the sheep so that that's what's going 530 00:19:22,279 --> 00:19:24,279 to kind of move the the flock along. 531 00:19:24,279 --> 00:19:26,140 And there's there's this attraction 532 00:19:26,519 --> 00:19:28,359 between the sheep themselves and that's what's going 533 00:19:28,359 --> 00:19:30,460 to get to keep the flock coherent. So 534 00:19:30,519 --> 00:19:32,680 given those constraints, you know, what's the most 535 00:19:32,680 --> 00:19:34,599 efficient way of doing it? And they come 536 00:19:34,599 --> 00:19:36,214 up with three possibilities 537 00:19:36,674 --> 00:19:37,734 that do the job. 538 00:19:38,434 --> 00:19:40,115 One is that the dog just sort of 539 00:19:40,115 --> 00:19:42,214 runs from side to side of the flock, 540 00:19:42,275 --> 00:19:44,775 keeping it, you know, in order but gradually 541 00:19:44,994 --> 00:19:46,994 kind of getting it to move, in a 542 00:19:46,994 --> 00:19:47,815 single direction. 543 00:19:48,299 --> 00:19:50,779 Another is that the dog runs in circles 544 00:19:50,779 --> 00:19:52,720 around the flock, but they're kind of corkscrewing 545 00:19:52,860 --> 00:19:55,200 circles so that it's gradually getting somewhere. 546 00:19:55,660 --> 00:19:58,059 Both of those strategies are ones that are 547 00:19:58,059 --> 00:20:00,000 seen, literally in the field. 548 00:20:00,634 --> 00:20:03,214 And then there's a third strategy, which isn't 549 00:20:03,274 --> 00:20:05,434 seen as far as the researchers are aware, 550 00:20:05,434 --> 00:20:07,274 which is that the dog actually it almost 551 00:20:07,274 --> 00:20:09,134 kind of burrows into the flock. 552 00:20:10,154 --> 00:20:12,634 But, because the flock is coherent, it doesn't 553 00:20:12,634 --> 00:20:15,079 just scatter. It sort of stays together, but, 554 00:20:15,220 --> 00:20:17,779 you know, it it sort of draws back 555 00:20:17,779 --> 00:20:19,700 from the dog within it. And so by 556 00:20:19,700 --> 00:20:21,859 the by the dog moving, the flock, it 557 00:20:21,859 --> 00:20:23,380 kind of moves with it as if the 558 00:20:23,380 --> 00:20:26,039 dog is like a driver in a car, 559 00:20:26,099 --> 00:20:28,724 and so they call this strategy driving. So 560 00:20:28,724 --> 00:20:30,484 it seems to be one way that the 561 00:20:30,484 --> 00:20:32,884 the sheepdog could work, but but doesn't. And 562 00:20:32,884 --> 00:20:33,944 it may be that 563 00:20:34,244 --> 00:20:36,964 the the flocks just aren't really sort of 564 00:20:36,964 --> 00:20:39,365 cohesive enough to make that a viable strategy. 565 00:20:39,365 --> 00:20:40,984 We we, you know, we don't know. 566 00:20:41,285 --> 00:20:43,144 But, you know, it does seem to capture 567 00:20:43,669 --> 00:20:46,789 what actual sheepdog do. And so, you know, 568 00:20:46,789 --> 00:20:48,549 that's a kind of it seems like that's 569 00:20:48,549 --> 00:20:50,630 a kind of validation of the model itself. 570 00:20:50,630 --> 00:20:52,470 And so if you've got something like that 571 00:20:52,470 --> 00:20:54,710 that works, then you can start to think, 572 00:20:54,710 --> 00:20:56,710 okay. What are there ways that, 573 00:20:57,190 --> 00:20:58,569 you know, are there better ways 574 00:20:58,954 --> 00:21:00,474 of of of doing this or are there 575 00:21:00,474 --> 00:21:02,875 ways that we could improve the efficiency with 576 00:21:02,875 --> 00:21:05,615 which the the dogs work? Or in particular, 577 00:21:06,634 --> 00:21:09,195 are there ways that we might automate this 578 00:21:09,195 --> 00:21:12,474 process using, for example, drones or using, you 579 00:21:12,474 --> 00:21:13,295 know, robotic, 580 00:21:14,769 --> 00:21:17,490 you know, entities to to do the herding 581 00:21:17,490 --> 00:21:17,990 instead. 582 00:21:18,289 --> 00:21:19,650 And I, you know, I I loved it 583 00:21:19,650 --> 00:21:19,970 that, 584 00:21:20,609 --> 00:21:22,609 what some of the researchers involved in this 585 00:21:22,609 --> 00:21:24,369 work said, well, if you if you speak 586 00:21:24,369 --> 00:21:27,009 to farmers about that possibility of using drones 587 00:21:27,009 --> 00:21:28,275 or whatever, they just laugh, 588 00:21:29,315 --> 00:21:32,115 because, you know, the technology just isn't ready. 589 00:21:32,115 --> 00:21:33,095 But in particular, 590 00:21:33,474 --> 00:21:35,714 it seems that sheepdog you know, sheepdog are 591 00:21:35,714 --> 00:21:36,775 really smart dogs. 592 00:21:37,315 --> 00:21:38,994 That's why they hear that they're they're so 593 00:21:38,994 --> 00:21:40,295 good at doing this job. 594 00:21:41,309 --> 00:21:43,490 So they have a kind of an instinct 595 00:21:43,549 --> 00:21:44,289 it seems 596 00:21:44,589 --> 00:21:47,250 to be able to respond on the fly 597 00:21:47,549 --> 00:21:49,069 to what the sheep are doing. If you've 598 00:21:49,069 --> 00:21:50,669 got one that wanders off, you know, the 599 00:21:50,669 --> 00:21:53,714 sheepdog can respond to it in ways that 600 00:21:54,034 --> 00:21:56,355 it's probably gonna be very hard to program 601 00:21:56,355 --> 00:21:57,894 into robots or drones. 602 00:21:58,355 --> 00:22:00,115 But, you know, if you're ever going to 603 00:22:00,115 --> 00:22:03,494 do that, then models like this are precisely 604 00:22:03,634 --> 00:22:05,234 the kind of thing you'd need to figure 605 00:22:05,234 --> 00:22:07,494 out what are the basic rules of behavior 606 00:22:07,950 --> 00:22:09,809 that a an automated 607 00:22:10,589 --> 00:22:11,809 shepherd or sheepdog, 608 00:22:12,589 --> 00:22:14,509 would have to follow in order to do 609 00:22:14,509 --> 00:22:17,390 the job efficiently and reliably. I can't help 610 00:22:17,390 --> 00:22:19,069 but wonder why on earth you'd want to 611 00:22:19,069 --> 00:22:21,595 replace sheepdogs, though. I mean, what would be 612 00:22:21,595 --> 00:22:23,275 the reason? Yeah. Well, they require a lot 613 00:22:23,275 --> 00:22:23,934 of training, 614 00:22:24,554 --> 00:22:27,275 and, you know, they if if and they 615 00:22:27,275 --> 00:22:28,255 have their limitations. 616 00:22:28,634 --> 00:22:30,154 They can only go at a certain you 617 00:22:30,154 --> 00:22:31,855 know, they can't go too fast. 618 00:22:34,230 --> 00:22:35,130 And, you know, 619 00:22:35,910 --> 00:22:37,609 it it could be that particularly 620 00:22:37,910 --> 00:22:38,490 if you're 621 00:22:38,789 --> 00:22:40,410 working with bigger flocks 622 00:22:40,789 --> 00:22:43,910 that, you know, sheepdogs would a single sheepdog 623 00:22:43,910 --> 00:22:46,170 would struggle to, to to contain, 624 00:22:46,505 --> 00:22:48,265 you know, might it be then that you'd 625 00:22:48,265 --> 00:22:50,845 have to use something more systematic, 626 00:22:51,945 --> 00:22:54,684 and with great a greater range of capabilities 627 00:22:55,065 --> 00:22:56,605 in order to do the job. 628 00:22:56,985 --> 00:22:59,005 So, you know, I suppose you could imagine 629 00:22:59,065 --> 00:23:00,869 situations where where that's, 630 00:23:01,910 --> 00:23:03,289 where where that's the case. 631 00:23:03,990 --> 00:23:07,029 You know, drones never tire, drones never need 632 00:23:07,029 --> 00:23:07,529 feeding. 633 00:23:08,869 --> 00:23:11,029 But, I mean, you know, I I suspect 634 00:23:11,029 --> 00:23:13,690 that behind your question is the same feeling 635 00:23:13,750 --> 00:23:16,309 for me that actually it's amazing and lovely 636 00:23:16,309 --> 00:23:18,654 that sheepdog are able to do this. And, 637 00:23:18,654 --> 00:23:20,335 you know, what a shame it would be 638 00:23:20,335 --> 00:23:22,835 if they were replaced by something automatic. 639 00:23:23,214 --> 00:23:24,674 I know. I think the only 640 00:23:24,974 --> 00:23:26,894 possible reason I can think for it is 641 00:23:26,894 --> 00:23:29,294 if you had a sort of robotic dog 642 00:23:29,294 --> 00:23:30,115 that had 643 00:23:30,690 --> 00:23:32,929 some form of artificial intelligence, and it worked 644 00:23:32,929 --> 00:23:33,669 with the sheep 645 00:23:34,130 --> 00:23:36,529 so much that eventually you could ask it 646 00:23:36,529 --> 00:23:38,869 whether androids dream of electric sheep. 