0:00:03 > 0:00:04BEEPING, JUMBLED VOICES
0:00:13 > 0:00:16BEEPING, RADIO INTERFERENCE
0:00:16 > 0:00:19JUMBLED VOICES
0:00:19 > 0:00:23Our planet is filled with signals invisible to the naked eye.
0:00:23 > 0:00:26'Two, one, zero...'
0:00:26 > 0:00:29But space itself can be just as noisy.
0:00:33 > 0:00:36JUMBLED VOICES
0:00:36 > 0:00:40This is Cambridge University's Radio Telescope Observatory.
0:00:42 > 0:00:45It's used to examine the far reaches of space.
0:00:47 > 0:00:51To answer questions about the very origin of our universe.
0:00:54 > 0:00:55These magnificent dishes
0:00:55 > 0:00:57are detecting signals from radiation
0:00:57 > 0:00:59left over from the Big Bang.
0:00:59 > 0:01:02But they're not optical telescopes, in the sense of looking
0:01:02 > 0:01:05through an eyepiece and seeing a planet or a star.
0:01:05 > 0:01:08These dishes are detecting radio waves.
0:01:11 > 0:01:15These telescopes allow us to see the unseen.
0:01:19 > 0:01:22Extraordinary images like these are made possible
0:01:22 > 0:01:24thanks to radio waves...
0:01:26 > 0:01:27..microwaves...
0:01:29 > 0:01:30..and gamma rays.
0:01:32 > 0:01:34The thing is, all these waves are connected.
0:01:34 > 0:01:37They're all different types of something we call
0:01:37 > 0:01:39electromagnetic radiation.
0:01:39 > 0:01:41Visible light - the light that you and I can see -
0:01:41 > 0:01:46is just a tiny portion of this broader spectrum of waves.
0:01:46 > 0:01:50We use waves to probe the outer reaches of our universe.
0:01:50 > 0:01:52But we use them for so much more.
0:01:54 > 0:01:58In fact, electromagnetic waves are at the heart of modern technology.
0:01:58 > 0:02:02We use them every day, in everything from medicine to communications.
0:02:02 > 0:02:06'There it is. There it is.'
0:02:07 > 0:02:10Our mastery of these waves was made possible
0:02:10 > 0:02:16when one man published a set of equations in 1865.
0:02:16 > 0:02:20A man called James Clerk Maxwell.
0:02:21 > 0:02:23His name is barely known to the public.
0:02:23 > 0:02:28And yet, he's probably the finest scientist Scotland has ever produced.
0:02:28 > 0:02:31And 150 years after his greatest discovery,
0:02:31 > 0:02:34I'm setting out to explore the story of the man and his work.
0:02:43 > 0:02:46Excuse me, can I ask you a question? Do you recognise this person?
0:02:46 > 0:02:48No?
0:02:48 > 0:02:49Do you know who he is?
0:02:49 > 0:02:51Alexander Graham Bell?
0:02:51 > 0:02:52No idea.
0:02:52 > 0:02:55He looks like a banker... An economist, maybe?
0:02:55 > 0:02:57James Clerk Maxwell.
0:02:59 > 0:03:00- Still no idea?- Still no idea.
0:03:00 > 0:03:03- James Clerk Maxwell. - Never heard of him.
0:03:05 > 0:03:08- Albert Einstein or something. - You're so close!
0:03:08 > 0:03:10James Clerk Maxwell.
0:03:10 > 0:03:13- Name ring a bell?- Maxwell's equations.- Maxwell's equations.
0:03:13 > 0:03:16I don't know what they're about, but I've heard of them.
0:03:16 > 0:03:18- Right, you do physics?- I do physics.
0:03:18 > 0:03:21OK. James Clerk Maxwell, then. This is your test.
0:03:21 > 0:03:23I just failed at physics!
0:03:23 > 0:03:25- That's his statue.- Is it? - That's his statue.
0:03:25 > 0:03:27- That's his statue.- Oh!
0:03:27 > 0:03:30- You probably pass that quite regularly.- Quite regularly,
0:03:30 > 0:03:32- so it is quite an embarrassment to say...- No, but no-one.
0:03:32 > 0:03:33I've been asking everyone here.
0:03:33 > 0:03:35James Clerk Maxwell.
0:03:36 > 0:03:38No-one knows who he is?
0:03:40 > 0:03:41Any ideas?
0:03:44 > 0:03:47This is a statue of James Clerk Maxwell,
0:03:47 > 0:03:50and yet virtually no-one around here knows who he is!
0:03:50 > 0:03:53But I don't blame them because Maxwell seems to have slipped through
0:03:53 > 0:03:57the cracks of history, at least as far as the public is concerned.
0:03:57 > 0:03:58So who was he?
0:04:02 > 0:04:06James Clerk Maxwell was a 19th-century Scottish scientist
0:04:06 > 0:04:10who used his genius to work across a wide range of subjects.
0:04:11 > 0:04:14Astronomy, physiology, colour,
0:04:14 > 0:04:17optics, thermodynamics,
0:04:17 > 0:04:19electricity and magnetism.
0:04:20 > 0:04:22He touched on all of these...
0:04:23 > 0:04:26..and changed many of them beyond recognition.
0:04:27 > 0:04:30He caused a revolution in physics
0:04:30 > 0:04:33and gave us the laws for one of the four fundamental forces
0:04:33 > 0:04:35of the universe.
0:04:36 > 0:04:40Einstein kept a picture of Maxwell on the wall of his study
0:04:40 > 0:04:43and once said, "I stand on the shoulders
0:04:43 > 0:04:44"of James Clerk Maxwell."
0:04:46 > 0:04:48It's a sentiment shared by many physicists today.
0:04:49 > 0:04:52Maxwell did for electricity and magnetism
0:04:52 > 0:04:53what Isaac Newton did for gravity.
0:04:53 > 0:04:55He's one of my great heroes.
0:04:55 > 0:04:58He's one of the greatest scientists we're ever, ever going to encounter.
0:04:58 > 0:05:00He's on a par with Einstein,
0:05:00 > 0:05:03with Newton, with Archimedes.
0:05:03 > 0:05:06He transformed our way in which we understand the world.
0:05:06 > 0:05:09He's probably the greatest scientist Scotland has ever produced,
0:05:09 > 0:05:12and we're still living in the shadow of his achievements.
0:05:12 > 0:05:14And yet, no-one knows who he is!
0:05:14 > 0:05:16Even me - a Scot and a scientist -
0:05:16 > 0:05:20I've just got this vague notion of what he did.
0:05:20 > 0:05:22But I want to change that.
0:05:22 > 0:05:24I want to rediscover James Clerk Maxwell.
0:05:33 > 0:05:35Born in Edinburgh in 1831,
0:05:35 > 0:05:39Maxwell was the only child in a land-owning family from Galloway.
0:05:42 > 0:05:45The scientific revolution of the previous centuries was
0:05:45 > 0:05:47changing our view of the world.
0:05:48 > 0:05:51But modern science was still in its infancy.
0:05:55 > 0:05:58The 19th century would see ground-breaking discoveries.
0:06:02 > 0:06:06And Maxwell would be at the heart of it, compelled by a probing mind.
0:06:24 > 0:06:29His inquisitive nature was obvious, even in childhood.
0:06:29 > 0:06:32When he was a boy, the zoetrope was a new invention.
0:06:32 > 0:06:34And the young Maxwell loved them.
0:06:37 > 0:06:40It's kind of hypnotic. HE CHUCKLES
0:06:40 > 0:06:43In a sense, these are the forerunners of movies and television,
0:06:43 > 0:06:46and you can imagine kids in the 19th century just
0:06:46 > 0:06:48being mesmerised by them.
0:06:48 > 0:06:51Most of them would have been happy to just sit back
0:06:51 > 0:06:54and enjoy the show, but Maxwell wanted to know how they worked.
0:07:00 > 0:07:03The moving figures are a trick of the eye.
0:07:03 > 0:07:05Stop the drum spinning,
0:07:05 > 0:07:09and you can see the simple sketches that help create the moving image.
0:07:11 > 0:07:14This simple illusion captivated Maxwell.
0:07:14 > 0:07:17As a child, he would build his own zoetrope strips
0:07:17 > 0:07:21to entertain his family and to understand how they worked.
0:07:22 > 0:07:25This desire to understand the world around him
0:07:25 > 0:07:27continued into adulthood.
