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We live on one level of existence,
but there are others.
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These hidden dimensions of
reality are everywhere.
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Far away, across the light years.
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Beneath our feet.
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And even inside you and me.
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We are made of atoms.
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There are more atoms in your eye,
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than there are stars and all
the galaxies of the known universe.
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The same is true of any solid object
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larger than the tip of your little finger.
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I'm a collection of three
billion, billion, billion
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intricately arranged atoms
called Neil Degrasse Tyson.
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You are a similar collection
with a different name.
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We don't usually think
of ourselves this way
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because that level of reality lies
beyond the realm of our senses.
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But we're not gonna let that stop us.
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We can go deeper into the wonder.
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"Deeper, Deeper, Deeper Still"
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Atoms let matter
do funny things.
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To understand water, you need to
know what its atoms are doing.
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Every molecule of water is composed
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of two tiny hydrogen atoms
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attached to a larger oxygen atom.
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That's why we call it H20.
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If it's not too hot or too cold,
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the molecules can slide
and tumble past each other.
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There's still some stickiness
between the molecules,
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but not enough to lock them
into a rigid solid.
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That's what makes something a liquid.
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The sun warms the water.
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And with more energy,
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the molecules move faster.
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That's all that temperature is.
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Those molecules are moving fast enough
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to break the weak bonds that
hold them to their neighbors.
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That's evaporation.
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The air we breathe is made of
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nitrogen and oxygen molecules
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with a scattering of water
vapor and carbon dioxide.
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Incoming!
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That's condensation.
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A dewdrop is the momentary triumph
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of condensation over evaporation.
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And while it lasts,
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it's a little cosmos with its own worlds...
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creatures, drama.
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To explore the far-flung realms
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of this dewdrop,
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we're gonna need a ship.
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One with twin engines...
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science and imagination.
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That's a single-celled paramecium,
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one of a multitude
of skilled hunter-warriors
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that roam the dewdrop.
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But they, too, are hunted.
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The Dileptus. The paramecium's
mortal enemy.
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The paramecium might get lucky
and score a direct hit.
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Even if it doesn't,
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the recoil from the barrage
will put some distance
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between the paramecium and its attacker.
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What can I say?
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That's life in the dewdrop.
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That little guy is tardigrade,
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an animal smaller than the head of a pin.
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Don't underestimate them.
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Tardigrades have been living on this planet
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a lot longer than we have.
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About 500 million years.
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For every one of us,
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there's at least a billion of them.
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They can make a living anywhere on earth.
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In the frigid peaks
of the tallest mountains,
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in the cauldrons of erupting volcanoes,
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and in the deep ocean vents
at the bottom of the sea.
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Tardigrades are so tough,
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they can survive naked
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in the vacuum of space.
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They've survived all five
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of the most recent mass
extinctions on this planet.
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A visitor from another
world could be forgiven
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for thinking of earth as
the planet of the tardigrades.
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If we're ever gonna get
to the bottom of this dewdrop,
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better get a move on.
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Every leaf and tiny clump of moss
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has hundreds of thousands
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of microscopic mouths called Stomata.
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Plants breathe through them,
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taking in carbon dioxide
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and exhaling the oxygen
that we need to live.
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The plants can survive without us.
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But we and all the other animals...
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we'd be toast without them.
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The plants make food out of sunlight.
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We animals can't do that.
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To see how they do it,
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we have to go deeper,
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make ourselves
about a thousand times smaller
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to get into their treasure house,
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the place where they keep the good stuff...
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the chlorophyll.
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That's the molecule
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that converts sunlight into energy.
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Every one of those rectangles
is a plant cell.
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And those tiny green vehicles
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are its energy factories.
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If we could steal their trade secrets,
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it would trigger
a new industrial revolution.
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But to spy on them,
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we're gonna need to go deeper still.
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What alien world
has the ship of the imagination
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carried us to this time?
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It's the cosmos...
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Contained within a dewdrop.
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We're on an industrial espionage mission.
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If we can penetrate the trade secrets
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of the manufacturing process
in that chloroplast,
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let's just say our whole future
hangs in the balance.
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This chloroplast is using sunlight
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to break water molecules
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into atoms of hydrogen and oxygen.
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It combines the hydrogen
with carbon dioxide
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to make sugar,
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and releases the oxygen as a waste product.
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To see how it happens,
we have to go even deeper,
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get even smaller.
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We're talking atomic scale.
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Bingo.
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This assembly line is the heart
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of the molecular industrial complex.
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At the molecular level,
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things happen too fast for us to see.
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So we'll have to slow them down
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about a billion times.
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Those larger molecules are carbon dioxide.
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Each one of them is made
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of one carbon and two oxygen atoms.
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When sunlight strikes a green
molecule of chlorophyll,
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it sets in motion a series
of chemical reactions,
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breaking apart water molecules
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and freeing energetic electrons.
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And that's just the day shift,
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when sunlight supplies
the incoming stream of energy.
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There's a second shift
that works day and night
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using the solar energy kept in reserve.
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The energy of the free
electrons is put to work,
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combining carbon dioxide with
hydrogen from the water.
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The end product is sugar,
which stores the solar energy.
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The chloroplast is a three-billion-year-old
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solar energy collector.
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This sub-microscopic solar battery
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is what drives all the forests
and the fields
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and the plankton of the seas.
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And the animals.
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Including us.
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The solar-powered biosphere
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collects and processes six times more power
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than our entire civilization.
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We understand on a chemical level
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how photosynthesis works.
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We can recreate the process
in a laboratory.
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But we're not as good at it as plants are.
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And it's not surprising,
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considering nature has been at
this for billions of years,
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and we've only just started.
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But if we could figure out
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the trade secrets of photosynthesis,
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every of other source of energy
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we depend on today...
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coal, oil, natural gas...
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would become obsolete.
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Photosynthesis is the ultimate green power.
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It doesn't pollute the air
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and is, in fact, carbon neutral.
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Artificial photosynthesis
on a big enough scale
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could reduce the greenhouse effect
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that's driving climate change
in a dangerous direction.
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Uh-oh, place is evaporating.
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Time to get out of here.
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How fleeting is the life of a dewdrop.
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It condenses from thin air
in the cool of the night,
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only to vanish with the heat of the day.
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And what of its inhabitants,
the tardigrades?
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They'll be fine.
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They can go without water for years.
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It's hard to imagine,
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but plants covered the surface of the earth
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for hundreds of millions of years
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before they put forth their first flower.
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That was about a hundred million years ago,
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shortly before the dinosaurs
were wiped out.
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Our world must've been a relatively
drab-looking place back then,
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dominated by shades of green and brown.
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Yeah, there were giant trees
and ferns and other plant life,
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but not the purple of an iris
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or the crimson of a red, red rose.
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Orchids were among
the first flowering species
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to appear on earth,
and they're the most diverse.
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Darwin was particularly fascinated
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by the comet orchid of Madagascar,
200
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a flower whose pollen is hidden
at the bottom
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of a very long, thin spur.
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There can be no stronger test of an idea
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than its predictive power.
