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These are the user uploaded subtitles that are being translated: 1 00:00:02,220 --> 00:00:07,099 The natural world is beautiful, but complex. 2 00:00:11,139 --> 00:00:13,718 The skies dance with colour. 3 00:00:17,128 --> 00:00:18,767 Shapes form... 4 00:00:19,707 --> 00:00:21,047 ..and disappear. 5 00:00:25,726 --> 00:00:30,886 But this seemingly infinite complexity is just a shadow of something deeper. 6 00:00:31,326 --> 00:00:33,305 The underlying laws. 7 00:00:33,306 --> 00:00:34,306 The laws of nature. 8 00:00:40,444 --> 00:00:46,324 The world is beautiful to look at, but it's even more beautiful to understand. 9 00:01:17,148 --> 00:01:18,688 A regular day in the snow. 10 00:01:24,077 --> 00:01:27,407 But if you look carefully, there's something deeper. 11 00:01:37,695 --> 00:01:38,695 Everyone... 12 00:01:39,755 --> 00:01:42,015 ..is perfect, pretty much. 13 00:01:43,264 --> 00:01:45,064 Looks like they've been cut out of thin paper. 14 00:01:48,114 --> 00:01:49,114 I got one! 15 00:01:51,993 --> 00:01:54,993 Snowflakes are complex, intricate things. 16 00:01:55,333 --> 00:01:58,912 But they're all different, but there's something similar about them. 17 00:01:59,502 --> 00:02:00,592 They are beautiful. 18 00:02:01,432 --> 00:02:05,331 But there is also, I think, a deeper beauty, and that beauty is in an idea. 19 00:02:06,211 --> 00:02:07,651 The idea is that... 20 00:02:07,876 --> 00:02:12,050 ..all the similarities and difference, the structure of snowflakes, can be 21 00:02:12,051 --> 00:02:15,729 explained using a few simple laws of nature. 22 00:02:16,369 --> 00:02:19,855 And that idea goes to the very heart of science, because 23 00:02:19,856 --> 00:02:23,748 those laws themselves are beautiful and they're universal. 24 00:02:24,443 --> 00:02:29,647 They can explain so many things, from snowflakes to stars. 25 00:02:33,397 --> 00:02:35,006 How do snowflakes form? 26 00:02:36,646 --> 00:02:40,646 Why are they all different, and yet tantalisingly similar? 27 00:02:45,035 --> 00:02:49,014 These are questions that can be asked about any naturally occurring structure. 28 00:02:52,774 --> 00:02:55,293 Why are beehives regular hexagons? 29 00:02:56,053 --> 00:02:57,693 Why do icebergs float? 30 00:02:58,473 --> 00:03:00,093 Why are planets spherical? 31 00:03:00,772 --> 00:03:03,492 And what's this got to do with free diving grannies? 32 00:03:06,972 --> 00:03:12,291 The answers allow us to glimpse the underlying laws of nature that shape them. 33 00:03:17,620 --> 00:03:20,249 This is why, when you look at a snowflake... 34 00:03:22,454 --> 00:03:28,889 ..you're peering beyond the everyday world, at the deep structure of nature itself. 35 00:03:30,928 --> 00:03:32,328 The universe in a snowflake. 36 00:03:40,396 --> 00:03:41,746 Wow, I can see a star. 37 00:03:42,146 --> 00:03:45,626 It really looks like a snow crystal stuck in a bubble. 38 00:03:53,104 --> 00:03:56,644 There's a shape that appears at all scales in the universe. 39 00:04:01,963 --> 00:04:05,722 Seen from space, the Earth is a near-perfect sphere... 40 00:04:09,382 --> 00:04:12,561 ..sculpted by one of the fundamental forces of nature. 41 00:04:19,920 --> 00:04:21,220 Carla, it's your turn now. 42 00:04:24,520 --> 00:04:27,129 I want, I want, I want... 43 00:04:33,478 --> 00:04:34,678 What's possible? 44 00:04:39,057 --> 00:04:41,566 Carla and her friends are about to pit themselves 45 00:04:41,567 --> 00:04:44,378 against the force that's shaped our planet. 46 00:04:46,236 --> 00:04:49,336 Because it's the first time that I've gone to a hole. 47 00:04:50,995 --> 00:04:56,075 And when it's nine o'clock in the morning, everyone is going to jump to the surface 48 00:05:16,902 --> 00:05:18,651 Well, it's very exciting. 49 00:05:19,656 --> 00:05:20,991 You get very nervous. 50 00:05:21,371 --> 00:05:23,230 Very nervous for them, very nervous for everything to 51 00:05:23,231 --> 00:05:25,430 go well, for them not to fall, for them not to get hurt. 52 00:05:27,630 --> 00:05:31,769 What you feel is a beastly emotion, because you get goose bumps and sometimes 53 00:05:31,770 --> 00:05:35,429 you are about to cry before starting to build castles. 54 00:05:45,887 --> 00:05:50,766 These children are going into battle, with gravity. 55 00:06:05,084 --> 00:06:11,923 Towns from across Catalonia have gathered to enter into a fierce competition, 56 00:06:15,003 --> 00:06:16,662 to build a human capital. 57 00:06:16,682 --> 00:06:18,682 A tower as high as possible. 58 00:06:26,841 --> 00:06:29,994 Mum and dad are here with their daughters, Mariona 59 00:06:29,995 --> 00:06:33,041 and Carla, to represent the town of Villafranca. 60 00:06:36,979 --> 00:06:42,238 People of all ages take part, but it's the lightest members of the team, children as 61 00:06:42,239 --> 00:06:45,778 young as five, who ascend daringly to the summit. 62 00:06:49,697 --> 00:06:52,917 There is a lot of nerves, because there are many people. 63 00:06:55,276 --> 00:06:59,276 The family put their trust in the most experienced members of the team, 64 00:06:59,886 --> 00:07:00,885 like David Miret. 65 00:07:02,115 --> 00:07:03,875 Depression of the stage, right? 66 00:07:03,995 --> 00:07:09,154 In addition, the Plaza de Braus has this circular shape, the sound is very loud and 67 00:07:09,304 --> 00:07:10,594 it is a wave, a wave. 68 00:07:15,433 --> 00:07:19,653 From the outside, it may seem that we are a group of people, that we climb up and 69 00:07:19,654 --> 00:07:25,052 that we pile up in an anarchic way, totally, without any rigor. 70 00:07:25,372 --> 00:07:26,572 The first one is the last one! 71 00:07:27,011 --> 00:07:29,591 But no, not all structures have... 72 00:07:34,030 --> 00:07:36,890 David feels the weight of everyone above him. 73 00:07:39,969 --> 00:07:42,629 His gravity pulls them down to the ground. 74 00:07:46,708 --> 00:07:50,768 And he knows the secret to defying gravity is geometry. 75 00:07:51,708 --> 00:07:56,627 They are symmetrical below, they have their own line, they create concentric 76 00:07:56,628 --> 00:07:59,946 lines towards that point, so that the forces go concentrically. 77 00:08:02,506 --> 00:08:08,405 To support David, and eventually the kids, the rest of the town all pushed inwards, 78 00:08:08,980 --> 00:08:13,824 with equal force in all directions, buttressing the tower from all sides. 