Original subtitles

The world at night seen from outer space.

Millions of lights glitter across the surface of the globe.

And in these twinkling lights is the story of how light created the modern world.

About 150 years ago, light stopped living in

heaven and started living in the material world.

It became a kind of good you could buy and sell. It was artificial.

And mastering artificial light has unlocked the secret of light itself, a secret so

extraordinary that it would revolutionize

our understanding of the way the world works.

But it's come at a price that we are still learning to live with.

In 1847, a 16 year old Edinburgh schoolboy was taken to see

one of the minor scientific wonders of the Victorian world.

It was this, a prism made from a special crystal found in Iceland and

what it did was something completely surprising to scientists at the time.

It played tricks with light. It is transparent, it lets

the light through. Nothing puzzling there, but wait.

two of these crystals, combined, make the light go out. They extinguish the light.

Light seemed to be violating all the known laws of nature.

Now the Scottish schoolboy was called James Clerk Maxwell.

And his fascination with what the strange crystals did to light set him on a

journey that would unravel the mysterious and astonishing nature of light itself.

Maxwell lived at a time when Britain was the workshop of the world.

Its traders, merchants, and engineers dominated the globe.

They understood how heat, pressure, and sound worked.

Its architect could build the most extraordinary structures, they

could bring light into the interior of the very buildings themselves.

Yet, light itself baffled them.

Maxwell was captivated by mysteries like this.

Young Maxwell liked playing with things, he wanted to know their

particular goal, it was a phrase that was never out of his mouth.

He would look at bells and locks and keys, and how

water flowed, and the strange properties of light.

and so he set about making his own optical instruments to

explore the peculiar properties of the Iceland crystals.

What we now know as polarizing lenses.

It is based on very simple idea. The light falls onto this mirror here and

then along the tube, and you can look it through a second mirror at the end.

Now Maxwell wasn't that concerned with the fact that

polarization allows light through or else it stops it.

That wasn't the primary concern for him. No. What he wanted to do was

to use this device to see things you couldn't see with the naked eye.

He started with a seemingly unremarkable piece of glass.

Maxwell would heat it unit it was red hot, far too hot to touch,

and then plunge it into ice cold water that it would suddenly set.

There will be lines of tension inside the glass, we can't

see them, but when Maxwell put them into his instrument,

and then looked through the mirrors, what he saw were the most amazing patterns.

These are frozen stress lines, things you just can't see with the naked eye.

But with Maxwell's instrument, this crucial lines

of frozen stress become visible and beautiful.

How could brute physical forces affect something as intangible as light?

And we know just how fascinated he was, because we've got here the watercolors

that he did himself when young, of the colors he could see through his instruments.

These colors were speaking to Maxwell.

cause what they suggested was that there must be some kind of relationship between

the forces acting inside some stuff like glass and the way light traveled through it,

and that was really odd. What could be the relationship between pressure

and tension, and the way light traveled, and the colors that it showed.

Light was posing a series of problems for people,

they just didn't seem to be smart enough to solve.

Only a couple of years before the young Maxwell

had started working with those polarizing prisms,

light had posed a really big challenge that was very hard to

understand. It was this experiment here, again he used Nicol prisms.

Between the prisms, you put a piece of very heavy glass, and you shine lights through

the prisms and the glass. What you do now is put a very strong electromagnet near it.

And when you turn the magnet on, the light changes.

Now this was a very, very peculiar phenomenon. How could magnets affect light?

And there were yet other mysteries to do with light.

When it was well known that light heats thing up a bit, but it turned out that stuff

would get really warm through some kind of

radiation even where you couldn't see any light.

What was the curious relationship between light and heat?

And light sensitive paper would turn black,

even though there was no visible light around.

It was as though there was much more to light than met the eye. Light was

the trickster, it was the central problem for physicists to understand.

The riddles set by light became a standing

provocation to the confidence of Victorian scientists.

If they could solve what light was, they could pull

together chemistry and mechanics, electricity and magnetism.

Solving the problems of light would put them on the

path to the first, adequate, unified theory of the world.

It became one of the hottest topics in Victorian science.

So when Maxwell went to Cambridge university, light was

almost inevitably one of his main areas of his study.

Maxwell has come down to us as an odd character,

he pondered the math of why cats always fall on

their feet. And why paper fell in particular patterns.

