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00:00Our planet is filled with signals invisible to the naked eye
00:24But space itself can be just as noisy
00:36This is Cambridge University's radio telescope observatory
00:42It's used to examine the far reaches of space
00:47To answer questions about the very origin of our universe
00:53These magnificent dishes are detecting signals from radiation left over from the Big Bang
00:59But they're not optical telescopes in the sense of looking through an eyepiece and seeing a planet or a star
01:05These dishes are detecting radio waves
01:11These telescopes allow us to see the unseen
01:15Extraordinary images like these are made possible thanks to radio waves
01:27Microwaves
01:29And gamma rays
01:31The thing is all these waves are connected
01:35They're all different types of something we call electromagnetic radiation
01:39Visible light, the light that you and I can see
01:41It's just a tiny portion of this broader spectrum of waves
01:45And we use waves to probe the outer reaches of our universe
01:49But we use them for so much more
01:53In fact, electromagnetic waves are at the heart of modern technology
01:59We use them every day in everything from medicine to communications
02:03There it is
02:05There it is
02:07Our mastery of these waves was made possible when one man published a set of equations in 1865
02:17A man called James Clark Maxwell
02:21His name's barely known to the public
02:23And yet he's probably the finest scientist Scotland's ever produced
02:27And 150 years after his greatest discovery
02:31I'm setting out to explore the story of the man and his work
02:43Excuse me, can I ask you a question?
02:45Do you recognise this person?
02:47No?
02:48Do you know who he is?
02:49Alexander Graham Bell
02:51No idea
02:52He looks like a banker, an economist maybe
02:55James Clark Maxwell
02:59Still no idea
03:00Still no idea
03:01James Clark Maxwell
03:03Never heard of him
03:05Albert Einstein, he's not right
03:07You're so close
03:08James Clark Maxwell
03:10Name ring a bell?
03:11Maxwell's equations
03:13Maxwell's equations
03:14I don't know what they're about
03:15But I've heard of them
03:17Right, you do physics?
03:18I do physics
03:19James Clark Maxwell then, let's use your test
03:21I just failed physics
03:23That's his statue
03:25Is it actually?
03:26That's his statue
03:27Oh
03:28You probably pass that quite regularly
03:30Quite regularly, so it's quite an embarrassment to say
03:32No but no one, I've been asking everyone here
03:34James Clark Maxwell
03:37No one knows who he is?
03:41Any ideas?
03:42This is the statue of James Clark Maxwell
03:47And yet virtually no one around here knows who he is
03:50But I don't blame them because Maxwell seems to have slipped through the cracks of history
03:55At least as far as the public is concerned
03:57So who was he?
04:02James Clark Maxwell was a 19th century Scottish scientist
04:06He used this genius to work across a wide range of subjects
04:12Astronomy, physiology, colour, optics, thermodynamics, electricity and magnetism
04:21He touched on all of these
04:23And changed many of them beyond recognition
04:27He caused a revolution in physics
04:29And gave us the laws for one of the four fundamental forces of the universe
04:36Einstein kept a picture of Maxwell on the wall of his study
04:40And one said
04:41I stand on the shoulders of James Clark Maxwell
04:46It's a sentiment shared by many physicists today
04:49Maxwell did for electricity and magnetism
04:51What Isaac Newton did for gravity
04:53He's one of my great heroes
04:54He's one of my great heroes
04:55He's one of the greatest scientists we're ever ever going to encounter
04:59He's on the par with Einstein
05:01With Newton
05:02With Archimedes
05:03He transformed our way in which we understand the world
05:07He's probably the greatest scientist Scotland's ever produced
05:10And we're still living in the shadow of his achievements
05:12And yet no one knows who he is
05:15Even me, a Scot and a scientist
05:17Just got this vague notion of what he did
05:20But I want to change that
05:21I want to rediscover James Clark Maxwell
05:33Born in Edinburgh in 1831
05:36Maxwell was the only child in a landowning family from Galloway
05:43The scientific revolution of the previous centuries
05:46Was changing our view of the world
05:47But modern science was still in its infancy
05:55The 19th century would see ground-breaking discoveries
06:02And Maxwell would be at the heart of it
06:04Compelled by a probing mind
06:05His inquisitive nature was obvious, even in childhood
06:06When he was a boy the zoetrope was a new invention
06:19And the young Maxwell loved him
06:21And the young Maxwell loved him
06:22He was kind of hypnotic
06:25In a sense these are the forerunners of movies and television
06:28You can imagine Kenton in the 19th century just being mesmerised by them
06:29Most of them would have been happy just to sit back and enjoy the show
06:31But Maxwell wanted to know how they worked
06:32Maxwell wanted to know how they worked
06:33The moving figures in the 19th century
06:34And the young Maxwell loved him
06:35And the young Maxwell loved him
06:37He was kind of hypnotic
06:39In a sense these are the forerunners of movies and television
06:44And you can imagine Kenton in the 19th century just being mesmerised by them
06:49Most of them would have been happy just to sit back and enjoy the show
06:52But Maxwell wanted to know how they worked
06:54The moving figures are a trick of the eye
07:04Stop the drums spinning
07:05And you can see the simple sketches that help create the moving image
07:12This simple illusion captivated Maxwell
07:15As a child he would build his own zoetrope strips
07:17To entertain his family
07:19And to understand how they worked
07:21This desire to understand the world around him
07:26Continued into adulthood
07:30Aged as 14
07:32He produced a paper on geometric shapes
07:35That showed such mathematical ingenuity it was published
07:39And then read at the Royal Society of Edinburgh
07:43By an established professor as James was deemed too young
07:47As a teenager he conducted homemade experiments
07:51Into light and colour
07:55And by the time he arrived at Cambridge University
07:58Aged 19
08:00He'd already published three mathematical papers
08:06From the age of 14
08:08Maxwell had been using mathematics to explain how the world worked
08:12It was a talent he would rely on for many of his discoveries
08:16And it was key to establishing his scientific reputation
08:19Because while still in his twenties
08:22He used maths to solve a riddle that had puzzled scientists for centuries
08:35Saturn's rings
08:37A vivid band surrounding one of our solar system's giant planets
08:40We've become accustomed to their beauty
08:42But in previous centuries they were an enigma
08:48Galileo first drew them in 1610
08:52And they immediately fascinated astronomers
08:55Sometimes the rings were hidden
08:57At other times clearly visible in the night sky
09:00By the mid-19th century we knew the rings were composed of at least two vast concentric circles
09:10Over 250,000 kilometres in diameter
09:14But what were the rings made of?
