All language subtitles for S43E19 - Treasures of the Earth - Metals.en

Gemstones, precious metals,
and power...

...the building blocks
of civilization.

But how are they created?

Our Earth is a master chef.

She knows how to cook.

It's not easy
to make an element.

You need temperatures
that are extreme.

In this episode, how do metals
shape our world?

I love steel.

It's actually the backbone
of our society.

And will these gifts be used

to build the tools of tomorrow?

So I think of the Terminator.

He can change shape
and then self-heal.

And actually, our material
does all those things.

We're going to launch
this incredible telescope,

and we're going to send it
a million miles

into space from the earth
to actually unlock

the secrets of the universe.

And it will all rely
on two ounces of gold.

"The Power of Metals."

Right now on
NOVA.

Major funding for
NOVA
is provided by the following...

By the light
of an ancient campfire,

a discovery was made that
changed the course of history.

We don't know exactly
how it happened,

but I sometimes wonder whether
it wasn't a complete accident.

Whether by chance
or through sheer determination,

once humankind learned how
to harness the power of fire,

we left the Stone Age behind,

forging our way
into the modern world

with copper, bronze,

iron, and steel-- the metals.

A world without metals
would not have tall buildings,

it would not have fast vehicles,

you wouldn't be able
to have electricity.

Really, our entire modern world

is built on the backbone
of metals.

Our journey begins with a metal

that's transformed life on Earth
through its beauty.

A metal that fortune hunters
were willing to die for,

and not just in the movies.

There's nothing more beautiful
than gold, nothing in the world.

You just feel it
when you see it.

Ancient people valued gold

before the concept of currency
or money even existed.

It's something that people
intrinsically knew had worth.

Gold is absolutely magical.

Gold is the most fantastic
jewelry metal to work with.

It's so soft, it's so flexible,
it's like butter.

Working with gold ruins you
for any other metal.

You're never the same again.

Jeanette, a master jeweler,

is making a pair
of gold earrings.

I specialize in ancient
jewelry-making techniques.

The kind of expertise
and skill that were used

for making jewelry
really made it an art form.

I make my own wire and sheet...

...and practice techniques
like granulation.

The technique I'm going to use
for the hanging fringe

actually originates from Troy
from about 2450 BC.

Gold is unique
among the elements.

Gold is extremely resistant
to oxidation, to rusting.

If you make an object
out of gold,

it's the one thing that you have
that doesn't degrade.

So to ancient people,

that must have been very,
very appealing.

The color of gold draws you in.

Ancient people saw it

and knew that it was something
incredibly special.

Gold is not only beautiful,
it's rare.

In fact,
if you take all the gold

that's been mined to date,
it's estimated it would fill

about a third
of the Washington Monument.

But to understand

what makes this rare
and noble metal last forever,

we need to take a closer look--
a much, much closer look.

Using one of the most powerful

electron microscopes
in the world,

David Muller studies
the elements.

Probably the most fun in the lab
is when we put something in

and the picture comes up
and you look and you go,

Wow, that's not
what I expected.

That's interesting.

And that's usually the start
of a new scientific discovery.

Today, Muller is observing

the curious behavior of gold,
atom by atom.

All elements are made of atoms.

Inside is a nucleus filled
with positively charged protons

along with neutrons that have
no charge at all.

Swirling around the nucleus
in a cloud

are negatively charged
electrons.

It's the relationship between
gold's nucleus and its electrons

that holds the key
to its resilience.

We're now at 7,000 times
magnification,

seven times higher than
the highest magnification

of an optical microscope.

And if we zoom up some more,

we start to see
there's this nice pattern.

These are little islands
of gold.

And if we zoom up a little bit
further on them,

we'll start to see little bright
spots all by themselves.

Those are individual atoms.

Every one of these clusters

contains thousands
of bright dots,

thousands of gold atoms.

Little gold atoms

form small clusters,

and they keep rearranging
and changing.

They're not static,
they're not stable.

They're dynamic--
they're moving all the time.

Gold atoms love to be together.

But when it comes to bonding
with other elements,

they're downright antisocial.

When atoms bond,

they do it through
their outermost electrons

by sharing or swapping them.

But gold's 79 protons
fight the urge

because they have
an immense positive charge.

That positive charge
pulls in the electrons.

The real consequence is that
the outermost electrons in gold

are much less available
for doing chemistry

than we might otherwise expect.

That's why gold doesn't bond
with elements like oxygen

that cause metals
to tarnish and rust.

The reason that
we're able to appreciate

the gold masterpieces
from 2400 BC

is because gold lasts forever.

It's just as beautiful today

as it was
thousands of years ago.

You can't say that

about anything else
that you could work in.

How did such
a unique metal form?

It's not easy
to make an element.

You need temperatures
that are extreme,

and we're talking
millions of degrees.