Could there be some kind of law behind them that would enable

him to draw up universal rules for how the world worked.

He even tried his hand on poetry, though, as

history will probably judge, with much less success.

When the telegraph cable under the Atlantic failed to work, Maxwell wrote an ode.

Under the see, no little signals are coming to

me. Under the sea, something has surely gone wrong.

And its broke, broke, broke, what is the cause of it doesn't

transpire, but something has broken the telegraph wire.

Yet behind the amateur versifier was a brilliant analytical mind, which was to fuse

two traditions, which until now had never seen eye to eye: math and engineering.

Down here in the university of Cambridge of bastion of the church of England,

it was as though the industrial revolution had never happened, not only that,

but there were whole sciences that really mattered

to engineering like the science of heat, the steam

engines, or electricity and magnetism. They were

simply banned from the undergraduate curriculum.

Because they were too radical, they were too new

for the sensitive palates of Cambridge undergraduate.

So when Maxwell arrived here, he knew what he was in for, he brought

his own equipment with him, his own prisms and lenses and polarimeters

In family letters, he called them his dirt as

though he really understood the way in which

Cambridge dons might think about what engineering

meant in a bastion of theology and mathematics.

The clash of these two traditions would enable

Maxwell to explore light in a totally new way.

Yet surprisingly, the biggest revelation about light would

come from another problem that fascinated Victorian society,

the relation between electricity and magnetism.

In 1831, Michael Faraday had demonstrated that if you wave a magnet

near a coil of copper wire, it would produce an electric current.

What nobody could explain was why.

Maxwell set about looking for a mathematical explanation.

He had to invent a new mathematical language.

And what this gave him, after huge amount of work, were four stunning equations that

showed for the first time the precise

relationship between electricity and magnetism.

But there was more, because hidden in them was something else: the truth about light.

The particular excitement about this set of equations

is that they start off by describing the phenomena

not of light, but of electricity and magnetism.

If you represent the way in which electrical and

magnetic forces interacts with these 4 equations,

you start to see, as Maxwell gradually realized with extraordinary excitement

that light, electricity, and magnetism have something to do with each other,

but then there is more, an extraordinary sudden moment of realization

that this number, which appears in the equations, describes

the speed, with which waves travel in electromagnetic space,

and it turns out, Maxwell was astonished, it turns out that speed

with which these waves moved is exactly the same as the speed of light.

There could only be one explanation.

Light, electricity, and magnetism must be the same kind of thing.

Light is an electromagnetic wave.

It is one of the biggest insights into how the world works in the history of science.

Most of his contemporaries found it impossible to grasp.

People stumbled along behind him in his wake,

either not understanding his lectures, or simply not being able

to follow the leaps of imagination which Maxwell engaged in.

When he was a student, and when he was a professor, what his colleagues used to

say about him was that, Maxwell is always right, but you can't always see why.

That Maxwell never made a mistake, but it was impossible to check exactly how

he got from where he started to the startling ideas with which he ended up.

Yet for Maxwell, the world now fitted together beautifully.

If light is an electromagnetic wave, then the different colors of

the spectrum correspond to waves vibrating in different frequencies.

There is red at one end, this is the light that is vibrating pretty slowly.

And then as the speed of vibration increases,

we see the colors from red to orange, all the way up to

blue and violet. Violet light vibrating extremely fast.

Other mysteries also fell into place like the

apparent presence of light even when it can't be seen.

Beyond the edges of what we can see, beyond the visible spectrum,

there are something very spooky indeed. There is

invisible light. There is radiation we can't see.

Faster than blue, faster than violet, there is ultraviolet light.

It was this form of invisible light that was mysteriously fogging photographic paper.

At the other end, vibrating slower than the red is infrared, heat radiation.

This is the mysterious source of heat that scientists had found associated with light.

The spectrum gets wider and wider,

the very neatness of the whole edifice gave Maxwell enormous satisfaction.

One of the things that Maxwell thought was that there is a really deep

relationship between the beauty of mathematics and the reality of his science.

If something is true, Maxwell reckoned, you

must be able to express it in an aesthetic form,

and that is what the equations are doing for him.

They summarize this idea that there is a profound relationship between the way

the world works and our understanding that the way the world works is beautiful.