09:19And why did they stay in place?
09:20In 1855 the Cambridge College published an open competition to answer those very questions
09:27But the answer would have to be accompanied by a full mathematical proof
09:32Maxwell's response would earn his stripes as one of Britain's top physicists
09:36There were three possible explanations for Saturn's rings
09:44One possibility was that the rings were solid rock or ice
09:48Another that they were entirely fluid
09:51A third explanation said the rings were made up of lots of individual particles that circled Saturn
09:58As the rings were over a billion kilometres away
10:02Proving which explanation was right seemed impossible
10:06So how did Maxwell go about disentangling those options?
10:11Well with great difficulty
10:13But of course what's really striking, what's very impressive
10:16Is that he did it using pure maths
10:18And you wouldn't perhaps instantly think that this was a problem you could tackle
10:22That way you think well the way to do it is to just build a big telescope and have a look
10:25But the mathematics that Maxwell brought to bear on this allowed him to look at these three cases
10:32And to basically decide which one of them was the correct answer
10:36So if we take first of all the case of a completely solid ring
10:40There's a particular mathematical equation that describes that case
10:45The distance from the centre of the planet to the centre of the rings
10:49That's this big R here
10:50The maths is incredibly complicated and as a geologist I'm a bit out of my depth
11:00But I understand the basic point
11:03Maxwell reduced the physical world to mathematical symbols
11:07And then used maths to predict what was happening around Saturn
11:11Maxwell said that a solid ring was possible
11:16But only if most of the material was bunched together on one side of the planet
11:21And of course if you look through a telescope it doesn't look like that
11:25So that model was discarded
11:27Back to the drawing board
11:29Maxwell then assumed that the rings were fluid
11:32And came up with an equation to describe how that might work
11:35Off he goes with his complicated mathematics
11:37He found that if the rings were fluid physical forces acting on them would eventually break them up into lumps
11:45So he discounted this possibility
11:47And that leaves the third possibility
11:51Which is that the rings consist of a very large number of independently moving particles
11:56Particles that are all orbiting Saturn on their own
11:59And 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
12:09And sure enough this seemed to work
12:11So it wasn't just that he'd shown that the other two possibilities were wrong
12:15But that this third possibility did actually work as well
12:18Well I find staggering is just the notion that you can just use numbers to predict something
12:24You've got absolutely no knowledge about it directly
12:27I think for me that's almost a watershed moment in how we do physics
12:32Because you know it laid the foundations for really how we do physics today
12:36Because there's many examples of everything from say the Higgs boson
12:40To studying distant galaxies where you can make theoretical predictions
12:43And it might be years or decades or even centuries before you can fully test those predictions
12:49But hey it works
12:53We're just zooming in on the ring plane
12:58That's great isn't it?
13:00Yeah, amazing
13:04Here they are
13:06We're in the ring
13:08Look at that
13:10What do you think Maxwell would have given to have seen this?
