Scotland's Einstein: James Clerk Maxwell - The Man Who Changed the World

BEEPING, JUMBLED VOICES

BEEPING, RADIO INTERFERENCE

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Our planet is filled with signals invisible to the naked eye.

'Two, one, zero...'

But space itself can be just as noisy.

JUMBLED VOICES

This is Cambridge University's Radio Telescope Observatory.

It's used to examine the far reaches of space.

To answer questions about the very origin of our universe.

These magnificent dishes

are detecting signals from radiation

left over from the Big Bang.

But they're not optical telescopes, in the sense of looking

through an eyepiece and seeing a planet or a star.

These dishes are detecting radio waves.

These telescopes allow us to see the unseen.

Extraordinary images like these are made possible

thanks to radio waves...

..microwaves...

..and gamma rays.

The thing is, all these waves are connected.

They're all different types of something we call

electromagnetic radiation.

Visible light - the light that you and I can see -

is just a tiny portion of this broader spectrum of waves.

We use waves to probe the outer reaches of our universe.

But we use them for so much more.

In fact, electromagnetic waves are at the heart of modern technology.

We use them every day, in everything from medicine to communications.

'There it is. There it is.'

Our mastery of these waves was made possible

when one man published a set of equations in 1865.

A man called James Clerk Maxwell.

His name is barely known to the public.

And yet, he's probably the finest scientist Scotland has ever produced.

And 150 years after his greatest discovery,

I'm setting out to explore the story of the man and his work.

Excuse me, can I ask you a question? Do you recognise this person?

No?

Do you know who he is?

Alexander Graham Bell?

No idea.

He looks like a banker... An economist, maybe?

James Clerk Maxwell.

-Still no idea?

-Still no idea.

-James Clerk Maxwell.

-Never heard of him.

-Albert Einstein or something.

-You're so close!

James Clerk Maxwell.

-Name ring a bell?

-Maxwell's equations.

-Maxwell's equations.

I don't know what they're about, but I've heard of them.

-Right, you do physics?

-I do physics.

OK. James Clerk Maxwell, then. This is your test.

I just failed at physics!

-That's his statue.

-Is it?

-That's his statue.

-That's his statue.

-Oh!

-You probably pass that quite regularly.

-Quite regularly,

-so it is quite an embarrassment to say...

-No, but no-one.

I've been asking everyone here.

James Clerk Maxwell.

No-one knows who he is?

Any ideas?

This is a statue of James Clerk Maxwell,

and yet virtually no-one around here knows who he is!

But I don't blame them because Maxwell seems to have slipped through

the cracks of history, at least as far as the public is concerned.

So who was he?

James Clerk Maxwell was a 19th-century Scottish scientist

who used his genius to work across a wide range of subjects.

Astronomy, physiology, colour,

optics, thermodynamics,

electricity and magnetism.

He touched on all of these...

..and changed many of them beyond recognition.

He caused a revolution in physics

and gave us the laws for one of the four fundamental forces

of the universe.

Einstein kept a picture of Maxwell on the wall of his study

and once said, "I stand on the shoulders

"of James Clerk Maxwell."

It's a sentiment shared by many physicists today.

Maxwell did for electricity and magnetism

what Isaac Newton did for gravity.

He's one of my great heroes.

He's one of the greatest scientists we're ever, ever going to encounter.

He's on a par with Einstein,

with Newton, with Archimedes.

He transformed our way in which we understand the world.

He's probably the greatest scientist Scotland has ever produced,

and we're still living in the shadow of his achievements.

And yet, no-one knows who he is!

Even me - a Scot and a scientist -

I've just got this vague notion of what he did.

But I want to change that.

I want to rediscover James Clerk Maxwell.

Born in Edinburgh in 1831,

Maxwell was the only child in a land-owning family from Galloway.

The scientific revolution of the previous centuries was

changing our view of the world.

But modern science was still in its infancy.

The 19th century would see ground-breaking discoveries.

And Maxwell would be at the heart of it, compelled by a probing mind.

His inquisitive nature was obvious, even in childhood.

When he was a boy, the zoetrope was a new invention.

And the young Maxwell loved them.

It's kind of hypnotic. HE CHUCKLES

In a sense, these are the forerunners of movies and television,

and you can imagine kids in the 19th century just

being mesmerised by them.

Most of them would have been happy to just sit back

and enjoy the show, but Maxwell wanted to know how they worked.

The moving figures are a trick of the eye.

Stop the drum spinning,

and you can see the simple sketches that help create the moving image.

This simple illusion captivated Maxwell.

As a child, he would build his own zoetrope strips

to entertain his family and to understand how they worked.