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On the basis of his theory of evolution
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through natural selection,
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Darwin speculated that somewhere
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on the island of Madagascar,
there must live flying insects
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with extraordinarily lengthy tongues,
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ones long enough to reach the pollen.
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No one had ever seen such a beast there,
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but Darwin insisted
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that an animal fitting this
description must exist.
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Few people at the time believed him.
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It wasn't until more than 50 years later
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00:12:01,146 --> 00:12:03,447
that Darwin was proven right.
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00:12:03,481 --> 00:12:09,019
In 1903, a huge hawk moth,
called the Morgan's sphinx
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00:12:09,054 --> 00:12:10,654
was discovered in Madagascar.
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Attracted by the Comet Orchid's scent,
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the moth slurps its pollen
with its foot-long tongue,
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exactly as Darwin expected it would.
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00:12:25,736 --> 00:12:29,005
It's even more amazing that the
Morgan's sphinx was discovered
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when you consider that more than 90%
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of Madagascar's rain forest
had been destroyed.
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In the years since Darwin's
famous prediction,
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00:12:37,681 --> 00:12:40,850
this moth species could have
easily become extinct
226
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with all the others...
227
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every one of them a unique
phrase of life's poetry,
228
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written in the atoms by eons of evolution.
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00:12:56,566 --> 00:12:58,734
Ah, the fragrance of lilacs.
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It's one of those scents
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that triggers a whole
constellation of associations,
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00:13:03,606 --> 00:13:06,708
all those junes of long ago.
233
00:13:06,743 --> 00:13:08,510
But how does that happen?
234
00:13:08,544 --> 00:13:11,913
How does a smell prompt a movie
to start running in your head?
235
00:13:11,948 --> 00:13:13,914
It's not something we can see.
236
00:13:13,949 --> 00:13:16,217
Could it be a wave of energy, like light?
237
00:13:16,251 --> 00:13:19,687
Or is it some kind of microscopic particle?
238
00:13:19,721 --> 00:13:21,389
It's actually a molecule.
239
00:13:21,423 --> 00:13:25,192
Every odor we can sense, whether
it comes from burnt toast,
240
00:13:25,227 --> 00:13:28,696
gasoline, or a field of lilacs,
241
00:13:28,730 --> 00:13:30,931
is a cloud of molecules.
242
00:13:30,966 --> 00:13:34,769
These molecules have particular shapes.
243
00:13:34,771 --> 00:13:36,737
When I inhale them,
244
00:13:36,739 --> 00:13:40,740
they stimulate a particular set
of receptor cells in my nose.
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An electrical signal
then travels to my brain,
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00:13:44,980 --> 00:13:47,647
which identifies the scent as lilac.
247
00:13:50,951 --> 00:13:53,086
Other scents are carried by
different molecules
248
00:13:53,088 --> 00:13:55,755
with different shapes.
249
00:13:55,757 --> 00:13:59,059
But when I smell a flower or
the smoke from a campfire
250
00:13:59,061 --> 00:14:00,794
or the grease from a motor gear,
251
00:14:00,796 --> 00:14:03,897
I'm often flooded with memories.
252
00:14:03,899 --> 00:14:08,367
Why is it that a simple thing
such as the scent of a flower
253
00:14:08,369 --> 00:14:11,236
can trigger powerful memories?
254
00:14:14,274 --> 00:14:17,776
It has to do with the way
our brains have evolved.
255
00:14:17,778 --> 00:14:20,145
Our sense of smell kicks in
256
00:14:20,147 --> 00:14:22,748
when the olfactory nerve
in our brain is stimulated.
257
00:14:24,517 --> 00:14:27,886
That nerve is located
very close to the amygdala,
258
00:14:27,888 --> 00:14:32,824
a structure that is integral
to our experience of emotion.
259
00:14:32,826 --> 00:14:36,094
It's also very close to the Hippocampus,
260
00:14:36,096 --> 00:14:37,862
which helps us form memories.
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00:14:40,699 --> 00:14:44,035
The network of neurons
that carry the scent signal
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from my nose to my brain
has been fine-tuned
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00:14:46,873 --> 00:14:49,941
over hundreds of millions
of years of evolution.
264
00:14:52,044 --> 00:14:54,345
It's a survival mechanism that can alert us
265
00:14:54,347 --> 00:14:57,214
to danger or guide us to safety.
266
00:14:59,784 --> 00:15:01,818
If you you can detect the predator
267
00:15:01,820 --> 00:15:04,855
before he's near enough to strike,
268
00:15:04,857 --> 00:15:07,190
or the fire before it traps you
in the forest,
269
00:15:07,192 --> 00:15:09,359
you have a much better chance to survive
270
00:15:09,361 --> 00:15:12,195
and pass on your genes
to the next generation.
271
00:15:17,969 --> 00:15:20,537
That lovely scent
from this field of flowers
272
00:15:20,539 --> 00:15:23,572
sets off a unique combination
of nerve signals.
273
00:15:23,574 --> 00:15:27,176
Only that exact combination
can crack the safe
274
00:15:27,178 --> 00:15:30,913
where the memory of lilacs
is stored inside my brain.
275
00:15:35,652 --> 00:15:37,186
Wonder who they're for.
276
00:15:38,655 --> 00:15:40,723
Maybe we'll find out later.
277
00:15:40,725 --> 00:15:44,660
But first, there's another
hidden cosmos waiting for us.
278
00:16:07,103 --> 00:16:09,499
The plants are softly breathing,
279
00:16:09,534 --> 00:16:12,402
inhaling molecules of carbon dioxide
280
00:16:12,437 --> 00:16:15,138
and exhaling molecules of oxygen.
281
00:16:15,173 --> 00:16:16,639
And I'm doing the opposite.
282
00:16:16,673 --> 00:16:20,009
Unlike snowflakes and fingerprints,
283
00:16:20,043 --> 00:16:21,811
atoms or molecules of the same kind
284
00:16:21,845 --> 00:16:24,947
are utterly identical to one another.
285
00:16:24,982 --> 00:16:26,649
With every breath we take,
286
00:16:26,683 --> 00:16:29,852
we inhale as many molecules
as there are stars
287
00:16:29,887 --> 00:16:32,421
in all the galaxies
in the visible universe.
288
00:16:32,456 --> 00:16:35,491
And every breath we exhale
is circulated through the air,
289
00:16:35,525 --> 00:16:38,027
and mixed gradually across the continents,
290
00:16:38,061 --> 00:16:41,997
it becomes available for others to breathe.
291
00:16:42,031 --> 00:16:43,365
Breathe with me.
292
00:16:54,177 --> 00:16:57,679
We all just inhaled about
100 million molecules
293
00:16:57,713 --> 00:16:59,881
that once passed through
the lungs of everyone
294
00:16:59,916 --> 00:17:01,950
who ever lived before us.
295
00:17:01,984 --> 00:17:05,153
Think of it... This kind
of atomic reincarnation
296
00:17:05,188 --> 00:17:07,454
is another link to our distant ancestors,
297
00:17:07,489 --> 00:17:10,991
including those who first
launched us on our explorations
298
00:17:11,026 --> 00:17:13,160
of the unseen universes.
