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00:08On the 14th of August 1894, an excited crowd gathered outside Oxford's Natural History Museum.
00:18This huge Gothic building was hosting the annual meeting of the British Association for the
00:24Advancement of Science. Over 2,000 tickets had been sold in advance and the museum was
00:32already packed, waiting for the next talk to be given by Professor Oliver Lodge.
00:40His name might not be familiar to us now, but his discoveries should have made him as famous
00:46as some of the other great electrical pioneers of history. People like Benjamin Franklin,
00:54Alessandro Volta, or even the great Michael Faraday.
00:59Quite unwittingly, he would set in motion a series of events that would revolutionise
01:06the Victorian world of brass and telegraph wire. This lecture would mark the birth of the modern
01:13electrical world, a world dominated by silicon, a mass wireless communication.
01:23In this programme, we discover how electricity connected the world together through broadcasting
01:31and computer networks, and how we finally learnt to unravel and exploit electricity at an atomic
01:39level. After centuries of man's experiments with electricity, a new age of real understanding
01:49was now dawning.
01:52In this programme, we'll see you next time.
02:00In this programme, we'll see you next time.
02:05In this programme, we'll see you next time.
02:19They'll see you next time in a minute.
02:22It's electricity's invisible effect, an effect not just confined to the wires it flows through.
02:30In the middle of the 19th century, a great theory was proposed to explain how this could be.
02:39The theory says that surrounding any electric charge,
02:43and there's a lot of electricity flowing above my head,
02:46is a force field.
02:48These fluorescent tubes are lit purely because
02:53they're under the influence of the force field
02:55from the power cables above.
03:00The theory that a flow of electricity
03:03could in some way create an invisible force field
03:06was originally proposed by Michael Faraday,
03:09but it would take a brilliant young Scotsman
03:13called James Clerk Maxwell, who would prove Faraday correct,
03:18and not through experimentation, but through mathematics.
03:23This was all a far cry from the typical 19th-century way
03:28of understanding how the world works,
03:31which was essentially to see it as a physical machine.
03:42Before Maxwell, scientists had often built strange machines
03:46or devised wondrous experiments to create and measure electricity.
03:52But Maxwell was different.
03:55He was interested in the numbers,
03:57and his new theory not only revealed electricity's invisible force field,
04:02but how it could be manipulated.
04:05It would prove to be one of the most important scientific discoveries of all time.
04:11Maxwell was a mathematician, and a great one,
04:14and he saw electricity and magnetism in an entirely new way.
04:17He expressed it all in terms of very compact mathematical equations.
04:21And the most important thing is that in Maxwell's equations
04:25is an understanding of electricity and magnetism
04:29as something linked and as something that can occur in waves.
04:42Maxwell's calculations showed how these fields could be disturbed,
04:47rather like touching the surface of water with your finger,
04:52changing the direction of the electric current
04:54would create a ripple or wave through these electric and magnetic fields.
05:00And constantly changing the direction of the flow of the current,
05:04forwards and backwards, like an alternating current,
05:08would produce a whole series of waves.
05:12Waves that would carry energy.
05:17Maxwell's maths was telling him that changing electric currents
05:21would be constantly sending out great waves of energy into their surroundings.
05:26Waves that would carry on forever unless something absorbed them.
05:43Maxwell's maths was so advanced and complicated
05:47that only a handful of people understood it at the time.
05:51And although his work was still only a theory,
05:54it inspired a young German physicist called Heinrich Hertz.
06:00Hertz decided to dedicate himself to designing an experiment
06:04to prove that Maxwell's waves really existed.
06:10And here it is.
06:12This is Hertz's original apparatus.
06:16And its beauty is in its sheer simplicity.
06:20He generates an alternating current that runs along these metal rods
06:25with a spark that jumps across the gap between these two spheres.
06:29Now, if Maxwell was right, then this alternating current
06:34should generate an invisible electromagnetic wave
06:37that spreads out into the surroundings.
06:40If you place a wire in the path of that wave,
06:44then at the wire there should be a changing electromagnetic field
06:49which should induce an electric current in the wire.
06:54So what Hertz did was build this ring of wire, his receiver,
06:59that he could carry around in different positions in the room
07:02to see if he could detect the presence of the wave.
07:05And the way he did that was leave a very tiny gap in the wire
07:11across which a spark would jump if a current runs through the ring.
07:16Now, because the current is so weak, that spark is very, very faint.
07:22And Hertz spent pretty much most of 1887 in a darkened room
07:28staring intensely through a lens
07:30to see if he could detect the presence of this faint spark.
