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NEIL DEGRASSE TYSON:
We live on one level
of existence.
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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,
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 in 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
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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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¶ ¶
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¶ ¶
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¶ ¶
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(wind whistling)
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DEGRASSE TYSON: 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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DEGRASSE TYSON: 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
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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,
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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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that Darwin was proven right.
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In 1903, a huge hawk moth,
called the Morgan's Sphinx
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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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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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this moth species could have
easily become extinct
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with all the others--
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every one of them a unique
phrase of life's poetry,
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written in the atoms
by eons of evolution.
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(inhales)
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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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all those Junes of long ago.
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00:13:02,748 --> 00:13:04,516
But how does that happen?
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How does a smell prompt a movie
to start running in your head?
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It's not something we can see.
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Could it be a wave of energy,
like light?
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Or is it some kind
of microscopic particle?
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It's actually a molecule.
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Every odor we can sense, whether
it comes from burnt toast,
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gasoline,
or a field of lilacs...
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is a cloud of molecules.
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These molecules have
particular shapes.
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When I inhale them,
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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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which identifies the scent
as lilac.
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Other scents are carried by
different molecules
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with different shapes.
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00:13:51,765 --> 00:13:55,066
But when I smell a flower or
the smoke from a campfire
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or the grease
from a motor gear,
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I'm often flooded
with memories.
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Why is it that a simple thing
such as the scent of a flower
259
00:14:04,377 --> 00:14:07,245
can trigger powerful memories?
260
00:14:10,282 --> 00:14:13,785
It has to do with the way
our brains have evolved.
261
00:14:13,787 --> 00:14:16,154
Our sense of smell kicks in
262
00:14:16,156 --> 00:14:18,756
when the olfactory nerve
in our brain is stimulated.
263
00:14:20,526 --> 00:14:23,878
That nerve is located
very close to the amygdala,
264
00:14:23,880 --> 00:14:28,833
a structure that is integral
to our experience of emotion.
265
00:14:28,835 --> 00:14:32,103
It's also very close
to the hippocampus,
266
00:14:32,105 --> 00:14:33,872
which helps us form memories.
267
00:14:36,709 --> 00:14:40,044
The network of neurons
that carry the scent signal
268
00:14:40,046 --> 00:14:42,881
from my nose to my brain
has been fine-tuned
269
00:14:42,883 --> 00:14:45,950
over hundreds of millions
of years of evolution.
270
00:14:48,053 --> 00:14:50,355
It's a survival mechanism
that can alert us
271
00:14:50,357 --> 00:14:53,224
to danger
or guide us to safety.
272
00:14:55,794 --> 00:14:57,829
If you you can detect
the predator
273
00:14:57,831 --> 00:15:00,865
before he's near enough
to strike,
274
00:15:00,867 --> 00:15:03,201
or the fire before it traps you
in the forest,
275
00:15:03,203 --> 00:15:05,370
you have a much better chance
to survive
276
00:15:05,372 --> 00:15:08,206
and pass on your genes
to the next generation.
277
00:15:13,979 --> 00:15:16,547
That lovely scent
from this field of flowers
278
00:15:16,549 --> 00:15:19,584
sets off a unique combination
of nerve signals.
279
00:15:19,586 --> 00:15:23,187
Only that exact combination
can crack the safe
280
00:15:23,189 --> 00:15:26,925
where the memory of lilacs
is stored inside my brain.
281
00:15:31,664 --> 00:15:33,197
Wonder who they're for.
282
00:15:34,667 --> 00:15:36,734
Maybe we'll find out later.
283
00:15:36,736 --> 00:15:40,672
But first, there's another
hidden cosmos waiting for us.
284
00:15:46,095 --> 00:15:48,596
(deGrasse Tyson inhaling)
285
00:15:48,631 --> 00:15:51,065
(exhaling)
286
00:15:51,100 --> 00:15:52,667
(inhaling)
287
00:15:52,701 --> 00:15:54,202
(exhaling)
288
00:15:56,338 --> 00:15:57,972
(inhaling)
289
00:15:58,007 --> 00:16:00,942
(exhaling)
290
00:16:00,976 --> 00:16:03,511
The plants are softly breathing,
291
00:16:03,545 --> 00:16:06,414
inhaling molecules
of carbon dioxide
292
00:16:06,448 --> 00:16:09,150
and exhaling molecules
of oxygen.
293
00:16:09,184 --> 00:16:10,652
And I'm doing the opposite.
294
00:16:10,686 --> 00:16:14,022
Unlike snowflakes
and fingerprints,
295
00:16:14,056 --> 00:16:15,823
atoms or molecules
of the same kind
296
00:16:15,858 --> 00:16:18,960
are utterly identical
to one another.
297
00:16:18,994 --> 00:16:20,662
With every breath we take,
298
00:16:20,696 --> 00:16:23,865
we inhale as many molecules
as there are stars
299
00:16:23,899 --> 00:16:26,434
in all the galaxies
in the visible universe.
300
00:16:26,468 --> 00:16:29,504
And every breath we exhale
is circulated through the air,
301
00:16:29,538 --> 00:16:32,040
and mixed gradually
across the continents,
302
00:16:32,074 --> 00:16:36,010
It becomes available
for others to breathe.
303
00:16:36,045 --> 00:16:37,378
Breathe with me.
304
00:16:37,413 --> 00:16:41,416
(inhales, exhales)
305
00:16:48,190 --> 00:16:51,693
We all just inhaled about
100 million molecules
306
00:16:51,727 --> 00:16:53,895
that once passed through
the lungs of everyone
307
00:16:53,929 --> 00:16:55,963
who ever lived before us.
308
00:16:55,998 --> 00:16:59,167
Think of it-- this kind
of atomic reincarnation
309
00:16:59,201 --> 00:17:01,469
is another link
to our distant ancestors,
310
00:17:01,503 --> 00:17:05,006
including those who first
launched us on our explorations
311
00:17:05,040 --> 00:17:07,175
of the unseen universes.
312
00:17:07,209 --> 00:17:10,645
These universes
are as real as you or me,
313
00:17:10,679 --> 00:17:12,880
and they surround us.
314
00:17:17,386 --> 00:17:19,754
There was a moment
when we awakened
315
00:17:19,788 --> 00:17:22,390
to a new way
of thinking and seeing.
