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~ PIERRE ARVAY: Music For Solo Harp

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There are seven basics shapes of crystals
in nature and a multitude of colours.

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The crystals in nature express something
about the atoms that compose them.

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They help to put the atoms into families.

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This is the world of physics in our own century,
and crystals are a first opening into that world.

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~ KHACHATURIAN: Symphony No.2 "The Bell"

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Of all the variety of crystals,
the most modest is common salt.

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And yet it's surely one of the most important.

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This is a small part of the great mine
at Wieliczka,

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near the ancient Polish capital of Cracow.

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Salt has been mined here
for nearly a thousand years.

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The alchemist Paracelsus
may have come this way on his eastern travels.

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He changed the course of alchemy after 1500,

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by insisting that among the elements that
constitute man and nature must be counted salt.

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Salt is essential to life and it's always had
a symbolic quality in all cultures.

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Like the Roman soldiers,
we still say "salary" for what we pay a man -

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though it means "salt money".

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In one respect, Paracelsus was wrong.

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Salt is not an element.

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Salt is a compound of two elements -
sodium and chlorine.

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That's remarkable enough
that a white fizzy metal, like sodium,

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and a yellow poisonous gas like chlorine,

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should finish up by making a stable structure -
common salt.

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But more remarkable is that sodium and chlorine
belong to families.

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For instance,
sodium can certainly be replaced by potassium.

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Potassium chloride.

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And then, similarly, the chlorine can be replaced
by its sister element bromine.

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Sodium bromide.

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And, finally...

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lithium fluoride -

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in which sodium has been replaced by lithium,
chlorine by fluorine,

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and yet all the crystals are indistinguishable.

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What makes these family likenesses
among the elements?

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In the 1860s,
everyone was scratching their heads about that.

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The man who solved the problem
most triumphantly

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was a young Russian
called Dmitri lvanovich Mendeleev,

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who visited the salt mine
here at Wieliczka in 1859.

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He was 25 then.

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A brilliant young man.

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The youngest of a vast family
of at least 14 children.

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The darling of his widowed mother,
who drove him through science.

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What distinguished Mendeleev was not only
genius, but a passion for the elements.

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They became his personal friends.

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He knew every quirk and detail
of their behaviour.

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The elements, of course, were distinguished
each by only one basic property -

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that which John Dalton had posed originally.

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Each element
has a characteristic atomic weight.

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How do the properties that make them
alike or different flow from that single gift?

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Mendeleev worked at this.

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He wrote the elements out on cards,

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he shuffled the cards
in a game that his friends used to call Patience,

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and that is the game that I shall play again.

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Mendeleev wrote on his cards
the atoms in the order of atomic weights.

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Hydrogen he didn 't really know what to do with.

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So it's lithium, the lightest that he knew,

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then beryllium,

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then boron,

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then come carbon, nitrogen, oxygen,

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and then fluorine.

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The next is sodium.

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And since that has a family likeness to lithium,
we start again up there.

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Now, magnesium, aluminium, silicon,
phosphorus, sulphur,

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and now chlorine.

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And sure enough,
chlorine stands in the same row as fluorine.

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And the next is potassium.

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There is potassium, next to lithium, sodium,
potassium... calcium.

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The fact is that the horizontal rows
on this arrangement make sense.

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They put families together.

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If we arrange in order of atomic weight, get
every one, two, three, four, five, six, seven steps,

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we start afresh,
then we get family arrangements.

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And then the first problem.

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Because, you see,
Mendeleev didn 't have all the elements.

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63 out of a total of 92 were known, so
sooner or later he was bound to come to gaps.

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And the first gap he came to was there

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because the next known element,
namely titanium,

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simply doesn 't have the properties
that would fit it there, with boron and aluminium.

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So he said, "There's a missing element there.
Titanium belongs here."

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And indeed it does, with carbon and silicon.

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Well, I won 't go on,
except just to say that when you go down,

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this is where bromine would come
in this family likeness.

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There were a number of gaps
and Mendeleev singled out three.

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They stand in these three places.

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The one that I've just pointed to...
one here in the same row... and one here.

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And of them he prophesied that on discovery,
they would be found -

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not only that they would have the weights
that fit into their vertical place,

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but that they would have these properties.

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For instance, this most famous -

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what he called eka-silicon -

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he predicted the properties of
with great exactitude.

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It was nearly 20 years before it was found.

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It was found in Germany
and called not after Mendeleev but germanium.

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Mendeleev had predicted that it would be
5.5 times heavier than water. That was right.