647 00:23:39,730 --> 00:23:42,049 Brilliant. Of course, you would need to get 648 00:23:42,049 --> 00:23:43,894 that in there. I guess, you know, I 649 00:23:43,894 --> 00:23:45,494 I mean, I I think the other, 650 00:23:45,894 --> 00:23:47,654 answer to that might be, well, you know, 651 00:23:47,654 --> 00:23:49,095 it may be that you don't wanna do 652 00:23:49,095 --> 00:23:50,855 this with sheep, but it may be that 653 00:23:50,855 --> 00:23:53,194 you wanna do it with other systems, including 654 00:23:53,414 --> 00:23:53,914 maybe, 655 00:23:55,109 --> 00:23:57,990 you know, sort of nanoscopic inorganic systems where 656 00:23:57,990 --> 00:23:58,970 you've got a load 657 00:23:59,349 --> 00:24:02,009 of what are are called active active particles 658 00:24:02,069 --> 00:24:03,750 that can move under their own steam, and 659 00:24:03,750 --> 00:24:05,910 you want to get them somewhere and you 660 00:24:05,910 --> 00:24:08,774 want some other, you know, active particle or 661 00:24:08,774 --> 00:24:11,174 nanorobot or something to, you know, be able 662 00:24:11,174 --> 00:24:13,894 to move them or other animal systems or 663 00:24:13,894 --> 00:24:16,054 possibly even cells. You know, if you want 664 00:24:16,054 --> 00:24:18,694 to marshal cells in a particular direction, can 665 00:24:18,694 --> 00:24:20,794 you do that with some kind of artificial 666 00:24:20,934 --> 00:24:23,220 entity that is programmed in certain way? 667 00:24:23,700 --> 00:24:24,919 So, you know, these 668 00:24:25,380 --> 00:24:28,339 these, questions of how to shepherd a load 669 00:24:28,339 --> 00:24:28,839 of, 670 00:24:29,220 --> 00:24:30,200 you know, moving 671 00:24:30,579 --> 00:24:32,679 possibly quite idiosyncratic particles, 672 00:24:33,140 --> 00:24:34,599 there's a broader applicability 673 00:24:34,980 --> 00:24:37,115 to it than just she. Can we apply 674 00:24:37,115 --> 00:24:39,595 this to to people? Can we is there 675 00:24:39,595 --> 00:24:42,315 some way we can help with crowding at, 676 00:24:42,315 --> 00:24:44,634 I don't know, concerts or football matches or 677 00:24:44,634 --> 00:24:46,714 something by looking at this? It's it's already 678 00:24:46,714 --> 00:24:49,035 being done. Models like this to try to 679 00:24:49,035 --> 00:24:50,494 understand crowd behavior 680 00:24:51,089 --> 00:24:53,890 have been used to try to plan things 681 00:24:53,890 --> 00:24:56,069 like events like Notting Hill Carnival 682 00:24:56,450 --> 00:24:58,450 where you can, you know, literally map out 683 00:24:58,450 --> 00:25:00,929 the real route that the carnival takes and, 684 00:25:00,929 --> 00:25:02,609 you know, get some sense of what the 685 00:25:02,609 --> 00:25:05,275 crowd motions might be like, where you might 686 00:25:05,275 --> 00:25:07,595 have pressure points and, you know, difficulties that 687 00:25:07,595 --> 00:25:10,234 might need extra policing or extra guidance or 688 00:25:10,234 --> 00:25:10,894 so on. 689 00:25:11,275 --> 00:25:12,575 It's also been 690 00:25:13,115 --> 00:25:15,355 applied models like this have been applied to 691 00:25:15,355 --> 00:25:15,855 the, 692 00:25:17,115 --> 00:25:19,535 the Muslim pilgrimage of the the Hajj, 693 00:25:20,609 --> 00:25:21,509 which has 694 00:25:23,330 --> 00:25:24,150 had problems, 695 00:25:24,769 --> 00:25:27,009 you know, some years because so many people 696 00:25:27,009 --> 00:25:29,490 come to it. It's this massive crowd event 697 00:25:29,490 --> 00:25:31,330 that has, you know, the real danger of 698 00:25:31,330 --> 00:25:33,330 there being sort of buildups of pressure in 699 00:25:33,330 --> 00:25:35,095 the crowd. And there have been, 700 00:25:35,494 --> 00:25:37,575 disasters really that have happened in the past 701 00:25:37,575 --> 00:25:39,654 because of this. And so this sort of 702 00:25:39,654 --> 00:25:42,615 modeling has been applied also to to events 703 00:25:42,615 --> 00:25:44,714 like that to see if you can create 704 00:25:44,934 --> 00:25:46,394 better safety measures. 705 00:25:47,480 --> 00:25:49,799 And just sort of crowd panic in general, 706 00:25:49,799 --> 00:25:52,539 you know, is is a really difficult problem, 707 00:25:53,159 --> 00:25:53,659 that, 708 00:25:55,319 --> 00:25:55,980 you know, 709 00:25:56,440 --> 00:25:59,259 models like this can can can inform 710 00:25:59,559 --> 00:26:00,134 at least. 711 00:26:00,535 --> 00:26:03,195 So, you know, it's not necessarily that you'd, 712 00:26:04,134 --> 00:26:05,734 you'd be thinking of a a sort of 713 00:26:05,734 --> 00:26:07,994 shepherding problem, but that you'd be anticipating 714 00:26:09,174 --> 00:26:11,575 problems that might arise in these sort of 715 00:26:11,575 --> 00:26:12,795 mass crowd movements 716 00:26:13,335 --> 00:26:16,669 that are possibly quite predictable ones just as 717 00:26:16,669 --> 00:26:18,990 they are for road traffic, and then think 718 00:26:18,990 --> 00:26:20,990 about the kind of safety measures that might 719 00:26:20,990 --> 00:26:23,470 alleviate that. You mentioned your book that you 720 00:26:23,470 --> 00:26:25,309 wrote a a few years ago, but haven't 721 00:26:25,309 --> 00:26:26,509 you got a new one that's sort of 722 00:26:26,509 --> 00:26:28,704 looking in this area? Oh, yeah. How life 723 00:26:28,704 --> 00:26:31,024 works. That's looking more at the kind of 724 00:26:31,024 --> 00:26:34,784 molecular details of, of of that question. But 725 00:26:34,784 --> 00:26:36,544 it does, you know, it it it does 726 00:26:36,544 --> 00:26:39,044 then sort of, open out into 727 00:26:39,424 --> 00:26:41,684 looking at higher levels of the system. 728 00:26:42,410 --> 00:26:43,470 So it's actually 729 00:26:44,009 --> 00:26:45,889 yeah. I mean, in the sense that the 730 00:26:46,089 --> 00:26:47,710 that book is looking at 731 00:26:48,250 --> 00:26:51,130 questions of emergence in biological systems, you know, 732 00:26:51,130 --> 00:26:53,130 that's what we're talking about. It's absolutely what 733 00:26:53,130 --> 00:26:55,929 we're talking about with these collective motions of 734 00:26:55,929 --> 00:26:58,054 animals. I mean, you know, the murmurations 735 00:26:58,434 --> 00:27:00,694 of of birds are one of the classic 736 00:27:00,755 --> 00:27:04,194 examples of of emergence but we absolutely see 737 00:27:04,194 --> 00:27:06,835 in biological systems in in all sorts of 738 00:27:06,835 --> 00:27:09,474 ways how you get these higher levels of 739 00:27:09,474 --> 00:27:09,974 organization 740 00:27:10,869 --> 00:27:11,609 that are 741 00:27:12,069 --> 00:27:14,329 somehow somehow seem to be autonomous 742 00:27:15,029 --> 00:27:18,390 from the really lower level details of what 743 00:27:18,390 --> 00:27:20,549 individual molecules are doing and what genes are 744 00:27:20,549 --> 00:27:23,690 switched on. So that broader question 745 00:27:24,224 --> 00:27:25,525 of how you get 746 00:27:25,984 --> 00:27:28,724 emergent sort of coherence and robustness 747 00:27:29,105 --> 00:27:30,404 in the face of 748 00:27:31,265 --> 00:27:31,765 microscopic 749 00:27:32,144 --> 00:27:32,644 details 750 00:27:33,025 --> 00:27:35,025 that might be quite sort of random and 751 00:27:35,025 --> 00:27:35,525 idiosyncratic. 752 00:27:36,839 --> 00:27:39,259 That's absolutely the same kind of question, 753 00:27:40,119 --> 00:27:42,200 that we we see in, you know, in 754 00:27:42,200 --> 00:27:44,759 these cases. And in fact, it's actually you 755 00:27:44,759 --> 00:27:46,460 could say the same kind of problem 756 00:27:46,759 --> 00:27:48,299 that, you know, in a sense, 757 00:27:49,335 --> 00:27:52,775 that emergence in biology continues beyond the level 758 00:27:52,775 --> 00:27:54,634 of the organism to the ecosystem 759 00:27:54,934 --> 00:27:56,555 and for us to the society. 760 00:27:57,575 --> 00:27:58,075 And 761 00:27:58,375 --> 00:28:00,315 there are similar kind of principles 762 00:28:01,009 --> 00:28:03,409 involved in the sense of how do you 763 00:28:03,409 --> 00:28:05,109 get a high level system 764 00:28:05,569 --> 00:28:07,589 that is reliable and robust 765 00:28:08,049 --> 00:28:09,970 and isn't going to break down as soon 766 00:28:09,970 --> 00:28:11,349 as something microscopic 767 00:28:11,809 --> 00:28:12,629 goes awry. 768 00:28:13,715 --> 00:28:15,394 A walk among the sheep. They they don't 769 00:28:15,394 --> 00:28:17,075 worry about me walking amongst them. They just 770 00:28:17,075 --> 00:28:19,555 stay where they are. But it the movements 771 00:28:19,555 --> 00:28:21,555 that they have, as you say, you know, 772 00:28:21,555 --> 00:28:23,335 sort of that bit of field looks 773 00:28:23,715 --> 00:28:25,494 tastier or whatever it is, 774 00:28:25,799 --> 00:28:28,120 It it it doesn't seem to make sense. 775 00:28:28,120 --> 00:28:29,500 It seems to be 776 00:28:29,799 --> 00:28:30,940 just sort of 777 00:28:31,240 --> 00:28:33,480 I'm going to move now. It doesn't seem 778 00:28:33,480 --> 00:28:35,480 to be any more to it than that. 779 00:28:35,480 --> 00:28:38,200 Right? It just seems like, yeah. I'm moving 780 00:28:38,200 --> 00:28:39,720 moving over there and then the others follow 781 00:28:39,720 --> 00:28:42,595 because they, oh, maybe they found something. It 782 00:28:42,595 --> 00:28:45,174 doesn't seem to be kind of, you know, 783 00:28:45,394 --> 00:28:46,295 in any way, 784 00:28:47,634 --> 00:28:49,335 decisive based on evidence 785 00:28:49,795 --> 00:28:52,134 about just sort of going somewhere. The information 786 00:28:52,275 --> 00:28:54,179 bit of it, that's really lovely. Right? That 787 00:28:54,179 --> 00:28:56,259 that they're sharing that information, but maybe the 788 00:28:56,259 --> 00:28:58,279 information is dodgy. It isn't better. 