This desire to understand the world around him

continued into adulthood.

Aged just 14, he produced a paper on geometric shapes that showed

such mathematical ingenuity it was published...

..and then read at the Royal Society of Edinburgh

by an established professor, as James was deemed too young.

As a teenager, he conducted home-made experiments

into light and colour.

And by the time he arrived at Cambridge University,

aged 19, he had already published three mathematical papers.

From the age of 14,

Maxwell had been using mathematics to explain how the world worked.

It was a talent he would rely on for many of his discoveries,

and it was key to establishing his scientific reputation.

Because, while still in his 20s, he used maths to solve

a riddle that had puzzled scientists for centuries.

Saturn's rings.

A vivid band surrounding one of our solar system's giant planets.

We've become accustomed to their beauty.

But in previous centuries, they were an enigma.

Galileo first drew them in 1610,

and they immediately fascinated astronomers.

Sometimes the rings were hidden.

At other times, clearly visible in the night sky.

By the mid-19th century, we knew the rings were composed

of at least two vast concentric circles -

over 250,000 kilometres in diameter.

But what were the rings made of?

And why did they stay in place?

In 1855, a Cambridge college published an open competition

to answer those very questions.

But the answer would have to be accompanied by

a full mathematical proof.

Maxwell's response would earn him

his stripes as one of Britain's top physicists.

There were three possible explanations for Saturn's rings.

One possibility was that the rings were solid rock or ice.

Another, that they were entirely fluid.

A third explanation said the rings were made up

of lots of individual particles that circled Saturn.

As the rings were over a billion kilometres away,

proving which explanation was right seemed impossible.

So how did Maxwell go about kind of disentangling those options?

-Well, with great difficulty!

-I bet you!

Of course, what's really striking, what's very impressive,

is that he did it using pure maths.

And you wouldn't perhaps instantly think that this was a problem

you could tackle that way. You'd think, well, the way to do it

is to just build a big telescope and have a look.

But the mathematics that Maxwell brought to bear on this

allowed him to look at these three cases

and to basically decide which one of them was the correct answer.

So if we take first of all the case of a completely solid ring,

there's a particular mathematical equation that describes

that case -

the distance from the centre of the planet to the centre of the rings,

that's this big R here.

MUTED SPEECH

The maths IS incredibly complicated.

And as a geologist, I'm a bit out of my depth!

But I understand the basic point.

Maxwell reduced the physical world to mathematical symbols,

and then used maths to predict what was happening around Saturn.

Maxwell said that a solid ring was possible,

but only if most of the material was bunched together

on one side of the planet.

And, of course, if you look through a telescope, it doesn't look like

that, so that model was discarded.

Back to the drawing board.

Maxwell then assumed that the rings were fluid.

He came up with an equation to describe how that might work.

Off he goes with these complicated mathematics.

He found that if the rings were fluid,

physical forces acting on them would eventually break them up into lumps.

So he discounted this possibility.

And that leaves the third possibility,

which is that the rings consist of a very large number

of independently moving particles,

particles that are all orbiting Saturn,

on their own.

And what he boiled all of that down to was an equation to tell you

how many particles you would need in order to have the system stable.

And sure enough, this seemed to work. So it wasn't just

that he'd shown that the other two possibilities were wrong,

but that this third possibility did actually work as well.

What I find staggering is just the notion that you can just use

numbers to predict something. You've got absolutely,

-you know, no knowledge about it directly.

-Sure.

I think,

for me, that's almost a watershed moment

in how we do physics because, you know, it laid the foundations

for really how we do physics today. Because there's many examples,

everything from, say, the Higgs Boson

to studying distant galaxies,

where you can make theoretical predictions

and it might be years or decades

or even centuries before you can fully test those predictions.

But, hey, it works.

We're just zooming in on the ring plane.

-That's great, isn't it?!

-Yeah, amazing.

-Here we are!

-We're in the ring!

Look at that.

What do you think Maxwell would have given to have seen this?

-HE LAUGHS

-Oh, I'm sure he would have loved it.

Almost 130 years after Maxwell's prediction,

we captured images that proved his theory beyond doubt.

In 1977, an ambitious NASA launched the Voyager probe.

Three years later, it sent home sensational images of Saturn's rings.

In 2009, the Cassini probe confirmed those findings.

Saturn's rings were made of millions of icy rocks.

In recognition of his work,

a division between the rings is known as the Maxwell Gap.

But his maths has been applied beyond Saturn.

This image from the Taurus Constellation

shows a young sun at the heart of a huge cloud of dust and rocks.