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He predicted that its oxide would be
4.7 times heavier than water. That was right.

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These forecasts made Mendeleev famous -
everywhere except in Russia.

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He was not a prophet there
because the tsar did not like his liberal politics.

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The later discovery
of a whole new row of elements

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beginning with helium, neon, argon -

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enlarged his triumph.

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The underlying pattern of the atoms
was numerical, that was clear.

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And yet that can 't be the whole story.

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We must be missing something.

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It simply does not make sense to believe
that all the properties of the elements

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are contained in one number -
the atomic weight.

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Which hides what?

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It must hide some internal structure,
some way the atom is physically put together,

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which generates those properties.

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But, of course, as an idea, that's inconceivable,

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so long as it's believed
that the atom is indivisible.

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And that's why the turning point comes in 1897

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when JJ Thomson in Cambridge
discovers the electron.

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Yes, the atom has constituent parts.

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The electron is a tiny part of the mass,
but a real part,

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and it carries a single electric charge,

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and each element is characterised
by the number of electrons in its atoms.

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And their number is exactly equal
to the number of the place in Mendeleev's table

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that that element occupies.

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The picture has shifted
from atomic weight to atomic number.

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And that means, essentially, to atomic structure.

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Physics becomes, in those years,

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the greatest collective work of science.

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No - more than that.

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The great collective work of art
of the 20th century.

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~ MESSIAEN: Works For Organ

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I say work of art because the notion
that there's an underlying structure,

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a world within the world of the atom,

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captures the imagination of artists at once.

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Since the time of Newton 's Opticks,

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painters had been entranced
by the coloured surface of things.

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The 20th century changed that.

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Like the X-ray pictures of Rontgen,
it looked for the bone beneath the skin,

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and for the deeper, solid structure
that builds up from the inside.

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The total form of an object or a body.

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The Cubist painters, for example, are obviously
inspired by the families of crystals.

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They see in them
the shape of a village on a hillside.

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A group of women. This is Pablo Picasso's
famous beginning to Cubist painting.

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A single face.

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The interest has shifted from the skin
and the features, to the underlying geometry.

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The head has been taken apart
into mathematical shapes

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and then put together as a reconstruction,
a recreation from the inside out.

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This new search for the hidden structure
is striking in the painters of northern Europe.

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Franz Marc, for example,
looking at the natural landscape.

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And, a favourite with scientists,
the Cubist, Jean Metzinger.

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There are two clear differences
between a work of art and a scientific paper.

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One is that in the work of art, the painter
is visibly both taking the world to pieces

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and putting it together on the same canvas.

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And the other is that you can watch him thinking
while he's doing it.

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In both these respects,
the scientific paper is often deficient.

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It often is only analytic...

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...and it almost always hides the process
of thought in its impersonal language.

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I have chosen to talk about one of the founder
fathers of 20th-century physics - Niels Bohr -

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who collected pictures
here in his house in Copenhagen in Denmark,

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because in both these respects
he was a consummate artist.

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He had no ready-made answers.

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He used to begin his lecture courses
by saying to his students,

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"Every sentence that I utter should be regarded
by you not as an assertion, but as a question."

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What he questioned
was the structure of the world.

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And the people that he worked with,
when young and when old,

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were others
who were taking the world to pieces,

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thinking it out and putting it together.

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He went first, in his 20s,
to work with Ernest Rutherford,

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who, round about 1910, was the
outstanding experimental physicist in the world.

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Rutherford was then at Manchester,

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and in 1911,
he proposed a new model for the atom.

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He had said the heavy nucleus is at the centre

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and the electrons circle it on paths,

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the way that the planets circle the sun.

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A nice irony of history that, in 300 years,

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the outrageous image
of Copernicus and Newton

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had become the most natural model
for every scientist.

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Nevertheless, there was something wrong
with Rutherford's model.

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The planets as they move in their orbits
lose energy continuously,

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so that year by year, their orbits get smaller -

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a very little smaller,
but, in time, they will fall into the sun.

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If the electrons are exactly like the planets,
then they will fall into the nucleus.

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There must be something to stop the electrons
from losing energy continuously.

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That required a new principle in physics

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which limits the energy
that an electron can give out to fixed values.

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Only so can there be a yardstick, a definite unit
which holds the electrons to orbits of fixed sizes.

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Niels Bohr
discovered the unit he was looking for...

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...in the work that Max Planck
had published in Germany in 1900.

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What Planck had shown, a dozen years earlier,

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is that in a world
in which matter comes in lumps,

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energy must comes in lumps, or quanta, also.