13:11Yeah
13:12Oh I'm sure he would have loved it
13:16Almost 130 years after Maxwell's prediction
13:19We captured images that proved his theory beyond doubt
13:26In 1977 an ambitious NASA launched the Voyager probe
13:31And three years later it sent home sensational images of Saturn's rings
13:37Saturn's rings
13:39In 2009 the Cassini probe confirmed those findings
13:43Saturn's rings were made of millions of icy rocks
13:47In recognition of his work, a division between the rings
13:53Known as the Maxwell Gap
13:55But his maths has been applied beyond Saturn
13:58This image from the Taurus constellation shows a young sun at the heart of a huge cloud of dust and rocks
14:12As the cloud circles a star, dark bands reveal areas where rocks are clumping together to form planets
14:19We're witnessing the birth of a solar system
14:23And the maths we use to understand this process is the same as Maxwell's work on Saturn's rings
14:32Maths is a powerful tool that physicists use to understand and predict the universe
14:37And Maxwell was a master of it
14:39In solving the problems of Saturn's rings Maxwell had put a marker down
14:43He wanted the scientific establishment to take him seriously
14:45And they did
14:47When Maxwell delivered his paper it was the only one that the Cambridge Committee received
15:01No one else came up with an explanation
15:03Overnight Maxwell became known as one of Britain's great theoretical physicists
15:08This wasn't a surprise to those who knew him
15:13Because his teenage precociousness had been followed by ground-breaking experiments as an undergraduate
15:20So perhaps it's no wonder that Maxwell was made Professor here at Aberdeens Marshall College at the tender age of 25
15:27His star was on the rise
15:30His career may have been taking off, but this was a difficult time for Maxwell
15:36An only child, he'd been extremely close to his parents
15:42But his mother had died when he was eight
15:44And just a few months before Maxwell arrived in Aberdeen
15:47He lost his father
15:49Maxwell expressed his grief in a letter to a friend
15:53But the passage gives a revealing insight into his humanity
15:57And the deep feelings he had for family and friends
16:00Either be a machine and see nothing but phenomena
16:04Or else try and be a man
16:07Feeling your life interwoven as it is with many others
16:11And strengthened by them
16:13Whether in life or death
16:16Maxwell's move to Aberdeen meant he was far from friends
16:21And amongst colleagues twice his age
16:23He threw himself into his work
16:26Whether it was his industry or his solitude
16:31Maxwell came to the attention of the college principal
16:34Reverend Daniel Dewar
16:36Dewar befriended his new professor
16:39And Maxwell became a regular visitor for dinner
16:42Which is how he met the principal's daughter, Catherine
16:46Maxwell's relationship with Catherine reveals the character of the man beyond his scientific genius
16:52Deeply affectionate, he had a lively sense of humour and a passion for poetry
16:59As their relationship blossomed, Maxwell plucked up the courage to ask Catherine to share their lives together
17:06And his marriage proposal included a poem
17:08Will you come along with me on the fresh spring tide
17:13My comforter to be through the world so wide
17:17And the life that we shall lead on the fresh spring tide
17:20Will make you mine indeed, though the world so wide
17:24No stranger's blame or praise will turn us from our ways
17:29That brought us happy days on our own burn side
17:33Maxwell married Catherine in 1858
17:36Maxwell married Catherine in 1858
17:39And throughout their lives they remained devoted to each other
17:42She would be a valued assistant in many of his future experiments
17:48And he even became a willing guinea pig for one of his great obsessions
17:52Strange as it may seem, in Maxwell's time we didn't really know what colour was
18:06Or why we saw colour at all
18:10In the 17th century Isaac Newton had given us food for thought
18:14By using a prism he had split sunlight into separate colours
18:18The familiar colours of the rainbow
18:22He showed that what we perceive as white light
18:26Is actually a mixture of different colours
18:31Newton said that every colour we see
18:34Was a result of mixing the colours we see in the rainbow
18:37He tried and failed to establish the rules of mixing
18:42150 years later we weren't much wiser
18:45Maxwell was interested in colour and why we perceive it
18:50Throughout his life
18:52And his first real breakthrough came as a Cambridge student
18:59Artists seemed to be ahead of scientists on this
19:05For centuries they had been creating a vast palette of colours
19:10Often by just mixing red, blue and yellow
19:13Artists refer to these three as the primary colours
19:17Artists refer to these three as the primary colours
19:20And using them they could create entirely different colours
19:24So if a painter was mixing red and yellow
19:28He would get orange
19:30And if he was mixing blue and red then he'd get purple
19:34But if they were mixing blue and yellow then they would get green
19:41As a student Maxwell read about the work of Thomas Young
19:47Young thought that there was something significant about the number of primary colours
19:53But he also thought biology had a role to play
19:56Young argued that the human eye had three receptors in it
20:02Each one sensitive to a particular colour
20:05He argued that the brain worked like a painter
20:08Combining messages from each receptor to build up this perception of colour
20:13It was a stroke of intuitive genius
20:16We just don't have any proof
20:18Young thought that these receptors corresponded to the painter's primary colours
20:29Taken by Young's three colour theory
20:33Maxwell wanted to test it
20:35He devised a way to mix the primary colours with mathematical precision
20:41He then tested those mixtures on a wide range of people
20:45To see if they all perceived the same colour
20:48And he did this with a deceptively simple tool
20:54So this looks old, what's this then?
20:57This is Maxwell's original colour wheel
21:00Which we are very pleased to have in the laboratory
21:01So that's the original thing?
21:04This is the original thing
21:06It's slightly beaten up, it's been used a lot
21:08And that's because Maxwell used this to test out the mixing of lights
21:13Among all his friends when he was here in Trinity College
21:16It is pretty antique as you can see
21:19But the idea is you put different amounts of the coloured papers here
21:24And then when you rotate them, then they mix up
21:26And this works because of the typical time that the eye can respond is a twentieth of a second
21:34And so if it goes faster, the eye will interpret this as a mixture of the colours
21:39And this is a motorised version, isn't it?
