0:00:08 > 0:00:11I'm standing on top of the modern world,
0:00:11 > 0:00:15on a structure built from some of the most extraordinary materials that humans have invented.
0:00:18 > 0:00:20Everything around me is man-made.
0:00:22 > 0:00:25And it's built of this.
0:00:25 > 0:00:27Sand and clay.
0:00:29 > 0:00:33We've transformed sand into transparent glass.
0:00:36 > 0:00:40Malleable clay has metamorphosised into hard earthenware
0:00:40 > 0:00:42and brittle porcelain.
0:00:42 > 0:00:46From rock and ash, we've unleashed the power of concrete,
0:00:46 > 0:00:50the most widely used man-made material in the world.
0:00:50 > 0:00:53I can see it's bending. It's bending quite a lot.
0:00:53 > 0:00:57These miracle materials are ceramics.
0:00:57 > 0:01:01All forged from the stuff of the Earth.
0:01:02 > 0:01:09And they have one thing in common - the transforming power of fire.
0:01:12 > 0:01:15I'm Mark Miodownik and, as a materials scientist,
0:01:15 > 0:01:19I have spent my life trying to unlock the secrets of matter.
0:01:21 > 0:01:24Yes! It doesn't break!
0:01:24 > 0:01:27This is the story of ceramics.
0:01:27 > 0:01:31Of clay, concrete and glass.
0:01:31 > 0:01:35The materials we've used to make our 21st-century world.
0:01:35 > 0:01:39How we've taken the very stuff of the Earth and transformed it
0:01:39 > 0:01:43into the buildings around us and the technology at our fingertips.
0:01:56 > 0:01:59This is one of the lightest solids on the planet.
0:02:00 > 0:02:04It's aerogel, it's 97% air, it's a glass
0:02:04 > 0:02:07and it's one of the most marvellous materials ever created.
0:02:09 > 0:02:14NASA use it to collect space dust, but let me show you something else it can do.
0:02:22 > 0:02:24It's a fantastic insulator.
0:02:24 > 0:02:27The temperature under here's about 1,300 degrees.
0:02:27 > 0:02:29Now watch this.
0:02:29 > 0:02:34I put a flower on it, no problem at all. Absolutely fine.
0:02:34 > 0:02:38I can even put my finger on it. It's barely warm.
0:02:38 > 0:02:39Absolutely fantastic.
0:02:39 > 0:02:43The secret of aerogel lies in its inner structure.
0:02:43 > 0:02:46It's actually full of billions of air holes.
0:02:46 > 0:02:49It's a glass foam, and that's why it's such a great insulator,
0:02:49 > 0:02:52and why it can absorb impacts.
0:02:52 > 0:02:53In the future, it might protect us
0:02:53 > 0:02:58against bomb blasts or insulate spacesuits on missions to Mars.
0:03:01 > 0:03:04Aerogel is almost 100% air.
0:03:04 > 0:03:08But it's the part that isn't that's important.
0:03:08 > 0:03:11An almost invisible sponge-like glass foam.
0:03:14 > 0:03:19Glass, mainly made from sand, is a special type of ceramic.
0:03:19 > 0:03:22But the story of how we learned to work ceramics
0:03:22 > 0:03:24begins with an earthenware pot.
0:03:26 > 0:03:29Clay was the first substance we learned to transform
0:03:29 > 0:03:33into a new material, about 29,000 years ago.
0:03:34 > 0:03:38And, for me, that's one of the most important moments in our history.
0:03:38 > 0:03:41It's the moment where we learnt to take the stuff of the Earth, clay,
0:03:41 > 0:03:44soft and malleable, and, using fire,
0:03:44 > 0:03:49transform it into something hard, immutable, a ceramic.
0:03:54 > 0:03:57The first pottery figurines were found
0:03:57 > 0:04:00in what is now the Czech Republic.
0:04:00 > 0:04:05Our ancestors dug clay out of the earth, they shaped it,
0:04:05 > 0:04:08and baked it in their fires.
0:04:08 > 0:04:13Much later, they made it into pots for storing grain and holding water.
0:04:14 > 0:04:19But they had little idea of the chemical processes they'd mastered.
0:04:22 > 0:04:26Magnified over 1,000 times, clay is made of thin,
0:04:26 > 0:04:30crystalline plates which are surrounded by water.
0:04:30 > 0:04:34This allows the plates to slip past one another,
0:04:34 > 0:04:36which is why the clay can be moulded.
0:04:38 > 0:04:40But fire changes it for ever.
0:04:44 > 0:04:48As clay is fired, the water evaporates.
0:04:50 > 0:04:53So the plates come closer together.
0:04:53 > 0:04:57In the intense heat, atomic bonds form between the plates
0:04:57 > 0:04:58and lock them into position.
0:05:01 > 0:05:04The clay has become hard and brittle.
0:05:04 > 0:05:08What later scientists would call a ceramic.
0:05:08 > 0:05:12Pottery became one of the foundations of civilisation.
0:05:14 > 0:05:17Although it had its weaknesses -
0:05:17 > 0:05:21it could be porous and would shatter easily -
0:05:21 > 0:05:23it would be thousands of years
0:05:23 > 0:05:26before we'd create anything significantly better.
0:05:28 > 0:05:30At least here in the West.
0:05:37 > 0:05:39It's 1701.
0:05:39 > 0:05:43A young alchemist, Johann Friedrich Bottger,
0:05:43 > 0:05:46is thrown into a castle dungeon by the King.
0:05:50 > 0:05:55Augustus The Strong imprisoned Bottger, not to improve pottery,
0:05:55 > 0:05:57but to make gold.
0:06:00 > 0:06:02This was an era in which alchemists believed
0:06:02 > 0:06:06they COULD turn base metals into gold, a tempting prospect
0:06:06 > 0:06:10for any king who wanted to fund their war or their court.
0:06:10 > 0:06:14Augustus ordered that Bottger be kept in prison
0:06:14 > 0:06:18until he revealed the secret of turning lead into gold.
0:06:24 > 0:06:27Picture the scene down in the dungeon.
0:06:27 > 0:06:30Bottger toiling in the unrelenting heat and foul air.
0:06:32 > 0:06:36Mixing, bubbling and heating endless cocktails of ingredients.
0:06:41 > 0:06:43At the end of it all, he produced no gold.
0:06:46 > 0:06:49Desperate to keep his head on his shoulders,
0:06:49 > 0:06:52Bottger had to find a way to appease the King.
0:06:52 > 0:06:56There was one thing that Augustus valued almost as much as gold.
0:06:56 > 0:07:00So Bottger set out on a quest to solve an age-old mystery,
0:07:00 > 0:07:04and, in doing so, he would change the Western world.
0:07:09 > 0:07:13Bottger had set his sights on the finest ceramic
0:07:13 > 0:07:15then known on earth - porcelain.
0:07:15 > 0:07:17The Chinese had held
0:07:17 > 0:07:20the secret of porcelain making for over 1,000 years.
0:07:21 > 0:07:28Finer, lighter, harder, whiter, with a glassy glaze.
0:07:28 > 0:07:33Porcelain was superior to any pottery we had created in the West.
0:07:33 > 0:07:38And it was highly prized. Known as white gold.
0:07:38 > 0:07:42The Chinese guarded their secret closely.
0:07:42 > 0:07:45It provided them with a huge trade monopoly.
0:07:45 > 0:07:49And despite centuries of experimentation and sending spies
0:07:49 > 0:07:54to China, nobody in the West could discover the secret of porcelain.
0:07:54 > 0:07:58And this was the task that Bottger set himself to save his skin.