789 00:28:58,899 --> 00:29:00,740 Mhmm. Well, I mean, okay. So maybe the 790 00:29:00,740 --> 00:29:02,500 first thing to say about that is that, 791 00:29:03,139 --> 00:29:05,059 and this is something that I heard in 792 00:29:05,059 --> 00:29:08,255 in writing this article that, you know, farmers, 793 00:29:08,955 --> 00:29:11,055 will say, actually, sheep, 794 00:29:11,595 --> 00:29:14,015 they're more intelligent than you think they are. 795 00:29:14,955 --> 00:29:16,575 They're and they're more individual 796 00:29:17,115 --> 00:29:19,615 than you think they are. So for example, 797 00:29:20,075 --> 00:29:21,455 it seems that sometimes, 798 00:29:23,359 --> 00:29:24,339 sheep flocks 799 00:29:24,960 --> 00:29:25,460 respond 800 00:29:25,919 --> 00:29:26,419 to 801 00:29:26,960 --> 00:29:29,839 what the farmer has told the sheepdog to 802 00:29:29,839 --> 00:29:31,519 do. So the farmer can, you know, has 803 00:29:31,519 --> 00:29:34,000 whistles or whatever to instruct the sheepdog to 804 00:29:34,000 --> 00:29:36,799 do particular things. The sheep get to to 805 00:29:36,799 --> 00:29:37,299 recognize 806 00:29:38,105 --> 00:29:38,765 those calls 807 00:29:39,144 --> 00:29:41,705 and start behaving, you know, as the dog 808 00:29:41,705 --> 00:29:43,465 would want them to behave before the dog 809 00:29:43,465 --> 00:29:45,305 has really done anything, you know. So then 810 00:29:45,305 --> 00:29:46,984 they are picking up on these things. But 811 00:29:46,984 --> 00:29:48,664 also it seems like there's quite a lot 812 00:29:48,664 --> 00:29:49,244 of variability 813 00:29:49,705 --> 00:29:52,109 in the way they behave. Some sheep just 814 00:29:52,109 --> 00:29:54,109 look at the sheepdog and think whatever and 815 00:29:54,109 --> 00:29:56,109 ignore it. Whereas others think, oh my god, 816 00:29:56,109 --> 00:29:57,789 and run like mad the moment they see 817 00:29:57,789 --> 00:30:00,769 it. So that, you know, that's, that variability 818 00:30:01,150 --> 00:30:02,369 you need to build into, 819 00:30:02,910 --> 00:30:05,730 the into into these models. But it also 820 00:30:06,575 --> 00:30:09,214 undermines the the, you know, the the kind 821 00:30:09,214 --> 00:30:11,615 of meme like stereotype really is, you know, 822 00:30:11,615 --> 00:30:13,535 sheep are just they just all do the 823 00:30:13,535 --> 00:30:15,075 same thing. Well, they really don't. 824 00:30:15,934 --> 00:30:17,775 But the question of, you know, why they're 825 00:30:17,775 --> 00:30:19,695 doing this in the first place, it's it's 826 00:30:19,695 --> 00:30:21,234 it's all about foraging 827 00:30:21,599 --> 00:30:24,559 strategies, and each animal has, you know, has 828 00:30:24,559 --> 00:30:25,460 some. And 829 00:30:26,240 --> 00:30:28,640 the this has been, a very sort of 830 00:30:28,640 --> 00:30:31,380 rich area of research of how do animals 831 00:30:31,519 --> 00:30:34,660 decide what strategy to follow, what's what's efficient. 832 00:30:35,039 --> 00:30:36,579 Some of them seem to, 833 00:30:37,184 --> 00:30:39,825 undergo what are called levy flights where, you 834 00:30:39,825 --> 00:30:42,464 know, the idea is you go to one 835 00:30:42,464 --> 00:30:44,625 location and you forage around a little bit 836 00:30:44,625 --> 00:30:46,384 around there with random walk, and then you 837 00:30:46,384 --> 00:30:48,065 make a big jump to somewhere else and 838 00:30:48,065 --> 00:30:49,980 then you forage a little bit around there. 839 00:30:50,460 --> 00:30:52,539 That's something that you could describe using a 840 00:30:52,539 --> 00:30:54,480 particular kind of statistics. 841 00:30:55,339 --> 00:30:57,259 You know, other animal foragers. I mean, if 842 00:30:57,259 --> 00:30:59,660 we think the classic example really is bees. 843 00:30:59,660 --> 00:31:02,380 You know, that's that's extraordinary, the amount of 844 00:31:02,380 --> 00:31:05,875 cognition that's involved there that they will you 845 00:31:05,875 --> 00:31:06,934 know, they'll go out, 846 00:31:07,394 --> 00:31:09,315 they'll, you know, they'll find some, 847 00:31:10,355 --> 00:31:11,894 some sort of source of food, 848 00:31:12,195 --> 00:31:13,795 come back to the hive, and tell the 849 00:31:13,795 --> 00:31:16,115 others where it is but with this incredible 850 00:31:16,115 --> 00:31:18,355 waggle dance and the others will understand and 851 00:31:18,355 --> 00:31:20,919 off they'll go. And sometimes they won't. Sometimes 852 00:31:20,919 --> 00:31:22,440 they'll think, you know what? I'm it doesn't 853 00:31:22,599 --> 00:31:24,119 I you know, I've been there and it's 854 00:31:24,119 --> 00:31:25,720 not I mean, I'm you know, this isn't 855 00:31:25,720 --> 00:31:27,480 what the bees are thinking, but it's how 856 00:31:27,480 --> 00:31:30,039 they seem to behave. They don't all just 857 00:31:30,039 --> 00:31:32,595 sort of respond in this programmed way. So 858 00:31:32,595 --> 00:31:34,194 even in the case of a bee with 859 00:31:34,194 --> 00:31:36,275 this kind of, you know, brain the size 860 00:31:36,275 --> 00:31:37,654 of a grain of salt, 861 00:31:38,035 --> 00:31:40,994 let alone a sheep, there's an amazing amount 862 00:31:40,994 --> 00:31:44,054 of cognition, of subtle cognition going on there. 863 00:31:44,275 --> 00:31:44,775 So, 864 00:31:45,234 --> 00:31:46,775 you know, I I I think 865 00:31:47,230 --> 00:31:47,730 although, 866 00:31:48,349 --> 00:31:50,109 I mean in a way that's what these 867 00:31:50,109 --> 00:31:52,589 models are kind of showing us that, you 868 00:31:52,589 --> 00:31:55,970 know, we can be described using these particle 869 00:31:56,029 --> 00:31:58,130 based models in certain situations 870 00:31:58,750 --> 00:32:00,509 and yet we like to think that we 871 00:32:00,509 --> 00:32:02,964 have this extraordinary amount of cognition that, you 872 00:32:02,964 --> 00:32:04,964 know, we're making use of in other contexts. 873 00:32:04,964 --> 00:32:07,065 And so we should probably not underestimate 874 00:32:07,764 --> 00:32:10,565 the amount of cognition that other animals are 875 00:32:10,565 --> 00:32:11,544 capable of, 876 00:32:12,565 --> 00:32:14,825 and the the way that the, 877 00:32:15,444 --> 00:32:17,304 the the way that that is 878 00:32:18,000 --> 00:32:19,220 harvested collectively. 879 00:32:20,000 --> 00:32:21,680 You know, that's the key thing that the 880 00:32:22,000 --> 00:32:23,779 these creatures aren't making decisions 881 00:32:24,400 --> 00:32:25,539 just by themselves. 882 00:32:26,000 --> 00:32:28,640 They're actually that that these strategies have this 883 00:32:28,640 --> 00:32:30,339 sort of collective ability 884 00:32:31,195 --> 00:32:33,535 to pool information and to make effective 885 00:32:33,835 --> 00:32:35,055 use of the group. 886 00:32:35,674 --> 00:32:36,174 So 887 00:32:36,875 --> 00:32:38,815 it's it's a much richer 888 00:32:39,355 --> 00:32:39,855 environment 889 00:32:40,475 --> 00:32:42,414 than you might think understandably 890 00:32:42,795 --> 00:32:44,634 by going up to a sheep and thinking, 891 00:32:44,634 --> 00:32:46,440 there's not a lot going on in there. 892 00:32:46,519 --> 00:32:49,079 Actually, you know, there may or there may 893 00:32:49,079 --> 00:32:50,759 not be, but what comes out of it 894 00:32:50,759 --> 00:32:52,059 is really quite rich. 895 00:32:53,240 --> 00:32:56,460 With no offense to any sheep or farmers 896 00:32:56,519 --> 00:32:57,019 listening, 897 00:32:57,319 --> 00:32:59,099 I wanted to know more about 898 00:32:59,575 --> 00:33:01,755 the human interaction in crowds. 899 00:33:03,174 --> 00:33:05,434 Someone who won the Ignat Nobel Prize 900 00:33:05,735 --> 00:33:06,634 for the research 901 00:33:07,095 --> 00:33:08,555 into crowd movement 902 00:33:09,095 --> 00:33:09,994 is Alessandro 903 00:33:10,535 --> 00:33:11,035 Corveto. 904 00:33:13,609 --> 00:33:15,690 I am an assistant professor at the Endoben 905 00:33:15,690 --> 00:33:16,670 University of Technology 906 00:33:17,369 --> 00:33:19,630 in the department of applied physics. 907 00:33:20,410 --> 00:33:22,170 I have here my own group that is 908 00:33:22,170 --> 00:33:24,830 called the AI for complex flows and traffic. 909 00:33:25,289 --> 00:33:28,029 And, what we do here is, 910 00:33:28,345 --> 00:33:30,684 well, essentially 2 things. So first, 911 00:33:31,305 --> 00:33:31,805 use 912 00:33:32,105 --> 00:33:32,605 tools 913 00:33:32,985 --> 00:33:34,605 of physics to explore, 914 00:33:34,985 --> 00:33:38,605 let's say, new physical systems, specifically traffic and, 915 00:33:39,225 --> 00:33:40,045 most importantly, 916 00:33:40,664 --> 00:33:43,485 crowd traffic. And the second thing is 917 00:33:44,000 --> 00:33:44,820 we use AI 918 00:33:45,200 --> 00:33:47,840 tools to try to crack problems in in 919 00:33:47,840 --> 00:33:50,820 complex fluids and complex flows that were that 920 00:33:51,840 --> 00:33:52,980 are open for long. 921 00:33:53,440 --> 00:33:56,500 And, and therefore AI is giving new opportunities 922 00:33:56,559 --> 00:33:57,380 in this direction. 923 00:33:57,784 --> 00:33:59,085 We won the 2021, 924 00:33:59,784 --> 00:34:03,085 Iqnoebel Prize for a research that we started 925 00:34:03,304 --> 00:34:04,684 somewhere around 2013 926 00:34:05,625 --> 00:34:07,944 and, that is, that is a very big 927 00:34:07,944 --> 00:34:09,065 part of my work, 928 00:34:09,864 --> 00:34:10,844 today as well. 929 00:34:11,385 --> 00:34:12,364 So we 930 00:34:12,869 --> 00:34:13,849 try to understand, 931 00:34:15,509 --> 00:34:19,049 whether we can establish some basic physical understanding 932 00:34:19,109 --> 00:34:19,609 of 933 00:34:20,309 --> 00:34:23,130 of the way pedestrian crowds moves. Okay? 934 00:34:23,829 --> 00:34:24,329 And 935 00:34:24,934 --> 00:34:26,795 and this means try to establish 936 00:34:27,414 --> 00:34:30,954 a physical model that reproduce, that explain, 937 00:34:31,414 --> 00:34:33,514 what we see as we look at crowds. 938 00:34:34,855 --> 00:34:35,355 And 939 00:34:36,454 --> 00:34:38,309 let's say crowds are 940 00:34:38,869 --> 00:34:40,869 very, let's say, as you can as you 941 00:34:40,869 --> 00:34:43,210 can imagine, a very random, a very stochastic 942 00:34:43,269 --> 00:34:45,750 system. Right? So imagine that you are yourself 943 00:34:45,750 --> 00:34:47,050 in a in a train station. 944 00:34:47,430 --> 00:34:49,349 What you do today is different from what 945 00:34:49,349 --> 00:34:51,764 you'll do tomorrow, and what another person does 946 00:34:51,764 --> 00:34:54,005 today is different from what they will do 947 00:34:54,005 --> 00:34:55,704 tomorrow and what you will do today. 