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Would you like to inspect the original subtitles? These are the user uploaded subtitles that are being translated: 1 00:00:09,240 --> 00:00:11,925 BRIAN COX: The natural world is beautiful 2 00:00:12,640 --> 00:00:14,483 but complex. 3 00:00:18,200 --> 00:00:20,487 The skies dance with color. 4 00:00:20,880 --> 00:00:22,803 CHILDREN: Yay! Yeah! 5 00:00:23,560 --> 00:00:25,403 COX: Shapes form 6 00:00:26,280 --> 00:00:27,691 and disappear. 7 00:00:28,200 --> 00:00:29,964 (CROWDS CHEERING) 8 00:00:32,800 --> 00:00:35,371 But this seemingly infinite complexity 9 00:00:35,440 --> 00:00:38,046 is just a shadow of something deeper, 10 00:00:38,320 --> 00:00:40,891 the underlying laws of nature. 11 00:00:47,240 --> 00:00:49,766 The world is beautiful to look at 12 00:00:50,160 --> 00:00:52,322 but it's even more beautiful to understand. 13 00:01:17,840 --> 00:01:19,126 Come on. 14 00:01:23,600 --> 00:01:25,250 COX: A regular day in the snow. 15 00:01:28,200 --> 00:01:29,725 CHILD: Bingo! Bingo! 16 00:01:30,560 --> 00:01:32,369 COX: But if you look carefully, 17 00:01:32,760 --> 00:01:34,364 there's something deeper. 18 00:01:38,680 --> 00:01:40,250 CHILD: This is fun. 19 00:01:43,320 --> 00:01:48,611 Everyone is perfect, pretty much. (CHUCKLING) 20 00:01:49,440 --> 00:01:52,569 Looks like they've been cut out of thin paper. 21 00:01:54,520 --> 00:01:56,090 I got one. 22 00:01:58,200 --> 00:02:02,922 Snowflakes are complex intricate things. They're all different, 23 00:02:03,000 --> 00:02:05,606 but there's something similar about them. 24 00:02:05,680 --> 00:02:07,444 They are beautiful. 25 00:02:07,640 --> 00:02:10,041 But there is also, I think, a deeper beauty, 26 00:02:10,120 --> 00:02:11,963 and that beauty is in an idea. 27 00:02:12,360 --> 00:02:15,921 The idea is that all the similarities and difference, 28 00:02:16,000 --> 00:02:19,447 the structure of snowflakes, can be explained 29 00:02:19,520 --> 00:02:22,490 using a few simple laws of nature. 30 00:02:22,560 --> 00:02:25,291 And that idea goes to the very heart of science, 31 00:02:25,360 --> 00:02:30,571 because those laws themselves are beautiful and they're universal. 32 00:02:30,640 --> 00:02:36,602 They can explain so many things from snowflakes to stars. 33 00:02:39,880 --> 00:02:41,928 How do snowflakes form? 34 00:02:43,440 --> 00:02:47,684 Why are they all different and yet tantalizingly similar? 35 00:02:51,680 --> 00:02:53,569 These are questions that can be asked about any 36 00:02:53,720 --> 00:02:55,961 naturally occurring structure. 37 00:02:59,480 --> 00:03:01,642 Why are beehives regular hexagons? 38 00:03:02,280 --> 00:03:04,408 Why do icebergs float? 39 00:03:05,200 --> 00:03:07,168 Why are planets spherical? 40 00:03:07,520 --> 00:03:10,000 And what's this got to do with free-diving grannies? 41 00:03:13,840 --> 00:03:16,207 The answers allow us to glimpse 42 00:03:16,360 --> 00:03:19,364 the underlying laws of nature that shaped them. 43 00:03:23,840 --> 00:03:26,491 This is why when you look at a snowflake, 44 00:03:28,920 --> 00:03:31,810 you're peering beyond the everyday world. 45 00:03:32,240 --> 00:03:35,483 At the deep structure of nature itself. 46 00:03:37,080 --> 00:03:39,287 The universe in a snowflake. 47 00:03:46,560 --> 00:03:48,801 GIRL: Wow, it's like a little star. 48 00:03:48,880 --> 00:03:52,282 It really looks like snow crystals stuck in a bubble. 49 00:03:52,360 --> 00:03:54,488 GIRL: (GASPS) Aww... 50 00:03:55,080 --> 00:03:56,081 (IN DISTINCT TALKING) 51 00:03:57,400 --> 00:03:58,401 Wow! 52 00:03:59,760 --> 00:04:03,526 COX: There '5 a shape that appears at all scales in the universe. 53 00:04:08,240 --> 00:04:09,685 Seen from space, 54 00:04:09,760 --> 00:04:12,525 the Earth is a near-perfect sphere, 55 00:04:15,720 --> 00:04:19,441 sculpted by one of the fundamental forces of nature. 56 00:04:26,360 --> 00:04:28,044 (SPEAKING OWN LANGUAGE) 57 00:04:34,200 --> 00:04:35,201 Ah! 58 00:04:45,720 --> 00:04:48,007 Carla and her friends are about to pit themselves 59 00:04:48,080 --> 00:04:50,890 against the force that shaped our planet. 60 00:04:52,840 --> 00:04:54,922 (SPEAKING OWN LANGUAGE) 61 00:04:55,760 --> 00:04:57,569 (CROWDS CHEERING) 62 00:05:04,000 --> 00:05:05,604 (CROWDS CHEERING) 63 00:05:19,440 --> 00:05:21,602 (CROWDS CHANTING) 64 00:05:23,000 --> 00:05:25,048 (SPEAKING OWN LANGUAGE) 65 00:05:43,160 --> 00:05:45,208 (SPEAKING OWN LANGUAGE) 66 00:05:52,760 --> 00:05:55,206 COX: These children are going into battle 67 00:05:56,440 --> 00:05:57,726 with gravity. 68 00:05:57,800 --> 00:06:00,201 (CROWDS CHEERING) 69 00:06:02,600 --> 00:06:04,409 (CROWDS CHANTING) 70 00:06:11,520 --> 00:06:13,329 COX: Towns from across Catalonia 71 00:06:15,920 --> 00:06:18,526 have gathered to enter into a fierce competition. 72 00:06:21,840 --> 00:06:23,888 To build a human tower 73 00:06:23,960 --> 00:06:25,564 as high as possible. 74 00:06:26,360 --> 00:06:28,249 (SPEAKING OWN LANGUAGE) 75 00:06:33,600 --> 00:06:35,568 COX: Mum and dad are here with their daughters 76 00:06:35,640 --> 00:06:37,290 Mariana and Carla 77 00:06:37,360 --> 00:06:39,761 to represent the town of Vilafranca. 78 00:06:43,680 --> 00:06:45,728 People of all ages take part, 79 00:06:45,800 --> 00:06:47,962 but it's the lightest members of the team, 80 00:06:48,040 --> 00:06:49,929 children as young as five, 81 00:06:50,000 --> 00:06:52,685 who ascend daringly to the summit. 82 00:06:56,320 --> 00:06:58,402 (SPEAKING OWN LANGUAGE) 83 00:07:02,000 --> 00:07:04,287 COX: The family put their trust in the most experienced 84 00:07:04,400 --> 00:07:06,084 members of the team, 85 00:07:06,160 --> 00:07:07,650 like David Miret. 86 00:07:08,520 --> 00:07:10,602 (DAVID SPEAKING OWN LANGUAGE) 87 00:07:40,680 --> 00:07:43,445 COX: David feels the weight of everyone above him 88 00:07:46,880 --> 00:07:50,009 as gravity pulls them down to the ground. 89 00:07:53,200 --> 00:07:56,647 And he knows the secret to defying gravity 90 00:07:56,800 --> 00:07:58,245 is geometry. 91 00:08:09,480 --> 00:08:12,290 COX: To support David and eventually the kids, 92 00:08:12,360 --> 00:08:14,840 the rest of the town all push inwards 93 00:08:15,000 --> 00:08:17,970 with equal force in all directions 94 00:08:18,240 --> 00:08:21,050 buttressing the tower from all sides. 