0:07:30 > 0:07:35Aged just 14, he produced a paper on geometric shapes that showed
0:07:35 > 0:07:38such mathematical ingenuity it was published...
0:07:40 > 0:07:43..and then read at the Royal Society of Edinburgh
0:07:43 > 0:07:46by an established professor, as James was deemed too young.
0:07:48 > 0:07:51As a teenager, he conducted home-made experiments
0:07:51 > 0:07:52into light and colour.
0:07:55 > 0:07:57And by the time he arrived at Cambridge University,
0:07:57 > 0:08:01aged 19, he had already published three mathematical papers.
0:08:05 > 0:08:07From the age of 14,
0:08:07 > 0:08:11Maxwell had been using mathematics to explain how the world worked.
0:08:12 > 0:08:15It was a talent he would rely on for many of his discoveries,
0:08:15 > 0:08:20and it was key to establishing his scientific reputation.
0:08:20 > 0:08:24Because, while still in his 20s, he used maths to solve
0:08:24 > 0:08:27a riddle that had puzzled scientists for centuries.
0:08:34 > 0:08:36Saturn's rings.
0:08:36 > 0:08:40A vivid band surrounding one of our solar system's giant planets.
0:08:40 > 0:08:43We've become accustomed to their beauty.
0:08:44 > 0:08:47But in previous centuries, they were an enigma.
0:08:48 > 0:08:51Galileo first drew them in 1610,
0:08:51 > 0:08:55and they immediately fascinated astronomers.
0:08:55 > 0:08:56Sometimes the rings were hidden.
0:08:57 > 0:09:01At other times, clearly visible in the night sky.
0:09:03 > 0:09:07By the mid-19th century, we knew the rings were composed
0:09:07 > 0:09:10of at least two vast concentric circles -
0:09:10 > 0:09:13over 250,000 kilometres in diameter.
0:09:16 > 0:09:18But what were the rings made of?
0:09:18 > 0:09:20And why did they stay in place?
0:09:20 > 0:09:25In 1855, a Cambridge college published an open competition
0:09:25 > 0:09:27to answer those very questions.
0:09:27 > 0:09:30But the answer would have to be accompanied by
0:09:30 > 0:09:32a full mathematical proof.
0:09:32 > 0:09:34Maxwell's response would earn him
0:09:34 > 0:09:37his stripes as one of Britain's top physicists.
0:09:40 > 0:09:44There were three possible explanations for Saturn's rings.
0:09:44 > 0:09:48One possibility was that the rings were solid rock or ice.
0:09:48 > 0:09:52Another, that they were entirely fluid.
0:09:52 > 0:09:54A third explanation said the rings were made up
0:09:54 > 0:09:58of lots of individual particles that circled Saturn.
0:09:59 > 0:10:02As the rings were over a billion kilometres away,
0:10:02 > 0:10:05proving which explanation was right seemed impossible.
0:10:08 > 0:10:11So how did Maxwell go about kind of disentangling those options?
0:10:11 > 0:10:13- Well, with great difficulty! - I bet you!
0:10:13 > 0:10:16Of course, what's really striking, what's very impressive,
0:10:16 > 0:10:18is that he did it using pure maths.
0:10:18 > 0:10:21And you wouldn't perhaps instantly think that this was a problem
0:10:21 > 0:10:23you could tackle that way. You'd think, well, the way to do it
0:10:23 > 0:10:25is to just build a big telescope and have a look.
0:10:25 > 0:10:29But the mathematics that Maxwell brought to bear on this
0:10:29 > 0:10:32allowed him to look at these three cases
0:10:32 > 0:10:35and to basically decide which one of them was the correct answer.
0:10:35 > 0:10:40So if we take first of all the case of a completely solid ring,
0:10:40 > 0:10:44there's a particular mathematical equation that describes
0:10:44 > 0:10:45that case -
0:10:45 > 0:10:48the distance from the centre of the planet to the centre of the rings,
0:10:48 > 0:10:51that's this big R here.
0:10:51 > 0:10:53MUTED SPEECH
0:10:53 > 0:10:56The maths IS incredibly complicated.
0:10:56 > 0:10:59And as a geologist, I'm a bit out of my depth!
0:11:00 > 0:11:03But I understand the basic point.
0:11:03 > 0:11:07Maxwell reduced the physical world to mathematical symbols,
0:11:07 > 0:11:10and then used maths to predict what was happening around Saturn.
0:11:13 > 0:11:16Maxwell said that a solid ring was possible,
0:11:16 > 0:11:19but only if most of the material was bunched together
0:11:19 > 0:11:21on one side of the planet.
0:11:21 > 0:11:24And, of course, if you look through a telescope, it doesn't look like
0:11:24 > 0:11:26that, so that model was discarded.
0:11:26 > 0:11:28Back to the drawing board.
0:11:28 > 0:11:31Maxwell then assumed that the rings were fluid.
0:11:31 > 0:11:34He came up with an equation to describe how that might work.
0:11:34 > 0:11:37Off he goes with these complicated mathematics.
0:11:38 > 0:11:40He found that if the rings were fluid,
0:11:40 > 0:11:45physical forces acting on them would eventually break them up into lumps.
0:11:45 > 0:11:48So he discounted this possibility.
0:11:48 > 0:11:51And that leaves the third possibility,
0:11:51 > 0:11:53which is that the rings consist of a very large number
0:11:53 > 0:11:55of independently moving particles,
0:11:55 > 0:11:58particles that are all orbiting Saturn,
0:11:58 > 0:11:59on their own.
0:11:59 > 0:12:04And what he boiled all of that down to was an equation to tell you
0:12:04 > 0:12:08how many particles you would need in order to have the system stable.
0:12:08 > 0:12:11And sure enough, this seemed to work. So it wasn't just
0:12:11 > 0:12:15that he'd shown that the other two possibilities were wrong,
0:12:15 > 0:12:18but that this third possibility did actually work as well.
0:12:18 > 0:12:21What I find staggering is just the notion that you can just use
0:12:21 > 0:12:24numbers to predict something. You've got absolutely,
0:12:24 > 0:12:26- you know, no knowledge about it directly.- Sure.
0:12:26 > 0:12:28I think,
0:12:28 > 0:12:31for me, that's almost a watershed moment
0:12:31 > 0:12:34in how we do physics because, you know, it laid the foundations
0:12:34 > 0:12:37for really how we do physics today. Because there's many examples,
0:12:37 > 0:12:39everything from, say, the Higgs Boson
0:12:39 > 0:12:41to studying distant galaxies,
0:12:41 > 0:12:43where you can make theoretical predictions
0:12:43 > 0:12:45and it might be years or decades
0:12:45 > 0:12:48or even centuries before you can fully test those predictions.
0:12:48 > 0:12:49But, hey, it works.
0:12:52 > 0:12:54We're just zooming in on the ring plane.
0:12:57 > 0:13:00- That's great, isn't it?! - Yeah, amazing.
0:13:04 > 0:13:07- Here we are!- We're in the ring!
0:13:07 > 0:13:08Look at that.
0:13:08 > 0:13:11What do you think Maxwell would have given to have seen this?
0:13:11 > 0:13:13- HE LAUGHS - Oh, I'm sure he would have loved it.
0:13:15 > 0:13:19Almost 130 years after Maxwell's prediction,
0:13:19 > 0:13:22we captured images that proved his theory beyond doubt.
0:13:26 > 0:13:31In 1977, an ambitious NASA launched the Voyager probe.
0:13:32 > 0:13:37Three years later, it sent home sensational images of Saturn's rings.
0:13:39 > 0:13:43In 2009, the Cassini probe confirmed those findings.
0:13:43 > 0:13:47Saturn's rings were made of millions of icy rocks.
0:13:49 > 0:13:50In recognition of his work,
0:13:50 > 0:13:54a division between the rings is known as the Maxwell Gap.
0:13:56 > 0:13:59But his maths has been applied beyond Saturn.
0:14:03 > 0:14:06This image from the Taurus Constellation
0:14:06 > 0:14:11shows a young sun at the heart of a huge cloud of dust and rocks.
0:14:12 > 0:14:14As the cloud circles the star,
0:14:14 > 0:14:16dark bands reveal areas where rocks
0:14:16 > 0:14:19are clumping together to form planets.
0:14:21 > 0:14:24We're witnessing the birth of a solar system.