07:42But Hertz wasn't alone in trying to create Maxwell's waves.
07:48Back in England, a young physics professor called Oliver Lodge
07:52had been fascinated by the topic for years,
07:55but hadn't had the time to design any experiments
07:59to try to discover them.
08:02Then, one day in early 1888,
08:06while setting up an experiment on lightning protection,
08:09he noticed something unusual.
08:15Lodge noticed that when he set up his equipment
08:18and sent an alternating current around the wires,
08:22he could see glowing patches between the wires.
08:26And with a bit of tweaking,
08:28he saw these glowing patches formed a pattern.
08:31The blue glow and electrical sparks occurred in distinct patches
08:36evenly spaced along the wires.
08:39He realised they were the peaks and troughs of a wave,
08:43an invisible electromagnetic wave.
08:46Lodge had proved that Maxwell was right.
08:51Finally, by accident,
08:53Lodge had created Maxwell's electromagnetic waves around the wires.
08:59The big question had been answered.
09:04Filled with excitement at his discovery,
09:07Lodge prepared to announce it to the world
09:09at that summer's annual scientific meeting
09:12run by the British Association.
09:16Before it, though, he decided to go on holiday.
09:20His timing couldn't have been worse,
09:23because back in Germany, and at exactly the same time,
09:27Heinrich Hertz was also testing Maxwell's theories.
09:36Eventually, Hertz found what he was looking for, a minute spark.
09:42And as he carried his receiver around to different positions in the room,
09:46he was able to map out the shape of the waves being produced by his apparatus.
09:51And he checked each of Maxwell's calculations carefully and tested them experimentally.
09:58It was a tour de force of experimental science.
10:06Back in Britain, as the crowds gathered for the British Association meeting,
10:11Oliver Lodge returned from holiday, relaxed and full of anticipation.
10:21This, Lodge thought, would be his moment of triumph,
10:25when he could announce his discovery of Maxwell's waves.
10:28His great friend, the mathematician Fitzgerald,
10:32was due to give the opening address in the meeting.
10:35But in it, he proclaimed that Heinrich Hertz had just published astounding results.
10:41He had detected Maxwell's waves travelling through space.
10:46We have snatched the thunderbolt from Jove himself
10:50and enslaved the all-pervading ether, he announced.
10:55Well, I can only imagine how Lodge must have felt having his thunder stolen.
11:02Professor Oliver Lodge had lost his moment of triumph,
11:07pipped at the post by Heinrich Hertz.
11:11Hertz is a spectacular demonstration of electromagnetic waves,
11:14what we now call radio waves.
11:15Even though he didn't know it at the time,
11:17it's going to lead to a whole revolution in communications over the next century.
11:26Maxwell's theory had shown how electric charges could create a force field around them,
11:32and that waves could spread through these fields like ripples on a pond.
11:39And Hertz had built a device that could actually create and detect the waves as they pass through the air.
11:48But almost immediately, there would be another revelation in our understanding of electricity.
11:54A revelation that would once again involve Professor Oliver Lodge.
11:59And once again, his thunder would be stolen.
12:16The story starts in Oxford in the summer of 1894.
12:21Hertz had died suddenly earlier that year,
12:24and so Lodge prepared a memorial lecture with a demonstration that would bring the idea of waves to a wider
12:32audience.
12:34Lodge had worked on his lecture.
12:36He'd researched better ways of detecting the waves,
12:40and he'd borrowed new apparatus from friends.
12:44He'd made some significant advances in the technology designed to detect the waves.
12:51This bit of apparatus generates an alternating current and a spark across this gap.
12:59The alternating current sends out an electromagnetic wave,
13:04just as Maxwell predicted, that is picked up by the receiver.
13:08It sets off a very weak electric current through these two antennae.
13:13Now, this is what Hertz had done.
13:16Lodge's improvement on this was to set up this tube full of iron filings.
13:22The weak electric current passes through the filings, forcing them to clump together.
13:27And when they do, they close a second electric circuit and set off the bell.
13:32So if I push the button on this end, it sets off the bell at the receiver.
13:39And it's doing that with no connections between the two.
13:43It's like magic.
13:50You could imagine a packed house, lots of people in the audience,
13:54and what they suddenly see is, as if by magic, a bell ringing.
14:02It's quite incredible.
14:05It might not have been the most dramatic demonstration the audience had ever seen,
14:10but it certainly still created a sensation among the crowd.
14:14Lodge's apparatus laid out like this no longer looked like a scientific experiment.