In the years to come, these 4 equations would have enormous impact.

They would influence every new technological development for ever after.

The relation between light and civilization has always been pretty important,

but after Maxwell's equations, nothing was ever gonna be the same again.

He was gonna bring light into dark corners, and his tools and

techniques would going to completely change the history of the world.

Society was about to change forever,

but not necessarily for the better.

Maxwell's equations arrived at a time when

Victorian Britain was hungry for new forms of light.

Gas was hot, smelly, and occasionally dangerous.

Now there was a serious alternative.

Maxwell's equations unlocked the potentiality of electromagnetism.

What could now happen was that people could master magnets

to generate a constant and reliable electrical supply.

And that electrical supply at last made electric lighting viable.

It is a really good example of the way in which something that

might seem abstract and out of this world is brought down to earth.

Intelligent and inventive men would be able to

exploit the potential and make lots of money.

One of these men was a chemist, working in the north of England.

Newcastle was a boom city of the 19th century.

It was full of entrepreneurs and businessman

with an eye on the main chance and the learning

and skill to follow any business opportunity.

One of them was a local manufacturing chemist, Joseph Swan.

A gentleman of letters, but with the keen eye to spot

any commercial opportunity that would come his way.

Victorian engineers were already experimenting with

primitive ways of using electricity to make light.

Electric light pulled in enormous number of people's

interests, it drew on state of the art engineering,

but the problem was that the current form of electric light in use, arc lighting,

just wasn't cut it. It didn't really work. It was unstable, it was noisy, it burst.

There had to be a better way of bringing

illumination into the home and into the factory.

Swan set about finding a solution.

One alternative to lighting by electric sparks would be to use the fact that

some substance is glowed, they incandesce when you pass electricity through them.

The problem with that kind of electric glow is that anything

that glows so brightly is likely to burn and disappear.

The solution would be to get it to glow in a vacuum

where there is no air, so combustion couldn't happen.

And this turned out to be crucial for the development of electric

light. It was like a really successful convergence of technologies,

at just the moment when electric generators were reliable enough

to produce the electric inputs for these lights, at the same time,

big vacuum pumps came on the stream, that could suck all the

air out of bulbs and maintain really, really low air pressure.

With this convergence of technologies, it became possible to

think of having a light bulb with a glowing filament in a vacuum.

But what should the filament be made of?

Now Swan knew that carbon, when it is heated up, could be made to

glow very brightly, but what kind of substance shall he carbonize?

He looked at paper, he looked at a range of substances, but

then one day, he decided to try carbonizing this: cotton.

So he would pack the cotton into this container of charcoal. And seal it

and put it into an almost airtight container, in the oven, and bake her.

After he baked it, he got this, the first viable filament for electric light.

With this carbonized cotton filament, he was able to make electric

light bulbs like this, shaped like a lemon, and glowing bright red.

Swan's new bulb was a technological triumph.

Joseph Swan's new incandescent electric light was an instant heat with

the posh and the wealthy amongst Victorian Britain's industrial class.

Now, one of Swan's best and closest friends was sir William Armstrong, Mr. Tainsign.

Armstrong was an enormously wealthy and ambitious Victorian entrepreneur. And Swans'

new invention was just the sort of thing he needed to impress his wealthy customers,

they be brought to Newcastle on Armstrong's

boats, they be greeted by Armstrong's employees,

they would be taken up to Armstrong's country

residents on one of his own private railway trains.

Steaming up the hill through the dark forests,

And what they found when they arrived was this: Cragside.

Cragside was really Armstrong's pride and joy. He turned it

into a kind of showcase for state of the art modern technology.

It was described in the newspapers as the palace of a modern magician.

This house became an electrified palace.

It was the very first house to be lit by the

new fangled incandescent electric light bulbs.

More than 40 of them delivering the

illumination of more than a thousand candles.

Here is a wonderful example. This is an incandescent electric light bulb, pretending

to be a gas lamp, pretending to be a candle, pretending to be a medieval heraldic line.

It is a perfect image of the way in which Armstrong and Swan's new electric

technology brilliantly adapt itself to the

aristocratic values of the late 19th century.

Yet there was a major flaw in Swan's plan to use

Cragside to encourage others to buy light bulbs.