316
00:17:22,424 --> 00:17:25,860
It happened
about 2,500 years ago
317
00:17:25,894 --> 00:17:27,695
on the Greek islands that lie
318
00:17:27,730 --> 00:17:30,998
between the empires
of the East and West.
319
00:17:31,033 --> 00:17:35,103
There, merchants, tourists
and sailors freely mingled,
320
00:17:35,137 --> 00:17:38,239
exchanging tales
of great kings and gods.
321
00:17:38,273 --> 00:17:42,744
In Ionian cities and towns like
Miletus, in what is now Turkey,
322
00:17:42,778 --> 00:17:44,946
the most fundamental elements
323
00:17:44,980 --> 00:17:47,882
of the way we live now
first appeared.
324
00:17:51,353 --> 00:17:55,590
Here, for the first time,
reenactments of aspects of life
325
00:17:55,624 --> 00:17:58,559
created and executed
by professionals
326
00:17:58,594 --> 00:18:01,395
with the expectation of
touching something deep
327
00:18:01,463 --> 00:18:03,197
within the hearts
of the audience,
328
00:18:03,232 --> 00:18:06,100
or just making them laugh...
329
00:18:06,135 --> 00:18:10,605
the first plays, dramas and
comedies, were performed.
330
00:18:10,639 --> 00:18:13,641
Here, also, was born
a radical new idea:
331
00:18:13,659 --> 00:18:15,610
government by the people.
332
00:18:15,644 --> 00:18:19,881
The first inklings, imperfect
then as now, of a democracy,
333
00:18:19,915 --> 00:18:22,283
and the notion
that the ordinary citizen
334
00:18:22,317 --> 00:18:24,218
might possess certain rights,
335
00:18:24,253 --> 00:18:27,822
come to us
from this time and place.
336
00:18:27,856 --> 00:18:29,590
(thunder rumbles)
337
00:18:29,625 --> 00:18:32,059
But in my view, the most
revolutionary innovation
338
00:18:32,094 --> 00:18:35,897
of all to come to us from this
ancient world was the idea
339
00:18:35,931 --> 00:18:39,767
that natural events were
neither punishment nor reward
340
00:18:39,802 --> 00:18:41,936
from capricious gods.
341
00:18:41,970 --> 00:18:45,139
The workings of nature
could be explained
342
00:18:45,174 --> 00:18:48,309
without invoking
the supernatural.
343
00:18:48,343 --> 00:18:50,611
The first person
to express this thought
344
00:18:50,646 --> 00:18:52,847
was a man named Thales.
345
00:18:52,881 --> 00:18:54,849
When the thunder clapped
or the earth quaked,
346
00:18:54,883 --> 00:18:57,852
it was not because something
you did had somehow displeased
347
00:18:57,886 --> 00:19:00,087
the very demanding gods.
348
00:19:00,122 --> 00:19:02,924
No, it was the result
of natural processes
349
00:19:02,958 --> 00:19:05,459
that we were capable
of understanding.
350
00:19:05,494 --> 00:19:09,197
Though none of the books he is
said to have written survive,
351
00:19:09,231 --> 00:19:13,267
Thales kindled a flame
that still burns to this day:
352
00:19:13,302 --> 00:19:15,336
the very idea of cosmos out
of chaos,
353
00:19:15,370 --> 00:19:19,140
a universe governed
by the order of natural laws
354
00:19:19,174 --> 00:19:21,142
that we can
actually figure out.
355
00:19:21,176 --> 00:19:27,481
This is the epic adventure that
began in the mind of Thales.
356
00:19:27,549 --> 00:19:30,852
Only a century following
Thales' death,
357
00:19:30,886 --> 00:19:32,453
another genius came along.
358
00:19:32,487 --> 00:19:34,789
And he, more than any other,
359
00:19:34,823 --> 00:19:37,024
was the first to discover
the existence
360
00:19:37,059 --> 00:19:40,061
of the hidden universes
that surround us.
361
00:19:40,095 --> 00:19:44,165
Democritus of Abdera
was a true scientist,
362
00:19:44,199 --> 00:19:47,568
a man with a passionate desire
to know the cosmos
363
00:19:47,603 --> 00:19:49,370
and to have fun.
364
00:19:49,404 --> 00:19:52,707
This is the man who once said,
"A life without parties
365
00:19:52,741 --> 00:19:56,143
would be like an endless road
without an end."
366
00:19:56,178 --> 00:19:57,912
You mean, that's it?
367
00:19:57,914 --> 00:19:59,480
That's all there is?
368
00:19:59,581 --> 00:20:02,149
Just a bunch of atoms
in a void?
369
00:20:02,184 --> 00:20:03,150
Yep.
370
00:20:03,168 --> 00:20:04,819
(laughs)
371
00:20:04,853 --> 00:20:06,187
Well, think about it.
372
00:20:06,221 --> 00:20:07,972
The world has to be made
373
00:20:08,023 --> 00:20:11,325
of countless indivisible
particles in a void.
374
00:20:11,327 --> 00:20:16,130
Otherwise, nothing could move
or grow, be divided or changed.
375
00:20:17,432 --> 00:20:18,666
Without atoms
376
00:20:18,700 --> 00:20:20,835
and empty space
for them to move in,
377
00:20:20,837 --> 00:20:24,405
the world would be solid,
static and dead.
378
00:20:24,439 --> 00:20:26,841
So don't be sad, my friends.
379
00:20:26,875 --> 00:20:29,343
Just think of
the infinite possibilities
380
00:20:29,378 --> 00:20:33,147
that arise from different
arrangements of those atoms.
381
00:20:37,085 --> 00:20:38,619
Here's to the atoms
382
00:20:38,654 --> 00:20:42,690
in this cup and in this wine...
383
00:20:42,724 --> 00:20:45,192
and to the laughter
they make possible.
384
00:20:45,227 --> 00:20:47,194
(all laugh)
385
00:20:47,229 --> 00:20:50,264
DEGRASSE TYSON:
Dispersed through the clay
of the cup
386
00:20:50,299 --> 00:20:52,433
are microscopic mineral grains,
387
00:20:52,467 --> 00:20:55,135
different kinds of crystals,
388
00:20:55,137 --> 00:20:58,706
each with its own distinctive
atomic architecture.