299
00:17:13,195 --> 00:17:16,630
These universes are as real as you or me,
300
00:17:16,665 --> 00:17:18,866
and they surround us.
301
00:17:23,371 --> 00:17:25,739
There was a moment when we awakened
302
00:17:25,774 --> 00:17:28,375
to a new way of thinking and seeing.
303
00:17:28,410 --> 00:17:31,846
It happened about 2,500 years ago
304
00:17:31,880 --> 00:17:33,680
on the Greek islands that lie
305
00:17:33,714 --> 00:17:36,983
between the empires of the east and west.
306
00:17:37,017 --> 00:17:41,087
There, merchants, tourists
and sailors freely mingled,
307
00:17:41,121 --> 00:17:44,224
exchanging tales of great kings and gods.
308
00:17:44,258 --> 00:17:48,728
In Ionian cities and towns like
Miletus, in what is now Turkey,
309
00:17:48,762 --> 00:17:50,930
the most fundamental elements
310
00:17:50,965 --> 00:17:53,867
of the way we live now first appeared.
311
00:17:57,304 --> 00:18:01,573
Here, for the first time,
reenactments of aspects of life
312
00:18:01,608 --> 00:18:04,543
created and executed by professionals
313
00:18:04,577 --> 00:18:07,379
with the expectation of
touching something deep
314
00:18:07,413 --> 00:18:09,181
within the hearts of the audience,
315
00:18:09,215 --> 00:18:12,084
or just making them laugh...
316
00:18:12,118 --> 00:18:16,588
The first plays, dramas and
comedies, were performed.
317
00:18:19,659 --> 00:18:21,593
Government by the people.
318
00:18:21,628 --> 00:18:25,863
The first inklings, imperfect
then as now, of a democracy,
319
00:18:25,898 --> 00:18:28,266
and the notion that the ordinary citizen
320
00:18:28,300 --> 00:18:30,201
might possess certain rights,
321
00:18:30,235 --> 00:18:33,804
come to us from this time and place.
322
00:18:34,707 --> 00:18:38,042
But in my view, the most
revolutionary innovation of all
323
00:18:38,076 --> 00:18:41,879
to come to us from this
ancient world was the idea
324
00:18:41,914 --> 00:18:45,750
that natural events were
neither punishment nor reward
325
00:18:45,784 --> 00:18:47,919
from capricious gods.
326
00:18:47,953 --> 00:18:51,121
The workings of nature could be explained
327
00:18:51,155 --> 00:18:54,291
without invoking the supernatural.
328
00:18:54,325 --> 00:18:56,593
The first person to express this thought
329
00:18:56,627 --> 00:18:58,829
was a man named Thales.
330
00:18:58,863 --> 00:19:00,831
When the thunder clapped
or the earth quaked,
331
00:19:00,865 --> 00:19:03,834
it was not because something
you did had somehow displeased
332
00:19:03,868 --> 00:19:06,069
the very demanding gods.
333
00:19:06,103 --> 00:19:08,905
No, it was the result of natural processes
334
00:19:08,940 --> 00:19:11,441
that we were capable of understanding.
335
00:19:11,475 --> 00:19:15,177
Though none of the books he is
said to have written survive,
336
00:19:15,212 --> 00:19:19,248
Thales kindled a flame
that still burns to this day:
337
00:19:19,282 --> 00:19:21,317
The very idea of cosmos out of chaos,
338
00:19:21,351 --> 00:19:25,120
a universe governed
by the order of natural laws
339
00:19:25,155 --> 00:19:27,122
that we can actually figure out.
340
00:19:27,757 --> 00:19:32,262
This is the epic adventure that
began in the mind of Thales.
341
00:19:33,497 --> 00:19:36,832
Only a century following Thales' death,
342
00:19:36,867 --> 00:19:38,434
another genius came along.
343
00:19:38,468 --> 00:19:40,769
And he, more than any other,
344
00:19:40,804 --> 00:19:43,004
was the first to discover the existence
345
00:19:43,038 --> 00:19:46,040
of the hidden universes that surround us.
346
00:19:46,075 --> 00:19:50,145
Democritus of Abdera was a true scientist,
347
00:19:50,179 --> 00:19:53,548
a man with a passionate desire
to know the cosmos
348
00:19:53,582 --> 00:19:55,350
and to have fun.
349
00:19:55,384 --> 00:19:58,686
This is the man who once said,
"a life without parties
350
00:19:58,721 --> 00:20:02,123
would be like an endless road
without an end."
351
00:20:02,158 --> 00:20:03,892
You mean, that's it?
352
00:20:03,926 --> 00:20:05,527
That's all there is?
353
00:20:05,561 --> 00:20:08,128
Just a bunch of atoms in a void?
354
00:20:08,163 --> 00:20:09,129
Yep.
355
00:20:10,832 --> 00:20:12,166
Well, think about it.
356
00:20:12,200 --> 00:20:13,967
The world has to be made
357
00:20:14,002 --> 00:20:17,304
of countless indivisible
particles in a void.
358
00:20:17,338 --> 00:20:22,109
Otherwise, nothing could move
or grow, be divided or changed.
359
00:20:23,411 --> 00:20:24,645
Without atoms
360
00:20:24,679 --> 00:20:30,362
and empty space for them to move in,
361
00:20:30,397 --> 00:20:32,797
so don't be sad, my friends.
362
00:20:32,832 --> 00:20:35,300
Just think of the infinite possibilities
363
00:20:35,334 --> 00:20:39,103
that arise from different
arrangements of those atoms.
364
00:20:43,042 --> 00:20:44,576
Here's to the atoms
365
00:20:44,610 --> 00:20:48,646
in this cup and in this wine...
366
00:20:48,681 --> 00:20:51,149
And to the laughter they make possible.
367
00:20:53,185 --> 00:20:56,221
Dispersed through
the Clay of the cup
368
00:20:56,255 --> 00:20:58,388
are microscopic mineral grains,
369
00:20:58,423 --> 00:21:01,058
different kinds of crystals,
370
00:21:01,092 --> 00:21:04,661
each with its own distinctive
atomic architecture.
371
00:21:04,696 --> 00:21:07,164
Mineral structures are exquisite,
372
00:21:07,198 --> 00:21:10,167
but they have a limited repertoire.
373
00:21:10,201 --> 00:21:13,437
A grain of quartz is a lattice
of the same three atoms
374
00:21:13,471 --> 00:21:17,307
repeated, without variation,
over and over again.
375
00:21:19,210 --> 00:21:22,880
Even a relatively complex
mineral lattice like topaz,
376
00:21:22,914 --> 00:21:25,348
composed of ten or so atoms,
377
00:21:25,382 --> 00:21:28,017
can only repeat the identical
atomic structure
378
00:21:28,051 --> 00:21:30,052
again and again.