14:19In fact, it looked remarkably like those telegraph machines that had revolutionized communication,
14:27but without those long cables stretching between the sending and receiving stations.
14:33To the more worldly and savvy members of the audience,
14:37this was clearly more than showing the maestro Maxwell was right.
14:42This was a revolutionary new form of communication.
14:51Lodge published his lecture notes on how electromagnetic waves could be sent and received,
14:57using his new improvements.
15:00All around the world, inventors, amateur enthusiasts and scientists,
15:05read Lodge's reports with excitement and began experimenting with Hertzian waves.
15:14Two utterly different characters were to be inspired by it.
15:18Both would bring improvements to the wireless telegraph,
15:23and both would be remembered for their contribution to science far more than Oliver Lodge.
15:29The first was Guglielmo Marconi.
15:34Marconi was a very intelligent, astute and a very charming individual.
15:38He definitely had the Italian-Irish charm.
15:41He could apply this to almost anyone, from sort of young ladies to world-renowned scientists.
15:49Marconi was no scientist, but he read all he could of other people's work
15:54in order to put together his own wireless telegraph system.
15:58And it's possible that because he was brought up in Bologna and it was fairly close to the Italian coast,
16:04that he saw the potential of wireless communications in relation to maritime usage fairly early on.
16:11Then, aged only 22, he came to London with his Irish mother to market it.
16:20The other person, inspired by Lodge's lecture, was a teacher at the Presidency College in Calcutta,
16:27called Jagadish Chandra Bose.
16:32Despite degrees from London and Cambridge, the appointment of an Indian as a scientist in Calcutta
16:38had been a battle against racial prejudice.
16:44Indians, it was said, didn't have the requisite temperament for exact science.
16:49Well, Bose was determined to prove this wrong,
16:52and here in the archives we can see just how fast he's set to work.
16:58This is a report of the 66th meeting of the British Association in Liverpool, September 1896.
17:07And here is Bose, the first Indian ever to present at the association meeting,
17:13talking about his work and demonstrating his apparatus.
17:17He'd built and improved on the detector that Lodge described,
17:21because in the hot, sticky Indian climate,
17:25he'd found that the metal filings inside the tube that Lodge used to detect the waves became rusty and stuck
17:31together.
17:32So Bose had to build a more practical detector using a coiled wire instead.
17:38His work was described as a sensation.
17:43The detector was extremely reliable and could work on board ships, so had great potential for the vast British naval
17:50fleet.
17:52Britain was the centre of a vast telecommunications network which stretched almost around the world,
17:58which was used to support an equally vast maritime network of merchant and naval vessels which were used to support
18:07the British Empire.
18:08But Bose, a pure scientist, wasn't interested in the commercial potential of wireless signals, unlike Marconi.
18:18This was sort of a new, cutting edge field, but Marconi wasn't a trained scientist, so he did come at
18:26things in a fairly different way,
18:27which may have been why he progressed so quickly in the first place.
18:30And he was very good at forming connections with the people that he needed to form connections with to enable
18:38his work to be done.
18:41Marconi used his connections to go straight to the only place that had the resources to help him.
18:51The British Post Office was a hugely powerful institution.
18:55When Marconi first arrived in London in 1896, these buildings were newly completed and already heaving with business from the
19:05Empire's postal and telegraphy services.
19:09Marconi had brought his telegraph system with him from Italy, claiming it could send wireless signals over unheard of distances.
19:17And the post office engineer in chief, William Preece, immediately saw the technology's potential.
19:26So Preece offered Marconi the great financial and engineering resources of the post office, and they started work up on
19:35the roof.
19:38The old headquarters of the post office were right there, and between this roof and that one, Marconi and the
19:45post office engineers would practice sending and receiving electromagnetic waves.
19:51The engineers helped him improve his apparatus, and then Preece and Marconi, together, demonstrated it to influential people in government
20:00and the navy.
20:04What Preece didn't realise was that even as he was proudly announcing Marconi's successful partnership with the post office, Marconi
20:14was making plans behind the scenes.
20:18He'd applied for a British patent on the whole field of wireless telegraphy and was planning on setting up his
20:25own company.
20:27When the patent was granted, all hell broke loose in the scientific community.
20:36That patent was itself revolutionary.
20:43You see, patents could only be taken out on things that weren't public knowledge.
20:48But Marconi famously had hidden his equipment in a secret box.
20:57And here it is.
20:59When his patent was finally granted, Marconi ceremoniously opened the box.
21:06Everyone was keen to see what inventions lay within.