21:41This is a motorised version of it
21:42And we can actually demonstrate how the colour mixing works
21:45With this rather pretty demonstration here
21:48We're going to mix red and blue
21:50We'll rotate it rapidly and then we'll see which colour we produce
21:55Just like his childhood zootrope, Maxwell's colour wheel would spin so fast it would trick the human eye
22:03So if you were going to bring up that light
22:06This one here?
22:07That's right
22:09Instead of moving figures, he'd be mixing colours just as artists did
22:11But with mathematical precision
22:14When he mixed red and blue, he got the same colour artists did when they mixed paint
22:21Now that's kind of magenta purple
22:24Yes, it's a sort of magenta colour
22:26If Young was right and there were receptors in her eye that responded to the artist's primary colours
22:32Then perhaps mixing red, yellow and blue in equal measure would produce white
22:37But it didn't
22:40So Maxwell tried different combinations
22:43We can begin now to reveal green as well as blue here
22:48And if we just do a little bit of fiddling around with these discs
22:52We'll be able to get equal amounts of red, green and blue
22:56And we can then see what colours we observe
23:00OK?
23:06So it's white
23:19It's white
23:20It's the only colour you'd call that white
23:25So this is a beautiful demonstration
23:27Of the fact that the primary lights
23:30And notice the word light, not pigments
23:32The primary lights are red, blue and green
23:36And you can create any colour of light by suitable mixture of different proportions of these
23:43What happens in paintings, pigments absorb light, whereas this is emitting light
23:48So the upshot of all of this was that Maxwell was able to produce a rather beautiful colour triangle diagram
23:54Which could indicate how you would create any colour by mixing the three primary colours
24:00Maxwell's colour triangle allowed him to pick a specific colour
24:06And work out how much of each primary colour would be needed to reproduce it
24:11This was made possible by his mathematical precision and systematic testing
24:16Maxwell's work swept aside a sea of confusion
24:19He vindicated Young's theory and demonstrated that we see colours in paints differently to the way we see colours in light
24:29He established the primary colours for light as red, blue and green
24:35He realised the receptors in our eyes were sensitive to those three
24:39And then by mixing them we perceived a vast range of colours
24:46A few years later
24:50He provided a stunning display that he was right
24:55In 1861 Maxwell was invited to the Royal Institution in London to give a lecture on colour vision
25:05But he didn't want to just talk about the principles
25:12He wanted to demonstrate them to his audience
25:20What he did would astonish them
25:24Maxwell took three photographs of the same object
25:27Each photo had a different filter on it
25:30One was red, one was green and one was blue
25:32That gave Maxwell three photographic plates that he could use to project an image with
25:39When Maxwell projected the image from the red photograph onto the wall
25:44He got a red picture
25:46In an age when photography was black and white this was interesting
25:51But hardly revolutionary
25:53But if you project all three images onto the wall at the exact same spot
25:58Something special happens
25:59The audience were looking at the world's first colour photograph
26:10They were stunned
26:13Maxwell had chosen the perfect subject for his picture
26:17A brightly coloured tartan ribbon
26:20By layering red, green and blue images on top of each other
26:22Maxwell established the possibility of creating colour photographs
26:32150 years later
26:37We use this method daily
26:39Because this three colour principle is used in colour TV, computer screens, even mobile phones
26:44The colours we see on our screens, however big or small, are created by carefully mixing the primary colours
26:55Maxwell's work on colour provides the basis for our present understanding of colour vision
27:03He even proposed an explanation for why some people were colour blind
27:07He said the receptors in their eyes were faulty
27:11And that this radically altered how they perceived colour
27:14Three weeks after his colour show, Maxwell was elected to the Royal Society for his work on Saturn's rings and on colour
27:23He was now counted amongst the finest physicists in Britain
27:27And he was 29
27:28Despite his success, a year earlier, Maxwell had found himself out of a job
27:38When Marshall College merged with Aberdeen University, he had lost out to an older professor
27:45Out of work, Maxwell and Catherine took a trip to the country
27:49To somewhere very special to James
27:51A quiet place, hidden deep in Galloway, just west of Dumfries
27:59A place called Glen Lair, his family home
28:03Maxwell's family had been established in the area for centuries
28:08And Glen Lair was a working estate
28:11He was born in Edinburgh, but James had spent an idyllic childhood here
28:17Playing in the fields, swimming in the stream, running through the woods
28:25Nature truly was his playground
28:28And that fostered the curiosity about how the natural world worked
28:35For the first decade of his life, Maxwell was home schooled by his mother
28:39She encouraged his inquisitiveness
28:41Look up through nature, she said
28:44Up to nature's God
28:50Glen Lair remained an important place to Maxwell throughout his life
28:54It was somewhere that rooted him
28:57A safe haven, a home
29:01And the current owner of Glen Lair knows just how that feels
29:05So what was it like growing up at Glen Lair?