79 00:08:18,743 --> 00:08:21,783 And this results in the emergence of a symmetrical shape. 80 00:08:22,783 --> 00:08:23,803 A circle. 81 00:08:24,623 --> 00:08:27,222 No other shape gives the tower such strength. 82 00:08:39,340 --> 00:08:41,960 But gravity is unforgiving. 83 00:09:15,205 --> 00:09:19,264 And that's a worry if your child is climbing to the top. 84 00:09:21,504 --> 00:09:24,287 When Carla and Mariona climb up the castle, I have 85 00:09:24,288 --> 00:09:26,643 to follow the castle from the bottom to the top. 86 00:09:30,672 --> 00:09:32,982 I can't be without looking at the castle. 87 00:09:35,657 --> 00:09:41,281 When I climb up the castle, I try not to fall. 88 00:10:53,400 --> 00:10:57,139 It's clear that the force of gravity is unrelenting. 89 00:11:01,778 --> 00:11:06,898 The collapsing towers are shadows of the process that shaped our planet. 90 00:11:11,857 --> 00:11:14,116 These people aren't just falling down. 91 00:11:14,117 --> 00:11:15,517 They're falling towards the ground. 92 00:11:17,376 --> 00:11:20,295 They're falling towards the centre of the Earth. 93 00:11:21,415 --> 00:11:23,455 And the Earth's gravity pulls everything down. 94 00:11:26,605 --> 00:11:28,574 From people to snowflakes. 95 00:11:32,334 --> 00:11:35,373 To the very rock that the Earth is made of. 96 00:11:36,733 --> 00:11:39,593 And this is ultimately why the Earth is spherical. 97 00:11:41,932 --> 00:11:45,352 So why does gravity sculpt things into spheres? 98 00:11:46,052 --> 00:11:49,211 Well, the first thing to say is that it doesn't, necessarily. 99 00:11:52,371 --> 00:11:53,710 If I pick up a snowball... 100 00:11:55,600 --> 00:11:56,600 it's not spherical. 101 00:11:56,890 --> 00:11:58,110 Kind of an irregular shape. 102 00:12:00,229 --> 00:12:02,429 But if I apply pressure to it... 103 00:12:02,859 --> 00:12:06,948 and squash it evenly in all directions... 104 00:12:07,788 --> 00:12:10,268 then I can turn that into a sphere. 105 00:12:10,883 --> 00:12:13,647 And that is what's happening with gravity. 106 00:12:14,407 --> 00:12:19,286 As I start adding mass to it... that gravitational pull becomes bigger. 107 00:12:19,916 --> 00:12:22,586 So I'll get to a point where this snowball... 108 00:12:22,761 --> 00:12:24,266 if I kept adding mass to it... 109 00:12:24,591 --> 00:12:25,925 would be so massive... 110 00:12:26,275 --> 00:12:29,305 that the gravitational pull on its surface would be so strong... 111 00:12:29,555 --> 00:12:34,144 that it would start to squash the material out of which it's made. 112 00:12:34,644 --> 00:12:35,644 In this case, snow. 113 00:12:36,054 --> 00:12:38,323 Or in the case of a planet or moon, the rock. 114 00:12:39,278 --> 00:12:44,682 That pressure exerts on the surface... equally in all directions. 115 00:12:44,902 --> 00:12:48,662 Because gravity works equally in all directions. 116 00:12:50,002 --> 00:12:51,461 Now, you could ask the question... 117 00:12:51,661 --> 00:12:54,821 how much matter do I need for gravity to get strong enough... 118 00:12:55,096 --> 00:12:57,760 to start overcoming the strength of rock... 119 00:12:58,010 --> 00:12:59,500 and sculpting things into spheres? 120 00:13:00,480 --> 00:13:03,900 Well, that minimum size has got a name. 121 00:13:04,000 --> 00:13:04,599 It's a brilliant name. 122 00:13:04,929 --> 00:13:06,129 It's called the potato radius. 123 00:13:06,379 --> 00:13:07,379 And you see why. 124 00:13:07,659 --> 00:13:10,079 Because things that are too small... 125 00:13:10,229 --> 00:13:12,558 for gravity to be strong enough to sculpt them... 126 00:13:12,858 --> 00:13:14,538 look like misshapen potatoes. 127 00:13:18,297 --> 00:13:21,307 The great thing is... you don't even need to imagine it. 128 00:13:22,177 --> 00:13:23,247 You can calculate it. 129 00:13:23,896 --> 00:13:24,896 I did that this morning. 130 00:13:25,126 --> 00:13:28,426 And I got an answer... just roughly between 100 and 200 kilometres. 131 00:13:29,406 --> 00:13:32,325 The brilliant thing... the most beautiful thing... 132 00:13:32,675 --> 00:13:34,065 is if you look up into space... 133 00:13:34,265 --> 00:13:37,044 and look at the moons of Mars and Saturn and Jupiter... 134 00:13:37,045 --> 00:13:39,124 and objects out there in the solar system... 135 00:13:39,474 --> 00:13:41,864 you will find that, roughly speaking... 136 00:13:42,189 --> 00:13:43,383 if their radius is bigger... 137 00:13:43,583 --> 00:13:44,923 than about 200 kilometres... 138 00:13:45,323 --> 00:13:46,363 they're beautiful spheres. 139 00:13:46,803 --> 00:13:49,802 And if the radius is less... than about 200 kilometres... 140 00:13:49,803 --> 00:13:52,242 they look more like misshapen potatoes. 141 00:13:52,822 --> 00:13:54,682 So you can calculate it. 142 00:13:59,396 --> 00:14:00,451 If you're small... 143 00:14:01,021 --> 00:14:02,331 spheres don't come easily. 144 00:14:05,690 --> 00:14:09,209 Even asteroids or moons... don't quite manage it. 145 00:14:09,569 --> 00:14:12,689 A potato shape... might be as close as you can get. 146 00:14:17,938 --> 00:14:21,458 But when you're the size of a planet... spheres come naturally. 147 00:14:29,856 --> 00:14:34,236 Four and a half billion years ago... rocks circling the Sun... 148 00:14:34,237 --> 00:14:37,975 began sticking together... until they had sufficient mass... 149 00:14:37,976 --> 00:14:42,494 for gravity to really get to work... turning potato shapes... 150 00:14:42,495 --> 00:14:46,574 into one very important sphere... suspended in space. 151 00:14:53,063 --> 00:14:56,702 A universal law... sculpted the familiar... 152 00:14:56,992 --> 00:14:59,803 elegant, symmetrical shape... of our planet. 153 00:15:06,861 --> 00:15:12,340 But closer to the surface... it's littered... with endless shapes and forms. 154 00:15:16,559 --> 00:15:20,478 And in every one of these... naturally occurring structures... 155 00:15:20,928 --> 00:15:24,858 there are simple underlying laws... waiting to be glimpsed. 156 00:15:30,607 --> 00:15:32,017 Here in the Himalayas... 157 00:15:32,347 --> 00:15:36,426 there's a shape... that's a shadow... of a fundamental mathematical law. 158 00:15:39,925 --> 00:15:42,525 It's guarded by the Himalayan honey bee... 159 00:15:45,795 --> 00:15:49,195 the largest species of honey bee... on the planet. 