21:13Batteries forming a circuit, iron filings in the tube to complete the circuit to ring the bell on top.
21:20Nothing they hadn't seen before.
21:23And yet Marconi had patented the lot.
21:28The reason why Marconi is famous is not because of that invention.
21:32He doesn't invent radio, but he improves it and turns it into a system.
21:37Lodge doesn't do that.
21:39And that's why we remember Marconi and that's why we don't remember Lodge.
21:48The scientific world was up in arms.
21:51He was this young man who knew very little about the science behind his equipment,
21:56about to make his fortune from their work.
22:00Even his great supporter, Preece, was disappointed and hurt when he found out that Marconi was about to go Italy.
22:07He didn't know his own and set up his own company.
22:09Lodge and other scientists began a frenzy of patenting every tiny detail and improvement they made to their equipment.
22:21This new atmosphere shocked Bos when he returned to Britain.
22:27Bos wrote home to India in disgust at what he found in England.
22:33Money, money, money, all the time. What a devouring greed.
22:37I wish you could see the craze for money of the people here.
22:43His disillusionment with the changes he saw in the country he revered for its scientific integrity and excellence is palpable.
22:53Eventually, though, it was his friends who convinced Bos to take out his one and only patent on his discovery
23:01of a new kind of detector for waves.
23:04It was this discovery that would lead to perhaps an even greater revolution for the world.
23:09He had discovered the power of crystals.
23:16This replaces older techniques using iron filings which are messy and difficult and don't work well.
23:21And here's a whole new way of detecting radio waves and it's one that's going to be at the centre
23:26of a radio industry.
23:29Bos's discovery was simple, but it would truly shape the modern world.
23:36When some crystals are touched with metal to test their electrical conductivity, they can show rather odd and varied behaviour.
23:46Take this crystal, for example.
23:48If I can touch it in exactly the right spot with the tip of this metal wire and then hook
23:55it up to a battery, it gives quite a significant current.
24:01But if I switch around my connections to the battery and try and pass the current through in the opposite
24:06direction, it's a lot less.
24:12It's not a full conductor of electricity. It's a semiconductor and it found its first use in detecting electromagnetic waves.
24:24When Bose used a crystal like this in his circuits instead of the tube of filings, he found it was
24:30a much more efficient and effective detector of electromagnetic waves.
24:36It was this strange property of the junction between the wire, known as the cat's whisker, and the crystal, which
24:45allowed current to pass much more easily in one direction than the other, that meant it could be used to
24:51extract a signal from electromagnetic waves.
24:56At the time, no one had any idea why certain crystals acted in this way.
25:02But to scientists and engineers, the strange behaviour had a profound and almost miraculous practical effect.
25:13With crystals as detectors, now it was possible to broadcast and detect the actual sound of a human voice or
25:24music.
25:35In his Oxford lecture in 1894, Oliver Lodge had opened a Pandora's box.
25:42As an academic, he'd failed to foresee that the scientific discoveries he'd been such a part of had such commercial
25:50potential.
25:52The one patent he had managed to secure, the crucial means of tuning a receiver to a particular radio signal,
25:59was bought off him by Marconi's powerful company.
26:09Perhaps the worst indignation for Lodge, though, would come in 1909, when Marconi was awarded the Nobel Prize in Physics
26:18for wireless communication.
26:21It's difficult to imagine a bigger snub to the physicist who'd so narrowly missed out to Hertz in the discovery
26:28of radio waves, and who'd then go on to show the world how they could be sent and received.
26:36But despite this snub, Lodge remained magnanimous, using the new broadcasting technology that resulted from his work to give credit
26:45to others, as this rare film of him shows.
26:49Hertz made a great advance. He discovered how to produce and detect waves in space, thus bringing the ether into
26:59practical use, harnessing it for the transmission of intelligence in a way which has subsequently been elaborated by a number
27:08of people.
27:21Today, we can hardly imagine a world without broadcasting, to imagine a time when radio waves hadn't even been dreamt
27:29of.
27:31Engineers continued to refine and perfect our ability to transmit and receive electromagnetic waves.
27:38But their initial discovery was ultimately a triumph of pure science, from Maxwell through Hertz to Lodge.
27:48But still, the very nature of electricity itself remained unexplained.
27:53What created those electrical charges and currents in the first place?
28:00Although scientists were learning to exploit electricity, they still didn't know what it actually was.
28:08But this question was being answered, with experiments looking into how electricity flowed through different materials.
28:16Back in the 1850s, one of Germany's great experimentalists and a talented glassblower, Heinrich Geisler, created these beautiful showpieces.