To keep his house in electric, William Armstrong

had one very big advantage. He had this.

He had his own river

which he used to run a big hydroelectric scheme to supply

the electric power that kept Cragside lit with electric light.

Now if Joseph Swan's scheme was going to have any future at all, he couldn't possibly

rely on people like William Armstrong with their own private electrical supply.

What was needed was a public supply of electricity.

In the closing decades of the 19th century, there

was really only one place that was going to happen.

Swan had lit a house. 3000 miles away in New

Jersey, was a man who wanted to light the world.

Thomas Alva Edison had also just invented the incandescent

light bulb, but the parallel with Swan stops right there.

Edison was in every way larger than life. He was a kind of modern hero that no one had

ever seen before, a mixture of engineering entrepreneur, businessman, and visionary.

In 1878, Edison set about building the world's first public electricity supply.

He had to invent every single component from the insulation surrounding the cables,

to the meters, fuses, switches, and above all, the light fittings that made it work.

But that was just the beginning. Making electric light

available is one thing, making it economic is quite another.

The Edison revolution had only just begun.

Perhaps the most important problem that the Edison

system faced was that you only need to turn the lights on

at the night, that meant the electric light was only

gonna be used for a very limited part of each 24 hours.

Now you can't easily store electric power,

and it is really inefficient and costly only to run an

electric system for a very limited period of the night.

The answer was to persuade a skeptical public

to buy more and more devices which run on

electricity that would make sure that they were

customers of the electric companies on a 24/7 basis.

Edison's revolutionary insight was that to sell

electricity, he needed to sell a life style.

I want to tell you a bit about the electric cooker.

So clean, so reliable and so labor saving.

Well, I never.

Come on now, get us to sign up for the thing Think of the husband's

little costume far less than all those of the doctor��s bill of indigestion

it is not salesmanship, it is just kindness to animals.

No stone was left unturned to convince a skeptical

public that electric lighting was the new future.

One electric light promoter, a man called William Priest, went to bizarre length.

In my house, I use lamps that required 30 volts

I often put the wires into the mouth of my little children.

They don't much like it, but it doesn't harm them

Well, I never. Well I never. Is so that clean ever?

Edison's campaign to market electricity and the electric light

bulb really set the tone for consumer marketing ever since.

Because what Edison realized was that he wasn't so much selling light

bulbs, he was selling dreams, dreams of light, of leisure, of less work.

People were buying Edison's light bulbs not so much because they needed

them, but because they had that dream, that vision of a world of light.

And that technique that Edison started with his sales campaigns

for electric light bulbs has dominated marketing ever since.

It is been kept going, whether you are selling

cars, or whether you are marketing computers.

Today, light bulbs are everywhere.

They have become the symbol of a modern, thrusting, 24 hour 7 day a week, society.

It is a world which has harnessed the genius of Maxwell, with the brilliance

of Edison, to give us more control over our environment than ever before,

or has it?

For many, it is an encouraged world in which most

people may in reality have less control than before.

Why is it exactly that we live in a 24/7 society?

Is it because we really want to?

or is it, rather, because it is the dictates of the machines

that they become profitable if they are switched on all the time.

Is it that we live in a world because we have chosen to live

in a world that is lit every single day and every single night?

Or is it not rather the demand for profit and

engineering that keeps the world going, just as it does?

So, it looks as though these technologies of artificial

light gave us unprecedented control over the world around us,

but maybe, just maybe,

we are the victims, we are under the control of machines and the market.

Yet for scientists, the real impact of the light bulb had

nothing to do with control, in fact, it has been very opposite

The light bulb was going to blow apart the laws of physics and reveal the world that

is more uncertain, more unpredictable, and more dangerous than its inventors dreamt of.

In the mid 1890's, in the town of Wolfsburg, a German scientist

had embarked on a series of new experiments with light,

his name was Wilhelm Rontgen,

and what interested Rontgen was a new piece of

equipment recently developed from the light bulb.

It was a vacuum tube, a long glass tube from

which almost all the air have been pumped out.

You couldn't make one of these without the

technology which was being used to make light bulbs.

The most extraordinary thing about this was that if you pass an electric

current through the vacuum tube, it started to glow, it started to glow brightly.

The tube was empty, yet something was glowing.

It became known as a cathode ray.