948 00:34:56,324 --> 00:34:58,964 So it's an extremely stochastic system. And the 949 00:34:58,964 --> 00:35:00,264 the key idea 950 00:35:00,964 --> 00:35:03,444 of of our work was to explore this 951 00:35:03,444 --> 00:35:06,659 system, collecting as much data as possible, in 952 00:35:06,739 --> 00:35:08,920 this case, in a train station. Now imagine 953 00:35:09,299 --> 00:35:09,780 tracking, 954 00:35:10,179 --> 00:35:12,579 all the people passing in this train station 955 00:35:12,579 --> 00:35:13,719 for, like, 1 year. 956 00:35:14,179 --> 00:35:17,219 Now we we speak about, 100,000 people per 957 00:35:17,219 --> 00:35:17,719 day, 958 00:35:18,339 --> 00:35:20,819 roughly speaking. So you you multiply this by 959 00:35:20,819 --> 00:35:23,965 360 days. You are immediately in the 960 00:35:24,344 --> 00:35:24,925 the millions 961 00:35:26,664 --> 00:35:27,164 scale. 962 00:35:27,545 --> 00:35:29,085 Well, many millions of scale. 963 00:35:29,945 --> 00:35:30,425 And then, 964 00:35:30,985 --> 00:35:33,804 the endeavor was or the endeavor still is 965 00:35:33,945 --> 00:35:34,925 to find 966 00:35:36,119 --> 00:35:39,739 universal pattern or universal physical features that emerge 967 00:35:39,960 --> 00:35:41,159 as we look at this, 968 00:35:41,480 --> 00:35:42,839 dynamical system at this, 969 00:35:43,319 --> 00:35:44,460 this large scale. 970 00:35:45,239 --> 00:35:45,739 And 971 00:35:46,199 --> 00:35:47,019 let's say 972 00:35:47,319 --> 00:35:49,159 you need to start simple. Right? So this 973 00:35:49,159 --> 00:35:51,295 is a this is a extremely complex system. 974 00:35:51,295 --> 00:35:52,815 So we start simple. And, 975 00:35:53,454 --> 00:35:55,875 so first first step is to look at 976 00:35:56,494 --> 00:35:59,775 how individual particles, let's say, individual pedestrian move, 977 00:35:59,775 --> 00:36:00,914 what is their statistical 978 00:36:01,215 --> 00:36:03,659 fingerprint. So how can you describe this with 979 00:36:03,659 --> 00:36:05,839 the with the stochastic differential equation? 980 00:36:06,460 --> 00:36:07,199 And, specifically, 981 00:36:07,739 --> 00:36:09,119 the ignoble was 982 00:36:09,500 --> 00:36:11,739 centered around the, let's say, the volume 2 983 00:36:11,739 --> 00:36:13,659 that is, when you move from a single 984 00:36:13,659 --> 00:36:15,679 particle to 2 particles interacting. 985 00:36:16,065 --> 00:36:16,964 So we did, 986 00:36:17,264 --> 00:36:17,764 something, 987 00:36:18,065 --> 00:36:20,864 let's say, in some sense inspired by by 988 00:36:20,864 --> 00:36:24,065 by impact parameter studies in in scattering physics. 989 00:36:24,065 --> 00:36:25,664 That is imagine that now you have 2 990 00:36:25,664 --> 00:36:27,045 particles that that 991 00:36:27,425 --> 00:36:27,824 are, 992 00:36:28,304 --> 00:36:31,320 walking or are moving in opposite direction. And 993 00:36:31,320 --> 00:36:32,619 then, I mean, 994 00:36:33,640 --> 00:36:34,140 obviously, 995 00:36:34,840 --> 00:36:37,239 you don't collide typically with with the particle 996 00:36:37,239 --> 00:36:39,239 coming in in in the opposite direction. And 997 00:36:39,239 --> 00:36:41,739 so there is, there is a whole avoidance 998 00:36:41,800 --> 00:36:44,059 mechanism that is that is triggered. 999 00:36:44,904 --> 00:36:47,244 And we characterize this avoidance mechanism 1000 00:36:47,545 --> 00:36:49,784 looking, again in the in the hundreds of 1001 00:36:49,784 --> 00:36:50,844 thousands of trajectories. 1002 00:36:51,304 --> 00:36:53,625 And, and we wrote the differential equation that 1003 00:36:53,625 --> 00:36:56,585 reproduce the same statistical fingerprint. So what happens 1004 00:36:57,590 --> 00:36:59,590 So what are the the the the common 1005 00:36:59,590 --> 00:37:00,829 way in which this process, 1006 00:37:01,269 --> 00:37:01,769 happens? 1007 00:37:02,869 --> 00:37:04,630 The fact that every now and then there 1008 00:37:04,630 --> 00:37:06,409 are indeed collisions and 1009 00:37:06,710 --> 00:37:09,269 how, let's say, the interaction decays in space 1010 00:37:09,269 --> 00:37:11,994 and and so on. Okay. Okay. So, like, 1011 00:37:11,994 --> 00:37:14,635 for example, one one time, I was walking 1012 00:37:14,635 --> 00:37:17,434 along Tottenham Court Road in London. A taxi 1013 00:37:17,434 --> 00:37:19,054 pulled up. I wasn't concentrating. 1014 00:37:19,434 --> 00:37:21,034 It was before I had a mobile phone, 1015 00:37:21,034 --> 00:37:22,235 so I wasn't looking at that. I don't 1016 00:37:22,235 --> 00:37:24,000 know. I was probably looking at a a 1017 00:37:24,000 --> 00:37:26,159 Lego shop or something. And, the, 1018 00:37:26,640 --> 00:37:28,559 the door opened of the of the taxi 1019 00:37:28,559 --> 00:37:30,800 without me noticing, and somebody stepped out, and 1020 00:37:30,800 --> 00:37:31,860 I bumped into, 1021 00:37:32,880 --> 00:37:35,599 that person. And that person was Billy Piper, 1022 00:37:35,599 --> 00:37:37,119 who at the time was in doctor who, 1023 00:37:37,119 --> 00:37:38,864 which was terribly exciting for me. 1024 00:37:39,425 --> 00:37:41,664 I imagine it wasn't terribly exciting for her. 1025 00:37:41,664 --> 00:37:43,264 So that kind of collision has had a 1026 00:37:43,264 --> 00:37:45,844 different reaction with the 2 different particles. 1027 00:37:46,144 --> 00:37:48,385 So one of those particles had a, you 1028 00:37:48,385 --> 00:37:48,885 know, 1029 00:37:49,344 --> 00:37:52,170 reaction of boredom and annoyance, and the other 1030 00:37:52,170 --> 00:37:53,469 one had a reaction 1031 00:37:53,769 --> 00:37:54,829 of excitement 1032 00:37:55,210 --> 00:37:57,309 and can't wait to tell its other particle 1033 00:37:57,369 --> 00:37:58,109 nerd friends 1034 00:37:58,489 --> 00:37:59,469 about the interaction. 1035 00:37:59,849 --> 00:38:01,469 Let's say this is, I think, 1036 00:38:03,210 --> 00:38:05,609 connected with with the other Nobel Prize that 1037 00:38:05,609 --> 00:38:07,744 has been that has been won the same 1038 00:38:07,744 --> 00:38:09,824 year by the group in Japan of of 1039 00:38:09,824 --> 00:38:11,525 Claudio Feliciani and the others. 1040 00:38:12,065 --> 00:38:14,864 And, yeah, they they started, let's say, the 1041 00:38:14,864 --> 00:38:15,925 the case in which 1042 00:38:16,864 --> 00:38:18,945 which people are not paying attention because they 1043 00:38:18,945 --> 00:38:21,900 are distracted by by mobile phones. And they 1044 00:38:21,900 --> 00:38:22,559 are examined 1045 00:38:23,179 --> 00:38:23,679 essentially 1046 00:38:24,059 --> 00:38:24,559 how 1047 00:38:24,859 --> 00:38:28,539 this interaction mechanism gets penalized as as people, 1048 00:38:28,780 --> 00:38:30,539 don't pay attention. What does it tell us 1049 00:38:30,539 --> 00:38:31,039 about 1050 00:38:31,659 --> 00:38:32,159 ourselves, 1051 00:38:32,940 --> 00:38:33,440 crowds, 1052 00:38:33,914 --> 00:38:37,215 or physics in more widely? Bumping or perhaps 1053 00:38:37,275 --> 00:38:38,175 not bumping 1054 00:38:38,474 --> 00:38:38,875 is, 1055 00:38:39,434 --> 00:38:39,934 is 1056 00:38:40,235 --> 00:38:42,954 the basic interaction mechanism that there is in 1057 00:38:42,954 --> 00:38:43,535 this type 1058 00:38:44,394 --> 00:38:46,289 of system. Let's say that that, you know, 1059 00:38:46,289 --> 00:38:48,309 as physicists or as applied mathematician, 1060 00:38:48,610 --> 00:38:50,690 what mathematicians, what we'd like to do is 1061 00:38:50,690 --> 00:38:53,250 start from something complex. Right? We have many 1062 00:38:53,250 --> 00:38:54,849 agents, many people, and so on and so 1063 00:38:54,849 --> 00:38:56,070 forth, and we try to 1064 00:38:56,929 --> 00:38:59,910 reduce it using, the language of of mathematical 1065 00:39:00,050 --> 00:39:01,590 physics. Right? And so immediately, 1066 00:39:02,984 --> 00:39:05,704 you you would reduce a system of interacting 1067 00:39:05,704 --> 00:39:08,264 pedestrians into a system of particles that, in 1068 00:39:08,264 --> 00:39:09,085 a way or another, 1069 00:39:09,545 --> 00:39:09,784 have, 1070 00:39:10,344 --> 00:39:13,385 interactions that are in some sense similar to 1071 00:39:13,385 --> 00:39:14,684 gravity, but probably 1072 00:39:15,429 --> 00:39:17,750 anti gravity. Right? So you repel each other 1073 00:39:17,750 --> 00:39:18,489 instead of, 1074 00:39:19,269 --> 00:39:19,769 attracting, 1075 00:39:20,309 --> 00:39:22,150 each other. And, and, 1076 00:39:23,590 --> 00:39:24,789 the interesting thing, 1077 00:39:25,190 --> 00:39:25,849 is that 1078 00:39:28,284 --> 00:39:30,144 considering a a particle system 1079 00:39:30,445 --> 00:39:32,364 with with this very basic, 1080 00:39:33,005 --> 00:39:34,144 repulsion mechanism, 1081 00:39:35,324 --> 00:39:36,704 is enough to recover 1082 00:39:37,005 --> 00:39:37,985 some of the 1083 00:39:38,684 --> 00:39:39,824 qualitative features 1084 00:39:40,284 --> 00:39:42,204 of this system. So you might be aware 1085 00:39:42,204 --> 00:39:43,505 of of of the following. 1086 00:39:44,269 --> 00:39:46,609 This is a very, very much used case 1087 00:39:46,750 --> 00:39:49,070 to explain some of this emergent behavior that 1088 00:39:49,070 --> 00:39:50,829 you have in this in this crowd system. 