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00:00.
00:06Electricity is one of nature's greatest forces.
00:11And by the middle of the 20th century,
00:14we'd harnessed it to light and power our modern world.
00:21Hundreds of years of scientific discoveries and inventions
00:24brought us here.
00:25But it would take the eccentric genius of one man
00:30to unlock the full potential of electrical power.
00:35In the winter of 1943,
00:39Nikola Tesla looked out across the Manhattan skyline
00:43for the very last time.
00:45Tesla had been born into a world powered by steam
00:49and lit by gas.
00:51But before his eyes, he saw a new world.
00:55A world transformed.
00:57A world powered by electricity.
01:00His world.
01:08Frail, lonely and still mourning the death of one of his beloved pigeons,
01:13this extraordinary and eccentric genius knew that his life's work was done.
01:19And he laid back on his bed to die.
01:23It will be three days before anyone found his body.
01:38Just over 200 years ago,
01:41early scientists discovered electricity could be much more than simply a static charge.
01:48It could be made to flow in a continuous current.
01:57But they were about to discover something profound.
02:01That electricity is connected to magnetism.
02:06Harnessing the link between magnetism and electricity would completely transform the world
02:13and allow us to generate seemingly limitless amounts of electrical power.
02:26This is the story of how scientists and engineers unlocked the nature of electricity
02:32and then used it in an extraordinary century of innovation and invention.
02:40But not before one of the most shocking engineering rivalries in history was finally laid to rest.
03:03Our story begins in London at the beginning of the 19th century,
03:08with a young man who would further our understanding of electricity as much as any other.
03:14On the 29th of February, 1812,
03:17a 20-year-old self-educated bookbinder called Michael Faraday
03:22came here to the Royal Institution of Great Britain.
03:34He was surrounded by the great and the good of the academic world
03:38and he was about to listen to one of the greatest scientific minds of the age.
03:47Faraday, the son of a blacksmith, had finished his formal education when he was just 12 years old.
03:54He would never get to university.
03:56But he wasn't finished with learning, as he was fascinated by science.
04:04Faraday worked long and hard during the day binding books.
04:08But in the evenings, he would read whatever scientific literature he could lay his hands on.
04:15He loved learning new things about the world.
04:18And he had this constant desire, this passion, to understand why things were the way they were.
04:29Reading scientific papers was one thing.
04:32But to really satisfy his craving for knowledge,
04:36Faraday was desperate to see the experiments themselves.
04:39And he eventually got his chance when he was given a ticket to attend one of the last lectures
04:45of England's greatest chemist of the time, Sir Humphrey Davy.
04:53It was to change young Faraday's life forever.
05:00After watching Davy, awe inspired and full of ideas,
05:04Faraday knew what he wanted to do with his life.
05:07He was determined to dedicate himself to furthering science.
05:13And that's just what he did.
05:16Within a year, Davy had appointed him as an assistant at the Royal Institution.
05:23With Davy as his patron and, well, his boss,
05:27Faraday studied all manner of chemistry.
05:31But what would inspire his greatest breakthroughs?
05:34With the invisible forces of electricity and magnetism.
05:43In 1820, both were being studied by a Danish scientist,
05:48Hans Christian Ørsted, who'd made an extraordinary discovery.
05:55He passed an electric current through a copper rod
05:59and brought it close to a magnetic compass needle
06:02and saw that it made the needle rotate.
06:07To Ørsted, it was remarkable.
06:09He'd shown, for the first time,
06:12that an electric current can create a magnetic force.
06:16He'd bound electricity and magnetism together.
06:21Today, we call it electromagnetism,
06:24and it's one of the fundamental forces of nature.
06:28Ørstedís discovery sparks off a whole new spate of inventive activity
06:35around and about the fields of electricity.
06:39You can almost see electrical experimenters vying,
06:43competing with each other to find new links
06:46between electricity and the other powers of nature.
06:49At the Royal Institution,
06:51Faraday set about recreating Ørstedís work,
06:55which would mark his first steps to fame and fortune.
07:00And through his rigorous research,
07:02he concluded that there must be a flow of forces
07:06acting between the wire and the compass needle.
07:09The device he designed to demonstrate it
07:12would change the course of history.
07:16Faraday created a circuit using a battery like this,
07:21a pair of wires, and a mercury bath.
07:24Now, the circuit carries on through these copper posts,
07:28and this wire hangs freely.
07:30It dangles into the mercury.
07:32Now, because mercury is such a good conductor,
07:35it completes the circuit.
07:38When the current runs through the circuit,
07:43it generates a circular magnetic force field around the wire.