Rontgen was intrigued, but as he played around with

it, he came across something even more extraordinary.

When he increased the charge, and took a photograph of

a hand, he could suddenly see the bones through the skin.

They became known as X-rays.

These X-rays made a sensation, you could see through flash, cloth,

you could see embarrassing things, perhaps, under people's clothing.

Anti X-ray devices was sold,

Lead pants to prevent your privates becoming visible under this new kind of light.

There were cartoons about X-rays, there were X-ray shops,

there was even the idea that X-rays was some kind of spooky ray that came from your

eye, through objects, so that you could

penetrate them in some kind of inexplicable way.

They were the news media sensation of the 1890's

These mysterious rays of light seemed to confirm for many people that

there was something beyond the natural world, a super natural world.

cathode rays, X-rays, all sorts of weird and strange radiations

went along with an explosion of interest in spiritualism,

in fact, I think spiritualism made more sense

in a world where there were kinds of light,

and kinds of rays that you couldn't see, but

showed you things that were otherwise invisible.

After all, how do you communicate with the dead,

by some kind of ray which passes a barrier, which

otherwise seems impermeable. Well, that is what X-rays do.

X-rays travel through glass and flesh and they show

you things that otherwise no human could ever see

In the decades to come, as scientists pieced together what was really going

on, it became clear that X-rays have nothing to do with the supernatural.

They are merely another part of the electromagnetic spectrum.

At the top of that spectrum, vibrating quite fast is blue and

violet light, and beyond it the light we can't see, ultraviolet.

And now a form of radiation emerges that is very high

frequency indeed, vibrating extremely fast: X-radiation.

But the visible glow in the vacuum tube would

lead scientists somewhere very different, it

wouldn't help them communicate with the dead, but

in its own way, it would be just as revolutionary.

One of the centers of research into the strange

characteristic of vacuum tubes was Cambridge.

Here Maxwell's research lab was now run by a physicist called J J Thomson.

It is one of Thomson's misfortunes to have gone down in

history for an incident that is almost absurd in its triviality.

In the 1920s, he is reputed to have shouted at a couple of undergraduates

training for the 1924 Olympics in the great court of the Trinity College.

One of them went on to win gold.

But Thomson, like Maxwell, was a brilliant scientist and in the closing decades of 19th

century, he designed his own cathode ray tube

to investigate this very peculiar form of light.

This is a replica of what Thomson designed.

What is special about it, is that it allowed the cathode rays

to be effected simultaneously by electric and magnetic forces.

And the experiment that JJ Thomson did with this

tube would have the most dramatic consequences.

Thomson was not a practical man, in fact, he was notoriously clumsy.

Yet using his new tube, he performed a series of hugely important experiments.

He would turn the cathode ray tube on,

You'd see, a glow, and a bright point at the other end of the tube,

turn the electromagnets on, the position of the dot moves.

The magnets are deflecting the cathode rays.

Thomson repeated the experiment time and time

again and measure the size of the deflection.

Whatever was coming down the tube was clearly not a wave,

it only made sense if it was a stream of particles.

Thomson then plugged the figures into Maxwell's famous equations,

and the result he got was absolutely dramatic,

he found that the particles making up cathode rays are tiny, much,

much smaller than atoms, and that was an earth shattering result.

Nobody had ever produced any evidence that

there was anything smaller than an atom before,

Indeed, some scientist didn't even believe in atoms.

Years later, Thomson was to describe his findings in a

lecture to the prestigious institute of electrical engineers

Today we know this tiny particles as electrons,

This was really revolutionary stuff,

and what is so exciting about it was that the technology to begin to pull atoms apart,

to begin to tell us story of the most fundamental building blocks of the world,

came straight from light technology, vacuum pumps, light bulbs, vacuum tubes,

It was by thinking about those bits of

machinery that the atom began to be torn apart.

Yet it is one the history's great ironies that at the time nobody realized science was

on the verge of a breakthrough, that will turn physics and the world on their heads.

By the end of the 19th century, most scientists in Europe and

overseas reckoned that in many ways the task of physics was over,

the basic problems have been solved, we knew how light, electricity,

and magnetism worked, we understood the problem of heat and engineering.

Physics turned into a search, not for great

new theories, but just for better measurements.