160 00:15:50,914 --> 00:15:55,273 And collecting honey... from under their watchful... compound eyes... 161 00:15:55,523 --> 00:15:58,434 is one of the most dangerous jobs... you could imagine. 162 00:16:13,650 --> 00:16:14,650 But that's nothing... 163 00:16:15,430 --> 00:16:17,990 for the young villagers. 164 00:16:19,209 --> 00:16:22,010 Today... it's the first time... for one of the young villagers. 165 00:16:22,524 --> 00:16:24,609 Min and his nephew Herah... 166 00:16:24,809 --> 00:16:27,489 will be the ones leading the hunt... for the precious honey. 167 00:16:27,988 --> 00:16:30,608 It's prized... for its medicinal properties... 168 00:16:30,758 --> 00:16:32,327 and sells for a high price. 169 00:16:37,757 --> 00:16:38,756 The local culture... 170 00:16:38,931 --> 00:16:40,846 protects the whole place... by its magic. 171 00:16:41,496 --> 00:16:42,496 Be careful... 172 00:16:43,766 --> 00:16:46,245 when you are walking on... these roads... 173 00:16:47,305 --> 00:16:50,106 Hidden beneath the seething mass of bodies sits 174 00:16:50,107 --> 00:16:53,465 a network of exquisitely engineered hexagons. 175 00:16:57,833 --> 00:17:01,560 The bees appear to be master builders, performing 176 00:17:01,561 --> 00:17:04,692 structural calculations with architectural precision. 177 00:17:19,100 --> 00:17:23,035 The bees benefit from a hidden mathematical law that 178 00:17:23,036 --> 00:17:26,029 explains why they build hexagons to store their honey. 179 00:17:26,884 --> 00:17:29,455 And twice a year, the Gurung people head into 180 00:17:29,555 --> 00:17:32,868 the mountains to exploit the bees' secret. 181 00:17:36,458 --> 00:17:42,078 Because it's Hira's first time, this trip will be particularly challenging. 182 00:17:50,715 --> 00:17:53,195 If you want to eat honey, you have to dig a hole. 183 00:17:54,415 --> 00:17:57,134 This is the new honey that I learned from Niravani. 184 00:17:57,644 --> 00:17:58,874 This is Hira's honey. 185 00:17:59,544 --> 00:18:01,694 I don't know if it will work or not. 186 00:18:04,613 --> 00:18:06,133 Uncle, let's start from the beginning. 187 00:18:06,873 --> 00:18:07,873 Hey, 188 00:18:17,311 --> 00:18:18,507 let's start from the beginning. 189 00:18:18,531 --> 00:18:19,531 Hey, take it. 190 00:18:26,120 --> 00:18:31,120 The bees make their hives as inaccessible as possible to protect them from predators. 191 00:19:02,614 --> 00:19:08,126 The hives the bees are defending contain a vivid, 192 00:19:08,127 --> 00:19:11,733 visible solution to a deep mathematical problem. 193 00:19:12,483 --> 00:19:13,653 And a very practical one. 194 00:19:15,517 --> 00:19:19,912 They need to store honey to sustain their colony through the long winter months. 195 00:19:21,411 --> 00:19:22,911 They build their hives out of wax. 196 00:19:25,051 --> 00:19:28,574 But for every gram of wax a bee produces, it will 197 00:19:28,624 --> 00:19:31,680 have to consume more than six grams of honey. 198 00:19:34,779 --> 00:19:39,649 So they benefit from building efficiently, using as little wax as possible. 199 00:19:58,756 --> 00:20:01,575 In the beginning, I was a little scared of primers. 200 00:20:26,151 --> 00:20:27,151 Each 201 00:20:34,630 --> 00:20:37,410 sting is like a hypodermic needle. 202 00:20:38,829 --> 00:20:40,889 After the bees sting, they die. 203 00:20:44,049 --> 00:20:45,588 The ultimate sacrifice. 204 00:20:46,068 --> 00:20:47,508 To guard the hexagons. 205 00:20:47,863 --> 00:20:49,328 And the honey they hold. 206 00:21:02,056 --> 00:21:03,836 At first, I was a little scared. 207 00:21:05,075 --> 00:21:09,475 But when I got to the bank, I realized that it's okay. 208 00:21:09,935 --> 00:21:11,194 I have my own mind. 209 00:21:47,329 --> 00:21:53,168 Before I started learning, I was a little scared. 210 00:21:53,848 --> 00:21:54,848 I was afraid. 211 00:21:55,008 --> 00:21:56,008 Maybe. 212 00:21:56,827 --> 00:21:58,627 But it is a good thing, always. 213 00:21:58,628 --> 00:22:00,987 When I see the honey, I start working on it. 214 00:22:10,005 --> 00:22:14,385 For Hiro, this is all about keeping the Gurung tradition of honey hunting alive. 215 00:22:17,224 --> 00:22:20,644 When the hexagon is at the heart of it all. 216 00:22:21,344 --> 00:22:29,142 I just want the honey to keep on growing. 217 00:22:41,501 --> 00:22:43,470 How do bees build hexagonal honeycombs? 218 00:22:46,115 --> 00:22:48,689 Well, that is, in fact, a very good question. 219 00:22:48,829 --> 00:22:50,349 It's actually a mathematical question. 220 00:22:53,354 --> 00:22:57,747 The problem is, how do I divide up a volume into 221 00:22:57,748 --> 00:23:01,487 shapes of equal size using the minimum amount of stuff? 222 00:23:02,847 --> 00:23:04,787 Now, why does that matter to a bee? 223 00:23:05,317 --> 00:23:09,586 Because that stuff is wax, and wax is extremely valuable to the bees. 224 00:23:09,786 --> 00:23:13,066 So, what shape should it be? 225 00:23:13,656 --> 00:23:16,865 Should it be squares, or should it be triangles? 226 00:23:17,295 --> 00:23:20,065 You can see it can't be circles, because circles, when you pack them 227 00:23:20,066 --> 00:23:22,364 together, leave gaps, so they're not very efficient. 228 00:23:23,264 --> 00:23:26,744 Or could it be that hexagons are the most efficient? 229 00:23:27,703 --> 00:23:32,983 Well, that is actually a simple-sounding question with a very complicated answer. 230 00:23:33,083 --> 00:23:34,982 It's one of the oldest questions in mathematics. 231 00:23:35,952 --> 00:23:36,992 It's got a name, actually. 232 00:23:37,212 --> 00:23:38,692 It's called the honeycomb conjecture. 233 00:23:39,042 --> 00:23:42,081 Mathematicians say, that the bees have worked on it for thousands and thousands 234 00:23:42,082 --> 00:23:47,680 of years, and it's only recently that the honeycomb conjecture was proved. 235 00:23:49,030 --> 00:23:50,030 Here's one of the proofs. 236 00:23:51,340 --> 00:23:52,480 Huge paper. 237 00:23:53,599 --> 00:23:56,499 Pages and pages of complex mathematics. 238 00:23:57,774 --> 00:24:01,318 And it turns out that the hexagon is the most efficient shape. 239 00:24:02,083 --> 00:24:07,037 The bees knew what human mathematicians didn't know for thousands of years. 240 00:24:07,592 --> 00:24:09,557 Actually, I'm using know in quite a way. 241 00:24:09,558 --> 00:24:10,793 There's quite a loose sense there. 