379
00:21:34,317 --> 00:21:36,351
Toenon,
380
00:21:36,385 --> 00:21:39,754
to free it from the lattice
prison of endless repetition,
381
00:21:39,789 --> 00:21:42,224
you need an atom that can bond
in all directions
382
00:21:42,258 --> 00:21:43,859
with other atoms like itself
383
00:21:43,893 --> 00:21:46,795
as well as with atoms of different kinds.
384
00:21:54,236 --> 00:21:56,737
Behold the carbon atom...
385
00:21:56,771 --> 00:21:59,940
the essential element for life on earth.
386
00:21:59,975 --> 00:22:02,810
Why?
387
00:22:02,844 --> 00:22:05,246
Carbon is special because it can bond with
388
00:22:05,280 --> 00:22:07,548
up to four other atoms at a time.
389
00:22:07,582 --> 00:22:10,317
It can connect with many
different kinds of atoms,
390
00:22:10,352 --> 00:22:13,320
as well as other carbon atoms.
391
00:22:13,355 --> 00:22:14,988
It can curl into rings
392
00:22:15,022 --> 00:22:17,223
and string together into chains,
393
00:22:17,258 --> 00:22:21,661
building molecules far more
complex than any crystal.
394
00:22:24,865 --> 00:22:27,767
No other atom has the same flexibility.
395
00:22:27,801 --> 00:22:30,236
Even atoms that have similar
chemical properties,
396
00:22:30,271 --> 00:22:31,838
like silicon,
397
00:22:31,872 --> 00:22:33,973
can't form the amazing variety of molecules
398
00:22:34,008 --> 00:22:36,009
built on carbon.
399
00:22:36,043 --> 00:22:38,578
The carbon-based molecules
we call proteins,
400
00:22:38,612 --> 00:22:40,779
the molecules of life,
401
00:22:40,814 --> 00:22:43,982
contain literally hundreds
of thousands of atoms.
402
00:22:44,017 --> 00:22:47,953
Carbon atoms are the backbone
of the molecules
403
00:22:47,987 --> 00:22:50,189
that make every living thing on earth,
404
00:22:50,223 --> 00:22:52,691
including us.
405
00:22:52,725 --> 00:22:55,961
That's the difference between
rocks and living things.
406
00:22:57,630 --> 00:23:00,032
Life can make enormous molecules
407
00:23:00,066 --> 00:23:02,534
of stunning size and complexity,
408
00:23:02,569 --> 00:23:04,670
freeing matter to improvise,
409
00:23:04,704 --> 00:23:06,704
evolve,
410
00:23:06,738 --> 00:23:08,739
and even love.
411
00:23:41,203 --> 00:23:43,238
Take it easy, dad.
412
00:23:43,272 --> 00:23:45,674
He never actually touched her.
413
00:23:45,708 --> 00:23:47,809
In everyday life on our world,
414
00:23:47,843 --> 00:23:49,444
on the scale of atoms,
415
00:23:49,478 --> 00:23:53,348
material objects never really touch.
416
00:23:53,382 --> 00:23:56,785
Each atom has a tiny nucleus at its center,
417
00:23:56,819 --> 00:24:00,187
surrounded by an electron cloud
of lines of force.
418
00:24:00,221 --> 00:24:02,690
As the atoms approach each other,
419
00:24:02,724 --> 00:24:04,658
the boy's electron clouds
420
00:24:04,693 --> 00:24:06,260
push away the girl's.
421
00:24:06,294 --> 00:24:10,431
More than 99.9% of the matter of any atom
422
00:24:10,465 --> 00:24:12,633
is concentrated in its nucleus.
423
00:24:12,667 --> 00:24:16,106
The nucleus is surrounded
by an electron cloud
424
00:24:16,140 --> 00:24:18,509
which produces an invisible field of force,
425
00:24:18,543 --> 00:24:20,811
and acts like a shock absorber.
426
00:24:20,845 --> 00:24:23,480
The configuration of the electron cloud
427
00:24:23,514 --> 00:24:25,481
determines the nature of an element.
428
00:24:25,516 --> 00:24:28,150
In the ordinary course
of things here on earth,
429
00:24:28,185 --> 00:24:30,052
the nuclei never touch.
430
00:24:30,087 --> 00:24:32,154
We have a sensation of touching,
431
00:24:32,189 --> 00:24:34,790
but that's really just
our invisible force fields
432
00:24:34,825 --> 00:24:37,760
overlapping and repelling each other.
433
00:24:53,543 --> 00:24:55,977
The nucleus is very small
434
00:24:56,012 --> 00:24:57,646
compared to the rest of the atom.
435
00:24:57,680 --> 00:25:01,683
If an atom were the size of this cathedral,
436
00:25:01,717 --> 00:25:05,954
its nucleus would be the size
of that mote of dust.
437
00:25:08,724 --> 00:25:12,928
An atom is mostly empty space.
438
00:25:12,962 --> 00:25:15,664
To understand the nature of matter,
439
00:25:15,698 --> 00:25:17,665
we have to go deeper still,
440
00:25:17,699 --> 00:25:20,701
to a place 100,000 times smaller
than the atom:
441
00:25:20,735 --> 00:25:22,736
Its nucleus.
442
00:25:25,907 --> 00:25:27,675
The simplest and most plentiful atom
443
00:25:27,709 --> 00:25:30,344
in the cosmos is hydrogen.
444
00:25:30,378 --> 00:25:32,580
Its nucleus is a single proton,
445
00:25:32,614 --> 00:25:35,616
which makes hydrogen element number one.
446
00:25:35,650 --> 00:25:37,451
The clouds that surround it
447
00:25:37,485 --> 00:25:39,854
are the realms where
the atom's lone electron
448
00:25:39,888 --> 00:25:42,422
is permitted to roam.
449
00:25:42,456 --> 00:25:45,692
What happens when you have
a nucleus with two protons?
450
00:25:45,726 --> 00:25:47,360
Protons repel each other.
451
00:25:47,394 --> 00:25:49,729
In order to hold them together
in a nucleus,
452
00:25:49,763 --> 00:25:52,932
you need other particles called neutrons.
453
00:25:52,967 --> 00:25:55,535
Their job is to keep the protons
454
00:25:55,569 --> 00:25:56,970
from getting out of line.
455
00:25:57,004 --> 00:25:59,105
They overwhelm the protons
456
00:25:59,139 --> 00:26:01,975
with their strong attractive nuclear force.
457
00:26:02,009 --> 00:26:05,245
A nucleus with two protons
is element number two,
458
00:26:05,279 --> 00:26:07,913
otherwise known as helium.
459
00:26:07,947 --> 00:26:10,949
A nucleus with six protons
is element number six,
460
00:26:10,984 --> 00:26:12,918
which is carbon,
461
00:26:12,952 --> 00:26:16,054
the fundamental building block of life.
462
00:26:16,089 --> 00:26:19,224
The nucleus of a gold atom has 79 protons.
463
00:26:19,259 --> 00:26:21,260
They attract 79 electrons
464
00:26:21,294 --> 00:26:23,095
in clouds around it.
465
00:26:23,129 --> 00:26:25,397
The way light interacts
with those electrons
466
00:26:25,431 --> 00:26:27,997
is what makes gold glitter.
