STEPHEN HAWKING: Let me take you back in time
to a place without the wonders of the modern world.
500 years ago, the Earth was dark,
a place of mystery and superstition.
But then science changed everything.
This series will tell the stories
of the British scientists who changed the world.
We have asked some of the great scientists and inventors of today
to tell us about their heroes.
Now let's start her up.
It opened up a whole new world of the very small.
Heat was Thomson's big idea. To me, Hunter is a true hero.
Exciting possibilities.
He made science in Britain really matter.
Britain has a tremendous scientific legacy
that most people know little about.
We want to set the record straight
and put science back on the map.
The world is full of wonders, but they become more wonderful
when science looks at them.
STEPHEN HAWKING: I was born in January 1942
when Britain was in the midst of the darkness of war.
With London in ruins, no-one then would have predicted
a bright future for British science.
But I found myself growing up in an era of astonishing discoveries.
For all the achievements of those who had gone before,
two big questions remain to be answered.
One was, how did the universe begin?
And the other, what is the secret of life?
We want to tell you the story of these great breakthroughs,
show you some of the most exciting recent discoveries...
and ask each other the questions that most puzzle us.
Do you think there will be scientific geniuses in a world of super-computers?
RICHARD DAWKINS: Cambridge after the war was a city of battle-weary academics
and students who had already seen the harsh side of life.
This small university city was about to be the centre
for not one, but two of the most significant discoveries ever made.
On February 28th 1953,
two rather wild young men burst into this pub in Cambridge, The Eagle,
and announced to anyone who would listen
that they had discovered the secret of life.
What they discovered was the structure of DNA,
the genetic molecule,
the physical trace of the universal database of all life.
It was more than just a structure.
Written all over it was what it does.
It has the extraordinary capacity to make almost exact copies of itself.
Like every biologist of my generation,
I'm hugely indebted to those wild young men
and their truly inspirational research.
They were an unlikely pair, not what Cambridge was used to.
The brilliant, drivingly ambitious young American, Jim Watson,
and his clever, larger-than-life English colleague,
the garrulous Francis Crick.
They were irreverent, arrogant even,
searching for nothing less than the secret of life,
what Watson himself referred to
as the most important event in biology since Darwin.
Nearly 100 years earlier,
Charles Darwin had published his great book, The Origin Of Species,
and the theory of evolution broke upon the world.
But while Darwin's theory explained how life had evolved,
one key piece of explanation was missing.
How and why was this information passed down from parent to child?
That is the secret of life,
and for a generation that had just gone through a devastating world war,
solving this mystery was one of the great challenges facing science.
In this quest, Crick and Watson had one great advantage.
Each other.
If, for example, I had some idea
which as it turned out would, say, be quite wrong,
was going off at a tangent,
Watson would tell me in no uncertain terms this was nonsense.
Well, Francis likes to talk.
It's his dominant quality, I think.
He doesn't stop unless he gets tired or he thinks the idea's no good.
It's useless working with somebody who's either much too junior than yourself
or much too senior, because then politeness creeps in,
and this is the end of all real collaboration in science.
Crick and Watson understood each other. That was essential.
But the problem before them was immense.
For some decades, scientists had thought that a substance called DNA,
found in all living cells, might play a key role
in transferring information from one generation to another.
But no-one knew how it could do this.
Perhaps if they could see into its structure,
they might be able to discover how it worked.
But looking closely at DNA was very difficult.
Direct visualisation, as with a microscope, couldn't work.
The scale was too small.
But there was an indirect method involving X-rays,
and X-rays were already being beamed at crystals of DNA,
just 50 miles away, in London.
OLIVIA JUDSON: She is one of the heroines of British science,
sometimes called the "Dark Lady of DNA".
Her name was Rosalind Franklin.
A young woman in the then male-dominated world of King's College, London,
she, like Crick and Watson, was trying to visualize the structure of DNA.
And Rosalind had skill on her side.
She was an expert in X-ray diffraction,
a way of capturing images of atomic structure.
But the kit she had to work with was incredibly basic.
The new biophysics department at King's was a pretty ramshackle place.
A lot of the equipment was borrowed from colleagues at other London colleges
and this camera was army surplus.
The DNA came from the thymus gland of a calf in Switzerland
and in order to take pictures of it, it had to be suspended on a paper clip.
You put it in here,
you look through the eyepiece and line it up to make sure it's straight,
then you put a piece of photographic paper here and bombard it with X-rays.