0:14:26 > 0:14:30And the maths we use to understand this process
0:14:30 > 0:14:33is the same as Maxwell's work on Saturn's rings.
0:14:36 > 0:14:40Maths is a powerful tool that physicists use to understand,
0:14:40 > 0:14:41to predict the universe.
0:14:41 > 0:14:43And Maxwell was a master of it.
0:14:43 > 0:14:45In solving the problem of Saturn's rings,
0:14:45 > 0:14:47Maxwell had put a marker down -
0:14:47 > 0:14:51he wanted the scientific establishment to take him seriously.
0:14:51 > 0:14:52And they did.
0:14:56 > 0:14:57When Maxwell delivered his paper,
0:14:57 > 0:15:01it was the only one that the Cambridge committee received.
0:15:01 > 0:15:03No-one else come up with an explanation.
0:15:04 > 0:15:07Overnight, Maxwell became known as one of Britain's great
0:15:07 > 0:15:09theoretical physicists.
0:15:10 > 0:15:13This wasn't a surprise to those who knew him
0:15:13 > 0:15:15because his teenage precociousness
0:15:15 > 0:15:20had been followed by ground-breaking experiments as an undergraduate.
0:15:20 > 0:15:23So perhaps it's no wonder that Maxwell was made professor
0:15:23 > 0:15:27here at Aberdeen's Marischal College at the tender age of 25.
0:15:27 > 0:15:29His star was on the rise.
0:15:32 > 0:15:34His career may have been taking off,
0:15:34 > 0:15:38but this was a difficult time for Maxwell.
0:15:38 > 0:15:42An only child, he'd been extremely close to his parents.
0:15:42 > 0:15:44But his mother had died when he was eight.
0:15:44 > 0:15:47And just a few months before Maxwell arrived in Aberdeen,
0:15:47 > 0:15:48he lost his father.
0:15:50 > 0:15:53Maxwell expressed his grief in a letter to a friend.
0:15:53 > 0:15:57But the passage gives a revealing insight into his humanity
0:15:57 > 0:16:00and the deep feelings he had for family and friends.
0:16:01 > 0:16:03"Either be a machine
0:16:03 > 0:16:05"and see nothing but phenomena,
0:16:05 > 0:16:08"or else try to be a man,
0:16:08 > 0:16:09"feeling your life interwoven, as it is,
0:16:09 > 0:16:11"with many others,
0:16:11 > 0:16:15"and strengthened by them, whether in life or death."
0:16:17 > 0:16:20Maxwell's move to Aberdeen meant he was far from friends
0:16:20 > 0:16:23and amongst colleagues twice his age.
0:16:25 > 0:16:26He threw himself into his work.
0:16:28 > 0:16:31Whether it was his industry or his solitude,
0:16:31 > 0:16:34Maxwell came to the attention of the college principal,
0:16:34 > 0:16:35Reverend Daniel Dewar.
0:16:37 > 0:16:39Dewar befriended his new professor,
0:16:39 > 0:16:42and Maxwell became a regular visitor for dinner,
0:16:42 > 0:16:46which is how he met the principal's daughter, Katherine.
0:16:47 > 0:16:49Maxwell's relationship with Katherine reveals
0:16:49 > 0:16:54the character of the man beyond his scientific genius.
0:16:54 > 0:16:56Deeply affectionate, he had a lively sense of humour
0:16:56 > 0:16:58and a passion for poetry.
0:16:59 > 0:17:01As their relationship blossomed,
0:17:01 > 0:17:04Maxwell plucked up the courage to ask Katherine to share
0:17:04 > 0:17:08their lives together - and his marriage proposal included a poem.
0:17:09 > 0:17:11Will you come along with me
0:17:11 > 0:17:13In the fresh spring tide
0:17:13 > 0:17:14My comforter to be
0:17:14 > 0:17:16Through the world so wide?
0:17:16 > 0:17:18And the life that we shall lead
0:17:18 > 0:17:20In the fresh spring tide
0:17:20 > 0:17:22Will make you mine indeed
0:17:22 > 0:17:24Though the world so wide
0:17:24 > 0:17:27No stranger's blame or praise
0:17:27 > 0:17:28Will turn us from our ways
0:17:28 > 0:17:30That brought us happy days
0:17:30 > 0:17:32On our ain burnside.
0:17:35 > 0:17:38Maxwell married Katherine in 1858.
0:17:38 > 0:17:42And throughout their lives, they remained devoted to each other.
0:17:44 > 0:17:48She would be a valued assistant in many of his future experiments
0:17:48 > 0:17:50and even became a willing guinea pig
0:17:50 > 0:17:52for one of his great obsessions.
0:18:00 > 0:18:03Strange as it may seem, in Maxwell's time,
0:18:03 > 0:18:07we didn't really know what colour was, or why we saw colour at all.
0:18:09 > 0:18:13In the 17th century, Isaac Newton had given us food for thought.
0:18:14 > 0:18:18By using a prism, he had split sunlight into separate
0:18:18 > 0:18:20colours - the familiar colours of the rainbow.
0:18:23 > 0:18:25He showed that what we perceive as white light
0:18:25 > 0:18:28is actually a mixture of different colours.
0:18:31 > 0:18:35Newton said that every colour we see was the result of mixing
0:18:35 > 0:18:37the colours we see in the rainbow.
0:18:37 > 0:18:41He tried - and failed - to establish the rules of mixing.
0:18:43 > 0:18:46150 years later, we weren't much wiser.
0:18:46 > 0:18:48Maxwell was interested in colour -
0:18:48 > 0:18:50and why we perceive it -
0:18:50 > 0:18:51throughout his life.
0:18:55 > 0:18:59And his first real breakthrough came as a Cambridge student.
0:19:01 > 0:19:04Artists seemed to be ahead of scientists on this.
0:19:07 > 0:19:09For centuries, they had been creating a vast
0:19:09 > 0:19:14palette of colours, often by just mixing red, blue and yellow.
0:19:17 > 0:19:20Artists referred to these three as the primary colours -
0:19:20 > 0:19:24and using them, they could create entirely different colours.
0:19:24 > 0:19:28So if a painter was mixing red and yellow,
0:19:28 > 0:19:29they would get orange.
0:19:31 > 0:19:34And if he was mixing blue and red, then he'd get purple.
0:19:37 > 0:19:41But if he was mixing blue and yellow, then he would get green.
0:19:43 > 0:19:48As a student, Maxwell read about the work of Thomas Young.
0:19:48 > 0:19:50Young thought that there was something
0:19:50 > 0:19:53significant about the number of primary colours.
0:19:54 > 0:19:57But he also thought biology had a role to play.
0:19:58 > 0:20:01Young argued that the human eye had three receptors in it,
0:20:01 > 0:20:05each one sensitive to a particular colour.
0:20:05 > 0:20:08He argued that the brain worked like a painter, combining messages
0:20:08 > 0:20:12from each receptor to build up this perception of colour.
0:20:14 > 0:20:17It was a stroke of intuitive genius.
0:20:17 > 0:20:18He just didn't have any proof.
0:20:23 > 0:20:27Young thought that these receptors corresponded to the painter's
0:20:27 > 0:20:29primary colours.
0:20:29 > 0:20:32Taken by Young's three-colour theory,
0:20:32 > 0:20:34Maxwell wanted to test it.
0:20:36 > 0:20:38He devised a way to mix the primary colours
0:20:38 > 0:20:40with mathematical precision.
0:20:41 > 0:20:45He then tested those mixtures on a wide range of people
0:20:45 > 0:20:48to see if they all perceived the same colour.
0:20:49 > 0:20:52And he did this with a deceptively simple tool.
0:20:54 > 0:20:56So this looks old. What is this, then?
0:20:56 > 0:20:59This is Maxwell's original colour wheel,
0:20:59 > 0:21:01which we are very pleased to have in the laboratory.
0:21:01 > 0:21:03So that's the original thing.
0:21:03 > 0:21:04It's the original thing.
0:21:04 > 0:21:07It's slightly beaten up - it's been used a lot.
0:21:07 > 0:21:11And that's because Maxwell used this to test out the mixing
0:21:11 > 0:21:15of lights among all his friends when he was here in Trinity College.
0:21:15 > 0:21:18It is...pretty antique, as you can see,
0:21:18 > 0:21:23but the idea is, you put different amounts of the coloured papers here,
0:21:23 > 0:21:26and then when you rotate them, then they mix up.
