1 00:00:02,000 --> 00:00:03,040 Take one. 2 00:00:04,560 --> 00:00:05,680 Shall we? 3 00:00:05,680 --> 00:00:06,720 Take a minute. 4 00:00:08,440 --> 00:00:09,600 Look around you. 5 00:00:11,240 --> 00:00:14,240 You probably never think about it, but we are living in a time 6 00:00:14,240 --> 00:00:16,520 of incredible ingenuity. 7 00:00:16,520 --> 00:00:21,080 Our lives are filled with fiendishly clever bits of tech that basically 8 00:00:21,080 --> 00:00:23,280 make the modern world tick. 9 00:00:24,360 --> 00:00:28,160 The problem is we're now so used to these devices... 10 00:00:29,320 --> 00:00:32,800 ..that we have forgotten to remember how clever they are. 11 00:00:32,800 --> 00:00:34,440 SPEAKER: I don't have an answer for that. 12 00:00:35,640 --> 00:00:38,040 I'm Professor Hannah Fry, 13 00:00:38,040 --> 00:00:40,440 your hammer-wielding, 14 00:00:40,440 --> 00:00:43,320 tech-curious tour guide... 15 00:00:43,320 --> 00:00:44,920 Whoo! 16 00:00:44,920 --> 00:00:47,800 ..to the secret genius of everyday objects. 17 00:00:47,800 --> 00:00:50,400 There is one law of physics that you need to know. 18 00:00:50,400 --> 00:00:52,680 In each episode... 19 00:00:52,680 --> 00:00:54,000 Whoa! 20 00:00:54,000 --> 00:00:57,320 ..I will take one seemingly ordinary item... 21 00:00:59,080 --> 00:01:00,120 Immediately smoking. 22 00:01:01,800 --> 00:01:04,080 ..and I'll look at it in frankly... 23 00:01:04,080 --> 00:01:05,480 Yeah! 24 00:01:05,480 --> 00:01:07,320 ..obscene detail... 25 00:01:07,320 --> 00:01:09,120 Two googly eyes. 26 00:01:09,120 --> 00:01:12,080 It has 180-degree view. 27 00:01:12,080 --> 00:01:14,960 ..meet the people who helped make it... 28 00:01:15,920 --> 00:01:17,960 This is the very first air fryer. 29 00:01:17,960 --> 00:01:21,880 ..and follow the twisty turny journey through the history 30 00:01:21,880 --> 00:01:23,080 of its invention. 31 00:01:23,080 --> 00:01:27,080 If you overshoot the turning point, don't try to do this. 32 00:01:27,080 --> 00:01:28,640 It's wobbly, Johnny. 33 00:01:28,640 --> 00:01:30,160 Yeah, it's just the wind. 34 00:01:32,840 --> 00:01:36,080 This time, it's the fridge. 35 00:01:38,000 --> 00:01:40,680 Pretty much every other appliance that you get in your kitchen 36 00:01:40,680 --> 00:01:43,200 is all about creating heat, 37 00:01:43,200 --> 00:01:45,680 but we've had the whole cooking with fire thing down 38 00:01:45,680 --> 00:01:47,480 for a very long time. 39 00:01:47,480 --> 00:01:49,440 Sucking heat out of your food, 40 00:01:49,440 --> 00:01:53,320 however - that is a lot trickier. 41 00:01:53,320 --> 00:01:57,640 So how did this quietly cool customer come to be? 42 00:01:57,640 --> 00:01:59,280 Whoa. Whoa. 43 00:02:00,600 --> 00:02:05,080 It is the story of one man's explosive invention in the 1800s... 44 00:02:05,080 --> 00:02:08,720 He almost blows himself up a couple of times, but it was worth it. 45 00:02:08,720 --> 00:02:10,640 I feel like we're sort of matching. 46 00:02:10,640 --> 00:02:13,160 ..a 17th-century chicken incubator... 47 00:02:13,160 --> 00:02:14,480 Look at that. 48 00:02:14,480 --> 00:02:16,280 ..and a revelation... 49 00:02:16,280 --> 00:02:19,800 There's no doubt that CFCs are endangering the planet. 50 00:02:19,800 --> 00:02:22,360 ..that set fridges against the world. 51 00:02:23,400 --> 00:02:24,800 It's always the quiet ones, isn't it? 52 00:02:33,120 --> 00:02:35,800 The fridge has been keeping it cool in the kitchen 53 00:02:35,800 --> 00:02:37,920 for just over 100 years. 54 00:02:39,080 --> 00:02:42,400 From Hotpoints to Bekos, Samsungs to Smegs, 55 00:02:42,400 --> 00:02:46,280 fridges are found in over a billion homes worldwide. 56 00:02:48,840 --> 00:02:53,000 I'm in Germany to go behind the scenes at appliance giant BSH, 57 00:02:53,000 --> 00:02:55,480 maker of all things Bosch. 58 00:02:58,600 --> 00:03:02,440 They're the biggest fridge manufacturer in Europe. 59 00:03:02,440 --> 00:03:06,080 They have their own railway line to get fridges to market. 60 00:03:07,600 --> 00:03:11,600 And I'm going to check out the first one they ever made. 61 00:03:11,600 --> 00:03:12,720 This is very cute. 62 00:03:12,720 --> 00:03:14,120 I would have this in my home. 63 00:03:14,120 --> 00:03:15,880 Oh, really? Yeah. It's from the '30s. 64 00:03:15,880 --> 00:03:19,320 And so it was one of our first electric fridges we produced. 65 00:03:20,440 --> 00:03:22,880 Meet Daniel Schweigert. 66 00:03:22,880 --> 00:03:27,240 He's in charge of the production line here and is also 67 00:03:27,240 --> 00:03:29,080 a rather charming host. 68 00:03:30,080 --> 00:03:31,520 Do you want to have something to drink? 69 00:03:31,520 --> 00:03:33,560 Obviously. Yeah. Come on. 70 00:03:33,560 --> 00:03:35,160 Water? Yeah. 71 00:03:35,160 --> 00:03:36,760 Great. Here you go. It's cold. 72 00:03:36,760 --> 00:03:38,400 Yeah, of course it is. 73 00:03:38,400 --> 00:03:39,600 Keep it chill. 74 00:03:39,600 --> 00:03:43,520 This is just a 100-year-old fridge that still works. 75 00:03:43,520 --> 00:03:46,720 I imagine in the 1930s, this was like a genuine revelation. 76 00:03:46,720 --> 00:03:48,440 Yes. Was it expensive? 77 00:03:48,440 --> 00:03:51,200 I think it was three months of salary back then. 78 00:03:51,200 --> 00:03:53,720 Three months' wages. Yeah. So a lot of money for them. 79 00:03:53,720 --> 00:03:56,040 Also very aesthetically pleasing. 80 00:03:56,040 --> 00:03:57,920 Maybe not that practical as a design. 81 00:03:57,920 --> 00:04:00,560 Yeah, but it still looks cool. 82 00:04:00,560 --> 00:04:02,040 It looks really cool. 83 00:04:03,280 --> 00:04:05,880 So how does this old fridge... 84 00:04:07,480 --> 00:04:09,280 ..and all the others that have followed... 85 00:04:10,320 --> 00:04:11,920 ..keep its cool? 86 00:04:17,320 --> 00:04:21,560 Well, stick on those mitts and hold on to your hats, folks. 87 00:04:23,600 --> 00:04:27,840 We're going to take apart the fridge and look at everything 88 00:04:27,840 --> 00:04:29,560 from its smart thermostat... 89 00:04:31,520 --> 00:04:33,760 ..to its snuggly insulation. 90 00:04:35,400 --> 00:04:38,840 But we're starting with all of these twisty, turny, tubey bits 91 00:04:38,840 --> 00:04:40,400 that create the cold. 92 00:04:41,640 --> 00:04:43,560 It's the cooling system. 93 00:04:46,400 --> 00:04:49,640 On Bosch's production line, around 5,000 fridges 94 00:04:49,640 --> 00:04:51,080 are produced every day. 95 00:04:53,040 --> 00:04:57,880 So that is 1.5 million cooling systems assembled each year. 96 00:04:59,400 --> 00:05:02,120 And it starts...with this bit. 97 00:05:03,440 --> 00:05:07,040 This goes inside the cooling appliances and extracts the heat. 98 00:05:07,040 --> 00:05:08,320 Sitting at the back of the fridge? 99 00:05:08,320 --> 00:05:09,680 No, it's inside the fridge. 100 00:05:09,680 --> 00:05:12,440 Inside? Yes, inside. OK. 101 00:05:12,440 --> 00:05:15,680 The cooling system is essentially a component of two halves. 102 00:05:15,680 --> 00:05:18,840 There's this cold bit hidden inside your fridge... 103 00:05:18,840 --> 00:05:20,200 And then what else do you need? 104 00:05:20,200 --> 00:05:21,680 We need this part. 105 00:05:21,680 --> 00:05:23,480 It's a condenser. 106 00:05:23,480 --> 00:05:26,960 You might be more familiar with it as the weirdly warm grill 107 00:05:26,960 --> 00:05:28,360 that gets all dusty. 108 00:05:29,360 --> 00:05:30,920 So this bit is the hot bit at the back? 109 00:05:30,920 --> 00:05:32,080 Yeah, it's the hot bit. 110 00:05:33,200 --> 00:05:38,480 The two parts are connected by a pump that drives the whole thing. 111 00:05:39,440 --> 00:05:41,040 It's heavy. Try it. 112 00:05:41,040 --> 00:05:42,800 Yeah. 113 00:05:42,800 --> 00:05:46,640 The finished cooling system is what makes your fridge cold, 114 00:05:46,640 --> 00:05:49,760 but not how you might think. 115 00:05:49,760 --> 00:05:52,040 I think people imagine that when it comes to fridges, you're, like, 116 00:05:52,040 --> 00:05:55,320 blasting cold air in, but you're not, right? 117 00:05:55,320 --> 00:05:57,440 You're taking heat out. 118 00:05:57,440 --> 00:05:58,640 Yeah. That's correct. 119 00:05:58,640 --> 00:06:02,600 Extract the heat from the inside and gives it to the environment. 120 00:06:02,600 --> 00:06:08,720 It is a nifty trick, all thanks to a hot bit, a cold bit, and a pump. 121 00:06:08,720 --> 00:06:09,920 So, all right, then. 122 00:06:09,920 --> 00:06:11,560 That's it really, isn't it? Bish, bash, Bosch! 123 00:06:11,560 --> 00:06:13,720 More or less, yes. Bish, bash, Bosch. 124 00:06:15,320 --> 00:06:18,440 They can thank me for that bit of marketing genius later. 125 00:06:19,800 --> 00:06:23,520 As for exactly how the cooling system works, 126 00:06:23,520 --> 00:06:25,560 let's get back to basics... 127 00:06:28,400 --> 00:06:30,880 ..at Fry's Fridge School. 128 00:06:30,880 --> 00:06:34,560 We are in a place where people normally learn how to fix 129 00:06:34,560 --> 00:06:38,720 the fridges, but I plan to do the exact opposite. 130 00:06:41,760 --> 00:06:43,400 Thank you for your service, fridge. 131 00:06:43,400 --> 00:06:46,360 I'm going to take you apart, but I'm not going to take you apart in a way 132 00:06:46,360 --> 00:06:49,200 which means you're going to be able to be put back together, so... 133 00:06:50,520 --> 00:06:52,920 This old thing was headed for recycling, 134 00:06:52,920 --> 00:06:56,480 which should be the endgame for any unfixable fridge. 135 00:06:56,480 --> 00:07:00,120 Faulty fridges aren't common, but their flammable innards 136 00:07:00,120 --> 00:07:01,760 do pose a fire risk. 137 00:07:03,080 --> 00:07:07,160 So it goes without saying, dear viewer, you must absolutely not 138 00:07:07,160 --> 00:07:08,680 do this at home. 139 00:07:11,240 --> 00:07:14,760 I'm extracting the cooling system, starting with the hot bit, 140 00:07:14,760 --> 00:07:19,080 where heat from inside the fridge radiates away into the room... 141 00:07:20,200 --> 00:07:23,360 This is the bit that gets warm, and then the compressor underneath. 142 00:07:25,080 --> 00:07:30,320 ..and the cold bit helpfully buried inside layers of insulation. 143 00:07:30,320 --> 00:07:32,680 Oh, this is going to be fun. 144 00:07:34,000 --> 00:07:36,160 I feel like an ancient Greek sculptor. 145 00:07:39,480 --> 00:07:40,760 CRASHING 146 00:07:42,000 --> 00:07:43,280 Think that was the shelves. 