07:48Now, this interacts with the magnetism from a permanent magnet
07:52that Faraday had placed in the middle of the mercury.
07:55Together, they force the wire to move.
07:59Faraday had proved that this invisible force really does exist,
08:04and he could see its effect, circular motion.
08:07This beautiful device was the first to convert electric current
08:13into continuous motion.
08:15Basically, it's the earliest ever electric motor.
08:25But Faraday was about to take this experiment further.
08:32One of the lasting effects of Faraday's discovery
08:35of electromagnetic rotations in 1821
08:38was that it showed that there was a relationship of some sort
08:41between electricity, magnetism and motion.
08:47Faraday explored this relationship in detail,
08:50and set himself an even more difficult challenge.
08:55To use magnetism and motion to make electricity.
09:03Eventually, his obsession, hard work and determination paid off.
09:10The breakthrough came on 17 October 1831,
09:15when Faraday took a magnet like this
09:19and moved it in and out of a coil of wire.
09:23He was able to detect a tiny electric current in the coil,
09:29moving one way...
09:32..and then the other.
09:38Faraday knew he was onto something.
09:40A few days later, instead of moving the magnet
09:44through the conducting wire coil,
09:46he set up the equivalent experiment
09:48by moving a conducting copper plate
09:51through the magnetic field.
09:57He didn't know it at the time,
09:59but as his spinning disk cut through this magnetic field,
10:03billions of negatively charged electrons were deflected
10:07from their original circular course
10:09and began to drift towards the edge.
10:13A negative charge built up at the outer edge of the disk,
10:17leaving a positive charge at the centre.
10:20And once the disk was connected to wires,
10:23the electrons flowed in a steady stream.
10:27Faraday had generated a continuous flow of electric current.
10:33Unlike a battery, his current flowed for as long as his copper disc was spun.
10:39He'd created electrical power directly from mechanical power.
10:45Although Faraday's discovery of induction was extraordinarily important in its own right
10:49and had profound effects for the understanding of electricity and technology
10:55for the rest of the 19th century,
10:57for Faraday what it did was open up a decade of powerful research
11:03because it gave him the clue about how he should pursue his research.
11:08While Faraday continued his work trying to understand the very nature of electricity,
11:14inventors from across Europe were less interested in the science
11:18and more interested in how electricity could make them money.
11:23What's actually quite remarkable, certainly from a contemporary perspective,
11:27is that by and large nobody really seems to care very much what electricity is.
11:34You don't have great theoretical debates as to whether it's a force or a fluid
11:39or a principle or a power.
11:41What they're really interested in is what electricity can do.
11:47Faraday, living in a world of steam power, was informing the scientific community about the nature of electricity.
11:55But at the same time, another breakthrough in how we could actually use it had been made.
12:02This would be the first device that really brought electricity out of the laboratory
12:08and into the hands of ordinary people.
12:12The telegraph.
12:17The key to understanding the telegraph is understanding a special kind of magnet.
12:24An electromagnet.
12:25Basically, a magnet created by an electric current.
12:32The first electromagnets were developed independently by William Sturgeon in Britain
12:38and Joseph Henry in America.
12:40And just as Faraday had discovered that by coiling his wire, he could increase the current in it produced by
12:47the moving magnet,
12:48so Henry and Sturgeon discovered that by adding more coils in their current-carrying wires,
12:55they could make a more concentrated magnetic field.
12:59Basically, the more coils, the more turns, the stronger the magnet.
13:03So, if I pass a current through this electromagnet, you can actually see the effects of the magnetic field.
13:12This is the standard school experiment of sprinkling iron filings on top of the magnet.
13:18If I give it a tap, see the iron filings follow the contours of the field.
13:24This allows us to visualise the effects of magnetism.
13:30To make an electromagnet even stronger, Henry and Sturgeon discovered that they could place certain kinds of metal inside the
13:39electromagnetic coil.
13:41The reason iron is so effective is fascinating because you can think of it as being made up of lots
13:46of tiny magnets all pointing in random directions.
13:50At the moment, this is not a magnet.
13:53The tiny magnets inside are aligned similarly to these compass needles.
13:58If you see, they're all pointing in different directions.
14:00But when you apply a magnetic field, they all align together.
14:08They all combine these magnets and cumulatively, they add to the strength of the electromagnet.
14:14So, what Henry and Sturgeon did was place two electromagnetic coils on each arm of their horseshoe
14:22to create something that was many, many times more powerful.
14:31And we can see the power of this horseshoe electromagnet.
14:36If I turn it on and use something slightly bigger than iron filings, these small pieces of iron.
14:44Look at the strength of the magnetic field holding them in place.
