Secrets of the Universe: Great Scientists in Their Own Words

The 20th century witnessed an astonishing revolution in physics.

From unlocking the secrets of the atom...

..to working out the origins of the universe...

..physics took us places we'd never dreamt possible.

This was also a century when we were for the first time

able to see and hear scientists in their own words.

I began to notice there was something slightly curious on the records.

I didn't take it in, because I was probably daydreaming, and...

I can't stop! I mean, I could talk forever.

So we began to learn not just about the science,

but the men and women behind it.

And the more we learnt about these scientists,

the more it became clear

that their personalities...

eccentricities...

and rivalries...

It was that he was too sure too quickly.

..were all fundamental to their discoveries.

In fact, it's impossible truly to understand

the 20th century revolution in physics

without first knowing who these men and women really were.

I see. And your idea is to find out what nature COULD be.

8:15am.

The 6th August 1945.

Hiroshima.

And the world witnessed the power of physics.

A catastrophic explosion

sent a shock wave that flattened the city...

sparked a huge firestorm

and bathed every living thing in deadly radiation.

Over 60,000 people died immediately.

The atomic bomb shocked the world,

causing a scale of destruction never before witnessed.

It also broke the heart of the world's most famous scientist -

the man who had launched the 20th century revolution in physics,

and dedicated his life to world peace and equality.

Hiroshima devastated Albert Einstein -

not only because it tested his ideals,

but also because he felt he had played a role

in the development of the bomb.

What weighed heaviest on Einstein's conscience

was a letter he had signed in 1939.

It was addressed to the US President, Roosevelt,

and written to encourage the Americans to build the bomb

to deter the Nazis.

Einstein knew that his signature

would have carried more weight than any other.

After all, by then he was the most famous

scientist in the world - a scientific superstar.

Einstein never worked on the Manhattan Project

that built the bomb,

but from the moment he learnt about the death

of tens of thousands of innocent civilians in Hiroshima,

he deeply regretted ever having signed the letter.

Yet there was also another, more fundamental way

in which Hiroshima lay on Einstein's conscience.

Because the equation that made him famous,

the equation that symbolised the scientific revolution he created,

was the very same equation that underpinned the atomic bomb -

E = mc2.

In this simple and beautiful equation,

Einstein had rewritten the laws of physics.

But he had also unwittingly handed the world

the key to the atomic bomb.

It was an outcome he could never have foreseen

when he began his scientific studies at the start of the 20th century.

Einstein had crafted E = mc2 when he was in his 20s.

At the time, he was just a young man working in obscurity

in a patent office in Bern, Switzerland.

But he had a fascination for light, space and time.

He read a lot while he was at the patent office.

He read a lot in the evening and weekends,

and there was an informal group of scientists in Bern.

He was very much engaged in discussion about science,

even though he was spending his time at work assessing patents.

Despite the group, Einstein did his best work alone.

His method was to create thought experiments

that asked some simple, profound questions.

Questions like, "If I'm travelling on a tram,

"does time run differently for me

"inside the tram compared to people standing on the street outside?"

And, "If I was travelling away from a clock tower on a beam of light,

"would my wristwatch and the clock read the same time?"

Whichever area he was looking at,

he would find the little inconsistencies,

the things that didn't quite make sense,

the things that in retrospect seem like a bit of a fudge

when you got different explanations for the same phenomenon.

And he would focus in on those little rough corners

and completely cut them away and bring in something new,

and bring clarity to the situation.

And that was very characteristic, I think,

of the way he operated in all those different fields.

Einstein spent time deep in concentration

considering the outcomes of his thought experiments...

..which would culminate in two ground-breaking theories

that would lay the foundations for modern physics.

First there was his special theory of relativity.

This proposed a radical new concept of space and time,

suggesting that neither are absolutes,

but can change depending on the relative motion

of objects and observers.

A set of ideas that also led to E = mc2.

And then his general theory of relativity,

which gave physicists a new understanding of gravity.

Rather than being a force,

it was now a property of the curvature of space and time.

They were ground-breaking new theories,

products of Einstein's vivid imagination, creativity

and ambition.

The freedom and independence he enjoyed in Bern,

away from the formality of academia, allowed him the space

to formulate some of the most original ideas in science.

And as other scientists began to provide support for these theories,

Einstein was rocketed into world fame.

Einstein had the reputation, before all these results were announced,

of being very mild-mannered, of being shy -

but he absolutely rose to the occasion.

He just basked in the glory, and he really loved it.

And he went on tours and he talked to audiences.