0:21:26 > 0:21:31And this works because of the...because of... The typical time
0:21:31 > 0:21:34the eye can respond is a 20th of a second.
0:21:34 > 0:21:37And so if it goes faster, the eye will interpret this
0:21:37 > 0:21:38as a mixture of the colours.
0:21:38 > 0:21:40And this is a motorised version of it.
0:21:40 > 0:21:41This is a motorised version of it.
0:21:41 > 0:21:45And we can actually demonstrate how the colour mixing works with
0:21:45 > 0:21:48this rather pretty demonstration here.
0:21:48 > 0:21:50We're going to mix red and blue.
0:21:50 > 0:21:54We'll rotate it rapidly and then we'll see which colour we produce.
0:21:56 > 0:21:58Just like his childhood zoetrope,
0:21:58 > 0:22:03Maxwell's colour wheel would spin so fast it would trick the human eye.
0:22:03 > 0:22:06- So if you were going to bring up that light...- This one here?
0:22:06 > 0:22:07That's right.
0:22:07 > 0:22:11'Instead of moving figures, he'd be mixing colours just as artists did,
0:22:11 > 0:22:14'but with mathematical precision.'
0:22:16 > 0:22:20When he mixed red and blue, he got the same colour artists did
0:22:20 > 0:22:21when they mixed paint.
0:22:21 > 0:22:24That's kind of magenta, proper magenta.
0:22:24 > 0:22:26Yes, it's a sort of magenta colour.
0:22:26 > 0:22:29If Young was right and there were receptors in our eye that
0:22:29 > 0:22:33responded to the artist's primary colours, then perhaps mixing
0:22:33 > 0:22:36red, yellow and blue in equal measure would produce white.
0:22:38 > 0:22:40But it didn't.
0:22:40 > 0:22:43So Maxwell tried different combinations.
0:22:43 > 0:22:48We can begin now to reveal green, as well as blue here.
0:22:48 > 0:22:52And if we just do a little bit of fiddling around with these discs,
0:22:52 > 0:22:56we'll be able to get equal amounts of red, green and blue,
0:22:56 > 0:23:00and we can then see what colours we observe, OK?
0:23:17 > 0:23:19So it's white. I mean, it's white.
0:23:19 > 0:23:22It's the only colour you could call that. White.
0:23:24 > 0:23:27So this was a beautiful demonstration of the fact
0:23:27 > 0:23:32that the primary lights - and notice the word light, not pigment -
0:23:32 > 0:23:36the primary lights are red, blue and green.
0:23:36 > 0:23:40And you can create any colour of light by suitable mixture
0:23:40 > 0:23:42of different proportions of these.
0:23:42 > 0:23:45What happens in paintings - pigments absorb light,
0:23:45 > 0:23:47whereas this is emitting light.
0:23:47 > 0:23:51So the upshot of all of this was that Maxwell was able to produce
0:23:51 > 0:23:54a rather beautiful colour triangle diagram
0:23:54 > 0:23:57which would indicate how you would create ANY colour
0:23:57 > 0:23:59by mixing the three primary colours.
0:24:02 > 0:24:06Maxwell's colour triangle allowed him to pick a specific colour
0:24:06 > 0:24:10and work out how much of each primary colour would be needed
0:24:10 > 0:24:11to reproduce it.
0:24:11 > 0:24:14This was made possible by his mathematical precision
0:24:14 > 0:24:16and systematic testing.
0:24:16 > 0:24:20Maxwell's work swept aside a sea of confusion.
0:24:20 > 0:24:24He vindicated Young's theory and demonstrated that we see
0:24:24 > 0:24:28colours in paints differently to the way we see colours in light.
0:24:29 > 0:24:34He established the primary colours for light as red, blue and green.
0:24:36 > 0:24:39He realised the receptors in our eyes were sensitive to those three.
0:24:42 > 0:24:45And that by mixing them, we perceived a vast range of colours.
0:24:48 > 0:24:50A few years later,
0:24:50 > 0:24:54he provided a stunning display that he was right.
0:24:59 > 0:25:03In 1861, Maxwell was invited to the Royal Institution in London
0:25:03 > 0:25:05to give a lecture on colour vision.
0:25:08 > 0:25:11But he didn't want to just talk about the principles,
0:25:11 > 0:25:14he wanted to demonstrate them to his audience.
0:25:20 > 0:25:23What he did would astonish them.
0:25:23 > 0:25:27Maxwell took three photographs of the same object.
0:25:27 > 0:25:29Each photo had a different filter on it -
0:25:29 > 0:25:33one was red, one was green and one was blue.
0:25:33 > 0:25:37That gave Maxwell three photographic plates that he could use
0:25:37 > 0:25:38to project an image with.
0:25:39 > 0:25:42When Maxwell projected the image from the red photograph
0:25:42 > 0:25:45onto the wall, he got a red picture.
0:25:47 > 0:25:49In an age when photography was black and white,
0:25:49 > 0:25:52this was INTERESTING but hardly revolutionary.
0:25:52 > 0:25:58But if you project all three images onto the wall at the exact same spot,
0:25:58 > 0:26:00something special happens.
0:26:06 > 0:26:08The audience were looking
0:26:08 > 0:26:10at the world's first colour photograph.
0:26:12 > 0:26:13They were stunned.
0:26:17 > 0:26:20Maxwell had chosen the perfect subject for his picture -
0:26:20 > 0:26:22a brightly coloured tartan ribbon.
0:26:24 > 0:26:27By layering red, green and blue images on top of each other,
0:26:27 > 0:26:31Maxwell established the possibility of creating colour photographs.
0:26:35 > 0:26:39150 years later, we use this method daily,
0:26:39 > 0:26:42because this three-colour principle is used in colour TV,
0:26:42 > 0:26:45computer screens, even mobile phones.
0:26:47 > 0:26:51The colours we see on our screens, however big or small,
0:26:51 > 0:26:54are created by carefully mixing the primary colours.
0:26:57 > 0:27:01Maxwell's work on colour provides the basis for our present
0:27:01 > 0:27:03understanding of colour vision.
0:27:04 > 0:27:05He even proposed an explanation
0:27:05 > 0:27:08for why some people were colour-blind.
0:27:08 > 0:27:11He said the receptors in their eyes were faulty,
0:27:11 > 0:27:14and that this radically altered how they perceived colour.
0:27:16 > 0:27:19Three weeks after his colour show, Maxwell was elected to the
0:27:19 > 0:27:23Royal Society for his work on Saturn's rings and on colour.
0:27:23 > 0:27:26He was now counted amongst the finest physicists in Britain.
0:27:27 > 0:27:28And he was 29.
0:27:32 > 0:27:34Despite his success,
0:27:34 > 0:27:37a year earlier Maxwell had found himself out of a job.
0:27:39 > 0:27:42When Marischal College merged with Aberdeen University,
0:27:42 > 0:27:45he had lost out to an older professor.
0:27:45 > 0:27:49Out of work, Maxwell and Katherine took a trip to the country,
0:27:49 > 0:27:51to somewhere very special to James.
0:27:54 > 0:27:59A quiet place hidden deep in Galloway, just west of Dumfries.
0:27:59 > 0:28:01A place called Glenlair.
0:28:01 > 0:28:03His family home.
0:28:05 > 0:28:07Maxwell's family had been established in the area
0:28:07 > 0:28:10for centuries, and Glenlair was a working estate.
0:28:13 > 0:28:17He was born in Edinburgh, but James had spent an idyllic childhood here.
0:28:17 > 0:28:20FAINT CHILDREN'S LAUGHTER
0:28:20 > 0:28:23Playing in the fields, swimming in the stream,
0:28:23 > 0:28:27running through the woods, nature truly was his playground.
0:28:27 > 0:28:32And that fostered a curiosity about how the natural world worked.
0:28:34 > 0:28:36For the first decade of his life,
0:28:36 > 0:28:38Maxwell was home-schooled by his mother.
0:28:38 > 0:28:42She encouraged his inquisitiveness.
0:28:42 > 0:28:46"Look up through nature," she said, "up to nature's god."
0:28:50 > 0:28:54Glenlair remained an important place to Maxwell throughout his life.
0:28:54 > 0:28:56It was somewhere that rooted him.
0:28:56 > 0:28:59A safe haven. A home.
0:29:01 > 0:29:04And the current owner of Glenlair knows just how that feels.