242 00:24:10,817 --> 00:24:13,623 There's still a great deal of debate amongst 243 00:24:13,624 --> 00:24:16,497 biologists as to how the bees actually do it. 244 00:24:17,046 --> 00:24:23,375 Do they build hexagons from scratch using some kind of instinctive behaviour? 245 00:24:24,185 --> 00:24:28,494 Or do they in fact build a simpler shape, perhaps circles, and then because the wax 246 00:24:28,644 --> 00:24:31,865 heats up, it can deform, and the laws of physics 247 00:24:31,866 --> 00:24:34,573 themselves change the circles into hexagons? 248 00:24:35,083 --> 00:24:36,413 That's still not agreed upon. 249 00:24:36,414 --> 00:24:40,361 But what is agreed upon by the mathematicians and 250 00:24:40,362 --> 00:24:43,412 the bees is the hexagon is the most efficient shape. 251 00:24:44,062 --> 00:24:45,741 That just shows you it's a beautiful thing. 252 00:24:46,021 --> 00:24:48,931 Mathematics is the universal language. 253 00:24:49,291 --> 00:24:54,230 And when you look at a perfect honeycomb, you see a shadow of that language, 254 00:24:54,430 --> 00:24:58,569 of mathematics made real by bees. 255 00:25:05,178 --> 00:25:07,918 Perfect shapes reveal simple laws. 256 00:25:13,437 --> 00:25:17,077 Whether it's spherical planets sculpted by gravity, 257 00:25:21,126 --> 00:25:23,725 pulling us to the centre of the Earth... 258 00:25:27,845 --> 00:25:32,764 ..or the mathematically refined efficiency of hexagonal honeycombs... 259 00:25:36,324 --> 00:25:39,563 ..simple laws underpin the shapes we can see. 260 00:25:40,668 --> 00:25:42,123 And they're universal. 261 00:25:45,502 --> 00:25:51,001 But the action of these simple laws seems at odds with the complex shapes of life. 262 00:26:04,099 --> 00:26:09,738 These shallow springs are home to one of nature's seemingly less elegant shapes... 263 00:26:18,507 --> 00:26:19,507 ..the manatee. 264 00:26:20,877 --> 00:26:24,826 Like all marine animals, they're free from the effects of gravity. 265 00:26:25,641 --> 00:26:27,946 No need for strong bones to support their weight. 266 00:26:30,105 --> 00:26:32,865 But they don't have complete freedom from the laws of physics. 267 00:26:33,410 --> 00:26:36,164 Several manatees are hunting some mothers and cats. 268 00:26:36,304 --> 00:26:37,304 There they are. 269 00:26:38,024 --> 00:26:39,024 It's winter. 270 00:26:39,184 --> 00:26:43,063 And if the water temperature here drops below 20 degrees... 271 00:26:43,064 --> 00:26:44,943 Do you think the temperature's Friday morning? 272 00:26:45,523 --> 00:26:47,643 ..for the manatee, it's deadly. 273 00:26:48,607 --> 00:26:51,922 Very dangerous in terms of warmer and hotter environments. 274 00:26:53,762 --> 00:26:56,961 Manatees, like this female, are vegetarians. 275 00:26:59,311 --> 00:27:02,660 Basically, she's a ten-foot-long aquatic cow with no legs. 276 00:27:03,650 --> 00:27:05,962 To stay warm, she has to consume up to 50 277 00:27:05,963 --> 00:27:09,780 kilograms of leaves and sea grass every day. 278 00:27:10,789 --> 00:27:13,119 And the females here are eating for others, too. 279 00:27:14,388 --> 00:27:16,498 This one is suckling two young calves. 280 00:27:16,998 --> 00:27:19,538 And the weather is only getting colder. 281 00:27:22,337 --> 00:27:23,337 Lemon? 282 00:27:24,747 --> 00:27:25,747 On the roof? 283 00:27:26,337 --> 00:27:27,336 No. 284 00:27:29,266 --> 00:27:30,706 Looking good. 285 00:27:36,085 --> 00:27:37,085 There's Doug. 286 00:27:37,535 --> 00:27:38,645 Doug likes it up here now. 287 00:27:39,790 --> 00:27:42,347 Researcher Wayne Hartley is doing this morning's 288 00:27:42,348 --> 00:27:45,345 head count, part of the manatee census. 289 00:27:49,483 --> 00:27:52,023 It's a special thing to come to work. 290 00:27:52,763 --> 00:27:56,762 You come down in the morning and it's quiet. 291 00:27:57,832 --> 00:27:59,661 The steam's coming off the water. 292 00:28:04,791 --> 00:28:07,150 You can hear the manatees out there, breathing. 293 00:28:07,520 --> 00:28:08,690 It's just whoosh. 294 00:28:11,340 --> 00:28:12,989 And they are so peaceful. 295 00:28:13,189 --> 00:28:14,509 They are so calm. 296 00:28:16,669 --> 00:28:19,918 Just watching manatees, it's got to be good for your 297 00:28:19,919 --> 00:28:22,888 blood pressure or anything else that may ail you. 298 00:28:33,476 --> 00:28:37,576 Biologist Amy Tegg is working with Wayne to do a health check on the families. 299 00:28:40,055 --> 00:28:43,075 Well, he's just sort of hanging around, checking things out. 300 00:28:43,076 --> 00:28:46,954 Manatees are very docile, gentle creatures. 301 00:28:48,014 --> 00:28:49,174 But they are very curious. 302 00:28:49,944 --> 00:28:53,213 Anything new in their environment, they often like to come check out. 303 00:28:53,823 --> 00:28:56,633 So he's probably just checking me out. 304 00:28:57,433 --> 00:28:59,172 Yeah, he's just chewing on my flipper. 305 00:29:00,742 --> 00:29:02,472 It's got 23.5 degrees Celsius. 306 00:29:03,852 --> 00:29:08,051 Manatee families are drawn in from colder waters because this is a hot spring. 307 00:29:09,341 --> 00:29:11,130 And some make it just in time. 308 00:29:11,131 --> 00:29:14,110 He is severely cold-stressed. 309 00:29:16,160 --> 00:29:17,809 With the cold stress, they don't eat. 310 00:29:19,429 --> 00:29:21,029 Their immune system shuts down. 311 00:29:22,029 --> 00:29:24,768 They're here to keep themselves alive in the winter. 312 00:29:24,948 --> 00:29:28,288 They really require warm water. 313 00:29:32,597 --> 00:29:36,976 It might look like these animals keep warm using blubber, like seals. 314 00:29:38,076 --> 00:29:39,396 But they're not fat. 315 00:29:40,266 --> 00:29:41,266 They're round. 316 00:29:42,471 --> 00:29:46,535 In terms of pure physics, the best way to stay warm is to be a sphere. 317 00:29:51,154 --> 00:29:55,474 It has the smallest surface area-to-volume ratio of any shape. 318 00:29:56,174 --> 00:29:58,773 Less area for heat to escape from. 319 00:30:00,173 --> 00:30:03,334 A beautiful example of a naturally occurring 320 00:30:03,335 --> 00:30:06,432 shape, reflecting a deeper mathematical law. 321 00:30:07,752 --> 00:30:11,131 The manatee could well be the most spherical mammal on Earth. 322 00:30:11,971 --> 00:30:13,551 What a wonderful thing to be. 323 00:30:19,540 --> 00:30:20,140 The manatee is a manatee. 324 00:30:20,141 --> 00:30:21,221 Sorry, their breath stinks. 325 00:30:22,379 --> 00:30:25,119 To me, it smells like the inside of a hot truck tire. 326 00:30:30,358 --> 00:30:32,778 But of course, they're not perfect spheres. 