14:49What's important to remember, of course, is that this electromagnet only works all the time as a current.
14:58As soon as I turn off the current, the magnetism disappears.
15:06Early experimenters showed off this power by lifting metal weights.
15:11Henry even made one big enough to lift a tonne and a half of metal.
15:17Impressive, but not world-changing.
15:19But place that magnet much further away, at the end of a wire, and suddenly you can make something happen
15:26at your command, in an instant.
15:33This ability to control a magnet at a distance is one of the most useful things we've ever discovered.
15:43If electricity can be made visible a long way away from the original source of power, then you've got a
15:51source of instantaneous communication.
15:56By the middle of the 1840s, Samuel Morse had developed a messaging system based on how long an electrical circuit
16:05was switched on or off.
16:08A long pulse of currents for a dash, a short burst for a dot.
16:12This allowed messages to be sent and received by using a simple code.
16:20Contemporary early Victorian commentators reflect on the fact that electricity and the telegraph is literally making their world a smaller
16:29place.
16:29You very often get a sort of rhetoric throughout the 19th century when people are talking about the telegraph about
16:36how more communication, more understanding will render war obsolete.
16:43Because we'll all understand each other better.
16:46I mean, retrospectively, it seems hopelessly utopian.
16:53By the 1850s, Europe and America were crisscrossed with land-based telegraph wires.
17:00But the dream of instant global communication was frustratingly out of reach.
17:07This was because there was still no cable capable of carrying messages between two of the greatest powers on Earth,
17:16Britain and America.
17:18Many experts were convinced that a working Atlantic cable was impossible.
17:24But those who disagreed knew that if they could solve this problem, it could make them serious money.
17:29And in the 1850s, American businessmen and British engineers joined forces to prove this could be done.
17:41Attempt after attempt ended in disaster.
17:44The heavy cables kept snapping in heavy seas and storms.
17:51Finally, on the 29th of July, 1858, two parts of a cable were spliced together in mid-Atlantic.
17:59You see, a single cable was simply too big to have been carried by one ship.
18:04Then one end was taken to Newfoundland and the other end to South West Ireland.
18:11Six days later, the first direct link between the two most powerful nations in the world was in place.
18:19The project was hailed a huge success and a formal message of congratulations was sent from Queen Victoria to President
18:28Buchanan.
18:30But before the celebrations were over, things started to go very wrong.
18:36This is Chief Engineer Bright's original notebook.
18:40You can see here Queen Victoria's original message.
18:44Now, it's only 98 words long, but it took 16 hours to transmit.
18:51The telegraph operators on the other side found it very hard to decipher the message.
18:57The electrical signals that they were receiving were blurred and distorted,
19:01and they kept asking for words to be repeated over and over again.
19:06So you can see here, repeat after sending, waiting to receive, no signals.
19:12Clearly, transmitting across the Atlantic wasn't going to be as straightforward as people had hoped.
19:20Over the next few days, several hundred messages were exchanged.
19:25But those arriving in Newfoundland became almost impossible to decipher.
19:30Just a jumbled mess of dots and dashes.
19:33There was a serious problem with the cable, and it was getting worse.
19:37Well, the 1858 cable was never fully repaired.
19:43And the end finally came when British engineer Wildman Whitehouse
19:48mistakenly believed that by increasing the signal voltage,
19:53he could force the messages through to Newfoundland.
19:56The cable simply stopped working altogether.
20:04At the time, increasing the voltage by using more powerful batteries made sense.
20:11Most experts believed electric current flowed through a cable like a fluid in a pipe.
20:18Increasing the voltage was the equivalent of increasing the pressure in the system,
20:24forcing the current through to the other end.
20:27But the telegraph was actually carrying pulses or ripples of current along the cable,
20:34not a continuous stream.
20:36And over long distances, these pulses were becoming distorted,
20:41making it difficult to tell what was a short dot and which was a longer dash.
20:47By studying the effectiveness of underwater cabling,
20:52scientists were beginning to understand that electric current
20:56didn't always flow like water,
20:58but was also creating invisible electromagnetic waves or ripples.
21:04And it's this breakthrough that would lead to a new branch of research
21:10into the electromagnetic spectrum
21:12and solve the problems of the Atlantic Telegraph.
21:17In effect, the transatlantic cable was a giant, ambitious, hugely expensive experiment.
21:26The failure of science to keep pace with technology had been exposed.
21:31And a new, more theoretical and, for me, much more exciting approach
21:38to understanding electricity began to unfold.
21:47Armed with this new understanding of how electric pulses actually moved along the cable,
21:54improvements were made to its composition, design and how it was laid.
22:01It would take another eight years of scientists and engineers working together
22:07before a working cable was finally put in place.