147 00:07:45,880 --> 00:07:47,680 Yeah! 148 00:07:47,680 --> 00:07:51,160 This is much more fun than playing with tiny screws, isn't it? 149 00:07:51,160 --> 00:07:53,880 Oh, yes, there it is. 150 00:07:55,040 --> 00:07:56,680 Whew! Cold bit. 151 00:07:57,880 --> 00:08:00,880 Looks a bit different to Bosch's fancy pants cold bit, 152 00:08:00,880 --> 00:08:02,960 but it does the same thing. 153 00:08:02,960 --> 00:08:06,320 And now easy access to your eggs and milk. 154 00:08:06,320 --> 00:08:11,560 These rather indecorously presented innards are where the magic happens. 155 00:08:11,560 --> 00:08:13,920 Or what happened before I tore it apart. 156 00:08:13,920 --> 00:08:16,840 So here we have the slightly mangled cooling system. 157 00:08:16,840 --> 00:08:18,440 That's actually a really terrible name. 158 00:08:18,440 --> 00:08:21,680 It should be called the heat-moving system because, 159 00:08:21,680 --> 00:08:26,080 according to the laws of physics, cold isn't a thing. 160 00:08:26,080 --> 00:08:29,160 Cold is just the absence of heat. 161 00:08:29,160 --> 00:08:31,040 You can't cool something down. 162 00:08:31,040 --> 00:08:33,520 You can only take heat away. 163 00:08:33,520 --> 00:08:38,680 And that is what this one system is designed to do. 164 00:08:38,680 --> 00:08:42,800 At its heart, the cooling system is just a giant snaking tube. 165 00:08:42,800 --> 00:08:47,480 It is filled with a substance that is liquid in some parts 166 00:08:47,480 --> 00:08:50,320 and a gas in others. 167 00:08:50,320 --> 00:08:53,160 The substance is unsurprisingly called refrigerant. 168 00:08:53,160 --> 00:08:55,240 More on that later. 169 00:08:55,240 --> 00:08:58,880 But it's the switch between liquid and gas that's crucial. 170 00:08:58,880 --> 00:09:02,080 One switch happens here in the evaporator. 171 00:09:02,080 --> 00:09:03,920 You pop something in the fridge, 172 00:09:03,920 --> 00:09:08,600 the heat of that thing gets absorbed by this part. 173 00:09:08,600 --> 00:09:11,640 The refrigerant comes into the evaporator as liquid 174 00:09:11,640 --> 00:09:13,120 and sprays out as gas. 175 00:09:13,120 --> 00:09:15,800 And that process needs energy. 176 00:09:15,800 --> 00:09:20,160 The gas absorbs all of the heat from anything 177 00:09:20,160 --> 00:09:22,600 that you have inside the fridge cabinet. 178 00:09:22,600 --> 00:09:26,280 All that heat energy then comes back round here, all the way up here, 179 00:09:26,280 --> 00:09:28,720 and then into this part... 180 00:09:29,760 --> 00:09:31,520 ..a pump called the compressor. 181 00:09:32,640 --> 00:09:37,440 This, as the name might suggest, is compressing that gas, 182 00:09:37,440 --> 00:09:41,680 pumping, and pumping, and pumping to increase the pressure. 183 00:09:41,680 --> 00:09:45,080 The compressor drives the refrigerant through the cooling system, 184 00:09:45,080 --> 00:09:48,480 taking all that absorbed heat energy with it. 185 00:09:48,480 --> 00:09:49,600 As it comes out here, then, 186 00:09:49,600 --> 00:09:53,000 you've got this hot high-pressure gas that comes along 187 00:09:53,000 --> 00:09:58,400 this tube, snakes its way all the way around, up and down, and up and down, 188 00:09:58,400 --> 00:10:02,560 radiating heat out into the room as it goes. 189 00:10:02,560 --> 00:10:06,760 And all the while it's condensing back into a liquid... 190 00:10:07,800 --> 00:10:11,920 ..ready to start another loop back in the same system again. 191 00:10:13,200 --> 00:10:17,480 It's called the vapour compression cooling cycle, and it moves heat 192 00:10:17,480 --> 00:10:21,000 energy in the opposite direction to the way it wants to go, 193 00:10:21,000 --> 00:10:24,920 creating a cold space here and pushing heat energy out into 194 00:10:24,920 --> 00:10:26,680 an already warm room here. 195 00:10:26,680 --> 00:10:29,360 It's basically designed to cheat physics. 196 00:10:30,520 --> 00:10:33,280 This is a one-way street for heat. 197 00:10:33,280 --> 00:10:37,560 It's being absorbed from anything that you put inside your fridge 198 00:10:37,560 --> 00:10:40,640 and then radiated out into the room 199 00:10:40,640 --> 00:10:42,440 via this whole contraption. 200 00:10:44,000 --> 00:10:48,840 So how did we figure out such a trick to shift heat to keep cool 201 00:10:48,840 --> 00:10:49,880 in the kitchen? 202 00:10:51,480 --> 00:10:54,680 Well, it all started with our enduring obsession 203 00:10:54,680 --> 00:10:57,400 with cold, hard cash. 204 00:11:00,120 --> 00:11:01,520 Just imagine - 205 00:11:01,520 --> 00:11:04,520 the Industrial Revolution is in full swing, 206 00:11:04,520 --> 00:11:08,520 but when it comes to keeping cool, things are still very much stuck 207 00:11:08,520 --> 00:11:09,720 in the ice age. 208 00:11:09,720 --> 00:11:12,920 I mean, they quite literally used ice. 209 00:11:15,000 --> 00:11:16,720 The rivers yield a frozen harvest - 210 00:11:16,720 --> 00:11:18,240 natural ice. 211 00:11:18,240 --> 00:11:22,520 The ice kings of New England harvested ice from frozen lakes 212 00:11:22,520 --> 00:11:26,720 and shipped it around the world, making them stupendously rich. 213 00:11:28,160 --> 00:11:31,320 The demand was so great that a race began to invent a machine 214 00:11:31,320 --> 00:11:34,520 that could make ice, powered by steam. 215 00:11:35,920 --> 00:11:40,240 But the first attempt, built in 1834, didn't deliver anything 216 00:11:40,240 --> 00:11:43,240 like enough ice to crack the US market. 217 00:11:46,840 --> 00:11:51,040 Instead, the breakthrough came, perhaps unsurprisingly, somewhere 218 00:11:51,040 --> 00:11:54,720 with almost no natural ice to harvest at all. 219 00:11:54,720 --> 00:11:55,840 Australia. 220 00:11:57,280 --> 00:12:01,720 In Geelong in southern Australia in the 1840s, there was a Scot called 221 00:12:01,720 --> 00:12:05,200 James Harrison who was running the local newspaper, and that meant 222 00:12:05,200 --> 00:12:09,640 he was very well aware of the issues that were facing the new colonies, 223 00:12:09,640 --> 00:12:14,120 including the fact that they really struggled to keep anything cold. 224 00:12:14,120 --> 00:12:17,000 Now, every now and then, there would be a shipment of ice, 225 00:12:17,000 --> 00:12:20,400 but it was rare and extremely expensive. 226 00:12:20,400 --> 00:12:23,080 In fact, the story goes that when the gold rush happened, 227 00:12:23,080 --> 00:12:26,160 the prospectors who had a good day would go to the local hotel 228 00:12:26,160 --> 00:12:27,560 and buy everyone whisky... 229 00:12:27,560 --> 00:12:29,240 Give me a shot of a nugget nectar. 230 00:12:29,240 --> 00:12:33,120 ..but the prospectors who'd had a really, really good day 231 00:12:33,120 --> 00:12:35,800 would buy whisky with ice. 232 00:12:35,800 --> 00:12:40,360 Harrison had studied chemistry and mechanics and so spotted 233 00:12:40,360 --> 00:12:42,320 that this was an opportunity. 234 00:12:43,440 --> 00:12:47,320 Sheepskins were the country's main export, but the mutton mountain 235 00:12:47,320 --> 00:12:50,000 left behind just went to waste. 236 00:12:50,000 --> 00:12:53,080 Keeping food fresh was all but impossible. 237 00:12:53,080 --> 00:12:57,360 And so, probably aware of earlier failed attempts, he decided 238 00:12:57,360 --> 00:13:00,960 to have a go at creating cold himself. 239 00:13:04,080 --> 00:13:07,720 So Harrison goes off to a cave in a nearby riverbank, 240 00:13:07,720 --> 00:13:09,400 and he starts experimenting. 241 00:13:09,400 --> 00:13:11,680 I mean, he almost blows himself up a couple of times, 242 00:13:11,680 --> 00:13:12,960 but it was worth it... 243 00:13:14,160 --> 00:13:18,760 ..because, by 1855, he has built and patented 244 00:13:18,760 --> 00:13:24,560 a prototype of an ice-making machine that actually works. 245 00:13:24,560 --> 00:13:29,400 Harrison's invention was massive, with a steam-powered piston 246 00:13:29,400 --> 00:13:31,160 driving the cooling system. 247 00:13:31,160 --> 00:13:36,160 It was snapped up by businesses to chill that Aussie beer, of course, 248 00:13:36,160 --> 00:13:39,560 and deep-freeze food for transport and storage. 249 00:13:41,000 --> 00:13:44,240 And thanks to Harrison, we're doing the same today, 250 00:13:44,240 --> 00:13:48,480 just in giant cold store facilities like this one in North London. 251 00:13:48,480 --> 00:13:50,680 I mean, this is like, what, 1800s, right? 252 00:13:50,680 --> 00:13:54,040 How much does this have to do with the kind of big fridges 253 00:13:54,040 --> 00:13:56,160 that you get here? Quite a lot. 254 00:13:56,160 --> 00:13:58,720 There are a lot of the components are essentially the same. 255 00:13:58,720 --> 00:14:02,080 We're still using that vapour compression cycle today. 256 00:14:02,080 --> 00:14:04,280 That is Lisa-Jayne Cook... 257 00:14:05,480 --> 00:14:08,560 ..president of the UK's Institute of Refrigeration 258 00:14:08,560 --> 00:14:11,960 and the woman to call if you want to talk industrial-scale cooling. 259 00:14:13,360 --> 00:14:16,480 I mean, this feels like a giant leap forwards. 260 00:14:16,480 --> 00:14:17,520 Yeah, it was. 261 00:14:17,520 --> 00:14:19,440 What is actually going on in all of this bit? 262 00:14:19,440 --> 00:14:21,800 So, in the middle is the compressor elements. 263 00:14:21,800 --> 00:14:25,440 The gas gets condensed over here, and then it goes 264 00:14:25,440 --> 00:14:29,640 through into the evaporator, which then produces the cold side. 265 00:14:29,640 --> 00:14:32,440 What's interesting about Harrison's invention - cos there were a lot 266 00:14:32,440 --> 00:14:35,520 of other people already understanding the principles of it, 267 00:14:35,520 --> 00:14:37,360 but they hadn't got that loop quite yet. 268 00:14:37,360 --> 00:14:39,480 And that's the bit that makes this really genius. 269 00:14:39,480 --> 00:14:40,600 Yes. 270 00:14:40,600 --> 00:14:44,920 The telltale signs of Harrison's cooling cycle are everywhere here... 271 00:14:46,320 --> 00:14:49,280 ..like this hot bit on the outside. 272 00:14:51,000 --> 00:14:53,200 Guess by the sound that these are the compressors. 273 00:14:53,200 --> 00:14:54,760 They are the compressors. They're loud. 274 00:14:54,760 --> 00:14:56,640 They are very loud. 275 00:14:56,640 --> 00:14:58,160 While inside... 276 00:14:58,160 --> 00:15:00,880 Because I am a newbie, I'm bringing a hat. 277 00:15:00,880 --> 00:15:03,840 ..it is absolutely Baltic. 