We live on one level of existence, but there are others.
These hidden dimensions of reality are everywhere.
Far away, across the light years.
Beneath our feet.
And even inside you and me.
We are made of atoms.
There are more atoms in your eye,
than there are stars and all the galaxies of the known universe.
The same is true of any solid object
larger than the tip of your little finger.
I'm a collection of three billion, billion, billion
intricately arranged atoms called Neil Degrasse Tyson.
You are a similar collection with a different name.
We don't usually think of ourselves this way
because that level of reality lies beyond the realm of our senses.
But we're not gonna let that stop us.
We can go deeper into the wonder.
Atoms let matter do funny things.
To understand water, you need to know what its atoms are doing.
Every molecule of water is composed
of two tiny hydrogen atoms
attached to a larger oxygen atom.
That's why we call it H20.
If it's not too hot or too cold,
the molecules can slide and tumble past each other.
There's still some stickiness between the molecules,
but not enough to lock them into a rigid solid.
That's what makes something a liquid.
The sun warms the water.
And with more energy,
the molecules move faster.
That's all that temperature is.
Those molecules are moving fast enough
to break the weak bonds that hold them to their neighbors.
That's evaporation.
The air we breathe is made of
nitrogen and oxygen molecules
with a scattering of water vapor and carbon dioxide.
Incoming!
That's condensation.
A dewdrop is the momentary triumph
of condensation over evaporation.
And while it lasts,
it's a little cosmos with its own worlds...
creatures, drama.
To explore the far-flung realms
of this dewdrop,
we're gonna need a ship.
One with twin engines...
science and imagination.
That's a single-celled paramecium,
one of a multitude of skilled hunter-warriors
that roam the dewdrop.
But they, too, are hunted.
The Dileptus. The paramecium's mortal enemy.
The paramecium might get lucky and score a direct hit.
Even if it doesn't,
the recoil from the barrage will put some distance
between the paramecium and its attacker.
What can I say?
That's life in the dewdrop.
That little guy is tardigrade,
an animal smaller than the head of a pin.
Don't underestimate them.
Tardigrades have been living on this planet
a lot longer than we have.
About 500 million years.
For every one of us,
there's at least a billion of them.
They can make a living anywhere on earth.
In the frigid peaks of the tallest mountains,
in the cauldrons of erupting volcanoes,
and in the deep ocean vents at the bottom of the sea.
Tardigrades are so tough,
they can survive naked
in the vacuum of space.
They've survived all five
of the most recent mass extinctions on this planet.
A visitor from another world could be forgiven
for thinking of earth as the planet of the tardigrades.
If we're ever gonna get to the bottom of this dewdrop,
better get a move on.
Every leaf and tiny clump of moss
has hundreds of thousands
of microscopic mouths called Stomata.
Plants breathe through them,
taking in carbon dioxide
and exhaling the oxygen that we need to live.
The plants can survive without us.
But we and all the other animals...
we'd be toast without them.
The plants make food out of sunlight.
We animals can't do that.
To see how they do it,
we have to go deeper,
make ourselves about a thousand times smaller
to get into their treasure house,
the place where they keep the good stuff...
the chlorophyll.
That's the molecule
that converts sunlight into energy.
Every one of those rectangles is a plant cell.
And those tiny green vehicles
are its energy factories.
If we could steal their trade secrets,
it would trigger a new industrial revolution.
But to spy on them,
we're gonna need to go deeper still.
What alien world has the ship of the imagination
carried us to this time?
It's the cosmos...
Contained within a dewdrop.
We're on an industrial espionage mission.
If we can penetrate the trade secrets
of the manufacturing process in that chloroplast,
let's just say our whole future hangs in the balance.
This chloroplast is using sunlight
to break water molecules
into atoms of hydrogen and oxygen.
It combines the hydrogen with carbon dioxide
to make sugar,
and releases the oxygen as a waste product.
To see how it happens, we have to go even deeper,
get even smaller.
We're talking atomic scale.
Bingo.
This assembly line is the heart
of the molecular industrial complex.
At the molecular level,
things happen too fast for us to see.
So we'll have to slow them down
about a billion times.
Those larger molecules are carbon dioxide.
Each one of them is made
of one carbon and two oxygen atoms.