29:08Well, I was a ten-year-old little boy when I came here
29:13And I had the run of the place
29:17My dad was quite an old chap
29:19And he and my mother, and I was an only child
29:23They were elderly, so they didn't really keep an eye on me
29:27My childhood must have almost mirrored his
29:30Although I was slightly older
29:31But I mean, a lot of his stuff's theoretical
29:34It's kind of just thinking, difficult thinking
29:37This seems a good place for theoretical thinking
29:40Yes, yes, and we have loads of professors who visit here
29:44And nearly all of them stand here
29:47And they look out at that view
29:49And they say, I know how he could do it
29:52Because it just inspires you
29:55Yeah
29:57Try to encapsulate Maxwell
29:59What is he for you?
30:01What do you think of him more than anything else?
30:04What appealed to me about Maxwell
30:07Is how normal he was
30:10As a boy
30:12That he loved outside
30:14He loved the open air
30:16He loved all the creatures
30:18And the gardens and the trees you see around here
30:21Thanks to Maxwell
30:23But it's that emotional attachment that you feel to him
30:25Yeah, it's the way he loved it here
30:28Like I love it here
30:30I've been offered lots and lots of money
30:32To sell this place
30:34There's no way they're going to get me out
30:36Except in a box
30:40Like Duncan, Maxwell felt a strong connection to Glen Lear
30:44His proposal poem to Catherine had been about sharing their lives here
30:49They'd even honeymooned in Glen Lear
30:52When they returned here in 1860
30:55It wasn't just a holiday
30:57On the death of his father, Maxwell had inherited over a thousand acres of farmland
31:03Dozens of working people relied on decisions he made
31:08There were fields to sow, animals to tend, buildings to construct
31:14He raised funds to build a church
31:17And was keen to improve local schooling
31:21It was a responsibility he took seriously
31:24And every summer, Maxwell and Catherine returned here to oversee the estate
31:29And recapture some of the childhood peace he'd found here
31:34But Maxwell wouldn't stay at Glen Lear
31:38He wanted to be in the thick of scientific research
31:40And that meant a university
31:44After a rejection from Edinburgh
31:47He accepted a position at King's College London
31:50Whilst there, he would produce his finest work
31:53And unravel one of the great mysteries of his age
31:56Maxwell arrived in London at the end of 1860
32:09And assumed teaching duties immediately
32:12While there, he focused on a subject that had captured his attention many years before
32:17Ever since his early days at Cambridge, Maxwell's been interested in electricity
32:24After it was suggested as an area to look at by a friend
32:27That friend's advice was simple
32:32If Maxwell wanted to learn something about electricity
32:35He needed to know Michael Faraday
32:36Faraday
32:39Faraday was a self-taught scientist who was revolutionising our understanding of electricity and magnetism
32:46Maxwell's relationship with him was one of the most fruitful in 19th century science
32:54We'd known about electricity and magnetism since ancient times
33:01Most people had experienced the power of electricity through terrifying lightning storms
33:07And we'd used magnetism in ships' compasses for centuries
33:12They were considered completely separate things for most of our history
33:22But in the early 19th century, scientists like Faraday were beginning to see a mysterious connection between the two
33:32Deep in the heart of the Royal Institution, Faraday conducted experiments to understand how they were linked
33:38In one experiment, a copper wire carrying electricity somehow provoked a nearby compass to move
33:52In another, Faraday tried to do the opposite
33:57Use a magnet to generate electricity
34:00Which led him to invent the electric generator
34:03Which is an example where you have a permanent magnet
34:07And a coil of wire
34:09So the wire is wrapped around this bit
34:11The wire is wrapped around a cylinder
34:13And you push and pull the magnet in and out of the cylinder
34:16To generate an electric current
34:18I like the lights, what's the Christmas lights for then?
34:21Well that's to show the electricity is passing
34:25Faraday did not use light emitting diodes
34:28I think he should have done, that was his great mistake
34:29And all electricity power stations throughout the world use as principle of generate electricity that Faraday discovered down here in 1831
34:41Faraday had generated electricity simply by moving a magnet through a coiled wire
34:46A discovery that would forever be associated with his name
34:50But he was left with perplexing questions
34:53There was no physical contact between the electric wire and the magnetic needle that moved
34:59Nor between the moving magnet and the copper coil
35:03They were affecting each other through seemingly thin air
35:08But how could that be?