One of these measurements concern the production of light bulbs,

by now a hugely important and influential commercial activity.

The light and power system was the most important

financial area of European world industry.

Getting the right answer to problems of electric

light and electric power meant big bucks worldwide.

The problem the industry faced seemed scientifically trivial.

What they wanted was to get the maximum amount of light out

of a bulb for the minimum amount of electric energy going in.

so the physicists were asked do some sum and calculate what the relationship

is between the amount of electric energy heating up a piece of metal wire,

and the amount of light coming out when that wire starts to radiate.

No one thought that this was gonna be a deeply important theoretical problem, it

mattered to people's bank balances, it didn't

seem to matter to physical theory very much.

The man the industry turned to was a German physicist called Max Planck

Planck looked at Maxwell's celebrated equations, which

described the relationship between light and energy.

It was then, that he had a shock.

What these equations suggested was that the more energy you put in, and

the hotter the system got, the more light and heat it should radiate.

Maxwell's equations have predicted that the energy level will continue to build up

infinitely until an object was radiating a catastrophic amount of light and heat.

And it would atomize.

But this simply isn't true.

Think about what happens, for example, when

you have a metal bar just resting on the fire,

as it starts to get hotter, it begins to glow, initially just red, then all the

other frequencies begin to kick in, so it goes from red through blue to white heat.

But no matter how hot it gets, it is never going to explode.

This was a prediction from Maxwell's theory that completely fail.

The apparently infallible Maxwell had made a mistake,

It was a body blow to physics.

As Planck tried to untangle what was going on here,

he came up with an idea that was completely counter

intuitive. Now because Maxwell though light was a wave,

Maxwell reckoned that when bodies got hotter and hotter, there was

absolutely no reason why they shouldn't emit more and more light.

Planck then came up with a really cunning

scheme to trying make the theory fit the data.

Planck's problem was similar to the one Thomson had faced.

Thomson had to decide whether cathode rays were waves or particles.

Planck faced an identical dilemma and came up with an extraordinary solution.

What Max Planck was saying, and for him, it was

a quit to any core fix, was that sometimes light

seemed to be behaving like a wave, but sometimes

it seemed to be behaving a bit like a particle.

now after a bit, it quickly emerges, that is a really revolutionary

idea, it completely undermines the basis of modern physics.

Because light turns out to have a split personality.

It has a wave nature on Mondays, Wednesdays, and Fridays, as one of the physicists said,

and a particle nature on Tuesdays, Thursdays, and Saturdays. Suddenly

young physicists had a big, new, world shattering problem to work on.

And they stack their careers on trying to understand light schizophrenia.

Everything in physics that had been taken for granted was now up for

grabs, and every ambitious young physicists wanted a piece of the action.

It turned into one of the most exciting and creative periods in the history of science,

Quantum physics was born.

Planck's revolutionary explanation of light forced a

fundamental rethink of the basic properties of matter.

And what began to emerge was a whole new world of tiny subatomic

particles no one until now had ever imagined could exist.

To Thomson's discovery of the electron were

added new particles, like neutrons and protons.

This zoo of particles was just impossible to pull together,

physicists for their meat and drink, night and day, try to

work out a better story about how these things could be pulled

together and the problem didn't just stay inside physic labs.

No, physicists would write science fiction stories, make movies

and plays, to trying get the public interested, and they did.

The bubbling excitement eventually resulted in a

completely different picture of what the atom is like.

It is like a planetary system, there is a central nucleus stuffed with neutrons

and protons, and around that nucleus orbit the negatively charged electrons.

But what really mattered was that this atom was bubbling with energy.

The atom itself could be an inexhaustible source of power.

A new physics was born, a physics of the atomic age.

Atomic physics gave us nuclear fission;

a terrifying new power was born.

Out of the ashes, emerges a completely different,

completely new vision of what light really is like,

and it is a very surprising one, because it is a vision of uncertainty, not at all a

mechanical world in which effects follow causes in a rigorous chain of consequences.

This is the world view of modern quantum mechanics, a world view

in which light shifts its character between wave and particle.

It has completely changed the way we think about light, and

it has completely changed the way we think about the world.

Ironically, the more we uncover its mysteries,

the greater those mysteries have grown.

Next on light fantastic, how light gave us trickery

of cinema and Einstein's truth about the universe.