22:13And on Friday, 27 July 1866, a message was sent from Ireland to Newfoundland,
22:21clear and crisp.
22:25A treaty of peace has been signed between Austria and Prussia.
22:30At last, the dream of instant transatlantic communication had become a reality.
22:39The success of the 1866 cable makes the world a smaller place, yet again.
22:49The change from a world where it took days or weeks or months for information to travel,
22:56you know, to a world in which information took seconds or minutes to travel,
23:01you know, is far more profound, I think, than anything that's taken place during my lifetime.
23:09The invention of the telegraph changed ordinary people's lives.
23:14But it would be the breakthroughs in how we used continuously flowing electric currents
23:20that would have an even greater impact.
23:25Because inventors were developing a new way of using electricity.
23:34To make something every person in the world would want.
23:40Electric light.
23:46Until the 19th century, we only knew of one way to make our own light.
23:52Burn things.
24:02And by the middle of the 19th century, we'd perfected a very effective way of lighting our homes.
24:08Using gas.
24:14A typical British home in the 1860s would have been lit like this.
24:19Highly flammable gas would have been pumped directly into people's houses through a network of pipes.
24:28But these gas lamps were too dull for large outdoor areas.
24:34So, railway stations and streets began to be lit from a more powerful source.
24:40Electric arc lights.
24:44The first arc lights were demonstrated by Michael Faraday's mentor, Sir Humphry Davy, at the Royal Institution as early as
24:531808.
24:54And they worked by passing a continuous spark of electricity across two carbon rods.
25:04But their intense white glow was just too bright for people's homes.
25:09For an electric light to compete with gas, it would need to be subdivided into many smaller, less powerful and
25:16more gentle lamps.
25:17Whoever succeeded in bringing electric light to every home in the land was guaranteed fame and fortune.
25:26And by the early 1880s, the most famous, most prodigious, most fiercely competitive inventor in the world had taken on
25:35the challenge.
25:36The American Thomas Elver Edison.
25:42For Edison, invention was a passion. It's what he loved doing. He loved being in the laboratory.
25:49The first thing that drove that passion is that it was a lot of fun for Edison.
25:54I think that was the thing that he found most exciting, is that this was something he did well and
26:00it allowed all of his creativity to come to the fore.
26:05Edison is Mr. Electrical Invention.
26:10He's the man they trust. He's the man that they think can do anything.
26:16He's also the man who has his carefully cultivated connections with entrepreneurs, with people who are willing to put their
26:26cash where Edison's mouth is, so to speak, and back him in this sort of venture.
26:31For Edison, the money was probably the least important reason. For Edison, the money was important for one reason, to
26:37allow him to do the next project.
26:42Edison had assembled a group of young and talented engineers at a cutting edge laboratory in New Jersey, 26 miles
26:51from Manhattan.
26:54Edison.
26:54Menlo Park would become the world's first research and development facility, allowing Edison's team to invent on an industrial scale.
27:06They worked incredible hours. You know, one of them talked about how he hardly ever saw his children, because he
27:13was in the lab all the time.
27:20But they knew they were in the midst of something really important, right, that if Edison succeeded, right, if they
27:26succeeded with Edison, that their futures were secure.
27:35Edison's dream was to bring electric light to every home in the land.
27:40And with his team of engineers behind him and the vision of an electric future ahead, he launched his campaign.
27:49The race to bring electric light to the world was to play out in the great cities of the time.
27:55Edison, New York, Paris, London.
28:00Edison's Menlo Park team set about developing a totally different form of electric lamp.
28:07The incandescent light bulb.
28:10In fact, Edison's light bulb design wasn't all that new or unique.
28:16French, Russian, Belgian and British inventors had been perfecting similar bulbs for over 40 years.
28:25And one of them, an Englishman, Joseph Swan, had been developing his own version of an incandescent lamp.
28:33Both Swan and Edison's light bulbs work by passing an electric current through a filament.
28:39Now, a filament is a material in which the electric current flows through with more difficulty than it does through
28:47the copper wire in the rest of the circuit.
28:50And it relies on the idea of resistance.
28:53Now, inside this jar, I have a filament made out of ordinary pencil lead.
28:57And we can see what happens as I pass a current through it.
29:02Down at the atomic scale, the atoms in the filament impede the flow of electricity.
29:08So it takes more energy to force it through.
29:11And this energy is deposited in the filament as heat.
29:15Now, as it heats up, its resistance goes up, which again raises its temperature until it glows white hot.
29:25Now, one of the first materials Edison used for his filaments was platinum.
29:34With its relatively high melting point, platinum could be heated to a white-hot temperature without melting.