The X-rays hit the crystal
and scatter the light, giving you a pattern of dots.
If the image is sharp enough and the sample was lined up properly,
you might be able to work out what the structure of the crystal is.
Rosalind was extremely determined - little would stop her.
The X-rays were done at night when there weren't many people around
because King's College was afraid there might be leaks from the lab.
But it wasn't Rosalind who made the first breakthrough.
It was her colleague, Maurice Wilkins.
Early in 1951, Maurice Wilkins took a photograph of DNA
that suggested it had a regular structure.
The story goes that one night, he came outside for a breath of fresh air
and looked across the river at the OXO Tower.
The famous logo gave him an idea.
Perhaps the structure in the picture was shaped like an X,
which might mean DNA was a helix, or spiral shape.
This was a vital insight
and perhaps, if they had been able to work together, Maurice and Rosalind
could between them have begun to crack the mystery.
But that was never going to happen.
Rosalind comes across
as a very private person, a loyal and thoughtful friend,
very honest, a brilliant scientist and a dedicated one.
But she also had a fierce temper and contempt for those she didn't respect.
She refused to collaborate with Wilkins and didn't show him her data.
So when she took this photo,
she didn't show it to Wilkins, or indeed, anyone else.
This is the famous photo 51, a blurry image,
but one which holds the key to the secret of life.
In this picture are vital clues needed to discover the shape of DNA.
But Rosalind Franklin tucked the picture away in a drawer,
and there it might have stayed, if it wasn't for Wilkins.
Over eight months later, in January 1953,
James Watson made one of his occasional visits to King's.
Wilkins, who worked in the same lab as Rosalind,
said he had something to show him.
For Watson and Crick, this was the crucial piece of evidence,
the clue that would allow them to deduce the structure of DNA.
The pattern of spots on photo 51 showed clearly that DNA was a helix.
RICHARD DAWKINS: Watson saw immediately the value of this information.
He hotfooted it back to Cambridge with this vital clue.
But it's what he and Crick did next that made all the difference.
They knew it was a helix, but now the question was, what sort of helix?
Their approach was very hands on, making giant 3-D models
of all the different shapes they could think of that might fit the picture.
They tried model after model,
each one a hypothesis for a three-dimensional structure
that might explain Franklin's X-ray results.
Watson and Crick worked at a furious rate.
The machine shop which supplied them with the tin bases for their models
struggled to keep up.
But the pieces of the puzzle all fell into place in February 1953.
Rosalind Franklin's X-ray pictures, and her measurements on them,
enabled Watson and Crick to work out that DNA had to be a double helix.
Their original model has unfortunately been destroyed.
This is a half-scale replica.
You can see the two spirals going around like that,
forming a kind of spiral staircase,
and the steps of the spiral staircase are the so-called bases.
There are only four kinds of them
and they are in pairs - each step is one pair.
The shape plays a vital role in the way DNA works
because the double helix can split perfectly and then re-form.
The reason we're all different
is that we're born with our own particular sequence of these base pairs,
with half of each pair inherited from each of our parents.
Crick and Watson had indeed made the first step
to uncovering the secret of life.
They'd done it.
Surely they'd had a lot of luck
but let's not take away from their achievement.
As Crick himself said,
"It's true that by blundering about we stumbled on gold,
"but we were looking for gold."
And the biggest nugget of all?
Forget all mystical ideas of an essence of life or a life force.
From now on, the essence of life was just bytes and bytes and bytes
of digital information.
But the story didn't end there.
What's perhaps even more exciting
than what Watson and Crick did in the 1950s
was what Crick went on to do in the 1960s.
Cracking the genetic code itself.
Crick knew that DNA was information, a code for life.
A message lurked in the sequence of DNA bases which was translated
into a corresponding sequence in a different kind of molecule - protein.
There must be a dictionary,
a look-up table, from DNA sequences to protein sequences.
That was the elusive genetic code,
and that was what Crick set out to break,
and what he came up with was an ingenious experiment.
He began with a virus and then mutated its DNA.
He found that if he removed a single base,
the virus would no longer work.
This meant the original message the virus DNA was carrying was disrupted.
The same was true when he removed two bases.
If he removed three bases, however, the original message was restored.
The virus was back to normal.
It now remained for others to fill in exactly what each triplet means,
but perhaps the vital step in the whole molecular genetic revolution
was Crick's discovery that it was a triplet code.