278 00:15:03,840 --> 00:15:05,680 Oh, my gosh, that is cold. 279 00:15:05,680 --> 00:15:07,000 It is really cold. 280 00:15:07,000 --> 00:15:09,760 But it like hits you as you come in. 281 00:15:09,760 --> 00:15:14,800 This giant cold store can freeze up to 2,500 pallets of food. 282 00:15:14,800 --> 00:15:16,680 It's crazy. 283 00:15:16,680 --> 00:15:20,480 You can suck out that much energy out of a space that's this big? 284 00:15:20,480 --> 00:15:22,320 It is incredible. 285 00:15:22,320 --> 00:15:23,720 Thanks to Harrison, 286 00:15:23,720 --> 00:15:27,360 the vapour compression cooling system had arrived. 287 00:15:27,360 --> 00:15:29,360 I mean, you wouldn't last long in here, would you? 288 00:15:30,760 --> 00:15:35,720 Like this place, it provided cooling for commercial customers. 289 00:15:35,720 --> 00:15:38,520 But its steam-powered compressor was never going to fit 290 00:15:38,520 --> 00:15:39,720 in your kitchen. 291 00:15:43,720 --> 00:15:47,960 For domestic cooling, we must thank another unlikely hero - 292 00:15:47,960 --> 00:15:51,000 French priest Marcel Audiffren. 293 00:15:51,000 --> 00:15:55,800 It's 1894, and at his Cistercian monastery, he has a big problem - 294 00:15:55,800 --> 00:15:58,400 keeping the wine cold for the monks. 295 00:16:01,240 --> 00:16:04,680 Luckily, Marcel also teaches physics, and so is pretty 296 00:16:04,680 --> 00:16:07,200 well-qualified to find a solution. 297 00:16:07,200 --> 00:16:11,920 And so he constructs an ingenious hand-cranked compressor that sends 298 00:16:11,920 --> 00:16:15,880 coolant through pipes in an insulated cabinet 299 00:16:15,880 --> 00:16:19,360 and which, crucially, fits in the wine cellar. 300 00:16:19,360 --> 00:16:23,560 He calls his device the dumbbell and patents it in France. 301 00:16:26,160 --> 00:16:29,400 But it catches the attention of bigwigs at American 302 00:16:29,400 --> 00:16:31,200 company General Electric. 303 00:16:32,520 --> 00:16:37,360 In 1911, they release the electric Audiffren refrigerating machine. 304 00:16:38,920 --> 00:16:40,200 At $1,000, 305 00:16:40,200 --> 00:16:44,640 it costs more than the average American makes in a year. 306 00:16:44,640 --> 00:16:48,240 But the fridge as we know it had arrived. 307 00:16:48,240 --> 00:16:51,000 And with it came societal change that went 308 00:16:51,000 --> 00:16:53,320 far beyond an ice-cold drink. 309 00:16:55,200 --> 00:16:58,520 That cooling system that was built for these giant ice machines 310 00:16:58,520 --> 00:17:01,840 was then shrunk down and put into domestic appliances, 311 00:17:01,840 --> 00:17:06,040 and that meant that this wasn't just a technological triumph 312 00:17:06,040 --> 00:17:08,760 because, OK, it might have been the ideas of a long line 313 00:17:08,760 --> 00:17:14,280 of men, but it was women for whom this had a profound effect. 314 00:17:14,280 --> 00:17:18,160 Because now that they had fridges, all of a sudden that daily grind 315 00:17:18,160 --> 00:17:21,720 of shopping and cooking fresh had a release. 316 00:17:21,720 --> 00:17:24,800 Leftovers, all of a sudden, were a thing, 317 00:17:24,800 --> 00:17:27,480 and you could even go wild - 318 00:17:27,480 --> 00:17:30,880 reheat food that had been cooked by somebody else. 319 00:17:32,400 --> 00:17:35,120 Science presents the modern housewife with the refrigerator. 320 00:17:35,120 --> 00:17:39,080 The arrival of appliances like the fridge in the early-20th century 321 00:17:39,080 --> 00:17:42,480 were a game-changer for the lives of women at a time 322 00:17:42,480 --> 00:17:45,240 of transformational change. 323 00:17:45,240 --> 00:17:48,200 Women have joined the men in the production line, 324 00:17:48,200 --> 00:17:51,600 and the percentage of women in industry is expected to be much 325 00:17:51,600 --> 00:17:52,880 higher very soon. 326 00:17:54,000 --> 00:17:57,920 Through the 1940s and '50s, women were joining the workforce 327 00:17:57,920 --> 00:17:59,640 in significant numbers. 328 00:17:59,640 --> 00:18:03,880 Finally, we were living the dream, working and still 329 00:18:03,880 --> 00:18:05,240 doing the housework. 330 00:18:05,240 --> 00:18:08,800 Of course, I don't let George know how easy homemaking has become 331 00:18:08,800 --> 00:18:10,560 with modern equipment. 332 00:18:10,560 --> 00:18:14,920 And by the 1980s, the fridge had become the kitchen staple 333 00:18:14,920 --> 00:18:16,120 we know today. 334 00:18:20,320 --> 00:18:23,760 The cooling system might be the heart of your fridge, 335 00:18:23,760 --> 00:18:27,160 but it wouldn't work at all without our next component. 336 00:18:28,680 --> 00:18:32,520 Time to find out what's in those twisty, turny tubes. 337 00:18:33,800 --> 00:18:35,960 It's the refrigerant. 338 00:18:39,880 --> 00:18:43,960 And back at Bosch, we are at the next step of the production line. 339 00:18:46,080 --> 00:18:49,440 Here, in this area, we have the cooling system complete, 340 00:18:49,440 --> 00:18:52,920 and now we need to breathe life into the refrigerator. 341 00:18:52,920 --> 00:18:54,240 Breathe life. Yeah. 342 00:18:54,240 --> 00:18:55,360 I like it. 343 00:18:55,360 --> 00:18:57,280 That is Zoi Zachari... 344 00:18:58,360 --> 00:19:01,640 ..the woman who puts the actual lifeblood into your fridge. 345 00:19:03,520 --> 00:19:04,960 What does the refrigerant do? 346 00:19:04,960 --> 00:19:09,240 A refrigerant absorbs the heat from the food you have inside 347 00:19:09,240 --> 00:19:13,000 and bring it outside through the condenser. 348 00:19:13,000 --> 00:19:14,160 How much do you put in? 349 00:19:14,160 --> 00:19:17,040 Between 35-55g. 350 00:19:17,040 --> 00:19:18,280 Sorry, grams? 351 00:19:18,280 --> 00:19:20,720 Grams, yes. 35 grams? You see it here. 352 00:19:20,720 --> 00:19:22,440 You see it here. 353 00:19:22,440 --> 00:19:25,320 That's like what? Ten teaspoons? Yeah. 354 00:19:25,320 --> 00:19:28,920 And this is circulating the whole time you have your fridge. 355 00:19:28,920 --> 00:19:31,320 Just ten teaspoons going round and round and round and round 356 00:19:31,320 --> 00:19:33,280 and round forever. Yeah. Exactly. 357 00:19:33,280 --> 00:19:34,440 Wow. 358 00:19:34,440 --> 00:19:36,960 If you put more, I think it can blow up. 359 00:19:38,080 --> 00:19:40,080 Which no-one wants. 360 00:19:40,080 --> 00:19:44,840 Obviously, Zoi is joking, but this stuff is flammable. 361 00:19:44,840 --> 00:19:47,520 The tiny amount of refrigerant gets injected 362 00:19:47,520 --> 00:19:49,480 into the fridge's cooling system. 363 00:19:49,480 --> 00:19:51,000 And so, naturally... 364 00:19:51,000 --> 00:19:52,400 Can I do one? 365 00:19:52,400 --> 00:19:53,440 Ah! 366 00:19:53,440 --> 00:19:55,160 Um, I don't know. 367 00:19:55,160 --> 00:19:57,240 Do you want to try it? Yes, I do. 368 00:19:57,240 --> 00:19:58,520 OK. 369 00:19:58,520 --> 00:20:00,000 Let me ask. 370 00:20:00,000 --> 00:20:01,040 OK. 371 00:20:01,040 --> 00:20:03,200 Long story short - I can. 372 00:20:04,240 --> 00:20:06,240 If I get it wrong, what happens? 373 00:20:06,240 --> 00:20:07,400 There will be a voice. 374 00:20:07,400 --> 00:20:09,680 An alarm? An alarm, yeah. 375 00:20:09,680 --> 00:20:12,320 You will hear it if you make a mistake. If I mess up. 376 00:20:12,320 --> 00:20:14,040 No pressure. 377 00:20:14,040 --> 00:20:15,200 Yeah. 378 00:20:15,200 --> 00:20:16,400 OK. 379 00:20:16,400 --> 00:20:18,040 Slightly regretting it now. 380 00:20:18,040 --> 00:20:20,120 OK, so like this? Yes. 381 00:20:22,440 --> 00:20:23,640 There we go. 382 00:20:23,640 --> 00:20:25,360 The pipes are connected, 383 00:20:25,360 --> 00:20:27,440 the system is ready, 384 00:20:27,440 --> 00:20:30,480 and the refrigerant can, theoretically, flow. 385 00:20:30,480 --> 00:20:32,880 So that's it, then? It's like the liquid is in there. 386 00:20:32,880 --> 00:20:34,560 It's staying in there. Yeah. 387 00:20:34,560 --> 00:20:36,840 So I've got a few minutes to wait until I know 388 00:20:36,840 --> 00:20:38,560 whether I've mucked it up. 389 00:20:38,560 --> 00:20:40,880 Number five. That's it. 390 00:20:40,880 --> 00:20:44,880 At the end of the production line, the cooling system is sealed shut, 391 00:20:44,880 --> 00:20:49,000 with its shot of refrigerant locked in there for the fridge's lifetime. 392 00:20:49,000 --> 00:20:50,920 Oh, this is my one. 393 00:20:50,920 --> 00:20:53,160 This is number five. Yes. 394 00:20:53,160 --> 00:20:54,440 Ah. 395 00:20:54,440 --> 00:20:55,480 It's fine. Great. 396 00:20:55,480 --> 00:20:56,680 Was that an alarm? No. 397 00:20:56,680 --> 00:20:58,000 Oh. It wasn't. 398 00:20:58,000 --> 00:21:00,000 Everything OK. 399 00:21:00,000 --> 00:21:01,120 You guys! 400 00:21:02,720 --> 00:21:05,880 So, how does that tiny amount of refrigerant give 401 00:21:05,880 --> 00:21:08,080 the fridge its cooling powers? 402 00:21:09,320 --> 00:21:11,680 Let's discuss it over a drink. 403 00:21:11,680 --> 00:21:13,600 It's got to be cold, doesn't it? 404 00:21:15,600 --> 00:21:19,360 And with a few bits and bobs from behind the bar, 405 00:21:19,360 --> 00:21:20,720 I'm going to show you. 406 00:21:22,880 --> 00:21:25,800 OK, I have here some isobutane. 407 00:21:25,800 --> 00:21:30,240 Now, this is the refrigerant that you get in most modern fridges. 408 00:21:30,240 --> 00:21:33,320 Now, this stuff is flammable and dangerous to inhale 409 00:21:33,320 --> 00:21:36,760 in large amounts, so don't go decanting this at home. 410 00:21:36,760 --> 00:21:39,080 I'll just pour... Oh, you know what? 411 00:21:39,080 --> 00:21:40,120 Safety first. 412 00:21:42,600 --> 00:21:44,080 OK, right. 413 00:21:44,080 --> 00:21:49,200 Thing about isobutane is that it can exist as a gas at room temperature, 414 00:21:49,200 --> 00:21:52,520 but if I just pour some of this in here, 415 00:21:52,520 --> 00:21:54,600 you can get it as liquid. 416 00:21:56,080 --> 00:21:57,360 Now, already... 417 00:21:58,920 --> 00:21:59,960 ..this stuff... 418 00:22:01,080 --> 00:22:02,920 ..oh, it feels really cold. 419 00:22:05,920 --> 00:22:09,800 And the reason is that the surface of the isobutane is evaporating. 420 00:22:09,800 --> 00:22:12,280 It's kind of turning into gas. 421 00:22:12,280 --> 00:22:14,640 But to do that, it needs energy. 422 00:22:14,640 --> 00:22:18,400 And so it is taking in heat energy from the dish that it's in, 423 00:22:18,400 --> 00:22:20,760 but also my fingers. 