0:08:01 > 0:08:04He needed to find out how the Chinese changed
0:08:04 > 0:08:07coarse earthenware into fine, strong porcelain.
0:08:11 > 0:08:16He started with the same basic ingredients
0:08:16 > 0:08:17that make earthenware pottery.
0:08:17 > 0:08:21So Bottger had to work out what other secret ingredients
0:08:21 > 0:08:23the Chinese were adding.
0:08:25 > 0:08:31Master potter Graham Taylor has been making porcelain for over 30 years.
0:08:31 > 0:08:34He knew what not to try. People tried to do it for centuries.
0:08:34 > 0:08:37They tried all sorts of things to add to clay.
0:08:37 > 0:08:42They tried adding talc, powdered glass, or shells, things like that,
0:08:42 > 0:08:44all trying to achieve that sort of white translucency,
0:08:44 > 0:08:47that vibrancy of porcelain.
0:08:47 > 0:08:49So what did Bottger try?
0:08:49 > 0:08:52Bottger had the advantage of having discovered a really,
0:08:52 > 0:08:56really fine type of china clay that came from Colditz.
0:08:56 > 0:09:01He then had to find various new things to add to that clay.
0:09:02 > 0:09:05There we go.
0:09:07 > 0:09:10So, here we've got china clay, pure, white clay.
0:09:10 > 0:09:14And in its powder form, it looks like flour.
0:09:14 > 0:09:18'Bottger experimented for years before finding
0:09:18 > 0:09:20'two critical ingredients to mix with his clay.'
0:09:20 > 0:09:25What he's adding to it as well are china stone.
0:09:25 > 0:09:28This is a decomposed volcanic mineral.
0:09:29 > 0:09:33And quartz, about 20% quartz, so here we've got, again,
0:09:33 > 0:09:37- another unassuming white powder. - Another white powder!
0:09:37 > 0:09:40And here, what we've got is the makings, seemingly, of porcelain.
0:09:40 > 0:09:42It doesn't look much, does it?
0:09:42 > 0:09:47Of course, what we need to add to make it into a clay is some water.
0:09:47 > 0:09:50So I'm just putting an amount of water in there.
0:09:50 > 0:09:52And we start to mix that up,
0:09:52 > 0:09:56and what you see happening here is we will get the paste.
0:09:57 > 0:10:00'But Bottger wasn't there yet.
0:10:00 > 0:10:05'If earthenware could be forged in a blazing fire, he realised
0:10:05 > 0:10:08'he'd have to improve his technology to make porcelain.'
0:10:08 > 0:10:11When they write about Bottger's kilns,
0:10:11 > 0:10:13they talk about narrow, horizontal kilns,
0:10:13 > 0:10:17so I think this is the sort of shape that they might have been.
0:10:17 > 0:10:20'By trial and error, Bottger discovered
0:10:20 > 0:10:23'he had to get his kiln to an extremely high temperature.
0:10:23 > 0:10:26'At least 1,300 degrees Celsius.'
0:10:26 > 0:10:29So, we get this burner going.
0:10:29 > 0:10:34'At this temperature, a different chemical process takes place'.
0:10:38 > 0:10:41The added secret ingredients, china stone and quartz,
0:10:41 > 0:10:44react to form a glassy glue.
0:10:45 > 0:10:49This flows into the gaps between the crystalline plates.
0:10:51 > 0:10:53The plates begin to dissolve.
0:10:53 > 0:10:58Needle-like crystals form, which help lock the plates into shape.
0:11:01 > 0:11:03As the porcelain cools, the glassy glue
0:11:03 > 0:11:08solidifies around these structures and locks them into place.
0:11:10 > 0:11:13This makes porcelain less porous than earthenware,
0:11:13 > 0:11:16so it's harder and much stronger.
0:11:19 > 0:11:23It had taken more than a decade, but Bottger was finally convinced
0:11:23 > 0:11:27he had something that might earn him his freedom.
0:11:27 > 0:11:32He decided it was time to prove his skills to the King.
0:11:33 > 0:11:37Legend has it that, when the King came to visit the workshop,
0:11:37 > 0:11:41Bottger decides to open the kiln, and pull out a teapot,
0:11:41 > 0:11:46apparently, from the kiln, while it's still glowing white hot,
0:11:46 > 0:11:50and plunge it into a bucket of water, to demonstrate
0:11:50 > 0:11:55the quality of the ware, and the sort of reported thing at the time
0:11:55 > 0:11:58was that he plunged it into water saying it must survive this test.
0:11:58 > 0:12:01Thermal shock, surely, would just shatter it.
0:12:01 > 0:12:04That's what I would expect, I really am very sceptical, and I think
0:12:04 > 0:12:07it's an elaboration of the story, and building up of the story,
0:12:07 > 0:12:10something which it maybe wasn't, but Bottger was quite a showman.
0:12:10 > 0:12:13- He really was a showman.- Have you ever tried a test like this?
0:12:13 > 0:12:15No, I haven't.
0:12:21 > 0:12:25- Nice and quiet.- Yes. That really makes a huge difference!
0:12:25 > 0:12:28- Got it?- Yes. Off we go. - Hold on, hold on.
0:12:30 > 0:12:34- OK.- That's it. Horizontally.
0:12:34 > 0:12:37- And onto there.- Oh, yes!- Beautiful.
0:12:37 > 0:12:44Now then, what we have here is one very hot porcelain bowl,
0:12:44 > 0:12:47- that has actually fused so much... - Did you want me to...?- Yes.
0:12:47 > 0:12:52- Tip that back. Into there. Lovely.- Yeah.- That's got it.
0:12:52 > 0:12:54And what we're going to do is...
0:12:56 > 0:13:02- Drop that into there. And it looks like Bottger might have been right. - My God! I'm really amazed at that!
0:13:05 > 0:13:09I can't believe it! It survived! That's amazing!
0:13:10 > 0:13:13That's like no ceramic that I have ever seen,
0:13:13 > 0:13:16- I really can't believe that. - That's me proved wrong.
0:13:16 > 0:13:19THEY LAUGH It survives perfectly well.
0:13:19 > 0:13:25'Bottger had finally solved the mystery of how to make porcelain.'
0:13:25 > 0:13:29And he did so while locked up in a dungeon and in fear of his life.
0:13:29 > 0:13:32Most people would go to pieces under that sort of pressure,
0:13:32 > 0:13:35but Bottger didn't. Instead, he pulled out of the bag
0:13:35 > 0:13:37one of the most wondrous pieces of material science.
0:13:39 > 0:13:44King Augustus eventually released Bottger in 1714,
0:13:44 > 0:13:4813 years after he was first imprisoned.
0:13:50 > 0:13:52Following Bottger's discovery,
0:13:52 > 0:13:55China finally lost its age-old monopoly on porcelain.
0:13:55 > 0:14:01And the balance of manufacturing wealth and power shifted to the West.
0:14:04 > 0:14:07But it took a lot less time for the West to unlock
0:14:07 > 0:14:09the secrets of another ceramic.
0:14:11 > 0:14:12Glass.
0:14:15 > 0:14:20It was the Romans who first mastered the skills to make blown glass.
0:14:20 > 0:14:25They heated sand with minerals and created a toffee-like substance
0:14:25 > 0:14:30that they could blow, stretch and mould into any shape they wanted.
0:14:32 > 0:14:37And, unlike any other solid they could make, it was transparent.
0:14:39 > 0:14:43Dr Caroline Jackson has studied the techniques of Roman glassmakers.