It opened up a whole new world of understanding
that couldn't have been dreamed of
before Crick and his colleagues came on the scene.
Since this great discovery, the advances have come thick and fast.
We now have a biotech industry worth billions.
We can identify medical problems in the womb, identify crime suspects
using unique DNA fingerprints,
sequence the entire human genome
and even clone new life.
While Watson and Crick struggled to solve the mystery of life,
in another part of Cambridge,
the physicists had their own big question -
how did the universe begin?
While Crick and Watson were unravelling the shape of DNA,
another huge question was being tackled just a few hundred yards away.
How did the universe begin?
It's the question I have spent my life grappling with.
The story starts for me with the controversial genius
who was one of my inspirations for studying at Cambridge.
Fred Hoyle.
JIM AL-KHALILI: In 1948,
the nation listened enthralled to a series of radio broadcasts
from a gruff Northerner, describing the inner workings of the universe.
FRED HOYLE ON RADIO: Well, then, what is the stars?
What is the insides of the stars, and what is in the depths of space
beyond the bright girdle of the Milky Way? Come to that, what is the universe?
AL-KHALILI: One producer said that Fred Hoyle
described interstellar space as if it were a cricket match.
But Hoyle did more than bring the universe into our living rooms.
He revolutionised our understanding of it, and of ourselves.
For 25 years, Fred Hoyle was the most famous astrophysicist in the world,
and the man who kick-started the debate about the origins of the universe.
I've come to where he was born, in the village of Gilstead,
to find out where his interest came from.
You might think of scientists as being a bit geeky,
heads always buried in books, always studying.
Well, Fred Hoyle wasn't like that.
He was always playing truant from school, either down by the canal
near where he lived, or out here on the moors, even in weather like this.
In fact, he loved the outdoor life, hiking, mountaineering.
He even courted his wife-to-be while out on a hiking trip.
But there's another side to Fred Hoyle.
Curiosity.
He used to say about the hours he spent mucking about on the canal
that he was instinctively displaying a sound sense of engineering.
Watching the lock gates and the sluices open and close
was much more valuable,
he thought, than anything he could have learnt at school.
Even at an early age, Hoyle was remarkably self-confident.
"Cocky" might be a better word to describe him.
And throughout his time at Cambridge, he was famous for his belligerence
and for speaking his mind.
And he was a constant thorn in the side
of the British scientific establishment.
Hoyle turned his attention to the biggest question of all.
How did the universe begin?
By this time, scientists knew that the universe was constantly expanding,
but why hadn't it run out of steam?
And where had it started from?
Hoyle enlisted the help of two old friends
from his wartime days in radar research,
Hermann Bondi and Thomas Gold,
and the three of them spent hours here in Bondi's rooms in Trinity College
talking, arguing and just plain thinking.
But when the eureka moment came,
it was quite sudden and from an unexpected source.
Hoyle, Gold and Bondi went to see the thriller Dead Of Night,
a kind of 1940s version of Groundhog Day,
when the hero is trapped in a repeating pattern of events.
The film is about a recurring nightmare,
and when Gold next saw Hoyle and Bondi,
he said, "Suppose the universe is like that, with no beginning and no end?
"Just constantly recycling."
Hoyle and Bondi seized on the idea
and they made it the basis of their brand-new theories of the universe.
What Hoyle suggested was that the universe didn't begin suddenly
but had always been there in what he called a "steady state".
I remember, I think it was on 10th February 1948,
that one evening I got down and really got the equations on paper.
I remember I had them somewhere about ten o'clock in the evening,
and I sat up till three in the morning,
and by then, I had the solution that I wanted.
In Hoyle's universe, galaxies speed away from each other
and new matter is continuously created to fill the gaps they leave behind.
These ideas were controversial,
and Hoyle was keen to let the whole world know about them,
and within a year, he got his chance.
The most obvious question to ask about continuous creation is this -
where does the created material come from?
Well, it doesn't come from anywhere.
Material simply appears, it'screated.
At one time, the various atoms composing the material don't exist,
at a later time, they do.
JIM AL-KHALILI: But it wasn't long
before Hoyle's ideas were challenged by other scientists.
This is a carbon copy of a radio talk he gave in March 1949,
in which he invented the term "big bang".
Now, Hoyle used it as a derogatory term.
He thought it was a bit like
a girl suddenly jumping out of a birthday cake.
It was a party trick, not a real scientific theory.
Here's what he has to say.
"It's an irrational process that cannot be described in scientific terms.