As the cloud circles the star,

dark bands reveal areas where rocks

are clumping together to form planets.

We're witnessing the birth of a solar system.

And the maths we use to understand this process

is the same as Maxwell's work on Saturn's rings.

Maths is a powerful tool that physicists use to understand,

to predict the universe.

And Maxwell was a master of it.

In solving the problem of Saturn's rings,

Maxwell had put a marker down -

he wanted the scientific establishment to take him seriously.

And they did.

When Maxwell delivered his paper,

it was the only one that the Cambridge committee received.

No-one else come up with an explanation.

Overnight, Maxwell became known as one of Britain's great

theoretical physicists.

This wasn't a surprise to those who knew him

because his teenage precociousness

had been followed by ground-breaking experiments as an undergraduate.

So perhaps it's no wonder that Maxwell was made professor

here at Aberdeen's Marischal College at the tender age of 25.

His star was on the rise.

His career may have been taking off,

but this was a difficult time for Maxwell.

An only child, he'd been extremely close to his parents.

But his mother had died when he was eight.

And just a few months before Maxwell arrived in Aberdeen,

he lost his father.

Maxwell expressed his grief in a letter to a friend.

But the passage gives a revealing insight into his humanity

and the deep feelings he had for family and friends.

"Either be a machine

"and see nothing but phenomena,

"or else try to be a man,

"feeling your life interwoven, as it is,

"with many others,

"and strengthened by them, whether in life or death."

Maxwell's move to Aberdeen meant he was far from friends

and amongst colleagues twice his age.

He threw himself into his work.

Whether it was his industry or his solitude,

Maxwell came to the attention of the college principal,

Reverend Daniel Dewar.

Dewar befriended his new professor,

and Maxwell became a regular visitor for dinner,

which is how he met the principal's daughter, Katherine.

Maxwell's relationship with Katherine reveals

the character of the man beyond his scientific genius.

Deeply affectionate, he had a lively sense of humour

and a passion for poetry.

As their relationship blossomed,

Maxwell plucked up the courage to ask Katherine to share

their lives together - and his marriage proposal included a poem.

Will you come along with me

In the fresh spring tide

My comforter to be

Through the world so wide?

And the life that we shall lead

In the fresh spring tide

Will make you mine indeed

Though the world so wide

No stranger's blame or praise

Will turn us from our ways

That brought us happy days

On our ain burnside.

Maxwell married Katherine in 1858.

And throughout their lives, they remained devoted to each other.

She would be a valued assistant in many of his future experiments

and even became a willing guinea pig

for one of his great obsessions.

Strange as it may seem, in Maxwell's time,

we didn't really know what colour was, or why we saw colour at all.

In the 17th century, Isaac Newton had given us food for thought.

By using a prism, he had split sunlight into separate

colours - the familiar colours of the rainbow.

He showed that what we perceive as white light

is actually a mixture of different colours.

Newton said that every colour we see was the result of mixing

the colours we see in the rainbow.

He tried - and failed - to establish the rules of mixing.

150 years later, we weren't much wiser.

Maxwell was interested in colour -

and why we perceive it -

throughout his life.

And his first real breakthrough came as a Cambridge student.

Artists seemed to be ahead of scientists on this.

For centuries, they had been creating a vast

palette of colours, often by just mixing red, blue and yellow.

Artists referred to these three as the primary colours -

and using them, they could create entirely different colours.

So if a painter was mixing red and yellow,

they would get orange.

And if he was mixing blue and red, then he'd get purple.

But if he was mixing blue and yellow, then he would get green.

As a student, Maxwell read about the work of Thomas Young.

Young thought that there was something

significant about the number of primary colours.

But he also thought biology had a role to play.

Young argued that the human eye had three receptors in it,

each one sensitive to a particular colour.

He argued that the brain worked like a painter, combining messages

from each receptor to build up this perception of colour.

It was a stroke of intuitive genius.

He just didn't have any proof.

Young thought that these receptors corresponded to the painter's

primary colours.

Taken by Young's three-colour theory,

Maxwell wanted to test it.

He devised a way to mix the primary colours

with mathematical precision.

He then tested those mixtures on a wide range of people

to see if they all perceived the same colour.

And he did this with a deceptively simple tool.

So this looks old. What is this, then?

This is Maxwell's original colour wheel,

which we are very pleased to have in the laboratory.

So that's the original thing.

It's the original thing.

It's slightly beaten up - it's been used a lot.

And that's because Maxwell used this to test out the mixing

of lights among all his friends when he was here in Trinity College.

It is...pretty antique, as you can see,

but the idea is, you put different amounts of the coloured papers here,

and then when you rotate them, then they mix up.