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By hindsight, that does not seem so strange.

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But Planck knew how revolutionary the idea was
the day he had it.

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Because on that day he took his little boy for
one of those professorial walks and said to him,

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"I have had a conception today...

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...as revolutionary and as great
as the kind of thought that Newton had."

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And so it was.

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Now, in a sense, of course,
Bohr's task was easy.

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He had the Rutherford atom in one hand,
he had the quantum in the other.

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What was there so wonderful
about a young man of 27 in 1913

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putting the two together
and making the modern image of the atom?

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Nothing but the wonderful, visible
thought process.

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Nothing but the effort of synthesis.

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And the support of it,
in the one place where it could be found,

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the fingerprint of the atom,

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the spectrum in which its internal behaviour
becomes visible to us looking at it from outside.

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That was Bohr's marvellous idea.

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The inside of the atom is invisible,

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but there is a window in it,
a stained-glass window,

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the spectrum of the atom.

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Each element has its own spectrum.

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For example, hydrogen has three
rather vivid lines in its visible spectrum.

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Bohr explained them as a release of energy

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when the single electron in the hydrogen atom

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jumps from one of the outer orbits
to one of the inner orbits.

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The red line is when the electron
jumps from the third orbit to the second.

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The blue-green line - when the electron
jumps from the fourth orbit to the second.

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The structure of the atom was now
as mathematical as Newton 's universe,

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but it contained the additional principle
of the quantum.

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Niels Bohr had built a world inside the atom

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by going beyond the laws of physics as
they had stood for two centuries after Newton.

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He returned to Copenhagen in triumph.

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00:20:54,720 --> 00:20:56,676
~ CARL NIELSEN: Symphony No.2

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00:21:16,520 --> 00:21:18,750
Denmark was home for him again.

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A new place to work.

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In 1920, they built the Niels Bohr Institute
for him, where it has been ever since.

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It's interesting to trace the steps of confirmation
of Bohr's model of the atom

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because in a way they recapitulate
the life cycle of every scientific theory.

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First, the paper.

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In that,
known results are used to support the model.

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That is to say,
the spectrum of hydrogen in particular...

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...is shown to have lines, long known,

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whose positions correspond
to quantum transitions of the electrons

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00:22:16,880 --> 00:22:18,836
from one orbit to another.

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The next step is to extend
that kind of confirmation to a new phenomenon.

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In this case,
lines in the higher energy X-ray spectrum.

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That work was going on
in Rutherford's laboratory in 1913

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and yielded beautiful results,
exactly confirming what Bohr had predicted.

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The man who did that work was Harry Moseley,

232
00:22:56,120 --> 00:23:02,434
who, like Rupert Brooke,
died, sadly, at Gallipoli in 1915.

233
00:23:03,600 --> 00:23:08,151
His work, like Mendeleev,
suggested some missing elements

234
00:23:08,240 --> 00:23:12,074
and one of them, hafnium,
was discovered in Bohr's laboratory.

235
00:23:14,480 --> 00:23:19,395
And just at this moment, when everything
seems to be going so swimmingly,

236
00:23:20,400 --> 00:23:29,399
we suddenly begin to realise that
the theory is reaching the limits of what it can do.

237
00:23:30,320 --> 00:23:37,396
It begins to develop little cranky weaknesses,
a kind of rheumatic pain.

238
00:23:37,480 --> 00:23:41,473
And then... the crucial realisation...

239
00:23:43,560 --> 00:23:51,717
...that we have not cracked
the real problem of atomic structure at all.

240
00:23:53,560 --> 00:23:55,516
We've cracked the shell.

241
00:23:56,720 --> 00:24:04,070
But within that shell,
the atom is an egg with a yolk - the nucleus -

242
00:24:05,240 --> 00:24:10,314
and we have not begun to understand
the nucleus.

243
00:24:11,440 --> 00:24:13,396
~ CARL NIELSEN: Serenata In Vano

244
00:24:27,360 --> 00:24:31,273
Niels Bohr was a man
with a taste for contemplation and leisure.

245
00:24:33,400 --> 00:24:38,997
When he won the Nobel prize in 1922, he spent
the money on buying a house in the country.

246
00:24:40,000 --> 00:24:43,197
His taste for the arts also ran to poetry.

247
00:24:43,280 --> 00:24:49,674
He said to Heisenberg, "When it comes to
atoms, language can be used only as poetry.

248
00:24:50,560 --> 00:24:58,148
The poet, too, is not nearly so concerned
with describing facts as with creating images."

249
00:24:58,240 --> 00:25:00,549
That's an unexpected thought.