424 00:22:20,760 --> 00:22:26,000 This is exactly how your fridge takes heat energy from your food, 425 00:22:26,000 --> 00:22:31,400 as the refrigerant in the evaporator turns from liquid to gas. 426 00:22:31,400 --> 00:22:36,320 Isobutane is so good at extracting heat energy from its surroundings. 427 00:22:36,320 --> 00:22:39,000 If I put a little cup in here with some water, 428 00:22:39,000 --> 00:22:40,360 just a tiny little bit... 429 00:22:42,080 --> 00:22:43,160 ..and I pop it... 430 00:22:43,160 --> 00:22:44,400 Ooh. 431 00:22:44,400 --> 00:22:45,960 SOFT SIZZLING 432 00:22:45,960 --> 00:22:47,160 ..can you hear it? 433 00:22:48,440 --> 00:22:52,920 What's happening here is that the isobutane that is next to the cup 434 00:22:52,920 --> 00:22:56,480 is turning into gas just by touching it. 435 00:22:56,480 --> 00:23:00,240 As a result, the temperature of the water and the cup 436 00:23:00,240 --> 00:23:03,520 are going to drop until eventually... 437 00:23:03,520 --> 00:23:04,840 Oh, my gosh, I think it's happened. 438 00:23:07,080 --> 00:23:08,880 You see the frost there? Look. 439 00:23:08,880 --> 00:23:10,040 Look, look, look, look, look. 440 00:23:11,360 --> 00:23:13,280 All that isobutane has evaporated. 441 00:23:13,280 --> 00:23:15,960 You can see there's none left, right? It's dry on the bottom now. 442 00:23:15,960 --> 00:23:19,080 And all we're left with is a little frosty cup. 443 00:23:19,080 --> 00:23:20,160 Come on, little guy. 444 00:23:21,560 --> 00:23:23,440 It's a teeny tiny ice cube. 445 00:23:25,440 --> 00:23:27,520 Oh, it's got to be whisky on ice, doesn't it? 446 00:23:27,520 --> 00:23:29,320 BAGPIPES PLAY 447 00:23:33,360 --> 00:23:35,000 And there you go, look. 448 00:23:35,000 --> 00:23:37,680 The world's teeniest tiny whisky on ice. 449 00:23:39,480 --> 00:23:41,320 Cheers. 450 00:23:41,320 --> 00:23:44,720 Don't expect me to be sober for the rest of the filming today. 451 00:23:44,720 --> 00:23:49,960 Isobutane keeps things effortlessly chilled in many fridges today. 452 00:23:49,960 --> 00:23:51,760 But how did we get here? 453 00:23:56,520 --> 00:24:01,200 Well, it all started in the late 1740s when Scottish doctor 454 00:24:01,200 --> 00:24:05,120 William Cullen realised that ether used to anaesthetise patients 455 00:24:05,120 --> 00:24:07,800 had special cooling powers. 456 00:24:07,800 --> 00:24:10,360 The more heat it absorbs, the quicker it evaporates. 457 00:24:10,360 --> 00:24:12,760 When the spirit vanishes, the hand is left quite cold. 458 00:24:13,800 --> 00:24:18,120 His work showed how liquids that evaporate easily remove heat. 459 00:24:20,200 --> 00:24:23,640 But it took another 100 years for fridge inventors to catch on 460 00:24:23,640 --> 00:24:26,840 and use them in those early cooling systems. 461 00:24:31,760 --> 00:24:35,160 And when they did, it wasn't smooth sailing. 462 00:24:35,160 --> 00:24:39,200 The refrigerants could be flammable and toxic, 463 00:24:39,200 --> 00:24:42,480 and early domestic fridges were very leaky. 464 00:24:43,480 --> 00:24:47,880 Albert Einstein even took time out from quantum mechanics to design 465 00:24:47,880 --> 00:24:51,320 a safer cooling system after reading about a family who'd 466 00:24:51,320 --> 00:24:53,760 been poisoned in their sleep. 467 00:24:53,760 --> 00:24:57,960 Fridges were killer business, and in 1928, 468 00:24:57,960 --> 00:25:02,240 it prompted the American company Frigidaire to act. 469 00:25:02,240 --> 00:25:07,440 They called in their top chemist, Thomas Midgley, to find a solution. 470 00:25:07,440 --> 00:25:10,400 Midgley started off with the periodic table, which apparently 471 00:25:10,400 --> 00:25:13,040 he loved so much that he was rumoured to carry it round with him 472 00:25:13,040 --> 00:25:14,240 at all times. 473 00:25:14,240 --> 00:25:17,720 Now, he knew that all refrigerants at the time were compounds 474 00:25:17,720 --> 00:25:20,920 that were made up from a series of elements that were largely 475 00:25:20,920 --> 00:25:23,120 in this section of the periodic table. 476 00:25:23,120 --> 00:25:27,680 He also knew that flammability of these compounds decreased 477 00:25:27,680 --> 00:25:32,680 as you went from left to right, and toxicity decreased as you go 478 00:25:32,680 --> 00:25:34,520 from bottom to top. 479 00:25:35,600 --> 00:25:39,920 And all of that together pointed towards fluorine 480 00:25:39,920 --> 00:25:43,120 as being a particularly promising candidate. 481 00:25:44,880 --> 00:25:48,800 Midgley set about combining fluorine and related elements 482 00:25:48,800 --> 00:25:51,440 like chlorine with carbon. 483 00:25:51,440 --> 00:25:55,160 After just three days, finding a frontrunner - 484 00:25:55,160 --> 00:25:57,720 dichlorodifluoromethane. 485 00:25:57,720 --> 00:26:00,680 Try saying that after a teeny tiny whisky. 486 00:26:00,680 --> 00:26:05,120 And as refrigerants go, this brand-new compound seemed perfect. 487 00:26:06,280 --> 00:26:10,520 At the 1930 annual meeting of the American Chemical Society, 488 00:26:10,520 --> 00:26:13,600 Midgley decides he wants to show off his new refrigerant 489 00:26:13,600 --> 00:26:14,720 to all of his colleagues. 490 00:26:14,720 --> 00:26:19,800 Now, this guy, he's quite the showman, and he is deeply invested 491 00:26:19,800 --> 00:26:21,520 in the success of his invention. 492 00:26:21,520 --> 00:26:25,520 And so he gets to the stage with a vial of the stuff and also 493 00:26:25,520 --> 00:26:27,800 a candle, which he then lights. 494 00:26:30,520 --> 00:26:32,320 Now, to really prove a point, 495 00:26:32,320 --> 00:26:35,120 Midgley then pours the vial into a bowl... 496 00:26:36,320 --> 00:26:39,320 ..waits for the refrigerant to evaporate, 497 00:26:39,320 --> 00:26:41,800 inhales a great lungful of the stuff... 498 00:26:42,920 --> 00:26:46,440 ..and then turns and exhales to the candle. 499 00:26:47,560 --> 00:26:50,160 In one fell swoop, he has demonstrated that this stuff 500 00:26:50,160 --> 00:26:52,920 is neither toxic nor flammable. 501 00:26:54,120 --> 00:26:56,200 It's marketing genius. 502 00:26:56,200 --> 00:26:59,200 This little can with a button on top is used in hundreds of ways 503 00:26:59,200 --> 00:27:01,800 to make your life easier and more pleasant. 504 00:27:02,960 --> 00:27:07,600 They called it Freon, and it was a roaring commercial success. 505 00:27:07,600 --> 00:27:11,000 Used as cooling agents in the coils of your refrigerators, 506 00:27:11,000 --> 00:27:14,360 Freon does its work by changing from a liquid to a gas. 507 00:27:15,520 --> 00:27:19,560 Its low boiling point, stability, and safety meant it became 508 00:27:19,560 --> 00:27:22,240 the world's most commonly used refrigerant in 509 00:27:22,240 --> 00:27:24,920 air conditioners and fridges. 510 00:27:24,920 --> 00:27:27,560 Freon refrigerants are ideal. 511 00:27:27,560 --> 00:27:29,880 They've helped the entire refrigeration industry grow 512 00:27:29,880 --> 00:27:31,520 into a $2 billion business. 513 00:27:33,000 --> 00:27:36,120 It was the first of a new class of chemical called 514 00:27:36,120 --> 00:27:38,800 chlorofluorocarbons, 515 00:27:38,800 --> 00:27:42,320 otherwise known as CFCs. 516 00:27:42,320 --> 00:27:44,160 Better things for better living... 517 00:27:45,240 --> 00:27:46,440 ..through chemistry. 518 00:27:49,240 --> 00:27:53,520 It was in the 1980s, once CFCs had made their way into almost 519 00:27:53,520 --> 00:27:55,560 all of the fridges on Earth, 520 00:27:55,560 --> 00:27:58,600 that a young scientist discovered there was a problem. 521 00:28:00,200 --> 00:28:04,320 If we took all the ozone from above us down to this lab, 522 00:28:04,320 --> 00:28:08,640 I'd have a layer of pure ozone just three millimetres thick. 523 00:28:08,640 --> 00:28:11,360 Meet Jon Shanklin 524 00:28:11,360 --> 00:28:13,760 of the British Antarctic Survey. 525 00:28:13,760 --> 00:28:17,000 For almost 50 years, he has been monitoring the health 526 00:28:17,000 --> 00:28:18,360 of the ozone layer. 527 00:28:19,480 --> 00:28:22,600 Between 10 and 25 miles above the Earth in what's called 528 00:28:22,600 --> 00:28:25,040 the stratosphere is a belt of ozone. 529 00:28:25,040 --> 00:28:28,200 If it wasn't for this protective layer, our planet would be a place 530 00:28:28,200 --> 00:28:31,240 of uninhabitable extremes of hot and cold. 531 00:28:32,640 --> 00:28:36,520 Until the 1970s, people assumed that there was nothing we could do 532 00:28:36,520 --> 00:28:41,360 to destroy ozone, which is kind of like the Earth's sunscreen. 533 00:28:41,360 --> 00:28:46,120 But then some theoretical chemists realised that, with time, 534 00:28:46,120 --> 00:28:50,160 CFCs might interact with ozone to reduce the amount 535 00:28:50,160 --> 00:28:51,680 in the ozone layer. 536 00:28:51,680 --> 00:28:55,720 Recent theoretical tests appear to show when the fluorocarbon hits 537 00:28:55,720 --> 00:29:00,360 the ozone layer - first, it breaks down, and when it breaks down, 538 00:29:00,360 --> 00:29:02,600 it releases chlorine atoms. 539 00:29:02,600 --> 00:29:05,760 The chlorine atoms attack and destroy the ozone. 540 00:29:06,840 --> 00:29:10,480 At that point, it was only sort of hints that the chemistry 541 00:29:10,480 --> 00:29:12,080 might support that. 542 00:29:12,080 --> 00:29:14,560 It was by no means proven theory. 543 00:29:15,920 --> 00:29:18,720 The only way to prove it would be to show the ozone layer 544 00:29:18,720 --> 00:29:20,560 was getting thinner. 545 00:29:20,560 --> 00:29:24,320 When I joined the survey, quite a big backlog of observations 546 00:29:24,320 --> 00:29:25,640 had built up. 547 00:29:25,640 --> 00:29:28,520 This was the data that Jon needed. 548 00:29:28,520 --> 00:29:31,720 And in analysing it, he realised the most recent ozone levels 549 00:29:31,720 --> 00:29:33,880 were much lower than expected. 550 00:29:34,960 --> 00:29:38,880 Once you can demonstrate a consistent trend, 551 00:29:38,880 --> 00:29:43,160 then either it's the instrument failing, or it's something that's 552 00:29:43,160 --> 00:29:45,840 going on in the atmosphere. 553 00:29:45,840 --> 00:29:49,960 The ozone data had been captured in Antarctica, and so Jon went 554 00:29:49,960 --> 00:29:51,320 there to investigate. 