28:37Geisler pumped most of the air out of these intricate glass tubes and then had small amounts of other gases
28:44pumped in.
28:48He then passed an electrical current through them.
28:52They glowed with stunning colours, and the current flowing through the gas seemed tangible.
29:01Although they were designed purely for entertainment, over the next 50 years scientists saw Geisler's tubes as a chance to
29:09study how electricity flowed.
29:14Efforts were made to pump more and more air out of the tubes.
29:18Could the electric current pass through nothingness, through the vacuum?
29:28This is a very rare flick book film of the British scientist who created a vacuum good enough to answer
29:37that question.
29:38His name was William Crookes.
29:43Crookes created tubes like this.
29:45He pumped out as much of the air as he could, so that it was as close to a vacuum
29:50as he could make it.
29:52Then, when he passed an electric current through the tube...
29:58..he noticed a bright glow on the far end.
30:02A beam seemed to be shining through the tube and hitting the glass at the other end.
30:08It seemed at last we could see electricity.
30:11The beam became known as a cathode ray.
30:14And this tube was the forerunner of the cathode ray tube that was used in television sets for decades.
30:27Physicist JJ Thomson discovered that these beams were made up of tiny, negatively charged particles.
30:35And because they were carriers of electricity, they became known as electrons.
30:42Because the electrons only moved in one direction, from the heated metal plate through the positively charged plate at the
30:49other end,
30:49they behaved in exactly the same way as Bose's semiconductor crystals.
30:55But whereas Bose's crystals were naturally temperamental, you had to find the right spot for them to work.
31:02These tubes could be manufactured consistently.
31:06They became known as valves, and they soon replaced crystals in radio sets everywhere.
31:17These discoveries would lead to an explosion of new technology.
31:22Early 20th century electronics is all about what you can do with valves.
31:27So the radio industry is built on valves, early television is built on valves, early computers are built with valves.
31:34These are the things that you build the electronic world with.
31:39These are the things that you build the electronic world with.
31:40Having discovered how to manipulate electrons flowing through a vacuum,
31:44scientists were now keen to understand how they could flow through other materials.
31:50But that meant understanding the things that made up materials, atoms.
32:07It was in the early years of the 20th century that we finally got a handle on exactly what atoms
32:15were made up of and how they behaved.
32:17And so what electricity actually was on the atomic scale.
32:25At the University of Manchester, Ernest Rutherford's team were studying the inner structure of the atom,
32:31and producing a picture to describe what an atom looked like.
32:35This revelation would finally help explain some of the more puzzling features of electricity.
32:42By 1913, the picture of the atom was one in which you had a positively charged nucleus in the middle,
32:50surrounded by negatively charged orbiting electrons in patterns called shells.
32:56Each of these shells corresponded to an electron with a particular energy.
33:02Now, given an energy boost, an electron could jump from an inner shell to an outer one.
33:08And the energy had to be just right.
33:10If it wasn't enough, the electron wouldn't make the transition.
33:14And this boost was often temporary because the electron would then drop back down again to its original shell.
33:21As it did this, it had to give off its excess energy by spitting out a photon.
33:28And the energy of each photon depended on its wavelength, or as we would perceive it, its colour.
33:39Understanding the structure of atoms could now also explain nature's great electrical light shows.
33:48Just like geyserless tubes, the type of gas the electricity passes through defines its colour.
33:57Lightning has a blue tinge because of the nitrogen in our atmosphere.
34:04Higher in the atmosphere, the gases are different.
34:08And so is the colour of the photons they produce, creating the spectacular auroras.
34:20Understanding atoms, how they fit together in materials and how their electrons behave,
34:26was the final key to understanding the fundamental nature of electricity.
34:38This is a Winshurst machine, and it's used to generate electric charge.
34:45Electrons are rubbed off these discs and start a flow of electricity through the metal arms of the machine.
34:55Now, metals conduct electricity because the electrons are very weakly bound inside their atoms,
35:01and so can slosh about and be used to flow as electricity.
35:06Insulators, on the other hand, don't conduct electricity because the electrons are very tightly bound inside the atoms,
35:12and are not free to move about.
35:16The flow of electrons, and hence electricity, through materials was now understood.
35:22Conductors and insulators could be explained.
35:26What was more difficult to understand was the strange properties of semiconductors.
35:34Our modern electronic world is built upon semiconductors, and would grind to a halt without them.
35:43Jagadish Chandra Bose may have stumbled upon their properties back in the 1890s,
35:48but no-one could have foreseen just how important they were to become.