0:14:43 > 0:14:48- The Romans were the first to use glass for windows.- Really?- Yes.
0:14:48 > 0:14:52- What happened before then? - They just had either open windows
0:14:52 > 0:14:55or, in ceremonial places, they would use other materials,
0:14:55 > 0:14:58but that wouldn't let the light in quite so much.
0:14:58 > 0:15:01So people must have got pretty cold before the Romans?
0:15:01 > 0:15:04It certainly was. In Britain, it would have been quite draughty.
0:15:04 > 0:15:08What was the process like to make this glass?
0:15:08 > 0:15:10They essentially cast glass.
0:15:10 > 0:15:12They'd already got a casting process for vessels,
0:15:12 > 0:15:15so it's just an extension of that.
0:15:17 > 0:15:20Like pottery, glass can be made from very simple substances
0:15:20 > 0:15:24using only the power of fire.
0:15:25 > 0:15:28The sand, which is mainly quartz crystals,
0:15:28 > 0:15:31and the minerals or ash, are mixed and heated together.
0:15:33 > 0:15:37As the temperature rises to 600 degrees Celsius and beyond,
0:15:37 > 0:15:40they begin to melt.
0:15:45 > 0:15:50The mixture becomes a molten liquid and, like all liquids,
0:15:50 > 0:15:53its molecular structure is chaotic.
0:16:01 > 0:16:06As glass cools, its atoms bond with one another.
0:16:06 > 0:16:09But it can't form crystals as other ceramics would.
0:16:11 > 0:16:14That's because it cools too fast for its atoms
0:16:14 > 0:16:18to get into the regimented structure of a crystal.
0:16:18 > 0:16:22And this is one of the keys to its transparency.
0:16:25 > 0:16:28He's taking the hot glass out of the furnace now,
0:16:28 > 0:16:32and he's got a wet ladle, so it doesn't stick to that,
0:16:32 > 0:16:36then he pours it on to a very hot surface. Again, so it doesn't stick.
0:16:36 > 0:16:39And he's pressing the glass down while it's very hot and molten
0:16:39 > 0:16:42to try and get as thin a surface as he can possibly get.
0:16:42 > 0:16:44The glass is cooling all the time.
0:16:48 > 0:16:52He's pulling out now, with pincers, to try and get the square shape,
0:16:52 > 0:16:56and you see these actually on Roman glass examples.
0:16:56 > 0:16:58You see the pincer marks in the corners, sometimes.
0:17:00 > 0:17:02In making their windows,
0:17:02 > 0:17:07what excited the Romans was that they could see through them.
0:17:09 > 0:17:12The secret of what makes glass transparent is
0:17:12 > 0:17:14hidden deep within its atomic structure.
0:17:14 > 0:17:17Now everything, whether it's opaque or transparent,
0:17:17 > 0:17:22is made of atoms. Imagine this plate is an atom in an opaque material,
0:17:22 > 0:17:26and this tomato is its nucleus.
0:17:26 > 0:17:28Well, there's also electrons inside the atom,
0:17:28 > 0:17:31and they inhabit things called energy levels,
0:17:31 > 0:17:33and they look a bit like this.
0:17:33 > 0:17:36Now, when a photon of light hits the atom,
0:17:36 > 0:17:41well, it can promote one of the electrons to a higher energy level,
0:17:41 > 0:17:45so it absorbs that photon of light and so the material is opaque.
0:17:45 > 0:17:49So what happens when material is transparent?
0:17:49 > 0:17:52Well, you've still got the atom and you've still got the nucleus,
0:17:52 > 0:17:56and you've still got the electrons and their energy levels,
0:17:56 > 0:17:59but this time, the gap between the energy levels is bigger,
0:17:59 > 0:18:01so when the photon of light hits the atom,
0:18:01 > 0:18:05it doesn't have enough energy to promote one of the electrons
0:18:05 > 0:18:08to a higher energy state, and so, well, nothing can happen, the light
0:18:08 > 0:18:13has to travel straight through, and so the material is transparent.
0:18:16 > 0:18:20The Romans were justly proud of their glassmaking technology.
0:18:20 > 0:18:24They could make more advanced shapes than anybody else.
0:18:27 > 0:18:29But there was one other material they invented,
0:18:29 > 0:18:32which would have a much greater impact
0:18:32 > 0:18:35on both the ancient and modern worlds.
0:18:43 > 0:18:47Their inspiration may have come from volcanoes
0:18:47 > 0:18:49like Mount Vesuvius and Etna.
0:18:49 > 0:18:54When they erupt, they spew out ash and the Romans noticed that,
0:18:54 > 0:18:59when the ash got wet, it hardened and became almost as hard as stone.
0:18:59 > 0:19:04The Romans saw the potential to make a powerful new material.
0:19:07 > 0:19:11A material we now call concrete.
0:19:11 > 0:19:14Now I have to admit, although most people loathe concrete,
0:19:14 > 0:19:17I think it's one of those amazing materials we've ever created.
0:19:17 > 0:19:19I love the look of it, the feel of it,
0:19:19 > 0:19:22and the way that it's changed the way we live our lives.
0:19:28 > 0:19:34'Chris Brandon has studied Roman concrete for over 20 years.
0:19:34 > 0:19:36'And he's going to help me make some.
0:19:39 > 0:19:43'We're using volcanic ash called pozzolana ash
0:19:43 > 0:19:47'and adding burnt limestone made into a putty.
0:19:47 > 0:19:50'The same ingredients the Romans would have used.'
0:19:52 > 0:19:55How do we know that Romans made concrete this way?
0:19:55 > 0:19:57Is it written down somewhere, a recipe?
0:19:57 > 0:20:03Yes, there is a recipe in Vitruvius, Pliny also wrote about it.
0:20:05 > 0:20:10'We're not heating our mixture, but heat is still fundamental'.
0:20:12 > 0:20:16The pozzolana ash was formed as minerals reacted
0:20:16 > 0:20:19in the extreme heat of a volcano.
0:20:20 > 0:20:23And the Romans heated limestone themselves.
0:20:24 > 0:20:27As the heat drove off carbon dioxide,
0:20:27 > 0:20:32it turns limestone into the very reactive burnt limestone -
0:20:32 > 0:20:33quicklime.
0:20:36 > 0:20:40'We're adding water right now to make the cement paste.
0:20:40 > 0:20:43'That's the key ingredient of concrete.'
0:20:43 > 0:20:46We must make sure it is a stiff mix.
0:20:47 > 0:20:49You can see this is a paste now,
0:20:49 > 0:20:52something I can mould and shape into whatever I want.
0:20:54 > 0:20:58The water kicks off a complex set of chemical reactions.
0:21:00 > 0:21:02New compounds are formed.
0:21:02 > 0:21:07Some are gels which harden into these fibre-like fibrils,
0:21:07 > 0:21:11which can be seen magnified many thousand times.
0:21:13 > 0:21:17The fibrils grow into a hard, interlocking mesh
0:21:17 > 0:21:21that is the basis of concrete's strength.
0:21:21 > 0:21:25It's a reaction that can keep going for years,
0:21:25 > 0:21:29and the concrete goes on getting harder and harder.
0:21:35 > 0:21:39It was concrete that gave the Romans their great structures.
0:21:40 > 0:21:44Their amphitheatres, stadiums and the Dome of the Pantheon.
0:21:46 > 0:21:48Built almost 2,000 years ago,
0:21:48 > 0:21:54spanning a distance of more than 40 metres, the Pantheon still
0:21:54 > 0:21:57has the largest unreinforced concrete dome in the world.