1089 00:39:50,829 --> 00:39:51,469 Right? So, 1090 00:39:51,869 --> 00:39:53,789 okay. Okay. Maybe let let me add something 1091 00:39:53,789 --> 00:39:54,289 that, 1092 00:39:55,150 --> 00:39:58,184 one of the the connection point between between 1093 00:39:58,425 --> 00:40:01,144 crowd dynamics and and physics is in the 1094 00:40:01,144 --> 00:40:03,704 direction of complex system. Right? So complex system 1095 00:40:03,704 --> 00:40:04,364 is about, 1096 00:40:05,305 --> 00:40:08,105 how, let's say, complex pattern or complex structure 1097 00:40:08,105 --> 00:40:09,085 emerge as 1098 00:40:09,385 --> 00:40:09,885 basic 1099 00:40:10,659 --> 00:40:12,900 entities interact with simple rules. So the fact 1100 00:40:12,900 --> 00:40:15,780 that you can get macroscopically nontrivial patterns out 1101 00:40:15,780 --> 00:40:16,760 of basic 1102 00:40:17,219 --> 00:40:19,880 rules between many, many agents. And in crowds, 1103 00:40:20,179 --> 00:40:21,059 the very basic, 1104 00:40:21,539 --> 00:40:24,360 emergent behavior that is considered is the following. 1105 00:40:24,500 --> 00:40:25,960 So imagine that you have 1106 00:40:27,394 --> 00:40:30,034 a crowd of people, let's say, with with 1107 00:40:30,034 --> 00:40:33,094 red shirts that are moving along 1 one 1108 00:40:34,675 --> 00:40:37,315 one street from one side to another and 1109 00:40:37,315 --> 00:40:39,474 another crowd of people with blue shirts that 1110 00:40:39,474 --> 00:40:41,235 are moving on the same street but in 1111 00:40:41,235 --> 00:40:43,369 the opposite direction. Okay? So now you have 1112 00:40:43,369 --> 00:40:45,930 the 2 big crowds, and they're facing each 1113 00:40:45,930 --> 00:40:46,829 other and walking 1114 00:40:47,289 --> 00:40:49,610 in in opposite direction. And then the very 1115 00:40:49,610 --> 00:40:50,110 basic, 1116 00:40:51,289 --> 00:40:53,869 emergent behavior that this system has is that 1117 00:40:55,144 --> 00:40:55,644 particles, 1118 00:40:56,344 --> 00:40:58,284 or or people that have 1119 00:40:58,824 --> 00:41:00,344 that are going in the same direction, which 1120 00:41:00,344 --> 00:41:02,344 means that they they come with a a 1121 00:41:02,344 --> 00:41:03,644 shirt of the same color, 1122 00:41:04,264 --> 00:41:07,224 would align in stripes. So now imagine yourself 1123 00:41:07,224 --> 00:41:09,085 looking up. Now these 2 crowds 1124 00:41:09,860 --> 00:41:12,019 walked, and now they are crossing each other. 1125 00:41:12,019 --> 00:41:14,179 But then you wouldn't observe that, the system 1126 00:41:14,179 --> 00:41:16,900 is completely disordered, so you wouldn't observe completely 1127 00:41:16,900 --> 00:41:19,619 random distribution of red, of red and blue 1128 00:41:19,619 --> 00:41:20,119 shirts. 1129 00:41:20,739 --> 00:41:22,119 You would rather observe 1130 00:41:22,494 --> 00:41:24,514 the fact that the system has ordered 1131 00:41:25,214 --> 00:41:26,594 in in in stripes 1132 00:41:26,894 --> 00:41:29,054 of shirts of the same color, meaning of 1133 00:41:29,054 --> 00:41:31,214 stripes of people going in the same same 1134 00:41:31,214 --> 00:41:34,195 direction. And the the fascinating thing is that 1135 00:41:35,789 --> 00:41:36,289 it's 1136 00:41:37,230 --> 00:41:37,730 extremely 1137 00:41:38,110 --> 00:41:42,030 well, it's surprisingly simple to regenerate or to 1138 00:41:42,030 --> 00:41:42,530 to, 1139 00:41:43,150 --> 00:41:44,210 explain, to reproduce 1140 00:41:44,590 --> 00:41:45,730 this emerging behavior 1141 00:41:46,030 --> 00:41:46,769 by just 1142 00:41:47,150 --> 00:41:50,050 having particle moving in opposite direction that 1143 00:41:50,765 --> 00:41:53,325 know only a single rule beside the the 1144 00:41:53,325 --> 00:41:54,684 the need of moving that is the need 1145 00:41:54,684 --> 00:41:57,164 of avoiding. So the need of not entering 1146 00:41:57,164 --> 00:42:00,045 into very string stronger contact. Right? So so 1147 00:42:00,045 --> 00:42:00,785 the mechanism 1148 00:42:01,164 --> 00:42:03,324 of not bumping into each other is already 1149 00:42:03,324 --> 00:42:05,184 enough to explain quite interesting 1150 00:42:06,250 --> 00:42:06,750 emergent, 1151 00:42:07,210 --> 00:42:09,130 emergent behavior. This is only one. Right? There 1152 00:42:09,130 --> 00:42:10,269 are there are others. 1153 00:42:10,730 --> 00:42:11,230 And, 1154 00:42:12,809 --> 00:42:15,050 Yeah. Yeah. It took a very long road 1155 00:42:15,050 --> 00:42:17,610 here. Brilliant. So when you are you're doing 1156 00:42:17,610 --> 00:42:20,025 all of this research into into crowds, what 1157 00:42:20,025 --> 00:42:22,684 what's your goal? There are multiple goals. So, 1158 00:42:23,144 --> 00:42:25,065 let's say, as a physicist, there is the 1159 00:42:25,065 --> 00:42:26,764 challenge of of explaining 1160 00:42:27,065 --> 00:42:28,204 something that is 1161 00:42:28,984 --> 00:42:31,464 extremely complex, extremely stochastic. So there is the 1162 00:42:31,464 --> 00:42:33,804 the the underlying question, can we put down 1163 00:42:34,329 --> 00:42:37,609 physical rules that that regulate this system? And 1164 00:42:37,609 --> 00:42:39,609 here, one needs to go deep enough because, 1165 00:42:39,609 --> 00:42:42,030 obviously, you cannot expect to have a mathematical 1166 00:42:42,089 --> 00:42:44,569 model that reproduces what one person does because 1167 00:42:44,569 --> 00:42:45,469 this is obviously, 1168 00:42:46,170 --> 00:42:48,109 I mean, meaningless. So this is completely 1169 00:42:48,914 --> 00:42:51,155 senseless because it's just unpredictable. But then, 1170 00:42:52,114 --> 00:42:54,775 in in our case, going deep enough means 1171 00:42:55,394 --> 00:42:56,375 having enough 1172 00:42:57,474 --> 00:42:57,974 data 1173 00:42:58,275 --> 00:42:59,255 of this system, 1174 00:43:00,195 --> 00:43:03,130 in such a way that that statistical fingerprint 1175 00:43:03,190 --> 00:43:05,750 emerged. Like, the fact that the average behavior 1176 00:43:05,750 --> 00:43:07,590 of the system is this. The fluctuation the 1177 00:43:07,590 --> 00:43:10,550 typical fluctuation is that. Events that happen 1 1178 00:43:10,550 --> 00:43:12,630 in 1,000 are these and these and these. 1179 00:43:12,630 --> 00:43:14,550 Events that happen 1 in 10000 are these 1180 00:43:14,550 --> 00:43:15,829 and these and these. And I think at 1181 00:43:15,829 --> 00:43:16,969 this point, it becomes 1182 00:43:17,385 --> 00:43:20,184 not so surprising the fact that about this 1183 00:43:20,184 --> 00:43:21,644 behavior, one can write, 1184 00:43:22,105 --> 00:43:23,085 can write physical, 1185 00:43:23,545 --> 00:43:24,045 equations. 1186 00:43:24,985 --> 00:43:28,425 And, and, and this aligns with, again, topics 1187 00:43:28,425 --> 00:43:31,244 such as, physics of active matter that is, 1188 00:43:32,059 --> 00:43:33,920 the physics that study all sort 1189 00:43:34,460 --> 00:43:36,059 of matter that in a way or another 1190 00:43:36,059 --> 00:43:38,619 is capable of of turning internal energy into 1191 00:43:38,619 --> 00:43:39,519 motion spontaneously. 1192 00:43:39,900 --> 00:43:41,360 Right? So we go from, 1193 00:43:41,820 --> 00:43:42,320 bacteria. 1194 00:43:42,940 --> 00:43:45,019 We go from, we consider, I don't know, 1195 00:43:45,019 --> 00:43:46,000 flocks of birds, 1196 00:43:47,994 --> 00:43:50,394 and so in general animal behavior and so 1197 00:43:50,394 --> 00:43:52,974 on. It aligns with the physics of complexity 1198 00:43:53,114 --> 00:43:54,335 that is, how, 1199 00:43:54,635 --> 00:43:55,775 as I said, how 1200 00:43:56,074 --> 00:43:59,034 nontrivial pattern emerged from simple inter from simple 1201 00:43:59,034 --> 00:43:59,534 interaction. 1202 00:43:59,914 --> 00:44:02,929 And this this case also, especially when we 1203 00:44:02,929 --> 00:44:04,769 go in a high density regime, it can 1204 00:44:04,769 --> 00:44:07,570 align with with, some condensed matter structure. So 1205 00:44:07,650 --> 00:44:09,650 but in general, there are there are very 1206 00:44:09,650 --> 00:44:12,630 many connections with different fields of physics. 1207 00:44:13,265 --> 00:44:15,045 And then, of course, there is also the 1208 00:44:15,105 --> 00:44:16,085 the the societal 1209 00:44:16,465 --> 00:44:18,785 slash engineering component that is, 1210 00:44:19,184 --> 00:44:21,265 now we get to have a model that 1211 00:44:21,265 --> 00:44:23,765 that is capable of reproducing the the stochastic 1212 00:44:23,824 --> 00:44:25,905 dynamics of the system. How about we use 1213 00:44:25,905 --> 00:44:26,724 it to 1214 00:44:27,880 --> 00:44:31,340 in design phase perhaps of of a facility? 1215 00:44:31,719 --> 00:44:33,400 Or we use this to do real time 1216 00:44:33,400 --> 00:44:35,719 control, which are things that actually are happening. 1217 00:44:35,719 --> 00:44:38,440 So let's say you observe your system at 1218 00:44:38,440 --> 00:44:40,554 a very large scale, and then you you 1219 00:44:40,554 --> 00:44:42,474 have a model that tries to predict what's 1220 00:44:42,474 --> 00:44:43,994 most likely going to happen in the next 1221 00:44:43,994 --> 00:44:46,155 5, 10 minutes, and then you use this 1222 00:44:46,155 --> 00:44:49,114 to to nudge. Right? So to to exert 1223 00:44:49,114 --> 00:44:50,715 some action in the system in such a 1224 00:44:50,715 --> 00:44:53,570 way that that it behaves as it, I 1225 00:44:53,570 --> 00:44:55,809 mean, to increase safety, for instance, or or 1226 00:44:55,809 --> 00:44:58,690 or comfort. And this, this is this might 1227 00:44:58,690 --> 00:45:00,389 sound science fiction, but this 1228 00:45:00,769 --> 00:45:01,829 is active research 1229 00:45:02,289 --> 00:45:04,289 on one hand, and already there are many 1230 00:45:04,289 --> 00:45:06,610 attempts in this direction already on the other. 