250
00:25:00,640 --> 00:25:07,159
When it comes to atoms, language
is not describing facts, but creating images.

251
00:25:08,640 --> 00:25:13,077
But it is so. What lies below the visible world
is always imaginary.

252
00:25:13,840 --> 00:25:15,751
A play of images.

253
00:25:15,840 --> 00:25:21,597
There is no other way to talk about the invisible,
in nature, in art or in science.

254
00:25:33,360 --> 00:25:36,477
When we step through the gateway of the atom,

255
00:25:36,560 --> 00:25:39,791
we are in a world
which our senses cannot experience.

256
00:25:39,880 --> 00:25:41,836
~ SIBELIUS: Symphony No.6 in D Minor

257
00:25:44,400 --> 00:25:50,475
There's a new architecture there, a way that
things are put together which we cannot know.

258
00:25:52,680 --> 00:25:58,277
We only try to picture it by analogy,
a new act of imagination.

259
00:26:01,960 --> 00:26:05,999
The architectural images
come from the concrete world of our senses

260
00:26:06,080 --> 00:26:09,868
because that's the only world
that words describe.

261
00:26:10,760 --> 00:26:16,039
But all our ways of picturing the invisible
are metaphors, likenesses,

262
00:26:16,120 --> 00:26:20,671
that we snatch from the larger world
of eye and ear and touch.

263
00:26:22,040 --> 00:26:27,160
Once we've discovered that the atoms
are not the ultimate building blocks of matter,

264
00:26:27,240 --> 00:26:33,236
we can only try to make models
of how the building blocks link and act together.

265
00:26:36,920 --> 00:26:41,516
The models are meant to show, by analogy,
how matter is built up.

266
00:26:41,600 --> 00:26:45,513
So, to test the models,
we have to take matter to pieces...

267
00:26:50,440 --> 00:26:54,319
...like the diamond cleaver
feeling for the structure of the crystal.

268
00:26:55,600 --> 00:26:59,593
The ascent of man
is a richer and richer synthesis.

269
00:27:00,440 --> 00:27:04,991
But each step is an effort of analysis,
of deeper analysis.

270
00:27:05,920 --> 00:27:08,070
When the atom was found to be divisible,

271
00:27:08,160 --> 00:27:11,709
it seemed that it might have an indivisible centre,
the nucleus.

272
00:27:12,440 --> 00:27:17,673
And now it turned out, around 1930,
that the model needed a new refinement.

273
00:27:18,640 --> 00:27:22,679
The nucleus at the centre of the atom
is not the ultimate reality either.

274
00:27:25,760 --> 00:27:30,356
(Machinery roars)
At twilight on the sixth day of Creation,

275
00:27:30,400 --> 00:27:34,359
so say the Hebrew commentators
to the Old Testament,

276
00:27:35,440 --> 00:27:42,198
God made for man a number of tools
that give him also the gift of creation.

277
00:27:43,560 --> 00:27:46,996
If the commentators were alive today,
they would write...

278
00:27:48,040 --> 00:27:50,156
..."God made the neutron."

279
00:27:50,920 --> 00:27:56,552
Here it is,
the blue glow that is the trace of neutrons,

280
00:27:57,360 --> 00:28:03,151
the visible finger of God touching Adam
in Michelangelo's painting

281
00:28:03,240 --> 00:28:06,516
not with breath but with power.

282
00:28:21,120 --> 00:28:23,076
(Thunderclap)

283
00:28:35,320 --> 00:28:39,393
It was James Chadwick who proved in 1932

284
00:28:39,480 --> 00:28:45,589
that the nucleus consists
not only of the electrical positive proton,

285
00:28:45,680 --> 00:28:49,753
but of a non -electrical particle - the neutron.

286
00:28:51,200 --> 00:28:54,510
The neutron, therefore, was a new kind of probe,

287
00:28:55,320 --> 00:28:57,834
a sort of alchemist's flame,

288
00:28:59,040 --> 00:29:01,634
because, having no electric charge,

289
00:29:01,720 --> 00:29:05,759
it could be fired at the nuclei of atoms
and change them.

290
00:29:06,800 --> 00:29:12,432
The modern alchemist, the man who,
more than anyone, took advantage of that,

291
00:29:12,520 --> 00:29:15,353
was Enrico Fermi, in Rome.

292
00:29:18,440 --> 00:29:20,476
Enrico Fermi was a strange creature.