And this works because of the...because of... The typical time

the eye can respond is a 20th of a second.

And so if it goes faster, the eye will interpret this

as a mixture of the colours.

And this is a motorised version of it.

This is a motorised version of it.

And we can actually demonstrate how the colour mixing works with

this rather pretty demonstration here.

We're going to mix red and blue.

We'll rotate it rapidly and then we'll see which colour we produce.

Just like his childhood zoetrope,

Maxwell's colour wheel would spin so fast it would trick the human eye.

-So if you were going to bring up that light...

-This one here?

That's right.

'Instead of moving figures, he'd be mixing colours just as artists did,

'but with mathematical precision.'

When he mixed red and blue, he got the same colour artists did

when they mixed paint.

That's kind of magenta, proper magenta.

Yes, it's a sort of magenta colour.

If Young was right and there were receptors in our eye that

responded to the artist's primary colours, then perhaps mixing

red, yellow and blue in equal measure would produce white.

But it didn't.

So Maxwell tried different combinations.

We can begin now to reveal green, as well as blue here.

And if we just do a little bit of fiddling around with these discs,

we'll be able to get equal amounts of red, green and blue,

and we can then see what colours we observe, OK?

So it's white. I mean, it's white.

It's the only colour you could call that. White.

So this was a beautiful demonstration of the fact

that the primary lights - and notice the word light, not pigment -

the primary lights are red, blue and green.

And you can create any colour of light by suitable mixture

of different proportions of these.

What happens in paintings - pigments absorb light,

whereas this is emitting light.

So the upshot of all of this was that Maxwell was able to produce

a rather beautiful colour triangle diagram

which would indicate how you would create ANY colour

by mixing the three primary colours.

Maxwell's colour triangle allowed him to pick a specific colour

and work out how much of each primary colour would be needed

to reproduce it.

This was made possible by his mathematical precision

and systematic testing.

Maxwell's work swept aside a sea of confusion.

He vindicated Young's theory and demonstrated that we see

colours in paints differently to the way we see colours in light.

He established the primary colours for light as red, blue and green.

He realised the receptors in our eyes were sensitive to those three.

And that by mixing them, we perceived a vast range of colours.

A few years later,

he provided a stunning display that he was right.

In 1861, Maxwell was invited to the Royal Institution in London

to give a lecture on colour vision.

But he didn't want to just talk about the principles,

he wanted to demonstrate them to his audience.

What he did would astonish them.

Maxwell took three photographs of the same object.

Each photo had a different filter on it -

one was red, one was green and one was blue.

That gave Maxwell three photographic plates that he could use

to project an image with.

When Maxwell projected the image from the red photograph

onto the wall, he got a red picture.

In an age when photography was black and white,

this was INTERESTING but hardly revolutionary.

But if you project all three images onto the wall at the exact same spot,

something special happens.

The audience were looking

at the world's first colour photograph.

They were stunned.

Maxwell had chosen the perfect subject for his picture -

a brightly coloured tartan ribbon.

By layering red, green and blue images on top of each other,

Maxwell established the possibility of creating colour photographs.

150 years later, we use this method daily,

because this three-colour principle is used in colour TV,

computer screens, even mobile phones.

The colours we see on our screens, however big or small,

are created by carefully mixing the primary colours.

Maxwell's work on colour provides the basis for our present

understanding of colour vision.

He even proposed an explanation

for why some people were colour-blind.

He said the receptors in their eyes were faulty,

and that this radically altered how they perceived colour.

Three weeks after his colour show, Maxwell was elected to the

Royal Society for his work on Saturn's rings and on colour.

He was now counted amongst the finest physicists in Britain.

And he was 29.

Despite his success,

a year earlier Maxwell had found himself out of a job.

When Marischal College merged with Aberdeen University,

he had lost out to an older professor.

Out of work, Maxwell and Katherine took a trip to the country,

to somewhere very special to James.

A quiet place hidden deep in Galloway, just west of Dumfries.

A place called Glenlair.

His family home.

Maxwell's family had been established in the area

for centuries, and Glenlair was a working estate.

He was born in Edinburgh, but James had spent an idyllic childhood here.

FAINT CHILDREN'S LAUGHTER

Playing in the fields, swimming in the stream,

running through the woods, nature truly was his playground.

And that fostered a curiosity about how the natural world worked.

For the first decade of his life,

Maxwell was home-schooled by his mother.

She encouraged his inquisitiveness.

"Look up through nature," she said, "up to nature's god."

Glenlair remained an important place to Maxwell throughout his life.

It was somewhere that rooted him.