0:22:01 > 0:22:05'Concrete was to create not just the foundations of Rome,
0:22:05 > 0:22:08'but of an entire empire.
0:22:08 > 0:22:11'The Romans needed to take command of the seas.'
0:22:11 > 0:22:15OK, well here's the mini harbour that we want to build.
0:22:15 > 0:22:19'And to do that, they had to build harbours'.
0:22:19 > 0:22:22- Is this going to go in just like this?- I hope so.- OK.
0:22:22 > 0:22:26- Drop it down.- Oh, hey! 'They discovered
0:22:26 > 0:22:30'a truly extraordinary property of their concrete -
0:22:30 > 0:22:33'it could set even under water'.
0:22:33 > 0:22:38- Won't that all just dissolve?- Let's wait for the water to clear.- OK.
0:22:38 > 0:22:42What we should see is a lump of concrete and water.
0:22:42 > 0:22:46I'm amazed. I thought it was going to sort of dissolve into this mud.
0:22:46 > 0:22:48And then that will be it. But there it is.
0:22:48 > 0:22:51And tomorrow, they'll be solid.
0:22:54 > 0:22:58The Romans were very lucky with their raw materials.
0:22:58 > 0:23:02The pozzolana ash from the nearby volcanoes
0:23:02 > 0:23:04had the perfect ingredients.
0:23:04 > 0:23:07When they were mixed together with water and burnt limestone,
0:23:07 > 0:23:11they produced compounds that weren't soluble,
0:23:11 > 0:23:14so, as soon as the chemical reactions started to form
0:23:14 > 0:23:19concrete's incredibly hard mesh, it wouldn't dissolve in water.
0:23:21 > 0:23:24- So, Chris, is this how the Romans built their harbours?- Yes.
0:23:24 > 0:23:27They could build out into the sea, where it would have been
0:23:27 > 0:23:32impossible to have constructed ports with any other material.
0:23:32 > 0:23:34It allowed the Romans to dominate the Mediterranean.
0:23:34 > 0:23:38- So this is the stuff of their empire?- Absolutely.
0:23:38 > 0:23:41This is the foundation of empire.
0:23:53 > 0:23:56You'd think, with the advances the Romans made in glass
0:23:56 > 0:24:00and concrete technology, that the scene was set for the modern era.
0:24:00 > 0:24:03But it didn't happen that way.
0:24:03 > 0:24:07With the decline of the Roman Empire, the production of glass
0:24:07 > 0:24:11fell away dramatically and concrete almost disappeared altogether.
0:24:11 > 0:24:13And it wouldn't be for another thousand years
0:24:13 > 0:24:16before those two materials were used together again.
0:24:22 > 0:24:25For glass, the next great breakthrough
0:24:25 > 0:24:28didn't come until the 15th century in Venice.
0:24:28 > 0:24:33And it was so significant that the Venetian glassmakers
0:24:33 > 0:24:37weren't allowed to leave the city or share the secrets of their art.
0:24:37 > 0:24:40To do so, was punishable by death.
0:24:42 > 0:24:46Their innovation was this - cristallo glass.
0:24:46 > 0:24:50The clearest glass the world had ever seen.
0:24:50 > 0:24:53It came from a combination of great expertise
0:24:53 > 0:24:56and the perfect raw materials.
0:24:58 > 0:25:01The Venetian glassmakers replaced ordinary sand
0:25:01 > 0:25:05with these clear quartz pebbles taken from the local river.
0:25:05 > 0:25:08They heated them up and submerged them in water to purify them
0:25:08 > 0:25:11and then ground them into a fine powder.
0:25:11 > 0:25:16The finest sand to create the finest, clearest glass.
0:25:18 > 0:25:24At first, this clear glass was just used to make decorative luxuries.
0:25:24 > 0:25:27But then, as in so many times in history,
0:25:27 > 0:25:30we took a material prized for its beauty
0:25:30 > 0:25:32and harnessed it to drive progress.
0:25:32 > 0:25:36Colourless glass was about to completely change the way we saw the world.
0:25:39 > 0:25:44Glass bends light, so if you can shape a piece of glass so that it
0:25:44 > 0:25:49all bends light to a focal point, well, that's what makes a lens.
0:25:53 > 0:25:57The light slows down as it travels from air into denser glass,
0:25:57 > 0:26:00and this makes light bend.
0:26:02 > 0:26:07As the light emerges, it speeds up and bends again.
0:26:07 > 0:26:13The amount it bends depends on the shape and thickness of the lens.
0:26:14 > 0:26:18Once you can bend light like this, you can magnify.
0:26:21 > 0:26:23The perfectly transparent cristallo glass
0:26:23 > 0:26:26led the way to an extraordinary innovation.
0:26:28 > 0:26:29The telescope.
0:26:33 > 0:26:37It was the 17th century and the planets had only ever been seen
0:26:37 > 0:26:40as pinpricks of light in the night sky.
0:26:40 > 0:26:43But using a telescope he built himself, the renowned physicist,
0:26:43 > 0:26:47Galileo, revealed the wonders of these distant worlds.
0:26:52 > 0:26:57In Galileo's day, one way to grind class into a lens was to blow it
0:26:57 > 0:27:00and open it out into a sheet.
0:27:01 > 0:27:06When this cooled, you had to cut a small piece
0:27:06 > 0:27:09and then hold it against a spinning cannonball to curve it.
0:27:12 > 0:27:14Galileo kept improving his lenses
0:27:14 > 0:27:17until he managed to make a magnification of 20 times.
0:27:20 > 0:27:24He saw and sketched the mountains and craters on our moon.
0:27:24 > 0:27:28And he discovered moons orbiting Jupiter, revealing that
0:27:28 > 0:27:32not every thing in the heavens revolved around the Earth.
0:27:34 > 0:27:37Our belief in a universe with Earth at its centre
0:27:37 > 0:27:39had come crashing down.
0:27:39 > 0:27:44Our worldview had been transformed by the glass lens.
0:27:44 > 0:27:47A simple disc of heated sand.
0:27:50 > 0:27:54But what's even more exciting to me is what happened when
0:27:54 > 0:28:00we turned the telescope around and started looking down instead of up.
0:28:00 > 0:28:04The irascible but brilliant English scientist, Robert Hooke, wanted to
0:28:04 > 0:28:09use the magnifying power of lenses to see what was under his very nose.
0:28:09 > 0:28:12He spent much of his life looking down the microscope.
0:28:16 > 0:28:19He described a whole new microscopic world
0:28:19 > 0:28:23and produced a book of astoundingly intricate drawings.
0:28:25 > 0:28:26Using glass lenses,
0:28:26 > 0:28:30Hooke had begun to unlock the secrets of life itself.
0:28:30 > 0:28:34He had discovered the complexity of inner space.
0:28:35 > 0:28:37At last, we would be able to penetrate
0:28:37 > 0:28:40further into the hidden world of materials.
0:28:43 > 0:28:46We had come a long way with the sand,
0:28:46 > 0:28:50clay and rock beneath our feet.
0:28:50 > 0:28:54But we were relying on materials which still had weaknesses.
0:28:54 > 0:28:56TRAIN WHISTLE BLOWS
0:28:56 > 0:28:58To build the modern world,
0:28:58 > 0:29:01we'd have to learn to work around their limitations.
0:29:04 > 0:29:09For the Victorian engineers, one challenge was concrete.
0:29:09 > 0:29:13It had so many advantages. But one fatal flaw.
0:29:17 > 0:29:22Dr Phil Purnell has been studying concrete for over 15 years.