389
00:20:58,740 --> 00:21:01,208
Mineral structures
are exquisite,
390
00:21:01,243 --> 00:21:04,211
but they have
a limited repertoire.
391
00:21:04,246 --> 00:21:07,481
A grain of quartz is a lattice
of the same three atoms
392
00:21:07,516 --> 00:21:11,352
repeated, without variation,
over and over again.
393
00:21:13,255 --> 00:21:16,924
Even a relatively complex
mineral lattice like topaz,
394
00:21:16,959 --> 00:21:19,393
composed of ten or so atoms,
395
00:21:19,428 --> 00:21:22,063
can only repeat the identical
atomic structure
396
00:21:22,097 --> 00:21:24,098
again and again.
397
00:21:28,370 --> 00:21:30,404
To lift matter
to another dimension,
398
00:21:30,439 --> 00:21:33,808
to free it from the lattice
prison of endless repetition,
399
00:21:33,842 --> 00:21:36,277
you need an atom that can bond
in all directions
400
00:21:36,311 --> 00:21:37,912
with other atoms like itself
401
00:21:37,946 --> 00:21:40,848
as well as with atoms
of different kinds.
402
00:21:48,290 --> 00:21:50,791
Behold the carbon atom--
403
00:21:50,826 --> 00:21:53,978
the essential element
for life on Earth.
404
00:21:54,029 --> 00:21:56,830
Why?
405
00:21:56,882 --> 00:21:59,300
Carbon is special
because it can bond with
406
00:21:59,334 --> 00:22:01,602
up to four other atoms
at a time.
407
00:22:01,636 --> 00:22:04,372
It can connect with many
different kinds of atoms,
408
00:22:04,389 --> 00:22:07,408
as well as other carbon atoms.
409
00:22:07,410 --> 00:22:09,043
It can curl into rings
410
00:22:09,077 --> 00:22:11,278
and string together
into chains,
411
00:22:11,313 --> 00:22:15,716
building molecules far more
complex than any crystal.
412
00:22:18,920 --> 00:22:21,822
No other atom has
the same flexibility.
413
00:22:21,857 --> 00:22:24,324
Even atoms that have similar
chemical properties,
414
00:22:24,326 --> 00:22:25,893
like silicon,
415
00:22:25,927 --> 00:22:28,029
can't form the amazing
variety of molecules
416
00:22:28,063 --> 00:22:30,064
built on carbon.
417
00:22:30,131 --> 00:22:32,616
The carbon-based molecules
we call proteins,
418
00:22:32,667 --> 00:22:34,835
the molecules of life,
419
00:22:34,870 --> 00:22:38,039
contain literally hundreds
of thousands of atoms.
420
00:22:38,073 --> 00:22:42,009
Carbon atoms are the backbone
of the molecules
421
00:22:42,027 --> 00:22:44,245
that make every
living thing on Earth,
422
00:22:44,279 --> 00:22:46,747
including us.
423
00:22:46,782 --> 00:22:50,017
That's the difference between
rocks and living things.
424
00:22:51,686 --> 00:22:54,088
Life can make
enormous molecules
425
00:22:54,122 --> 00:22:56,590
of stunning size
and complexity,
426
00:22:56,592 --> 00:22:58,726
freeing matter to improvise,
427
00:22:58,760 --> 00:23:00,761
evolve,
428
00:23:00,796 --> 00:23:02,797
and even love.
429
00:23:05,984 --> 00:23:08,386
¶ ¶
430
00:23:33,745 --> 00:23:35,780
DEGRASSE TYSON:
Take it easy, Dad.
431
00:23:35,814 --> 00:23:38,215
He never actually touched her.
432
00:23:38,250 --> 00:23:40,351
In everyday life on our world,
433
00:23:40,385 --> 00:23:41,986
on the scale of atoms,
434
00:23:42,020 --> 00:23:45,890
material objects
never really touch.
435
00:23:45,924 --> 00:23:49,326
Each atom has a tiny
nucleus at its center,
436
00:23:49,361 --> 00:23:52,730
surrounded by an electron cloud
of lines of force.
437
00:23:52,764 --> 00:23:55,232
As the atoms
approach each other,
438
00:23:55,267 --> 00:23:57,201
the boy's electron clouds
439
00:23:57,235 --> 00:23:58,803
push away the girl's.
440
00:23:58,837 --> 00:24:02,973
More than 99.9%
of the matter of any atom
441
00:24:03,008 --> 00:24:05,176
is concentrated in its nucleus.
442
00:24:05,210 --> 00:24:08,646
The nucleus is surrounded
by an electron cloud
443
00:24:08,680 --> 00:24:11,048
which produces
an invisible field of force
444
00:24:11,082 --> 00:24:13,350
and acts like a shock absorber.
445
00:24:13,385 --> 00:24:16,020
The configuration
of the electron cloud
446
00:24:16,054 --> 00:24:18,022
determines the nature
of an element.
447
00:24:18,056 --> 00:24:20,691
In the ordinary course
of things here on Earth,
448
00:24:20,725 --> 00:24:22,593
the nuclei never touch.
449
00:24:22,627 --> 00:24:24,695
We have a sensation
of touching,
450
00:24:24,729 --> 00:24:27,331
but that's really just
our invisible force fields
451
00:24:27,365 --> 00:24:30,301
overlapping and repelling
each other.
452
00:24:46,084 --> 00:24:48,552
The nucleus is very small
453
00:24:48,554 --> 00:24:50,187
compared to the rest
of the atom.
454
00:24:50,222 --> 00:24:54,225
If an atom were the size
of this cathedral,
455
00:24:54,259 --> 00:24:58,496
its nucleus would be the size
of that mote of dust.
456
00:25:01,266 --> 00:25:05,469
An atom is mostly empty space.
457
00:25:05,504 --> 00:25:08,205
To understand
the nature of matter,
458
00:25:08,240 --> 00:25:10,207
we have to go deeper still,
459
00:25:10,242 --> 00:25:13,244
to a place 100,000 times smaller
than the atom:
460
00:25:13,278 --> 00:25:15,279
its nucleus.