A safe haven. A home.

And the current owner of Glenlair knows just how that feels.

So what was it like growing up at Glenlair?

Well, I was a ten-year-old little boy when I came here,

and I had the run of the place.

My dad was quite an old chap and...

he and my mother - and I was an only child, they were elderly -

so they didn't really keep an eye on me.

My childhood must have almost mirrored his,

although I was slightly older.

But I mean, a lot of his stuff's theoretical.

It's kind of just thinking, difficult thinking.

This seems a good place for theoretical thinkers.

Yes, yes. And we have loads of professors who visit here.

And nearly all of them stand here,

and they look out at that view, and they say,

"I know how he could do it."

Because it just inspires you.

So how do you encapsulate Maxwell? What is he for you?

What do you think of him more than anything else?

What appealed to me about Maxwell

is how normal he was,

as a boy,

that he loved outside.

He loved the open air.

He loved all the creatures.

And the gardens and the trees you see round here,

thanks to Maxwell.

But it's that emotional attachment that you feel to him?

Yes, it's the way he loved it here, like I love it here.

I've been offered lots and lots of money to sell this place,

but there's no way they're going to get me out,

except in a box.

Like Duncan, Maxwell felt a strong connection to Glenlair.

His proposal poem to Katherine had been about sharing their lives

here - they'd even honeymooned in Glenlair.

When they returned here in 1860, it wasn't just a holiday.

On the death of his father,

Maxwell had inherited over 1,000 acres of farmland.

Dozens of working people relied on decisions he made.

There were fields to sow, animals to tend, buildings to construct.

He raised funds to build a church

and was keen to improve local schooling.

It was a responsibility he took seriously.

And every summer, Maxwell and Katherine returned here

to oversee the estate...

..and recapture some of the childhood peace he'd found here.

But Maxwell wouldn't stay at Glenlair.

He wanted to be in the thick of scientific research,

and that meant a university.

After a rejection from Edinburgh,

he accepted a position at King's College, London.

Whilst there, he would produce his finest work

and unravel one of the great mysteries of his age.

Maxwell arrived in London at the end of 1860

and assumed teaching duties immediately.

While there, he focused on a subject that had

captured his attention many years before.

Ever since his early days at Cambridge, Maxwell had been

interested in electricity,

after it was suggested as an area to look at by a friend.

That friend's advice was simple -

if Maxwell wanted to learn something about electricity,

he needed to know Michael Faraday.

Faraday was a self-taught scientist who was revolutionising

our understanding of electricity and magnetism.

Maxwell's relationship with him

was one of the most fruitful in 19th-century science.

We'd known about electricity and magnetism since ancient times.

Most people had experienced the power of electricity through

terrifying lightning storms.

And we'd used magnetism in ships' compasses for centuries.

They were considered completely separate things

for most of our history.

But in the early 19th century,

scientists like Faraday were beginning to see

a mysterious connection between the two.

Deep in the heart of the Royal Institution,

Faraday conducted experiments to understand how they were linked.

In one experiment, a copper wire carrying electricity

somehow provoked a nearby compass to move.

In another, Faraday tried to do the opposite...

..use a magnet to generate electricity.

Which led him to invent

the electric generator, which this is

an example where you have a permanent magnet and

-a coiled wire.

-So the wire's wrapped around this bit.

The wire's wrapped around a cylinder, and you push and pull

the magnet in and out of the cylinder

-to generate an electric current.

-I like the lights.

What's the Christmas lights for, then?

-Well, that's to show that electricity's passing.

-Oh, OK.

-Faraday did NOT use light-emitting diodes.

-I think he should have done.

That was his great mistake!

And all electricity power stations throughout the world

use this principle of generating electricity

that Faraday discovered down here in 1831.

Faraday had generated electricity simply by moving a magnet

through a coiled wire -

a discovery that would forever be associated with his name.

But he was left with perplexing questions.

There was no physical contact between the electric wire

and the magnetic needle that moved

nor between the moving magnet and the copper coil.

They were affecting each other through seemingly thin air.

But how could that be?

Now, what Faraday thought was happening was that there were

lines of force coming out of the end of the magnet,

which were then cutting the wire within the coil

to move electricity around the coil.

The idea of mysterious lines coming out of the magnet to generate

electricity may have seemed outlandish,

but Faraday had a simple experiment that could prove their existence.

So he took a very powerful, permanent magnet.

Placed some paper...

..on it.

Sprinkled iron filings over it.

Just to represent the lines of force...

-It never fails to impress, that, does it?

-..of the magnet.

-And you can see the sort of three dimensional structure.