When sunlight strikes a green molecule of chlorophyll,
it sets in motion a series of chemical reactions,
breaking apart water molecules
and freeing energetic electrons.
And that's just the day shift,
when sunlight supplies the incoming stream of energy.
There's a second shift that works day and night
using the solar energy kept in reserve.
The energy of the free electrons is put to work,
combining carbon dioxide with hydrogen from the water.
The end product is sugar, which stores the solar energy.
The chloroplast is a three-billion-year-old
solar energy collector.
This sub-microscopic solar battery
is what drives all the forests and the fields
and the plankton of the seas.
And the animals.
Including us.
The solar-powered biosphere
collects and processes six times more power
than our entire civilization.
We understand on a chemical level
how photosynthesis works.
We can recreate the process in a laboratory.
But we're not as good at it as plants are.
And it's not surprising,
considering nature has been at this for billions of years,
and we've only just started.
But if we could figure out
the trade secrets of photosynthesis,
every of other source of energy
we depend on today...
coal, oil, natural gas...
would become obsolete.
Photosynthesis is the ultimate green power.
It doesn't pollute the air
and is, in fact, carbon neutral.
Artificial photosynthesis on a big enough scale
could reduce the greenhouse effect
that's driving climate change in a dangerous direction.
Uh-oh, place is evaporating.
Time to get out of here.
How fleeting is the life of a dewdrop.
It condenses from thin air in the cool of the night,
only to vanish with the heat of the day.
And what of its inhabitants, the tardigrades?
They'll be fine.
They can go without water for years.
It's hard to imagine,
but plants covered the surface of the earth
for hundreds of millions of years
before they put forth their first flower.
That was about a hundred million years ago,
shortly before the dinosaurs were wiped out.
Our world must've been a relatively drab-looking place back then,
dominated by shades of green and brown.
Yeah, there were giant trees and ferns and other plant life,
but not the purple of an iris
or the crimson of a red, red rose.
Orchids were among the first flowering species
to appear on earth, and they're the most diverse.
Darwin was particularly fascinated
by the comet orchid of Madagascar,
a flower whose pollen is hidden at the bottom
of a very long, thin spur.
There can be no stronger test of an idea
than its predictive power.
On the basis of his theory of evolution
through natural selection,
Darwin speculated that somewhere
on the island of Madagascar, there must live flying insects
with extraordinarily lengthy tongues,
ones long enough to reach the pollen.
No one had ever seen such a beast there,
but Darwin insisted
that an animal fitting this description must exist.
Few people at the time believed him.
It wasn't until more than 50 years later
that Darwin was proven right.
In 1903, a huge hawk moth, called the Morgan's sphinx
was discovered in Madagascar.
Attracted by the Comet Orchid's scent,
the moth slurps its pollen with its foot-long tongue,
exactly as Darwin expected it would.
It's even more amazing that the Morgan's sphinx was discovered
when you consider that more than 90%
of Madagascar's rain forest had been destroyed.
In the years since Darwin's famous prediction,
this moth species could have easily become extinct
with all the others...
every one of them a unique phrase of life's poetry,
written in the atoms by eons of evolution.
Ah, the fragrance of lilacs.
It's one of those scents
that triggers a whole constellation of associations,
all those junes of long ago.
But how does that happen?
How does a smell prompt a movie to start running in your head?
It's not something we can see.
Could it be a wave of energy, like light?
Or is it some kind of microscopic particle?
It's actually a molecule.
Every odor we can sense, whether it comes from burnt toast,
gasoline, or a field of lilacs,
is a cloud of molecules.
These molecules have particular shapes.
When I inhale them,
they stimulate a particular set of receptor cells in my nose.
An electrical signal then travels to my brain,
which identifies the scent as lilac.
Other scents are carried by different molecules
with different shapes.
But when I smell a flower or the smoke from a campfire
or the grease from a motor gear,
I'm often flooded with memories.
Why is it that a simple thing such as the scent of a flower
can trigger powerful memories?
It has to do with the way our brains have evolved.
Our sense of smell kicks in
when the olfactory nerve in our brain is stimulated.
That nerve is located very close to the amygdala,
a structure that is integral to our experience of emotion.
It's also very close to the Hippocampus,
which helps us form memories.