35:11Now what Faraday thought was happening was that there were lines of force
35:14Coming out at the end of the magnet which were then cutting the wire within the coil to move electricity around the coil
35:28The idea of mysterious lines coming out of the magnet to generate electricity may have seemed outlandish
35:35But Faraday had a simple experiment that could prove their existence
35:38So he took a very powerful permanent magnet
35:43Placed some paper
35:46On it
35:48Sprinkled iron parlings
35:52Over it
35:56Just to represent
35:58The lines of force
36:00It never fails to impress that
36:03Of the magnet and you can see the three dimensional
36:06So these are coming up here and swinging around
36:10And then coming down into this
36:12And Faraday sort of made permanent examples of this and sent them around to all his mates in Europe
36:19To show that space has structure as a very strong argument for his field theory
36:24So Faraday thought there was an invisible force field at work here
36:27Well literally a field, I mean Faraday still brings the word field into science
36:33And it's invisible as you say
36:35So this is why this is just a representation
36:38It shows the existence of those invisible lines
36:46Faraday's iron filings experiment revealed the existence of an invisible field stretching out into thin air
36:51These fields, he thought, were responsible for the experimental results he'd seen
37:03Despite having physical proof
37:05Faraday lacked a mathematical description of how the field was generated
37:10Or why it affected things around it
37:12Without a mathematical proof
37:17Many 19th century scientists dismissed the theory as speculative
37:21But Maxwell had followed Faraday's work for years
37:25And set out to prove him right
37:28Maxwell had plenty of time to mull over the problem
37:32The walk from his Kensington home to King's College was an eight mile round trip every day
37:47And during the walk, he allowed his mind to wander
37:51On those walks, and at work, he had company
37:56Apparently Maxwell always had a dog
37:59And he always called it the same name
38:02From childhood onwards, every dog was called Toby
38:05And Toby, whichever one it was, rarely left his side
38:10Toby was a constant companion at home and in the lab
38:14It's a sign of Maxwell's eccentricity that he would talk to Toby
38:18He said he liked his company
38:20During his walks to and from work, Maxwell, and perhaps Toby
38:24Broodied over the mysterious relationship between electricity and magnetism
38:36His aim was to provide a mathematical explanation for the link between the two
38:43After years of thinking, and who knows how many miles walking
38:47He came up with a set of equations that describe the relationship between electricity and magnetism
38:52Equations that would change our lives forever
38:58Sorry Frank, but this is just gobbledygook to me
39:01I'm just looking at it, trying to make sense of it
39:03Well, it's not much easier for me
39:05I mean, that's what he wrote first of all
39:08And looking at these, they probably mean little more to me than to you
39:11But 20 years later, they were written in a simpler form
39:14Which is the way that students describe this form here
39:16That looks more manageable, but it still looks a bit confused
39:20Could you take us through it then?
39:22Right, well the first one says that if you've got an electric charge
39:26It spreads an electric field out all over space
39:29Just like his work on Saturn's rings
39:32Each equation is a mathematical description of something observed in the real world
39:36So the first equation describes how a static electric charge generates an electric field
39:49And the second, that magnetic poles always come in pairs
39:53The third equation describes how a changing magnetic field generates an electric field
40:00And the fourth equation, that an electric current surrounds itself with a magnetic field
40:08But Maxwell realised there was something missing
40:12Maxwell's genius was to realise that each of these equations is fine until you put them together
40:19And then he realised something was missing and it was in this final equation
40:23He said, there has to be another term
40:25And what this extra piece says is if an electric field is changing
40:37It will surround itself with a magnetic field
40:40Which is like the sort of mirror of this equation
40:43Which says if a magnetic field is changing, it will surround itself with an electric field
40:48So just take these two together and just think about it for a second
40:51If I've got a magnetic field changing, it surrounds itself with an electric
40:56If the electric is changing, it surrounds itself with a magnetic
40:59And if that is changing, it will surround itself again with an electric and so on
41:03Faraday to Maxwell, electric to magnetic, back and forth, back and forth
41:07So there's a coupling basically between the two
41:13Maxwell's equations were saying that electric and magnetic fields were inextricably linked
41:17Changes in one created changes in the other
41:22It helped explain so much
41:28When Faraday moved his magnet, he changed the position of the magnetic field
41:33And this triggered an electric field which caused electricity to flow through the wire
41:37And when electricity passed through a wire
41:40And when electricity passed through a wire, it wrapped a magnetic field around it
41:44Causing the compass needle to move
41:50Using pure maths, Maxwell had unified electricity and magnetism
41:56And shown there were two aspects of the same thing
41:59A single electromagnetic field
42:01This alone would have guaranteed Maxwell's entry to the scientists' hall of fame
42:10He could have rested on his laurels
42:12But whether it was his natural curiosity or the long walks with Toby, he didn't stop there
42:19He used his equations to test another of Faraday's ideas
42:22Faraday had guessed that under certain circumstances
42:28The electric and magnetic field lines could be disturbed by waves travelling along them
42:33Almost like ripples on the surface of water
42:43Maxwell used his equations to show that the fields could fluctuate in time with each other
42:47And caused what Maxwell called an electromagnetic wave
42:52He could even measure the speed of the wave
42:56This says the electromagnetic wave travel through space
43:00And buried in here, he was able to extract the speed that the wave travels
43:07And when he put the numbers in, from things that Faraday and others had already measured
43:10He worked out the speed and it came out as a phenomenal 300,000 kilometres every second, roughly
43:17And that, I think, is the moment of discovery
43:20Because he knew that people had measured the speed of light
43:25Which was 300,000 kilometres every second
43:27Now at this moment you think, is this a coincidence
43:30Or are these equations telling me something?