0:29:22 > 0:29:24Well, today, Mark,
0:29:24 > 0:29:27we're going to get you to walk a concrete plank to give us
0:29:27 > 0:29:29some indication of how concrete could let us down if not careful.
0:29:29 > 0:29:33- Wow, it really is a concrete plank. - It certainly is, yes.
0:29:33 > 0:29:36- We're going to get you to walk across it.- OK.
0:29:36 > 0:29:38So if you would like to sort of get onto that there.
0:29:38 > 0:29:41I'm slightly nervous about this, because I can't
0:29:41 > 0:29:44imagine that there is a good reason for me walking a plank.
0:29:44 > 0:29:47As you gently inch your weight across the plank,
0:29:47 > 0:29:49you're making it bend, you're bending the concrete.
0:29:49 > 0:29:53And when you bend something, the top of that goes into crushing,
0:29:53 > 0:29:55it's being crushed, it goes into compression.
0:29:55 > 0:30:00The bottom of it is pulled apart and goes into what we call tension.
0:30:00 > 0:30:04'As the plank curves a tiny bit under my weight,
0:30:04 > 0:30:08'the top surface becomes concave and is squashed,
0:30:08 > 0:30:10'while the bottom is stretched.'
0:30:12 > 0:30:14Of course, as I get closer to the middle,
0:30:14 > 0:30:16I'm making the plank work much harder.
0:30:16 > 0:30:18When you're in the middle, you have
0:30:18 > 0:30:21a maximum crushing on the top and a maximum pulling underneath.
0:30:21 > 0:30:23- Concrete is very, very good... - CRASH!
0:30:23 > 0:30:26..but as you can see, very, very poor in tension.
0:30:26 > 0:30:30- So what we've demonstrated... - That's exactly what you don't want a building to do!- Exactly.
0:30:30 > 0:30:33- You really don't want that to happen.- OK, wow.
0:30:33 > 0:30:37This is actually a thick piece of concrete, I'm really surprised.
0:30:37 > 0:30:41That's as thick as your concrete floors at home or an office block.
0:30:41 > 0:30:43- The genuine thickness of concrete.- Wow.
0:30:44 > 0:30:49'The reason concrete can snap like this is down to its inner structure.'
0:30:52 > 0:30:57Concrete isn't entirely solid. It's riddled with tiny holes.
0:30:58 > 0:31:01When it's compressed, the holes close up
0:31:01 > 0:31:03and the concrete stays strong.
0:31:05 > 0:31:09But when it's under tension, the holes open up.
0:31:09 > 0:31:13Stress will concentrate at the edges of the holes.
0:31:13 > 0:31:15Here, cracks can start...
0:31:17 > 0:31:22..and the stress can be powerful enough to split the concrete.
0:31:24 > 0:31:28As the cracks grow, they join up with other cracks
0:31:28 > 0:31:31and can rip the concrete path.
0:31:37 > 0:31:40So, to build bigger, we would need to find a way
0:31:40 > 0:31:46of working around concrete's one great weakness.
0:31:47 > 0:31:51So, what is this trick? What's the answer to making concrete stronger,
0:31:51 > 0:31:54resisting these bending forces?
0:31:54 > 0:31:59Well, back in the 1850s, there was a plasterer from Newcastle,
0:31:59 > 0:32:03called Mr Wilkinson, and he was making concrete floor slabs.
0:32:03 > 0:32:06And what he noticed is that these slabs have the tendency
0:32:06 > 0:32:08to crack in between the joists.
0:32:08 > 0:32:11Just like my unfortunate experience with the plank.
0:32:11 > 0:32:15Exactly like your unfortunate experience with the plank, yes.
0:32:15 > 0:32:18So Wilkinson noticed where the cracks are appearing
0:32:18 > 0:32:21in his concrete floor slabs and he had an idea, and a very bright idea.
0:32:21 > 0:32:25And he took some barrel hoops,
0:32:25 > 0:32:29took some of the flat hoops that go around and hold a barrel together,
0:32:29 > 0:32:32and he placed them in the concrete where he noticed the cracks
0:32:32 > 0:32:36were appearing, where he knew we had to resist these pulling forces.
0:32:37 > 0:32:42- So he invented reinforced concrete? - He did. Back in 1853. Yes.
0:32:42 > 0:32:46- What a dude.- Absolutely! He laid the foundations for modern urban life.
0:32:46 > 0:32:51Without reinforced concrete, nothing we see around us would exist.
0:32:53 > 0:32:55Reinforced concrete might seem simple,
0:32:55 > 0:32:59but it works because steel is the perfect partner for concrete.
0:33:00 > 0:33:02They both share a surprising quality.
0:33:04 > 0:33:10They expand and contract at the same rate when they get hot or cold.
0:33:10 > 0:33:15And unlike concrete, steel is strong when it's under tension.
0:33:15 > 0:33:19It bends without breaking, like concrete does.
0:33:26 > 0:33:28As we learned more about materials,
0:33:28 > 0:33:33we found it easier to find clever ways to fix problems.
0:33:33 > 0:33:39For instance, we didn't try to stop concrete cracking completely,
0:33:39 > 0:33:42just to control it.
0:33:42 > 0:33:45So, to test this beam, we're pushing down on it repeatedly
0:33:45 > 0:33:49with a force of about 2.5 tons, so we are putting it under the sort
0:33:49 > 0:33:53of loads that we might expect, for example, a rail or road bridge
0:33:53 > 0:33:56to be put under when large vehicles go over the top of it.
0:33:56 > 0:33:58I can see it's bending. It's bending quite a lot.
0:33:58 > 0:34:00It's bending quite a lot, yes.
0:34:00 > 0:34:02I hate to tell you this, but it's cracking.
0:34:02 > 0:34:03It's cracking quite considerably.
0:34:03 > 0:34:06But look at the difference compared to our plank in the other room.
0:34:06 > 0:34:09Here, our cracks are only travelling a certain way up,
0:34:09 > 0:34:14because what is happening is, the steel is holding the beam together,
0:34:14 > 0:34:16the steel is holding that crack together.
0:34:16 > 0:34:20If I just traced this crack out, to highlight it a bit more clearly.
0:34:20 > 0:34:24We can see the crack is travelling up from the bottom of the beam.
0:34:24 > 0:34:27But it stops roughly halfway up the beam,
0:34:27 > 0:34:31so I will just raw a dotted line there to show where it stopped.
0:34:31 > 0:34:33And everything above that dotted line is
0:34:33 > 0:34:37going into the crushing force, into compression.
0:34:37 > 0:34:41Everything below that dotted line is being pulled, going into tension.
0:34:41 > 0:34:43So above the line, the concrete is doing the work.
0:34:43 > 0:34:46Below the line, the steel is doing the work.
0:34:46 > 0:34:48So we're getting the very best out of both materials.
0:34:48 > 0:34:52- So that crack is stable? Nothing to worry about?- It's perfectly stable.
0:34:52 > 0:34:55All reinforced concrete buildings are cracked to some degree,
0:34:55 > 0:34:58and the important thing, when designing reinforced concrete,
0:34:58 > 0:35:01is to make sure that you have lots and lots
0:35:01 > 0:35:04and lots of small cracks instead of one very, very big crack.
0:35:09 > 0:35:12Most people see concrete as drab, grey and ugly.
0:35:12 > 0:35:14It hasn't got many fans.
0:35:14 > 0:35:16But I think it's an extraordinary material.
0:35:16 > 0:35:18You can build man-made mountains with it.
0:35:18 > 0:35:20Buildings of any shape you want.
0:35:20 > 0:35:23Structures that will last for thousands of years.