-Yeah, yeah.

-So these are coming up here and swinging around...

-That's right.

..and then coming down into this bit here.

And Faraday sort of made permanent examples of this and sent them round

to all his mates in Europe, to show that space had structure

as a very strong argument for his field theory.

So Faraday thought there was an invisible force field at work here?

Well, literally a field. Faraday brings the world field

into science. And it's invisible, as you say.

So this is why this is just a representation that shows

-the existence of those invisible lines.

-Yes, absolutely.

Faraday's iron filings experiment revealed

the existence of an invisible field stretching out into thin air.

These fields, he thought,

were responsible for the experimental results he'd seen.

Despite having physical proof,

Faraday lacked a mathematical description of how the field

was generated or why it affected things around it.

Without a mathematical proof,

many 19th-century scientists dismissed the theory as speculative.

But Maxwell had followed Faraday's work for years...

and set out to prove him right.

Maxwell had plenty of time to mull over the problem.

The walk from his Kensington home to King's College

was an eight-mile round trip every day.

And during the walk, he allowed his mind to wander.

On those walks - and at work - he had company.

Apparently, Maxwell always had a dog.

And he always called it the same name!

From childhood onwards, every dog was called Toby.

And Toby - whichever one it was - rarely left his side.

Toby was a constant companion at home and in the lab.

It's a sign of Maxwell's eccentricity

that he would talk to Toby.

He said he liked his company.

During his walks to and from work, Maxwell - and perhaps Toby -

brooded over the mysterious relationship between electricity

and magnetism.

His aim was to provide a mathematical explanation

for the link between the two.

After years of thinking -

and who knows how many miles walking -

he came up with a set of equations

that described the relationship between electricity and magnetism.

Equations that would change our lives forever.

Sorry, Frank, but this is just gobbledygook to me.

I'm just looking at it trying to make sense of it.

Well, it's not much easier for me. I mean...

That's what he wrote first of all. And looking at these,

they probably mean little more to me than to you.

But 20 years later,

they were written in a simpler form which is the way that this...

-This form here.

-That looks more manageable.

But it still looks a bit confusing. Could you take us through it, then?

Right. Well, the first one says that if you've got an electric charge,

it spreads an electric field out all over space.

Just like his work on Saturn's rings,

each equation is a mathematical description of something

observed in the real world.

So the first equation described how a static electric charge

generates an electric field.

And the second, that magnetic poles always come in pairs.

The third equation describes how a changing magnetic field

generates an electric field.

And the fourth equation,

that an electric current surrounds itself with a magnetic field.

But Maxwell realised there was something missing.

Maxwell's genius was to realise that each of these equations is fine

-until you put them together.

-Mm-hm.

And then he realised something was missing,

and it was in this final equation.

He said, "There has to be another term."

And what this extra piece says

is if an electric field is changing,

it will surround itself with a magnetic field.

-Right.

-Which is like the sort of mirror of this equation,

which says if a magnetic field is changing,

it will surround itself with an electric field.

So, just take these two together and just think about it for a second.

If I've got a magnetic field changing,

it surrounds itself with an electric.

If the electric is changing, it surrounds itself with

a magnetic. And if that is changing,

it will surround itself again with an electric, and so on.

Faraday to Maxwell, electric to magnetic back and forth,

-back and forth.

-So there's a coupling, basically, between the two.

Maxwell's equations were saying that electric and magnetic fields

were inextricably linked.

Changes in one created changes in the other.

It helped explain so much.

When Faraday moved his magnet,

he'd changed the position of the magnetic field,

and this triggered an electric field

which caused electricity to flow through the wire.

And when electricity passed through a wire,

it wrapped a magnetic field around it,

causing the compass needle to move.

Using pure maths, Maxwell had unified electricity

and magnetism

and shown they were two aspects of the same thing -

a single electromagnetic field.

This alone would have guaranteed Maxwell's entry

to the scientists hall of fame.

He could have rested on his laurels.

But whether it was his natural curiosity or the long walks

with Toby, he didn't stop there.

He used his equations to test another of Faraday's ideas.

Faraday had guessed that under certain circumstances,

the electric and magnetic field lines could be disturbed by waves

travelling along them -

almost like ripples on the surface of water.

Maxwell used his equations to show that the fields

could fluctuate in time with each other

and cause what Maxwell called an electromagnetic wave.

He could even measure the speed of the wave.

This says the electromagnetic wave travels through space.

And buried in here,

he was able to extract the speed that the wave travels.

And when he put the numbers in, from things that Faraday and others

had already measured, he worked out the speed and it came out as

a phenomenal 300,000 kilometres every second, roughly.