467
00:26:28,031 --> 00:26:30,966
Every additional proton in the nucleus
468
00:26:31,001 --> 00:26:34,269
requires enough neutrons
to bind them together...
469
00:26:34,303 --> 00:26:35,937
Up to a point.
470
00:26:35,971 --> 00:26:38,172
There's an upper limit
to the number of neutrons
471
00:26:38,174 --> 00:26:39,941
you can stuff into a nucleus
472
00:26:39,943 --> 00:26:41,709
before it becomes unstable.
473
00:26:41,711 --> 00:26:43,878
I know a place
474
00:26:43,880 --> 00:26:45,947
where the nuclei of different atoms
475
00:26:45,949 --> 00:26:47,949
actually do touch each other.
476
00:27:08,002 --> 00:27:10,504
The sun looks like a solid object,
477
00:27:10,506 --> 00:27:12,706
but it's not.
478
00:27:12,708 --> 00:27:15,642
It's so hot that all its atoms
479
00:27:15,644 --> 00:27:17,544
are always in their gaseous state.
480
00:27:17,546 --> 00:27:18,979
The bonds that join atoms
481
00:27:18,981 --> 00:27:20,747
to make solids and liquids on earth
482
00:27:20,749 --> 00:27:22,649
are not strong enough to withstand
483
00:27:22,651 --> 00:27:25,618
the heat of the broiling sun.
484
00:27:25,620 --> 00:27:28,487
Those arcing streams of incandescent gas
485
00:27:28,489 --> 00:27:30,690
that dwarf the earth
486
00:27:30,692 --> 00:27:32,825
are guided by magnetic lines of force
487
00:27:32,827 --> 00:27:35,895
that emanate from below
the surface of the sun.
488
00:27:35,897 --> 00:27:38,431
Why is the sun so hot?
489
00:27:38,433 --> 00:27:40,733
Because its own stupendous gravity
490
00:27:40,735 --> 00:27:43,169
is squeezing its atoms together.
491
00:27:45,539 --> 00:27:48,174
The energy of gravity is being transformed
492
00:27:48,176 --> 00:27:50,308
into the energy of moving atoms.
493
00:27:50,310 --> 00:27:53,011
That's what heat is.
494
00:27:53,013 --> 00:27:54,880
The deeper we go into the sun,
495
00:27:54,882 --> 00:27:56,681
the greater the squeezing
496
00:27:56,683 --> 00:27:58,950
and the higher the temperature.
497
00:27:58,952 --> 00:28:00,519
In the heart of the sun,
498
00:28:00,521 --> 00:28:02,354
the atoms are moving so fast
499
00:28:02,356 --> 00:28:04,723
that when they collide, they fuse.
500
00:28:04,725 --> 00:28:08,360
Their nuclei touch.
501
00:28:08,362 --> 00:28:11,796
The sun is a nuclear fusion reactor,
502
00:28:11,798 --> 00:28:14,065
held together by its own gravity.
503
00:28:14,067 --> 00:28:17,401
It's balanced between
the inward pull of gravity
504
00:28:17,403 --> 00:28:20,037
and the outward push of its hot gases.
505
00:28:23,975 --> 00:28:27,278
That balance has lasted billions of years,
506
00:28:27,312 --> 00:28:29,246
providing stability that made possible
507
00:28:29,281 --> 00:28:30,781
the evolution of life on earth.
508
00:28:30,815 --> 00:28:33,217
In the sun's core,
509
00:28:33,251 --> 00:28:35,119
the fusion of hydrogen into helium
510
00:28:35,153 --> 00:28:38,289
releases nuclear energy
in the form of photons.
511
00:28:38,323 --> 00:28:39,957
These particles of light
512
00:28:39,991 --> 00:28:41,891
slowly work their way to the surface,
513
00:28:41,926 --> 00:28:43,626
where they're seen as sunlight.
514
00:28:43,661 --> 00:28:47,564
Helium is the ash
of the sun's nuclear furnace.
515
00:28:49,567 --> 00:28:51,401
The sun is a medium-sized star.
516
00:28:51,435 --> 00:28:55,038
Its core is only a lukewarm
ten million degrees...
517
00:28:55,072 --> 00:28:56,372
hot enough to fuse hydrogen,
518
00:28:56,407 --> 00:28:58,374
but too cold to fuse helium.
519
00:28:58,409 --> 00:29:00,777
There are many stars in the galaxy
520
00:29:00,811 --> 00:29:02,378
that get much hotter,
521
00:29:02,413 --> 00:29:03,913
because they're more massive
522
00:29:03,948 --> 00:29:05,481
and have more gravity.
523
00:29:05,516 --> 00:29:08,650
Such stars fuse helium
into heavier elements,
524
00:29:08,685 --> 00:29:10,619
like carbon and oxygen.
525
00:29:10,653 --> 00:29:12,554
In their old age,
526
00:29:12,589 --> 00:29:15,257
they gently diffuse
these elements into space.
527
00:29:17,660 --> 00:29:19,828
Other stars, more massive yet,
528
00:29:19,863 --> 00:29:22,130
live fast and die young
529
00:29:22,165 --> 00:29:24,132
in cataclysmic supernova explosions.
530
00:29:24,167 --> 00:29:27,336
In our galaxy, such stars go supernova
531
00:29:27,370 --> 00:29:28,770
about once a century.
532
00:29:31,207 --> 00:29:33,841
These explosions are far hotter
than the core of the sun...
533
00:29:33,876 --> 00:29:36,777
hot enough to transform elements like iron
534
00:29:36,812 --> 00:29:39,146
into all the heavier ones
535
00:29:39,181 --> 00:29:42,350
and spew them into space.
536
00:29:42,384 --> 00:29:44,252
The large magellanic cloud
537
00:29:44,286 --> 00:29:46,454
is a neighboring galaxy of our milky way.
538
00:29:46,488 --> 00:29:49,123
It's visible in the skies
of the Southern hemisphere.
539
00:29:50,225 --> 00:29:51,792
When a supernova explodes,
540
00:29:51,827 --> 00:29:53,361
its brightness rivals
541
00:29:53,395 --> 00:29:56,731
that of its entire galaxy.
542
00:30:06,474 --> 00:30:09,609
But all that light
is only about one percent
543
00:30:09,644 --> 00:30:12,279
of the energy liberated in the explosion.
544
00:30:12,313 --> 00:30:15,382
The rest of the energy is
carried off by the most common
545
00:30:15,416 --> 00:30:17,717
and the most mysterious
particles in the cosmos.
546
00:30:17,752 --> 00:30:21,121
There are trillions of them
passing through you right now,
547
00:30:21,155 --> 00:30:23,657
and yet tracking down even one of them
548
00:30:23,691 --> 00:30:27,326
will take us to one of
the strangest places on earth.
549
00:30:36,996 --> 00:30:39,064
Stalking the wild neutrino
550
00:30:39,098 --> 00:30:40,899
is the rarest of sport.
551
00:30:40,933 --> 00:30:43,468
The lengths one must go to track them down
552
00:30:43,503 --> 00:30:45,237
is nothing short of astonishing.