43:32And of course they're telling you something
43:34And what the message is, light is an electromagnetic wave
43:37This was a stunning conclusion
43:42Maxwell had explained what light itself was
43:48At the same time, he'd introduced something new to science
43:52Electromagnetic waves
43:55And they were destined to change our planet
43:58The problem was, he hadn't physically demonstrated the existence of these waves
44:04It was all in the maths
44:08Physical proof would have to come later
44:11His equations were an astonishing piece of work
44:15Packed with radical ideas
44:18Maxwell gave us a unified theory of electricity and magnetism
44:22He solved the mystery of what light was
44:24And he predicted the existence of these invisible fields that would directly affect our life
44:29You know, that's difficult enough to grasp for a 21st century scientist
44:34But what on earth did the Victorians think?
44:39The fact is, Maxwell was asking a lot from his peers
44:42Invisible fields, undetected waves, dense maths
44:47It's all a bit much for 19th century scientists
44:50Ironically, Maxwell found himself in a similar position to Faraday
44:55Surrounded by sceptical colleagues
44:58And lacking the proof to vindicate his theory
45:01But a jubilant Maxwell was undeterred
45:04He wrote an excited letter to his cousin
45:07I also have a paper afloat
45:10With an electromagnetic theory of light
45:12Which until I am convinced to the contrary
45:15I hold to be great guns
45:17The guns may have fired
45:19But it would be a while before they'd be heard
45:21It took more than 20 years before a German scientist called Heinrich Hertz
45:27Found physical proof for electromagnetic waves
45:30When he was asked what practical use the wave had
45:33He replied, it's of no use whatsoever
45:36This is just an experiment that proves maestro Maxwell was right
45:44How wrong he was
45:46Because Hertz had discovered radio waves
45:48Marconi invented the radio
45:51And since then we've been using them to spread radio and television all over the planet
45:56But this was just the first in a long list of discoveries
46:00Happy days are here again
46:04Using higher frequency radio waves we developed radar
46:08Which now gets used in everything from aviation to geology
46:12Microwaves were discovered
46:14Which we use in cooking and when we use a mobile phone
46:16Infrared is used in thermal imaging and in most TV remote controls
46:22Ultraviolet is used in fluorescent lamps
46:25Security marking and medical research
46:27X-rays have provided us with a valuable medical tool
46:31But more recently in security
46:33And gamma rays have been used to detect and treat cancer
46:37And even to sterilise the food we eat
46:40All these things are connected
46:42Maxwell had shown that light and the colours we see are electromagnetic waves
46:49But he predicted there would be more
46:52Today we know that visible light is just a tiny sliver of a broad spectrum of electromagnetic waves
46:59And by understanding and exploiting them we've revolutionised our world
47:04All thanks to equations Maxwell published 150 years ago
47:14That was all part of a future that Maxwell wouldn't see
47:18When he first published people didn't understand him
47:23You know back in 1865 there was no sign, no evidence of these mysterious electromagnetic waves
47:29Maxwell was asking people to believe that these waves could pass through empty space
47:35And affect things at a distance
47:37It was just too much to ask
47:40His equations were initially met with a bewildered silence
47:44Nineteenth century scientists were used to thinking of the world in mechanical terms
47:49Physically tangible objects that could be touched, measured and felt
47:53Flying in the face of that was Maxwell's theory
47:57Based on dense mathematics and visible fields and undetected waves
48:02Many thought Maxwell's theory was a kind of abstract mathematical speculation
48:08That he had strayed too far from physical reality
48:12That he was, in essence, away with the fairies
48:16Maxwell became convinced that he had to develop his theory of magnetism and electricity
48:20Not long after that publication, he decided to pursue his own interests
48:26And resigned his post at King's
48:28He was going home
48:30After the lukewarm reaction to his 1865 publication
48:34The comfort of Glenn Lair was welcome
48:36Ever industrious, Maxwell produced papers on thermodynamics
48:38And even topology
48:39But always he returned to his electromagnetic theory, slowly refining it
48:55After six years in the wilderness, Cambridge University approached him
48:58They wanted someone to plan and run a lab in experimental physics
49:02Despite all his achievements, Maxwell was third in line, after two other candidates had rejected the offer
49:19In 1871 he left Glenn Lair for Cambridge, where he designed and built the Cavendish Laboratory
49:25Which would be responsible for discoveries that shaped physics in the 20th century
49:31And as its first director, his open-minded approach set the tone for subsequent generations
49:39I never try to dissuade a man from trying an experiment
49:44If he does not find out what he wants, he may find out something else
49:48The Cavendish Lab would become a phenomenal success
49:55It's within these walls that we discovered the electron
50:01And later on, the neutron
50:03Watson and Crick were working here when, in 1953, X-rays were used to show the structure of DNA
50:12The Cavendish is now widely regarded as a centre of excellence
50:18And has produced 29 Nobel Prize winners to date
50:24But every summer, Maxwell returned to Glenn Lair
50:28Patiently working out the full implications of his electromagnetic theory of light
50:32In 1873, Maxwell released a dynamical theory of electricity and magnetism
50:52The intervening years had allowed his colleagues time to digest his theory