327 00:30:34,673 --> 00:30:38,377 There are many other competing factors that determine their shape. 328 00:30:39,017 --> 00:30:45,276 Like all animals, they have to live, breathe, eat... and move. 329 00:30:48,855 --> 00:30:50,835 The manatee's natural habitat is shrinking. 330 00:30:51,665 --> 00:30:53,755 And they need to find warmth elsewhere. 331 00:30:57,774 --> 00:31:01,993 This power station helps provide energy for around nine million people. 332 00:31:02,833 --> 00:31:06,413 And in the process, warms the water that keeps over 333 00:31:06,414 --> 00:31:09,212 half of Florida's manatees alive through the winter. 334 00:31:13,642 --> 00:31:20,121 The same families that Wayne and Amy study can end up here, over 300 kilometres away. 335 00:31:21,340 --> 00:31:24,880 Where their mothers and calves can hold on to as much heat as possible. 336 00:31:26,140 --> 00:31:27,879 Because of their round bodies. 337 00:31:30,519 --> 00:31:35,738 To a physicist, the perfect shape for a manatee would be a symmetrical sphere. 338 00:31:36,943 --> 00:31:38,558 But biology complicates things. 339 00:31:40,617 --> 00:31:44,817 Manatees can't just bob around waiting for food or warmth to come to them. 340 00:31:45,997 --> 00:31:48,696 They need fins and a tail to move around. 341 00:31:50,656 --> 00:31:53,975 Whether that's to a hot spring, or to a power station. 342 00:32:05,984 --> 00:32:10,363 The forces of nature sculpt and restrict the shapes of all things. 343 00:32:10,663 --> 00:32:14,982 The inanimate, like pebbles or rocks or cliffs. 344 00:32:15,662 --> 00:32:16,942 Or living things. 345 00:32:19,601 --> 00:32:23,601 But of course, basic physics is not the only force shaping life. 346 00:32:28,140 --> 00:32:33,499 Evolution by natural selection moulds living things over time in response to 347 00:32:33,500 --> 00:32:36,899 their environment and their interaction with other life forms. 348 00:32:41,138 --> 00:32:43,838 And it's had billions of years to do it. 349 00:32:46,527 --> 00:32:48,577 So, you can't understand the shapes. 350 00:32:49,027 --> 00:32:50,113 The shapes of living things. 351 00:32:50,137 --> 00:32:52,696 Without understanding their evolutionary history. 352 00:33:16,593 --> 00:33:17,592 We're 353 00:33:25,481 --> 00:33:28,021 all the product of our experiences. 354 00:33:28,501 --> 00:33:29,861 Our history. 355 00:33:30,021 --> 00:33:31,120 Our culture. 356 00:33:31,770 --> 00:33:34,340 Our lives make an indelible impression. 357 00:33:35,700 --> 00:33:36,740 And make us all different. 358 00:33:42,389 --> 00:33:44,148 But we are also all similar. 359 00:33:45,448 --> 00:33:47,088 Not just to each other as human beings. 360 00:33:47,568 --> 00:33:50,127 But to countless other animals on Earth. 361 00:33:51,477 --> 00:33:53,007 We are obviously related. 362 00:33:57,816 --> 00:33:58,816 Most obviously. 363 00:33:59,491 --> 00:34:01,686 Through the symmetry of our bodies. 364 00:34:16,903 --> 00:34:17,903 I'm Kim Sun-duk. 365 00:34:18,628 --> 00:34:19,628 I'm 73. 366 00:34:23,022 --> 00:34:28,162 Mrs. Choi and Ms. Kim, the Henyo, are women of the sea. 367 00:34:28,362 --> 00:34:30,901 They've grown up collecting seafood along the shores. 368 00:34:32,641 --> 00:34:34,041 But they still do. 369 00:34:47,089 --> 00:34:49,648 The haenyeo are part of a dying tradition. 370 00:34:50,188 --> 00:34:52,528 Not many youngsters are interested in one. 371 00:34:53,988 --> 00:34:57,667 It's hard work, especially if you're in your seventies. 372 00:35:26,133 --> 00:35:29,692 Right now, the women are catching conch, or sea snails. 373 00:35:33,112 --> 00:35:37,111 It's a crucial time of year, when they have a chance to make the most money. 374 00:35:49,969 --> 00:35:54,788 The tradition of freediving for food is part of these women's cultural history, 375 00:35:55,223 --> 00:36:01,287 but the details of the human form itself, in particular its symmetry that allows 376 00:36:01,288 --> 00:36:05,847 them to dive, swim and hunt, is part of their evolutionary history. 377 00:36:18,485 --> 00:36:20,844 For Mrs Choi, and Miss Kim, this is all about the search for food. 378 00:36:20,864 --> 00:36:27,563 Calming sensation 379 00:36:45,370 --> 00:36:49,510 For Mrs Choi and Miss Kim, this is all about the search for food. 380 00:36:53,619 --> 00:36:57,219 And that's where the symmetrical structure of their bodies comes in. 381 00:36:57,794 --> 00:37:02,838 A blueprint that started out here in the oceans, hundreds of millions of years ago. 382 00:37:06,847 --> 00:37:09,327 Very few animals have steered clear of it. 383 00:37:32,973 --> 00:37:36,693 Life is, and always has been, a competition. 384 00:37:37,467 --> 00:37:40,524 In a free-floating world, life grew to adopt 385 00:37:40,525 --> 00:37:43,852 different types of symmetry to get what it needed. 386 00:37:46,411 --> 00:37:50,110 Some animals became round, or radially symmetric, 387 00:37:50,111 --> 00:37:53,630 organising their sensory organs around a central axis. 388 00:37:54,870 --> 00:37:59,069 Rather than chasing down food, they waited for food to come to them. 389 00:38:01,169 --> 00:38:06,128 But in order to really go after prey, you need to leave that strategy behind. 390 00:38:09,657 --> 00:38:12,097 You need to be divided down the middle. 391 00:38:13,017 --> 00:38:14,257 That gives you two sides. 392 00:38:15,257 --> 00:38:16,256 A bilateral symmetry. 393 00:38:16,576 --> 00:38:19,136 Basically, you have a left and a right. 394 00:38:22,845 --> 00:38:27,525 And you can build on this plan, with arms to grab and search. 395 00:38:27,745 --> 00:38:29,724 And a head, and a tail. 396 00:38:31,144 --> 00:38:36,143 All this means you can orientate yourself, and really target your prey. 397 00:38:44,322 --> 00:38:49,201 This body plan has been selected for over hundreds of millions of years. 398 00:38:50,061 --> 00:38:52,241 It confers a survival advantage. 399 00:38:53,641 --> 00:38:58,460 And it turns out that all animals with brains are bilaterally symmetrical. 400 00:39:03,819 --> 00:39:06,580 Bilateral symmetry provided the agility that 401 00:39:06,592 --> 00:39:09,118 drove a spiral of cunning and ingenuity. 402 00:39:09,119 --> 00:39:10,624 And the ability to catch fast predators. 403 00:39:10,648 --> 00:39:12,398 And skittish, speedy prey. 404 00:39:13,738 --> 00:39:15,937 It's been a long time since we've had such strong waves. 