553
00:30:45,271 --> 00:30:48,907
Welcome to Super Kamiokande,
554
00:30:48,941 --> 00:30:52,743
the subterranean Japanese
neutrino detection chamber.
555
00:30:52,777 --> 00:30:55,913
We're more than a half mile
beneath earth's surface.
556
00:30:55,947 --> 00:30:58,182
You might ask,
"well, who in their right mind
557
00:30:58,216 --> 00:31:01,418
would bury an astronomical
observatory so far underground?"
558
00:31:01,453 --> 00:31:04,989
Those who hunt the most elusive
prey in the cosmos:
559
00:31:05,023 --> 00:31:06,991
The neutrino.
560
00:31:07,025 --> 00:31:08,993
This enormous array of light detectors
561
00:31:09,027 --> 00:31:12,062
surrounding 50,000 tons of distilled water
562
00:31:12,097 --> 00:31:15,566
is a trap designed to catch neutrinos only.
563
00:31:15,600 --> 00:31:18,001
Other particles, such as cosmic rays...
564
00:31:18,035 --> 00:31:21,004
mostly protons and electrons
that rain down from space...
565
00:31:21,038 --> 00:31:23,606
cannot get through all that rock above us.
566
00:31:23,641 --> 00:31:27,010
But matter poses no obstacle to a neutrino.
567
00:31:27,044 --> 00:31:31,047
A neutrino could pass through
100 light-years of steel
568
00:31:31,081 --> 00:31:33,516
without even slowing down.
569
00:31:33,551 --> 00:31:36,252
Neutrinos hardly interact
with matter at all.
570
00:31:36,287 --> 00:31:37,954
That's why you need so much of it
571
00:31:37,988 --> 00:31:39,556
to catch even one of them.
572
00:31:39,590 --> 00:31:41,624
On those rare occasions when a neutrino
573
00:31:41,659 --> 00:31:44,393
actually does collide with
a particle of ordinary matter,
574
00:31:44,427 --> 00:31:48,597
it produces a ghostly,
ring-shaped flash of light.
575
00:31:48,631 --> 00:31:51,300
We're lying in wait
576
00:31:51,334 --> 00:31:54,903
for a particle that weighs next to nothing.
577
00:31:54,938 --> 00:31:56,905
Even the miniscule electron
578
00:31:56,940 --> 00:31:59,908
has more than a million times its mass...
579
00:31:59,943 --> 00:32:01,610
There!
580
00:32:01,644 --> 00:32:03,812
When the supernova in
the large magellanic cloud
581
00:32:03,847 --> 00:32:06,114
blew its top in 1987,
582
00:32:06,149 --> 00:32:09,050
this is what it would have
looked like in here.
583
00:32:09,084 --> 00:32:11,486
Now remember, the large magellanic cloud
584
00:32:11,520 --> 00:32:12,820
is in our Southern hemisphere,
585
00:32:12,855 --> 00:32:14,422
so the neutrinos didn't come through
586
00:32:14,456 --> 00:32:16,057
that half-mile of rock above us,
587
00:32:16,091 --> 00:32:18,659
they had to pass through
the thousands of miles
588
00:32:18,694 --> 00:32:21,496
of rock and iron below us
to reach this detector.
589
00:32:21,530 --> 00:32:24,165
But the coolest thing
was that those neutrinos
590
00:32:24,199 --> 00:32:26,801
hit earth three hours before
591
00:32:26,835 --> 00:32:28,836
the light from the supernova did.
592
00:32:28,871 --> 00:32:31,072
If nothing can travel faster than light,
593
00:32:31,106 --> 00:32:33,508
how could that possibly be?
594
00:32:39,113 --> 00:32:41,982
This is a dead star walking.
595
00:32:42,016 --> 00:32:45,485
It may look normal, but deep within it
596
00:32:45,520 --> 00:32:47,954
something cataclysmic is happening.
597
00:32:47,989 --> 00:32:50,323
This blue super giant star
598
00:32:50,358 --> 00:32:54,795
has already begun to explode inside.
599
00:32:58,399 --> 00:33:01,967
Like rats deserting
a sinking ship, the neutrinos
600
00:33:02,002 --> 00:33:04,470
produced in the heart of the exploding star
601
00:33:04,504 --> 00:33:07,039
race outward at near the speed of light,
602
00:33:07,073 --> 00:33:09,442
through overlying mass
603
00:33:09,476 --> 00:33:11,043
in only a few seconds.
604
00:33:11,077 --> 00:33:13,279
But the shock wave of the exploding gas
605
00:33:13,313 --> 00:33:16,315
plods along from the center of the star
606
00:33:16,349 --> 00:33:18,951
at 1/10,000 the speed of light
607
00:33:18,985 --> 00:33:21,187
until it finally reaches
608
00:33:21,221 --> 00:33:22,655
the star's surface,
609
00:33:22,689 --> 00:33:26,424
turning it into supernova 1987a.
610
00:33:32,531 --> 00:33:34,199
It took hours for the explosion
611
00:33:34,233 --> 00:33:36,801
to reach the surface of the star
and blow it wide open,
612
00:33:36,836 --> 00:33:38,636
exposing the super hot core.
613
00:33:38,671 --> 00:33:41,706
The neutrinos had
an insurmountable head start.
614
00:33:41,740 --> 00:33:44,542
That's why the flash of light
arrived on earth
615
00:33:44,577 --> 00:33:47,545
so much later than the shower of neutrinos.
616
00:33:47,580 --> 00:33:51,015
Before anyone had ever snared
the wild neutrino,
617
00:33:51,050 --> 00:33:54,918
it existed in the mind
of a theoretical physicist.
618
00:33:54,953 --> 00:33:57,988
Just as Charles Darwin knew
619
00:33:58,022 --> 00:34:00,591
there must be
an extremely long-nosed creature
620
00:34:00,625 --> 00:34:02,593
flying around somewhere in Madagascar,
621
00:34:02,627 --> 00:34:06,463
a 20th-century physicist
named Wolfgang Pauli...
622
00:34:09,467 --> 00:34:11,401
was desperately seeking a particle
623
00:34:11,436 --> 00:34:13,704
to rescue one of the pillars of
modern physics,
624
00:34:13,738 --> 00:34:17,074
the law of the conservation of energy.
625
00:34:25,916 --> 00:34:27,950
So why didn't I flinch?
626
00:34:27,985 --> 00:34:30,253
Because the laws of science
differ fundamentally
627
00:34:30,287 --> 00:34:32,088
from those of other human endeavors.
628
00:34:32,122 --> 00:34:35,625
In order for an idea
to become a scientific law,
629
00:34:35,659 --> 00:34:37,460
it has to unbreakable.
630
00:34:37,494 --> 00:34:40,229
That's why I was willing to bet this face
631
00:34:40,264 --> 00:34:43,131
on the laws of conservation of energy.
632
00:34:43,166 --> 00:34:45,567
Now, if you try this at home,
633
00:34:45,601 --> 00:34:48,570
take care not to give
the cannonball a push.