95 00:08:25,040 --> 00:08:28,328 And this results in the emergence of a symmetrical shape 96 00:08:29,480 --> 00:08:30,811 a circle. 97 00:08:31,280 --> 00:08:33,931 No other shape gives the tower such strength. 98 00:08:46,080 --> 00:08:47,366 But gravity 99 00:08:47,440 --> 00:08:49,602 is unforgiving. 100 00:09:21,920 --> 00:09:26,050 Ana' that's a worry if your child is climbing to the top. 101 00:09:27,800 --> 00:09:29,882 (SPEAKING OWN LANGUAGE) 102 00:09:41,920 --> 00:09:44,002 (SPEAKING OWN LANGUAGE) 103 00:10:07,320 --> 00:10:09,926 (CROWDS APPLAUDING) 104 00:10:25,280 --> 00:10:27,487 (CROWD CHEERING) 105 00:11:00,120 --> 00:11:02,361 COX: It's clear that the force of gravity 106 00:11:02,440 --> 00:11:04,408 is unrelenting. 107 00:11:08,640 --> 00:11:10,210 The collapsing towers 108 00:11:10,280 --> 00:11:13,727 are shadows of the process that shaped our planet. 109 00:11:18,720 --> 00:11:21,849 These people aren't just falling towards the ground, 110 00:11:24,200 --> 00:11:27,044 they're falling towards the center of the Earth. 111 00:11:27,640 --> 00:11:30,211 And the Earth's gravity pulls everything down 112 00:11:32,880 --> 00:11:35,201 from people to snowflakes, 113 00:11:39,240 --> 00:11:42,005 to the very rock that the Earth is made of. 114 00:11:43,160 --> 00:11:46,881 And this is ultimately, why the Earth is spherical. 115 00:11:48,800 --> 00:11:52,043 So why does gravity sculpt things into spheres? 116 00:11:52,160 --> 00:11:56,006 Well, the first thing to say is that it doesn't, necessarily. 117 00:11:58,600 --> 00:12:00,329 If I pick up a snowball, 118 00:12:02,200 --> 00:12:05,647 it's not spherical, kind of an irregular shape. 119 00:12:07,000 --> 00:12:09,287 But if I apply pressure to it 120 00:12:09,360 --> 00:12:13,206 and squash it evenly in all directions, 121 00:12:14,400 --> 00:12:16,880 then I can turn that into a sphere. 122 00:12:17,440 --> 00:12:20,762 And that is what's happening with gravity. 123 00:12:21,040 --> 00:12:23,008 As I start adding mass to it, 124 00:12:23,080 --> 00:12:25,924 that gravitational pull becomes bigger. 125 00:12:26,160 --> 00:12:28,970 So, I'll get to a point where this snowball, 126 00:12:29,040 --> 00:12:30,769 if I kept adding mass to it, 127 00:12:30,840 --> 00:12:32,444 will be so massive 128 00:12:32,520 --> 00:12:35,729 that gravitational pull on its surface will be so strong 129 00:12:35,800 --> 00:12:40,806 that it would start to squash the material out of which it's made. 130 00:12:40,880 --> 00:12:42,245 In this case, snow, 131 00:12:42,320 --> 00:12:45,403 or in the case of a planet or moon, the rock. 132 00:12:45,480 --> 00:12:51,522 That pressure exerts on the surface equally in all directions, 133 00:12:51,600 --> 00:12:55,525 because gravity works equally in all directions. 134 00:12:56,640 --> 00:12:59,644 Well, you can ask the question, "How much matter do I need" 135 00:12:59,760 --> 00:13:01,330 "for gravity to get strong enough" 136 00:13:01,400 --> 00:13:04,210 "to start overcoming the strength of rock" 137 00:13:04,280 --> 00:13:06,248 "and sculpting things into spheres?" 138 00:13:06,760 --> 00:13:10,287 Well, that minimum size has got a name, 139 00:13:10,360 --> 00:13:12,886 it's a brilliant name, it's called the Potato Radius. 140 00:13:12,960 --> 00:13:17,170 You can see why, because things that are too small for gravity 141 00:13:17,240 --> 00:13:21,484 to be strong enough to sculpt them look like misshapen potatoes. 142 00:13:24,600 --> 00:13:28,366 The great thing is you don't even need to imagine it. 143 00:13:28,440 --> 00:13:30,090 You can calculate it. 144 00:13:30,160 --> 00:13:31,650 I did that this morning. 145 00:13:31,720 --> 00:13:35,406 And I got an answer, just roughly between 100 and 200 kilometers. 146 00:13:35,640 --> 00:13:38,883 The brilliant thing, the most beautiful thing 147 00:13:38,960 --> 00:13:40,530 is if you look up into space 148 00:13:40,600 --> 00:13:43,285 and look at the moons of Mars and Saturn and Jupiter 149 00:13:43,360 --> 00:13:45,647 and objects out there in the solar system, 150 00:13:45,720 --> 00:13:48,405 you'll find that, roughly speaking, 151 00:13:48,480 --> 00:13:51,484 if their radius is bigger than about 200 kilometers, 152 00:13:51,560 --> 00:13:53,050 they're beautiful spheres. 153 00:13:53,120 --> 00:13:56,329 And if the radius is less than about 200 kilometers 154 00:13:56,400 --> 00:13:59,483 they look more like misshapen potatoes. 155 00:13:59,560 --> 00:14:01,483 So, you can calculate it. 156 00:14:05,640 --> 00:14:07,244 COX: If you're small, 157 00:14:07,320 --> 00:14:09,846 spheres don't come easily. 158 00:14:12,560 --> 00:14:16,087 Even asteroids or moons don't quite manage it. 159 00:14:16,160 --> 00:14:19,448 The potato shape might be as close as you can get. 160 00:14:24,240 --> 00:14:26,686 But when you are the size of a planet, 161 00:14:26,760 --> 00:14:28,603 spheres come naturally. 162 00:14:36,240 --> 00:14:38,811 Four and a half billion years ago, 163 00:14:38,880 --> 00:14:42,646 rocks circling the sun began sticking together 164 00:14:42,720 --> 00:14:46,645 until they had sufficient mass for gravity to really get to work 165 00:14:47,400 --> 00:14:49,004 turning potato shapes 166 00:14:49,080 --> 00:14:51,845 into one very important sphere 167 00:14:51,920 --> 00:14:54,241 suspended in space. 168 00:15:00,000 --> 00:15:04,050 A universal law sculpted the familiar, elegant, 169 00:15:04,120 --> 00:15:05,963 symmetrical shape of our planet. 170 00:15:13,800 --> 00:15:19,091 But closer to the surface, it's littered with endless shapes and forms. 171 00:15:23,360 --> 00:15:26,603 And in every one of these naturally occurring structures, 172 00:15:27,160 --> 00:15:31,370 there are simple underlying laws waiting to be glimpsed. 173 00:15:37,360 --> 00:15:38,725 Here in the Himalayas 174 00:15:38,800 --> 00:15:43,010 there's a shape that's a shadow of a fundamental mathematical law. 175 00:15:46,720 --> 00:15:48,802 It's guarded by the Himalayan honey bee, 176 00:15:52,600 --> 00:15:55,410 the largest species of honey bee on the planet. 177 00:15:57,760 --> 00:16:01,560 And collecting honey from under their watchful compound eyes 178 00:16:02,120 --> 00:16:04,691 is one of the most dangerous jobs you could imagine. 