0:29:06 > 0:29:08So what was it like growing up at Glenlair?
0:29:08 > 0:29:13Well, I was a ten-year-old little boy when I came here,
0:29:13 > 0:29:16and I had the run of the place.
0:29:16 > 0:29:19My dad was quite an old chap and...
0:29:19 > 0:29:24he and my mother - and I was an only child, they were elderly -
0:29:24 > 0:29:26so they didn't really keep an eye on me.
0:29:26 > 0:29:30My childhood must have almost mirrored his,
0:29:30 > 0:29:31although I was slightly older.
0:29:31 > 0:29:34But I mean, a lot of his stuff's theoretical.
0:29:34 > 0:29:37It's kind of just thinking, difficult thinking.
0:29:37 > 0:29:39This seems a good place for theoretical thinkers.
0:29:39 > 0:29:44Yes, yes. And we have loads of professors who visit here.
0:29:44 > 0:29:47And nearly all of them stand here,
0:29:47 > 0:29:50and they look out at that view, and they say,
0:29:50 > 0:29:52"I know how he could do it."
0:29:52 > 0:29:55Because it just inspires you.
0:29:57 > 0:30:00So how do you encapsulate Maxwell? What is he for you?
0:30:00 > 0:30:03What do you think of him more than anything else?
0:30:04 > 0:30:07What appealed to me about Maxwell
0:30:07 > 0:30:10is how normal he was,
0:30:10 > 0:30:11as a boy,
0:30:11 > 0:30:14that he loved outside.
0:30:14 > 0:30:15He loved the open air.
0:30:15 > 0:30:18He loved all the creatures.
0:30:18 > 0:30:20And the gardens and the trees you see round here,
0:30:20 > 0:30:22thanks to Maxwell.
0:30:22 > 0:30:25But it's that emotional attachment that you feel to him?
0:30:25 > 0:30:29Yes, it's the way he loved it here, like I love it here.
0:30:29 > 0:30:33I've been offered lots and lots of money to sell this place,
0:30:33 > 0:30:35but there's no way they're going to get me out,
0:30:35 > 0:30:36except in a box.
0:30:40 > 0:30:44Like Duncan, Maxwell felt a strong connection to Glenlair.
0:30:45 > 0:30:48His proposal poem to Katherine had been about sharing their lives
0:30:48 > 0:30:51here - they'd even honeymooned in Glenlair.
0:30:51 > 0:30:56When they returned here in 1860, it wasn't just a holiday.
0:30:58 > 0:30:59On the death of his father,
0:30:59 > 0:31:02Maxwell had inherited over 1,000 acres of farmland.
0:31:04 > 0:31:07Dozens of working people relied on decisions he made.
0:31:08 > 0:31:12There were fields to sow, animals to tend, buildings to construct.
0:31:14 > 0:31:17He raised funds to build a church
0:31:17 > 0:31:19and was keen to improve local schooling.
0:31:21 > 0:31:24It was a responsibility he took seriously.
0:31:24 > 0:31:27And every summer, Maxwell and Katherine returned here
0:31:27 > 0:31:28to oversee the estate...
0:31:30 > 0:31:33..and recapture some of the childhood peace he'd found here.
0:31:35 > 0:31:37But Maxwell wouldn't stay at Glenlair.
0:31:37 > 0:31:40He wanted to be in the thick of scientific research,
0:31:40 > 0:31:42and that meant a university.
0:31:44 > 0:31:46After a rejection from Edinburgh,
0:31:46 > 0:31:50he accepted a position at King's College, London.
0:31:50 > 0:31:53Whilst there, he would produce his finest work
0:31:53 > 0:31:56and unravel one of the great mysteries of his age.
0:32:05 > 0:32:09Maxwell arrived in London at the end of 1860
0:32:09 > 0:32:11and assumed teaching duties immediately.
0:32:12 > 0:32:15While there, he focused on a subject that had
0:32:15 > 0:32:18captured his attention many years before.
0:32:20 > 0:32:22Ever since his early days at Cambridge, Maxwell had been
0:32:22 > 0:32:24interested in electricity,
0:32:24 > 0:32:27after it was suggested as an area to look at by a friend.
0:32:29 > 0:32:31That friend's advice was simple -
0:32:31 > 0:32:34if Maxwell wanted to learn something about electricity,
0:32:34 > 0:32:36he needed to know Michael Faraday.
0:32:39 > 0:32:42Faraday was a self-taught scientist who was revolutionising
0:32:42 > 0:32:45our understanding of electricity and magnetism.
0:32:49 > 0:32:51Maxwell's relationship with him
0:32:51 > 0:32:54was one of the most fruitful in 19th-century science.
0:32:58 > 0:33:01We'd known about electricity and magnetism since ancient times.
0:33:02 > 0:33:05Most people had experienced the power of electricity through
0:33:05 > 0:33:07terrifying lightning storms.
0:33:09 > 0:33:13And we'd used magnetism in ships' compasses for centuries.
0:33:17 > 0:33:20They were considered completely separate things
0:33:20 > 0:33:22for most of our history.
0:33:22 > 0:33:24But in the early 19th century,
0:33:24 > 0:33:27scientists like Faraday were beginning to see
0:33:27 > 0:33:29a mysterious connection between the two.
0:33:32 > 0:33:35Deep in the heart of the Royal Institution,
0:33:35 > 0:33:38Faraday conducted experiments to understand how they were linked.
0:33:43 > 0:33:46In one experiment, a copper wire carrying electricity
0:33:46 > 0:33:50somehow provoked a nearby compass to move.
0:33:52 > 0:33:55In another, Faraday tried to do the opposite...
0:33:56 > 0:33:59..use a magnet to generate electricity.
0:33:59 > 0:34:01Which led him to invent
0:34:01 > 0:34:04the electric generator, which this is
0:34:04 > 0:34:07an example where you have a permanent magnet and
0:34:07 > 0:34:10- a coiled wire.- So the wire's wrapped around this bit.
0:34:10 > 0:34:13The wire's wrapped around a cylinder, and you push and pull
0:34:13 > 0:34:16the magnet in and out of the cylinder
0:34:16 > 0:34:18- to generate an electric current. - I like the lights.
0:34:18 > 0:34:20What's the Christmas lights for, then?
0:34:20 > 0:34:23- Well, that's to show that electricity's passing.- Oh, OK.
0:34:25 > 0:34:28- Faraday did NOT use light-emitting diodes.- I think he should have done.
0:34:28 > 0:34:29That was his great mistake!
0:34:29 > 0:34:32And all electricity power stations throughout the world
0:34:32 > 0:34:35use this principle of generating electricity
0:34:35 > 0:34:38that Faraday discovered down here in 1831.
0:34:41 > 0:34:44Faraday had generated electricity simply by moving a magnet
0:34:44 > 0:34:46through a coiled wire -
0:34:46 > 0:34:49a discovery that would forever be associated with his name.
0:34:51 > 0:34:53But he was left with perplexing questions.
0:34:54 > 0:34:57There was no physical contact between the electric wire
0:34:57 > 0:34:59and the magnetic needle that moved
0:34:59 > 0:35:03nor between the moving magnet and the copper coil.
0:35:04 > 0:35:07They were affecting each other through seemingly thin air.
0:35:09 > 0:35:11But how could that be?
0:35:11 > 0:35:13Now, what Faraday thought was happening was that there were
0:35:13 > 0:35:19lines of force coming out of the end of the magnet,
0:35:19 > 0:35:24which were then cutting the wire within the coil
0:35:24 > 0:35:28to move electricity around the coil.
0:35:28 > 0:35:31The idea of mysterious lines coming out of the magnet to generate
0:35:31 > 0:35:34electricity may have seemed outlandish,
0:35:34 > 0:35:38but Faraday had a simple experiment that could prove their existence.
0:35:39 > 0:35:42So he took a very powerful, permanent magnet.
0:35:43 > 0:35:45Placed some paper...
0:35:46 > 0:35:47..on it.
0:35:49 > 0:35:53Sprinkled iron filings over it.
0:35:56 > 0:36:00Just to represent the lines of force...
0:36:00 > 0:36:04- It never fails to impress, that, does it?- ..of the magnet.
0:36:04 > 0:36:07- And you can see the sort of three dimensional structure.- Yeah, yeah.
0:36:07 > 0:36:10- So these are coming up here and swinging around...- That's right.