His lectures weren't always very good,

and there's a report from Oxford by a student,

and he said, when Professor Einstein came in,

he was shuffling along and he looked quite dejected and low-spirited,

and then the audience rose to its feet and clapped,

and suddenly Einstein came alive and his whole face lit up -

and he obviously really needed that public adulation.

-MAN:

-Can you kill the lights, fellas?

Can you kill the lights?

Shake hands with me...

The public latched on to Einstein's playful image,

rather than trying to understand his complicated theories.

The intellectual elite treated him like a god.

LAUGHTER

After Einstein,

the story of 20th-century physics

became the story of men and women who either built on Einstein's work,

attacked it, or filled in the gaps of what it could not explain.

And the first big development after relativity

concerned the one part of the universe that seemed to defy it.

The world of the subatomic particle.

This was a strange new world,

and it led to an entirely new branch of physics.

It was called quantum theory,

and became characterised by both bizarre ideas

and rather bizarre people.

Few were more strange than British mathematician Paul Dirac.

His intellect rivalled that of Albert Einstein,

but in character Dirac could not have been more different.

Talking about the history of quantum mechanics,

the English physicist Paul Dirac.

Quantum mechanics was discovered 40 years ago by Heisenberg.

Shortly afterwards it was discovered again,

independently, in a rather different form by Schrodinger.

Heisenberg and Schrodinger gave us a very wonderful theory.

Many people took it up and proceeded to develop it.

I was one of them.

Well, he was certainly a very strange man.

He was very quiet - people call him shy.

I guess he was shy.

He took things very literally.

Also, it might be something that seemed a bit rude.

I know that somebody asked him

whether he had seen any good films recently, or something -

sitting next to him, probably, at High Table,

at St John's College, Cambridge,

and he said, "Well, why do you want to know?"

Dirac would later attribute his silence

to being bullied as a child by his father.

he was brought up by this very strict father

who insisted that at dinner time - or at home, I think -

his son should only speak in French.

And Dirac didn't like to speak in French,

and so, the preferable option, he just didn't speak at all.

Others claimed Dirac's social awkwardness

was because he was autistic.

Whatever the reason,

it didn't hold him back in the pursuit of a career

in mathematics at Cambridge.

Professor Dirac, we heard before from Professor Heisenberg

about his visit to the Kapitza Club in Cambridge.

Can you tell us something about that club?

Kapitza was a young Russian physicist who came to Cambridge

to work with Rutherford.

He organised a club, about 20 members, physicists,

who would meet every Tuesday evening,

and someone would then read a paper on some question of physics,

and there would be a lot of discussion afterwards.

There was a minute book that was kept of this club,

which is very fortunate, and we can look in the records of that

and see just the subject that Heisenberg talked on.

I don't remember whether he spoke about his new theory at that time.

I... If he did, I didn't take it in, because...

I was probably daydreaming,

and I don't take in everything a lecturer says.

Despite his daydreaming,

Dirac was singled out as a brilliant and fresh new talent

in the new field of quantum theory.

He was invited to speak

at the most prestigious international physics event -

the Solvay Conference.

Only a few months later, he published an equation

which would solve one of the biggest problems in physics

and become his most seminal work.

I suppose the thing that Dirac's best known for

is the Dirac equation.

And I remember going to lectures where people would say,

"Well, the Dirac equation

"is the most accurate equation known in science."

I don't know if you'd say that now,

but it's the equation of the electron.

It was partly to solve a problem which people found

that they couldn't describe particles

in accordance with relativity.

Dirac had done what no-one else could.

He had crafted an equation to describe how electrons behave

that was consistent with both quantum theory

and special relativity.

A union that had yet to be proved possible.

It was certainly highly original,

but I think this was driven, maybe,

by the fact that there was a barrier between him and the outside world,

and that he was internally driven

and therefore found that this was the way he understood things,

and he would quite often, therefore, understand things in a different way

from the way other people did, and it might be a better way,

because he'd thought it all through in his own terms.

As well as explaining how electrons behave,

he developed a theory of quantum electrodynamics

which described the interactions between electrons and light.

Dirac's unique understanding of subatomic particles

won him a Nobel prize

and led to a series of breakthroughs in quantum physics.

But despite all of his successes,

Dirac would never become a household name.

Unlike Einstein, attention made him uncomfortable,

so he avoided the limelight whenever he could.

He was interested in other things than science,

but a little bit surprising -

for instance he was interested in cartoon movies,

Mickey Mouse, and things like that.

He was interested in things

where the emotional content was not a major part of it.