461
00:25:18,450 --> 00:25:20,217
The simplest and
most plentiful atom
462
00:25:20,252 --> 00:25:22,887
in the cosmos is hydrogen.
463
00:25:22,921 --> 00:25:25,122
Its nucleus is a single proton,
464
00:25:25,156 --> 00:25:28,158
which makes hydrogen
element number one.
465
00:25:28,193 --> 00:25:29,994
The clouds that surround it
466
00:25:30,028 --> 00:25:32,396
are the realms where
the atom's lone electron
467
00:25:32,430 --> 00:25:34,965
is permitted to roam.
468
00:25:35,000 --> 00:25:38,235
What happens when you have
a nucleus with two protons?
469
00:25:38,270 --> 00:25:39,904
Protons repel each other.
470
00:25:39,938 --> 00:25:42,273
In order to hold them together
in a nucleus,
471
00:25:42,307 --> 00:25:45,476
you need other particles
called neutrons.
472
00:25:45,510 --> 00:25:48,078
Their job is
to keep the protons
473
00:25:48,113 --> 00:25:49,513
from getting out of line.
474
00:25:49,548 --> 00:25:51,649
They overwhelm the protons
475
00:25:51,683 --> 00:25:54,518
with their strong attractive
nuclear force.
476
00:25:54,553 --> 00:25:57,788
A nucleus with two protons
is element number two,
477
00:25:57,822 --> 00:26:00,457
otherwise known as helium.
478
00:26:00,492 --> 00:26:03,494
A nucleus with six protons
is element number six,
479
00:26:03,528 --> 00:26:05,462
which is carbon,
480
00:26:05,464 --> 00:26:08,599
the fundamental
building block of life.
481
00:26:08,633 --> 00:26:11,769
The nucleus of a gold atom
has 79 protons.
482
00:26:11,803 --> 00:26:13,804
They attract 79 electrons
483
00:26:13,838 --> 00:26:15,639
in clouds around it.
484
00:26:15,674 --> 00:26:17,942
The way light interacts
with those electrons
485
00:26:17,976 --> 00:26:20,544
is what makes gold glitter.
486
00:26:20,579 --> 00:26:23,514
Every additional proton
in the nucleus
487
00:26:23,548 --> 00:26:26,817
requires enough neutrons
to bind them together...
488
00:26:26,851 --> 00:26:28,485
up to a point.
489
00:26:28,520 --> 00:26:30,721
There's an upper limit
to the number of neutrons
490
00:26:30,723 --> 00:26:32,489
you can stuff ininto a nucleus
491
00:26:32,491 --> 00:26:34,258
before it becomes unstable.
492
00:26:34,260 --> 00:26:36,427
I know a place
493
00:26:36,429 --> 00:26:38,495
where the nuclei
of different atoms
494
00:26:38,497 --> 00:26:40,497
actually do touch each other.
495
00:27:00,552 --> 00:27:03,053
The Sun looks like
a solid object,
496
00:27:03,055 --> 00:27:05,255
but it's not.
497
00:27:05,257 --> 00:27:08,192
It's so hot that all its atoms
498
00:27:08,194 --> 00:27:10,094
are always in
their gaseous state.
499
00:27:10,096 --> 00:27:11,528
The bonds that join atoms
500
00:27:11,530 --> 00:27:13,297
to make solids
and liquids on Earth
501
00:27:13,299 --> 00:27:15,199
are not strong enough
to withstand
502
00:27:15,201 --> 00:27:18,168
the heat of the broiling Sun.
503
00:27:18,170 --> 00:27:21,038
Those arcing streams
of incandescent gas
504
00:27:21,040 --> 00:27:23,240
that dwarf the Earth
505
00:27:23,242 --> 00:27:25,376
are guided by
magnetic lines of force
506
00:27:25,378 --> 00:27:28,445
that emanate from below
the surface of the Sun.
507
00:27:28,447 --> 00:27:30,981
Why is the Sun so hot?
508
00:27:30,983 --> 00:27:33,283
Because its own
stupendous gravity
509
00:27:33,285 --> 00:27:35,719
is squeezing
its atoms together.
510
00:27:38,089 --> 00:27:40,724
The energy of gravity
is being transformed
511
00:27:40,726 --> 00:27:42,860
into the energy
of moving atoms.
512
00:27:42,862 --> 00:27:45,562
That's what heat is.
513
00:27:45,564 --> 00:27:47,431
The deeper we go into the Sun,
514
00:27:47,433 --> 00:27:49,233
the greater the squeezing
515
00:27:49,235 --> 00:27:51,502
and the higher the temperature.
516
00:27:51,504 --> 00:27:53,070
In the heart of the Sun,
517
00:27:53,072 --> 00:27:54,905
the atoms are moving so fast
518
00:27:54,907 --> 00:27:57,274
that when they collide,
they fuse.
519
00:27:57,276 --> 00:28:00,911
Their nuclei touch.
520
00:28:00,913 --> 00:28:04,348
The Sun is a nuclear
fusion reactor,
521
00:28:04,350 --> 00:28:06,617
held together
by its own gravity.
522
00:28:06,619 --> 00:28:09,953
It's balanced between
the inward pull of gravity
523
00:28:09,955 --> 00:28:12,589
and the outward push
of its hot gases.
524
00:28:16,528 --> 00:28:19,830
That balance has lasted
billions of years,
525
00:28:19,864 --> 00:28:21,799
providing stability
that made possible
526
00:28:21,833 --> 00:28:23,333
the evolution of life on Earth.
527
00:28:23,368 --> 00:28:25,769
In the Sun's core,
528
00:28:25,804 --> 00:28:27,671
the fusion of hydrogen
into helium
529
00:28:27,706 --> 00:28:30,874
releases nuclear energy
in the form of photons.
530
00:28:30,876 --> 00:28:32,509
These particles of light
531
00:28:32,544 --> 00:28:34,445
slowly work their way
to the surface,
532
00:28:34,479 --> 00:28:36,180
where they're seen as sunlight.
533
00:28:36,214 --> 00:28:40,117
Helium is the ash
of the Sun's nuclear furnace.
534
00:28:42,120 --> 00:28:43,954
The Sun is a medium-sized star.