405 00:39:23,916 --> 00:39:25,376 I caught a lot today. 406 00:39:25,736 --> 00:39:29,575 When I catch a lot, I feel good. 407 00:39:29,835 --> 00:39:30,871 I feel like I'm going to fly. 408 00:39:30,895 --> 00:39:33,295 But if I can't catch this, I feel bad. 409 00:39:33,754 --> 00:39:34,890 I feel like I'm going to die. 410 00:39:34,914 --> 00:39:35,914 I'm going to die. 411 00:39:36,194 --> 00:39:42,903 I'm going to die. 412 00:39:42,904 --> 00:39:43,123 I'm going to die. 413 00:39:43,124 --> 00:39:46,762 The beautiful symmetry of the human body, which we all take for granted, 414 00:39:48,022 --> 00:39:51,342 is the product of a sweeping, majestic story. 415 00:39:53,201 --> 00:39:56,201 Stretching back to some of the earliest life on Earth. 416 00:40:06,229 --> 00:40:11,669 So we can understand the symmetry of organisms by understanding their history. 417 00:40:14,268 --> 00:40:19,607 You're essentially seeing the results of evolution by natural selection over 418 00:40:19,608 --> 00:40:23,427 hundreds of millions, even billions of years. 419 00:40:27,496 --> 00:40:32,565 But how do you understand the structure and symmetry of a snowflake? 420 00:40:33,175 --> 00:40:35,265 There's no natural selection here. 421 00:40:35,845 --> 00:40:39,584 There's no DNA to record and reproduce information. 422 00:40:39,585 --> 00:40:45,503 These things arise spontaneously from basic laws of physics. 423 00:40:47,463 --> 00:40:48,463 Bingo! 424 00:40:48,643 --> 00:40:49,643 Bingo! 425 00:40:50,478 --> 00:40:51,478 Oh, bingo! 426 00:40:52,007 --> 00:40:55,142 The intricate beauty of a snowflake is at first 427 00:40:55,143 --> 00:40:58,941 sight baffling, given the simplicity of their story. 428 00:40:59,676 --> 00:41:02,361 But in fact, it's a gift. 429 00:41:02,751 --> 00:41:05,040 A gift of almost nothing. 430 00:41:05,895 --> 00:41:10,120 One frozen moment that can reveal how the underlying story, the underlying laws of 431 00:41:10,121 --> 00:41:13,799 nature, can lead to seemingly infinite complexity. 432 00:41:19,288 --> 00:41:24,957 Because snowflakes form in minutes and are made out of a single ingredient with 433 00:41:24,958 --> 00:41:28,413 strange properties that give rise to a vast array of 434 00:41:28,414 --> 00:41:33,616 naturally occurring forms of all shapes, sizes and behaviours. 435 00:41:37,635 --> 00:41:38,635 Ice. 436 00:41:46,824 --> 00:41:50,303 涄 You know, it's so mystical when you leave in a morning in the fog. 437 00:41:51,503 --> 00:41:53,103 You're just looking around. 438 00:41:55,163 --> 00:41:58,102 And then you see these shapes that come out of the fog. 439 00:42:07,991 --> 00:42:10,150 They're big, big heavy objects. 440 00:42:10,330 --> 00:42:14,570 Far bigger than anything we've created floating on the sea. 441 00:42:34,837 --> 00:42:37,827 We've got to remember it was an iceberg that sailed 442 00:42:37,867 --> 00:42:40,556 past Newfoundland, which ended up sinking the Titanic. 443 00:42:44,285 --> 00:42:46,395 Doug Allen is here because it's iceberg season. 444 00:42:49,249 --> 00:42:51,094 He's part of a scientific expedition. 445 00:42:51,734 --> 00:42:56,653 Every summer, thousands of icebergs float south from the Arctic into the shipping 446 00:42:56,654 --> 00:42:59,553 lanes and oil fields off the coast of Newfoundland. 447 00:43:02,152 --> 00:43:07,612 This team are here to help protect those multi-billion-dollar industries by trying 448 00:43:07,613 --> 00:43:10,431 to understand more about where the icebergs are heading. 449 00:43:11,991 --> 00:43:15,050 The man leading the expedition is Neil Riggs. 450 00:43:15,660 --> 00:43:19,610 So you put it back in the water again, OK, and if we lose, well, then we take it 451 00:43:19,611 --> 00:43:22,809 in, we secure it, and if that goes nowhere, we go home. 452 00:43:26,309 --> 00:43:28,628 The big problem with icebergs is simple. 453 00:43:29,268 --> 00:43:30,268 They float. 454 00:43:37,987 --> 00:43:41,986 Iceberg ice reflects radar 69 times less effectively 455 00:43:41,987 --> 00:43:44,587 than a ship of the same cross-sectional area. 456 00:43:47,025 --> 00:43:54,324 So you could be sailing along and doing very good seamanship, looking at your 457 00:43:54,325 --> 00:43:58,444 radar, and there's the thing all of a sudden, and you're upon it, and it's still 458 00:43:58,445 --> 00:44:00,443 a massive piece of ice relative to your ship. 459 00:44:01,173 --> 00:44:02,613 So it could make a nice little hole. 460 00:44:04,943 --> 00:44:09,142 The team will have to understand the influence of a large number of variables 461 00:44:09,143 --> 00:44:14,001 if they are to distinguish between harmless icebergs and dangerous ones. 462 00:44:14,841 --> 00:44:16,581 It's a complicated jigsaw. 463 00:44:16,641 --> 00:44:19,400 It's a little bit, you could think of it as a crime scene where you have the 464 00:44:19,401 --> 00:44:21,947 forensic people go in and they pick up little bits 465 00:44:21,948 --> 00:44:24,541 of clues and together you make a bigger picture. 466 00:44:25,600 --> 00:44:30,159 What I'm doing is just adding my little piece to the overall picture and hopefully 467 00:44:30,160 --> 00:44:33,818 helping their mathematical models to be more real. 468 00:44:36,273 --> 00:44:38,338 Doug is a specialist cold water diver. 469 00:44:39,342 --> 00:44:42,777 It's his job to photograph the underside of the icebergs. 470 00:44:43,457 --> 00:44:46,276 Go on up to some of those smaller pieces, please. 471 00:44:46,277 --> 00:44:46,596 Okay. 472 00:44:46,736 --> 00:44:47,196 Okay. 473 00:44:47,656 --> 00:44:50,976 Yes, Captain Manning, are we okay to put the divers on? 474 00:44:50,977 --> 00:44:52,755 Rick Stanley is looking after safety. 475 00:44:58,954 --> 00:45:00,274 Who knows what's going to happen? 476 00:45:00,344 --> 00:45:05,563 There's so much pressure in this ice that it blows, it explodes. 477 00:45:05,564 --> 00:45:10,583 But there's pressure in there that can blow a piece of iceberg off the ice, 478 00:45:11,142 --> 00:45:12,722 probably 15 or 20 feet. 479 00:45:19,741 --> 00:45:23,601 And we were just pottering around and suddenly, with no warning at all, 480 00:45:23,846 --> 00:45:25,712 the whole thing split in half and it was 481 00:45:25,713 --> 00:45:29,161 almost like it was all falling into each other. 482 00:45:36,719 --> 00:45:38,118 This might be a bit unstable. 