But then there was also this story about either a play or a book,

I can't quite remember which now,

by a Russian author - maybe Dostoevsky.

In it, somebody asks him, "Well, what did you make of it?

"Did you enjoy it?"

And he said, "Well, at one point the author made a mistake

"and he said the sun rose twice in the same day."

HE CHUCKLES

So this is the sort of thing he would point out

about some literary classic,

rather than commenting on its emotional impact.

Dirac only ever let a few people into his world.

His wife was the sister of a very distinguish quantum physicist -

or a mathematical physicist, Eugene Wigner,

who was a very important figure, also, in the early days

of quantum mechanics,

and so she must have known that community

and known how Dirac was respected within that community,

which I expect had something to do with their getting together.

And she probably felt that he was somebody who needed protection,

needed attention,

and somebody who would be very worthwhile

and interesting to be with.

While Dirac was developing the foundations of quantum mechanics,

explaining the world of the very small,

other scientists were working at the opposite scale,

exploring the boundaries of the known universe.

General relativity had led to the idea

that we live in an expanding universe,

and observations had confirmed it.

But this led to a fundamental question.

Did the universe have a beginning?

It was a question that would cause

one of the bitterest rivalries in science -

a conflict that consumed two brilliant physicists,

but would ultimately lead us

to a deeper understanding of the universe.

As you probably know, there are two forms of cosmology -

what has been spoken of as the Big Bang, and the Steady State.

The one that I've been associated with...

..the galaxies must be forming the whole time.

Fred Hoyle was the son of a wool merchant,

and brusque Yorkshireman,

who believed that the universe had no beginning and has no end.

In the explosion theory,

we suppose that the matter

in the universe was originally in a highly condensed state

which then expanded.

And the galaxies which we now see are fragments of this explosion.

Martin Ryle was a volatile yet sensitive man

who, unlike Hoyle, believed the universe did have a beginning.

Both worked at Cambridge University.

And in the 1950s, neither man had enough evidence to prove

one way or the other who was right.

-PROFESSOR MARTIN REES:

-I only got to know Fred Hoyle after 1965,

when I was a student,

but I already became aware that he had been a great figure

in the history of the subject.

Indeed between 1945 and 1965 it's fair to say that he contributed more

to astronomy on the theoretical side than anyone else in the world.

He was an extraordinarily inventive and versatile person.

And his greatest achievement, in retrospect, was to realise

that all the atoms that we are made of were forged inside stars.

Hoyle was a confident man whose great achievements were,

in part, because he wasn't afraid to go it alone

FRED HOYLE: One of the things that one has to, um, think about

is you have to have a sense of obstinacy in science.

Because if you don't, you're not going to go against the crowd.

And if you don't go against the crowd,

you're not going to have any real successes.

But the question then is, can it interfere with one's judgment?

Well, um, let me make it absolutely clear

that a sense of obstinacy is only of value

insofar as it allows you to discount the opinions of other humans.

At the time, Hoyle was an atheist.

So perhaps it wasn't surprising

that his Steady State theory avoided any hint of a genesis.

He said that the universe had always looked the same,

that new galaxies formed

in the spaces made by the universe's expansion.

And as a practised populariser of science,

Hoyle took to the airwaves to promote his point of view.

The BBC presents The Nature Of The Universe.

'The speaker is Fred Hoyle -

'a Cambridge mathematician and Fellow of St John's College.'

'Perhaps like me, you grew up with a notion

'that the whole of the matter in the universe

'was created in one big bang at a particular time in the remote past.

'What I'm now going to tell you is that this is wrong.'

EXPLOSION

Hoyle was the first person to refer to the explosion theory

as a "big bang".

EXPLOSIVE RUMBLING

And although he didn't intend it to, the phrase

captured the public's imagination

and became a brilliant marketing tool for his opponents.

Perhaps his greatest opponent was Ryle -

different in almost every way.

Unlike Hoyle he was a practical scientist, an engineer,

who sought to observe the secrets of the universe,

mapping the faintest, furthest things in the universe

with a radio telescope -

the newest and most exciting instrument in astronomy.

MUSIC: Raymond Baxter Reports Theme

-RAYMOND BAXTER:

-'This is Martin Ryle, Fellow of The Royal Society,

'Professor of Radio Astronomy at Cambridge University.'

'We're receiving a naturally emitted radiation,

'just like the light from a star.'

And if we listen to these radio waves,

as in the case of the distant source, in Cygnus,

what we hear is a rushing noise.

WHOOSHING

-PROFESSOR REES:

-Martin Ryle was above all a brilliant technician

and engineer, but also he combined that

with being someone who understood the theory of what he was doing

and the importance of it.