634
00:34:48,604 --> 00:34:50,205
That's adding energy,
635
00:34:50,239 --> 00:34:52,774
and the ball will surely
come back and do some damage.
636
00:34:52,809 --> 00:34:55,811
You just have to let it go, like this.
637
00:34:57,013 --> 00:34:58,313
By lifting the ball,
638
00:34:58,347 --> 00:35:00,048
you give it gravitational energy,
639
00:35:00,082 --> 00:35:03,051
which is the potential
to fall and accelerate.
640
00:35:03,085 --> 00:35:04,619
The cannonball is going fastest
641
00:35:04,654 --> 00:35:06,288
when it's at the bottom of its arc,
642
00:35:06,322 --> 00:35:07,956
and at that moment,
643
00:35:07,990 --> 00:35:10,157
it's converted all
of its gravitational energy
644
00:35:10,192 --> 00:35:12,226
to the energy of motion.
645
00:35:12,260 --> 00:35:14,929
As it swings, the cannonball
is constantly exchanging
646
00:35:14,963 --> 00:35:17,164
one of these two kinds of energy
for the other,
647
00:35:17,199 --> 00:35:20,401
but the total amount of energy
remains constant.
648
00:35:20,435 --> 00:35:23,771
That's an example of the
law of conservation of energy.
649
00:35:23,805 --> 00:35:26,240
Once the cannonball is released,
650
00:35:26,274 --> 00:35:29,310
it can never gain more energy
than it had to begin with.
651
00:35:29,344 --> 00:35:32,646
It has no way to fly up and break my nose.
652
00:35:32,681 --> 00:35:36,649
The energy accounting books
are always strictly balanced.
653
00:35:36,684 --> 00:35:39,018
There's no such thing as cheating.
654
00:35:39,053 --> 00:35:40,854
So in the 20th century,
655
00:35:40,888 --> 00:35:44,257
when physicists first calculated
the energy of atoms precisely,
656
00:35:44,291 --> 00:35:45,525
they were startled to discover
657
00:35:45,559 --> 00:35:48,061
an apparent violation of this law.
658
00:35:50,164 --> 00:35:52,632
They found that in some radioactive atoms,
659
00:35:52,666 --> 00:35:56,035
the nucleus can spontaneously
eject an electron.
660
00:35:56,070 --> 00:35:59,606
This transforms the atom
into a different element.
661
00:35:59,640 --> 00:36:02,174
The physicists were mystified.
662
00:36:02,208 --> 00:36:04,276
The energy of the escaped electron
663
00:36:04,310 --> 00:36:06,278
plus that of the new element
664
00:36:06,312 --> 00:36:09,615
adds up to less than the energy
in the original nucleus.
665
00:36:09,649 --> 00:36:11,517
But the law says,
666
00:36:11,551 --> 00:36:14,453
"thou shall not destroy or create energy."
667
00:36:14,487 --> 00:36:17,322
So where did the missing energy go?
668
00:36:17,357 --> 00:36:19,491
In 1930...
669
00:36:19,526 --> 00:36:22,061
Wolfgang Pauli predicted
670
00:36:22,095 --> 00:36:24,196
there must be an undiscovered particle,
671
00:36:24,230 --> 00:36:26,664
one that makes off with the missing energy.
672
00:36:26,698 --> 00:36:29,467
At the time, Pauli lamented
673
00:36:29,501 --> 00:36:32,904
that such a phantom particle
might be so minute,
674
00:36:32,938 --> 00:36:34,839
swift and evasive
675
00:36:34,873 --> 00:36:37,909
as to forever defy detection.
676
00:36:37,943 --> 00:36:41,345
But that was a rare failure
of his imagination
677
00:36:41,380 --> 00:36:43,548
because science is always searching
678
00:36:43,582 --> 00:36:45,416
for a way to go deeper still.
679
00:36:45,451 --> 00:36:47,351
A generation later,
680
00:36:47,386 --> 00:36:49,721
Pauli's neutrinos were actually
detected for the first time
681
00:36:49,755 --> 00:36:52,322
in radiation from a nuclear reactor.
682
00:36:52,356 --> 00:36:56,259
And we've been finding them,
with difficulty, ever since.
683
00:36:57,724 --> 00:36:58,980
There are scientists today
684
00:36:59,015 --> 00:37:02,215
who are trying to find a way
to ride those neutrinos
685
00:37:02,250 --> 00:37:05,752
all the way back to the beginning of time.
686
00:37:07,255 --> 00:37:09,122
We'll go as far as they have gone
687
00:37:09,157 --> 00:37:13,093
to come up against the wall of forever.
688
00:37:22,539 --> 00:37:25,274
The wall of
forever is nothing new.
689
00:37:25,308 --> 00:37:27,242
Our ancestors came up against it
690
00:37:27,277 --> 00:37:30,379
almost as soon as they first
started imagining it.
691
00:37:30,413 --> 00:37:35,184
A million dawns ago,
in the 13th century bc,
692
00:37:35,218 --> 00:37:38,721
the Egyptian this temple at Abu Simbel
693
00:37:38,755 --> 00:37:40,789
to honor the Pharaoh Ramses II,
694
00:37:40,824 --> 00:37:44,026
depicted here in four colossal statues.
695
00:37:44,060 --> 00:37:46,961
Reigning even above even this mighty king
696
00:37:46,996 --> 00:37:49,964
is the falcon-headed Ra-Harakhti,
697
00:37:49,999 --> 00:37:52,233
God of the sun.
698
00:37:56,672 --> 00:37:58,773
The temple was designed
699
00:37:58,807 --> 00:38:00,541
so that the light from the rising sun
700
00:38:00,576 --> 00:38:04,879
could only enter the sanctuary
on two days every year.
701
00:38:04,914 --> 00:38:07,916
As the rays enter the temple,
702
00:38:07,950 --> 00:38:09,884
they burnish the statues of the gods
703
00:38:09,919 --> 00:38:11,551
with their golden light
704
00:38:11,586 --> 00:38:15,556
before penetrating the sanctuary.
705
00:38:15,590 --> 00:38:19,560
Even then, one God remains in shadow.
706
00:38:19,594 --> 00:38:22,062
Ptah, lord of creation,
707
00:38:22,096 --> 00:38:24,298
as if the origin of the universe
708
00:38:24,332 --> 00:38:27,167
must forever be concealed.
709
00:38:30,872 --> 00:38:33,674
Feel the sun on your face.
710
00:38:33,708 --> 00:38:36,275
The energy that warms you
711
00:38:36,310 --> 00:38:39,445
began its journey
some ten million years ago
712
00:38:39,479 --> 00:38:41,581
in the heart of the sun.
713
00:38:41,615 --> 00:38:44,650
Unlike neutrinos,
714
00:38:44,685 --> 00:38:46,485
the photons needed
715
00:38:46,520 --> 00:38:49,488
that long to work their way out
from the core to the surface.
716
00:38:49,523 --> 00:38:51,524
Why?