The network of neurons that carry the scent signal
from my nose to my brain has been fine-tuned
over hundreds of millions of years of evolution.
It's a survival mechanism that can alert us
to danger or guide us to safety.
If you you can detect the predator
before he's near enough to strike,
or the fire before it traps you in the forest,
you have a much better chance to survive
and pass on your genes to the next generation.
That lovely scent from this field of flowers
sets off a unique combination of nerve signals.
Only that exact combination can crack the safe
where the memory of lilacs is stored inside my brain.
Wonder who they're for.
Maybe we'll find out later.
But first, there's another hidden cosmos waiting for us.
The plants are softly breathing,
inhaling molecules of carbon dioxide
and exhaling molecules of oxygen.
And I'm doing the opposite.
Unlike snowflakes and fingerprints,
atoms or molecules of the same kind
are utterly identical to one another.
With every breath we take,
we inhale as many molecules as there are stars
in all the galaxies in the visible universe.
And every breath we exhale is circulated through the air,
and mixed gradually across the continents,
it becomes available for others to breathe.
Breathe with me.
We all just inhaled about 100 million molecules
that once passed through the lungs of everyone
who ever lived before us.
Think of it... This kind of atomic reincarnation
is another link to our distant ancestors,
including those who first launched us on our explorations
of the unseen universes.
These universes are as real as you or me,
and they surround us.
There was a moment when we awakened
to a new way of thinking and seeing.
It happened about 2,500 years ago
on the Greek islands that lie
between the empires of the east and west.
There, merchants, tourists and sailors freely mingled,
exchanging tales of great kings and gods.
In Ionian cities and towns like Miletus, in what is now Turkey,
the most fundamental elements
of the way we live now first appeared.
Here, for the first time, reenactments of aspects of life
created and executed by professionals
with the expectation of touching something deep
within the hearts of the audience,
or just making them laugh...
The first plays, dramas and comedies, were performed.
Here also was born a radical new idea...
Government by the people.
The first inklings, imperfect then as now, of a democracy,
and the notion that the ordinary citizen
might possess certain rights,
come to us from this time and place.
But in my view, the most revolutionary innovation of all
to come to us from this ancient world was the idea
that natural events were neither punishment nor reward
from capricious gods.
The workings of nature could be explained
without invoking the supernatural.
The first person to express this thought
was a man named Thales.
When the thunder clapped or the earth quaked,
it was not because something you did had somehow displeased
the very demanding gods.
No, it was the result of natural processes
that we were capable of understanding.
Though none of the books he is said to have written survive,
Thales kindled a flame that still burns to this day:
The very idea of cosmos out of chaos,
a universe governed by the order of natural laws
that we can actually figure out.
This is the epic adventure that began in the mind of Thales.
Only a century following Thales' death,
another genius came along.
And he, more than any other,
was the first to discover the existence
of the hidden universes that surround us.
Democritus of Abdera was a true scientist,
a man with a passionate desire to know the cosmos
and to have fun.
This is the man who once said, "a life without parties
would be like an endless road without an end."
You mean, that's it?
That's all there is?
Just a bunch of atoms in a void?
Yep.
Well, think about it.
The world has to be made
of countless indivisible particles in a void.
Otherwise, nothing could move or grow, be divided or changed.
Without atoms
and empty space for them to move in,
the world would be solid ,static and dead.
So, don't be sad, my friends.
Just think of the infinite possibilities
that arise from different arrangements of those atoms.
Here's to the atoms
in this cup and in this wine...
And to the laughter they make possible.
Dispersed through the Clay of the cup
are microscopic mineral grains,
different kinds of crystals,
each with its own distinctive atomic architecture.
Mineral structures are exquisite,
but they have a limited repertoire.
A grain of quartz is a lattice of the same three atoms
repeated, without variation, over and over again.
Even a relatively complex mineral lattice like topaz,
composed of ten or so atoms,
can only repeat the identical atomic structure
again and again.
To lift a matter into another dimension
to free it from the lattice prison of endless repetition,
you need an atom that can bond in all directions
with other atoms like itself
as well as with atoms of different kinds.
Behold the carbon atom...
the essential element for life on earth.
Why?
Carbon is special because it can bond with
up to four other atoms at a time.
It can connect with many different kinds of atoms,
as well as other carbon atoms.