And it's important to realise

that having invested many years of effort

in developing a pioneering new telescope,

and actually built it

and made the effort to get the money for it et cetera,

then, clearly, he had a huge stake

in ensuring that it did important work

and was naturally rather sensitive at criticism of the output.

So when theorist Fred Hoyle publically questioned the accuracy

of the first data set produced by his telescope,

Ryle was devastated.

I think he took criticism rather deeply.

It's partly because of his personality.

Unlike Fred Hoyle, he was not robust in argument -

he got genuinely upset -

and he didn't really like taking part in debate.

He didn't go to many conferences - he didn't enjoy them.

And so he therefore took very deeply any criticism -

it meant a lot to him.

In front of the media,

Ryle was very self-controlled and diplomatic.

But those who knew him well often saw a different side to him.

PROFESSOR CRAIG MACKAY: Martin Ryle did have

a bit of a temper, there's no doubt about it.

He would very easily fly into a rage about something.

And I ended up getting on extremely

well with him by writing down

what my argument was and giving it to him.

I would then get that back after a day or two,

with Biro markings which were often

so fierce as to go right through the paper.

And that would be his view of the whole thing and I would reply.

So we had this correspondence

and it's my great regret that I've kept none of that.

Many of those bits of paper were pretty transparent

after he'd had a go at them.

Ryle's fury with Hoyle fuelled his determination

to use his radio telescope to destroy the Steady State theory.

Can you explain exactly what you've been doing?

Well, I think we'd better have a diagram here.

And perhaps we could look at the board.

According to the theory of continuous creation,

the density of galaxies would be the same

in the neighbourhood of the Earth, here,

right out to the edges of the observable universe.

One way in which one could test the two theories is to make a measurement

of the variation of the density of

galaxies with distance from us.

If the Steady State theory was right then the more distant galaxies,

which are older, would be distributed just as they are now,

because it says the universe has always been the same.

EXPLOSION

If the Big Bang theory was right,

then the more distant galaxies

would be more densely packed,

because the early universe would have been crammed full of matter

before expanding and evolving.

It's very easy for someone in the public to look at this

and think, "It's two astronomers arguing about something."

They're not. They're very different.

A mathematician and an engineer are really rather different animals,

they do look at the universe in a completely different way,

they see different things - that was the fundamental problem, I think.

There was very little attempt on either side,

I believe, to understand the other -

how they worked, how they ticked.

Unlike Ryle, Hoyle was a performer

and wasn't one to keep his opinions to himself.

Do you reject this Big Bang theory?

This concept of a beginning, an evolution and a going on?

Well, I do and I always have done.

One doesn't impress on the universe its properties in the start.

I think my objection to Ryle was he was too sure too quickly.

-PROFESSOR MACKAY:

-Martin Ryle also found it very difficult

with Fred Hoyle being

extremely negative about the work of the group,

but it's also true that Martin Ryle really made

no serious attempt to build bridges with Hoyle and his people.

And I think that that was very unfortunate.

The two groups were working maybe as far as 200yds apart

in the same town - an easy walk from one to the other -

and the contact between the two groups was minimal.

Collecting radio telescope data was a slow process.

But in 1961, Martin Ryle presented a comprehensive catalogue

that showed the furthest observable galaxies

were more densely distributed.

Finally he could settle the matter.

RYLE ON TAPE: 'The first and most remarkable result of all,

'as you proceed outwards

'from the most intense

'and presumably nearest sources,

'we find a great excess of fainter ones.

'The universe must have changed radically within the time span

'accessible to our radio telescopes.

'This result seems to show quite clearly that the Steady State -

'the continuous creation -

'theory of the universe cannot be correct.

'The results imply that the universe is changing with time.'

The rivalry between these two men had finally yielded a result -

evidence for the Big Bang theory.

Most of it comes from a body much larger...

For most astronomers, the proof was now stacked against

Hoyle and his theory.

Although Hoyle himself wouldn't accept it.

You have here in Cambridge Professor Ryle,

who is a radio astronomer and, as I understand it,

he made a study of the radio stars and claims to have proved

your Steady State theory wrong.

I still take the same view today.

I think we cannot know whether there is a contradiction with the theory

until we know exactly what these radio sources are.

BIRDSONG

Even when the rest of the scientific community

embraced the Big Bang theory,

Hoyle refused to join them.

In the early 1970s, Hoyle felt forced out of Cambridge.

He moved to the Cumbrian countryside,

where he pursued his love for science fiction writing.