293
00:29:21,440 --> 00:29:27,197
I didn 't know him until much later because in
1934, Rome was in the hands of Mussolini,

294
00:29:27,280 --> 00:29:29,236
Berlin was in the hands of Hitler,

295
00:29:29,320 --> 00:29:31,276
and men like me didn 't travel there.

296
00:29:32,280 --> 00:29:35,795
But when I saw him in New York, much later,

297
00:29:35,880 --> 00:29:39,873
he struck me as the cleverest man
I had ever set eyes on.

298
00:29:41,400 --> 00:29:45,188
Well, perhaps the cleverest man
with one exception.

299
00:29:46,240 --> 00:29:52,679
Compact, small, powerful, penetrating,
very sporty.

300
00:29:53,440 --> 00:29:58,195
And always with the direction
in which he was going

301
00:29:58,280 --> 00:30:03,195
as clear in his mind
as if he could see to the very bottom of things.

302
00:30:04,280 --> 00:30:09,832
The neutrons he used
you can see streaming out of this reactor.

303
00:30:10,800 --> 00:30:17,956
It's a High Flux Isotope Reactor
which has been developed here at Oak Ridge.

304
00:30:21,240 --> 00:30:25,711
Transformation was, of course,
an age-old dream.

305
00:30:26,760 --> 00:30:30,514
But to men like me
with a theoretical bent of mind,

306
00:30:30,600 --> 00:30:38,553
what was most exciting about the period was
that it began to open up the evolution of nature.

307
00:30:39,480 --> 00:30:41,436
I must explain that phrase.

308
00:30:42,520 --> 00:30:46,195
I began by talking about the day of Creation
and I'll do that again.

309
00:30:47,640 --> 00:30:49,596
Where shall I start?

310
00:30:49,680 --> 00:30:58,315
Bishop Ussher, a long time ago,
said that the universe was created in 4004 BC.

311
00:30:58,400 --> 00:31:04,316
Armed as he was with dogma and ignorance,
he brooked no rebuttal.

312
00:31:05,320 --> 00:31:11,953
He knew the year, the date, the day of the week,
the hour, which, fortunately, I've forgotten.

313
00:31:14,120 --> 00:31:18,079
But the puzzle remained, oh, well into the 1900s,

314
00:31:19,160 --> 00:31:25,838
because while it was very clear that the Earth
was many, many millions of years old,

315
00:31:27,160 --> 00:31:30,948
where did the energy come from
in the sun and the stars?

316
00:31:32,440 --> 00:31:34,670
We had Einstein 's equations, of course,

317
00:31:34,760 --> 00:31:38,514
which showed that the loss of matter
would produce energy, by then.

318
00:31:39,280 --> 00:31:41,236
But how was the matter rearranged?

319
00:31:42,240 --> 00:31:47,519
Well, that's really the understanding
that Chadwick's discovery opened.

320
00:31:49,360 --> 00:31:55,674
In 1939, Hans Bethe
for the first time explained...

321
00:31:57,840 --> 00:32:00,195
...in very precise terms...

322
00:32:00,280 --> 00:32:04,478
the transformation of hydrogen to helium
in the sun

323
00:32:04,560 --> 00:32:10,032
by which a loss of mass streams out to us
as this proud gift of energy.

324
00:32:13,360 --> 00:32:16,909
I speak of these matters with a kind of passion

325
00:32:17,000 --> 00:32:22,916
because, of course, to me they have the quality
not of memory but of experience.

326
00:32:23,920 --> 00:32:29,472
Hans Bethe's explanation
is as vivid to me as my own wedding day,

327
00:32:30,640 --> 00:32:34,679
and the subsequent steps that followed,
as the birth of my own children.

328
00:32:35,680 --> 00:32:42,438
Because what was revealed in the years that
followed, and finally sealed in, I suppose, 1956,

329
00:32:43,400 --> 00:32:51,353
is that in all the stars there are going on
processes which build up the atoms one by one,

330
00:32:51,440 --> 00:32:55,228
into more and more complex structures.

331
00:32:56,680 --> 00:32:59,513
Matter itself evolves.

332
00:33:00,680 --> 00:33:03,877
The word comes from Darwin and biology,

333
00:33:03,960 --> 00:33:08,795
but it's the word that changed physics
in my lifetime.

334
00:33:22,560 --> 00:33:28,829
The first step in the evolution of the elements
takes places in young stars such as the sun.

335
00:33:31,280 --> 00:33:36,991
It's the step from hydrogen to helium
and it needs the great heat of the interior.

336
00:33:37,080 --> 00:33:40,959
What we see on the surface
are only storms produced by that action.