1231 00:45:06,610 --> 00:45:08,594 So Yeah. Do you do you have any 1232 00:45:08,835 --> 00:45:10,454 examples of where it's been? 1233 00:45:11,315 --> 00:45:11,795 Well, 1234 00:45:12,195 --> 00:45:14,275 I can I can connect, with with my 1235 00:45:14,275 --> 00:45:14,775 research? 1236 00:45:15,795 --> 00:45:17,014 For instance, we're investigating, 1237 00:45:17,635 --> 00:45:19,175 the usage of of illumination 1238 00:45:20,114 --> 00:45:20,934 to nudge, 1239 00:45:22,275 --> 00:45:23,414 people into, 1240 00:45:24,829 --> 00:45:26,050 let's say, actually, 1241 00:45:26,989 --> 00:45:29,809 into distributing in space to maximize 1242 00:45:30,190 --> 00:45:31,250 some some property. 1243 00:45:33,150 --> 00:45:35,230 A typical application would be, for instance, in 1244 00:45:35,230 --> 00:45:37,090 museums. Right? So you would like 1245 00:45:37,715 --> 00:45:39,894 floor usage, to be uniform, 1246 00:45:40,755 --> 00:45:41,735 and not, that, 1247 00:45:42,114 --> 00:45:44,755 you know, your crowd is fully concentrated in 1248 00:45:44,755 --> 00:45:46,594 one room and then all the rest of 1249 00:45:46,594 --> 00:45:47,655 the museum is, 1250 00:45:48,034 --> 00:45:48,534 empty. 1251 00:45:49,795 --> 00:45:52,450 We've been working with, with with sound with 1252 00:45:52,450 --> 00:45:54,869 positional sound as well. Let's say you, 1253 00:45:56,050 --> 00:45:57,349 only in certain location, 1254 00:45:57,650 --> 00:45:59,030 you can hear some sound. 1255 00:45:59,570 --> 00:46:01,969 And, only for instance, if you have a 1256 00:46:01,969 --> 00:46:03,650 complete track this is something that we we 1257 00:46:03,650 --> 00:46:05,989 published recently that, let's say, 1258 00:46:06,974 --> 00:46:10,114 only if you are walking a specific trajectory, 1259 00:46:10,255 --> 00:46:12,835 you could hear a full, let's say, melody. 1260 00:46:13,214 --> 00:46:13,714 Right? 1261 00:46:14,094 --> 00:46:14,414 And, 1262 00:46:15,054 --> 00:46:17,135 and if you steer out from this, let's 1263 00:46:17,135 --> 00:46:20,034 say, target trajectory, you stop hearing the melody. 1264 00:46:20,190 --> 00:46:22,670 And so there we show that actually we 1265 00:46:22,670 --> 00:46:25,550 could have people following the the, let's say, 1266 00:46:25,550 --> 00:46:26,609 the target trajectory 1267 00:46:26,909 --> 00:46:28,909 due to the fact that there was, an 1268 00:46:28,909 --> 00:46:30,909 expectation by people of keep on hearing the 1269 00:46:30,909 --> 00:46:33,550 melody. You know? So it's like every step 1270 00:46:33,550 --> 00:46:34,530 you hear a different 1271 00:46:35,614 --> 00:46:38,194 tone. Right? And then people would be, 1272 00:46:39,214 --> 00:46:40,194 I mean, spontaneously, 1273 00:46:40,574 --> 00:46:42,494 you would like to hear what you expect 1274 00:46:42,494 --> 00:46:44,494 to be the next tone. Right? So imagine 1275 00:46:44,494 --> 00:46:45,694 that there is a there is a simple 1276 00:46:45,694 --> 00:46:48,014 melody, and and this enable us to to 1277 00:46:48,014 --> 00:46:49,610 push people to to follow, 1278 00:46:50,309 --> 00:46:52,470 certain trajectories. But but there is more. I 1279 00:46:52,470 --> 00:46:53,289 mean, there are 1280 00:46:53,670 --> 00:46:55,769 things that are very unexpected. And, 1281 00:46:56,630 --> 00:46:59,349 I mean, let's say at times, you are 1282 00:46:59,349 --> 00:47:01,590 maybe in a train station and and and 1283 00:47:01,590 --> 00:47:04,085 you are annoyed by the fact that your 1284 00:47:04,085 --> 00:47:04,984 mobile phone 1285 00:47:06,405 --> 00:47:08,585 is is is not connecting to the Internet. 1286 00:47:08,964 --> 00:47:10,885 And this is not because there was no 1287 00:47:10,885 --> 00:47:13,284 Internet there, but because the signal is locally 1288 00:47:13,284 --> 00:47:13,784 jammed 1289 00:47:14,405 --> 00:47:16,244 to make sure to make sure that people 1290 00:47:16,244 --> 00:47:17,864 don't clog in a 1291 00:47:18,200 --> 00:47:19,579 in a given, location. 1292 00:47:20,599 --> 00:47:22,360 Let's say we don't want people to stand 1293 00:47:22,360 --> 00:47:24,920 here because maybe the the the flow would 1294 00:47:24,920 --> 00:47:26,619 would would clog. Right? Imagine, 1295 00:47:27,320 --> 00:47:30,119 there is a staircase perhaps, and then people 1296 00:47:30,119 --> 00:47:32,200 would would climb the staircase and just wait 1297 00:47:32,200 --> 00:47:33,320 there. But obviously 1298 00:47:34,125 --> 00:47:36,364 and let's say that this this staircase leads 1299 00:47:36,364 --> 00:47:38,445 to to the platform of a train station. 1300 00:47:38,445 --> 00:47:40,525 Yeah? And, obviously, you don't want people just 1301 00:47:40,525 --> 00:47:42,204 to to climb the stairs and and wait 1302 00:47:42,204 --> 00:47:44,045 there. You would like them to distribute on 1303 00:47:44,045 --> 00:47:44,625 the platform. 1304 00:47:45,244 --> 00:47:47,744 And, so how do you ensure that? 1305 00:47:48,219 --> 00:47:50,380 Then you would locally jam the mobile phone 1306 00:47:50,380 --> 00:47:51,920 signal in front of the staircase. 1307 00:47:53,099 --> 00:47:55,820 And now and now, you know, the person 1308 00:47:55,820 --> 00:47:57,820 would would climb the stairs and then they 1309 00:47:57,820 --> 00:47:59,579 would just stand there and get out their 1310 00:47:59,579 --> 00:48:01,599 mobile phone and then they figure, oh, 1311 00:48:01,925 --> 00:48:02,824 it's not working. 1312 00:48:03,204 --> 00:48:05,045 Right? And then I move around to to 1313 00:48:05,045 --> 00:48:07,065 get it to work. But, yeah, 1314 00:48:07,525 --> 00:48:09,945 it was not it wasn't working not because 1315 00:48:10,324 --> 00:48:12,324 there was no signal. It was on purpose. 1316 00:48:12,324 --> 00:48:14,760 You know, you know and then it was 1317 00:48:14,760 --> 00:48:16,880 not the efficiency of the mobile phone company. 1318 00:48:16,880 --> 00:48:19,000 It was rather by design that you were 1319 00:48:19,000 --> 00:48:19,239 not, 1320 00:48:19,960 --> 00:48:21,960 That's amazing. Is that something that's going to 1321 00:48:21,960 --> 00:48:22,460 happen? 1322 00:48:23,000 --> 00:48:24,840 No. This is something that is happening already. 1323 00:48:24,840 --> 00:48:26,860 Really? Tell you this. Yes. Genuinely. 1324 00:48:27,160 --> 00:48:30,265 People are using people are blocking that. So, 1325 00:48:30,265 --> 00:48:32,344 basically, at halftime in the football, right, I 1326 00:48:32,344 --> 00:48:33,625 I sit there and try and check the 1327 00:48:33,625 --> 00:48:34,684 scores from elsewhere, 1328 00:48:35,065 --> 00:48:37,304 and it it you just can't because everybody's 1329 00:48:37,304 --> 00:48:39,784 doing exactly the same thing. Happily, in my 1330 00:48:39,784 --> 00:48:40,284 own, 1331 00:48:41,429 --> 00:48:43,190 football club that I support, they provide Wi 1332 00:48:43,190 --> 00:48:45,269 Fi, which does the job quite nicely. And 1333 00:48:45,269 --> 00:48:46,809 and they put the scores on the screen. 1334 00:48:46,949 --> 00:48:49,349 But there it does happen that it's blocked 1335 00:48:49,349 --> 00:48:51,030 because there's a number of people in it 1336 00:48:51,030 --> 00:48:52,469 as well. Right? Just so people are listening 1337 00:48:52,469 --> 00:48:54,150 and not thinking every time it's blocked, it's 1338 00:48:54,150 --> 00:48:56,150 some mobile phone company trying to move them 1339 00:48:56,150 --> 00:48:56,445 on. 1340 00:48:57,005 --> 00:48:58,364 Well, no. No. No. I mean, like, yeah. 1341 00:48:58,364 --> 00:48:59,644 Of course of course, there you have a 1342 00:48:59,644 --> 00:49:01,485 you have a network capacity issue. I I 1343 00:49:01,485 --> 00:49:03,885 think these these are different things. Here, I 1344 00:49:03,885 --> 00:49:05,565 mean, there is a possibility of doing very 1345 00:49:05,565 --> 00:49:07,644 local jamming. Right? The the the within a 1346 00:49:07,644 --> 00:49:11,339 within a very limited area, mobile phone is 1347 00:49:11,339 --> 00:49:11,579 is 1348 00:49:12,139 --> 00:49:14,460 reception is not is not good. But, again, 1349 00:49:14,460 --> 00:49:16,559 this is this is already in in place. 1350 00:49:16,779 --> 00:49:18,400 And, that's extraordinary. 1351 00:49:18,859 --> 00:49:20,940 That's extraordinary. Well, can you tell me just 1352 00:49:20,940 --> 00:49:22,799 going back to the light bit, the illumination 1353 00:49:22,940 --> 00:49:24,319 bit in the museum? Right. 1354 00:49:24,855 --> 00:49:26,375 How does that would we are you sort 1355 00:49:26,375 --> 00:49:28,775 of eliminating particular bits to draw people in? 1356 00:49:28,775 --> 00:49:30,454 Are you dimming bits? Yeah. We we we 1357 00:49:30,454 --> 00:49:32,554 ran a couple of of big experiments, 1358 00:49:33,815 --> 00:49:35,175 around here. Is, 1359 00:49:36,775 --> 00:49:37,594 is the question, 1360 00:49:38,960 --> 00:49:40,659 can we use light 1361 00:49:41,119 --> 00:49:41,619 to 1362 00:49:42,079 --> 00:49:43,059 to to provide 1363 00:49:43,679 --> 00:49:44,179 information 1364 00:49:44,480 --> 00:49:45,119 that is, 1365 00:49:45,759 --> 00:49:46,719 to convey, let's say 1366 00:49:47,440 --> 00:49:48,559 I I don't want to use the word 1367 00:49:48,559 --> 00:49:50,099 subtle, but to convey, 1368 00:49:50,559 --> 00:49:52,019 let's say, more and more implicit 1369 00:49:52,400 --> 00:49:53,920 information. And it works, 1370 00:49:54,465 --> 00:49:56,065 or at least the experiment that we did, 1371 00:49:56,305 --> 00:49:58,164 were based on on on dimming. 