And that, I think, is the moment of discovery because he knew

that people had measured the speed of light,

which was 300,000 kilometres every second.

Now, at this moment you think,

-is this a coincidence or are these equations telling me something?

-Yeah.

And, of course, they're telling you something,

and what the message is - light is an electromagnetic wave.

This was a stunning conclusion.

Maxwell had explained what light itself was.

At the same time, he'd introduced something new to science -

electromagnetic waves - and they were destined to change our planet.

The problem was he hadn't physically demonstrated

the existence of these waves.

It was all in the maths.

Physical proof would have to come later.

His equations were an astonishing piece of work,

packed with radical ideas.

Maxwell gave us a unified theory of electricity and magnetism,

he solved the mystery of what light was and he predicted the existence

of these invisible fields that would directly affect our life.

That's difficult enough to grasp for a 21st-century scientist,

but what on earth did the Victorians think?

The fact is Maxwell was asking a lot from his peers.

Invisible fields, undetected waves,

dense maths -

it was all a bit much for 19th-century scientists.

Ironically, Maxwell found himself in a similar position to Faraday -

surrounded by sceptical colleagues

and lacking the proof to vindicate his theory.

But a jubilant Maxwell was undeterred -

he wrote an excited letter to his cousin.

"I also have a paper afloat, with

"an electromagnetic theory of light,

"which until I'm convinced to the contrary, I hold to be great guns."

The guns may have fired,

but it would be a while before they would be heard.

It took more than 20 years before a German scientist called

Heinrich Hertz found physical proof for electromagnetic waves.

When he was asked what practical use the wave had,

he replied, "It's of no use whatsoever.

"This is just an experiment that proves Maestro Maxwell was right."

How wrong he was, because Hertz had discovered radio waves.

Marconi invented the radio, and since then, we've been

using them to spread radio and television all over the planet.

But this was just the first in a long list of discoveries.

# Happy days are here again... #

Using higher frequency radio waves, we developed radar,

which now gets used in everything from aviation to geology.

Microwaves were discovered, which we use in cooking

and when we use a mobile phone.

Infrared is used in thermal imaging

and in most TV remote controls.

Ultraviolet is used in fluorescent lamps,

security marking and medical research.

X-rays have provided us with a valuable medical tool,

but more recently in security.

And gamma rays have been used to

detect and treat cancer, and even to sterilise the food we eat.

All these things are connected.

Maxwell had shown that light and the colours we see

are electromagnetic waves.

But he predicted there would be more.

Today, we know that visible light is just a tiny sliver

of a broad spectrum of electromagnetic waves.

And by understanding

and exploiting them,

we've revolutionised our world,

all thanks to equations

Maxwell published 150 years ago.

That was all part of a future that Maxwell wouldn't see.

When he first published, people didn't understand him.

You know, back in 1865, there was no sign, no evidence of these mysterious

electromagnetic waves.

Maxwell was asking people to believe that these waves could pass

through empty space and affect things at a distance.

It was just too much to ask.

His equations were initially met with a bewildered silence.

19th-century scientists were used to

thinking of the world in mechanical terms -

physically tangible objects that could be touched, measured and felt.

Flying in the face of that was Maxwell's theory -

based on dense mathematics,

invisible fields and undetected waves.

Many thought Maxwell's theory

was a kind of abstract mathematical speculation.

That he had strayed too far from physical reality.

That he was, in essence, away with the fairies.

Maxwell became convinced that he had to develop his theory

of magnetism and electricity.

Not long after that publication,

he decided to pursue his own interests

and resigned his post at King's.

He was going home.

After the lukewarm reaction to his 1865 publication,

the comfort of Glenlair was welcome.

Ever industrious, Maxwell produced papers on thermodynamics

and even topology.

But always he returned to his electromagnetic theory,

slowly refining it.

After six years in the wilderness, Cambridge University approached him.

They wanted someone to plan and run a lab in Experimental Physics.

Despite all his achievements, Maxwell was third in line,

after two other candidates had rejected the offer.

In 1871, he left Glenlair for Cambridge,

where he designed and built the Cavendish Laboratory,

which would be responsible for discoveries that shaped physics

in the 20th century.

And as its first director,

his open-minded approach set the tone for subsequent generations.

"I never try to dissuade

"a man from trying an experiment.

"If he does not find out

"what he wants,

"he may find out something else."

The Cavendish Lab would become a phenomenal success.

It's within these walls that we discovered the electron

and later on the neutron.

Watson and Crick were working here when, in 1953,

X-rays were used to show the structure of DNA.