0:35:23 > 0:35:26And that's the secret of concrete's success.
0:35:27 > 0:35:31Many of the iconic structures of our era, the Sydney Opera House,
0:35:31 > 0:35:36the Millau Viaduct, the tallest bridge in the world,
0:35:36 > 0:35:41and Dubai's Burj Khalifa, the world's tallest building,
0:35:41 > 0:35:44wouldn't exist without reinforced concrete.
0:35:50 > 0:35:54Reinforced concrete is flexible and versatile and it's freed us
0:35:54 > 0:35:57from the limitations of stone and brick.
0:35:57 > 0:36:01In the age of concrete, the only limitation is our imagination.
0:36:01 > 0:36:07The Industrial Revolution didn't just give us reinforced concrete,
0:36:07 > 0:36:12manufacturers finally managed to produce clear glass on a mass scale.
0:36:14 > 0:36:18So while concrete was giving us bigger buildings,
0:36:18 > 0:36:22glass was giving us this - lager.
0:36:27 > 0:36:31People started to drink beer out of clear glasses
0:36:31 > 0:36:33rather than opaque mugs.
0:36:33 > 0:36:37And they didn't like the dark, murky liquid they saw.
0:36:41 > 0:36:47So a Czech brewery hired one Josef Groll, who created the clear,
0:36:47 > 0:36:51golden brew, far more appealing to the 19th-century eye.
0:36:55 > 0:37:00Lager was born and became the world's most popular tipple.
0:37:04 > 0:37:08But while we could mass-produce small bits of glass like this,
0:37:08 > 0:37:11we still hadn't found the way to make glass at a scale
0:37:11 > 0:37:13big enough to build our modern cities.
0:37:16 > 0:37:20It wasn't that we hadn't tried to make large sheets of glass,
0:37:20 > 0:37:23but they'd always had inherent weaknesses.
0:37:24 > 0:37:28If you make glass the traditional way, it may look perfect,
0:37:28 > 0:37:31but it will always have a few flaws in it.
0:37:31 > 0:37:34And you probably can't even see them with the naked eye,
0:37:34 > 0:37:37but with a microscope like this, you can.
0:37:37 > 0:37:40So I'm just going to explore the inner world of glass here.
0:37:40 > 0:37:44And have a look for some...
0:37:44 > 0:37:46Yes, there's one, a little bubble.
0:37:46 > 0:37:51And there's another one, a little tiny little air bubble, actually.
0:37:51 > 0:37:59And if I refocus, to look at the surface, then, I can see scratches.
0:37:59 > 0:38:01Quite a lot of them.
0:38:01 > 0:38:05'And any imperfections in glass could have a dramatic effect.'
0:38:05 > 0:38:08So this is a modern pane of glass.
0:38:08 > 0:38:12And it has very few flaws in it. And so it's pretty strong.
0:38:14 > 0:38:16It's pretty impressive.
0:38:16 > 0:38:21Now, what if I was to put artificially some flaws in there?
0:38:21 > 0:38:24How would that affect the strength?
0:38:24 > 0:38:26Got just the tool for the job here.
0:38:36 > 0:38:42Let's put this back up again, and right, now,
0:38:42 > 0:38:46I've introduced a flaw into this piece of glass, a scratch,
0:38:46 > 0:38:50very thin scratch, let's see if it affects the strength.
0:38:53 > 0:38:57Mmm. Just as I suspected.
0:39:01 > 0:39:05It might seem strange that a single scratch could weaken
0:39:05 > 0:39:09an entire pane of glass so catastrophically.
0:39:09 > 0:39:13But it all comes down to the nature of ceramic materials.
0:39:16 > 0:39:18Any defect courses a point in the glass
0:39:18 > 0:39:21where the stress will concentrate.
0:39:21 > 0:39:25Even a small force can rip the atoms apart
0:39:25 > 0:39:28at the point it's most concentrated.
0:39:30 > 0:39:32As the atomic bonds break,
0:39:32 > 0:39:38the stress is focused on to the next atom, and the next, and the next.
0:39:38 > 0:39:43If the crack reaches a critical length, it's unstoppable.
0:39:43 > 0:39:46The whole pane of glass will break.
0:39:50 > 0:39:53Perfection is a very appealing concept,
0:39:53 > 0:39:56but with glass, it's really a necessity.
0:39:56 > 0:39:57The bigger the piece of glass,
0:39:57 > 0:40:00the more likely it is to have a fatal flaw.
0:40:00 > 0:40:04And if we were going to build big with glass,
0:40:04 > 0:40:08you need to find a way of making it more perfect.
0:40:10 > 0:40:15The breakthrough came in 1952, over a sink full of washing-up.
0:40:17 > 0:40:20Glass technician Alistair Pilkington was trying to achieve
0:40:20 > 0:40:26the glassmakers Holy Grail - a sheet of perfect, flawless glass.
0:40:28 > 0:40:32The story goes that he was washing up the dishes and he noticed
0:40:32 > 0:40:36a film of washing-up liquid floated on the surface of the water.
0:40:36 > 0:40:37He had a brainwave.
0:40:41 > 0:40:45Pilkington's idea was to create sheet glass
0:40:45 > 0:40:47by floating it on a bed of molten metal.
0:40:53 > 0:40:56It was an ambitious idea, but brilliant.
0:40:56 > 0:41:00And heat was once again the transforming power.
0:41:02 > 0:41:06Heating the metal until it was molten would keep the glass
0:41:06 > 0:41:09hot enough to remain liquid and, like the washing-up liquid
0:41:09 > 0:41:14on the water, Pilkington knew that glass and metal wouldn't mix.
0:41:16 > 0:41:20The glass would simply float on top of the molten metal,
0:41:20 > 0:41:22spreading out in a puddle.
0:41:22 > 0:41:26And it would settle into exactly the same thickness all over,
0:41:26 > 0:41:28because of gravity.
0:41:28 > 0:41:30When it cooled,
0:41:30 > 0:41:34this glass should be as close to perfection as we could achieve.
0:41:37 > 0:41:43It took seven years and more than £7 million to develop float glass.
0:41:44 > 0:41:46But the process was perfected.
0:41:46 > 0:41:50And it's still the way we make large sheets of glass today.
0:41:58 > 0:42:01But even flawless glass was still brittle
0:42:01 > 0:42:03and dangerous if it shattered.
0:42:05 > 0:42:09To use glass for our buildings in huge, weight-bearing sheets,
0:42:09 > 0:42:12we needed a glass that was stronger and safer.
0:42:12 > 0:42:16A glass a bit more like this.
0:42:19 > 0:42:21All right, come on then.
0:42:28 > 0:42:30Let's do it properly!
0:42:37 > 0:42:41'It takes a 50 kilogram weight propelled at speed
0:42:41 > 0:42:44'to break this glass.
0:42:44 > 0:42:46'It's up to five times stronger than ordinary glass.
0:42:48 > 0:42:51'The secret, again, lies in the material itself
0:42:51 > 0:42:56'and the transforming power of heat in a process called tempering.'
0:42:59 > 0:43:04The glass is heated and expands. But then it's cooled so rapidly,
0:43:04 > 0:43:08that the outside surfaces contract faster than the inside.
0:43:11 > 0:43:13This sets up forces within the glass.
0:43:15 > 0:43:20The middle ends up under tension, being pulled by the outside,
0:43:20 > 0:43:25which in turn is under compression, squeezed.
0:43:27 > 0:43:31'This compression force holds it together strongly,
0:43:31 > 0:43:33'so it won't break as easily.