"On philosophical grounds too, I cannot see any good reason
"for preferring the big bang idea."
The idea of the Big Bang is that the universe was created suddenly,
in a single explosive moment.
And while Hoyle poured scorn on the theory,
it was gaining credence
among other scientists.
But Hoyle's capacity to generate ideas,
however controversial, drew students to Cambridge.
Among them was a young PhD student called Stephen Hawking.
Stephen Hawking was destined to become the most famous physicist since Einstein.
But he'd not been a particularly promising child.
He'd not learn to read until he was eight.
He hadn't even been in the top half of his class at school.
And he did make it to Oxford,
but then it was a close-run thing whether he'd get a First.
When he moved to Cambridge to study for his PhD,
Hawking realised that he had no interest in day-to-day astronomy,
and that, like Hoyle,
he wanted to use mathematics to investigate the universe.
The hot topic of research in the 1960s was black holes.
Now, it was Einstein's theory of relativity
that first correctly explained how stars collapse to form black holes.
It said that there are points in the universe
where space is sucked in on itself.
In 1965, mathematical physicist Roger Penrose
devised an equation that explained
how everything was sucked into the centre of a black hole,
creating a sort of plughole in space,
where matter, light and energy disappear,
where time and space end.
It was Hawking's genius to take this idea and reverse it...
..showing how the Big Bang itself was the opposite of a black hole.
An explosive moment in which the entire universe
emerged from a pinpoint and shot outwards, forever expanding.
At the moment of the Big Bang, black hole behaviour was reversed,
so rather than everything being sucked in,
now space, time and energy
all suddenly burst out of the singularity.
If this explanation was correct,
then Hoyle's steady state theory was simply wrong.
Hawking did much more than cast final doubts
on Hoyle's steady state interpretation of the universe.
He went on to develop a theory
about the behaviour of particles on the edge of a black hole.
He still hopes to develop a mathematical theory
that will draw the many ideas of physics together.
A theory of everything.
HAWKING: Just as Roger Penrose's equation
triggered off my own thoughts about the Big Bang,
so one breakthrough led to another in our understanding of life.
The man who took us one step further was Bill Hamilton.
RICHARD DAWKINS: For more than 30 years, Bill was, variously,
my inspiration, colleague, mentor and friend.
He was a shy and forgetful man,
in equal parts very deep thinker and very knowledgeable naturalist,
rather like Darwin, but with added mathematics.
He thought all the time, seeking biological answers to big questions.
Why do we have sex? Why do we grow old?
But he's best known for his evolutionary explanation of altruism.
Why do animals, including us,
give up our own interests for the sake of others?
I've come to Badgers Mount in Kent, because this is where Bill grew up -
in this house, Oaklea.
To him, it remained a wild paradise all his life,
a laboratory of endless curiosities.
This is Bill's collection of butterflies, made when he was a boy.
All British and all collected within walking distance of this house.
He sometimes joked that he preferred the company of insects to people.
Bill wanted to apply genetics to evolution.
He was fascinated by a big question left over from Darwin -
the mystery of altruism.
Why do animals co-operate?
Why don't we humans run an entirely dog-eat-dog world?
Inspired by the work of the great biologist Sir Ronald Fisher,
he realised that "survival of the fittest" really meant the survival of genes.
In 1964, Bill took off.
In the great tradition of British naturalists like Alfred Russel Wallace,
he took an expedition to the Amazon.
He wanted to study the social insects -
ants, bees, wasps and termites.
Their sterile worker castes fascinated him
as the ultimate genetic altruists.
These are leafcutter ants.
They're native to South America.
They forage for leaves, they cut them and carry them home.
But they don't actually eat the leaves,
but compost them for a fungus which they grow underground.
It's the mushrooms that they eat
and feed to the queen and the larvae and the other workers.
Now, from a Darwinian point of view, that could be called an act of altruism.
The workers are working for the good of the reproduction of another individual,
the queen, and that's a supreme act of self-sacrifice
in a Darwinian world.
Bill worked out that a gene for altruism would survive
if the cost to the individual was exceeded by the benefit it gave to others,
depending on how close the relationship was.
He created a mathematical formula to reflect this,
which became known as Hamilton's rule.
The theory made sense not only of ants and the other social insects,
but it also explains co-operation and mutual support
in a huge range of animals.
Bill Hamilton went on to solve
many other outstanding questions left over from Darwin,
including why we grow old,
why the ratio of males to females is what it is,
and above all, why sexual reproduction evolved at all.