Tea's ready.

Here, he also had more time to spend with friends.

Including a man who was revolutionising

the other great branch of 20th-century physics -

the quantum world of subatomic particles.

Despite their very different specialisms,

they found they had a lot in common.

'Have you had a moment in a complicated problem,'

where quite suddenly the thing comes into your head

and you're almost sure you've got to be right?

Oh, yes. That's...

-This is great.

-Oh, God, yeah.

Richard Feynman was the ultimate showman,

an American who became everybody's favourite physicist.

# In a spell That old black magic

# That you weave so well... #

He was a brilliant mathematician...

enamoured by the smallest,

most fundamental building blocks of the universe.

# ..Always glad when your eyes meet mine

# That same old tingle That I feel inside... #

Suppose little things behave very differently

than ANYTHING that was big.

The behaviour of things on a small scale is so fantastic,

it's so wonderfully...different.

I get a kick out of thinking...

about these things.

Uh, I can't stop. I mean, I could talk for ever.

He was charismatic, engaging and enthusiastic.

A bongo-playing prankster who approached both life

and science with a sense of playfulness.

Atoms do not behave like weights hanging on a spring

and oscillating,

nor do they behave like miniature representations

of the solar system with little planets going around in orbit.

It behaves like nothing

that you've seen before.

Well, there's one simplification.

At least electrons behave

exactly the same in this respect as photons,

that is they are both screwy - but in exactly the same way.

As a quantum man, Feynman was inspired by the great Paul Dirac.

PROFESSOR ROGER PENROSE: There's this wonderful picture

at the Warsaw conference of Feynman talking to Dirac -

Dirac leaning back and Feynman being very...

very demonstrative. They were very different characters,

completely different characters.

Dirac being this introverted...

afraid to say things

unless they're absolutely right.

Feynman saying anything that comes to his mind -

they usually were right nevertheless.

Despite the differences in their characters,

they were both fascinated by the same things.

In fact Feynman was especially interested in unlocking

a riddle that lay at heart of

Dirac's own work on quantum electrodynamics.

I read Dirac's book and he had these

problems that nobody knew how to solve that were described there.

I couldn't understand the book very well because I wasn't up to it.

But there in the last paragraph

at the end of the book it said,

"Some new ideas are here needed."

And so there I was, "Some new ideas are needed? OK."

So I started to think of new ideas.

Although Dirac's mathematical description

of how electrons and photons interact

was undeniably correct, the equations themselves

confused physicists

because they sometimes produced crazy answers like infinity.

PROFESSOR PENROSE: Feynman went his own route

and he said, "Look we don't have to have all this complicated stuff,

"all these formulas and fancy mathematics.

"Let's get right down to the root of what we're trying to do."

Feynman's confidence, creativity and direct approach led to

a radical solution to Dirac's riddle.

It's like building those houses of cards,

and each of the cards is shaky.

If you forget one of them,

the whole thing collapses again. and you have to build them up again.

Feynman's answer came in the form of diagrams.

Little pictures that represented each step of the equations.

They could be manipulated,

used to simplify the complicated calculations, remove the infinities,

and produce useful answers

to make accurate predictions about the world.

Physicists all over the world started using the diagrams.

Feynman had unlocked the potential of Dirac's electrodynamics.

FANFARE PLAYS

In 1965, Feynman was given the Nobel prize to recognise the impact

of his diagrams, although he wasn't the most grateful receiver of it.

I don't like honours.

I'm appreciated for the work that I did

and the people who appreciate it,

and I notice that other physicists use my work.

I don't NEED anything else,

I don't think there's any sense to anything else.

I don't see that it makes any point that someone in the Swedish Academy

decides that this work is noble enough to receive a prize.

I've already got the prize,

the prize is the pleasure of finding the thing out,

the kick in the discovery,

the observation that other people use it.

Those are the REAL things.

The honours are unreal to me.

For Feynman, the real reward

was communicating his passion

to others, and he was very good at it.

The things that are solid are made of atoms,

which, although they're jiggling, they never get out of place.

If you took one away, the others in the right place pull them back.

You see, it's a perpetual...

check with your friend. "Are you OK?" "Yes."

It's like people marching in a...

It's like the high school band march, OK?

Nobody really knows what they're doing.

They're going like this. It's OK, it holds together.

Students flocked to his lectures and would seek out his company

whenever they could.

I don't want to take this stuff seriously, I think

we should have fun imagining it and not worry about it.

There's no teacher going to ask you questions at the end.

Otherwise it's a horrible subject.