29:42It could also be stretched into thin strands.
29:46And the thinner the strand, the more resistance it offered to the current passing through it.
29:52But platinum was expensive and didn't offer enough resistance.
29:59The race was on to find a better alternative.
30:03And the solution came when the Menlo Park team switched to a method Swan was also developing.
30:10Using a vacuum to stop cheaper carbon filaments from burning up too quickly.
30:17Edison and Swan tested all kinds of different materials for their filaments.
30:23Everything from raw silk and parchment to cork.
30:26Edison even tested his engineers' beard hair.
30:31Eventually, he settled on bamboo fibre, while Swan used a treated cotton thread.
30:38Edison and Swan's lightbulb designs were very similar.
30:42Eventually, they came to an agreement and went into partnership to sell lightbulbs in the UK.
30:49Today, many people still believe that Edison alone invented the lightbulb,
30:55while Swan has become a footnote in history.
31:05But his incandescent bulb was only part of Edison's strategy.
31:10He'd also invented an entire electrical system of sockets, cables and meters to go with it.
31:18And being a brilliant businessman, he'd developed a groundbreaking new way of distributing electricity.
31:26Edison knew that the key to making money from his system was to generate the electricity in a central station
31:33and then sell it to as many customers as possible.
31:37It seems obvious to us now, but until then, anyone who wanted to use electricity had to have their own
31:43noisy generator to make it.
31:47Edison's ambition was huge.
31:50Edison's ambition was huge.
31:50He wanted to light the fastest growing and most exciting city in the world.
32:00New York.
32:02In the summer of 1882, Edison stood in a unique position, at the centre of 19th century science and invention.
32:12He'd patented a cutting-edge incandescent lightbulb.
32:16He'd amassed an unprecedented knowledge of electrical engineering.
32:19And above all, he'd cultivated a reputation among the American public of being such a genius inventor that journalists hung
32:28on his every word.
32:29And the financial muscle of Wall Street was quick to throw itself behind his new ideas.
32:35His vision to electrify Manhattan, and then of course the rest of the world, was seemingly within his grasp.
32:48Because Edison and his team were about to launch their most expensive and risky project yet.
32:55America's first power station generating continuous direct current.
33:04Just before 3pm on the 4th of September 1882,
33:08Thomas Edison, surrounded by a gaggle of bankers, dignitaries and reporters,
33:14entered J.P. Morgan's building right behind me,
33:17flicked one of the Edison patented switches,
33:20and 100 of his incandescent bulbs began to glow.
33:26Turning to a nearby journalist, he said,
33:28I have accomplished all that I've promised.
33:34Half a mile away on Pearl Street,
33:37Edison's new power station, costing half a million dollars and four years of hard work,
33:44had sprung into life.
33:46The current surged through buried cables, stretching out in each direction.
33:53Of course, it might seem obvious to us now, but in New York back in the early 1880s,
33:59the idea of burying electric cables underground seemed like an unnecessary expense.
34:04This street would have been criss-crossed with hundreds of cables,
34:09used for telegraphs, telephones and arc street lighting.
34:13Looking up, you'd have seen a tangled mass of black spaghetti blocking out the light.
34:20Edison knew this dangerous situation had to change.
34:24And for him to make as much money as he could, electricity needed rebranding.
34:30It had to be considered safe.
34:33So Edison is arguing both for the greater safety of his DC low voltage system and for underground lines.
34:42He can argue that he has a much safer system than electric arc light for streets,
34:49or gas lighting for indoor lighting, right?
34:52He doesn't have to worry about fires, doesn't have to worry about electrocution,
34:55that all of this is much safer because of the system he's created with this underground system.
35:03Burying every cable was not only very expensive, but was a logistical nightmare,
35:08because this was one of the busiest square miles in the world.
35:12Edison chose this area for a reason.
35:16Wall Street.
35:18Rich, important, influential.
35:21Because for Edison's system to make money,
35:23all these wealthy customers had to be within a mile of his power station.
35:32And this was because Edison calculated the thickest cable he could afford
35:37would only carry an adequate amount of his continuous direct current to customers within this range.
35:46This was a huge leap forward,
35:49because for the first time, dozens of customers could be supplied by just one power station.
35:56But there was a big problem.
35:58Edison's network could never be economical in lighting America's new suburbs.
36:03They just didn't have the concentration of customers needed to make building these expensive power stations worthwhile.
36:12Had we stuck with Edison's way of generating and distributing electricity,
36:17the world would be a very different place.
36:21We'd have to have power stations scattered around no more than a mile apart,
36:27even in the centres of our towns and cities.
