My name is Patience Thomson, born Bragg.
I was the youngest child of William Lawrence Bragg and the
granddaughter of WH Bragg, whom I just dimly remember.
We have this bust of my father, which
I absolutely love.
It's a very, very good likeness.
It moves and stirs me every time I see it.
William Henry and William Lawrence Bragg were the first
father and son team to win a Nobel Prize for a discovery
that shone a new light on the structure of our world.
And it all started with an x-ray.
Most people know what an x-ray is, or they think of the
shadowy photograph that they've seen of a broken leg
or a broken arm.
So they know that x-rays is a powerful special type of light
and that it can pass through most forms of matter and
certainly can pass through biological tissue.
But it's absorbed by bone, which is
why it leaves a shadow.
In 1912, Max von Laue was firing x-rays at crystal
samples and becoming intrigued by the
patterns that were formed.
But he couldn't make complete sense of what they meant.
WH Bragg showed his son Lawrence
these diffraction patterns.
Well, like everybody else, he saw a pattern of spots.
But I think he also saw a puzzle, and a puzzle that
needed to be solved.
He loved detective stories.
That was his great thing.
One of his great mortifications is that he once
sat next to Agatha Christie at dinner and was introduced by
her married name and didn't realise who she was.
My mother said afterwards, you must have had a marvellous
time sitting next to Agatha Christie.
And he said, what?
OK.
So maybe Lawrence wouldn't have made a great detective.
But when it came to piecing together scientific clues, it
was a different matter.
He just looked at the problem in a completely different way
to Laue, and he saw what the solution was.
He noticed things that other people didn't notice.
Everybody was looking at those Laue x-rays and trying to get
an interpretation.
Typical of my father to see that, in fact, a
two-dimensional sheet could be transformed into a
three-dimensional model.
Ping pong balls and rods.
This is one of the very first diffraction patterns that the
Braggs themselves would have taken.
And it's taken from a crystal of salt.
You can see the very particular pattern.
Each of these spots represents the end of a diffracted ray.
And it was their particular insight that showed us how to
interpret this pattern in terms of the atomic structure
within the crystal.
William Henry had been thinking
of x-rays as particles.
However, Lawrence suddenly had an insight about the nature of
crystals themselves.
So what is it really that makes a thing a crystal?
It's its inside arrangement.
It's the fact that the molecules or atoms in it are
in an absolutely regular pattern, like soldiers on
parade or like the pattern of a wallpaper.
The atoms are arranged in layers or in two-dimensional
planes that go all the way through the crystal.
And so he realised that each one of these acts like a
semi-transparent mirror.
What's happening is that the x-ray is reflecting off the
top layer but also off the next layer underneath and off
the layer underneath that, and the x-rays bounce off those
planes in all sorts of directions.
By thinking of the problem simply as reflection, he was
able to figure out how the atoms were arranged exactly
and produce this model in fact, which is the very first
atomic structure of a crystalline sample that was
ever solved.
He liked to make connections.
He liked always to be building up a
picture increasing insight.
Scientists finally had the ability to look at the atomic
structure of matter.
And they could start to understand some of the
physical properties of matter, in terms of the underlying
atomic structure.
And that was an enormous breakthrough.
He didn't realise probably at that stage how massive the
breakthrough he'd just made had been.
His solution was almost always the simplest.
The same in his watercolours, with the almost professional
ability to bring out the important things.
And the same in his articles.
He would give visual illustrations.
It wasn't tell me.
It was show me.
And it helped to explain why it is that these two forms of
carbon have such different properties.
Diamond is one of the hardest substances that we know of.
And the atomic structure shows that that strength arises
because the atoms are bonded to each other very closely and
in all three directions.
Whereas in graphite, you've got these
close hexagonal nets.
But the whole structure is layered, and they can slide
easy past one another.
Graphite is also a pure form of carbon,
but it's much softer.
That very softness arises from the fact that these layers are
not tightly bonded to one another.
And that was first revealed by x-ray crystallography.
Well, the great, great breakthrough on
crystallography came when he was walking along The Backs in
Cambridge and suddenly had a blinding insight.
But it could be when he was doing the washing up.
He didn't have to be in a rarefied atmosphere to have
these ideas.
You felt that his brain was working all the time and that
he liked to have some problem to crunch on.
The Braggs' work on crystallography was disrupted
during World War I, with Henry moving into submarine
detection and Lawrence being sent to the front line.
But their insights led to a shared Nobel Prize in 1915,
with Lawrence becoming the youngest Nobel winner in
history at just 25.
My father heard that he had won the Nobel Prize when he
was in the trenches.
He was obviously extremely chuffed and pleased, but I
think the world was in such total disarray around him that
it all must have seemed rather remote.
He now turned to using science to fight against the German
Army's superior weaponry.
The German Army had the upper hand very often, because they
had much more powerful guns.
And my father was asked to establish a system of working
out, by listening to the sounds and comparing how long
it took them to get to various different points, exactly
where the location of the guns were.
In the obituaries on my father, it did say that his
team shortened the war, because they, could put the
enemy guns out of action.
Back in peace time, the field of x-ray crystallography went
from strength to strength.
The discoveries by the Braggs and their successors kept
coming, and the technique was used to solve increasingly
complex structures, such as graphite, penicillin, DNA,
and, more recently, whole viruses.
To date, crystallography has been a
feature of 29 Nobel Prizes.
The application of this technique transformed our
understanding of matter in so many different fields, not
just in geology, understanding minerals, but in chemistry
understanding how different chemicals are built up, and
then, finally, brought us into the realm of biology, where we
could figure out how it is that the molecules that exist
within us are coordinated and work together in order to
sustain life.
And these days, it's kind of a shame he's not with us now,
because I think he would just be enormously impressed to see
how the technique has developed even since 1971,
just the size and the scale and ambition of the types of
problems that people are tackling now.
Whole virus particles have been crystallised and solved.
We are simply getting better and better at doing
crystallography.
The Curiosity Rover that NASA sent to Mars last year has got
an x-ray diffraction instrument on the Rover that's
trundling over the surface.
And so it can pick up samples of soil, and it can analyse
the minerals that are in the soil on Mars.
He liked Agatha Christie, I think, because in the last
chapter everything falls into place.
He liked neat endings.
They're still winning Nobel Prizes, and I don't see that
slowing down.