# You gotta have my... #

Feynman's informal approach to science,

and his brilliant creativity, were instrumental in the development

and accessibility of quantum theory in the late-20th century.

YELLS

MUSIC: Spinning Wheel by Blood Sweat & Tears

At the same time as the revolution in quantum physics,

scientists were also making great astronomical finds.

Observations that would provide robust proof of Einstein's theories.

One the most significant discoveries was made in the late '60s,

by an extremely determined young woman

embarking on a career in the field of radio astronomy.

'The new instrument was perhaps the least glamorous telescope

'ever built and it was to be operated full-time by one person,

'a girl.'

Jocelyn Bell Burnell however was not just a girl, she was

a talented scientist who had a lifelong passion for the night sky.

JOCELYN: I went away to boarding school at 13.

My physics teacher that I had, Mr Tillet, was a super teacher.

I could well have had a physics teacher

who took the view that girls couldn't do physics

and what's the point of trying kind of thing.

I'm not sure where I'd have gone then, what I'd have done

but Mr Tillet was quite the opposite.

I went to Glasgow and I was the only woman doing physics

and every time I entered the lecture theatre, as was the tradition,

the guys whistled,

stamped, catcalled, banged their desks.

There was a them and me.

I was rather on my own the whole time.

MUSIC: Come On Everybody by Eddie Cochran

In the early 1960s, Bell Burnell started her PhD as part

of Martin Ryle's radio astronomy group at Cambridge University.

She had found her spiritual home.

It was here that Mr Tillet's inspirational teaching

and Glasgow University's trial by ordeal would start to bear fruit.

The Cambridge Radio Astronomy Group had an interest in distant objects

because they were interested in general

in how the universe had evolved.

But first we had to build the radio telescope, and actually

I spent two of my three years constructing a radio telescope.

She was outside in this muddy field,

literally building things that looked like a very large fence,

with wooden poles and wires strung between them,

and it was quite a hard business.

I think she must have become very, very fit because of all that,

but it was a difficult, physically demanding life that she led

when the telescope was being built.

But it was only once the last cables were connected

that the real work started.

Bell Burnell was in charge of searching

for tiny bright objects far out in the cosmos.

We were actually using this telescope to look for quasars,

because they twinkle, and this thing is specially designed to pick out

twinkling things.

And after we'd been running I suppose about a few months

I began to notice there was something slightly curious on the records.

They came out as paper charts,

and of course on these charts you could see radio sources

and unfortunately you could also see man-made interference.

But there was also something that didn't quite fit either bill -

it wasn't exactly a twinkling radio source

and it wasn't exactly interference either.

Everybody's first reactions were that it must be man-made.

Including Bell Burnell's supervisor Antony Hewish,

who was convinced there had to be a terrestrial explanation

for the anomaly on the paper chart.

We wrote round to all the astronomical observatories in Britain

saying, "Have you had any programme going

"which might possibly cause radio interference?"

But the observatories wrote back with the all clear.

There was nothing obviously interfering with her telescope.

It's very easy when doing research, to try and

brush over those things that don't quite fit into your view of things.

It's much easier and much more convenient

if it sort of fulfils your prejudices.

She didn't do that - she found this thing that didn't really make sense,

and she kept at it and was concerned

as it became more and more obvious

that it wasn't making any conventional sense.

So I think that approach was very important.

Bell Burnell enlisted the help of another radio telescope,

to prove to all her doubters that the signal

was in fact coming from the cosmos.

She finally convinced Hewish

that this was something to pay attention to.

The big mystery was:

what in the universe could be producing this signal?

It looked like a series of equally spaced pulses.

I don't know what I had expected

but I certainly didn't expect regular pulsations.

Stars and galaxies don't pulse like that.

Hewish ruled out the possibility that it was

coming from an object,

because it pulsed too regularly and quickly

for any known star or galaxy.

Which led them to consider another explanation.

Second reactions not really voiced very loud were:

perhaps it's little green men?

While the leaders of the radio astronomy group

started considering their response to alien communication,

Bell Burnell remained unconvinced, and returned to her telescope.

She was very self-contained, very self-motivated,

somebody who kept herself to herself.

Wasn't really a great socialite in the group.

Not that my memory is that it was particularly a social group,

there were people who would get together -

but she was somebody who tended to be and preferred to be on her own.

Sometimes in research you can know too much,

and it's the youngster who's ignorant

or somebody coming in from outside

that says, you know, the emperor has no clothes on,

that actually is telling the truth, can see the truth.

I think in order to make scientific discoveries,

you really have to be open to the possibility of something

quite unexpected.