35:55But with the outbreak of the Second World War, things were about to change.
36:05Here in Oxford, this newly built physics laboratory was immediately handed over to the war research efforts.
36:13The researchers here were tasked with improving the British radar system.
36:22The radar was a technology that used electromagnetic waves to detect enemy bombers.
36:29And as its accuracy improved, it became clear that valves just weren't up to the job.
36:39So the team had to turn to old technology.
36:42Instead of valves, they used semiconductor crystals.
36:47Now, they didn't use the same sort of crystals that Bose had developed.
36:50Instead, they used silicon.
36:55This device is the silicon crystal receiver.
37:00There's a tiny tungsten wire coiled down and touching the surface of a little silicon crystal.
37:07It's incredible how important a device it was.
37:14It was the first time silicon had really been exploited as a semiconductor.
37:20But for it to work, it needed to be very pure.
37:24And both sides in the war put a lot of resources into purifying it.
37:30In fact, the British had better silicon devices, so they must have had some growth of silicon already at that
37:38time, which we were just started with, you know, in Berlin.
37:44The British had better silicon semiconductors because they had help from laboratories in the US, in particular the famous Bell
37:53Labs.
37:54And it wasn't long before physicists realised that if semiconductors could replace valves in radar, perhaps they could replace valves
38:03in other devices too, like amplifiers.
38:09The simple vacuum tube with its one-way stream of electrons had been modified to produce a new device.
38:17By placing a metal grill in the path of the electrons and applying a tiny voltage to it, a dramatic
38:23change in the strength of the beam could be produced.
38:26These valves worked as amplifiers, turning a very weak electrical signal into a much stronger one.
38:33An amplifier is something, in one sense, really simple. You just take a small current, you turn it into a
38:39larger current.
38:41But in other ways, it changes the world. Because when you can amplify a signal, you can send it anywhere
38:48in the world.
38:52As soon as the war was over, German expert Herbert Matteray and his colleague Heinrich Welker started to build a
39:01semiconductor device that could be used as an electrical amplifier.
39:06And here is that first working model that Matteray and here is that first working model that Matteray and Welker
39:12made.
39:13If you look inside, you can see the tiny crystal and the wires that make contact with it.
39:19If you pass a small current through one of the wires, this allows a much larger current to flow through
39:26the other one.
39:27So it was acting as a signal amplifier.
39:33These tiny devices could replace big, expensive valves in long-distance telephone networks, radios and other equipment where a faint
39:44signal needed boosting.
39:47Matteray immediately realised what he'd created, but his bosses were initially not interested.
39:52Not, that is, until a paper appeared in a journal announcing a Bell Labs discovery.
40:02A research team there had stumbled across the same effect and now they were announcing their invention to the world.
40:10They called it the transistor.
40:14They had it in December 1947 and we had it in beginning 48 and, but just, just, just, just life,
40:23you know.
40:25They had it a little bit earlier, the effect.
40:28But, funny enough, their transistors were just no good.
40:34Although the European device was more reliable than Bell Labs more experimental model, neither quite fulfilled their promise.
40:44They worked, but were just too delicate.
40:48So the search was on for a more robust way to amplify electrical signals.
40:53And the breakthrough came by accident.
40:58In Bell Labs, silicon crystal expert Russell Ohl noticed that one of his silicon ingots had a really bizarre property.
41:07It seemed to be able to generate its own voltage.
41:10And when he tried to measure this by hooking it up to an oscilloscope, he noticed that the voltage changed
41:16all the time.
41:18The amount of voltage it generated seemed to depend on how much light there was in the room.
41:24So, by casting a shadow over the crystal, he saw the voltage dropped.
41:30More light meant the voltage went up.
41:33What's more, when he turned a fan on between the lamp and the crystal,
41:39the voltage started to oscillate with the same frequency that the blades of the fan were casting shadows over the
41:48crystal.
41:52One of Ohl's colleagues immediately realised that the ingot had a crack in it that formed a natural junction.
41:59And this tiny, natural junction in an otherwise solid block was acting just like the much more delicate junction between
42:08the end of a wire and a crystal that Bose had discovered.
42:13Except here, it was sensitive to light.
42:18The ingot had cracked because either side contained slightly different amounts of impurities.
42:26One side had slightly more of the element phosphorus, while the other had slightly more of a different impurity, boron.
42:35And electrons seemed to be able to move across from the phosphorus side to the boron side, but not vice
42:42versa.
42:43Photons of light shining down onto the crystal were knocking electrons out of the atoms.
42:48But it was the impurity atoms that were driving this flow.