50:55And it was starting to gain traction
50:59But he wouldn't live to see it vindicated
51:02When guests were visiting Glenn Lair in 1879, Maxwell found that he could barely walk down to the river
51:09Such was the pain
51:11The pain was in his stomach
51:13In October of that year, he was diagnosed with abdominal cancer
51:17Given a month to live
51:19Maxwell was just 48 when he received the news
51:31He knew his mother had died at the same age
51:36From the same disease
51:37Nevertheless, he accepted his fate with a calm stoicism that had defined his life
51:50Catherine nursed him as best she could
51:55It's said that on his deathbed, Maxwell breathed deeply
51:59And with a long look at his wife
52:01Passed away
52:02James Clark Maxwell died in November 1879
52:15He was buried in Parton Kirk
52:18His childhood church
52:20Just a few miles from his beloved Glenn Lair
52:21He lies in a modest grave next to his parents
52:35And seven years later, Catherine would be buried next to him
52:43Apart from a plaque outside the cemetery, there's nothing to mark this grave as different from any of the others
52:48There's no list of grand achievements, it's just simple and modest
52:54Like the man himself
53:01A visitor could be forgiven for passing the grave without a second glance
53:06But for some, this is a special place
53:14There's a story that's told around Parton Kirk
53:16Shortly after the fall of the Berlin Wall
53:19Two buses arrived
53:21And people filed into the graveyard
53:23A curious local asked who they were
53:27They were, they said, Russian scientists
53:29Who had travelled to visit the grave of Scotland's Einstein
53:36You know, Maxwell died at a relatively young age
53:3848
53:40Which even by the standards of his day was an untimely death
53:43And you just wonder, you know, given the achievements that he had in his lifetime
53:48What he would have conjured up if he'd lived
53:51If he was 60 or 70
53:53Maxwell may not have been fully appreciated in his time
53:57But in the decades following his death, scientists started to recognise his genius
54:01Eight years after Maxwell's death, Heinrich Hertz discovered radio waves
54:14Proving beyond doubt the existence of electromagnetic waves
54:17The rest, as they say, is history
54:23Over a century later, these waves have changed our planet
54:29And are part of our everyday lives
54:31But focusing on the technological results of his work diminishes its importance
54:42Because he changed the way we understand reality itself
54:46Before the work of Maxwell and of Faraday, just before on the experiments
54:51We understood the world in terms of springs and cogs, a machine-like world
54:54And that machine-like world was pretty primitive
54:59What Maxwell's work showed is the way that we understand the interaction between material bodies
55:07Is via this idea of a field
55:10Not the sort of field we're standing in
55:12Not a green field
55:14Not a green field
55:16But something that penetrates space
55:18And which really governs the way the world behaves
55:20Maxwell helped overthrow the mechanical model of the universe that physicists had held since Newton
55:29And issued in a new era
55:32We now think of all the forces in the universe interacting through fields
55:38Rather than direct physical contact
55:40This was a crucial shift in our understanding
55:46Prompting Einstein to say
55:47One scientific epoch ended
55:50And another began
55:52With James Clerk Maxwell
55:57Which is perhaps
55:59Why still revered by scientists today
56:08This meeting we're having here in Edinburgh today is very special
56:12We're celebrating the 150th anniversary of Maxwell's publication of his equations of electromagnetism
56:21Some of Britain's finest scientists gather at an event to remember the life and work of James Clerk Maxwell
56:29Maxwell is all around us
56:32Every single piece of technology that's around us today
56:35Computing, fibre optics, cameras, mobile phones
56:40Everything depends on extensions of those Maxwell's equations
56:45Without those we wouldn't be where we are today
56:50Even the internet doesn't exist without them
56:53Maxwell changed the way we think forever
56:57You can't
57:02Overestimate his contribution
57:04His influence on everything
57:06Both practical and theoretical
57:08He is the most remarkable Scot
57:11Intellectually
57:13That has ever arisen
57:15No question about it
57:17In terms of the sequence of great men of physics
57:21Starting with Galileo and Newton
57:24Then comes Maxwell
57:26And then Einstein
57:28Who said that Maxwell was the greatest physicist
57:33After Newton
57:35It's wonderful to be sitting in the audience of a meeting
57:38Surrounded by Nobel Prize winners
57:41The great and the good
57:42There's a sense of
57:45Shared excitement
57:47It's unapologetic geekiness
57:50That however
57:52The people like Peter Higgs
57:54And Nobel Prize winners
57:56We are still in awe
57:58Of this giant of physics
58:01And having got to know the man
58:03I can understand why
58:05I can't blame people for not knowing about James Clerk Maxwell
58:09His is difficult stuff
58:10I just think that given the breadth of his discoveries
58:14And the sheer impact I've had
58:16That it's a travesty
58:18Maxwell's name is not up there with Newton and Einstein
58:20As one of the greats
58:22Maxwell is Scotland's Einstein
58:25And we should remember him as such
58:33What would it be like to take a journey into the mind
58:35Of the world's most famous physicist
58:37Go to BBC iPlayer
58:38To watch the animation short
58:40Inside the mind of Professor Stephen Hawking
58:42Here on BBC4 though
58:44Dredging up the secrets of the Spanish Armada and the Mary Rose
58:47In part one of Shipwrecks
58:49Britain's sunken history
58:51Next
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