555 00:29:51,320 --> 00:29:54,800 I was convinced that the observations had been made 556 00:29:54,800 --> 00:29:58,280 correctly in Antarctica, that my calculations were right, 557 00:29:58,280 --> 00:30:00,600 and that something was going on. 558 00:30:01,960 --> 00:30:06,040 To find out if the ozone layer was in the danger he feared, 559 00:30:06,040 --> 00:30:08,600 Jon decided to go further back, 560 00:30:08,600 --> 00:30:12,360 to analyse all ozone data they'd ever collected. 561 00:30:15,040 --> 00:30:19,160 I'm quite bloody-minded, and once I've got my teeth into something, 562 00:30:19,160 --> 00:30:21,000 I don't really want to let it go. 563 00:30:21,000 --> 00:30:24,720 Plotting each individual year up on the graph seemed the obvious 564 00:30:24,720 --> 00:30:26,240 thing to do. 565 00:30:26,240 --> 00:30:29,920 This must be my original draft paper. 566 00:30:29,920 --> 00:30:33,800 It's written in November 1984. 567 00:30:33,800 --> 00:30:39,520 Between 1957 and up to 1972, you could quite easily draw 568 00:30:39,520 --> 00:30:44,720 a straight line, but thereafter, it's really clear to anybody 569 00:30:44,720 --> 00:30:47,880 that ozone values are dropping, 570 00:30:47,880 --> 00:30:50,600 and you couldn't really disagree with that. 571 00:30:50,600 --> 00:30:54,440 Jon's deep dive into the data revealed that in the space 572 00:30:54,440 --> 00:30:57,280 of just ten years, over Antarctica, 573 00:30:57,280 --> 00:31:00,920 half of the ozone had disappeared. 574 00:31:00,920 --> 00:31:03,840 This was the smoking gun he'd been looking for. 575 00:31:03,840 --> 00:31:05,640 It was really quite exciting, I think, 576 00:31:05,640 --> 00:31:07,760 drawing that final line. 577 00:31:07,760 --> 00:31:10,320 Once I had everything plotted out, 578 00:31:10,320 --> 00:31:12,680 absolutely clear-cut. 579 00:31:12,680 --> 00:31:15,120 That was, "Yeah, I've got it." 580 00:31:16,480 --> 00:31:20,920 Jon's paper, published with his bosses Joe Farman and Brian Gardiner, 581 00:31:20,920 --> 00:31:25,560 alerted the world to the dramatic loss of ozone, 582 00:31:25,560 --> 00:31:29,720 boldly stating that the threat from CFC refrigerants was real. 583 00:31:31,040 --> 00:31:34,120 And then possibly a journalist, possibly a scientist, 584 00:31:34,120 --> 00:31:35,520 "Looks like a hole. 585 00:31:35,520 --> 00:31:37,040 "Oh, Ozone Hole." 586 00:31:38,200 --> 00:31:41,320 And that describes it instantly. 587 00:31:42,680 --> 00:31:46,440 This satellite image shows the hole, coloured blue, as it moves 588 00:31:46,440 --> 00:31:48,200 and changes shape. 589 00:31:48,200 --> 00:31:52,280 There's no doubt that CFCs are destroying the stratospheric ozone 590 00:31:52,280 --> 00:31:54,520 and may be endangering the planet. 591 00:31:56,200 --> 00:31:59,600 Jon's discovery had an immediate impact. 592 00:31:59,600 --> 00:32:01,920 The problem is serious. 593 00:32:01,920 --> 00:32:04,240 Changes are taking place. 594 00:32:04,240 --> 00:32:06,920 And therefore, in the immediate future, we should strive 595 00:32:06,920 --> 00:32:09,240 for international regulations. 596 00:32:09,240 --> 00:32:12,800 Within two years, it was agreed that CFC refrigerants 597 00:32:12,800 --> 00:32:15,080 should be banned worldwide. 598 00:32:16,280 --> 00:32:20,640 One big firm already takes back old fridges and freezers and drains 599 00:32:20,640 --> 00:32:23,720 out the CFC, which is returned for recycling. 600 00:32:23,720 --> 00:32:27,280 They process some 500 fridges and freezers a day. 601 00:32:28,440 --> 00:32:31,840 In the late 1980s, CFCs were replaced with more 602 00:32:31,840 --> 00:32:36,200 ozone-friendly hydrofluorocarbons, or HFCs. 603 00:32:36,200 --> 00:32:37,960 It was great news for the ozone layer, 604 00:32:37,960 --> 00:32:41,480 which has since almost recovered, but bad news, too, 605 00:32:41,480 --> 00:32:46,160 because HFCs are a major cause of climate change. 606 00:32:46,160 --> 00:32:50,240 And so they are being replaced, too, with a new wave of refrigerants 607 00:32:50,240 --> 00:32:54,360 like isobutane that have less of an environmental impact. 608 00:32:58,360 --> 00:33:01,600 Our next component isn't quite so controversial. 609 00:33:03,040 --> 00:33:06,560 Always in control, and with a licence to chill, 610 00:33:06,560 --> 00:33:08,000 it's the thermostat. 611 00:33:13,800 --> 00:33:17,800 And back at fridge school, it seems to be hiding in here. 612 00:33:20,840 --> 00:33:23,280 Smells a bit like stale milk. 613 00:33:23,280 --> 00:33:24,680 May the yanking... 614 00:33:24,680 --> 00:33:26,280 Let me see if I can pull this out. 615 00:33:26,280 --> 00:33:28,760 That's a technical term there. 616 00:33:28,760 --> 00:33:30,120 ..commence. 617 00:33:30,120 --> 00:33:32,720 Oh, that is satisfying. 618 00:33:32,720 --> 00:33:34,600 Oh, hello. 619 00:33:34,600 --> 00:33:35,840 Oh, yeah. 620 00:33:37,600 --> 00:33:38,920 Oh! 621 00:33:38,920 --> 00:33:41,320 This is it, then. Thermostat. 622 00:33:41,320 --> 00:33:43,080 This one's a lot bigger than you would find 623 00:33:43,080 --> 00:33:44,360 in a more modern fridge, 624 00:33:44,360 --> 00:33:48,400 but this old gal still has a pretty smart way to control the cold. 625 00:33:50,720 --> 00:33:55,640 It uses this quite clever little trick that is hidden inside here. 626 00:33:55,640 --> 00:33:56,800 If I smash it open? 627 00:33:57,960 --> 00:33:59,040 Yeah, let's do that. 628 00:33:59,040 --> 00:34:00,680 Look, I'm about to get excited. 629 00:34:00,680 --> 00:34:02,080 Oh, my gosh, look at it. 630 00:34:02,080 --> 00:34:03,400 I'm so determined. 631 00:34:03,400 --> 00:34:06,680 But I really want to show you... SHE CACKLES 632 00:34:06,680 --> 00:34:09,040 Look at this! 633 00:34:09,040 --> 00:34:10,840 Look! OK. 634 00:34:10,840 --> 00:34:12,320 ..just how cool this is. 635 00:34:12,320 --> 00:34:14,480 All right, that's legit exciting. 636 00:34:15,800 --> 00:34:17,360 Kind of want to get in there, don't we? 637 00:34:19,320 --> 00:34:21,320 SHE LAUGHS 638 00:34:21,320 --> 00:34:24,160 I know it's really pathetic, but I'm really excited. 639 00:34:24,160 --> 00:34:25,520 Oh, yes. 640 00:34:25,520 --> 00:34:26,800 Hello. 641 00:34:26,800 --> 00:34:28,320 And we're in. 642 00:34:29,840 --> 00:34:31,840 This wire here, then. 643 00:34:31,840 --> 00:34:34,840 So this is tucked in to the coldest bit of your fridge. 644 00:34:34,840 --> 00:34:37,960 This is monitoring the temperature inside. 645 00:34:37,960 --> 00:34:41,600 It actually contains a tiny amount of refrigerant. 646 00:34:41,600 --> 00:34:46,720 And this will expand or contract depending on the temperature. 647 00:34:46,720 --> 00:34:48,880 Kind of comes up through here... 648 00:34:48,880 --> 00:34:53,080 ..where it either pushes or pulls on a teeny tiny set of bellows 649 00:34:53,080 --> 00:34:56,960 that then makes or breaks an electric circuit. 650 00:34:56,960 --> 00:35:01,400 This is like a physical switch that is responding to the temperature 651 00:35:01,400 --> 00:35:03,840 inside the fridge, 652 00:35:03,840 --> 00:35:07,720 switching on or off the cooling system. 653 00:35:07,720 --> 00:35:10,480 When you turn the dial, what you're doing 654 00:35:10,480 --> 00:35:13,200 is you're physically changing 655 00:35:13,200 --> 00:35:16,720 the point at which this circuit closes. 656 00:35:16,720 --> 00:35:20,800 It's how you set just how cold you want the fridge to be, 657 00:35:20,800 --> 00:35:23,880 simply by using the dial. 658 00:35:23,880 --> 00:35:27,960 I mean, that's, like, just so delightful, isn't it? 659 00:35:29,400 --> 00:35:32,760 So how did we come up with this little beauty 660 00:35:32,760 --> 00:35:36,280 that automatically turns the cooling system on and off 661 00:35:36,280 --> 00:35:39,320 to make sure that the temperature stays constant? 662 00:35:40,840 --> 00:35:44,160 Well, it all started in a time before fridges, 663 00:35:44,160 --> 00:35:46,840 when our diet was determined by the seasons 664 00:35:46,840 --> 00:35:51,400 and if you're a fan of chicken, the friskiness of your fowl. 665 00:35:51,400 --> 00:35:55,880 In about the 1600s, people realised that chickens had this potential 666 00:35:55,880 --> 00:36:00,080 to be cheap and filling food for a lot of the population. 667 00:36:00,080 --> 00:36:04,160 The only problem was that producing enough of them 668 00:36:04,160 --> 00:36:06,200 proved to be quite a challenge. 669 00:36:07,360 --> 00:36:08,600 Excuse me, girls. 670 00:36:10,200 --> 00:36:12,360 Oh, she's lovely! 671 00:36:12,360 --> 00:36:14,720 Look at that. 672 00:36:14,720 --> 00:36:17,520 I feel like we're sort of matching. 673 00:36:17,520 --> 00:36:18,680 Do you know what I mean? 674 00:36:20,000 --> 00:36:23,080 For a fertilised egg to turn into a chicken you can eat, 675 00:36:23,080 --> 00:36:26,840 it has to be sat on by a broody hen and kept perfectly warm 676 00:36:26,840 --> 00:36:29,120 for 21 days straight. 677 00:36:29,120 --> 00:36:30,960 Come on, girls. 678 00:36:30,960 --> 00:36:34,920 Various ways to incubate eggs artificially had been tried. 679 00:36:36,000 --> 00:36:37,840 Hello, girlie. 680 00:36:37,840 --> 00:36:40,840 Oh! Is it OK if I have your eggs? 681 00:36:40,840 --> 00:36:44,800 But on the whole, nothing beats what nature had intended. 682 00:36:47,480 --> 00:36:52,120 Ideally, you want something that can replicate the precise 683 00:36:52,120 --> 00:36:55,200 and constant temperature of a hen's bum. 684 00:36:58,840 --> 00:37:01,360 Bear in mind that in the 1600s, 685 00:37:01,360 --> 00:37:05,240 cutting-edge science was served up by royal court magicians... 686 00:37:06,920 --> 00:37:10,080 ..and there was none more famous than Cornelis Drebbel. 687 00:37:12,200 --> 00:37:14,920 So this guy, Drebbel, he's a prolific inventor. 688 00:37:14,920 --> 00:37:19,240 He comes up with a submarine, a perpetual motion machine, 689 00:37:19,240 --> 00:37:22,640 and then he decides to take on the chicken production problem 690 00:37:22,640 --> 00:37:25,600 by having a crack at the world's first thermostat. 691 00:37:26,880 --> 00:37:28,440 And as if by magic... 692 00:37:29,720 --> 00:37:31,240 ..here it is. 693 00:37:31,240 --> 00:37:32,680 Look at that! 694 00:37:32,680 --> 00:37:34,680 We have created an... 695 00:37:34,680 --> 00:37:38,600 HESITATING: ..exact replica of the thermostat mechanism that controlled 696 00:37:38,600 --> 00:37:42,680 the temperature of Drebbel's ingenious egg incubating machine - 697 00:37:42,680 --> 00:37:44,800 with just one slight difference. 