It can curl into rings
and string together into chains,
building molecules far more complex than any crystal.
No other atom has the same flexibility.
Even atoms that have similar chemical properties,
like silicon,
can't form the amazing variety of molecules
built on carbon.
The carbon-based molecules we call proteins,
the molecules of life,
contain literally hundreds of thousands of atoms.
Carbon atoms are the backbone of the molecules
that make every living thing on earth,
including us.
That's the difference between rocks and living things.
Life can make enormous molecules
of stunning size and complexity,
freeing matter to improvise,
evolve,
and even love.
Take it easy, dad.
He never actually touched her.
In everyday life on our world,
on the scale of atoms,
material objects never really touch.
Each atom has a tiny nucleus at its center,
surrounded by an electron cloud of lines of force.
As the atoms approach each other,
the boy's electron clouds
push away the girl's.
More than 99.9% of the matter of any atom
is concentrated in its nucleus.
The nucleus is surrounded by an electron cloud
which produces an invisible field of force,
and acts like a shock absorber.
The configuration of the electron cloud
determines the nature of an element.
In the ordinary course of things here on earth,
the nuclei never touch.
We have a sensation of touching,
but that's really just our invisible force fields
overlapping and repelling each other.
The nucleus is very small
compared to the rest of the atom.
If an atom were the size of this cathedral,
its nucleus would be the size of that mote of dust.
An atom is mostly empty space.
To understand the nature of matter,
we have to go deeper still,
to a place 100,000 times smaller than the atom:
Its nucleus.
The simplest and most plentiful atom
in the cosmos is hydrogen.
Its nucleus is a single proton,
which makes hydrogen element number one.
The clouds that surround it
are the realms where the atom's lone electron
is permitted to roam.
What happens when you have a nucleus with two protons?
Protons repel each other.
In order to hold them together in a nucleus,
you need other particles called neutrons.
Their job is to keep the protons
from getting out of line.
They overwhelm the protons
with their strong attractive nuclear force.
A nucleus with two protons is element number two,
otherwise known as helium.
A nucleus with six protons is element number six,
which is carbon,
the fundamental building block of life.
The nucleus of a gold atom has 79 protons.
They attract 79 electrons
in clouds around it.
The way light interacts with those electrons
is what makes gold glitter.
Every additional proton in the nucleus
requires enough neutrons to bind them together...
Up to a point.
There's an upper limit to the number of neutrons
you can stuff into a nucleus
before it becomes unstable.
I know a place
where the nuclei of different atoms
actually do touch each other.
The sun looks like a solid object,
but it's not.
It's so hot that all its atoms
are always in their gaseous state.
The bonds that join atoms
to make solids and liquids on earth
are not strong enough to withstand
the heat of the boiling sun.
Those arcing streams of incandescent gas
that dwarf the earth
are guided by magnetic lines of force
that emanate from below the surface of the sun.
Why is the sun so hot?
Because its own stupendous gravity
is squeezing its atoms together.
The energy of gravity is being transformed
into the energy of moving atoms.
That's what heat is.
The deeper we go into the sun,
the greater the squeezing
and the higher the temperature.
In the heart of the sun,
the atoms are moving so fast
that when they collide, they fuse.
Their nuclei touch.
The sun is a nuclear fusion reactor,
held together by its own gravity.
It's balanced between the inward pull of gravity
and the outward push of its hot gases.
That balance has lasted billions of years,
providing stability that made possible
the evolution of life on earth.
In the sun's core,
the fusion of hydrogen into helium
releases nuclear energy in the form of photons.
These particles of light
slowly work their way to the surface,
where they're seen as sunlight.
Helium is the ash of the sun's nuclear furnace.
The sun is a medium-sized star.
Its core is only a lukewarm ten million degrees...
hot enough to fuse hydrogen,
but too cold to fuse helium.
There are many stars in the galaxy
that get much hotter,
because they're more massive
and have more gravity.
Such stars fuse helium into heavier elements,
like carbon and oxygen.
In their old age,
they gently diffuse these elements into space.
Other stars, more massive yet,
live fast and die young
in cataclysmic supernova explosions.
In our galaxy, such stars go supernova
about once a century.
These explosions are far hotter than the core of the sun...
hot enough to transform elements like iron
into all the heavier ones
and spew them into space.