535
00:28:43,988 --> 00:28:47,591
Its core is only a lukewarm
ten million degrees--
536
00:28:47,625 --> 00:28:48,926
hot enough to fuse hydrogen,
537
00:28:48,960 --> 00:28:50,928
but too cold to fuse helium.
538
00:28:50,962 --> 00:28:53,330
There are many stars
in the galaxy
539
00:28:53,364 --> 00:28:54,932
that get much hotter,
540
00:28:54,966 --> 00:28:56,467
because they're more massive
541
00:28:56,501 --> 00:28:58,035
and have more gravity.
542
00:28:58,069 --> 00:29:01,205
Such stars fuse helium
into heavier elements,
543
00:29:01,239 --> 00:29:03,173
like carbon and oxygen.
544
00:29:03,208 --> 00:29:05,109
In their old age,
545
00:29:05,143 --> 00:29:07,811
they gently diffuse
these elements into space.
546
00:29:10,215 --> 00:29:12,382
Other stars, more massive yet,
547
00:29:12,400 --> 00:29:14,685
live fast and die young
548
00:29:14,719 --> 00:29:16,720
in cataclysmic
supernova explosions.
549
00:29:16,722 --> 00:29:19,823
In our galaxy,
such stars go supernova
550
00:29:19,924 --> 00:29:21,325
about once a century.
551
00:29:21,359 --> 00:29:23,727
(explosions rumbling)
552
00:29:23,762 --> 00:29:26,396
These explosions are far hotter
than the core of the Sun--
553
00:29:26,431 --> 00:29:29,333
hot enough to transform
elements like iron
554
00:29:29,367 --> 00:29:31,635
into all the heavier ones
555
00:29:31,736 --> 00:29:34,905
and spew them into space.
556
00:29:34,939 --> 00:29:36,807
The Large Magellanic Cloud
557
00:29:36,841 --> 00:29:39,009
is a neighboring galaxy
of our Milky Way.
558
00:29:39,043 --> 00:29:41,678
It's visible in the skies
of the Southern Hemisphere.
559
00:29:42,781 --> 00:29:44,348
When a supernova explodes,
560
00:29:44,382 --> 00:29:45,916
its brightness rivals
561
00:29:45,950 --> 00:29:49,286
that of its entire galaxy.
562
00:29:59,030 --> 00:30:02,166
But all that light
is only about one percent
563
00:30:02,200 --> 00:30:04,835
of the energy
liberated in the explosion.
564
00:30:04,869 --> 00:30:07,938
The rest of the energy is
carried off by the most common
565
00:30:07,972 --> 00:30:10,274
and the most mysterious
particles in the cosmos.
566
00:30:10,308 --> 00:30:13,677
There are trillions of them
passing through you right now,
567
00:30:13,711 --> 00:30:16,213
and yet tracking down
even one of them
568
00:30:16,247 --> 00:30:19,883
will take us to one of
the strangest places on Earth.
569
00:30:26,441 --> 00:30:28,509
DEGRASSE TYSON:
Stalking the wild neutrino
570
00:30:28,543 --> 00:30:30,344
is the rarest of sport.
571
00:30:30,378 --> 00:30:32,913
The lengths one must go
to track them down
572
00:30:32,947 --> 00:30:34,681
is nothing short
of astonishing.
573
00:30:34,716 --> 00:30:38,352
Welcome to Super-Kamiokande,
574
00:30:38,386 --> 00:30:42,189
the subterranean Japanese
neutrino detection chamber.
575
00:30:42,223 --> 00:30:45,359
We're more than a half mile
beneath Earth's surface.
576
00:30:45,393 --> 00:30:47,628
You might ask,
"Well, who in their right mind
577
00:30:47,662 --> 00:30:50,864
would bury an astronomical
observatory so far underground?"
578
00:30:50,899 --> 00:30:54,434
Those who hunt the most elusive
prey in the cosmos:
579
00:30:54,469 --> 00:30:56,436
the neutrino.
580
00:30:56,471 --> 00:30:58,438
This enormous array
of light detectors
581
00:30:58,473 --> 00:31:01,508
surrounding 50,000 tons
of distilled water
582
00:31:01,543 --> 00:31:05,012
is a trap designed
to catch neutrinos only.
583
00:31:05,046 --> 00:31:07,447
Other particles,
such as cosmic rays--
584
00:31:07,482 --> 00:31:10,450
mostly protons and electrons
that rain down from space--
585
00:31:10,485 --> 00:31:13,053
cannot get through
all that rock above us.
586
00:31:13,087 --> 00:31:16,456
But matter poses no obstacle
to a neutrino.
587
00:31:16,491 --> 00:31:20,494
A neutrino could pass through
100 light-years of steel
588
00:31:20,528 --> 00:31:22,963
without even slowing down.
589
00:31:22,997 --> 00:31:25,699
Neutrinos hardly interact
with matter at all.
590
00:31:25,733 --> 00:31:27,401
That's why you need
so much of it
591
00:31:27,435 --> 00:31:29,002
to catch even one of them.
592
00:31:29,037 --> 00:31:31,071
On those rare occasions
when a neutrino
593
00:31:31,105 --> 00:31:33,840
actually does collide with
a particle of ordinary matter,
594
00:31:33,875 --> 00:31:38,045
it produces a ghostly,
ring-shaped flash of light.
595
00:31:38,079 --> 00:31:40,747
We're lying in wait
596
00:31:40,782 --> 00:31:44,384
for a particle that weighs
next to nothing.
597
00:31:44,386 --> 00:31:46,386
Even the miniscule electron
598
00:31:46,388 --> 00:31:49,289
has more than
a million times its mass...
599
00:31:49,374 --> 00:31:50,991
There!
600
00:31:51,092 --> 00:31:53,193
When the supernova in
the Large Magellanic Cloud
601
00:31:53,294 --> 00:31:55,495
blew its top in 1987,
602
00:31:55,580 --> 00:31:58,498
this is what it would have
looked like in here.
603
00:31:58,533 --> 00:32:00,968
Now remember,
the Large Magellanic Cloud
604
00:32:00,970 --> 00:32:02,302
is in our Southern Hemisphere,
605
00:32:02,304 --> 00:32:03,870
so the neutrinos
didn't come through
606
00:32:03,905 --> 00:32:05,505
that half-mile of rock above us,
607
00:32:05,540 --> 00:32:08,108
they had to pass through
the thousands of miles
608
00:32:08,142 --> 00:32:10,944
of rock and iron below us
to reach this detector.