179 00:16:12,880 --> 00:16:15,121 (SPEAKING OWN LANGUAGE) 180 00:16:25,560 --> 00:16:28,484 And today is the first time for one of the young villagers. 181 00:16:29,200 --> 00:16:31,043 Min and his nephew, Hiro, 182 00:16:31,120 --> 00:16:34,010 will be the ones leading the hunt for the precious honey. 183 00:16:34,760 --> 00:16:39,084 It's prized for its medicinal properties and sells for a high price. 184 00:16:53,600 --> 00:16:56,729 Hidden beneath the seething mass of bodies 185 00:16:56,800 --> 00:17:00,441 sits a network of exquisitely engineered hexagons. 186 00:17:05,040 --> 00:17:07,441 The bees appear to be master builders 187 00:17:07,520 --> 00:17:11,445 preforming structural calculations with architectural precision. 188 00:17:25,440 --> 00:17:28,762 The bees benefit from hidden mathematic law 189 00:17:28,840 --> 00:17:32,526 that explains why they build hexagons to store their honey. 190 00:17:33,120 --> 00:17:36,920 And twice a year, the Gurung people head into the mountains 191 00:17:37,000 --> 00:17:38,809 to exploit the bees' secret. 192 00:17:43,320 --> 00:17:45,243 Because it's Hiro's first time, 193 00:17:45,960 --> 00:17:48,566 this trip will be particularity challenging. 194 00:18:32,320 --> 00:18:35,449 The bees make their hives as inaccessible as possible 195 00:18:35,520 --> 00:18:37,284 to protect them from predators. 196 00:18:37,840 --> 00:18:39,080 (BELL CLANGING) 197 00:19:11,240 --> 00:19:16,201 The hives the bees are defending contain a vivid visible solution 198 00:19:16,400 --> 00:19:20,200 to a deep mathematic problem and a very practical one. 199 00:19:22,320 --> 00:19:25,051 They need to store honey to sustain their colony 200 00:19:25,120 --> 00:19:26,690 through the long winter months. 201 00:19:27,760 --> 00:19:29,683 They build their hives out of wax. 202 00:19:31,880 --> 00:19:34,929 But for every gram of wax a bee produces 203 00:19:35,000 --> 00:19:38,004 it will have to consume more than six grams of honey. 204 00:19:41,360 --> 00:19:43,681 So they benefit from building efficiently 205 00:19:44,160 --> 00:19:46,242 using as little wax as possible. 206 00:20:41,000 --> 00:20:44,049 Each sting is like a hypodermic needle. 207 00:20:45,440 --> 00:20:47,522 After the bees sting, they die, 208 00:20:50,920 --> 00:20:56,051 the ultimate sacrifice to guard the hexagons and the honey they hold. 209 00:22:16,400 --> 00:22:18,209 For Hiro, this is all about keeping 210 00:22:18,280 --> 00:22:21,204 the Gurung tradition of honey hunting alive. 211 00:22:24,520 --> 00:22:27,205 And the hexagon is at the heart of it all. 212 00:22:46,960 --> 00:22:50,043 So why do bees build hexagonal honeycombs? 213 00:22:52,480 --> 00:22:55,211 Well, that is in fact a very good question. 214 00:22:55,280 --> 00:22:57,009 It's actually a mathematical question. 215 00:22:59,800 --> 00:23:03,600 The problem is how do I divide up a volume 216 00:23:03,720 --> 00:23:08,089 into shapes of equal size using the minimum amount of stuff? 217 00:23:09,240 --> 00:23:11,641 Now, why does that matter to a bee? 218 00:23:11,720 --> 00:23:16,248 Because that stuff is wax and wax is extremely valuable to the bees. 219 00:23:16,840 --> 00:23:19,605 So what shape should it be? 220 00:23:20,040 --> 00:23:23,442 Should it be squares or should it be triangles? 221 00:23:23,560 --> 00:23:24,971 You can see it can't be circles, 222 00:23:25,080 --> 00:23:27,560 because circles, when you pack them together, leave gaps. 223 00:23:27,640 --> 00:23:29,369 So they're not very efficient. 224 00:23:29,440 --> 00:23:33,411 Or could it be that hexagons are the most efficient? 225 00:23:34,080 --> 00:23:39,325 Well, that is actually a simple sounding question with a very complicated answer. 226 00:23:39,400 --> 00:23:42,210 It's one of the oldest questions in mathematics. 227 00:23:42,280 --> 00:23:45,250 It's got a name actually, it's called the Honeycomb Conjecture. 228 00:23:45,320 --> 00:23:50,042 Mathematicians have worked on it for thousands and thousands of years, 229 00:23:50,480 --> 00:23:54,485 and it's only recently that the Honeycomb Conjecture was proved. 230 00:23:55,280 --> 00:23:56,361 Here's one of the proofs. 231 00:23:58,000 --> 00:23:59,445 A huge paper, 232 00:24:00,200 --> 00:24:03,363 pages and pages of complex mathematics, 233 00:24:04,160 --> 00:24:07,881 and it turns out that the hexagon is the most efficient shape. 234 00:24:08,400 --> 00:24:13,850 The bees knew what human mathematicians didn't know for thousands of years. 235 00:24:13,920 --> 00:24:17,208 Actually, I'm using "know" in quite a loose sense there. 236 00:24:17,280 --> 00:24:20,682 There's still a great deal of debate amongst biologists 237 00:24:20,760 --> 00:24:23,286 as to how the bees actually do it. 238 00:24:23,360 --> 00:24:27,081 Do they build hexagons from scratch 239 00:24:27,160 --> 00:24:30,482 using some kind of instinctive behavior? 240 00:24:30,560 --> 00:24:33,848 Or do they in fact build a simpler shape, perhaps circles, 241 00:24:33,920 --> 00:24:36,890 and then because the wax heats up, it can deform, 242 00:24:36,960 --> 00:24:41,363 and the laws of physics themselves change the circles into hexagons. 243 00:24:41,440 --> 00:24:42,965 That's still not agreed upon. 244 00:24:43,520 --> 00:24:47,684 But what is agreed upon by the mathematicians and the bees 245 00:24:47,760 --> 00:24:50,081 is the hexagon is the most efficient shape. 246 00:24:50,480 --> 00:24:52,369 That just shows you it's a beautiful thing. 247 00:24:52,440 --> 00:24:55,887 Mathematics is the universal language. 248 00:24:55,960 --> 00:24:58,088 I mean, when you look at a perfect honeycomb, 249 00:24:58,160 --> 00:25:02,563 you see a shadow of that language of mathematics 250 00:25:02,640 --> 00:25:05,450 made real by bees. 251 00:25:12,040 --> 00:25:14,805 Perfect shapes reveal simple laws. 252 00:25:20,320 --> 00:25:23,847 Whether it's spherical planets sculpted by gravity, 253 00:25:27,960 --> 00:25:30,088 pulling us to the center of the Earth, 254 00:25:34,800 --> 00:25:39,249 or the mathematically refined efficiency of hexagonal honeycombs, 255 00:25:42,920 --> 00:25:46,163 simple laws underpin the shapes we can see, 256 00:25:47,440 --> 00:25:48,851 and they're universal. 