337
00:33:46,760 --> 00:33:53,552
Helium was first identified by a spectrum line
during the eclipse of the sun in 1868.

338
00:33:53,640 --> 00:33:57,633
That's why it's called helium.
It was not known on earth until then.

339
00:34:13,760 --> 00:34:21,075
What happens in effect is that from time to time
a pair of nuclei of hydrogen collide and fuse

340
00:34:21,160 --> 00:34:23,116
to make a nucleus of helium.

341
00:34:49,680 --> 00:34:52,638
In time, the sun will become mostly helium.

342
00:34:53,440 --> 00:34:55,954
And then it'll become a hotter star

343
00:34:56,040 --> 00:35:00,318
in which helium nuclei collide
to make heavier atoms in turn.

344
00:35:08,400 --> 00:35:12,279
I've come back briefly to the mine at Wieliczka

345
00:35:12,360 --> 00:35:16,876
because there is a historical contradiction
to be explained here.

346
00:35:18,960 --> 00:35:23,875
The elements
are being built up in the stars constantly.

347
00:35:24,640 --> 00:35:28,349
And yet we used to think
that the universe is running down.

348
00:35:29,440 --> 00:35:31,396
Why? Or how?

349
00:35:33,280 --> 00:35:35,748
The idea that the universe is running down...

350
00:35:36,800 --> 00:35:40,998
...comes from a simple observation
about machines.

351
00:35:56,160 --> 00:36:01,393
Every machine
consumes more energy than it renders.

352
00:36:02,600 --> 00:36:07,116
Some of it is wasted in friction,
some of it is wasted in wear

353
00:36:07,200 --> 00:36:14,515
and, in more sophisticated machines, it's wasted
in other ways in which the energy is degraded.

354
00:36:17,920 --> 00:36:26,191
There is a pool of inaccessible energy into which
some of the energy that we put in always runs.

355
00:36:27,240 --> 00:36:30,869
Rudolf Clausius put that into a basic principle.

356
00:36:31,640 --> 00:36:40,719
He said that there is energy which is available
and there is energy which is not accessible.

357
00:36:40,800 --> 00:36:42,756
That he called entropy.

358
00:36:43,640 --> 00:36:47,428
And he formulated
the famous second law of thermodynamics.

359
00:36:48,360 --> 00:36:50,510
Entropy is always increasing.

360
00:36:50,600 --> 00:36:56,516
In the universe,
heat is draining into a sort of lake of equality

361
00:36:56,600 --> 00:36:58,875
in which it is no longer accessible.

362
00:37:01,200 --> 00:37:07,230
That was a nice idea a hundred years ago
because then heat was thought of as a fluid.

363
00:37:09,240 --> 00:37:16,032
But heat is not material any more than fire is
or any more than life is.

364
00:37:16,800 --> 00:37:20,270
Heat is a random motion of the atoms.

365
00:37:21,240 --> 00:37:27,952
And it was Ludwig Boltzmann in Austria
who brilliantly seized on that idea

366
00:37:28,040 --> 00:37:35,594
to give a new interpretation to what happens in
this machine or a steam engine or the universe.

367
00:37:37,680 --> 00:37:42,595
When energy is degraded, said Boltzmann,

368
00:37:42,680 --> 00:37:46,719
it is the atoms that assume
a more disorderly state

369
00:37:46,800 --> 00:37:50,475
and entropy is a measure of disorder.

370
00:37:51,920 --> 00:37:58,155
It is the probability of the state.
He put that quite precisely.

371
00:37:58,240 --> 00:38:04,634
S, the entropy, is to be represented
as proportional to the logarithm of W,

372
00:38:04,720 --> 00:38:07,598
the probability of a given state.

373
00:38:09,080 --> 00:38:14,200
Of course, disorderly states
are much more probable than orderly states.

374
00:38:14,280 --> 00:38:19,149
So, by and large,
any orderly arrangement will run down.

375
00:38:20,120 --> 00:38:24,238
But by and large is not always.

376
00:38:25,400 --> 00:38:30,758
It is not true that orderly states
constantly run down to disorder.

377
00:38:32,720 --> 00:38:38,829
It is a statistical law,
which means that order will tend to vanish.

378
00:38:39,720 --> 00:38:44,396
But statistics do not say always.

379
00:38:45,120 --> 00:38:49,830
Statistics allow order to be built up
in some islands of the universe -

380
00:38:49,920 --> 00:38:56,234
here on earth, in you, in me... and in the stars,
in all sorts of places -

381
00:38:56,320 --> 00:38:59,073
while disorder takes over in others.