An extraordinary thing about Bill
was the way he wouldn't advertise his own genius.
He'd have a brilliant idea, but then he'd bury it
in the middle of a book review or something like that,
and then attribute it to somebody else later.
I'd then have to show him his own earlier paper
in order to convince him that the idea was really his.
He'd then reluctantly admit it,
but say that the other person had expressed it better.
Bill died from complications arising from malaria at the age of 63.
I vividly remember his funeral.
Perhaps tongue-in-cheek, he'd expressed the hope when he died
that he would be laid out unburied on the floor of the Amazon jungle,
where burying beetles would inter him.
Of course, that's not the way it happened.
Bill is in fact buried on the edge of another famous forest,
Wytham Wood near Oxford.
At the graveside, his companion Louisa
invoked one of Bill's wilder theories,
and painted a picture of bacterial and fungal spores
carrying him up into the clouds
where he might eventually be rained down onto the forests of his beloved Amazon.
HAWKING: The speed at which science has advanced since I was born
is breathtaking.
Since we got our first glimpse of how the universe began,
since the structure of DNA revealed the structure of life itself,
British scientists have created the world's first supersonic airliner,
delivered the first test-tube baby, and invented the internet.
So what lies ahead?
What will be the discoveries and inventions of the next 50 years?
JAMES DYSON: I want to show you the new invention that most excites me.
One which promises to transform our world.
The most exciting possibilities of the future lie in nano-technology,
making incredibly strong materials
that are smaller than you can imagine.
These materials could even allow us to build a lift into space.
It's the modern equivalent of prehistoric man
discovering how to work with iron.
I've come to where else but Cambridge,
where some of the most impressive work is being done.
In the past, the strength of a material went hand in hand with its weight -
the stronger it was, the heavier it was.
Then in the 1980s, a British scientist called Harry Kroto
won a Nobel prize for discovering a new type of carbon.
Carbon-60 was the inspiration for carbon nanotubes,
which are incredibly tough but also very light.
Nanotubes are many times stronger than any carbon fibres currently in use.
And the surprising thing about them
is that they're not, in fact, made at all.
They're grown.
The protective clothing is necessary
to stop human hair and flakes of skin damaging the process.
Human hair is 50,000 times fatter than a nanotube
and if it got into the sample, it would ruin it.
Well, this'll be a challenge! The scientists in this lab
are letting me grow my own nanotubes,
and if things go all right, they'll develop on this silicon wafer.
It'll need an electron microscope to see it, of course.
I'll put it on this graphite heater
and put the bell jar over the top.
Now I'll switch on.
That will introduce gases into the bell jar
and the whole thing will heat up to about 700 degrees centigrade.
There's now an electric field between the black shower-head
and the silicon wafer,
and the red glow is the heater which the silicon is sitting on.
This machine produces thousands of nanotubes
too small for the human eye to see.
To give you an idea, a nano is to a football
what a football is to the Earth.
Now I can take my silicon wafer to a scanning electron microscope
to see if I've actually grown any nanotubes.
This microscope has magnification
up to 4,000, even 5,000 times.
Look at that. A great forest of carbon nanotubes.
Their great virtue is that you can make almost any shape you want.
So you can grow a forest.
It increases the conductive surface area
and makes them very useful for electronic applications.
The potential applications for this stuff are vast.
Its conductivity and lightness will mean that it will replace copper,
and it could carry several hundred times the current.
Because it's the strongest material known to man,
people are even talking about building an elevator into space with it.
The space elevator is an idea
that's been around for over 100 years,
but now it's left the pages of Jules Verne and become a real possibility.
The aim would be to create a cable to link Earth to a space satellite.
An elevator would then run up the cable, like a train on rails.
It would extend 22,000 miles into space
and a further 40,000 to a counterbalance to stabilise the structure.
But with production at 12 miles a day, there's a long way to go.
Imagine one day you could build a giant solar power station in space,
and think how much clean energy you could send back to Earth.
HAWKING: In the last 60 or 70 years, we have learned much about
the extraordinary workings of the universe around us, and within us.
But there are still great essential mysteries to be solved,
questions we ask ourselves
about how the universe works and the future of mankind.
In a few days, I'm planning to visit Stephen Hawking,
to ask him what he thinks of some of the big puzzles that face us all,
and find out what he'd like to ask me.
For me, the essence of what scientists do is not maths or experiments,
abstract thought or even applying for research funding,
but asking questions.