The Cavendish is now widely regarded as a centre of excellence,

and it's produced 29 Nobel Prize winners to date.

But every summer, Maxwell returned to Glenlair,

patiently working out the full implications

of his electromagnetic theory of light.

In 1873, Maxwell released

a dynamical theory of electricity and magnetism.

The intervening years had allowed his colleagues time to digest

his theory, and it was starting to gain traction.

But he wouldn't live to see it vindicated.

When guests were visiting Glenlair in 1879,

Maxwell found he could barely walk down to the river, such was the pain.

The pain was in his stomach.

In October of that year,

he was diagnosed with abdominal cancer,

given a month to live.

Maxwell was just 48 when he received the news.

He knew his mother had died at the same age, from the same disease.

Nevertheless, he accepted his fate

with the calm stoicism that had defined his life.

Katherine nursed him as best she could.

It's said that on his deathbed, Maxwell breathed deeply,

and with a long look at his wife, passed away.

James Clerk Maxwell died in November 1879.

He was buried in Parton Kirk,

his childhood church, just a few miles from his beloved Glenlair.

He lies in a modest grave next to his parents.

And seven years later, Katherine would be buried next to him.

Apart from a plaque outside the cemetery,

there's nothing to mark this grave as different

from any of the others.

There's no list of grand achievements.

It's just simple and modest, like the man himself.

A visitor could be forgiven for passing the grave

without a second glance.

But for some, this is a special place.

There is a story that is told around Parton Kirk.

Shortly after the fall of the Berlin Wall, two buses arrived,

and people filed into the graveyard.

A curious local asked who they were.

They were, they said, Russian scientists who had travelled

to visit the grave of Scotland's Einstein.

You know, Maxwell died at a relatively young age, 48,

which even by the standards of his day, was an untimely death.

And you just wonder,

given the achievements that he had in his lifetime,

what he would have conjured up if he'd lived until he was 60 or 70.

Maxwell may not have been fully appreciated in his time,

but in the decades following his death, scientists started

to recognise his genius.

Eight years after Maxwell's death,

Heinrich Hertz discovered radio waves,

proving beyond doubt the existence of electromagnetic waves.

The rest, as they say, is history.

Over a century later, these waves have changed our planet

and are part of our everyday lives.

But focusing on the technological results of his work

diminishes its importance,

because he changed the way we understand reality itself.

Before the work

of Maxwell, and Faraday just before him,

the experiments, we understood the world in terms

of springs and cogs,

a machine-like world.

And that machine-like world was pretty primitive.

What Maxwell's work showed is that the way that we understand

the interaction between material bodies is via

this idea of a field, not the sort of field we're standing in.

-Not a green field?

-Not a green field but something that penetrates

space and which really governs the way that the world behaves.

Maxwell helped overthrow the mechanical model of the universe

that physicists had held since Newton

and issued in a new era.

We now think of all the forces in the universe interacting

through fields rather than direct physical contact.

This was a crucial shift in our understanding,

prompting Einstein to say, "One scientific epoch ended

"and another began with James Clerk Maxwell."

Which is, perhaps, why he's still revered by scientists today.

This meeting we're having here in Edinburgh today is very special.

We're celebrating

the 150th anniversary of Maxwell's

publication of his equations of electromagnetism.

Some of Britain's finest scientists gather at an event to remember

the life and work of James Clerk Maxwell.

Maxwell is all around us.

Every single piece of technology

that is around us today -

computing, fibre optics,

cameras, mobile phones, everything depends

on extensions of those Maxwell's equations.

Without those, we wouldn't be where we are today.

Even the internet doesn't exist without them.

Maxwell changed the way we think forever.

'You can't overestimate his contribution,

'his influence on everything,

'both practical and theoretical.'

He is the most remarkable Scot, intellectually,

that has ever arisen.

No question about it.

In terms of the sequence of the great men of physics,

starting with Galileo and Newton,

then comes Maxwell

and then Einstein,

who said that

Maxwell was the greatest physicist after Newton.

It's wonderful to be sitting in the audience of a meeting

surrounded by Nobel Prize winners, the great and the good.

There's a sense of shared excitement that you...

This unapologetic geekiness that however much...

You know, people like Peter Higgs

and Nobel Prize winners, we are still in awe

of this giant of physics.

And having got to know the man, I can understand why.

I can't blame people for not knowing about James Clerk Maxwell -

this is difficult stuff!

I just think that, given the breadth of his discoveries

and the sheer impact they've had, it's a travesty

that Maxwell's name's not up there with Newton and Einstein

as one of the greats.

Maxwell is Scotland's Einstein, and we should remember him as such.