257 00:25:52,480 --> 00:25:54,448 But the action of these simple laws 258 00:25:54,560 --> 00:25:57,848 seems at odds with the complex shapes of life. 259 00:26:10,880 --> 00:26:12,769 These shallow springs are home 260 00:26:12,840 --> 00:26:15,969 to one of nature's seemingly less elegant shapes, 261 00:26:25,160 --> 00:26:26,207 the manatee. 262 00:26:27,640 --> 00:26:31,531 Like all marine animals, they're free from the effects of gravity. 263 00:26:32,000 --> 00:26:34,765 No need for strong bones to support their weight, 264 00:26:36,520 --> 00:26:39,808 but they don't have complete freedom from the laws of physics. 265 00:26:40,120 --> 00:26:42,691 MAN: (ON RADIO) Several manatees... 266 00:26:44,800 --> 00:26:46,086 COX: It's winter, 267 00:26:46,160 --> 00:26:49,369 and if the water temperature here drops below 20 degrees... 268 00:26:49,480 --> 00:26:51,761 WOMAN: (STATIC) Due to cold temperatures Friday morning... 269 00:26:52,360 --> 00:26:54,328 COX: For the manatee, it's deadly. 270 00:26:54,880 --> 00:26:56,520 WOMAN: (STATIC) Can be very dangerous... 271 00:26:56,560 --> 00:26:58,801 In search of warmer aquatic environments... 272 00:27:00,040 --> 00:27:03,931 COX: Manatees, like this female, are vegetarians. 273 00:27:05,640 --> 00:27:09,486 Basically, she's a 10-foot-long aquatic cow with no legs. 274 00:27:10,360 --> 00:27:13,569 To stay warm, she has to consume up to 50 kilograms 275 00:27:13,640 --> 00:27:15,802 of leaves and sea grass every day. 276 00:27:17,160 --> 00:27:19,845 And the females here are eating for others, too. 277 00:27:20,720 --> 00:27:23,291 This one is suckling two young calves. 278 00:27:23,920 --> 00:27:26,161 And the weather is only getting colder. 279 00:27:27,520 --> 00:27:30,285 WAYNE HARTLEY: Ooh, Lemon... 280 00:27:31,360 --> 00:27:32,441 Ruth. 281 00:27:36,600 --> 00:27:37,806 Looking good. 282 00:27:42,840 --> 00:27:45,241 Oh, there's Doug. Doug likes it up here now. 283 00:27:46,200 --> 00:27:49,409 COX: Researcher Wayne Hartley is doing this morning's head count, 284 00:27:49,760 --> 00:27:51,524 part of the manatee census. 285 00:27:56,320 --> 00:27:58,527 HARTLEY: It's a special thing to come to work, 286 00:28:00,400 --> 00:28:01,481 come down in the morning 287 00:28:02,480 --> 00:28:03,481 and it's quiet. 288 00:28:04,480 --> 00:28:06,130 The steam's coming off the water. 289 00:28:11,800 --> 00:28:15,805 You can hear the manatees out there breathing. It's just "whoosh." 290 00:28:17,720 --> 00:28:21,520 And they are so peaceful, they are so calm. 291 00:28:23,600 --> 00:28:27,730 Just watching manatees has gotta be good for your blood pressure 292 00:28:27,800 --> 00:28:29,643 or anything else that may ail you. 293 00:28:39,920 --> 00:28:42,605 COX: Biologist Amy Teague is working with Wayne 294 00:28:42,680 --> 00:28:44,444 to do a health check on the families. 295 00:28:46,480 --> 00:28:49,563 AMY: He '5 just sort of hanging around, checking things out. 296 00:28:49,640 --> 00:28:53,565 Er, manatees are very docile, uh, gentle creatures. 297 00:28:54,360 --> 00:28:57,967 Uh, but they are very curious, anything new in their environment 298 00:28:58,040 --> 00:28:59,804 they often like to come check out. 299 00:29:00,280 --> 00:29:03,250 Uh, so he's probably just checking me out. 300 00:29:04,400 --> 00:29:05,920 Yeah, he's just chewing on my flipper. 301 00:29:07,120 --> 00:29:09,088 Got 23.5 degrees Celsius. 302 00:29:10,280 --> 00:29:13,329 COX: Manatee families are drawn in from colder waters 303 00:29:13,400 --> 00:29:14,925 because this is a hot spring. 304 00:29:15,760 --> 00:29:17,888 And some make it just in time. 305 00:29:18,520 --> 00:29:20,761 He is severely cold stressed. 306 00:29:22,560 --> 00:29:24,483 HARTLEY: With the cold stress, they don't eat. 307 00:29:25,800 --> 00:29:27,768 Their immune system shuts down. 308 00:29:28,520 --> 00:29:31,808 AMY: They're here to keep themselves alive in the winter. 309 00:29:31,880 --> 00:29:35,043 They... They really require warm water. 310 00:29:39,680 --> 00:29:43,924 COX: It might look like these animals keep warm using blubber, like seals, 311 00:29:45,040 --> 00:29:48,010 but they're not fat, they're round. 312 00:29:49,240 --> 00:29:53,370 In terms of pure physics, the best way to stay warm is to be a sphere. 313 00:29:58,080 --> 00:30:02,130 It has the smallest surface area-to-volume ratio of any shape, 314 00:30:02,960 --> 00:30:05,281 less area for heat to escape from. 315 00:30:07,040 --> 00:30:10,442 A beautiful example with a naturally occurring shape 316 00:30:10,640 --> 00:30:13,246 reflecting a deeper mathematical law, 317 00:30:14,680 --> 00:30:17,684 the manatee could well be the most spherical mammal on Earth. 318 00:30:18,800 --> 00:30:20,290 What a wonderful thing to be. 319 00:30:26,400 --> 00:30:27,765 Sorry, their breath stinks. 320 00:30:27,920 --> 00:30:29,160 (LAUGHS) 321 00:30:29,240 --> 00:30:31,971 HARTLEY: To me, it smells like the inside of a hot truck tire. 322 00:30:37,080 --> 00:30:39,401 COX: But, of course, they're not perfect spheres. 323 00:30:41,520 --> 00:30:45,081 There are many other competing factors that determine their shape. 324 00:30:45,880 --> 00:30:49,851 Like all animals, they have to live, breathe, eat, 325 00:30:50,600 --> 00:30:52,204 and move. 326 00:30:55,200 --> 00:30:57,931 The manatee's natural habitat is shrinking, 327 00:30:58,600 --> 00:31:00,887 and they need to find warmth elsewhere. 328 00:31:04,720 --> 00:31:08,884 This power station helps provide energy for around nine million people. 329 00:31:09,800 --> 00:31:10,926 And, in the process, 330 00:31:11,040 --> 00:31:14,931 warms the water that keeps over half of Florida's manatees alive 331 00:31:15,120 --> 00:31:16,849 through the winter. 332 00:31:20,560 --> 00:31:23,006 The same families that Wayne and Amy study 333 00:31:23,440 --> 00:31:27,081 can end up here, over 300 kilometers away, 334 00:31:28,200 --> 00:31:31,647 where the mothers and calves can hold on to as much heat as possible 335 00:31:33,040 --> 00:31:34,644 because of their round bodies. 336 00:31:37,520 --> 00:31:38,601 To a physicist, 337 00:31:38,680 --> 00:31:42,605 the perfect shape for a manatee would be a symmetrical sphere, 338 00:31:43,400 --> 00:31:45,402 but biology complicates things. 339 00:31:47,280 --> 00:31:49,851 Manatees can't just bob around waiting for food 340 00:31:49,920 --> 00:31:51,763 or warmth to come to them. 341 00:31:52,960 --> 00:31:55,611 They need fins and a tail to move around 342 00:31:57,520 --> 00:32:00,888 whether that's to a hot spring or to a power station. 