698 00:37:44,800 --> 00:37:47,200 So here we have a heat lamp. 699 00:37:47,200 --> 00:37:50,600 Now, in Drebbel's case, obviously before the discovery of electricity, 700 00:37:50,600 --> 00:37:53,080 this would have been a fire instead. 701 00:37:53,080 --> 00:37:54,560 Let me just switch this on here. 702 00:37:55,840 --> 00:37:58,880 This tube is filled with flammable alcohol, 703 00:37:58,880 --> 00:38:02,600 so we decided to keep fire out of the mix this time. 704 00:38:02,600 --> 00:38:04,160 Oh, that is nice and warm, isn't it? 705 00:38:04,160 --> 00:38:06,520 You have to imagine, then, that you've got your eggs 706 00:38:06,520 --> 00:38:08,080 in a little container just here, 707 00:38:08,080 --> 00:38:11,640 and this tube here is monitoring the temperature. 708 00:38:13,080 --> 00:38:15,560 Instead of a hen keeping them warm, 709 00:38:15,560 --> 00:38:19,960 the eggs are surrounded by a water bath, warmed by the fire. 710 00:38:19,960 --> 00:38:23,040 And the tube containing alcohol sits in the water too, 711 00:38:23,040 --> 00:38:24,880 warming up alongside it. 712 00:38:26,760 --> 00:38:31,800 Alcohol expands as it gets warmer, and so as it expands, 713 00:38:31,800 --> 00:38:36,560 it pushes down this tube all the way round to the bottom here. 714 00:38:36,560 --> 00:38:41,040 Sitting in the bottom of this U-bend is some mercury, 715 00:38:41,040 --> 00:38:43,800 which feels the pressure from the alcohol. 716 00:38:43,800 --> 00:38:46,960 In turn, the mercury moves through the tube, 717 00:38:46,960 --> 00:38:51,240 and as it's so dense, it creates a lot of upwards force. 718 00:38:53,320 --> 00:38:56,680 Now, here we have this sort of... It's like a cork, basically, 719 00:38:56,680 --> 00:38:59,200 with a pin stuck in it. 720 00:38:59,200 --> 00:39:01,480 And slowly, slowly, slowly, 721 00:39:01,480 --> 00:39:04,360 as this bit here warms up and expands, 722 00:39:04,360 --> 00:39:08,000 this pin is going to move upwards, 723 00:39:08,000 --> 00:39:12,080 until eventually, the magnet stuck to it 724 00:39:12,080 --> 00:39:15,280 is going to switch off the heat lamp. 725 00:39:15,280 --> 00:39:17,160 In Drebbel's device, 726 00:39:17,160 --> 00:39:19,840 the pin pushed up onto a damper 727 00:39:19,840 --> 00:39:22,920 that controlled airflow needed for the fire to burn. 728 00:39:24,480 --> 00:39:28,760 I sort of feel like it is moving very, very slowly. 729 00:39:30,120 --> 00:39:32,280 Look, can you see now how it's slightly lower 730 00:39:32,280 --> 00:39:34,280 on this side than that side? 731 00:39:34,280 --> 00:39:38,080 The temperature rises, the alcohol expands 732 00:39:38,080 --> 00:39:39,840 and pushes the mercury up. 733 00:39:40,840 --> 00:39:42,400 Here we go. 734 00:39:42,400 --> 00:39:45,720 It's getting super, super close. 735 00:39:45,720 --> 00:39:47,320 It's going to switch. 736 00:39:47,320 --> 00:39:49,400 Oh! 737 00:39:49,400 --> 00:39:51,000 No boiled eggs for us. 738 00:39:53,640 --> 00:39:57,000 In the same way, when Drebbel's incubator got too hot... 739 00:39:58,320 --> 00:40:01,000 ..the damper closed, quelling the flames 740 00:40:01,000 --> 00:40:03,760 and cooling everything down a little. 741 00:40:03,760 --> 00:40:08,760 The mercury would then fall until the damper opened again 742 00:40:08,760 --> 00:40:10,640 and the fire was stoked. 743 00:40:14,480 --> 00:40:17,440 This is now perfectly self-regulating. 744 00:40:17,440 --> 00:40:21,440 It heats up, turns off, cools down, turns on. 745 00:40:21,440 --> 00:40:25,480 You can leave this be and come back when your chickens are hatched. 746 00:40:25,480 --> 00:40:27,760 Chicken problem? 747 00:40:27,760 --> 00:40:29,680 What chicken problem? 748 00:40:29,680 --> 00:40:32,240 Well, it wasn't quite solved, 749 00:40:32,240 --> 00:40:35,360 because Drebbel's thermostatically-controlled incubator 750 00:40:35,360 --> 00:40:37,840 was way ahead of its time. 751 00:40:37,840 --> 00:40:42,440 And as far as we know, no-one ever managed to reproduce it. 752 00:40:42,440 --> 00:40:46,240 You have to imagine, right, Drebbel was doing this at a time when 753 00:40:46,240 --> 00:40:49,280 most of the physics of what's going on here 754 00:40:49,280 --> 00:40:51,520 was yet to be discovered, right? 755 00:40:51,520 --> 00:40:55,440 No idea about thermal expansion, no idea about hydraulics. 756 00:40:55,440 --> 00:40:59,160 And then tune it perfectly 757 00:40:59,160 --> 00:41:01,720 to the precise temperature of a chicken's bum. 758 00:41:01,720 --> 00:41:07,560 It is absurd that he was able to successfully do this in the 1600s. 759 00:41:09,480 --> 00:41:12,360 In fact, it took over 200 years 760 00:41:12,360 --> 00:41:15,760 for a thermostat using the same principles to be patented. 761 00:41:17,840 --> 00:41:22,600 The spectacularly-named Damper Flapper automatically controlled 762 00:41:22,600 --> 00:41:26,480 the temperature in early home central heating systems. 763 00:41:26,480 --> 00:41:30,200 And 100 years later, it inspired the design of the first 764 00:41:30,200 --> 00:41:33,360 modern mechanical fridge thermostats, 765 00:41:33,360 --> 00:41:34,760 like this one. 766 00:41:38,440 --> 00:41:40,840 Today, the team in Bosch's development lab 767 00:41:40,840 --> 00:41:44,800 are giving the thermostat a 21st-century upgrade. 768 00:41:46,720 --> 00:41:48,200 The compressor is our heart 769 00:41:48,200 --> 00:41:51,160 and the thermostat and our electronics are the brain. 770 00:41:51,160 --> 00:41:54,200 Oh, nice. And they are connecting with each other. 771 00:41:54,200 --> 00:41:56,760 That is Inaki Sola, 772 00:41:56,760 --> 00:41:59,760 master of modern thermostatic magic. 773 00:42:01,200 --> 00:42:04,200 This was state of the art, but 20 years ago. Mm-hm. 774 00:42:04,200 --> 00:42:05,800 Now what's the state of the art? 775 00:42:05,800 --> 00:42:07,520 Look at the size. Mm-hm. 776 00:42:08,800 --> 00:42:13,000 This is the same function you see over there, in this big part. Yeah. 777 00:42:13,000 --> 00:42:14,800 This electrical one. 778 00:42:14,800 --> 00:42:16,720 And what happens, we have here, a resistance. 779 00:42:16,720 --> 00:42:21,240 Yeah. And this is changing the electricity moving into this cable. 780 00:42:21,240 --> 00:42:24,160 So, wait, this is just like a thermometer, is it? Yeah. 781 00:42:25,560 --> 00:42:29,200 By detecting changes in the flow of electricity in this cable, 782 00:42:29,200 --> 00:42:31,960 the temperature can be quickly and accurately measured 783 00:42:31,960 --> 00:42:36,280 here at the top of the fridge and converted into a digital signal. 784 00:42:36,280 --> 00:42:38,720 So you've gone from mechanical to digital. 785 00:42:38,720 --> 00:42:39,960 Exactly. 786 00:42:39,960 --> 00:42:43,840 But with a digital signal, this fridge's brainy thermostat 787 00:42:43,840 --> 00:42:46,240 can do some cool new things. 788 00:42:46,240 --> 00:42:49,440 Right, let's imagine... Yeah. ..that I come in and I'm like, 789 00:42:49,440 --> 00:42:51,840 right, I've cooked a really big stew. 790 00:42:51,840 --> 00:42:53,840 Yeah. Irish, thank you. 791 00:42:53,840 --> 00:42:56,600 And I've just put it in there. Very irresponsible. 792 00:42:56,600 --> 00:42:58,360 I've put it in there while it's still hot. 793 00:42:58,360 --> 00:42:59,680 Yeah. The fridge can tell? 794 00:42:59,680 --> 00:43:01,120 Yeah. It can tell? 795 00:43:01,120 --> 00:43:04,000 Yes. You put the stuff here. It's really, really hot. 796 00:43:04,000 --> 00:43:07,120 This warm air goes to the thermostat, to this. Yeah. 797 00:43:07,120 --> 00:43:10,960 And this means, he's realised, "Oh, something changed." Mm-hm. 798 00:43:10,960 --> 00:43:13,840 And it sends a signal to the brain, our electronic and say, 799 00:43:13,840 --> 00:43:16,120 "Hey, compressor, start running." 800 00:43:16,120 --> 00:43:18,880 The super smart bit is what happens next. 801 00:43:18,880 --> 00:43:22,840 We are able to control the flow, the air flow circulation, 802 00:43:22,840 --> 00:43:27,480 and then the cold air distributed by this fan unit 803 00:43:27,480 --> 00:43:29,720 will start flowing all round... Mm-hm. 804 00:43:29,720 --> 00:43:32,880 ..ensuring that when you set here, for example, +6 degrees, 805 00:43:32,880 --> 00:43:34,760 you have everywhere six degrees. 806 00:43:34,760 --> 00:43:35,800 Oh! Yeah. 807 00:43:36,880 --> 00:43:40,040 Bosch's robots test their smart thermostat 808 00:43:40,040 --> 00:43:42,400 and airflow control to the max. 809 00:43:42,400 --> 00:43:44,760 Whether it's shoving in warm leftovers 810 00:43:44,760 --> 00:43:47,520 or keeping the door open for ages, 811 00:43:47,520 --> 00:43:51,360 they simulate the lot to make sure the entire fridge 812 00:43:51,360 --> 00:43:55,920 stays within 0.5 degrees of the temperature we choose... 813 00:43:55,920 --> 00:43:57,960 ..with one exception. 814 00:43:57,960 --> 00:44:01,680 So you see here you can choose from two to eight degrees, 815 00:44:01,680 --> 00:44:04,280 but here, it will always stay close to zero. 816 00:44:04,280 --> 00:44:06,200 Why do you want that? 817 00:44:06,200 --> 00:44:07,720 I will show it to you. Yeah, go on. 818 00:44:07,720 --> 00:44:10,200 Same appliance. Touch this. 819 00:44:10,200 --> 00:44:12,760 Oh, hello! Some stunt veg. 820 00:44:12,760 --> 00:44:14,360 How long has that been in there? 821 00:44:14,360 --> 00:44:17,040 That is a manky carrot! Almost four or five days. 822 00:44:17,040 --> 00:44:18,280 Four or five days?! 823 00:44:18,280 --> 00:44:19,920 Yeah. And now compare it with that. 824 00:44:22,680 --> 00:44:24,640 Did you really put these in at the same time? 825 00:44:24,640 --> 00:44:26,520 We bought them both the same day. 826 00:44:26,520 --> 00:44:29,680 OK. And then, wait. But then there's also the salad. 827 00:44:29,680 --> 00:44:31,720 Yeah, the salad is also here. It's also the same. 828 00:44:32,840 --> 00:44:34,960 So you can compare them. 829 00:44:34,960 --> 00:44:36,560 And people are not aware about that. 830 00:44:37,680 --> 00:44:41,080 By varying the temperature in different sections of the fridge, 831 00:44:41,080 --> 00:44:44,320 smart thermostats in many modern fridges 832 00:44:44,320 --> 00:44:46,800 don't only save you from veg wilt, 833 00:44:46,800 --> 00:44:51,720 they also allow the fridge to use less energy, saving us cash. 834 00:44:51,720 --> 00:44:56,640 I've got to be honest with you, I have never once adhered 835 00:44:56,640 --> 00:44:58,760 to the pictures on the drawers. 