483 00:45:38,538 --> 00:45:40,078 This is a huge bird. 484 00:45:41,118 --> 00:45:44,057 I'd rather dive around one that wasn't falling apart. 485 00:45:44,457 --> 00:45:45,457 Yeah. 486 00:45:48,797 --> 00:45:53,776 These giant frozen mountains are born from the most innocent beginnings. 487 00:45:59,935 --> 00:46:00,935 Snowflakes. 488 00:46:03,114 --> 00:46:06,751 Over thousands of years, they're compressed to 489 00:46:06,752 --> 00:46:10,633 form glaciers, but then break off to form icebergs. 490 00:46:11,553 --> 00:46:14,533 An average one weighs 200,000 tonnes. 491 00:46:16,672 --> 00:46:22,352 And that, give or take, is around 100 trillion snowflakes that form the 492 00:46:22,353 --> 00:46:25,817 structures that the expedition is trying to model, using a 493 00:46:25,818 --> 00:46:29,930 combination of sonar robots and Doug's first-hand observations. 494 00:46:32,430 --> 00:46:34,490 I basically have a good look at one side of 495 00:46:34,491 --> 00:46:37,550 the bed between the surface and 30 metres. 496 00:46:37,869 --> 00:46:40,515 Tell them what I saw and it will mean that they 497 00:46:40,516 --> 00:46:42,828 can interpret the sonar data that comes back. 498 00:46:42,968 --> 00:46:45,548 They'll get a better idea of it if I've seen it for myself. 499 00:47:14,883 --> 00:47:18,163 It's quite eerie going down the side of the iceberg. 500 00:47:19,763 --> 00:47:24,382 You're going down into the darkness, into the blue, into the green. 501 00:47:30,571 --> 00:47:35,550 And very occasionally there'll be this really loud thump, just like someone had 502 00:47:35,551 --> 00:47:38,890 hit you with the flat of their hand in the centre of your chest. 503 00:47:40,789 --> 00:47:43,209 Where the iceberg is banging on the bottom. 504 00:47:51,738 --> 00:47:54,977 You really don't want to go too far down because there is 505 00:47:54,978 --> 00:47:57,537 a real danger of being squished by the iceberg underneath. 506 00:48:03,426 --> 00:48:05,716 Well, you always worry when divers are in the water. 507 00:48:06,151 --> 00:48:10,061 But iceberg diving, there's even more of that anticipation 508 00:48:10,062 --> 00:48:13,994 and excitement that goes on in the lower part of your belly. 509 00:48:22,913 --> 00:48:26,212 So you swim in and you begin to see the details. 510 00:48:26,332 --> 00:48:30,472 You begin to realise that this is not a flat boat. 511 00:48:30,492 --> 00:48:32,212 This is a wall of ice going into the depths. 512 00:48:32,571 --> 00:48:37,111 This has tiny little dimples on it which almost looks like a giant golf ball. 513 00:48:44,170 --> 00:48:48,809 These features are added to the models to understand how they affect the way the 514 00:48:48,810 --> 00:48:53,348 icebergs float and travel over long distances and into the shipping lanes. 515 00:48:55,768 --> 00:48:59,127 It's good to contribute to science at a basic level like this. 516 00:48:59,452 --> 00:49:02,479 When the science is still developing, to come in, take some 517 00:49:02,480 --> 00:49:04,787 shots, which help the scientists, that's really useful. 518 00:49:10,156 --> 00:49:16,236 For all their unpredictability, there is regularity in the behaviour of icebergs. 519 00:49:18,934 --> 00:49:22,834 If you look carefully and ask the right questions. 520 00:49:23,534 --> 00:49:25,433 Which is what science is all about. 521 00:49:32,642 --> 00:49:37,171 And the simplest question of all is about the most obvious part of their behaviour. 522 00:49:40,996 --> 00:49:41,996 Why does ice float? 523 00:49:44,510 --> 00:49:45,630 That's not a naive question. 524 00:49:46,220 --> 00:49:50,030 Because no other commonly occurring solid floats on its own liquid. 525 00:49:52,619 --> 00:49:56,189 The answer lies in the structure of the water molecule itself. 526 00:49:58,168 --> 00:49:59,308 Think of what a molecule is. 527 00:49:59,448 --> 00:50:01,508 Take a water molecule for example. 528 00:50:02,228 --> 00:50:05,567 It's two hydrogen atoms stuck to an oxygen atom. 529 00:50:06,347 --> 00:50:12,706 That's two hydrogen nuclei which have positive electric charge sticking to an 530 00:50:12,707 --> 00:50:15,606 oxygen nucleus which has a positive electric charge. 531 00:50:16,345 --> 00:50:19,345 And they're surrounded by negatively charged electrons. 532 00:50:19,740 --> 00:50:21,785 That's what sticks the atoms together. 533 00:50:22,385 --> 00:50:27,624 The negatively charged electrons tend to cluster around the oxygen nucleus, 534 00:50:28,364 --> 00:50:34,363 leaving those two legs of hydrogen slightly positively charged. 535 00:50:35,133 --> 00:50:39,842 That means that those positive charges can attract other There are other negatively 536 00:50:40,142 --> 00:50:42,501 charged ends of other water molecules. 537 00:50:42,941 --> 00:50:47,901 So an oxygen can come and orientate itself and bond to that leg. 538 00:50:48,790 --> 00:50:52,560 On the other side, another oxygen from another water molecule will be attracted 539 00:50:52,660 --> 00:50:55,539 to the positive charge and bond to that leg. 540 00:50:55,979 --> 00:50:58,759 On the top, you get a hydrogenate bonding to that leg. 541 00:50:59,079 --> 00:51:02,507 So you can see you build up a structure, an open 542 00:51:02,557 --> 00:51:06,418 crystal structure, a shape which is actually hexagonal. 543 00:51:07,093 --> 00:51:12,057 And it's that property, that open structure, which is a reflection of the 544 00:51:12,058 --> 00:51:17,071 underlying structure of the water molecule itself, that 545 00:51:17,072 --> 00:51:21,115 leads to the solid ice being less dense than the liquid. 546 00:51:21,515 --> 00:51:27,954 And that is why ice cubes and icebergs float on liquid water. 547 00:51:31,774 --> 00:51:35,392 The hexagonal structure of ice is a shadow of the 548 00:51:35,393 --> 00:51:38,174 forces of nature that hold molecules together. 549 00:51:43,312 --> 00:51:46,472 Forces that shape every molecule of water. 550 00:51:48,081 --> 00:51:52,091 And that create a six-fold symmetry of snowflakes. 551 00:51:57,130 --> 00:51:58,820 You can tell they're all the same thing. 552 00:51:59,780 --> 00:52:00,879 They're all six-sided. 553 00:52:02,539 --> 00:52:07,118 And yet you can also see, just by eye, that everyone is different. 554 00:52:07,258 --> 00:52:08,498 Some are radically different. 555 00:52:09,708 --> 00:52:10,658 It's very difficult to imagine. 