343 00:32:12,400 --> 00:32:17,327 The forces of nature sculpts and restricts the shapes of all things, 344 00:32:17,400 --> 00:32:21,962 the inanimate, like pebbles or rocks or cliffs, 345 00:32:22,120 --> 00:32:23,770 or living things. 346 00:32:26,520 --> 00:32:30,286 But, of course, basic physics is not the only force shaping life. 347 00:32:31,040 --> 00:32:32,371 (BEES BUZZING) 348 00:32:34,560 --> 00:32:38,929 Evolution by natural selection molds living things of a time 349 00:32:39,000 --> 00:32:41,082 in response to their environment 350 00:32:41,160 --> 00:32:43,322 and their interaction with other life forms, 351 00:32:48,200 --> 00:32:50,282 and it's had billions of years to do it. 352 00:32:53,000 --> 00:32:56,686 So, you can't understand the shape of living things 353 00:32:56,800 --> 00:32:59,201 without understanding their evolutionary history. 354 00:33:11,120 --> 00:33:13,521 (WOMAN SPEAKING KOREAN) 355 00:33:32,680 --> 00:33:35,251 COX: We're all the product of our experiences. 356 00:33:35,800 --> 00:33:41,045 Our history, our culture, our lives, make an indelible impression 357 00:33:42,120 --> 00:33:43,690 and make us all different. 358 00:33:48,840 --> 00:33:50,968 But we're also all similar, 359 00:33:51,920 --> 00:33:56,767 not just to each other as human beings but to countless other animals on Earth. 360 00:33:57,920 --> 00:34:00,207 We are obviously related. 361 00:34:04,360 --> 00:34:08,922 Most obviously, through the symmetry of our bodies. 362 00:34:16,600 --> 00:34:19,001 (WOMAN SPEAKING KOREAN) 363 00:34:22,760 --> 00:34:23,807 (WOMAN SPEAKING KOREAN) 364 00:34:30,000 --> 00:34:34,927 Mrs Chae and Miss Kim are Haenyo or Women of the Sea. 365 00:34:35,000 --> 00:34:37,844 They've grown up collecting seafood along these shores, 366 00:34:39,840 --> 00:34:40,966 and they still do. 367 00:34:41,360 --> 00:34:43,806 (WOMAN SPEAKING KOREAN) 368 00:34:47,960 --> 00:34:49,769 (LOCAL FOLK MUSIC PLAYING) 369 00:34:54,200 --> 00:34:56,521 The Haenyo are part of a dying tradition, 370 00:34:57,200 --> 00:34:59,202 not many youngsters are interested any more. 371 00:35:00,920 --> 00:35:04,367 It's hard work, especially if you're in your 70s. 372 00:35:05,240 --> 00:35:06,810 (MISS KIM SPEAKING KOREAN) 373 00:35:33,080 --> 00:35:36,368 COX: Right now, the women are catching conch or sea snails. 374 00:35:40,040 --> 00:35:44,011 It's a crucial time of year when they have a chance to make the most money. 375 00:35:56,880 --> 00:35:59,042 The tradition of free diving for food 376 00:35:59,120 --> 00:36:01,600 is part of these women's cultural history. 377 00:36:02,560 --> 00:36:05,086 But the details of the human form itself, 378 00:36:05,440 --> 00:36:09,764 in particular, its symmetry that allows them to dive, swim, and hunt 379 00:36:10,240 --> 00:36:12,561 is part of their evolutionary history. 380 00:36:17,440 --> 00:36:19,408 (SPEAKING KOREAN) 381 00:36:52,000 --> 00:36:56,562 COX: For Mrs Chae and Miss Kim, this is all about the search for food, 382 00:37:00,640 --> 00:37:04,122 and that's where the symmetrical structure of their bodies comes in, 383 00:37:04,720 --> 00:37:07,405 their blueprint that started out here in the oceans 384 00:37:07,760 --> 00:37:09,888 hundreds of millions of years ago. 385 00:37:13,600 --> 00:37:16,251 Very few animals have steered clear of it. 386 00:37:23,960 --> 00:37:25,086 (EXCLAIMS) 387 00:37:32,360 --> 00:37:34,249 (WOMAN SPEAKING KOREAN) 388 00:37:39,960 --> 00:37:43,760 COX: Life is, and always has been, a competition. 389 00:37:44,400 --> 00:37:46,448 In a free-floating world, 390 00:37:46,600 --> 00:37:48,967 life grew to adopt different types of symmetry 391 00:37:49,080 --> 00:37:50,320 to get what it needed. 392 00:37:53,400 --> 00:37:57,041 Some animals became round or radially symmetric 393 00:37:57,120 --> 00:38:00,806 organizing their sensory organs around a central axis. 394 00:38:01,840 --> 00:38:06,050 Rather than chasing down food, they waited for food to come to them. 395 00:38:08,160 --> 00:38:13,041 But in order to really go after prey, you need to leave that strategy behind. 396 00:38:16,600 --> 00:38:19,046 You need to be divided down the middle. 397 00:38:19,600 --> 00:38:22,922 That gives you two sides, bilateral symmetry. 398 00:38:23,160 --> 00:38:26,164 Basically, you have a left and a right. 399 00:38:29,920 --> 00:38:31,649 And you can build on this plan, 400 00:38:31,720 --> 00:38:37,045 with arms to grab and search and a head and a tail. 401 00:38:38,040 --> 00:38:40,520 All this means you can orientate yourself 402 00:38:41,280 --> 00:38:43,123 and really target your prey. 403 00:38:44,080 --> 00:38:45,286 (SPEAKING KOREAN) 404 00:38:51,720 --> 00:38:56,248 COX: This body plan has been selected for over hundreds of millions of years. 405 00:38:57,040 --> 00:38:59,327 It confers a survival advantage. 406 00:39:00,760 --> 00:39:05,607 And it turns out that all animals with brains are bilaterally symmetrical. 407 00:39:10,520 --> 00:39:15,128 Bilateral symmetry provided the agility that drove a spiral 408 00:39:15,240 --> 00:39:19,404 of cunning fast predators and skittish speedy prey. 409 00:39:20,760 --> 00:39:22,888 (SPEAKING KOREAN) 410 00:39:49,680 --> 00:39:54,402 COX: The beautiful symmetry of the human body, which we all take for granted, 411 00:39:55,080 --> 00:39:58,050 is the product of a sweeping majestic story 412 00:39:59,960 --> 00:40:03,009 stretching back to some of the earliest life on Earth. 413 00:40:12,840 --> 00:40:16,606 COX: So we can understand the symmetry of organisms 414 00:40:16,680 --> 00:40:19,445 by understanding their history. 415 00:40:21,600 --> 00:40:25,889 You're essentially seeing the results of evolution by natural selection 416 00:40:25,960 --> 00:40:30,807 over hundreds and millions, even billions of years. 417 00:40:34,040 --> 00:40:39,251 But how do you understand the structure and symmetry of a snowflake? 418 00:40:39,720 --> 00:40:42,246 There's no natural selection here. 419 00:40:42,320 --> 00:40:46,882 There's no DNA to record and reproduce information. 420 00:40:47,120 --> 00:40:52,365 These things arise spontaneously from basic laws of physics. 421 00:40:54,440 --> 00:40:56,408 GIRL: Bingo! Bingo! 