Jocelyn was somebody who WAS open to that,

and she found something quite unexpected.

Bell Burnell was rigorous, keeping meticulous records

and analysing them in painstaking detail.

She was dogged in her pursuit of an explanation.

I was analysing chart from another piece of sky,

and thought I saw a piece of this scruffy kind of signal.

Looked exactly like what I was seeing before

but from a totally different bit of the sky.

Right. I thought, "I'm not going to bed tonight,

"I'm going out to the observatory."

And I switched on the high speed recorder,

in came, blip, blip, blip, blip, blip.

Clearly the same family, the same sort of stuff.

And that was great, that was really sweet.

Now, the people here say that

if they got three signals as exactly spaced as that,

it would be very unusual.

If they got four, it would be phenomenal.

Well, they've had pulses as exactly spaced as that 24 hours of the day

since November.

It was easier with the second one,

and that was a great relief in many ways

because it removed this possibility of it being little green men.

Highly unlikely that several lots of little green men would be

all signalling to us,

all at the same frequency, all at the same time.

With little green men ruled out,

this had to be a brand-new type of cosmological object,

behaving in a way that astronomers had never expected.

The faint blips from space so nearly dismissed as error

took the world by storm.

The new objects were called pulsars, because they pulsed so regularly.

For Bell Burnell, it was a personal vindication

for her years of struggle.

Seeing the article in print was tremendous,

and I remember sending a copy of the paper to my physics teacher.

-INTERVIEWER:

-And that's your physics teacher at The Mount?

At The Mount, yes. My physics teacher at The Mount.

And how did he react to it?

He had actually alerted the school.

There was a lot of publicity.

Mr Tillet had seen this, and told the school.

There aren't so many people that take up physics as a profession,

and certainly relatively few women of my generation,

so Mr Tillet followed with some interest my career.

And I was really pleased that he was still around

at the time of the discovery.

Further investigation showed

that pulsars are the dense remains of rapidly spinning dead stars

that emit beams of radiation.

With each rotation, the beam sweeps

in and out of the Earth's line of sight.

And when they're found in pairs,

they gradually move closer to each other.

This behaviour indicated the existence of gravitational waves -

distortions in space-time produced by massive objects.

It's a phenomenon predicted

by Einstein's theory of general relativity.

It was the strongest evidence yet for the theory

that Einstein had developed

using just the power of maths and abstract thought.

APPLAUSE

'Professor Antony Hewish...'

Antony Hewish won the 1974 Nobel prize

for his role in the discovery of pulsars.

Controversially, Bell Burnell was not included.

But she has remained remarkably philosophical about it.

You can actually do extremely well out of not getting a Nobel prize.

And I have had so many prizes and so many honours

and so many awards,

that actually I think I've had far more fun

than if I'd got a Nobel prize, which is a bit flash in the pan -

you get it, you have a fun week and it's all over,

and nobody gives you anything else after that

cos they feel they can't match it.

But Bell Burnell's discovery not only advanced

our understanding of the universe,

it also forced physicists around the world

to think twice before they dismissed the unconventional.

The scene was now set for other novel ideas in cosmology

to be taken a little more seriously than before.

Good news for another Cambridge PhD student

who was not only pursing an idea rejected by other physicists,

but was also facing his own personal struggle.

In the early 1960s, Stephen Hawking was a normal, beer-swilling student,

living life to the full while his physics studies took a back seat.

However, his life would change for ever

when at the age of 21

Hawking was diagnosed with motor neurone disease.

I was given two and a half years to live.

I have always wondered how they could be so precise about the half.

Its first effect was to depress me.

I seemed to be getting worse fairly rapidly.

There didn't seem any point in doing anything

or working on my PhD,

because I didn't know I would live long enough to finish it.

While he struggled to adjust to the diagnosis,

Hawking fell in love and married a family friend, Jane Wilde.

I certainly wouldn't have managed it without her.

Being engaged to her lifted me out of the slough of despond I was in.

But then things started to improve -

the condition developed more slowly

and I began to make progress in my work.

His spirits were buoyed,

but Hawking believed he didn't have long to live.

Motivated by a sense of his own mortality,

he was determined to complete his PhD at Cambridge.

In it, he applied general relativity to what we see in the universe,

and showed that at the big bang

there had to be what's known as a singularity -

a infinitely small and dense point in space-time.

In the 1960s, it was a thing that most physicists

didn't believe existed.

Roger Penrose was one of his examiners.

He was very good at picking up ideas.