0:36:10 > 0:36:12..and then coming down into this bit here.
0:36:12 > 0:36:17And Faraday sort of made permanent examples of this and sent them round
0:36:17 > 0:36:20to all his mates in Europe, to show that space had structure
0:36:20 > 0:36:23as a very strong argument for his field theory.
0:36:23 > 0:36:26So Faraday thought there was an invisible force field at work here?
0:36:26 > 0:36:32Well, literally a field. Faraday brings the world field
0:36:32 > 0:36:34into science. And it's invisible, as you say.
0:36:34 > 0:36:37So this is why this is just a representation that shows
0:36:37 > 0:36:42- the existence of those invisible lines.- Yes, absolutely.
0:36:45 > 0:36:48Faraday's iron filings experiment revealed
0:36:48 > 0:36:52the existence of an invisible field stretching out into thin air.
0:36:54 > 0:36:56These fields, he thought,
0:36:56 > 0:36:59were responsible for the experimental results he'd seen.
0:37:02 > 0:37:04Despite having physical proof,
0:37:04 > 0:37:08Faraday lacked a mathematical description of how the field
0:37:08 > 0:37:11was generated or why it affected things around it.
0:37:14 > 0:37:17Without a mathematical proof,
0:37:17 > 0:37:22many 19th-century scientists dismissed the theory as speculative.
0:37:22 > 0:37:25But Maxwell had followed Faraday's work for years...
0:37:25 > 0:37:27and set out to prove him right.
0:37:32 > 0:37:34Maxwell had plenty of time to mull over the problem.
0:37:42 > 0:37:44The walk from his Kensington home to King's College
0:37:44 > 0:37:47was an eight-mile round trip every day.
0:37:48 > 0:37:51And during the walk, he allowed his mind to wander.
0:37:52 > 0:37:55On those walks - and at work - he had company.
0:37:57 > 0:37:59Apparently, Maxwell always had a dog.
0:37:59 > 0:38:02And he always called it the same name!
0:38:02 > 0:38:05From childhood onwards, every dog was called Toby.
0:38:05 > 0:38:09And Toby - whichever one it was - rarely left his side.
0:38:10 > 0:38:14Toby was a constant companion at home and in the lab.
0:38:14 > 0:38:16It's a sign of Maxwell's eccentricity
0:38:16 > 0:38:18that he would talk to Toby.
0:38:18 > 0:38:19He said he liked his company.
0:38:21 > 0:38:25During his walks to and from work, Maxwell - and perhaps Toby -
0:38:25 > 0:38:28brooded over the mysterious relationship between electricity
0:38:28 > 0:38:30and magnetism.
0:38:35 > 0:38:39His aim was to provide a mathematical explanation
0:38:39 > 0:38:40for the link between the two.
0:38:43 > 0:38:45After years of thinking -
0:38:45 > 0:38:47and who knows how many miles walking -
0:38:47 > 0:38:49he came up with a set of equations
0:38:49 > 0:38:53that described the relationship between electricity and magnetism.
0:38:54 > 0:38:58Equations that would change our lives forever.
0:38:58 > 0:39:01Sorry, Frank, but this is just gobbledygook to me.
0:39:01 > 0:39:03I'm just looking at it trying to make sense of it.
0:39:03 > 0:39:06Well, it's not much easier for me. I mean...
0:39:06 > 0:39:08That's what he wrote first of all. And looking at these,
0:39:08 > 0:39:11they probably mean little more to me than to you.
0:39:11 > 0:39:12But 20 years later,
0:39:12 > 0:39:15they were written in a simpler form which is the way that this...
0:39:15 > 0:39:18- This form here. - That looks more manageable.
0:39:18 > 0:39:21But it still looks a bit confusing. Could you take us through it, then?
0:39:21 > 0:39:25Right. Well, the first one says that if you've got an electric charge,
0:39:25 > 0:39:28it spreads an electric field out all over space.
0:39:29 > 0:39:32Just like his work on Saturn's rings,
0:39:32 > 0:39:35each equation is a mathematical description of something
0:39:35 > 0:39:37observed in the real world.
0:39:39 > 0:39:42So the first equation described how a static electric charge
0:39:42 > 0:39:44generates an electric field.
0:39:48 > 0:39:53And the second, that magnetic poles always come in pairs.
0:39:54 > 0:39:58The third equation describes how a changing magnetic field
0:39:58 > 0:40:00generates an electric field.
0:40:02 > 0:40:04And the fourth equation,
0:40:04 > 0:40:08that an electric current surrounds itself with a magnetic field.
0:40:08 > 0:40:12But Maxwell realised there was something missing.
0:40:12 > 0:40:17Maxwell's genius was to realise that each of these equations is fine
0:40:17 > 0:40:19- until you put them together.- Mm-hm.
0:40:19 > 0:40:21And then he realised something was missing,
0:40:21 > 0:40:23and it was in this final equation.
0:40:23 > 0:40:26He said, "There has to be another term."
0:40:30 > 0:40:33And what this extra piece says
0:40:33 > 0:40:37is if an electric field is changing,
0:40:37 > 0:40:39it will surround itself with a magnetic field.
0:40:39 > 0:40:42- Right.- Which is like the sort of mirror of this equation,
0:40:42 > 0:40:45which says if a magnetic field is changing,
0:40:45 > 0:40:48it will surround itself with an electric field.
0:40:48 > 0:40:51So, just take these two together and just think about it for a second.
0:40:51 > 0:40:53If I've got a magnetic field changing,
0:40:53 > 0:40:55it surrounds itself with an electric.
0:40:55 > 0:40:58If the electric is changing, it surrounds itself with
0:40:58 > 0:41:00a magnetic. And if that is changing,
0:41:00 > 0:41:02it will surround itself again with an electric, and so on.
0:41:02 > 0:41:05Faraday to Maxwell, electric to magnetic back and forth,
0:41:05 > 0:41:08- back and forth.- So there's a coupling, basically, between the two.
0:41:12 > 0:41:16Maxwell's equations were saying that electric and magnetic fields
0:41:16 > 0:41:17were inextricably linked.
0:41:19 > 0:41:21Changes in one created changes in the other.
0:41:25 > 0:41:28It helped explain so much.
0:41:28 > 0:41:30When Faraday moved his magnet,
0:41:30 > 0:41:33he'd changed the position of the magnetic field,
0:41:33 > 0:41:35and this triggered an electric field
0:41:35 > 0:41:38which caused electricity to flow through the wire.
0:41:39 > 0:41:42And when electricity passed through a wire,
0:41:42 > 0:41:44it wrapped a magnetic field around it,
0:41:44 > 0:41:46causing the compass needle to move.
0:41:50 > 0:41:54Using pure maths, Maxwell had unified electricity
0:41:54 > 0:41:56and magnetism
0:41:56 > 0:41:59and shown they were two aspects of the same thing -
0:41:59 > 0:42:02a single electromagnetic field.
0:42:05 > 0:42:08This alone would have guaranteed Maxwell's entry
0:42:08 > 0:42:10to the scientists hall of fame.
0:42:10 > 0:42:13He could have rested on his laurels.
0:42:13 > 0:42:16But whether it was his natural curiosity or the long walks
0:42:16 > 0:42:19with Toby, he didn't stop there.
0:42:19 > 0:42:23He used his equations to test another of Faraday's ideas.
0:42:25 > 0:42:27Faraday had guessed that under certain circumstances,
0:42:27 > 0:42:31the electric and magnetic field lines could be disturbed by waves
0:42:31 > 0:42:33travelling along them -
0:42:33 > 0:42:36almost like ripples on the surface of water.
0:42:42 > 0:42:45Maxwell used his equations to show that the fields
0:42:45 > 0:42:47could fluctuate in time with each other
0:42:47 > 0:42:53and cause what Maxwell called an electromagnetic wave.
0:42:53 > 0:42:55He could even measure the speed of the wave.
0:42:55 > 0:43:00This says the electromagnetic wave travels through space.
0:43:00 > 0:43:02And buried in here,
0:43:02 > 0:43:06he was able to extract the speed that the wave travels.
0:43:06 > 0:43:09And when he put the numbers in, from things that Faraday and others
0:43:09 > 0:43:13had already measured, he worked out the speed and it came out as
0:43:13 > 0:43:16a phenomenal 300,000 kilometres every second, roughly.