42:52So, the other, the other, the other, the other.
42:55Phosphorus has an electron that is going spare,
42:59and boron is keen to accept another.
43:02So electrons tended to flow from the phosphorus side to the boron side,
43:08and crucially, only flowed one way across the junction.
43:18The head of the semiconductor team, William Shockley, saw the potential of this one-way junction within a crystal.
43:26But how would it be possible to create a crystal with two junctions in it that could be used as
43:32an amplifier?
43:35Another researcher at Bell Labs called Gordon Teal had been working on a technique that would allow just that.
43:45He'd discovered a special way to grow single crystals of the semiconductor germanium.
43:55In this research institute, they grow semiconductor crystals in the same way that Teal did back in Bell Labs.
44:02Only here, they grow them much, much bigger.
44:09At the bottom of this vat is a container with glowing hot molten germanium, just as pure as you can
44:18get it.
44:19Inside it are a few atoms of whatever impurity is required to alter its conductive properties.
44:26Now, the rotating arm above has a seed crystal at the bottom that has been dipped into the liquid and
44:34will be slowly raised up again.
44:41As the germanium cools and hardens, it forms a long crystal like an icicle below the seed.
44:49The whole length is one single beautiful germanium crystal.
45:01Teal worked out that as the crystal is growing, other impurities can be added to the vat and mixed in.
45:09This gives us a single crystal with thin layers of different impurities, creating junctions within the crystal.
45:26This crystal with two junctions in it was Shockley's dream.
45:32Applying a small current through the very thin middle section allows a much larger current to flow through the whole
45:39triple sandwich.
45:44From a single crystal like this, hundreds of tiny solid blocks could be cut, each containing the two junctions that
45:54would allow the movement of electrons through them to be precisely controlled.
46:01These tiny and reliable devices could be used in all sorts of electrical equipment.
46:07You cannot have the electronic equipment that we have without tiny components.
46:12You get a weird effect, actually. The smaller they get, the more reliable they get. It's a win-win situation.
46:20The Bell Labs team were awarded the Nobel Prize for their world-changing invention, while the European team were forgotten.
46:34William Shockley left Bell Labs and in 1955 set up his own semiconductor laboratory in rural California, recruiting the country's
46:44best physics graduates.
46:46But the celebratory mood didn't last long, because Shockley was almost impossible to work for.
46:53People left his company because they just disliked the way he treated them.
47:00So the fact that Shockley was actually such a git is why you have Silicon Valley.
47:06It starts that whole process of spin-off and growth and new companies, and it all starts off with Shockley
47:14being such a shocking human being.
47:27The new companies were in competition with each other to come up with the latest semiconductor devices.
47:34They made transistors so small that huge numbers of them could be incorporated into an electrical circuit printed on a
47:42single slice of semiconductor crystal.
47:48These tiny and reliable chips could be used in all sorts of electrical equipment, most famously in computers.
47:58A new age had dawned.
48:11Today, microchips are everywhere.
48:14They've transformed almost every aspect of modern life, from communication to transport and entertainment.
48:22But perhaps just as importantly, our computers have become so powerful they're helping us to understand the universe in all
48:31its complexity.
48:36A single microchip like this one today can contain around 4 billion transistors.
48:44It's incredible how far technology has come in 60 years.
48:52It's easy to think that with the great leaps we've made in understanding and exploiting electricity, there's little left to
49:00learn about it.
49:03But we'd be wrong.
49:06For instance, making the circuits smaller and smaller meant that a particular feature of electricity that had been known about
49:14for over a century was becoming more and more problematic.
49:19Resistance.
49:24A computer chip has to be continuously cooled.
49:27If you take away the fan, this is what happens.
49:32Wow, that's shooting up.
49:35100, 120, 130 degrees.
49:42200 degrees and it cut out.
49:45That just took a few seconds and the chip is well and truly cooked.
49:50You see, as the electrons flow through the chip, they're not just travelling around unimpeded.
49:56They're bumping into the atoms of silicon.
49:59And the energy being lost by these electrons is producing heat.
50:05Now, sometimes this was useful.
50:07Inventors made electric heaters and ovens.
50:10And whenever they got something to glow white hot, well, that's a light bulb.
50:15But resistance in electronic apparatus and in power lines is the major waste of energy.
50:22And a huge problem.
50:28It's thought that resistance wastes up to 20% of all the electricity we generate.
50:36It's one of the greatest problems of modern times.
50:40And the search is on for a way to solve the problem of resistance.
50:50What we think of as temperature is really a measure of how much the atoms in the material are vibrating.