422 00:40:57,240 --> 00:40:58,241 Oh, bingo! 423 00:40:59,040 --> 00:41:03,204 COX: The intricate beauty of a snowflake is at first sight baffling, 424 00:41:03,480 --> 00:41:05,642 given the simplicity of their story. 425 00:41:06,800 --> 00:41:09,167 But in fact, it's a gift. 426 00:41:10,000 --> 00:41:12,287 A gift of almost nothing. 427 00:41:12,520 --> 00:41:14,204 One frozen moment 428 00:41:14,520 --> 00:41:17,444 that can reveal how the underlying laws of nature 429 00:41:17,920 --> 00:41:20,844 can lead to seemingly infinite complexity. 430 00:41:26,120 --> 00:41:30,887 Because snowflakes form in minutes and they're made out of a single ingredient 431 00:41:31,440 --> 00:41:35,126 with strange properties that give rise to a vast array 432 00:41:35,200 --> 00:41:40,240 of naturally occurring forms of all shapes, sizes, and behaviors. 433 00:41:44,520 --> 00:41:45,646 Ice. 434 00:41:46,400 --> 00:41:48,084 (FOG HORN) 435 00:41:53,800 --> 00:41:57,282 NEIL RIGGS: It's so mystical when you leave in the morning in the fog. 436 00:41:58,440 --> 00:42:00,488 You're just looking around 437 00:42:02,240 --> 00:42:04,925 and then you see these shapes that come out of the fog. 438 00:42:05,320 --> 00:42:06,845 (FOG HORN) 439 00:42:14,840 --> 00:42:17,081 DOUG ALLAN: They are big, big heavy objects, 440 00:42:17,160 --> 00:42:21,529 far bigger than anything that we've created, floating on the sea. 441 00:42:26,880 --> 00:42:28,689 (FOG HORN) 442 00:42:41,840 --> 00:42:45,322 We've got to remember, it was an iceberg that sailed passed Newfoundland 443 00:42:45,400 --> 00:42:47,562 which ended up sinking the Titanic. 444 00:42:50,840 --> 00:42:53,684 COX: Doug Allan is here because it's iceberg season. 445 00:42:56,200 --> 00:42:58,168 He's part of a scientific expedition. 446 00:42:58,760 --> 00:43:02,606 Every summer, thousands of icebergs float south from the Arctic 447 00:43:02,680 --> 00:43:06,571 into the shipping lanes and oil fields off the coast of Newfoundland. 448 00:43:09,000 --> 00:43:13,722 This team are here to help protect those multi-billion-dollar industries 449 00:43:13,800 --> 00:43:17,930 by trying to understand more about where the icebergs are heading. 450 00:43:18,960 --> 00:43:22,009 The man leading the expedition is Neil Riggs. 451 00:43:22,240 --> 00:43:24,129 So, we put it back in the water again, OK, 452 00:43:24,200 --> 00:43:27,522 and if we lose control, then we take it in, we secure it. 453 00:43:27,640 --> 00:43:29,688 And if that goes nowhere, we go home. 454 00:43:32,880 --> 00:43:35,486 COX: The big problem with icebergs is simple. 455 00:43:35,840 --> 00:43:37,171 They float. 456 00:43:44,600 --> 00:43:49,003 RIGGS: Iceberg ice reflects radar 69 times less effectively 457 00:43:49,080 --> 00:43:51,287 than a ship with the same cross-sectional area. 458 00:43:53,760 --> 00:43:55,922 (INDISTINCT) 459 00:43:57,680 --> 00:44:00,570 So, you could be sailing along and doing very good seamanship, 460 00:44:00,680 --> 00:44:02,696 looking at your radar, and there's the thing, all of a sudden, 461 00:44:02,720 --> 00:44:03,926 and you're upon it. 462 00:44:04,080 --> 00:44:07,482 And it's still a massive piece of ice relative to your ship. 463 00:44:07,720 --> 00:44:10,326 So, it could make a nice little hole. 464 00:44:11,920 --> 00:44:14,491 COX: The team will have to understand the influence 465 00:44:14,600 --> 00:44:17,570 of a large number of variables if they are to distinguish 466 00:44:17,640 --> 00:44:20,723 between harmless icebergs and dangerous ones. 467 00:44:21,760 --> 00:44:23,056 ALLAN: It's a complicated jigsaw. 468 00:44:23,080 --> 00:44:25,447 It's a little bit... You could think of it as a crime scene 469 00:44:25,520 --> 00:44:28,967 where you have the forensic people go in and they pick up little bits of clues, 470 00:44:29,040 --> 00:44:31,122 and together, you make a bigger picture. 471 00:44:32,560 --> 00:44:36,121 What I'm doing is just adding my little piece to the overall picture 472 00:44:36,200 --> 00:44:40,489 and hopefully helping their mathematical models to be more real. 473 00:44:42,840 --> 00:44:45,161 COX: Doug is a specialist cold-water diver. 474 00:44:46,240 --> 00:44:49,722 It's his job to photograph the underside of the icebergs. 475 00:44:50,440 --> 00:44:51,771 We'll go over to some of those 476 00:44:51,840 --> 00:44:53,330 - smaller pieces. - OK. 477 00:44:53,400 --> 00:44:54,401 OK. 478 00:44:54,960 --> 00:44:57,456 Yes, Captain Manning, we are OK to put the divers in the water now... 479 00:44:57,480 --> 00:44:59,721 COX: Rick Stanley is looking after safety. 480 00:45:05,520 --> 00:45:06,776 RICK STANLEY: Who knows what's gonna happen. 481 00:45:06,800 --> 00:45:12,807 There's so much pressure in this ice that it blows, it explodes. 482 00:45:13,040 --> 00:45:17,568 But there's pressure in there that can blow a piece of iceberg off the ice 483 00:45:17,640 --> 00:45:19,404 probably 15 or 20 feet. 484 00:45:19,640 --> 00:45:22,041 (RUMBLING) 485 00:45:26,560 --> 00:45:29,086 ALLAN: And we were just puttering around and suddenly, 486 00:45:29,160 --> 00:45:32,084 with no warning at all, the whole thing split in half, 487 00:45:32,160 --> 00:45:35,369 and it was almost like it was all falling into each other. 488 00:45:43,440 --> 00:45:45,488 This might be a bit unstable. 489 00:45:45,560 --> 00:45:47,050 - I'm not... - This is a huge berg. 490 00:45:47,920 --> 00:45:51,083 I'd rather dive round one that wasn't falling apart. 491 00:45:51,200 --> 00:45:52,201 Yeah. 492 00:45:55,920 --> 00:45:58,287 COX: These giant frozen mountains 493 00:45:58,360 --> 00:46:00,931 are born from the most innocent beginnings. 494 00:46:06,400 --> 00:46:07,731 Snowflakes. 495 00:46:10,240 --> 00:46:14,404 Over thousands of years, they're compressed to form glaciers 496 00:46:14,760 --> 00:46:17,411 that then break off to form icebergs. 497 00:46:18,040 --> 00:46:21,931 An average one weighs 200,000 tonnes. 498 00:46:23,800 --> 00:46:28,249 And that, give or take, is around 100 trillion snowflakes 499 00:46:28,320 --> 00:46:32,006 that form the structures that the expedition is trying to model, 500 00:46:32,080 --> 00:46:37,086 using a combination of sonar robots and Doug's first-hand observations. 501 00:46:39,200 --> 00:46:41,885 ALLAN: I basically have a good look at one side of the berg 502 00:46:41,960 --> 00:46:44,566 between the surface and 30 meters. 