556 00:52:10,659 --> 00:52:18,577 How all this beauty and complexity could emerge spontaneously from a few simple 557 00:52:18,727 --> 00:52:19,726 laws of nature. 558 00:52:25,226 --> 00:52:27,620 As snowflakes fall through the sky, they 559 00:52:27,621 --> 00:52:30,906 form and grow around a symmetrical framework. 560 00:52:33,324 --> 00:52:39,523 So if you start with an ice crystal and some part of it's got a flat bit, 561 00:52:40,413 --> 00:52:45,083 part of the hexagon if you like, and some bits a bit rough, then water 562 00:52:45,084 --> 00:52:49,122 molecules are more likely to bind to the rough bit than the flat bit. 563 00:52:49,402 --> 00:52:53,741 There are basically more ways for them, more sites for them to stick to. 564 00:52:54,341 --> 00:52:58,420 So that means that the rough bit will accumulate more molecules than the flat 565 00:52:58,620 --> 00:53:02,020 bit, and it'll build up faster until it gets flat. 566 00:53:02,530 --> 00:53:03,530 And then it'll slow down. 567 00:53:04,060 --> 00:53:09,499 So there's a tendency for the underlying structure of the ice crystals themselves 568 00:53:09,500 --> 00:53:12,558 to get echoed into bigger and bigger units. 569 00:53:14,618 --> 00:53:18,397 Then there's a second process called branching or the branch instability. 570 00:53:19,542 --> 00:53:24,476 That happens when the snowflake goes into a particularly humid region in a cloud. 571 00:53:24,696 --> 00:53:27,496 So that's a region where there are lots of water molecules available. 572 00:53:28,466 --> 00:53:31,075 So you get a little bump on the flat surface. 573 00:53:31,915 --> 00:53:37,155 That bump is more likely to have water molecules bind to it. 574 00:53:37,484 --> 00:53:39,434 It's got more binding sites, if you like. 575 00:53:39,494 --> 00:53:40,494 So it'll grow quickly. 576 00:53:40,495 --> 00:53:42,754 There are lots of water molecules available. 577 00:53:43,494 --> 00:53:45,527 So it'll grow into a spike and then other 578 00:53:45,528 --> 00:53:48,894 bumps can appear and they'll grow into spikes. 579 00:53:49,023 --> 00:53:53,892 So that's how you get that star-like, sharp structures on snowflakes. 580 00:53:55,282 --> 00:53:59,851 But then if the snowflake drifts back into a region that's less humid, so there are 581 00:53:59,852 --> 00:54:04,630 less water molecules available, then the faceting takes over again and 582 00:54:04,631 --> 00:54:08,130 smooth edges, hexagonal structures start to form. 583 00:54:08,805 --> 00:54:10,369 Then it goes into a humid region. 584 00:54:10,789 --> 00:54:12,909 And the branching takes over and you get the branches. 585 00:54:22,188 --> 00:54:24,697 It's a wonderfully complex and intricate process. 586 00:54:25,122 --> 00:54:29,356 And the thing I find most beautiful about it is that when you look at a snowflake, 587 00:54:29,806 --> 00:54:32,196 then you can read its entire history. 588 00:54:32,276 --> 00:54:35,036 You can see its history made solid. 589 00:54:38,515 --> 00:54:41,835 Every individual snowflake has a different history. 590 00:54:41,930 --> 00:54:45,135 Every snowflake followed a slightly different 591 00:54:45,136 --> 00:54:47,674 path through the clouds into the ground. 592 00:54:48,264 --> 00:54:53,293 And that means every snowflake grew in a subtly different way. 593 00:54:53,873 --> 00:54:57,152 And that's why no two snowflakes are ever alike. 594 00:54:57,472 --> 00:55:01,851 Because no two paths through time are ever alike. 595 00:55:09,170 --> 00:55:13,148 When you look at a snowflake, you see history 596 00:55:13,149 --> 00:55:17,030 and the deep structure of nature condensed. 597 00:55:17,389 --> 00:55:19,109 Into a frozen moment. 598 00:55:20,539 --> 00:55:24,398 How many stars it is together? 599 00:55:25,968 --> 00:55:27,517 You can see them so clearly. 600 00:55:30,617 --> 00:55:31,617 You look. 601 00:55:32,217 --> 00:55:35,436 It is wonderful, you know, that when you think about it, the whole universe, 602 00:55:35,556 --> 00:55:39,096 the whole of physics is contained in a snowflake. 603 00:55:39,706 --> 00:55:43,535 To describe them, you need all four forces of nature. 604 00:55:44,395 --> 00:55:47,321 You need gravity to allow the snowflake to fall 605 00:55:47,322 --> 00:55:49,454 down through the clouds and onto the ground. 606 00:55:49,455 --> 00:55:53,244 You need electromagnetism to stick all those water 607 00:55:53,245 --> 00:55:57,273 molecules together to form these beautiful crystals. 608 00:55:58,073 --> 00:56:03,012 You need the nuclear forces to stick the atomic nuclei of oxygen together. 609 00:56:03,772 --> 00:56:09,251 And then you need to understand about symmetry and symmetry breaking. 610 00:56:09,651 --> 00:56:13,256 All the fundamental ideas that underlie modern physics can 611 00:56:13,257 --> 00:56:16,810 be thought of in the journey of a snowflake to the ground. 612 00:56:28,118 --> 00:56:33,687 Every snowflake shares the same building blocks, the same basic, beautiful, 613 00:56:33,887 --> 00:56:37,467 symmetric forces of nature at their heart. 614 00:56:37,747 --> 00:56:40,746 But because of their histories, because of the way they formed, 615 00:56:40,986 --> 00:56:41,986 they're all different. 616 00:56:42,786 --> 00:56:44,366 And so it is with solar systems. 617 00:56:44,506 --> 00:56:45,865 So it is with planets. 618 00:56:46,185 --> 00:56:47,865 And so it is with people. 619 00:56:48,475 --> 00:56:52,684 We're all made out of the same building blocks, but we're all slightly and 620 00:56:52,685 --> 00:56:56,604 magnificently different because of the history of our formation. 621 00:57:04,847 --> 00:57:09,492 The structures we see in the universe, stars and planets and trees and 622 00:57:09,493 --> 00:57:12,711 snowflakes, are shadows of something deeper. 623 00:57:14,671 --> 00:57:19,070 They mask an underlying beauty and simplicity. 624 00:57:20,990 --> 00:57:28,529 But isn't it a beautiful thought that our origin and evolution, just like the 625 00:57:28,530 --> 00:57:32,165 structure of a snowflake in a snowstorm, can 626 00:57:32,265 --> 00:57:36,628 be explained by a few simple natural laws? 627 00:57:37,188 --> 00:57:40,479 And isn't it a wonderful idea that that thought came from 628 00:57:40,480 --> 00:57:45,266 just looking carefully at nature and trying to understand it? 54637

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