0:43:17 > 0:43:22And that, I think, is the moment of discovery because he knew
0:43:22 > 0:43:24that people had measured the speed of light,
0:43:24 > 0:43:26which was 300,000 kilometres every second.
0:43:26 > 0:43:28Now, at this moment you think,
0:43:28 > 0:43:31- is this a coincidence or are these equations telling me something? - Yeah.
0:43:31 > 0:43:33And, of course, they're telling you something,
0:43:33 > 0:43:37and what the message is - light is an electromagnetic wave.
0:43:39 > 0:43:42This was a stunning conclusion.
0:43:45 > 0:43:48Maxwell had explained what light itself was.
0:43:49 > 0:43:53At the same time, he'd introduced something new to science -
0:43:53 > 0:43:58electromagnetic waves - and they were destined to change our planet.
0:44:01 > 0:44:03The problem was he hadn't physically demonstrated
0:44:03 > 0:44:06the existence of these waves.
0:44:06 > 0:44:08It was all in the maths.
0:44:08 > 0:44:11Physical proof would have to come later.
0:44:12 > 0:44:15His equations were an astonishing piece of work,
0:44:15 > 0:44:17packed with radical ideas.
0:44:18 > 0:44:21Maxwell gave us a unified theory of electricity and magnetism,
0:44:21 > 0:44:26he solved the mystery of what light was and he predicted the existence
0:44:26 > 0:44:30of these invisible fields that would directly affect our life.
0:44:30 > 0:44:34That's difficult enough to grasp for a 21st-century scientist,
0:44:34 > 0:44:36but what on earth did the Victorians think?
0:44:39 > 0:44:42The fact is Maxwell was asking a lot from his peers.
0:44:42 > 0:44:45Invisible fields, undetected waves,
0:44:45 > 0:44:47dense maths -
0:44:47 > 0:44:51it was all a bit much for 19th-century scientists.
0:44:51 > 0:44:55Ironically, Maxwell found himself in a similar position to Faraday -
0:44:55 > 0:44:57surrounded by sceptical colleagues
0:44:57 > 0:45:01and lacking the proof to vindicate his theory.
0:45:01 > 0:45:04But a jubilant Maxwell was undeterred -
0:45:04 > 0:45:06he wrote an excited letter to his cousin.
0:45:07 > 0:45:09"I also have a paper afloat, with
0:45:09 > 0:45:12"an electromagnetic theory of light,
0:45:12 > 0:45:16"which until I'm convinced to the contrary, I hold to be great guns."
0:45:18 > 0:45:19The guns may have fired,
0:45:19 > 0:45:22but it would be a while before they would be heard.
0:45:22 > 0:45:25It took more than 20 years before a German scientist called
0:45:25 > 0:45:30Heinrich Hertz found physical proof for electromagnetic waves.
0:45:30 > 0:45:33When he was asked what practical use the wave had,
0:45:33 > 0:45:35he replied, "It's of no use whatsoever.
0:45:35 > 0:45:39"This is just an experiment that proves Maestro Maxwell was right."
0:45:44 > 0:45:48How wrong he was, because Hertz had discovered radio waves.
0:45:49 > 0:45:52Marconi invented the radio, and since then, we've been
0:45:52 > 0:45:56using them to spread radio and television all over the planet.
0:45:56 > 0:45:59But this was just the first in a long list of discoveries.
0:45:59 > 0:46:03# Happy days are here again... #
0:46:03 > 0:46:07Using higher frequency radio waves, we developed radar,
0:46:07 > 0:46:12which now gets used in everything from aviation to geology.
0:46:12 > 0:46:15Microwaves were discovered, which we use in cooking
0:46:15 > 0:46:16and when we use a mobile phone.
0:46:16 > 0:46:19Infrared is used in thermal imaging
0:46:19 > 0:46:22and in most TV remote controls.
0:46:22 > 0:46:24Ultraviolet is used in fluorescent lamps,
0:46:24 > 0:46:27security marking and medical research.
0:46:27 > 0:46:31X-rays have provided us with a valuable medical tool,
0:46:31 > 0:46:33but more recently in security.
0:46:33 > 0:46:35And gamma rays have been used to
0:46:35 > 0:46:39detect and treat cancer, and even to sterilise the food we eat.
0:46:41 > 0:46:42All these things are connected.
0:46:44 > 0:46:46Maxwell had shown that light and the colours we see
0:46:46 > 0:46:49are electromagnetic waves.
0:46:49 > 0:46:52But he predicted there would be more.
0:46:52 > 0:46:56Today, we know that visible light is just a tiny sliver
0:46:56 > 0:46:58of a broad spectrum of electromagnetic waves.
0:47:00 > 0:47:01And by understanding
0:47:01 > 0:47:02and exploiting them,
0:47:02 > 0:47:05we've revolutionised our world,
0:47:05 > 0:47:06all thanks to equations
0:47:06 > 0:47:09Maxwell published 150 years ago.
0:47:14 > 0:47:17That was all part of a future that Maxwell wouldn't see.
0:47:19 > 0:47:23When he first published, people didn't understand him.
0:47:23 > 0:47:28You know, back in 1865, there was no sign, no evidence of these mysterious
0:47:28 > 0:47:30electromagnetic waves.
0:47:30 > 0:47:33Maxwell was asking people to believe that these waves could pass
0:47:33 > 0:47:37through empty space and affect things at a distance.
0:47:37 > 0:47:39It was just too much to ask.
0:47:39 > 0:47:44His equations were initially met with a bewildered silence.
0:47:44 > 0:47:4619th-century scientists were used to
0:47:46 > 0:47:49thinking of the world in mechanical terms -
0:47:49 > 0:47:53physically tangible objects that could be touched, measured and felt.
0:47:54 > 0:47:57Flying in the face of that was Maxwell's theory -
0:47:57 > 0:47:59based on dense mathematics,
0:47:59 > 0:48:02invisible fields and undetected waves.
0:48:03 > 0:48:05Many thought Maxwell's theory
0:48:05 > 0:48:08was a kind of abstract mathematical speculation.
0:48:08 > 0:48:12That he had strayed too far from physical reality.
0:48:12 > 0:48:16That he was, in essence, away with the fairies.
0:48:16 > 0:48:19Maxwell became convinced that he had to develop his theory
0:48:19 > 0:48:21of magnetism and electricity.
0:48:21 > 0:48:23Not long after that publication,
0:48:23 > 0:48:25he decided to pursue his own interests
0:48:25 > 0:48:28and resigned his post at King's.
0:48:28 > 0:48:29He was going home.
0:48:37 > 0:48:41After the lukewarm reaction to his 1865 publication,
0:48:41 > 0:48:44the comfort of Glenlair was welcome.
0:48:44 > 0:48:48Ever industrious, Maxwell produced papers on thermodynamics
0:48:48 > 0:48:50and even topology.
0:48:50 > 0:48:54But always he returned to his electromagnetic theory,
0:48:54 > 0:48:55slowly refining it.
0:48:57 > 0:49:02After six years in the wilderness, Cambridge University approached him.
0:49:02 > 0:49:07They wanted someone to plan and run a lab in Experimental Physics.
0:49:07 > 0:49:10Despite all his achievements, Maxwell was third in line,
0:49:10 > 0:49:13after two other candidates had rejected the offer.
0:49:19 > 0:49:22In 1871, he left Glenlair for Cambridge,
0:49:22 > 0:49:26where he designed and built the Cavendish Laboratory,
0:49:26 > 0:49:29which would be responsible for discoveries that shaped physics
0:49:29 > 0:49:30in the 20th century.
0:49:33 > 0:49:34And as its first director,
0:49:34 > 0:49:39his open-minded approach set the tone for subsequent generations.
0:49:40 > 0:49:41"I never try to dissuade
0:49:41 > 0:49:43"a man from trying an experiment.
0:49:43 > 0:49:45"If he does not find out
0:49:45 > 0:49:46"what he wants,
0:49:46 > 0:49:48"he may find out something else."
0:49:52 > 0:49:55The Cavendish Lab would become a phenomenal success.
0:49:58 > 0:50:01It's within these walls that we discovered the electron
0:50:01 > 0:50:02and later on the neutron.
0:50:04 > 0:50:08Watson and Crick were working here when, in 1953,
0:50:08 > 0:50:11X-rays were used to show the structure of DNA.
0:50:14 > 0:50:18The Cavendish is now widely regarded as a centre of excellence,
0:50:18 > 0:50:21and it's produced 29 Nobel Prize winners to date.