36:29And it would be extraordinarily expensive to even provide power for smaller communities.
36:39But someone who held the answers to these problems was about to enter the story.
36:45Someone who would help create the modern world,
36:49and who'd play an integral part in one of the biggest fallouts in scientific history.
36:54His name was Nikola Tesla, and he was right under Edison's nose.
37:07Nikola Tesla was a Serbian inventor, who was born in Croatia,
37:12and who worked for Edison briefly after arriving in New York at the age of 28.
37:19European, introverted, a deep thinker.
37:22He was everything Edison wasn't.
37:26Edison and Tesla could not be more different in the way that they handled their self-appearance and their manners,
37:32and the way that they constructed a public image for themselves.
37:35Edison could care less about the clothes that he had on,
37:38and if he spilled chemicals on his good Sunday suit,
37:41then he spilled chemicals on his good Sunday suit.
37:43He was, you know, basically a very, very kind of slovenly guy.
37:48Tesla, on the other hand, even as a young man in his mid-twenties,
37:52is thinking about his appearance, how he comes across to people,
37:56so he cares about his clothes, he cares about his manner.
37:59Indeed, he even cares about how his photograph, his portraits are taken,
38:03and he always wants to make sure that he has a nice three-quarter profile,
38:06so you don't see the fact that he has a bit of a pointy chin.
38:12The life and death of Nikola Tesla is one of the most fascinating yet tragic stories
38:19of scientific brilliance, cutthroat business and shocking public relations stunts.
38:28The American public may have been wowed by Edison's new direct current power stations,
38:34but Tesla was less impressed.
38:38He had a dream electricity could be transmitted across entire cities or even nations,
38:44and he believed he knew how it could be done,
38:48by using a different type of electric current.
38:52the along the other hand.
38:58Electrical experts knew that the smaller the current sent down a cable,
39:03the smaller the losses in it through resistance,
39:06and so the longer the cable could be.
39:08Tesla proposed using a method of transmitting electricity
39:13where the current could be lowered without a fall in the amount of electrical power at the other end.
39:19It was called alternating current.
39:24Alternating current is exactly that.
39:27It's an electric current that alternates between moving in one direction,
39:32then the opposite direction very quickly,
39:35as opposed to a direct current which moves only in one direction.
39:40Tesla was interested in alternating current
39:43because, like other electrical engineers in the late 1880s,
39:47he realised that as you raise the voltage of any current that you transmit from point A to point B,
39:54it's going to be more efficient to have a higher voltage.
39:59And since the amount of electric power in a cable
40:02is its voltage multiplied by its current,
40:05increasing the voltage meant the current in the cables could be reduced,
40:10and so losses due to resistance would be less.
40:14However, you don't want very high voltages on the order of, say, 20,000 volts coming into your home.
40:21So you need to step down the current that is being transmitted over a distance into your home,
40:26and to do that you need a converter or a transformer.
40:30Alternating current allows you to use a transformer
40:33to make that switch from the high transmission voltage
40:36to the lower voltage that you're going to use at consumption.
40:43Perfecting the technology to transmit electricity hundreds of miles from where it was generated
40:49would mark a huge step towards the modern world.
40:54And a wealthy industrial entrepreneur was already developing the solution.
41:00His name was George Westinghouse.
41:04Westinghouse believed alternating current was the future, but it had a big drawback.
41:10While it was fine for electric light, unlike direct current, there was no practical motor that could run on it,
41:18and no-one believed there ever would be, apart from Nikola Tesla.
41:24Tesla, as an inventor, liked to say that the first thing you need to do is not to build something,
41:30but to imagine it, to think it through, to plan it.
41:35And he had what modern-day psychologists would call an eidetic memory.
41:39He could basically remember everything that he saw and then visualise it in three dimensions,
41:45and they often say that the people that have this skill see it about an arm's length away out here,
41:51and they see it in three dimensions in that space.
41:53And all of the indications are that Tesla had that ability.
42:01This is a Tesla egg.
42:06It's a replica of the one Tesla used to demonstrate his greatest breakthrough,
42:11and one of the most important inventions of all time.
42:15It showed how rotary movements can be produced directly from an alternating current,
42:22crucially, one that could be generated thousands of miles away.
42:25This was something that had never been done before.
42:38When Tesla was working on the alternating current motor,
42:41he was thinking big, and he was not just tinkering with one little component of the motor
42:47and saying, gee, if I can make that a little bit better, it will work out.
42:51He's actually thinking about an entire system that involves the generator,
42:55the wires to the motor, and the motor itself.
42:59He's a complete maverick. He's thinking outside the box.
43:02He's doing things very differently than any of his fellow contemporary inventors.