When he came down to London when I was giving a talk -

this was on some cosmological thing -

I remember him particularly asking very awkward questions!

So er...

OK, good questions. I had to think a bit before giving the answer.

So a bit of an awkward cuss, you would say.

Not afraid to bring out issues which

a young student might be a little shy of bringing up,

so he wasn't shy at all in that way.

Hawking remained at Cambridge University,

and his career in astrophysics went from strength to strength.

Although he had outlived his original diagnosis,

his health was inevitably deteriorating.

He could speak for quite a while,

but largely only in ways that

his close colleagues could understand him.

HAWKING SPEAKS INDISTINCTLY

Now, it just so happens that we have the universe here...

INDISTINCT CONTRIBUTION FROM AUDIENCE

-LAUGHTER

-Sorry.

I'd speak to him for a while, and...

A fair amount of to and fro, and I could understand what he was saying

more or less and he could understand what I was saying.

But then he'd say something that... I couldn't understand a word of it.

And he'd spell it out letter by letter.

And it would either be a joke,

-or an invitation to dinner.

-HE LAUGHS

Something which was on a personal nature not technical at all,

so technical things were much easier to understand.

Despite his ailing physical health,

Hawking's mind was sharp and his will strong.

HAWKING SPEAKS INDISTINCTLY

Stephen's lucky in that he chose one of the few fields

in which his disability is not a serious handicap.

HE SPEAKS INDISTINCTLY

Cos most of his work is really just thinking.

HE SPEAKS INDISTINCTLY

And his disabilities don't stop him doing that.

HE SPEAKS INDISTINCTLY

In a way, they give him more TIME to think.

I think probably THE most determined person

I've ever known.

I remember staying at his house

in Little Clarendon Street, wherever it was -

there was a three-storey, little narrow house,

much higher than it was wide.

And when it came to the time when he wanted to go to bed

he would crawl up the stairs -

he refused to have anybody help him in any way -

he would crawl up the stairs, it would

take him about a quarter of an hour to get up the stairs,

put himself to bed, do everything he could for himself.

Hawking's determination was also evident in his science.

Not only had his PhD shown singularities

WERE present in the universe...

..along with Penrose, he proved that they also lay

at the heart of another curiosity - black holes.

Hawking was now used to pushing the boundaries of cosmology.

But his greatest discovery came in 1974,

when he showed that black holes aren't entirely black,

but emit SOME light.

Radiation created by the strange quantum effects

that occur at the edge of the black hole.

Where Dirac had previously managed to unite special relativity

and quantum theory,

Hawking was the first to use both general relativity and quantum

in the same explanation.

Where I have had success,

it has been because I have approached problems from a different angle.

I rely on intuition a great deal.

I try to guess a result.

But I then have to prove it.

That is how I found black holes aren't completely black.

I was trying to prove something else.

There's nothing like the eureka moment

of discovering something that no-one knew before.

I won't compare it to sex - but it lasts longer.

Hawking's unifying idea was revelatory, yet complex.

And having had a family of his own,

he had a burning ambition now to popularize his science.

In 1988, he published A Brief History Of Time,

which aimed to explain the mysteries of the universe

to non-scientists.

It became an international bestseller.

The contrast between his imprisoned body

and a mind roaming the cosmos fascinated the public.

All my life I have been fascinated by the big questions that face us,

and have tried to find scientific answers to them.

Perhaps that's why I have sold more books on physics

than Madonna has on sex.

He was catapulted into celebrity,

and became the most famous living scientist.

He clearly likes his fame -

one can see that this is something

he does get a lot of enjoyment out of,

having big crowds and...

So there's an element of showmanship about it all.

Hawking's strength as a communicator of science

has opened a window onto the cosmos,

and enabled us all to marvel at its glory.

Throughout the 20th century,

the secrets of the universe

have been unravelled by extraordinary individuals.

Inspirational men and women,

who have discovered fundamental new truths...

..about everything from the subatomic

to the extremely massive.

But today, science has changed.

Many of the most exciting frontiers of physics are being explored

not by individuals, but by large groups of scientists,

working together in collaborative units.

The subject now is much more sophisticated,

in that whether you're a space astronomer,

an optical astronomer or a particle theorist,

you depend on very large instruments, at CERN for instance.

You have the designers of the instruments,

the operators of the instruments,

those who analyse the data, the phenomenologists

and the theorists who try to make sense of it at a deeper level.

So the story of physics in the 21st century

is more about collective endeavour.

And although we may miss the individual personalities,

it is a price we may have to pay

if we are to stand a chance of solving

the remaining secrets of the universe.