1372 00:49:58,785 --> 00:49:59,184 And, 1373 00:49:59,744 --> 00:50:01,525 we showed indeed the following 1374 00:50:01,985 --> 00:50:02,485 that, 1375 00:50:04,385 --> 00:50:06,485 imagine you have you have this big crowd. 1376 00:50:06,545 --> 00:50:09,179 We did this, in in this very experiment 1377 00:50:09,179 --> 00:50:10,940 that I'm referring to was that was run 1378 00:50:10,940 --> 00:50:12,780 during a big festival that we have here 1379 00:50:12,780 --> 00:50:13,440 in Andover. 1380 00:50:13,739 --> 00:50:14,559 So it's it's, 1381 00:50:15,579 --> 00:50:17,739 city walk throughout the entire city, let's say. 1382 00:50:17,739 --> 00:50:18,880 So, again, 1383 00:50:19,579 --> 00:50:21,039 tens of thousands of people. 1384 00:50:21,505 --> 00:50:24,385 And now imagine these these people all entering 1385 00:50:24,385 --> 00:50:26,085 into a corridor, then, 1386 00:50:26,625 --> 00:50:28,625 we wanted them to go, let's say, to 1387 00:50:28,625 --> 00:50:31,204 choose either the left or the right exit. 1388 00:50:32,224 --> 00:50:32,724 And, 1389 00:50:34,489 --> 00:50:37,369 in our experiment, we compared our effective it 1390 00:50:37,369 --> 00:50:39,609 is to show people, for instance, a normal 1391 00:50:39,609 --> 00:50:42,089 signage, so big arrow that says, okay. Go 1392 00:50:42,089 --> 00:50:43,789 left rather than go right. 1393 00:50:44,250 --> 00:50:44,750 Or 1394 00:50:45,609 --> 00:50:48,805 rather to change the illumination level between the 1395 00:50:48,805 --> 00:50:51,445 two ends or the two exits. Yeah. And 1396 00:50:51,445 --> 00:50:52,825 then we show that that, 1397 00:50:53,204 --> 00:50:54,184 within some, 1398 00:50:54,644 --> 00:50:56,405 let's say, crowd density limit, 1399 00:50:56,965 --> 00:50:59,204 you can have more or less the same 1400 00:50:59,204 --> 00:50:59,704 effectiveness 1401 00:51:00,164 --> 00:51:00,565 in, 1402 00:51:01,045 --> 00:51:01,545 in 1403 00:51:02,619 --> 00:51:04,139 light and signage have more or less the 1404 00:51:04,139 --> 00:51:04,800 same effectiveness. 1405 00:51:05,099 --> 00:51:07,359 And then it happens that as cloud density, 1406 00:51:08,539 --> 00:51:09,039 grows, 1407 00:51:09,579 --> 00:51:10,800 as as you can expect, 1408 00:51:11,260 --> 00:51:13,340 there is no indication that is really followed. 1409 00:51:13,340 --> 00:51:14,859 It doesn't matter whether it is based on 1410 00:51:14,859 --> 00:51:16,695 light or signage. It's it's like, 1411 00:51:17,175 --> 00:51:19,015 I mean, people at certain point when there 1412 00:51:19,015 --> 00:51:21,094 are these many in a confined space, they 1413 00:51:21,094 --> 00:51:22,535 just need to get out. So it doesn't 1414 00:51:22,535 --> 00:51:24,695 matter whether there is an indication that points 1415 00:51:24,695 --> 00:51:25,835 there them somewhere. 1416 00:51:26,535 --> 00:51:28,235 But but, let's say, within 1417 00:51:28,855 --> 00:51:29,355 operational, 1418 00:51:29,894 --> 00:51:31,914 density level that you can find 1419 00:51:32,300 --> 00:51:33,739 in museums and so on and so forth. 1420 00:51:33,739 --> 00:51:35,900 So in our experiment, we could show that 1421 00:51:35,900 --> 00:51:38,139 that you can convey the same type of, 1422 00:51:40,059 --> 00:51:41,980 signal or you can convey a signal that 1423 00:51:41,980 --> 00:51:43,840 that has the same effect on people, 1424 00:51:44,539 --> 00:51:45,440 either by using 1425 00:51:46,734 --> 00:51:48,894 variable light intensity or or, 1426 00:51:49,534 --> 00:51:51,054 signage. Could you tell me a bit more 1427 00:51:51,054 --> 00:51:53,135 as well about the the the audio version? 1428 00:51:53,135 --> 00:51:54,655 Do do you have the melody? In the 1429 00:51:54,655 --> 00:51:56,335 paper, you could find the 4 the 4 1430 00:51:56,335 --> 00:51:56,835 tunes. 1431 00:51:57,375 --> 00:51:58,335 It was it was, 1432 00:51:59,054 --> 00:51:59,554 really 1433 00:52:00,335 --> 00:52:03,269 piano chords. Yeah. Oh, okay. I'm literally sitting 1434 00:52:03,269 --> 00:52:05,030 at a piano right now. So Okay. So 1435 00:52:05,430 --> 00:52:06,789 we could see. Yeah. I I I yeah. 1436 00:52:06,789 --> 00:52:08,710 I I think yeah. If you want, I 1437 00:52:08,710 --> 00:52:10,550 can I can look for it even right 1438 00:52:10,550 --> 00:52:12,390 now? But it's, let's say in this paper, 1439 00:52:12,390 --> 00:52:13,849 then then you would see that 1440 00:52:14,175 --> 00:52:16,114 we divided the space into 1441 00:52:16,414 --> 00:52:19,695 areas, and then each area, each small area, 1442 00:52:19,695 --> 00:52:22,175 something like maybe half a meter times half 1443 00:52:22,175 --> 00:52:22,835 a meter, 1444 00:52:23,375 --> 00:52:24,335 came with different, 1445 00:52:24,735 --> 00:52:25,235 piano 1446 00:52:26,414 --> 00:52:27,855 tune. Right? With a different, 1447 00:52:28,630 --> 00:52:31,429 and then this was played one after the 1448 00:52:31,429 --> 00:52:32,650 other should you be, 1449 00:52:33,030 --> 00:52:33,530 walking 1450 00:52:34,869 --> 00:52:37,590 along the right path. Yes. Otherwise, you you 1451 00:52:37,590 --> 00:52:39,530 wouldn't hear anything. And, 1452 00:52:40,605 --> 00:52:42,204 okay. I'm not a music person. Right? So 1453 00:52:42,204 --> 00:52:43,804 now I would say something that I hope 1454 00:52:43,804 --> 00:52:45,405 makes sense to you because it doesn't make 1455 00:52:45,405 --> 00:52:46,625 much sense to me. 1456 00:52:47,244 --> 00:52:48,784 The sequence was c4c5 1457 00:52:50,125 --> 00:52:50,784 and thene4e5 1458 00:52:52,045 --> 00:52:53,440 and then g4g5andc5c6. 1459 00:52:55,579 --> 00:52:57,900 So should you be following the right path, 1460 00:52:57,900 --> 00:52:59,519 you would be hearing this. 1461 00:53:09,844 --> 00:53:11,925 As when you're walking around in crowds, are 1462 00:53:11,925 --> 00:53:14,025 you sort of in a kind of Sherlock 1463 00:53:14,085 --> 00:53:17,285 mind palace with equations appearing in your peripheral 1464 00:53:17,285 --> 00:53:18,724 vision as you're walking, or are you just 1465 00:53:18,724 --> 00:53:20,470 kind of wondering how can we make this 1466 00:53:20,470 --> 00:53:22,890 better? Walking around is is mostly like, 1467 00:53:24,230 --> 00:53:26,309 about how to improve the models. So how 1468 00:53:26,309 --> 00:53:27,130 to include, 1469 00:53:28,390 --> 00:53:30,550 let's say, more factors in the models that, 1470 00:53:30,789 --> 00:53:32,390 that that we are using or that we 1471 00:53:32,390 --> 00:53:33,050 are making. 1472 00:53:34,295 --> 00:53:35,114 And I think, 1473 00:53:36,855 --> 00:53:37,755 yeah. I 1474 00:53:39,094 --> 00:53:40,614 mean so that there are very 1475 00:53:40,934 --> 00:53:43,255 there are a bunch of very interesting physical 1476 00:53:43,255 --> 00:53:45,734 directions that are let me make an example 1477 00:53:45,734 --> 00:53:47,734 that is more telling than others in in 1478 00:53:47,734 --> 00:53:50,039 in my view. That is, for instance, when 1479 00:53:50,039 --> 00:53:51,980 when a crowd walk, not necessarily 1480 00:53:52,360 --> 00:53:53,739 the interaction is cooperative. 1481 00:53:54,119 --> 00:53:56,200 Right? So imagine that that you would like 1482 00:53:56,200 --> 00:53:59,739 to to get, onto onto a train. Right? 1483 00:54:00,119 --> 00:54:02,235 And you would like to to be 1484 00:54:02,775 --> 00:54:04,394 inside the train first. 1485 00:54:06,375 --> 00:54:07,275 And this 1486 00:54:08,295 --> 00:54:10,775 eventually doesn't mean, for instance, that the people 1487 00:54:10,775 --> 00:54:12,775 that need to get into the train with 1488 00:54:12,775 --> 00:54:13,275 you, 1489 00:54:15,014 --> 00:54:15,514 altogether 1490 00:54:17,109 --> 00:54:19,510 will manage to get in in the most 1491 00:54:19,510 --> 00:54:20,409 efficient way. 1492 00:54:20,949 --> 00:54:22,010 Right? Because 1493 00:54:22,630 --> 00:54:23,130 typically, 1494 00:54:23,750 --> 00:54:26,550 the the behavior of of each particle here 1495 00:54:26,550 --> 00:54:27,690 is is competitive 1496 00:54:27,989 --> 00:54:31,074 instead of constructive. Right? So and then the 1497 00:54:31,074 --> 00:54:31,974 question arises, 1498 00:54:32,275 --> 00:54:33,954 so how to up deal with it, how 1499 00:54:33,954 --> 00:54:36,214 to model this? So what is the underlying 1500 00:54:36,275 --> 00:54:38,114 physics? How can we represent it? I think 1501 00:54:38,114 --> 00:54:39,554 this is, for instance, a very interesting, 1502 00:54:40,194 --> 00:54:40,994 a very interesting, 1503 00:54:41,315 --> 00:54:42,614 direction that is, 1504 00:54:43,210 --> 00:54:45,530 how to to consider this particle system in 1505 00:54:45,530 --> 00:54:46,430 which, which, 1506 00:54:46,969 --> 00:54:50,010 there is an interplay between between competition and 1507 00:54:50,010 --> 00:54:51,070 and and cooperation, 1508 00:54:52,010 --> 00:54:54,349 as the the context changes. 1509 00:54:54,650 --> 00:54:56,250 And so for instance, this is one of 1510 00:54:56,250 --> 00:54:58,784 the things that I'm asking myself lately. So 1511 00:54:59,264 --> 00:55:01,264 what are efficient way to deal with this 1512 00:55:01,264 --> 00:55:03,505 and then then the randomness in the crowds 1513 00:55:03,505 --> 00:55:05,284 and and and so on. 1514 00:55:05,585 --> 00:55:07,984 And about about the interest in general, I 1515 00:55:07,984 --> 00:55:08,484 think 1516 00:55:09,344 --> 00:55:11,045 I got into crowds because 1517 00:55:12,170 --> 00:55:14,329 I wanted to do I wanted to explore 1518 00:55:14,329 --> 00:55:16,829 a part of physics that had two characteristics. 