50:58And if the atoms are vibrating, then electrons flowing through are more likely to bump into them.
51:05So, in general, the hotter the material, the higher its electrical resistance.
51:09And the cooler it is, the lower the resistance.
51:12But what happens if you cool something right down, close to absolute zero, minus 273 degrees Celsius?
51:22Well, at absolute zero, there's no heat at all.
51:25And so the atoms aren't moving at all.
51:29What happens then to the flow of electricity, the flow of electrons?
51:37Using a special device called a cryostat that can keep things close to absolute zero, we can find out.
51:46Inside this cryostat, in this coil, is mercury, the famous liquid metal.
51:52And it forms part of an electric circuit.
51:54Now, this equipment here measures the resistance in the mercury.
51:59But look what happens as I lower the mercury into the coldest part of the cryostat.
52:09There it is.
52:10The resistance has dropped to absolutely nothing.
52:14Mercury, like many substances we now know, have this property.
52:18It's called becoming superconducting, which means they have no resistance at all to the flow of electricity.
52:26But these materials only work when they're very, very cold.
52:32If we could use a superconducting material in our power cables and in our electronic apparatus,
52:38we'd avoid losing so much of our precious electrical energy through resistance.
52:47The problem, of course, is that superconductors had to be kept at extremely low temperatures.
52:54Then, in 1986, a breakthrough was made.
53:00In a small laboratory near Zurich, Switzerland, IBM physicists recently discovered her superconductivity in a new class of materials
53:08that is being called one of the most important scientific breakthroughs in many decades.
53:15This is a block of the same material made by the researchers in Switzerland.
53:20It doesn't look very remarkable, but if you cool it down with liquid nitrogen, something special happens.
53:26It becomes a superconductor.
53:30And because electricity and magnetism are so tightly linked, that gives it equally extraordinary magnetic properties.
53:38This magnet is suspended, levitating above the superconductor.
53:47The exciting thing is that, although cold, this material is way above absolute zero.
54:05These magnetic fields are so strong that not only can they support the weight of this magnet, but they should
54:12also support my weight.
54:14I'm about to be levitated.
54:18Oh, it's a very, very strange sensation.
54:25When this material was first discovered in 1986, it created a revolution.
54:31Not only had no one considered that it might be superconducting, but it was doing so at a temperature much
54:38warmer than anyone had thought possible.
54:41We are tantalisingly close to getting room temperature superconductors.
54:45We're not there yet, but one day a new material will be found.
54:49And when we put that into our electronics equipment, we could build a cheaper, better, more sustainable world.
54:58Today, materials have been produced that exhibit this phenomenon at the sort of temperatures you get in your freezer.
55:06But these new superconductors can't be fully explained by the theoreticians.
55:10So, without a complete understanding, experimentalists are often guided as much by luck as they are by a proper scientific
55:19understanding.
55:22Recently, a laboratory in Japan held a party in which they ended up dosing their superconductors with a range of
55:29alcoholic beverages.
55:31Unexpectedly, they found that red wine improves the performance of the superconductors.
55:40Electrical research now has the potential once again to revolutionise our world if room temperature superconductors can be found.
56:01Our addiction to electricity's power is only increasing.
56:07And when we fully understand how to exploit superconductors, a new electrical world will be upon us.
56:14It's going to lead to one of the most exciting periods of human discovery and invention.
56:20A brand new set of tools, techniques and technologies to once again transform the world.
56:35Electricity has changed our world.
56:38Only a few hundred years ago, it was seen as a mysterious and magical wonder.
56:44Then, it leapt out of the laboratory with a series of strange and wondrous experiments, eventually being captured and put
56:54to use.
56:55It revolutionised communication, first through cables and then as waves through electricity's far-reaching fields.
57:05It powers and lights the modern world.
57:09Today, we can hardly imagine life without electricity.
57:12It defines our era and we will be utterly lost without it.
57:20And yet, it still offers us more.
57:23We stand once again at the beginning of a new age of discovery.
57:28A new revolution.
57:36But above all else, there's one thing that all those who deal in the science of electricity know.
57:43Its story is not over yet.
58:05To find out more about the story of electricity and to put your power knowledge to the test, try the
58:11Open University's interactive energy game.
58:14Go to bbc.co.uk forward slash electricity and follow links to the Open University.
58:28A ringside seat for the changing of the seasons in Autumn Watch back here on BBC HD from half past
58:33eight tomorrow night.
58:34And coming up next, we're off to the seaside with Coast.
58:47See you then!
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