609
00:32:10,979 --> 00:32:13,614
But the coolest thing
was that those neutrinos
610
00:32:13,648 --> 00:32:16,249
hit Earth three hours before
611
00:32:16,284 --> 00:32:18,285
the light from
the supernova did.
612
00:32:18,319 --> 00:32:20,520
If nothing can travel
faster than light,
613
00:32:20,555 --> 00:32:22,956
how could that possibly be?
614
00:32:28,563 --> 00:32:31,431
This is a dead star walking.
615
00:32:31,466 --> 00:32:34,935
It may look normal,
but deep within it
616
00:32:34,969 --> 00:32:37,404
something cataclysmic
is happening.
617
00:32:37,438 --> 00:32:39,773
This blue supergiant star
618
00:32:39,807 --> 00:32:44,244
has already begun
to explode inside.
619
00:32:47,849 --> 00:32:51,418
Like rats deserting
a sinking ship, the neutrinos
620
00:32:51,452 --> 00:32:53,920
produced in the heart
of the exploding star
621
00:32:53,955 --> 00:32:56,490
race outward
at near the speed of light,
622
00:32:56,524 --> 00:32:58,892
through overlying mass
623
00:32:58,926 --> 00:33:00,494
in only a few seconds.
624
00:33:00,528 --> 00:33:02,729
But the shock wave
of the exploding gas
625
00:33:02,764 --> 00:33:05,766
plods along from the center
of the star
626
00:33:05,800 --> 00:33:08,402
at 1/10,000
the speed of light
627
00:33:08,436 --> 00:33:10,637
until it finally reaches
628
00:33:10,672 --> 00:33:12,105
the star's surface,
629
00:33:12,140 --> 00:33:15,876
turning it into Supernova 1987A.
630
00:33:17,478 --> 00:33:21,948
(explosion thundering,
rumbling)
631
00:33:21,983 --> 00:33:23,650
It took hours for the explosion
632
00:33:23,685 --> 00:33:26,253
to reach the surface of the star
and blow it wide open,
633
00:33:26,287 --> 00:33:28,088
exposing the superhot core.
634
00:33:28,122 --> 00:33:31,158
The neutrinos had
an insurmountable head start.
635
00:33:31,192 --> 00:33:33,977
That's why the flash of light
arrived on Earth
636
00:33:34,028 --> 00:33:36,997
so much later
than the shower of neutrinos.
637
00:33:37,031 --> 00:33:40,467
Before anyone had ever snared
the wild neutrino,
638
00:33:40,501 --> 00:33:44,371
it existed in the mind
of a theoretical physicist.
639
00:33:44,405 --> 00:33:47,441
Just as Charles Darwin knew
640
00:33:47,475 --> 00:33:50,043
there must be
an extremely long-nosed creature
641
00:33:50,078 --> 00:33:52,045
flying around somewhere
in Madagascar,
642
00:33:52,080 --> 00:33:55,916
a 20th-century physicist
named Wolfgang Pauli...
643
00:33:58,920 --> 00:34:00,854
...was desperately seeking
a particle
644
00:34:00,888 --> 00:34:03,156
to rescue one of the pillars of
modern physics,
645
00:34:03,191 --> 00:34:06,526
the Law of the Conservation
of Energy.
646
00:34:15,369 --> 00:34:17,404
So why didn't I flinch?
647
00:34:17,438 --> 00:34:19,706
Because the laws of science
differ fundamentally
648
00:34:19,741 --> 00:34:21,541
from those
of other human endeavors.
649
00:34:21,576 --> 00:34:25,078
In order for an idea
to become a scientific law,
650
00:34:25,113 --> 00:34:26,913
it has to unbreakable.
651
00:34:26,948 --> 00:34:29,683
That's why I was willing
to bet this face
652
00:34:29,717 --> 00:34:32,586
on the Laws of Conservation
of Energy.
653
00:34:32,620 --> 00:34:35,021
Now, if you try this at home,
654
00:34:35,056 --> 00:34:38,024
take care not to give
the cannonball a push.
655
00:34:38,042 --> 00:34:39,659
That's adding energy,
656
00:34:39,694 --> 00:34:42,229
and the ball will surely
come back and do some damage.
657
00:34:42,263 --> 00:34:45,265
You just have
to let it go, like this.
658
00:34:46,467 --> 00:34:47,768
By lifting the ball,
659
00:34:47,802 --> 00:34:49,503
you give it
gravitational energy,
660
00:34:49,537 --> 00:34:52,506
which is the potential
to fall and accelerate.
661
00:34:52,540 --> 00:34:54,074
The cannonball is going fastest
662
00:34:54,108 --> 00:34:55,742
when it's at the bottom
of its arc,
663
00:34:55,777 --> 00:34:57,410
and at that moment,
664
00:34:57,445 --> 00:34:59,613
it's converted all
of its gravitational energy
665
00:34:59,647 --> 00:35:01,681
to the energy of motion.
666
00:35:01,716 --> 00:35:04,384
As it swings, the cannonball
is constantly exchanging
667
00:35:04,418 --> 00:35:06,620
one of these two kinds of energy
for the other,
668
00:35:06,654 --> 00:35:09,856
but the total amount of energy
remains constant.
669
00:35:09,891 --> 00:35:13,226
That's an example of the
Law of Conservation of Energy.
670
00:35:13,261 --> 00:35:15,762
Once the cannonball is released,
671
00:35:15,764 --> 00:35:18,765
it can never gain more energy
than it had to begin with.
672
00:35:18,800 --> 00:35:22,102
It has no way to fly up
and break my nose.
673
00:35:22,136 --> 00:35:26,106
The energy accounting books
are always strictly balanced.
674
00:35:26,140 --> 00:35:28,475
There's no such thing
as cheating.
675
00:35:28,509 --> 00:35:30,310
So in the 20th century,
676
00:35:30,344 --> 00:35:33,713
when physicists first calculated
the energy of atoms precisely,
677
00:35:33,748 --> 00:35:34,981
they were startled to discover
678
00:35:35,016 --> 00:35:37,517
an apparent violation
of this law.