382
00:39:01,840 --> 00:39:03,796
That's a beautiful conception.

383
00:39:05,600 --> 00:39:08,751
But there is still one question to be asked.

384
00:39:10,840 --> 00:39:20,715
If it's true that... probability has brought us here,

385
00:39:23,720 --> 00:39:29,272
is not the probability so low
that we have no right to be here?

386
00:39:30,480 --> 00:39:33,552
People who ask that question,
always put it in this way:

387
00:39:34,320 --> 00:39:37,676
Think of all the atoms that make up my body
at this moment.

388
00:39:39,360 --> 00:39:45,993
How madly improbable that they should
come to this place at this instance and form me.

389
00:39:47,000 --> 00:39:48,797
Yes, indeed.

390
00:39:48,880 --> 00:39:54,477
If that was how it happened, it would not only be
improbable, I would be virtually impossible.

391
00:39:56,040 --> 00:39:58,474
But, of course, that's not how nature works.

392
00:40:00,480 --> 00:40:03,074
Nature works by steps

393
00:40:03,160 --> 00:40:11,317
The atoms form molecules, the molecules
form bases, the bases form amino acids,

394
00:40:11,400 --> 00:40:15,313
they form proteins, proteins work in cells,

395
00:40:15,400 --> 00:40:19,837
the cells make, first of all, very simple animals
and then sophisticated ones -

396
00:40:19,920 --> 00:40:21,797
climbing step by step.

397
00:40:22,560 --> 00:40:29,557
Evolution is the climbing of a ladder
from simple to complex by steps,

398
00:40:29,640 --> 00:40:32,029
each of which is stable in itself.

399
00:40:32,120 --> 00:40:35,351
Since this is very much my subject,
I have a name for it.

400
00:40:35,440 --> 00:40:38,159
I call it stratified stability.

401
00:40:40,160 --> 00:40:49,319
That is what has brought life, not only here, but
constantly up a ladder of increasing complexity,

402
00:40:49,400 --> 00:40:52,119
which is the central problem of evolution.

403
00:40:52,200 --> 00:40:56,352
And now we know that that's true
not only of life but of matter.

404
00:40:58,040 --> 00:41:02,477
If the stars had to build
a heavy element like iron,

405
00:41:03,120 --> 00:41:05,156
a superheavy element like uranium,

406
00:41:05,240 --> 00:41:08,038
by the instant assembly of all the parts,

407
00:41:08,120 --> 00:41:10,714
it would be virtually impossible.

408
00:41:10,800 --> 00:41:15,749
No, no. A star builds hydrogen to helium.

409
00:41:16,960 --> 00:41:21,238
Then, at another stage, in a different star,

410
00:41:21,320 --> 00:41:25,632
helium is assembled to carbon, to oxygen,
to heavier elements

411
00:41:25,720 --> 00:41:33,149
and so step by step up the whole ladder
to make the 92 elements in nature.

412
00:41:34,080 --> 00:41:36,036
~ SIBELIUS: Symphony No.7 in C Major

413
00:41:39,040 --> 00:41:42,476
We can 't copy the processes in the stars
as a whole

414
00:41:42,560 --> 00:41:46,030
because we don 't command
the immense temperatures

415
00:41:46,120 --> 00:41:48,190
that are needed to fuse most elements.

416
00:41:49,080 --> 00:41:54,871
But we've begun to put our foot on the ladder,
to copy the first step from hydrogen to helium.

417
00:41:55,760 --> 00:42:00,754
This is another part of Oak Ridge
where the fusion of hydrogen is attempted.

418
00:42:12,680 --> 00:42:16,639
It's hard to recreate the temperature
within the sun, of course -

419
00:42:16,720 --> 00:42:18,790
over ten million degrees centigrade -

420
00:42:19,520 --> 00:42:25,675
and it's still harder to make any kind of container
that will survive that temperature and trap it,

421
00:42:25,760 --> 00:42:27,716
even for a fraction of a second.

422
00:42:27,800 --> 00:42:30,951
This is a new kind of physics - plasma physics.

423
00:42:31,720 --> 00:42:37,556
Its excitement, yes, and its importance
is that it's the physics of nature.

424
00:42:38,320 --> 00:42:44,668
For once, the rearrangements that man makes
run, not against the direction of nature,

425
00:42:44,760 --> 00:42:50,630
but along the same steps which nature herself
takes in the sun and in the stars.

426
00:42:56,560 --> 00:43:03,318
Immortality and mortality is the contrast
on which I end this essay.