836 00:44:58,760 --> 00:45:00,680 I know. It's our pain. 837 00:45:00,680 --> 00:45:04,320 I thought it was just like, you know, hey, helpful suggestion! 838 00:45:04,320 --> 00:45:06,120 This is, like, a cute-sized drawer. 839 00:45:06,120 --> 00:45:08,920 I didn't realise you were designing the entire thing to be perfect. 840 00:45:08,920 --> 00:45:11,960 But this is really important. You should really take care of that. 841 00:45:11,960 --> 00:45:14,480 All right. I'm going to go rearrange my fridge when I get home. 842 00:45:14,480 --> 00:45:15,800 Yeah. 843 00:45:14,480 --> 00:45:15,800 THEY LAUGH 844 00:45:17,520 --> 00:45:20,760 May we now consider ourselves officially schooled 845 00:45:20,760 --> 00:45:22,760 in proper fridge usage. 846 00:45:26,760 --> 00:45:30,720 With so many bits dedicated to hoofing heat out, 847 00:45:30,720 --> 00:45:34,320 it's time for the component that stops it getting back in. 848 00:45:34,320 --> 00:45:36,360 Quietly crucial, 849 00:45:36,360 --> 00:45:40,080 hiding just beneath your fridge's shiny shell. 850 00:45:40,080 --> 00:45:41,120 It's... 851 00:45:42,280 --> 00:45:43,680 ..the insulation. 852 00:45:47,640 --> 00:45:51,400 Remember all that stuff I was hacking away at earlier on? 853 00:45:51,400 --> 00:45:53,840 This is the insulation, 854 00:45:53,840 --> 00:45:58,080 and it is not there to stop the cold from escaping. 855 00:45:58,080 --> 00:45:59,800 No. We've spoken about this. 856 00:45:59,800 --> 00:46:04,440 It is there to stop the heat from outside getting in. 857 00:46:04,440 --> 00:46:06,800 If I take a little bit of this, 858 00:46:06,800 --> 00:46:10,480 I can show you how it's able to do this under a microscope. 859 00:46:10,480 --> 00:46:14,720 And it's only when you magnify a really thin slice... 860 00:46:14,720 --> 00:46:16,440 Just a little bit of that there. 861 00:46:16,440 --> 00:46:19,560 ..and look at it with a powerful lens... 862 00:46:19,560 --> 00:46:21,720 Look at that. Wow! 863 00:46:21,720 --> 00:46:24,720 ..that you can see just how insulation... 864 00:46:24,720 --> 00:46:25,840 Oh, my gosh! 865 00:46:25,840 --> 00:46:28,440 ..does its insulating thing. 866 00:46:28,440 --> 00:46:32,200 You really can see the plasticky strings that are just encasing 867 00:46:32,200 --> 00:46:35,120 bubble after bubble after bubble after bubble. 868 00:46:35,120 --> 00:46:37,640 And, like, layers and layers and layers of them. 869 00:46:39,120 --> 00:46:42,000 This plasticky material, called a polymer, 870 00:46:42,000 --> 00:46:44,520 is bad at transferring heat energy, 871 00:46:44,520 --> 00:46:47,600 and so is good at insulating your fridge. 872 00:46:47,600 --> 00:46:49,280 But what's more important... 873 00:46:49,280 --> 00:46:52,200 It's, like, almost all bubble. 874 00:46:52,200 --> 00:46:56,400 ..is the unique foamy structure it creates. 875 00:46:56,400 --> 00:47:00,120 All of these bubbles trap air, and when air is trapped, 876 00:47:00,120 --> 00:47:02,320 it can't move heat. 877 00:47:02,320 --> 00:47:04,680 It's almost all air. 878 00:47:04,680 --> 00:47:06,240 That's what you don't realise. 879 00:47:06,240 --> 00:47:10,360 And that is what makes it a good insulator. 880 00:47:12,240 --> 00:47:16,560 And I'd love to show you just how well it keeps heat out of the fridge 881 00:47:16,560 --> 00:47:18,920 by turning these on it. 882 00:47:18,920 --> 00:47:20,600 But unfortunately... 883 00:47:22,080 --> 00:47:26,720 ..foam insulation is quite flammable, so, um, instead... 884 00:47:26,720 --> 00:47:28,600 What, I have to do it? 885 00:47:28,600 --> 00:47:30,360 ..it's tidy-up time. 886 00:47:30,360 --> 00:47:31,680 Have we got a dustpan? 887 00:47:31,680 --> 00:47:32,720 There you go. 888 00:47:34,560 --> 00:47:39,800 So how did we end up with this messy but quite miraculous material? 889 00:47:41,560 --> 00:47:45,360 Well, the insulation used in early fridges was stuff like wool 890 00:47:45,360 --> 00:47:47,320 that naturally trapped air. 891 00:47:49,080 --> 00:47:51,120 ARCHIVE: The cabinet is insulated with pressed cork. 892 00:47:51,120 --> 00:47:54,200 This makes any leakage of heat a very slow process. 893 00:47:54,200 --> 00:47:57,000 Wool and cork were gradually replaced. 894 00:47:57,000 --> 00:47:59,400 The latest insulation material is aluminium foil. 895 00:47:59,400 --> 00:48:01,880 But this was as good as it got... 896 00:48:04,320 --> 00:48:08,840 ..until the 1930s, when the spectre of war... 897 00:48:08,840 --> 00:48:12,800 Our defence programme will be no more than is sufficient. 898 00:48:12,800 --> 00:48:18,640 ..and an accidental experiment began a synthetic insulation revolution. 899 00:48:19,720 --> 00:48:22,560 There are so many different combinations of chemicals 900 00:48:22,560 --> 00:48:24,960 that you can add together to make surprising things. 901 00:48:24,960 --> 00:48:29,200 Meet materials maestro Anna Ploszajski. 902 00:48:29,200 --> 00:48:32,080 And what she doesn't know about these things 903 00:48:32,080 --> 00:48:35,040 is frankly not worth knowing. 904 00:48:35,040 --> 00:48:39,000 Back in the 1930s, World War II about to happen, 905 00:48:39,000 --> 00:48:41,480 trade routes internationally are starting to break down. 906 00:48:41,480 --> 00:48:44,640 Suddenly, lots of countries weren't able to get access 907 00:48:44,640 --> 00:48:47,920 to materials that they're used to, particularly natural rubber. 908 00:48:47,920 --> 00:48:50,680 So there's a big challenge, really, to the chemical community of, 909 00:48:50,680 --> 00:48:52,520 can you make this stuff in the lab? 910 00:48:54,360 --> 00:48:58,600 It's 1937, and at pharmaceutical giant IG Farben, 911 00:48:58,600 --> 00:49:01,920 the challenge falls to a young scientist called Otto Bayer. 912 00:49:02,880 --> 00:49:05,880 He's really interested in this problem of, 913 00:49:05,880 --> 00:49:07,320 can we make a new synthetic rubber? 914 00:49:07,320 --> 00:49:09,640 And one day, he added two chemicals together. 915 00:49:09,640 --> 00:49:11,960 What we now know is that one of those chemicals had 916 00:49:11,960 --> 00:49:14,640 a bit of contaminant in it, which he didn't realise. Oh! 917 00:49:14,640 --> 00:49:18,720 And that contaminant actually made a big, bubbly, foamy mess. Ooh. 918 00:49:18,720 --> 00:49:21,360 And he showed it to some colleagues and they said, 919 00:49:21,360 --> 00:49:25,320 "Otto, we don't need a Swiss cheese." 920 00:49:25,320 --> 00:49:27,000 THEY LAUGH 921 00:49:27,000 --> 00:49:29,440 Oh, poor guy! "We need some rubber." 922 00:49:29,440 --> 00:49:33,080 And so a lot of his colleagues were doubting him, 923 00:49:33,080 --> 00:49:37,160 but he believed in his foams, and so he continued to work on them. 924 00:49:37,160 --> 00:49:39,320 In honour of Bayer's tenacity... 925 00:49:40,560 --> 00:49:43,400 Do I need to worry about my own kitchen here? 926 00:49:43,400 --> 00:49:46,280 Not at this stage. OK. 927 00:49:43,400 --> 00:49:46,280 THEY LAUGH 928 00:49:46,280 --> 00:49:49,920 ..we are going to recreate his accidental discovery 929 00:49:49,920 --> 00:49:53,760 of what today is called polyurethane foam. 930 00:49:53,760 --> 00:49:56,640 How much am I putting in? 35ml. 931 00:49:56,640 --> 00:49:57,840 OK. 932 00:49:57,840 --> 00:50:00,840 Our ingredients are two different liquids 933 00:50:00,840 --> 00:50:03,720 that individually don't do much... 934 00:50:03,720 --> 00:50:06,160 What we're going to do is pour both of these at the same time 935 00:50:06,160 --> 00:50:07,760 into that beaker. OK. 936 00:50:07,760 --> 00:50:10,040 You ready? Yep. Three, two, one. 937 00:50:11,360 --> 00:50:13,320 ..but when combined... 938 00:50:13,320 --> 00:50:15,880 Very good. OK. Now you can stir, stir, stir. OK. 939 00:50:15,880 --> 00:50:18,320 ..it is a different story. 940 00:50:18,320 --> 00:50:20,560 Ooh! It's getting bubbly. Right. So you can see it bubbling 941 00:50:20,560 --> 00:50:23,000 straight away. Yeah. What, are we putting it in that one? 942 00:50:23,000 --> 00:50:26,480 Yeah, it's going to go... Is that how big it's going to go? Yeah. 943 00:50:26,480 --> 00:50:27,920 All right. 944 00:50:29,520 --> 00:50:31,120 Sorry, yeah. Pour it? 945 00:50:33,720 --> 00:50:35,200 OK. I don't believe you. 946 00:50:37,000 --> 00:50:38,760 Oh! And now watch. Come on. It's growing. 947 00:50:39,800 --> 00:50:42,160 HANNAH GASPS 948 00:50:42,160 --> 00:50:44,280 Ta-da! Oh, my goodness. 949 00:50:44,280 --> 00:50:46,480 It looks like when you've over-poured a beer. 950 00:50:47,920 --> 00:50:51,040 Molecules in the two liquids are linking together 951 00:50:51,040 --> 00:50:54,640 into long, stringy polymer chains that can build a solid. 952 00:50:54,640 --> 00:50:57,080 And it is a bubbly one 953 00:50:57,080 --> 00:51:00,400 because in the process, a gas is also released. 954 00:51:01,760 --> 00:51:04,680 OK, I have a strong feeling this could go over the top. 955 00:51:04,680 --> 00:51:07,800 THEY LAUGH 956 00:51:07,800 --> 00:51:09,040 Here it goes. Oh, my gosh. 957 00:51:09,040 --> 00:51:10,880 Oh, my gosh! Shall I catch it? 958 00:51:10,880 --> 00:51:12,120 Yeah, go on. 959 00:51:12,120 --> 00:51:15,160 Looks like... Oh, it's quite warm. HANNAH LAUGHS 960 00:51:15,160 --> 00:51:18,400 It looks like something's being birthed. Oh! 961 00:51:20,640 --> 00:51:22,320 Whoa! 962 00:51:22,320 --> 00:51:27,280 OK, that is the weirdest thing. 963 00:51:22,320 --> 00:51:27,280 THEY LAUGH 964 00:51:27,280 --> 00:51:28,840 Weird, indeed. 965 00:51:28,840 --> 00:51:32,200 And at first, not even Bayer quite knew what to do with it. 966 00:51:33,600 --> 00:51:34,800 I have to be honest with you, 967 00:51:34,800 --> 00:51:38,040 I'm just imagining that day in the lab when he's, like, 968 00:51:38,040 --> 00:51:41,480 pulling out the streams of this stuff in front of his colleagues. 969 00:51:41,480 --> 00:51:44,040 GERMAN ACCENT: "Look, it's a new invention!" 970 00:51:44,040 --> 00:51:46,880 Yeah, I mean, it's fair enough they weren't that impressed. It is. 971 00:51:49,240 --> 00:51:52,080 Just a couple of years later, 972 00:51:52,080 --> 00:51:54,800 war broke out, and the company IG Farben 973 00:51:54,800 --> 00:51:59,040 became a central participant in the Nazi killing machine. 974 00:52:00,960 --> 00:52:03,800 It would be another ten years, long after the war... 975 00:52:06,280 --> 00:52:11,000 ..that the potential of Otto's discovery would be realised. 