717
00:38:51,558 --> 00:38:54,460
Because they were colliding
billions of times per second
718
00:38:54,494 --> 00:38:56,762
with the sun's atoms, every collision
719
00:38:56,797 --> 00:38:59,765
sending them off in a random direction.
720
00:38:59,800 --> 00:39:01,766
But once they finally reached the surface,
721
00:39:01,801 --> 00:39:03,201
they were free
722
00:39:03,236 --> 00:39:05,937
to dash nonstop, at the speed of light,
723
00:39:05,972 --> 00:39:08,173
in a mere eight minutes and 20 seconds
724
00:39:08,207 --> 00:39:09,975
from the sun to you.
725
00:39:11,711 --> 00:39:14,846
Ten-million-year-old light on your face.
726
00:39:17,216 --> 00:39:19,484
What was happening
727
00:39:19,519 --> 00:39:22,854
when that light left the heart of the sun?
728
00:39:27,759 --> 00:39:30,794
The cosmic calendar compresses
729
00:39:30,829 --> 00:39:33,631
the entire 13.8 billion year history
730
00:39:33,665 --> 00:39:35,733
of the universe into a single year.
731
00:39:35,767 --> 00:39:39,303
Every month represents
about a billion years.
732
00:39:39,337 --> 00:39:42,206
Every day, about 40 million years.
733
00:39:42,240 --> 00:39:45,476
The universe is so old that,
on the cosmic calendar,
734
00:39:45,510 --> 00:39:49,246
ten million years ago
only takes us back as far as...
735
00:39:49,281 --> 00:39:52,883
6:00 P.M. on the last evening
736
00:39:52,918 --> 00:39:55,752
of the last day of the year.
737
00:39:55,786 --> 00:39:57,353
And what about us?
738
00:39:57,388 --> 00:39:59,222
Humans had yet to evolve.
739
00:39:59,256 --> 00:40:00,990
Ten million years ago,
740
00:40:01,025 --> 00:40:03,426
our ancestors were anthropoid apes,
741
00:40:03,460 --> 00:40:05,361
swinging through the trees of Africa.
742
00:40:05,396 --> 00:40:08,865
To us, ten million years
seems like a long time,
743
00:40:08,899 --> 00:40:11,267
but it's only the length of an afternoon
744
00:40:11,302 --> 00:40:13,770
on the timescale of the cosmos.
745
00:40:17,107 --> 00:40:19,708
The sun began fusing hydrogen
746
00:40:19,742 --> 00:40:22,044
4,500 million years ago...
747
00:40:22,078 --> 00:40:25,781
August 31 on the cosmic calendar.
748
00:40:25,815 --> 00:40:27,850
Our milky way galaxy
749
00:40:27,884 --> 00:40:30,953
is about 10,000 million years old.
750
00:40:30,987 --> 00:40:36,058
The first galaxies formed about
a few billion years earlier.
751
00:40:36,092 --> 00:40:40,028
Something keeps me from going
any further back in time.
752
00:40:40,063 --> 00:40:42,064
What is this?
753
00:40:45,734 --> 00:40:47,602
It's the nature of light and time.
754
00:40:47,636 --> 00:40:50,805
Because light travels at a finite speed,
755
00:40:50,839 --> 00:40:53,107
to look across space
756
00:40:53,142 --> 00:40:55,810
is to look back in time.
757
00:40:58,747 --> 00:41:00,882
So the farther we see,
758
00:41:00,916 --> 00:41:03,718
the older the light.
759
00:41:03,752 --> 00:41:06,554
This is as far back
in the history of the cosmos
760
00:41:06,588 --> 00:41:08,556
as we can see with light.
761
00:41:08,590 --> 00:41:10,991
It's a baby picture of universe,
762
00:41:11,025 --> 00:41:14,094
when it was only 380,000 years old.
763
00:41:14,128 --> 00:41:17,898
That's 15 minutes into January 1
764
00:41:17,932 --> 00:41:19,766
on the cosmic calendar.
765
00:41:19,801 --> 00:41:22,936
If we look as far as we can see
in any direction
766
00:41:22,970 --> 00:41:24,938
using microwave telescopes,
767
00:41:24,972 --> 00:41:26,406
this is what we see,
768
00:41:26,441 --> 00:41:29,743
the glow left over from the Big Bang.
769
00:41:29,777 --> 00:41:31,745
Imagine that all the matter and energy
770
00:41:31,779 --> 00:41:33,647
of the observable universe
771
00:41:33,681 --> 00:41:35,415
was concentrated into something
772
00:41:35,450 --> 00:41:37,950
no larger than this.
773
00:41:37,984 --> 00:41:41,854
That's the size of the universe
774
00:41:41,888 --> 00:41:44,256
when it was a trillionth of a trillionth
775
00:41:44,291 --> 00:41:47,259
of a trillionth of a second old.
776
00:41:47,294 --> 00:41:50,830
All the matter and energy
of the hundred billion galaxies
777
00:41:50,864 --> 00:41:53,933
now splayed out across
the billions of light-years
778
00:41:53,967 --> 00:41:55,935
were once pent up
779
00:41:55,969 --> 00:41:58,304
in something the size of a marble.
780
00:41:58,338 --> 00:42:00,372
Can you imagine how tightly packed
781
00:42:00,407 --> 00:42:02,273
that marble must have been?
782
00:42:02,308 --> 00:42:05,143
Far too dense for any kind
of light to move through it,
783
00:42:05,177 --> 00:42:08,947
but no obstacle for the likes of neutrinos.
784
00:42:08,981 --> 00:42:11,850
The big bang must have produced
stupendous numbers of neutrinos,
785
00:42:11,884 --> 00:42:13,451
which flew unhindered
786
00:42:13,486 --> 00:42:15,553
through that inconceivable crush of matter.
787
00:42:15,588 --> 00:42:18,790
The very thing that makes them
almost impossible to detect
788
00:42:18,824 --> 00:42:22,894
is what allows neutrinos
to sail through the curtain
789
00:42:22,928 --> 00:42:25,563
that conceals the beginning of time.
790
00:42:25,598 --> 00:42:27,164
Where are they now?
791
00:42:27,198 --> 00:42:28,732
They are here, they're there,
792
00:42:28,767 --> 00:42:30,968
everywhere throughout the universe.
793
00:42:31,002 --> 00:42:33,837
Neutrinos from creation are within you.
794
00:42:34,906 --> 00:42:37,141
From a marble...
795
00:42:37,175 --> 00:42:39,176
To the cosmos.
796
00:42:49,921 --> 00:42:53,222
This is the road that Thales
and Democritus put us on
797
00:42:53,257 --> 00:42:56,025
some 2,500 years ago...
798
00:42:56,059 --> 00:42:58,094
a road of endless searching,
799
00:42:58,128 --> 00:43:01,431
a relentless, systematic hunt
for new worlds
800
00:43:01,465 --> 00:43:04,100
and an ever-deepening
understanding of nature.
801
00:43:05,569 --> 00:43:08,438
Who among you will pick up that torch
802
00:43:08,472 --> 00:43:12,075
and take us down that next stretch of road?
60952
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