427
00:43:05,840 --> 00:43:11,836
Physics in the 20th century is an immortal work.

428
00:43:12,760 --> 00:43:17,356
The human imagination working communally...

429
00:43:18,440 --> 00:43:20,829
...has produced no monuments to equal it -

430
00:43:20,920 --> 00:43:25,675
not the pyramids, not the lliad, not the ballads,
not the cathedrals.

431
00:43:27,760 --> 00:43:30,832
The men who made these conceptions,
one after another,

432
00:43:30,920 --> 00:43:34,037
are the pioneering heroes of our age.

433
00:43:35,160 --> 00:43:37,310
Mendeleev shuffling his cards.

434
00:43:38,080 --> 00:43:43,473
JJ Thomson, who overturned the Greek belief
that the atom in indivisible.

435
00:43:44,240 --> 00:43:47,789
Rutherford,
who turned it into a planetary system.

436
00:43:47,880 --> 00:43:50,713
And Niels Bohr, who made that model work.

437
00:43:51,760 --> 00:43:53,876
Chadwick, who discovered the neutron.

438
00:43:54,640 --> 00:43:58,918
And Fermi, who used it to open up
and to transform the nucleus.

439
00:43:59,680 --> 00:44:05,869
And, at the head of them, the iconoclasts.
The first founders of the new conceptions.

440
00:44:07,040 --> 00:44:11,830
Max Planck, who gave energy
an atomic character like matter.

441
00:44:12,640 --> 00:44:16,952
And Ludwig Boltzmann,
to whom more than anyone else

442
00:44:17,040 --> 00:44:22,114
we owe the fact that the atom
is as real to us now as our own world.

443
00:44:25,120 --> 00:44:31,992
Who would think that only in 1900
people were battling,

444
00:44:34,400 --> 00:44:36,356
one might say to the death,

445
00:44:37,400 --> 00:44:39,356
whether atoms were real or not?

446
00:44:40,240 --> 00:44:45,394
The great philosopher, Ernst Mach,
here in Vienna where I am, said no.

447
00:44:47,440 --> 00:44:50,193
The great chemist, Wilhelm Ostwald, said no.

448
00:44:51,400 --> 00:44:57,714
And only one man...
at that critical turn of the century,

449
00:44:58,760 --> 00:45:00,796
stood up for the reality of atoms.

450
00:45:01,640 --> 00:45:03,949
He was Ludwig Boltzmann...

451
00:45:05,080 --> 00:45:08,277
...at whose memorial
I have come to pay homage.

452
00:45:12,280 --> 00:45:16,558
An irascible, extraordinary, difficult man.

453
00:45:16,640 --> 00:45:18,596
An early follower of Darwin.

454
00:45:19,680 --> 00:45:23,753
Quarrelsome and delightful
and everything that a human being should be.

455
00:45:30,040 --> 00:45:37,230
The ascent of man teetered
on a real intellectual balance at that point...

456
00:45:38,720 --> 00:45:43,714
...because had anti-atomic doctrines
then really won the day...

457
00:45:46,200 --> 00:45:50,955
...our advance would certainly have been set
back by decades and perhaps a hundred years.

458
00:45:51,040 --> 00:45:55,511
And not only in physics, but in biology,
which is crucially dependent on that.

459
00:45:58,280 --> 00:46:00,350
Did Boltzmann just argue? No.

460
00:46:02,160 --> 00:46:05,869
He lived and died that passion.

461
00:46:06,840 --> 00:46:12,392
In 1906, at the age of 62,
feeling isolated and defeated,

462
00:46:12,480 --> 00:46:15,677
at the very moment when atomic doctrine
was going to win,

463
00:46:15,760 --> 00:46:20,311
he thought all was lost...
and he committed suicide.

464
00:46:23,120 --> 00:46:27,796
What remains to commemorate him
is his immortal formula...

465
00:46:32,480 --> 00:46:34,550
I have no phrase to match Boltzmann 's.

466
00:46:35,800 --> 00:46:40,396
But I will take a quotation
from the poet William Blake...

467
00:46:43,440 --> 00:46:48,275
...who begins the Auguries Of Innocence
with four lines.

468
00:46:50,840 --> 00:46:53,354
"To see a world in a grain of sand

469
00:46:53,440 --> 00:46:55,396
And a heaven in a wild flower,

470
00:46:56,320 --> 00:47:00,393
Hold infinity in the palm of your hand

471
00:47:01,600 --> 00:47:03,716
And eternity in an hour."

472
00:47:03,800 --> 00:47:05,756
~ SIBELIUS: Symphony No.7