43:07Tesla's solution was ingenious.
43:09He fed more than one alternating current into his motor
43:13and timed them so that they followed in sequence with each other.
43:18The first alternating current energised a coil of wire inside the motor,
43:24creating an electromagnetic field
43:26which attracted the motor's central moving part to it and then faded.
43:31The second overlapping current fed the next coil,
43:36dragging the moving part around further before it faded,
43:40and the same for the third coil and the fourth.
43:43The result was a revolving magnetic field
43:47strong enough to make the motor, or in this case his egg, spin.
43:52Tesla designed an entire electrical system around this
43:56called polyphase transmission.
43:58This meant a noisy and smelly power station,
44:02generating lots of useful alternating current,
44:05could now be situated away from populated areas.
44:10And for the first time you can build large power stations
44:13wherever you want, on the edge of town, or at a waterfall like Niagara,
44:17and you can then distribute the power over long distances
44:20and serve all the people in a major city or metropolitan centre.
44:26Tesla's breakthrough was the last piece of the jigsaw,
44:30but he still had to convince the world that his solution
44:34was better than the direct current method championed by Edison.
44:44Edison continued to roll out his direct current system,
44:48building power stations across New York State.
44:54But then Tesla met George Westinghouse,
44:58the man who could make his dreams into a reality.
45:03In July 1888, Westinghouse made an offer for Tesla's patents,
45:10which has become part of the mystery and folklore
45:13surrounding the whole Nikola Tesla story,
45:16where it's difficult to separate fact from fiction.
45:21Tesla was paid $75,000 for his alternating current patents,
45:27and offered $2.50 for every horsepower his motors would generate.
45:32This should have guaranteed him vast wealth for the rest of his life.
45:36But that isn't what happened.
45:42It's clear to us now that at the time the AC system
45:45was a much better method of transmitting electric power.
45:49And you'd think that with Tesla's breakthroughs,
45:52nothing could stand in the way of the success of AC over DC.
45:56But one man still believed totally in his direct current inventions.
46:02From the filaments of the bulbs to the switches, sockets and generators.
46:07And he wasn't about to waste millions of dollars on changing them.
46:14Edison.
46:16The battle lines were drawn.
46:19Westinghouse and Tesla went toe-to-toe with Edison
46:23for New York's lucrative lighting contracts.
46:26Two completely different systems battling it out for one ultimate prize.
46:32The chance to light up America and then the world.
46:37It would become known as the War of the Currents.
46:45Both camps tried to undercut each other on cost,
46:48but Edison believed his beloved direct current
46:51was better than alternating current because it was safer.
46:58Touching an Edison cable with its low voltage was painful but relatively harmless.
47:04Whereas alternating current cables carried a much higher voltage
47:09and touching them could be deadly.
47:13So, what Edison was trying to do was to again define his DC system, right, as the safe system.
47:22It's better than electric street arc lights.
47:26It's better than gas.
47:28And it's now better than high voltage AC incandescent lighting, right?
47:32It's the system that's safe.
47:34You adopt the Edison system, you can be sure it's going to be safe.
47:40Edison claimed that AC was a more dangerous type of current than DC.
47:46And he highlighted every accident to Westinghouse's workmen
47:50and every fire caused by short circuits.
47:58It was a potent message because in the 1880s many people were still terrified by electricity.
48:06It could shock and even kill in an instant and the reasons why still weren't fully understood.
48:13For many, the idea of piping this invisible killer into their homes was utterly ludicrous.
48:22So, the weapon used in the War of the Currents was fear.
48:31And a little-known electrical engineer, Harold P. Brown,
48:36was about to take the fight against AC to a whole new level.
48:44It was to prove one of the most extreme and negative publicity campaigns in history.
48:51Brown had devised a unique and theatrical way of demonstrating the deadly power of AC.
49:00And he was eager to share it with the world.
49:04So, on a warm summer's evening in July 1888,
49:09he gathered together 75 of the country's top electrical engineers and reporters
49:16to witness a spectacle they would never forget.
49:24Brown's plan was extremely macabre.
49:27He'd paid a team of street urchins to collect together stray dogs roaming Manhattan.
49:33Out on stage, he addressed his audience.
49:37I have asked you here, gentlemen,
49:39to witness the experimental application of electricity to a number of brutes.
49:47his demonstration involved electrocuting the dogs with DC and AC power
49:56in an attempt to show that AC current killed them more quickly.
50:01And it wasn't just dogs.
50:04Brown went on to make public spectacles of killing a calf and even a horse.
50:11And he moved from dogs to larger animals for a reason.