Newton wanted to know why things fell to the ground.
Darwin, why animals were different in different places.
I'm on my way to talk to Stephen Hawking
about some of the questions we are both still asking.
I want to ask him his views on evolution. As a physicist,
does he think that the origin of life on Earth is just a happy coincidence?
The existence of the Earth,
and the properties that made it possible for biological life to develop,
depend on a very fine balance between the so-called constants of nature.
If they were more than slightly different,
either planets like the Earth would not occur,
or the chemical processes necessary for life would not take place.
One might take this as evidence for a divine creator,
but an alternative explanation is what is known as the multiverse.
The idea is that there are many possible universes.
Only in the small number of universes that are suitable
will intelligent beings develop,
and be able to ask the question, "Why is the universe so carefully designed?"
DAWKINS: What happened before the Big Bang?
What happened before the origin of space and time?
HAWKING: In Newton's theory, time was separate from space,
and ran from the infinite past to the infinite future.
However, Newton's theory
was superseded by Einstein's general theory of relativity.
This allowed the beginning of the universe to be like the South Pole,
with degrees of latitude playing the role of time.
Asking for a time before the beginning
would be like asking for a point south of the South Pole.
Can one assume that insects and bacteria will survive us
if our so-called intelligence leads us to destroy ourselves
by nuclear war or other disasters?
Yes, I think you've got an excellent point.
We happen to survive by our intelligence
and so we think that's the way you should survive.
But from a bird's point of view, say a swift,
they would think that flying is the way you survive.
Eyes are said to have evolved some 40 times, independently.
Flight has evolved four times independently.
But it looks as though intelligence, at least verbal intelligence of our kind,
has only evolved once,
and so that might suggest that it's a pretty esoteric way of surviving.
It seems to work very well for us, of course,
and we're doing very well, we're overpopulating the planet with it,
but if we go too far with it and destroy ourselves and destroy much of life,
then of course you are right that other ways of survival will take over,
bacteria prominent among them.
HAWKING: One can't help asking.
Why are you so obsessed with God?
Well, I notice that you brought up the question of God and I didn't.
When you ended A Brief History of Time
with "for then we shall know the mind of God",
I suspect that you were using God in a sort of Einsteinian sense,
a euphemism for the mystery at the root of the universe,
that which we don't understand, but most people use the word God for a person.
God as an answer to scientific questions.
Then I think it is scientifically pernicious
because it distracts people away from the hard work
of answering scientific questions.
It's just too easy to say, "Oh, God did it,
"therefore we don't need to answer the question."
Looking to the future, do you think there will be scientific geniuses
in a world of super-computers?
Our picture of the universe has been transformed
by brilliant individuals, like Newton and Einstein,
who have made great leaps in the imagination.
Computers cannot make such leaps,
so I think there will be plenty more Newtons and Einsteins in the future.
Thank you very much indeed.
Thank you.
In the not too distant future,
there are certainly going to be major problems.
Problems about climate change,
problems about increasing density of population.
There will be a problem, too, about power - how are we to generate power?
Science will produce the answer.
What the answer will be, I don't know,
but I am perfectly certain that it is science that will find it for us.
HAWKING: We began this story in the 17th century
at a time of witchcraft and superstition,
when Britain was just recovering from a bloody civil war.
We've seen how a handful of men began by asking questions.
What keeps the stars in the sky?
What makes an apple fall?
What invisible worlds exist on our skin and under our noses?
Their determination and curiosity brought science into being.
AL-KHALILI: In the 350 years since,
British scientists have learnt to picture the enormity of the universe -
and they've split the atom.
DYSON: They discovered how to cross oceans and fly at supersonic speeds,
how to power turbines and light up cities.
DAWKINS: They've uncovered the greatest secrets of life
and shown us just how astonishing the world is.
WINSTON: Scientists have helped us live longer,
healthier and more fulfilled lives than ever before.
ATTENBOROUGH: Above all, these men have changed our world for ever.
Indeed, they've made it what it is.
DYSON: They were often awkward and contentious characters -
people who kept on asking questions and didn't settle for second-rate answers.
AL-KHALILI: Their stories explain why science is so important to us.
SYKES: You don't have to be the cleverest kid in class
or go to a posh school to become a great scientist.
ATTENBOROUGH: What is clear is that we need more men and women
like them in the future, not fewer.
HAWKING: We hope that some of you watching now will take up this challenge
and continue to ask the important questions.