The large magellanic cloud
is a neighboring galaxy of our milky way.
It's visible in the skies of the Southern hemisphere.
When a supernova explodes,
its brightness rivals
that of its entire galaxy.
But all that light is only about one percent
of the energy liberated in the explosion.
The rest of the energy is carried off by the most common
and the most mysterious particles in the cosmos.
There are trillions of them passing through you right now,
and yet tracking down even one of them
will take us to one of the strangest places on earth.
Stalking the wild neutrino
is the rarest of sport.
The lengths one must go to track them down
is nothing short of astonishing.
Welcome to Super Kamiokande,
the subterranean Japanese neutrino detection chamber.
We're more than a half mile beneath earth's surface.
You might ask, "well, who in their right mind
would bury an astronomical observatory so far underground?"
Those who hunt the most elusive prey in the cosmos:
The neutrino.
This enormous array of light detectors
surrounding 50,000 tons of distilled water
is a trap designed to catch neutrinos only.
Other particles, such as cosmic rays...
mostly protons and electrons that rain down from space...
cannot get through all that rock above us.
But matter poses no obstacle to a neutrino.
A neutrino could pass through 100 light-years of steel
without even slowing down.
Neutrinos hardly interact with matter at all.
That's why you need so much of it
to catch even one of them.
On those rare occasions when a neutrino
actually does collide with a particle of ordinary matter,
it produces a ghostly, ring-shaped flash of light.
We're lying in wait
for a particle that weighs next to nothing.
Even the miniscule electron
has more than a million times its mass...
There!
When the supernova in the large magellanic cloud
blew its top in 1987,
this is what it would have looked like in here.
Now remember, the large magellanic cloud
is in our Southern hemisphere,
so the neutrinos didn't come through
that half-mile of rock above us,
they had to pass through the thousands of miles
of rock and iron below us to reach this detector.
But the coolest thing was that those neutrinos
hit earth three hours before
the light from the supernova did.
If nothing can travel faster than light,
how could that possibly be?
This is a dead star walking.
It may look normal, but deep within it
something cataclysmic is happening.
This blue super giant star
has already begun to explode inside.
Like rats deserting a sinking ship, the neutrinos
produced in the heart of the exploding star
race outward at near the speed of light,
through overlying mass
in only a few seconds.
But the shock wave of the exploding gas
plods along from the center of the star
at 1/10,000 the speed of light
until it finally reaches
the star's surface,
turning it into supernova 1987a.
It took hours for the explosion
to reach the surface of the star and blow it wide open,
exposing the super hot core.
The neutrinos had an insurmountable head start.
That's why the flash of light arrived on earth
so much later than the shower of neutrinos.
Before anyone had ever snared the wild neutrino,
it existed in the mind of a theoretical physicist.
Just as Charles Darwin knew
there must be an extremely long-nosed creature
flying around somewhere in Madagascar,
a 20th-century physicist named Wolfgang Pauli...
was desperately seeking a particle
to rescue one of the pillars of modern physics,
the law of the conservation of energy.
So why didn't I flinch?
Because the laws of science differ fundamentally
from those of other human endeavors.
In order for an idea to become a scientific law,
it has to unbreakable.
That's why I was willing to bet this face
on the laws of conservation of energy.
Now, if you try this at home,
take care not to give the cannonball a push.
That's adding energy,
and the ball will surely come back and do some damage.
You just have to let it go, like this.
By lifting the ball,
you give it gravitational energy,
which is the potential to fall and accelerate.
The cannonball is going fastest
when it's at the bottom of its arc,
and at that moment,
it's converted all of its gravitational energy
to the energy of motion.
As it swings, the cannonball is constantly exchanging
one of these two kinds of energy for the other,
but the total amount of energy remains constant.
That's an example of the law of conservation of energy.
Once the cannonball is released,
it can never gain more energy than it had to begin with.
It has no way to fly up and break my nose.
The energy accounting books are always strictly balanced.
There's no such thing as cheating.
So in the 20th century,
when physicists first calculated the energy of atoms precisely,
they were startled to discover
an apparent violation of this law.
They found that in some radioactive atoms,
the nucleus can spontaneously eject an electron.
This transforms the atom into a different element.
The physicists were mystified.