0:43:33 > 0:43:37'But like an explosive charge waiting to go off,
0:43:37 > 0:43:40'once the internal stresses are released,
0:43:40 > 0:43:43'the whole pain disintegrates almost instantaneously.
0:43:44 > 0:43:47'And it forms, not a few large cracks,
0:43:47 > 0:43:49'but millions of smaller ones.'
0:43:51 > 0:43:54Instead of breaking into spiky shards
0:43:54 > 0:43:56that can cut or even kill you,
0:43:56 > 0:43:59this type of glass crumbles into blunt pieces
0:43:59 > 0:44:01that won't do you much harm at all.
0:44:02 > 0:44:05'But it's still breaks.
0:44:05 > 0:44:09'The search was on for a way of making even tougher glass.
0:44:09 > 0:44:14'And once again, we turned to a combination of two materials
0:44:14 > 0:44:16'with complementary properties.'
0:44:17 > 0:44:21This piece of advanced safety glass is actually two layers
0:44:21 > 0:44:26of tempered glass, a kind of glass sandwich with a plastic filling.
0:44:28 > 0:44:30'Plastic is flexible,
0:44:30 > 0:44:34'so it helps the glass absorb energy from impacts without breaking.'
0:44:36 > 0:44:38It was so tough,
0:44:38 > 0:44:41we can be more ambitious with glass than ever before.
0:44:41 > 0:44:43In theory, I should be able to jump on this.
0:44:45 > 0:44:47Yes! It doesn't break!
0:44:50 > 0:44:53You don't have to use it for windows, you can use it
0:44:53 > 0:44:57for floors, for walls, staircases, it will even withstand hurricanes.
0:44:57 > 0:45:03Incredible stuff. We can even make it bullet-proof and bomb-proof.
0:45:08 > 0:45:10Unbelievable.
0:45:11 > 0:45:15Toughened, laminated glass and reinforced concrete
0:45:15 > 0:45:20finally brought us into the age of the skyscraper and beyond.
0:45:28 > 0:45:32Ceramics are now shaping society in ways that are more profound
0:45:32 > 0:45:33than the buildings we live in.
0:45:36 > 0:45:40We've discovered that, at the very small-scale,
0:45:40 > 0:45:42and at extreme temperatures,
0:45:42 > 0:45:46these materials behave in ways that we just hadn't imagined.
0:45:47 > 0:45:52And that's propelled us into the information age.
0:45:55 > 0:45:58'It's a story that didn't begin in a high-tech lab,
0:45:58 > 0:46:03'but in the dentist's chair.' At the beginning of the 20th century,
0:46:03 > 0:46:07inventors realised that bent quartz rods could carry light.
0:46:07 > 0:46:11And so they created the dental illuminator.
0:46:11 > 0:46:16'Then, a German medical student took the idea further.
0:46:16 > 0:46:19'He assembles lots of thin fibres into bundles
0:46:19 > 0:46:24'to see if he could transmit not just light, but an image.'
0:46:24 > 0:46:28His goal was to look at the inaccessible parts of the body during surgery.
0:46:28 > 0:46:31'And fibre-optic bundles were perfect.
0:46:31 > 0:46:34'They could follow the contours of the body,
0:46:34 > 0:46:36'because of a surprising property of glass.'
0:46:38 > 0:46:42Glass of the everyday scale is brittle and stiff,
0:46:42 > 0:46:46but at the microscale, it behaves totally differently.
0:46:46 > 0:46:48It bends.
0:46:50 > 0:46:53You can only see this amazing elastic property of glass
0:46:53 > 0:46:57in something as thin as an optical fibre,
0:46:57 > 0:46:59the diameter of human hair.
0:47:02 > 0:47:05Atoms in glass are connected by bonds,
0:47:05 > 0:47:08which behave a little like stiff springs.
0:47:09 > 0:47:12This means glass can bend a tiny bit.
0:47:14 > 0:47:19The finer the glass thread, the less force it needs to bend.
0:47:19 > 0:47:22So the less likely it is to crack.
0:47:24 > 0:47:27And in such a fine thread, drawn from molten glass,
0:47:27 > 0:47:31there's less chance of a defect, which could make it shatter.
0:47:35 > 0:47:38That's not the only thing that's special about this glass.
0:47:38 > 0:47:43It's also incredibly pure, so light can travel down it for miles.
0:47:45 > 0:47:48But light normally travels in straight lines,
0:47:48 > 0:47:50so how does it go around these bends?
0:47:52 > 0:47:56'To find out, I'm with Dr Natalie Wheeler,
0:47:56 > 0:47:59'who researches optical fibres at the University of Southampton.'
0:47:59 > 0:48:03So here we have a length of optical fibre, and as you can see,
0:48:03 > 0:48:06it's extremely thin, and also, seeing as it's been coated with
0:48:06 > 0:48:10a polymer during the fabrication process, it's also extremely strong.
0:48:10 > 0:48:15Inside the coating of this optical fibre is a glass core,
0:48:15 > 0:48:18surrounded by a glass cladding layer.
0:48:18 > 0:48:22It's these two layers that help the light go around bends.
0:48:22 > 0:48:26We can actually demonstrate how this works using this set up here.
0:48:26 > 0:48:30- If you would like to just pull out that cork there.- This one?- Yeah.
0:48:31 > 0:48:36Wow! That's amazing! Look at that!
0:48:37 > 0:48:41'This laser light mimics what happens in an optical fibre.''
0:48:43 > 0:48:46'When light travels from a dense to a less dense medium,
0:48:46 > 0:48:48'like this liquid to air,
0:48:48 > 0:48:51'or from the glass core to its cladding layer,
0:48:51 > 0:48:57'what happens to the light depends on the angle at which it hits the boundary.
0:48:57 > 0:49:00'If the angle is large enough, it won't pass through/
0:49:00 > 0:49:02'It'll be reflected back in.'
0:49:03 > 0:49:06At the interface between the two materials,
0:49:06 > 0:49:10the light is being reflected, and you can see it bouncing along here.
0:49:10 > 0:49:14So the interface between them allows the total internal reflection?
0:49:14 > 0:49:17- Exactly.- That's absolutely fantastic.
0:49:17 > 0:49:22Using these amazing properties of optical fibres, in 1930,
0:49:22 > 0:49:26medical student, Heinrich Lamm, successfully transmitted
0:49:26 > 0:49:30the first image of a lightbulb filament using an optical fibre bundle.
0:49:32 > 0:49:37Then scientists realised they could have a far more powerful use -
0:49:37 > 0:49:42to transmit vast amounts of information at the speed of light.
0:49:47 > 0:49:50Optical fibres have become a foundation
0:49:50 > 0:49:53of the information revolution.
0:49:55 > 0:49:58Without them, we wouldn't have our world of instant phone calls,
0:49:58 > 0:50:01e-mails, cable TV or the Internet.
0:50:03 > 0:50:07Today, a single strand of optical fibre can transmit
0:50:07 > 0:50:122.5 million times more information than a standard copper cable.
0:50:12 > 0:50:15In fact, over the last 50 years,
0:50:15 > 0:50:18ceramics have been taking over from metals
0:50:18 > 0:50:22in a materials revolution that gave us our high-tech, high speed world.
0:50:22 > 0:50:26Ceramics have also been replacing metals
0:50:26 > 0:50:28in medicine and in electronics.
0:50:30 > 0:50:34But there's one essential of life that surely metals are vital for -
0:50:34 > 0:50:35electricity.
0:50:38 > 0:50:44Electricity travels down miles and miles of metal wires to reach us.