679
00:35:39,620 --> 00:35:42,088
They found that in
some radioactive atoms,
680
00:35:42,123 --> 00:35:45,492
the nucleus can spontaneously
eject an electron.
681
00:35:45,510 --> 00:35:49,062
This transforms the atom
into a different element.
682
00:35:49,064 --> 00:35:51,631
The physicists were mystified.
683
00:35:51,666 --> 00:35:53,733
The energy
of the escaped electron
684
00:35:53,768 --> 00:35:55,735
plus that of the new element
685
00:35:55,770 --> 00:35:59,072
adds up to less than the energy
in the original nucleus.
686
00:35:59,106 --> 00:36:00,974
But the law says,
687
00:36:00,976 --> 00:36:03,910
"Thou shall not destroy
or create energy."
688
00:36:03,945 --> 00:36:06,780
So where did
the missing energy go?
689
00:36:06,814 --> 00:36:08,949
In 1930...
690
00:36:08,983 --> 00:36:11,518
Wolfgang Pauli predicted
691
00:36:11,552 --> 00:36:13,653
there must be
an undiscovered particle,
692
00:36:13,688 --> 00:36:16,122
one that makes off
with the missing energy.
693
00:36:16,157 --> 00:36:18,925
At the time, Pauli lamented
694
00:36:18,960 --> 00:36:22,362
that such a phantom particle
might be so minute,
695
00:36:22,396 --> 00:36:24,297
swift and evasive
696
00:36:24,299 --> 00:36:27,367
as to forever defy detection.
697
00:36:27,401 --> 00:36:30,804
But that was a rare failure
of his imagination
698
00:36:30,838 --> 00:36:33,006
because science
is always searching
699
00:36:33,040 --> 00:36:34,875
for a way to go deeper still.
700
00:36:34,909 --> 00:36:36,810
A generation later,
701
00:36:36,844 --> 00:36:39,162
Pauli's neutrinos were actually
detected for the first time
702
00:36:39,213 --> 00:36:41,781
in radiation
from a nuclear reactor.
703
00:36:41,816 --> 00:36:45,719
And we've been finding them,
with difficulty, ever since.
704
00:36:45,753 --> 00:36:48,622
There are scientists today
705
00:36:48,624 --> 00:36:51,892
who are trying to find a way
to ride those neutrinos
706
00:36:51,926 --> 00:36:55,428
all the way back
to the beginning of time.
707
00:36:56,931 --> 00:36:58,798
We'll go as far
as they have gone
708
00:36:58,833 --> 00:37:02,769
to come up
against the wall of forever.
709
00:37:08,476 --> 00:37:11,211
YSON: The wall of
forever is nothing new.
710
00:37:11,245 --> 00:37:13,179
Our ancestors came up
against it
711
00:37:13,214 --> 00:37:16,316
almost as soon as they first
started imagining it.
712
00:37:16,350 --> 00:37:21,121
A million dawns ago,
in the 13th century BC,
713
00:37:21,155 --> 00:37:24,658
the Egyptian this temple
at Abu Simbel
714
00:37:24,692 --> 00:37:26,726
to honor
the Pharaoh Ramses II,
715
00:37:26,761 --> 00:37:29,963
depicted here
in four colossal statues.
716
00:37:29,997 --> 00:37:32,899
Reigning even above
even this mighty king
717
00:37:32,901 --> 00:37:35,902
is the falcon-headed
Ra-Harakhti,
718
00:37:35,937 --> 00:37:38,171
god of the Sun.
719
00:37:42,610 --> 00:37:44,711
The temple was designed
720
00:37:44,778 --> 00:37:46,479
so that the light
from the rising Sun
721
00:37:46,514 --> 00:37:50,817
could only enter the sanctuary
on two days every year.
722
00:37:50,851 --> 00:37:53,853
As the rays enter the temple,
723
00:37:53,888 --> 00:37:55,822
they burnish the statues
of the gods
724
00:37:55,856 --> 00:37:57,490
with their golden light
725
00:37:57,525 --> 00:38:01,494
before penetrating
the sanctuary.
726
00:38:01,529 --> 00:38:05,498
Even then,
one god remains in shadow.
727
00:38:05,533 --> 00:38:08,001
Ptah, Lord of Creation,
728
00:38:08,035 --> 00:38:10,236
as if the origin
of the universe
729
00:38:10,271 --> 00:38:13,106
must forever be concealed.
730
00:38:16,811 --> 00:38:19,613
Feel the Sun on your face.
731
00:38:19,647 --> 00:38:22,215
The energy that warms you
732
00:38:22,249 --> 00:38:25,385
began its journey
some ten million years ago
733
00:38:25,419 --> 00:38:27,504
in the heart of the Sun.
734
00:38:27,555 --> 00:38:30,590
Unlike neutrinos,
735
00:38:30,625 --> 00:38:32,425
the photons needed
736
00:38:32,460 --> 00:38:35,428
that long to work their way out
from the core to the surface.
737
00:38:35,463 --> 00:38:37,464
Why?
738
00:38:37,498 --> 00:38:40,400
Because they were colliding
billions of times per second
739
00:38:40,434 --> 00:38:42,702
with the Sun's atoms,
every collision
740
00:38:42,737 --> 00:38:45,705
sending them off
in a random direction.
741
00:38:45,740 --> 00:38:47,707
But once they finally
reached the surface,
742
00:38:47,742 --> 00:38:49,142
they were free
743
00:38:49,176 --> 00:38:51,878
to dash nonstop,
at the speed of light,
744
00:38:51,912 --> 00:38:54,114
in a mere eight minutes
and 20 seconds
745
00:38:54,148 --> 00:38:55,915
from the Sun to you.
746
00:38:57,652 --> 00:39:00,787
Ten-million-year-old light
on your face.
747
00:39:03,157 --> 00:39:05,425
What was happening
748
00:39:05,459 --> 00:39:08,795
when that light left
the heart of the Sun?
749
00:39:13,701 --> 00:39:16,736
The Cosmic Calendar compresses
750
00:39:16,771 --> 00:39:19,572
the entire
13.8 billion year history
751
00:39:19,607 --> 00:39:21,675
of the universe
into a single year.