503 00:46:44,760 --> 00:46:48,082 Tell them what I saw and it will mean that they can interpret 504 00:46:48,200 --> 00:46:49,440 the sonar data that comes back. 505 00:46:49,520 --> 00:46:52,330 They'll get a better idea of it if I've seen it for myself. 506 00:47:21,800 --> 00:47:25,282 It's quite eerie going down the side of the iceberg. 507 00:47:26,840 --> 00:47:31,880 You're going down into the darkness, into the blue, into the green, 508 00:47:37,640 --> 00:47:41,008 and very occasionally there'll be this really loud thump, 509 00:47:41,080 --> 00:47:44,289 just like someone had hit you with the flat of their hand 510 00:47:44,360 --> 00:47:45,725 in the center of your chest, 511 00:47:47,440 --> 00:47:50,091 where the iceberg is banging on the bottom. 512 00:47:58,680 --> 00:48:00,603 You really don't want to go too far down 513 00:48:00,680 --> 00:48:04,730 because there is a real danger of being squished by the iceberg underneath. 514 00:48:09,960 --> 00:48:13,931 Well, you always worry when divers are in the water. But iceberg diving 515 00:48:14,000 --> 00:48:18,642 there's even more of that anticipation and excitement that goes on 516 00:48:18,720 --> 00:48:20,722 in the lower part of your belly. 517 00:48:29,840 --> 00:48:32,684 ALLAN: So you're swimming and you begin to see the details. 518 00:48:32,760 --> 00:48:35,730 You begin to realize that this is not 519 00:48:35,800 --> 00:48:38,929 a flat wall of ice going into the depths. 520 00:48:39,000 --> 00:48:41,731 This has tiny little dimples on it. Which... 521 00:48:41,800 --> 00:48:44,531 It almost looks like a giant golf ball. 522 00:48:50,840 --> 00:48:53,411 COX: These features are added to the models 523 00:48:53,480 --> 00:48:56,529 to understand how they affect the way the icebergs float 524 00:48:56,600 --> 00:49:00,525 and travel over long distances and into the shipping lanes. 525 00:49:02,480 --> 00:49:05,643 It's good to contribute to science at a basic level like this 526 00:49:05,720 --> 00:49:07,802 when the science is still developing, 527 00:49:07,880 --> 00:49:10,406 to come in, take some shots which help the scientists. 528 00:49:10,480 --> 00:49:11,527 That's really useful. 529 00:49:17,240 --> 00:49:19,163 COX: For all their unpredictability, 530 00:49:19,520 --> 00:49:22,888 there is regularity in the behavior of icebergs 531 00:49:25,760 --> 00:49:30,084 if you look carefully and ask the right questions, 532 00:49:30,520 --> 00:49:33,091 which is what science is all about. 533 00:49:39,120 --> 00:49:41,282 And the simplest question of all 534 00:49:41,360 --> 00:49:44,330 is about the most obvious part of their behavior. 535 00:49:47,360 --> 00:49:48,850 Why does ice float? 536 00:49:51,080 --> 00:49:52,650 That's not a naive question 537 00:49:52,720 --> 00:49:57,044 because no other commonly occurring solid floats on its own liquid. 538 00:49:59,160 --> 00:50:03,210 The answer lies in the structure of the water molecule itself. 539 00:50:04,800 --> 00:50:08,282 Think of what a molecule is. Take a water molecule, for example. 540 00:50:08,880 --> 00:50:12,521 It's two hydrogen atoms stuck to an oxygen atom. 541 00:50:12,880 --> 00:50:15,247 That's two hydrogen nuclei, 542 00:50:15,560 --> 00:50:17,642 which have positive electric charge 543 00:50:18,040 --> 00:50:20,611 sticking to an oxygen nucleus, 544 00:50:20,680 --> 00:50:22,728 which has a positive electric charge. 545 00:50:22,800 --> 00:50:26,282 And they are surrounded by negatively charged electrons. 546 00:50:26,360 --> 00:50:28,681 That's what sticks the atoms together. 547 00:50:28,960 --> 00:50:31,008 See, the negatively charged electrons 548 00:50:31,080 --> 00:50:34,801 tend to cluster around the oxygen nucleus 549 00:50:34,880 --> 00:50:41,490 leaving those two legs of hydrogen slightly positively charged. 550 00:50:41,680 --> 00:50:43,967 That means those positive charges 551 00:50:44,040 --> 00:50:47,931 can attract other negatively charged ends 552 00:50:48,000 --> 00:50:49,843 of other water molecules. 553 00:50:49,920 --> 00:50:54,847 So, an oxygen can come and orientate itself and bond to that leg. 554 00:50:55,240 --> 00:50:58,323 The other side, another oxygen from another water molecule 555 00:50:58,400 --> 00:51:02,405 will be attracted to the positive charge and bond to that leg. 556 00:51:02,480 --> 00:51:05,529 On the top, you get a hydrogen in and bond into that leg. 557 00:51:05,600 --> 00:51:07,921 So, you can see, you build up a structure. 558 00:51:08,000 --> 00:51:09,843 An open crystal structure. 559 00:51:10,200 --> 00:51:13,329 A shape which is actually hexagonal. 560 00:51:13,600 --> 00:51:17,082 And it's that property, that open structure, 561 00:51:17,160 --> 00:51:20,004 which is a reflection of the underlying structure 562 00:51:20,080 --> 00:51:22,082 of the water molecule itself, 563 00:51:22,160 --> 00:51:27,883 that leads to the solid ice being less dense than the liquid. 564 00:51:28,160 --> 00:51:34,964 And that is why ice cubes and icebergs float on liquid water. 565 00:51:39,040 --> 00:51:41,407 The hexagonal structure of ice 566 00:51:41,520 --> 00:51:46,003 is a shadow of the forces of nature that hold molecules together. 567 00:51:50,040 --> 00:51:53,681 Forces that shape every molecule of water 568 00:51:54,920 --> 00:51:59,084 and that create the six-fold symmetry of snowflakes. 569 00:52:03,640 --> 00:52:07,770 You can tell they're all the same thing. They're all six-sided. 570 00:52:09,120 --> 00:52:12,203 And yet, you can also see, just by eye, 571 00:52:12,280 --> 00:52:15,648 that every one is different, some are radically different. 572 00:52:16,240 --> 00:52:21,246 It's very difficult to imagine how all this beauty and complexity 573 00:52:21,320 --> 00:52:26,884 could emerge spontaneously from a few simple laws of nature. 574 00:52:31,720 --> 00:52:34,007 As snowflakes fall through the sky, 575 00:52:34,080 --> 00:52:37,562 they form and grow around a symmetrical framework. 