50:14He wanted to show that the AC form of electricity was so dangerous
50:19it could kill any large mammal, including humans.
50:33Brown's animal experiments had persuaded American politicians
50:37the most humane method of executing condemned criminals
50:41should be with alternating current generated by Westinghouse machines.
50:48Edison's lawyers even suggested a new term to describe being electrocuted in this way.
50:55To be Westinghoused.
50:59And at precisely 6.32, on the morning of the 6th of August 1890,
51:06a 45-year-old man, William Kemmler, was strapped to a wooden chair
51:11and two soaking wet electrodes were carefully attached to him.
51:16And as 26 officials and doctors looked on from an adjoining room,
51:21Kemmler said goodbye to the prison chaplain and waited.
51:30The execution of William Kemmler marked the lowest point in the war of the current.
51:36But it wouldn't quite mark the end.
51:39Because Nikola Tesla was about to do something that had never been seen before.
51:43something so wondrous and daring that it would live on forever in the memories of those who saw it.
52:13Tesla had been developing a method of generating very high-frequency alternating currents.
52:20And on May 21st, 1891, at a meeting of top electrical engineers, he demonstrated it.
52:33In an almost magical display of awesome power and wonder,
52:38and without wearing any safety chain mail or mask,
52:42tens of thousands of bolts produced by a Tesla coil passed across his body
52:47and through the end of a lamp that he was holding.
52:56Tesla's alternating current was at such a high frequency that it passed through his body
53:02without causing serious harm or even pain.
53:06His demonstrations showed that if handled correctly,
53:11alternating currents at extremely high voltages could be safe.
53:16The war of the currents had been won by Westinghouse and Tesla.
53:22In 1896, a new power station was completed at Niagara Falls
53:27using Westinghouse AC generators to produce Tesla's polyphase current.
53:34Finally, huge amounts of power could be transmitted from the falls to nearby Buffalo.
53:40And then, a few years later, the Niagara plant was providing power to New York City itself.
53:48And today, almost all of the electricity generated in the world
53:53is done so using Tesla's system.
54:03But Tesla's story doesn't end in fame and fortune.
54:10Although he went on to make significant contributions to many other areas of science and invention,
54:16to save George Westinghouse from ruin after a stock market crash,
54:21he gave up his claim to the royalties from his polyphase inventions.
54:29Nikola Tesla was a uniquely talented man, and we owe him so much.
54:34But he was also hugely complicated.
54:37And sadly, later in life, he became more and more troubled.
54:40He was fixated with the number three, counting it out loud as he walked.
54:45And he developed strange phobias with germs and with women wearing pearl jewelry.
54:52In many ways, his brilliant mind simply spun out of control.
55:01As Tesla's life unraveled, he withdrew from people and found emotional comfort elsewhere.
55:08He became obsessed with pigeons and was regularly seen feeding them here in Bryant Park in the centre of Manhattan.
55:16He even fell in love with one particularly unusual white bird.
55:20And when it died, he was left heartbroken.
55:35As an old man, Tesla was left almost bankrupt and alone, living as a semi-recluse in this hotel.
55:51His last years were spent here in room 3327 of the New Yorker Hotel.
55:57Sad, confused, destitute.
56:06Edison went on to become an American hero.
56:10And his company would form part of General Electric.
56:15Even today, one of the world's biggest multinational corporations.
56:21In January 1943, the story of Nikola Tesla was coming to an end.
56:29But looking out across the Manhattan skyline for the very last time,
56:34he saw a sky lit up with twinkling lights
56:38and a million lives transformed by his genius.
56:58The ability to generate and transmit electricity
57:02and the invention of machines to use it
57:04have changed our world in ways we couldn't possibly have imagined.
57:11We can now generate billions of watts of electricity every second,
57:17every hour, every day.
57:20And whether we do it using coal, gas or nuclear fission.
57:24Power stations all rely on the principles discovered and developed by Michael Faraday,
57:32Nikola Tesla and all the other early electrical engineers from an amazing age of invention.
57:40We now take electricity for granted and have forgotten how magical and mysterious a force it once was.
57:48But there's something we should never forget.
57:51Today, without it, the modern world would collapse around us
57:56and our lives would be very, very different.
58:06In the next episode, we tell of the electrical revelations
58:09that led to a revolution in our understanding of this amazing force.
58:19To find out more about the story of electricity
58:22and to put your power knowledge to the test,
58:25try the Open University's interactive energy game.
58:29Go to bbc.co.uk forward slash electricity
58:34and follow links to the Open University.
58:41And the story of electricity concludes here on BBC HD at the same time next Thursday.
58:47Next this evening, Tracey Emin on Who Do You Think You Are?
58:51you
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