1519 00:55:17,450 --> 00:55:18,590 And one that was, 1520 00:55:19,690 --> 00:55:20,190 close 1521 00:55:20,570 --> 00:55:22,890 to people, like, that was, that I could 1522 00:55:22,890 --> 00:55:23,390 communicate 1523 00:55:25,105 --> 00:55:25,925 easily about, 1524 00:55:27,025 --> 00:55:28,805 that was immediately impactful 1525 00:55:29,585 --> 00:55:30,244 in society. 1526 00:55:31,184 --> 00:55:32,724 That was new. Right? 1527 00:55:33,265 --> 00:55:35,364 Where new means that, that research, 1528 00:55:38,329 --> 00:55:39,150 let's say, 1529 00:55:39,449 --> 00:55:41,630 started not so long ago. I mean, for 1530 00:55:42,090 --> 00:55:44,090 crowds, I mean, obviously, I mean, crowds, you 1531 00:55:44,090 --> 00:55:45,929 know, have been I mean, people have been 1532 00:55:45,929 --> 00:55:48,170 trying to optimize, crowd flow from the times 1533 00:55:48,170 --> 00:55:50,684 of the Colosseum in Rome. Right? But nevertheless, 1534 00:55:51,065 --> 00:55:53,464 let's say physicists started to look very seriously 1535 00:55:53,464 --> 00:55:55,944 at crowds only since the beginning of nineties, 1536 00:55:55,944 --> 00:55:58,025 and the first experiments were since the beginning 1537 00:55:58,025 --> 00:55:59,864 of 2000. So I would say that this 1538 00:55:59,864 --> 00:56:01,244 is relatively new. 1539 00:56:01,625 --> 00:56:03,464 Wanted to do something something new and it's 1540 00:56:03,464 --> 00:56:04,605 also something that 1541 00:56:05,809 --> 00:56:08,530 being new enables to I mean, needs to 1542 00:56:08,530 --> 00:56:10,449 couple a lot of things. So how to 1543 00:56:10,449 --> 00:56:12,690 do experiment is still an open question. How 1544 00:56:12,690 --> 00:56:14,449 to model is an open question. How to 1545 00:56:14,449 --> 00:56:16,170 control is an open question. So it has 1546 00:56:16,170 --> 00:56:18,769 a very, very broad range of open questions. 1547 00:56:18,769 --> 00:56:20,230 And this gave me the 1548 00:56:20,684 --> 00:56:23,244 the opportunity to to to bridge many things 1549 00:56:23,244 --> 00:56:25,405 from the experimental part to the modeling part. 1550 00:56:25,405 --> 00:56:26,045 And this is, 1551 00:56:26,525 --> 00:56:28,765 yeah, also one of the reasons I enjoy 1552 00:56:28,765 --> 00:56:29,265 this. 1553 00:56:29,644 --> 00:56:31,724 I'm not sure whether I project the equations 1554 00:56:31,724 --> 00:56:32,945 in my mind, but 1555 00:56:33,324 --> 00:56:35,369 it goes in that direction for sure. I've 1556 00:56:35,530 --> 00:56:37,130 never spoken to anyone who's won the Ig 1557 00:56:37,130 --> 00:56:39,369 Nobel Prize before. How does that come about, 1558 00:56:39,369 --> 00:56:40,430 and how does it feel? 1559 00:56:41,530 --> 00:56:41,849 Well, 1560 00:56:42,570 --> 00:56:44,730 it works, in in the in the following 1561 00:56:44,730 --> 00:56:46,730 way that that you receive a mail from 1562 00:56:46,730 --> 00:56:47,550 some colleague 1563 00:56:48,010 --> 00:56:50,170 that you might or might not know that 1564 00:56:50,170 --> 00:56:50,670 tells. 1565 00:56:51,605 --> 00:56:52,105 Well, 1566 00:56:52,885 --> 00:56:54,885 well, typically, I think you you you don't 1567 00:56:54,885 --> 00:56:56,804 know the colleague and then, you receive this 1568 00:56:56,804 --> 00:56:57,304 email 1569 00:56:57,684 --> 00:57:00,005 this morning that says, hey. I read your 1570 00:57:00,005 --> 00:57:00,505 work. 1571 00:57:01,844 --> 00:57:03,764 It's very interesting. I'd like to ask you 1572 00:57:03,764 --> 00:57:05,764 some question. And then and then, 1573 00:57:07,160 --> 00:57:09,340 it goes more or less like, the famous 1574 00:57:09,400 --> 00:57:11,559 scene of the matrix, you know, the the 1575 00:57:11,559 --> 00:57:14,119 blue and red pill thing. So, okay, I'd 1576 00:57:14,119 --> 00:57:16,200 like to tell you that that, you got, 1577 00:57:16,920 --> 00:57:19,720 I mean, you have you won this, Nobel 1578 00:57:19,720 --> 00:57:20,940 Prize and then, 1579 00:57:23,445 --> 00:57:25,445 but you can talk with your colleagues and 1580 00:57:25,445 --> 00:57:27,465 decide whether or not to accept the price. 1581 00:57:27,684 --> 00:57:30,485 And then, you you, yeah, you contact again 1582 00:57:30,485 --> 00:57:32,325 this person that that wrote you in the 1583 00:57:32,325 --> 00:57:33,765 1st place and you go for the red 1584 00:57:33,765 --> 00:57:34,965 pill. And then it becomes 1585 00:57:35,420 --> 00:57:38,460 yeah, afterwards, it becomes obviously extremely interesting because 1586 00:57:38,460 --> 00:57:39,039 it's a 1587 00:57:39,660 --> 00:57:40,480 great opportunity 1588 00:57:40,780 --> 00:57:43,900 to to discuss with with very, very wide 1589 00:57:43,900 --> 00:57:45,280 audience from scientists 1590 00:57:45,579 --> 00:57:46,480 to to 1591 00:57:47,019 --> 00:57:49,840 popular science channel about about your work. Okay. 1592 00:57:49,905 --> 00:57:52,224 But so is that why you decided to 1593 00:57:52,224 --> 00:57:54,545 accept the prize because of that opportunity for 1594 00:57:54,545 --> 00:57:55,925 communicating about your work? 1595 00:57:56,465 --> 00:57:58,864 Well, this is definitely well, because it's a 1596 00:57:58,864 --> 00:58:00,644 prize. Right? So we're not. And 1597 00:58:01,265 --> 00:58:02,565 and, but also, 1598 00:58:03,025 --> 00:58:06,109 I mean, it's I think, it's an unprecedented 1599 00:58:06,409 --> 00:58:07,769 opportunity. I mean, I don't think, 1600 00:58:08,730 --> 00:58:10,329 yeah, I don't think, anyone, 1601 00:58:10,730 --> 00:58:12,969 could let it slip, honestly. Yeah. No. It's 1602 00:58:12,969 --> 00:58:14,250 a it's a it's a lovely thing. I 1603 00:58:14,250 --> 00:58:16,010 mean, my understanding of it, right, is is 1604 00:58:16,010 --> 00:58:18,909 that it's interesting research that also makes you 1605 00:58:18,969 --> 00:58:19,869 laugh. Right? 1606 00:58:20,224 --> 00:58:21,824 Yes. Yeah. I mean, the the I think 1607 00:58:21,824 --> 00:58:24,085 the line by by Mark Abrahams is, 1608 00:58:24,784 --> 00:58:27,125 research that makes you laugh and then think. 1609 00:58:27,505 --> 00:58:29,985 And, I think the beauty of this, global 1610 00:58:29,985 --> 00:58:30,704 prize is that, 1611 00:58:31,664 --> 00:58:33,605 every year there are there are discoveries 1612 00:58:33,985 --> 00:58:36,320 that, I mean, at first sight, 1613 00:58:37,180 --> 00:58:38,539 they they might look, 1614 00:58:39,260 --> 00:58:41,579 they might not look about science. Right? Because, 1615 00:58:42,140 --> 00:58:44,559 you know, maybe seen by the general public, 1616 00:58:44,619 --> 00:58:45,760 science needs to be 1617 00:58:46,140 --> 00:58:47,280 extremely complex, 1618 00:58:47,660 --> 00:58:49,375 very far from what we are doing in 1619 00:58:49,375 --> 00:58:51,375 our daily life, but, often it's not the 1620 00:58:51,375 --> 00:58:51,875 case. 1621 00:58:52,414 --> 00:58:52,815 And, 1622 00:58:54,974 --> 00:58:57,454 and, and, therefore, this is something that that 1623 00:58:57,454 --> 00:59:00,255 people would find surprising. Therefore, in many cases, 1624 00:59:00,255 --> 00:59:01,889 it can make you laugh. There are, 1625 00:59:02,849 --> 00:59:05,170 but then definitely, it's it's a channel for 1626 00:59:05,170 --> 00:59:07,429 having people thinking about surprising, 1627 00:59:09,409 --> 00:59:11,969 let's say, surprising emergence of science where they 1628 00:59:11,969 --> 00:59:12,789 wouldn't expect. 1629 00:59:13,089 --> 00:59:14,849 I think this is a growing field. I 1630 00:59:14,849 --> 00:59:15,829 mean, the cryodynamics 1631 00:59:16,130 --> 00:59:17,190 is a growing field 1632 00:59:18,224 --> 00:59:18,964 in physics, 1633 00:59:19,824 --> 00:59:21,045 engineering in general. 1634 00:59:22,464 --> 00:59:24,244 It's something that is definitely 1635 00:59:24,545 --> 00:59:25,605 challenging scientifically, 1636 00:59:26,065 --> 00:59:28,644 but also impactful in society as, 1637 00:59:29,505 --> 00:59:32,400 in in places that are very densely populated, 1638 00:59:32,699 --> 00:59:34,539 the Netherlands, UK, and so on and so 1639 00:59:34,539 --> 00:59:36,160 forth. It often happens that 1640 00:59:38,300 --> 00:59:40,940 you the the pressure on public infrastructure like 1641 00:59:40,940 --> 00:59:43,179 the train station grows, by the year, so 1642 00:59:43,179 --> 00:59:44,640 there are more people moving. 1643 00:59:44,974 --> 00:59:45,715 But often, 1644 00:59:46,015 --> 00:59:47,954 it's becoming impossible to extend 1645 00:59:48,894 --> 00:59:49,715 train stations 1646 00:59:50,335 --> 00:59:53,375 to to, cope with increased load. And so 1647 00:59:53,375 --> 00:59:54,594 now the only way 1648 00:59:55,135 --> 00:59:57,315 is is making the environment smarter, 1649 00:59:58,190 --> 01:00:00,030 And this is, one of the reason we 1650 01:00:00,030 --> 01:00:00,849 are doing this. 1651 01:00:01,869 --> 01:00:04,190 I'd like to thank Alessandro and Philip for 1652 01:00:04,190 --> 01:00:05,630 talking to me for this episode of the 1653 01:00:05,630 --> 01:00:07,010 Physics World Stories podcast. 1654 01:00:07,470 --> 01:00:09,470 And, of course, we'll post links to their 1655 01:00:09,470 --> 01:00:11,474 work on the Physics World website, 1656 01:00:12,035 --> 01:00:12,934 physics world.com. 1657 01:00:14,035 --> 01:00:17,175 Next month, we'll be looking at Pele's tears, 1658 01:00:17,315 --> 01:00:19,335 which have more to do with volcanoes 1659 01:00:19,954 --> 01:00:20,695 than football. 1660 01:00:20,994 --> 01:00:23,815 Until then, thank you very much for listening.