976 00:52:11,000 --> 00:52:13,880 ARCHIVE: Science presents a new synthetic sensation. 977 00:52:13,880 --> 00:52:16,000 It's the world's lightest solid. 978 00:52:17,400 --> 00:52:22,000 In the early 1950s, polyurethane foam took off. 979 00:52:22,000 --> 00:52:23,880 As an insulating material for houses, 980 00:52:23,880 --> 00:52:25,680 refrigerators and aeroplanes. 981 00:52:25,680 --> 00:52:29,280 With tweaks to the recipe, it could be mass manufactured. 982 00:52:29,280 --> 00:52:32,040 This machine produces polyurethane foam. 983 00:52:32,040 --> 00:52:35,680 In a soft and squishy form for home furnishings, 984 00:52:35,680 --> 00:52:39,360 or light and rigid enough to hit the surf... 985 00:52:39,360 --> 00:52:43,560 Clamped on either side are blocks of stiff polyurethane foam. 986 00:52:43,560 --> 00:52:48,040 ..its insulation powers were so good that it even took us to the moon. 987 00:52:49,200 --> 00:52:50,840 Magnificent desolation. 988 00:52:52,040 --> 00:52:54,040 As the cooling industry boomed, 989 00:52:54,040 --> 00:52:57,280 it would become the only choice for fridge insulation. 990 00:53:00,480 --> 00:53:02,680 And today, it's what beats the heat 991 00:53:02,680 --> 00:53:05,800 in nearly all of the world's household fridges. 992 00:53:12,840 --> 00:53:15,920 So where does the fridge go from here? 993 00:53:18,200 --> 00:53:19,840 Well, the next big breakthrough 994 00:53:19,840 --> 00:53:23,560 could change how its innards work forever, 995 00:53:23,560 --> 00:53:28,680 because the future looks rather more magnetic. 996 00:53:31,320 --> 00:53:35,280 For over 100 years, the humble fridge has been chugging away, 997 00:53:35,280 --> 00:53:37,960 brilliantly keeping stuff cold. 998 00:53:37,960 --> 00:53:40,560 But there is a cost. 999 00:53:40,560 --> 00:53:44,440 The 200 million fridges bought worldwide each year 1000 00:53:44,440 --> 00:53:48,360 are big, resource-heavy beasts, and much of their materials, 1001 00:53:48,360 --> 00:53:50,800 from the insulation to the refrigerant, 1002 00:53:50,800 --> 00:53:53,920 take their toll on our rapidly warming planet. 1003 00:53:55,040 --> 00:53:57,240 So what if there was a greener way to chill? 1004 00:53:58,680 --> 00:54:02,120 There are three billion cooling appliances in operation today, 1005 00:54:02,120 --> 00:54:04,840 and that's going to grow to over ten billion by 2050. 1006 00:54:04,840 --> 00:54:07,520 So this is an enormous industry. 1007 00:54:07,520 --> 00:54:10,160 That is Neil Wilson. 1008 00:54:10,160 --> 00:54:12,720 From this unassuming workshop in Milton Keynes, 1009 00:54:12,720 --> 00:54:16,360 his company are developing a radical new fridge, 1010 00:54:16,360 --> 00:54:19,920 built from recyclable materials and, crucially, without 1011 00:54:19,920 --> 00:54:22,840 the most problematic component. 1012 00:54:22,840 --> 00:54:24,160 When we began the company, 1013 00:54:24,160 --> 00:54:26,880 we really were worried about the refrigerant gases. 1014 00:54:26,880 --> 00:54:29,160 They're a lot better than they used to be, though, aren't they? 1015 00:54:29,160 --> 00:54:30,280 Are they still problematic? 1016 00:54:30,280 --> 00:54:32,960 There's an enormous amount of HFC still used, 1017 00:54:32,960 --> 00:54:34,600 and that drives global warming. 1018 00:54:34,600 --> 00:54:38,560 And even many of the alternatives are flammable or explosive or toxic. 1019 00:54:38,560 --> 00:54:40,360 So you want to change that? We want to change that. 1020 00:54:40,360 --> 00:54:41,880 We want to bring in a new technology 1021 00:54:41,880 --> 00:54:44,080 that doesn't use refrigerant gases at all. 1022 00:54:45,080 --> 00:54:47,360 It might not look like the future of refrigeration, 1023 00:54:47,360 --> 00:54:51,520 but Neil's alternative is this small piece of metal on the end of a stick. 1024 00:54:52,680 --> 00:54:55,480 Now, this material has one special property. 1025 00:54:55,480 --> 00:54:58,360 When it goes into a magnetic field, it changes temperature. 1026 00:54:58,360 --> 00:54:59,800 I'm going to put it into the field. 1027 00:54:59,800 --> 00:55:00,840 It's gone up! 1028 00:55:01,920 --> 00:55:04,280 Oh, loads! A couple of degrees. So it warmed up. Yeah. 1029 00:55:04,280 --> 00:55:07,960 And now the heat that was generated, that's just now dissipating. 1030 00:55:07,960 --> 00:55:10,760 So now when you pull it out, what happens? 1031 00:55:10,760 --> 00:55:12,560 So now... It dropped! It's gone down. 1032 00:55:12,560 --> 00:55:14,320 You're cheating physics! 1033 00:55:14,320 --> 00:55:16,160 There's no cheating at all. Nothing's touched it, 1034 00:55:16,160 --> 00:55:18,040 and it's gone down in temperature. 1035 00:55:18,040 --> 00:55:19,520 It's not actually cheating. 1036 00:55:19,520 --> 00:55:23,440 The metal cools because of the way magnets affect the energy 1037 00:55:23,440 --> 00:55:26,320 of the tiny little electrons. 1038 00:55:26,320 --> 00:55:28,680 When we put it into the magnetic field, 1039 00:55:28,680 --> 00:55:31,280 the electrons, which were just buzzing around... 1040 00:55:31,280 --> 00:55:33,400 Having a nice old time. ..having a nice old time, 1041 00:55:33,400 --> 00:55:35,400 suddenly are in this ordered state. 1042 00:55:35,400 --> 00:55:37,640 A bit like a musical statue, they stop. 1043 00:55:37,640 --> 00:55:39,800 So that energy gets transferred into the metal, 1044 00:55:39,800 --> 00:55:41,240 and so the metal warms up. 1045 00:55:41,240 --> 00:55:44,720 And then when it comes out, the heat goes out into the room, 1046 00:55:44,720 --> 00:55:47,400 meaning that ends up getting colder. Precisely. 1047 00:55:47,400 --> 00:55:49,440 That is cool. 1048 00:55:49,440 --> 00:55:52,480 I'm extremely impressed by this, but you're only getting down to 1049 00:55:52,480 --> 00:55:56,680 about 20 degrees, and that is still too warm for milk to not go off. 1050 00:55:56,680 --> 00:55:59,480 Absolutely. So the material is key, but we need to engineer it 1051 00:55:59,480 --> 00:56:03,200 into a device that effectively amplifies the effect. 1052 00:56:03,200 --> 00:56:05,880 The solution is surprisingly simple - 1053 00:56:05,880 --> 00:56:09,440 take a bunch of these bits of magic metal, stack them up, 1054 00:56:09,440 --> 00:56:12,960 and get a great big magnet spinning around them. 1055 00:56:12,960 --> 00:56:15,840 This allows us to create a continuous cooling process. 1056 00:56:15,840 --> 00:56:18,360 Got you. So at any point in time, some of the materials are 1057 00:56:18,360 --> 00:56:20,080 going into the magnetic field, 1058 00:56:20,080 --> 00:56:21,720 and at the same time, some is coming out. 1059 00:56:21,720 --> 00:56:23,320 I see. So you're continuously driving 1060 00:56:23,320 --> 00:56:25,240 this heating and cooling of the material. 1061 00:56:25,240 --> 00:56:29,360 What we have flowing around our loop is essentially water. 1062 00:56:29,360 --> 00:56:32,920 So you've basically got the water doing kind of the same journey... 1063 00:56:32,920 --> 00:56:35,640 Kind of, yes. ..as the refrigerant gas does in a bog-standard fridge, 1064 00:56:35,640 --> 00:56:38,920 moving the energy around. Absolutely. 1065 00:56:38,920 --> 00:56:40,200 I can start the magnet spinning. 1066 00:56:41,640 --> 00:56:43,480 Then turn on the pump. 1067 00:56:44,880 --> 00:56:46,880 The cold loop that was sitting at room temperature, 1068 00:56:46,880 --> 00:56:49,680 that'll cool down to around four or five degrees. 1069 00:56:49,680 --> 00:56:52,360 Fridge temperature. Milk temperature, yes. 1070 00:56:52,360 --> 00:56:54,440 You should now be able to feel this loop getting cold. 1071 00:56:55,760 --> 00:56:57,320 Ooh! 1072 00:56:57,320 --> 00:56:58,960 If it was inside an insulated box, 1073 00:56:58,960 --> 00:57:01,760 it would cool the box down a bit colder. 1074 00:57:01,760 --> 00:57:03,680 Amazing. 1075 00:57:03,680 --> 00:57:06,200 Can you just pop this in the bottom of a fridge, then? 1076 00:57:06,200 --> 00:57:08,400 Yes. This has actually been designed to fit 1077 00:57:08,400 --> 00:57:10,400 into a standard mass-produced fridge. 1078 00:57:11,720 --> 00:57:15,880 It's still early days, but Neil has developed a commercial version 1079 00:57:15,880 --> 00:57:19,400 and is also working with a domestic fridge manufacturer. 1080 00:57:21,360 --> 00:57:25,120 It may be that soon the tech that makes our fridges tick 1081 00:57:25,120 --> 00:57:27,480 will look fundamentally different... 1082 00:57:29,080 --> 00:57:33,160 ..but the fact that it has remained largely unchanged for 100 years 1083 00:57:33,160 --> 00:57:37,080 shows just what an extraordinary invention this is. 1084 00:57:37,080 --> 00:57:39,320 The thing I can't get over is this idea that 1085 00:57:39,320 --> 00:57:42,320 if you lived in a hot country before any of this happened, 1086 00:57:42,320 --> 00:57:45,320 you would never have experienced anything cold, 1087 00:57:45,320 --> 00:57:49,360 because there are strict rules to physics that cannot be broken. 1088 00:57:49,360 --> 00:57:53,000 You cannot move energy to where it does not want to be moved, 1089 00:57:53,000 --> 00:57:56,560 until someone worked out a way to do it. 1090 00:57:56,560 --> 00:57:59,320 And that, my friends, that is cool. 1091 00:57:59,320 --> 00:58:01,680 ARCHIVE: And there you have the secret of the refrigerator. 1092 00:58:02,880 --> 00:58:05,600 Next time - it's the roller-coaster. 1093 00:58:05,600 --> 00:58:07,080 Oh, my God! 1094 00:58:07,080 --> 00:58:11,400 It's the story of some dodgy French physics in the 19th century... 1095 00:58:11,400 --> 00:58:14,680 Basically a torture device that you pay to go on. 1096 00:58:14,680 --> 00:58:16,760 ..NASA rocket scientists... 1097 00:58:16,760 --> 00:58:21,160 We can simulate the forces twirling the man round at a suitable rate. 1098 00:58:21,160 --> 00:58:25,080 ..and the vast vision of a cartoonist called Walt. 1099 00:58:25,080 --> 00:58:27,640 He says, "Bobby, build this." 1100 00:58:27,640 --> 00:58:28,880 Build a mountain. 1101 00:58:31,800 --> 00:58:34,920 The Open University has produced a free poster 1102 00:58:34,920 --> 00:58:39,000 exploring what lies behind the genius of some everyday objects. 1103 00:58:39,000 --> 00:58:40,800 To order a copy, call... 1104 00:58:44,120 --> 00:58:46,120 ..scan the QR code or go to... 1105 00:58:49,840 --> 00:58:52,160 ..and follow the links to the Open University.