576 00:52:39,880 --> 00:52:46,490 So if you start with an ice crystal and some part of it has got a flat bit, 577 00:52:47,000 --> 00:52:50,322 part of the hexagon, if you like, and some bits a bit rough, 578 00:52:50,720 --> 00:52:54,008 then water molecules are more likely to bind 579 00:52:54,080 --> 00:52:55,923 to the rough bit than the flat bit. 580 00:52:56,240 --> 00:53:00,768 There are basically more ways for them, more sites for them to stick to. 581 00:53:00,880 --> 00:53:02,325 So, that means that the rough bits 582 00:53:02,400 --> 00:53:05,609 will accumulate more molecules than the flat bits, 583 00:53:05,680 --> 00:53:09,048 and it will build up faster until it gets flat. 584 00:53:09,120 --> 00:53:10,360 And then, it will slow down. 585 00:53:10,440 --> 00:53:15,002 So, there's a tendency for the underlying structure 586 00:53:15,080 --> 00:53:19,802 of the ice crystals themselves to get echoed into bigger and bigger units. 587 00:53:21,200 --> 00:53:25,728 Then, there's a second process called branching or the branch instability. 588 00:53:26,000 --> 00:53:27,809 That happens when the snowflake 589 00:53:28,000 --> 00:53:31,288 goes into a particularly humid region in a cloud. 590 00:53:31,440 --> 00:53:34,603 So, that's a region where there are lots of water molecules available. 591 00:53:34,960 --> 00:53:38,043 So, you get a little bump on the flat surface. 592 00:53:38,480 --> 00:53:44,010 That bump is more likely to have water molecules bind to it. 593 00:53:44,080 --> 00:53:46,128 It's got more binding sites, if you like, 594 00:53:46,200 --> 00:53:47,406 so it will grow quickly 595 00:53:47,480 --> 00:53:50,006 if there are lots of water molecules available. 596 00:53:50,080 --> 00:53:52,003 So, it will grow into a spike, 597 00:53:52,080 --> 00:53:55,482 and then other bumps can appear, and they'll grow into spikes. 598 00:53:55,560 --> 00:54:00,726 So that's how you get that star-like sharp structures on snowflakes. 599 00:54:01,840 --> 00:54:06,209 But, then, if the snowflake drifts back into a region that's less humid, 600 00:54:06,280 --> 00:54:08,567 so there are less water molecules available, 601 00:54:08,640 --> 00:54:10,847 then the faceting takes over again. 602 00:54:11,080 --> 00:54:15,051 And smooth edges, hexagonal structures start to form. 603 00:54:15,400 --> 00:54:17,323 Then, it goes into a humid region, 604 00:54:17,400 --> 00:54:20,882 and the branching takes over and you get the branches. 605 00:54:28,760 --> 00:54:31,730 It's a wonderfully complex and intricate process. 606 00:54:31,920 --> 00:54:34,161 And the thing I find most beautiful about it 607 00:54:34,240 --> 00:54:39,041 is that when you look at a snowflake, then you can read its entire history. 608 00:54:39,120 --> 00:54:42,363 You can see its history made solid. 609 00:54:45,040 --> 00:54:48,965 Every individual snowflake has a different history. 610 00:54:49,240 --> 00:54:50,651 Every snowflake 611 00:54:50,720 --> 00:54:54,725 followed a slightly different path through the clouds onto the ground. 612 00:54:54,840 --> 00:55:00,404 And that means every snowflake grew in a subtly different way. 613 00:55:00,480 --> 00:55:04,246 And that's why no two snowflakes are ever alike, 614 00:55:04,320 --> 00:55:08,848 because no two paths through time are ever alike. 615 00:55:16,480 --> 00:55:20,041 COX: When you look at a snowflake, you see history 616 00:55:20,120 --> 00:55:26,207 and the deep structure of nature condensed into a frozen moment. 617 00:55:29,000 --> 00:55:31,446 CHILD: Look how many stars it is together. 618 00:55:32,480 --> 00:55:34,926 WOMAN: You can see them so clearly. 619 00:55:36,720 --> 00:55:38,290 You look. 620 00:55:38,760 --> 00:55:41,286 COX: It is wonderful, you know, that when you think about it, 621 00:55:41,360 --> 00:55:45,843 the whole universe, the whole of physics is contained in a snowflake. 622 00:55:46,880 --> 00:55:50,930 To describe them, you need all four forces of nature. 623 00:55:51,000 --> 00:55:54,766 You need gravity to allow the snowflake to fall down 624 00:55:54,840 --> 00:55:56,729 through the clouds and onto the ground. 625 00:55:56,800 --> 00:55:58,643 You need electro magnetism 626 00:55:58,720 --> 00:56:01,610 to stick all those water molecules together 627 00:56:01,680 --> 00:56:04,604 to form these beautiful crystals. 628 00:56:04,680 --> 00:56:08,446 You need the nuclear forces to stick the atomic nuclei 629 00:56:08,520 --> 00:56:10,363 of oxygen together. 630 00:56:10,440 --> 00:56:14,411 And then you need to understand about symmetry 631 00:56:14,480 --> 00:56:16,403 and symmetry breaking. 632 00:56:16,480 --> 00:56:19,927 All the fundamental ideas that underline modern physics 633 00:56:20,000 --> 00:56:23,891 can be thought of in the journey of a snowflake to the ground. 634 00:56:27,120 --> 00:56:30,329 Oh, look, how many stars do you think there are? 635 00:56:30,400 --> 00:56:32,129 Oh, wow! 636 00:56:34,520 --> 00:56:38,320 COX: Every snowflake shares the same building blocks, 637 00:56:38,400 --> 00:56:43,042 the same basic beautiful symmetric forces of nature 638 00:56:43,120 --> 00:56:44,724 at their heart. 639 00:56:44,800 --> 00:56:47,724 But because of their histories, because of the way they formed, 640 00:56:47,800 --> 00:56:49,245 they're all different. 641 00:56:49,320 --> 00:56:53,166 And so it is with solar systems, so it is with planets, 642 00:56:53,240 --> 00:56:55,049 and so it is with people. 643 00:56:55,120 --> 00:56:57,327 We're all made out of the same building blocks, 644 00:56:57,400 --> 00:57:01,246 but we're all slightly and magnificently different 645 00:57:01,320 --> 00:57:03,766 because of the history of our formation. 646 00:57:11,480 --> 00:57:15,201 The structures we see in the universe, stars and planets 647 00:57:15,320 --> 00:57:17,607 and trees and snowflakes 648 00:57:17,680 --> 00:57:19,921 are shadows of something deeper. 649 00:57:22,040 --> 00:57:26,762 They mask an underlying beauty and simplicity. 650 00:57:28,360 --> 00:57:33,764 But isn't it a beautiful thought that our origin and evolution, 651 00:57:34,200 --> 00:57:37,249 just like the structure of a snowflake 652 00:57:37,320 --> 00:57:39,926 in a snow storm, can be explained 653 00:57:40,000 --> 00:57:43,402 by a few simple natural laws. 654 00:57:43,800 --> 00:57:46,007 And isn't it a wonderful idea 655 00:57:46,080 --> 00:57:50,529 that that thought came from just looking carefully at nature 656 00:57:50,600 --> 00:57:52,329 and trying to understand it. 657 00:57:57,000 --> 00:57:59,002 (MUSIC PLAYING) 54296

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