752
00:39:21,709 --> 00:39:25,245
Every month represents
about a billion years.
753
00:39:25,279 --> 00:39:28,081
Every day,
about 40 million years.
754
00:39:28,182 --> 00:39:31,418
The universe is so old that,
on the Cosmic Calendar,
755
00:39:31,452 --> 00:39:35,188
ten million years ago
only takes us back as far as...
756
00:39:35,222 --> 00:39:38,825
6:00 p.m. on the last evening
757
00:39:38,859 --> 00:39:41,695
of the last day of the year.
758
00:39:41,729 --> 00:39:43,296
And what about us?
759
00:39:43,330 --> 00:39:45,165
Humans had yet to evolve.
760
00:39:45,199 --> 00:39:46,933
Ten million years ago,
761
00:39:46,967 --> 00:39:49,369
our ancestors
were anthropoid apes,
762
00:39:49,403 --> 00:39:51,304
swinging through
the trees of Africa.
763
00:39:51,338 --> 00:39:54,808
To us, ten million years
seems like a long time,
764
00:39:54,842 --> 00:39:57,210
but it's only the length
of an afternoon
765
00:39:57,244 --> 00:39:59,713
on the timescale of the cosmos.
766
00:40:03,050 --> 00:40:05,652
The Sun began fusing hydrogen
767
00:40:05,686 --> 00:40:07,987
4,500 million years ago--
768
00:40:08,022 --> 00:40:11,725
August 31
on the Cosmic Calendar.
769
00:40:11,759 --> 00:40:13,793
Our Milky Way Galaxy
770
00:40:13,828 --> 00:40:16,896
is about
10,000 million years old.
771
00:40:16,931 --> 00:40:22,001
The first galaxies formed about
a few billion years earlier.
772
00:40:22,036 --> 00:40:25,972
Something keeps me from going
any further back in time.
773
00:40:26,006 --> 00:40:28,007
What is this?
774
00:40:31,679 --> 00:40:33,546
It's the nature of light
and time.
775
00:40:33,581 --> 00:40:36,750
Because light travels
at a finite speed,
776
00:40:36,784 --> 00:40:39,052
to look across space
777
00:40:39,086 --> 00:40:41,755
is to look back in time.
778
00:40:44,692 --> 00:40:46,826
So the farther we see,
779
00:40:46,861 --> 00:40:49,662
the older the light.
780
00:40:49,697 --> 00:40:52,499
This is as far back
in the history of the cosmos
781
00:40:52,533 --> 00:40:54,501
as we can see with light.
782
00:40:54,535 --> 00:40:56,936
It's a baby picture of universe,
783
00:40:56,971 --> 00:41:00,039
when it was
only 380,000 years old.
784
00:41:00,074 --> 00:41:03,843
That's 15 minutes
into January 1
785
00:41:03,878 --> 00:41:05,712
on the Cosmic Calendar.
786
00:41:05,746 --> 00:41:08,882
If we look as far as we can see
in any direction
787
00:41:08,916 --> 00:41:10,884
using microwave telescopes,
788
00:41:10,918 --> 00:41:12,352
this is what we see,
789
00:41:12,386 --> 00:41:15,688
the glow left over
from the Big Bang.
790
00:41:15,723 --> 00:41:17,690
Imagine that
all the matter and energy
791
00:41:17,725 --> 00:41:19,592
of the observable universe
792
00:41:19,627 --> 00:41:21,361
was concentrated into something
793
00:41:21,395 --> 00:41:23,897
no larger than this.
794
00:41:23,931 --> 00:41:27,801
That's the size of the universe
795
00:41:27,835 --> 00:41:30,203
when it was a trillionth
of a trillionth
796
00:41:30,237 --> 00:41:33,206
of a trillionth of a second old.
797
00:41:33,240 --> 00:41:36,776
All the matter and energy
of the hundred billion galaxies
798
00:41:36,811 --> 00:41:39,879
now splayed out across
the billions of light-years
799
00:41:39,914 --> 00:41:41,881
were once pent up
800
00:41:41,916 --> 00:41:44,250
in something
the size of a marble.
801
00:41:44,285 --> 00:41:46,319
Can you imagine how
tightly packed
802
00:41:46,353 --> 00:41:48,221
that marble must have been?
803
00:41:48,255 --> 00:41:51,090
Far too dense for any kind
of light to move through it,
804
00:41:51,125 --> 00:41:54,894
but no obstacle
for the likes of neutrinos.
805
00:41:54,929 --> 00:41:57,797
The Big Bang must have produced
stupendous numbers of neutrinos,
806
00:41:57,832 --> 00:41:59,399
which flew unhindered
807
00:41:59,433 --> 00:42:01,501
through that inconceivable crush
of matter.
808
00:42:01,535 --> 00:42:04,737
The very thing that makes them
almost impossible to detect
809
00:42:04,772 --> 00:42:08,842
is what allows neutrinos
to sail through the curtain
810
00:42:08,876 --> 00:42:11,511
that conceals
the beginning of time.
811
00:42:11,545 --> 00:42:13,112
Where are they now?
812
00:42:13,147 --> 00:42:14,681
They are here, they're there,
813
00:42:14,715 --> 00:42:16,916
everywhere throughout
the universe.
814
00:42:16,951 --> 00:42:19,786
Neutrinos from creation
are within you.
815
00:42:20,855 --> 00:42:23,089
From a marble...
816
00:42:23,123 --> 00:42:25,124
to the cosmos.
817
00:42:35,870 --> 00:42:39,172
This is the road that Thales
and Democritus put us on
818
00:42:39,206 --> 00:42:41,975
some 2,500 years ago--
819
00:42:42,009 --> 00:42:44,043
a road of endless searching,
820
00:42:44,078 --> 00:42:47,380
a relentless, systematic hunt
for new worlds
821
00:42:47,414 --> 00:42:50,049
and an ever-deepening
understanding of nature.
822
00:42:51,518 --> 00:42:54,387
Who among you
will pick up that torch
823
00:42:54,421 --> 00:42:58,024
and take us down
that next stretch of road?
824
00:43:01,662 --> 00:42:58,024
Captioned by
Media Access Group at WGBH
access.wgbh.org