0:50:25 > 0:50:28But every summer, Maxwell returned to Glenlair,
0:50:28 > 0:50:30patiently working out the full implications
0:50:30 > 0:50:33of his electromagnetic theory of light.
0:50:42 > 0:50:45In 1873, Maxwell released
0:50:45 > 0:50:49a dynamical theory of electricity and magnetism.
0:50:52 > 0:50:55The intervening years had allowed his colleagues time to digest
0:50:55 > 0:50:59his theory, and it was starting to gain traction.
0:50:59 > 0:51:02But he wouldn't live to see it vindicated.
0:51:03 > 0:51:06When guests were visiting Glenlair in 1879,
0:51:06 > 0:51:10Maxwell found he could barely walk down to the river, such was the pain.
0:51:11 > 0:51:13The pain was in his stomach.
0:51:13 > 0:51:14In October of that year,
0:51:14 > 0:51:17he was diagnosed with abdominal cancer,
0:51:17 > 0:51:18given a month to live.
0:51:28 > 0:51:31Maxwell was just 48 when he received the news.
0:51:33 > 0:51:37He knew his mother had died at the same age, from the same disease.
0:51:44 > 0:51:46Nevertheless, he accepted his fate
0:51:46 > 0:51:49with the calm stoicism that had defined his life.
0:51:52 > 0:51:55Katherine nursed him as best she could.
0:51:55 > 0:51:58It's said that on his deathbed, Maxwell breathed deeply,
0:51:58 > 0:52:02and with a long look at his wife, passed away.
0:52:10 > 0:52:14James Clerk Maxwell died in November 1879.
0:52:15 > 0:52:17He was buried in Parton Kirk,
0:52:17 > 0:52:21his childhood church, just a few miles from his beloved Glenlair.
0:52:32 > 0:52:35He lies in a modest grave next to his parents.
0:52:35 > 0:52:39And seven years later, Katherine would be buried next to him.
0:52:43 > 0:52:45Apart from a plaque outside the cemetery,
0:52:45 > 0:52:47there's nothing to mark this grave as different
0:52:47 > 0:52:49from any of the others.
0:52:49 > 0:52:52There's no list of grand achievements.
0:52:52 > 0:52:56It's just simple and modest, like the man himself.
0:53:01 > 0:53:04A visitor could be forgiven for passing the grave
0:53:04 > 0:53:06without a second glance.
0:53:06 > 0:53:09But for some, this is a special place.
0:53:14 > 0:53:17There is a story that is told around Parton Kirk.
0:53:17 > 0:53:20Shortly after the fall of the Berlin Wall, two buses arrived,
0:53:20 > 0:53:23and people filed into the graveyard.
0:53:24 > 0:53:26A curious local asked who they were.
0:53:26 > 0:53:30They were, they said, Russian scientists who had travelled
0:53:30 > 0:53:33to visit the grave of Scotland's Einstein.
0:53:35 > 0:53:39You know, Maxwell died at a relatively young age, 48,
0:53:39 > 0:53:44which even by the standards of his day, was an untimely death.
0:53:44 > 0:53:45And you just wonder,
0:53:45 > 0:53:48given the achievements that he had in his lifetime,
0:53:48 > 0:53:53what he would have conjured up if he'd lived until he was 60 or 70.
0:53:54 > 0:53:57Maxwell may not have been fully appreciated in his time,
0:53:57 > 0:54:00but in the decades following his death, scientists started
0:54:00 > 0:54:02to recognise his genius.
0:54:09 > 0:54:11Eight years after Maxwell's death,
0:54:11 > 0:54:13Heinrich Hertz discovered radio waves,
0:54:13 > 0:54:17proving beyond doubt the existence of electromagnetic waves.
0:54:22 > 0:54:24The rest, as they say, is history.
0:54:26 > 0:54:29Over a century later, these waves have changed our planet
0:54:29 > 0:54:32and are part of our everyday lives.
0:54:36 > 0:54:39But focusing on the technological results of his work
0:54:39 > 0:54:42diminishes its importance,
0:54:42 > 0:54:45because he changed the way we understand reality itself.
0:54:45 > 0:54:47Before the work
0:54:47 > 0:54:49of Maxwell, and Faraday just before him,
0:54:49 > 0:54:52the experiments, we understood the world in terms
0:54:52 > 0:54:53of springs and cogs,
0:54:53 > 0:54:55a machine-like world.
0:54:55 > 0:54:59And that machine-like world was pretty primitive.
0:54:59 > 0:55:04What Maxwell's work showed is that the way that we understand
0:55:04 > 0:55:08the interaction between material bodies is via
0:55:08 > 0:55:11this idea of a field, not the sort of field we're standing in.
0:55:11 > 0:55:15- Not a green field?- Not a green field but something that penetrates
0:55:15 > 0:55:20space and which really governs the way that the world behaves.
0:55:23 > 0:55:26Maxwell helped overthrow the mechanical model of the universe
0:55:26 > 0:55:29that physicists had held since Newton
0:55:29 > 0:55:31and issued in a new era.
0:55:33 > 0:55:36We now think of all the forces in the universe interacting
0:55:36 > 0:55:40through fields rather than direct physical contact.
0:55:42 > 0:55:46This was a crucial shift in our understanding,
0:55:46 > 0:55:50prompting Einstein to say, "One scientific epoch ended
0:55:50 > 0:55:53"and another began with James Clerk Maxwell."
0:55:57 > 0:56:01Which is, perhaps, why he's still revered by scientists today.
0:56:08 > 0:56:12This meeting we're having here in Edinburgh today is very special.
0:56:12 > 0:56:13We're celebrating
0:56:13 > 0:56:16the 150th anniversary of Maxwell's
0:56:16 > 0:56:20publication of his equations of electromagnetism.
0:56:21 > 0:56:25Some of Britain's finest scientists gather at an event to remember
0:56:25 > 0:56:28the life and work of James Clerk Maxwell.
0:56:29 > 0:56:31Maxwell is all around us.
0:56:32 > 0:56:34Every single piece of technology
0:56:34 > 0:56:36that is around us today -
0:56:36 > 0:56:37computing, fibre optics,
0:56:37 > 0:56:41cameras, mobile phones, everything depends
0:56:41 > 0:56:44on extensions of those Maxwell's equations.
0:56:46 > 0:56:49Without those, we wouldn't be where we are today.
0:56:49 > 0:56:53Even the internet doesn't exist without them.
0:56:53 > 0:56:56Maxwell changed the way we think forever.
0:57:00 > 0:57:03'You can't overestimate his contribution,
0:57:03 > 0:57:06'his influence on everything,
0:57:06 > 0:57:08'both practical and theoretical.'
0:57:08 > 0:57:12He is the most remarkable Scot, intellectually,
0:57:12 > 0:57:14that has ever arisen.
0:57:14 > 0:57:15No question about it.
0:57:17 > 0:57:21In terms of the sequence of the great men of physics,
0:57:21 > 0:57:24starting with Galileo and Newton,
0:57:24 > 0:57:26then comes Maxwell
0:57:26 > 0:57:27and then Einstein,
0:57:27 > 0:57:30who said that
0:57:30 > 0:57:35Maxwell was the greatest physicist after Newton.
0:57:35 > 0:57:38It's wonderful to be sitting in the audience of a meeting
0:57:38 > 0:57:42surrounded by Nobel Prize winners, the great and the good.
0:57:42 > 0:57:47There's a sense of shared excitement that you...
0:57:47 > 0:57:51This unapologetic geekiness that however much...
0:57:51 > 0:57:53You know, people like Peter Higgs
0:57:53 > 0:57:57and Nobel Prize winners, we are still in awe
0:57:57 > 0:57:58of this giant of physics.
0:58:00 > 0:58:04And having got to know the man, I can understand why.
0:58:05 > 0:58:09I can't blame people for not knowing about James Clerk Maxwell -
0:58:09 > 0:58:11this is difficult stuff!
0:58:11 > 0:58:14I just think that, given the breadth of his discoveries
0:58:14 > 0:58:16and the sheer impact they've had, it's a travesty
0:58:16 > 0:58:19that Maxwell's name's not up there with Newton and Einstein
0:58:19 > 0:58:21as one of the greats.
0:58:21 > 0:58:26Maxwell is Scotland's Einstein, and we should remember him as such.