0:50:44 > 0:50:46And because of the way metals conduct,
0:50:46 > 0:50:49some of the energy is lost along the way.
0:50:50 > 0:50:55If I make a small electric circuit with some copper wire,
0:50:55 > 0:50:58a battery and a bulb, the bulb burns
0:50:58 > 0:51:02pretty brightly, but now, if I just use a longer wire,
0:51:02 > 0:51:0665 metres of it, same bulb, same battery,
0:51:06 > 0:51:08it's much duller.
0:51:08 > 0:51:12So the wire absorbs quite a lot of the electricity.
0:51:12 > 0:51:15So when it comes to crossing countries and continents,
0:51:15 > 0:51:18we lose a massive amount of energy.
0:51:18 > 0:51:21The UK's electricity network loses more than 7% of the electricity
0:51:21 > 0:51:24just getting from the power station to your plug.
0:51:27 > 0:51:30But that could change and it's all down to the way
0:51:30 > 0:51:34some materials respond to extreme temperatures.
0:51:36 > 0:51:40This time, the transformation isn't due to the power of heat,
0:51:40 > 0:51:42but of cold.
0:51:46 > 0:51:50In 1911, Dutch physicist Heike Kamerlingh Onnes
0:51:50 > 0:51:54was testing materials at extremely low temperatures.
0:51:55 > 0:52:00He cooled mercury down to the temperature of liquid helium.
0:52:00 > 0:52:03Minus 269 degrees Celsius.
0:52:03 > 0:52:07That's just four degrees above absolute zero.
0:52:09 > 0:52:13Onnes discovered something that nobody had ever seen before.
0:52:13 > 0:52:15At these extreme temperatures,
0:52:15 > 0:52:19mercury conducts electricity without losing any energy at all.
0:52:19 > 0:52:22He called it superconductivity.
0:52:27 > 0:52:32In a metal, electricity is conducted when electrons travel through it.
0:52:32 > 0:52:34At normal temperatures,
0:52:34 > 0:52:38the electrons bump into atoms and lose energy.
0:52:38 > 0:52:41It's called electrical resistance.
0:52:42 > 0:52:47But at extremely low temperatures, the electrons can pair up and
0:52:47 > 0:52:52navigate through the atoms without bumping into them and losing energy.
0:52:52 > 0:52:55The metal now has no electrical resistance.
0:52:59 > 0:53:03Onnes received a Nobel Prize for his work.
0:53:03 > 0:53:06And in the years that followed, scientists discovered
0:53:06 > 0:53:12that many other metals become superconductors at temperatures close to absolute zero.
0:53:14 > 0:53:17With society depending more and more on electricity,
0:53:17 > 0:53:20superconductors seem to have a huge potential.
0:53:20 > 0:53:24But the breakthrough was as frustrating as it was exciting.
0:53:24 > 0:53:28How could we find a use for something that only worked at such extreme temperatures?
0:53:29 > 0:53:34What was needed was a material that would perform like the superconducting metals,
0:53:34 > 0:53:39but at a temperature that wasn't down near absolute zero.
0:53:42 > 0:53:45And when the breakthrough came, it wasn't the material
0:53:45 > 0:53:48that anyone expected to conduct electricity at all.
0:53:48 > 0:53:51It wasn't a metal. It was a ceramic.
0:53:51 > 0:53:54This is a ceramic called yttrium barium copper oxide,
0:53:54 > 0:53:58and not only does it not conduct electricity, it doesn't
0:53:58 > 0:54:02really behave very interestingly at all to electricity or magnets.
0:54:04 > 0:54:08It seems dead. But cold does many strange things to this material.
0:54:08 > 0:54:11If we cool it down
0:54:11 > 0:54:14and, admittedly, we have to cool it down quite a lot,
0:54:14 > 0:54:18to liquid nitrogen temperatures, that's minus 196 degrees centigrade.
0:54:23 > 0:54:28It takes a few minutes for the liquid nitrogen to cool it right down,
0:54:28 > 0:54:32and when it does, the ceramic becomes a superconductor.
0:54:32 > 0:54:35And it has another trick up its sleeve.
0:54:37 > 0:54:39Now when I place a magnet over the ceramic,
0:54:39 > 0:54:41something completely different happens.
0:54:44 > 0:54:46It seems like the magnet floats on air.
0:54:46 > 0:54:49What's happening is it is being levitated by the ceramic.
0:54:49 > 0:54:52The ceramic is repelling the magnetic field of the magnet.
0:54:52 > 0:54:54It's absolutely extraordinary.
0:54:58 > 0:55:02The cold has changed the way the ceramic behaves.
0:55:02 > 0:55:05It's showing another material miracle
0:55:05 > 0:55:07that's unique to superconductors.
0:55:09 > 0:55:13Normally, this ceramic isn't affected at all by a magnet.
0:55:14 > 0:55:19But when the ceramic is cooled, and becomes a superconductor,
0:55:19 > 0:55:24an external magnetic field makes electrical currents flow within it.
0:55:24 > 0:55:28These generate their own magnetic field
0:55:28 > 0:55:30which repels the external one.
0:55:33 > 0:55:37And so a ceramic can repel a magnet.
0:55:37 > 0:55:41This ceramic has now become a superconductor and that means
0:55:41 > 0:55:45it can conduct electricity without losing any energy.
0:55:45 > 0:55:49It can do that when it's cooled to about minus 196 degrees centigrade.
0:55:49 > 0:55:52That may sound extreme, but it's pretty warm compared
0:55:52 > 0:55:56to the temperatures you need to make metals superconduct.
0:55:56 > 0:55:58Since they discovered this,
0:55:58 > 0:56:03scientists have begun to design ceramics at the atomic level.
0:56:03 > 0:56:06They've added different elements, atom by atom,
0:56:06 > 0:56:08in search of their ultimate aim.
0:56:09 > 0:56:14Superconductors that will work at practical temperatures.
0:56:17 > 0:56:19Degree by degree, we're approaching our goal.
0:56:19 > 0:56:23We currently use this thick copper cable to transmit electricity.
0:56:23 > 0:56:28But it can now be replaced by this thin superconducting ceramic cable.
0:56:28 > 0:56:32And as long as it's cooled, it will lose no electricity.
0:56:34 > 0:56:36In America, ceramic superconductors
0:56:36 > 0:56:39have started to be used in the power grid.
0:56:41 > 0:56:45China and Korea are planning to use them in cities of the future.
0:56:49 > 0:56:53In years to come, they could transport electricity on a massive scale.
0:56:56 > 0:56:59Just imagine, solar farms in the desert could be supplying
0:56:59 > 0:57:04our homes in Britain with minimal energy being lost on the way.
0:57:11 > 0:57:13Ceramics have defined our modern world.
0:57:13 > 0:57:16From the unlikely beginnings of sand and clay,
0:57:16 > 0:57:22we've created the stuff to build amazing cities full of light.
0:57:22 > 0:57:25And created the electronic materials that have sparked
0:57:25 > 0:57:27an information revolution.
0:57:27 > 0:57:30Metals have moved us out of the Stone Age
0:57:30 > 0:57:33and helped us conquer land, sea and air.
0:57:36 > 0:57:40Plastics brought us the era of man-made materials
0:57:40 > 0:57:44and transformed our lives.
0:57:44 > 0:57:47Over the last century,
0:57:47 > 0:57:52we've designed more new materials than at any stage in human history.
0:57:55 > 0:57:58And, as for the future, well, I believe we've only scratched
0:57:58 > 0:58:01the surface of what these marvellous materials can do.
0:58:19 > 0:58:24Subtitles by Red Bee Media Ltd