The energy of the escaped electron
plus that of the new element
adds up to less than the energy in the original nucleus.
But the law says,
"thou shall not destroy or create energy."
So where did the missing energy go?
In 1930...
Wolfgang Pauli predicted
there must be an undiscovered particle,
one that makes off with the missing energy.
At the time, Pauli lamented
that such a phantom particle might be so minute,
swift and evasive
as to forever defy detection.
But that was a rare failure of his imagination
because science is always searching
for a way to go deeper still.
A generation later,
Pauli's neutrinos were actually detected for the first time
in radiation from a nuclear reactor.
And we've been finding them, with difficulty, ever since.
There are scientists today
who are trying to find a way to ride those neutrinos
all the way back to the beginning of time.
We'll go as far as they have gone
to come up against the wall of forever.
The wall of forever is nothing new.
Our ancestors came up against it
almost as soon as they first started imagining it.
A million dawns ago, in the 13th century bc,
the Egyptian this temple at Abu Simbel
to honor the Pharaoh Ramses II,
depicted here in four colossal statues.
Reigning even above even this mighty king
is the falcon-headed Ra-Harakhti,
God of the sun.
The temple was designed
so that the light from the rising sun
could only enter the sanctuary on two days every year.
As the rays enter the temple,
they burnish the statues of the gods
with their golden light
before penetrating the sanctuary.
Even then, one God remains in shadow.
Ptah, lord of creation,
as if the origin of the universe
must forever be concealed.
Feel the sun on your face.
The energy that warms you
began its journey some ten million years ago
in the heart of the sun.
Unlike neutrinos,
the photons needed
that long to work their way out from the core to the surface.
Why?
Because they were colliding billions of times per second
with the sun's atoms, every collision
sending them off in a random direction.
But once they finally reached the surface,
they were free
to dash nonstop, at the speed of light,
in a mere eight minutes and 20 seconds
from the sun to you.
Ten-million-year-old light on your face.
What was happening
when that light left the heart of the sun?
The cosmic calendar compresses
the entire 13.8 billion year history
of the universe into a single year.
Every month represents about a billion years.
Every day, about 40 million years.
The universe is so old that, on the cosmic calendar,
ten million years ago only takes us back as far as...
6:00 P.M. on the last evening
of the last day of the year.
And what about us?
Humans had yet to evolve.
Ten million years ago,
our ancestors were anthropoid apes,
swinging through the trees of Africa.
To us, ten million years seems like a long time,
but it's only the length of an afternoon
on the timescale of the cosmos.
The sun began fusing hydrogen
4,500 million years ago...
August 31 on the cosmic calendar.
Our milky way galaxy
is about 10,000 million years old.
The first galaxies formed about a few billion years earlier.
And something keeps me from going any further back in time.
What is this?
It's the nature of light and time.
Because light travels at a finite speed,
to look across space
is to look back in time.
So the farther we see,
the older the light.
This is as far back in the history of the cosmos
as we can see with light.
It's a baby picture of universe,
when it was only 380,000 years old.
That's 15 minutes into January 1st
on the cosmic calendar.
If we look as far as we can see in any direction
using microwave telescopes,
this is what we see,
the glow left over from the Big Bang.
Imagine that all the matter and energy
of the observable universe
was concentrated into something
no larger than this.
That's the size of the universe
when it was a trillionth of a trillionth
of a trillionth of a second old.
All the matter and energy of the hundred billion galaxies
now splayed out across the billions of light-years
were once pent up
in something the size of a marble.
Can you imagine how tightly packed
that marble must have been?
Far too dense for any kind of light to move through it,
but no obstacle for the likes of neutrinos.
The big bang must have produced stupendous numbers of neutrinos,
which flew unhindered
through that inconceivable crush of matter.
The very thing that makes them almost impossible to detect
is what allows neutrinos to sail through the curtain
that conceals the beginning of time.
Where are they now?
They are here, they're there,
everywhere throughout the universe.
Neutrinos from creation are within you.
From a marble...
To the cosmos.
This is the road that Thales and Democritus put us on
some 2,500 years ago...
a road of endless searching,
a relentless, systematic hunt for new worlds
and an ever-deepening understanding of nature.
Who among you will pick up that torch
and take us down that next stretch of road?