The heavier the element,

the hotter the temperatures
required to make it.

And you find those temperatures
in the cores of stars

that are ten times the mass
of the sun or greater.

It's within the intense heat
and pressure

of these massive cores

that the elements
progressively take shape,

bonding together
in a process called fusion.

You can sort of imagine

building up all the elements
that exist in the universe

by taking a pile of neutrons
and protons and electrons

and putting them together

to build up bigger and bigger
and bigger atoms.

When the number of protons
and electrons hit 26,

forming iron, the process stops.

Once iron's made in the core,
that's it.

There's no more available energy
for fusion.

Those massive stars will explode
and go what's called supernova.

One of the key
open questions, though, was

what about the heavier elements?

What about gold and platinum
and uranium?

Where do those come from?

At the end of supernova
explosions,

new kinds of stars are formed
called neutron stars.

They often come in pairs--
binary stars.

They're extremely dense

and compact and heavy.

It weighs about one-and-a-half
times the mass of our sun,

but it's the size of a city like
New York or London or Boston.

And they incorporate
a lot of neutrons,

which is why they're called
neutron stars.

Some scientists theorize that
elements heavier than iron

were created in the collision
of two neutron stars.

What happens when they collide?

Fusion on a massive scale.

The elements were spread
throughout the cosmos,

so they were in the mix
when our solar system formed

4.5 billion years ago.

And later, more were delivered
to Earth

by comets and asteroids.

Most of the elements
on the periodic table

came to us from space.

We classify them in groups

defined by their
characteristics.

The largest group is the metals,

and one of the most beautiful
by far is gold.

Now this ancient treasure
is going back to space

onboard the most advanced
telescope ever built.

It's the next big
space telescope.

We like to call it Hubble 2.0.

Hubble 2.0 is the James Webb
Space Telescope.

In 2018, we're going to launch
this incredible telescope,

the largest space telescope
mankind has ever built,

and we're going to send it
a million miles into space

to stare at the earliest part
of the universe,

and it will all rely
on two ounces of gold.

The ultra-thin layers of gold

that coat the telescope's
mirrors

give it the power to detect
galaxies light years away.

Hubble has sort of found

the edge of the visible
universe,

but we know there's
a whole universe beyond that

at wavelengths called
infrared wavelengths.

And that's where gold
comes into the picture.

Infrared light

is invisible to our eyes,

but we can detect it as heat.

And that's why this
thermal infrared camera

will pick it up.

So this is my hand
as viewed by the camera,

and it's about 97 degrees
Fahrenheit.

Now let's look at my hand

reflected in this ordinary
silver-coated mirror.

It says that my hand is
84 degrees Fahrenheit,

which is a lot less than 97,

and that's because
the silver-coated mirror

is not a perfect reflector
of infrared light.

But if we try this
gold-coated mirror...

Now, when I pass
my hand's reflection

over the gold,

it says that my hand is
97 degrees Fahrenheit.

And so what this shows
is that gold

is an almost perfect reflector
of infrared light,

and that's why we coat
all of the mirrors

of the James Webb telescope
in gold--

so that it has
an almost perfect view

of the infrared
invisible universe.

Gold is that ancient treasure

that we've lusted over
over mankind's history,

and here we are
in the 21st century using this

to actually unlock
the secrets of the universe

and perhaps the origins
of where we came from.

What a wonderful historical
transformation.

Historically, this glittering
treasure of the earth

could be found in riverbeds
and streams.

But in order to leave
the Stone Age behind,

we needed another metal,

one strong enough
to shape into tools.

And we found it
in the flames of a fire.

Copper, atomic number 29--

29 electrons, 29 protons,
and 35 neutrons--

is embedded in a mineral
called malachite.

Malachite has this incredible
color, doesn't it?

It's like aWizard of Oz
Emerald City green.

Malachite has been
really important

throughout the history
of our civilization.

This is probably the first
mineral that humans used

to actually extract
copper metal.

Just imagine the following.

Someone comes home
with a beautiful green rock--

malachite.

They decide to grind it
into a powder

and throw it into a campfire.

A magical process occurs.

Nature puts on a light show

as the edges of the flames
turn emerald green.

The flame suddenly becomes
greenish.

You get these incredible colors.

You have no idea
where they come from,

but it certainly provides
entertainment.

And at the same time,

that beautiful green rock
slowly turns black.

The beautiful green malachite
has burnt away.

What's left behind is copper

combined with oxygen
from the air-- copper oxide.

If you left it in the fire
overnight to burn,

then the transformation
would have gone even further.

But in order to free copper
from oxygen

requires another ingredient,
carbon,

which is conveniently provided
by charcoal--

the residue of burning wood.

I want to recreate that for you.

Sella drops a disk
of copper oxide

into a crucible of charcoal

and heats it up
in a modern day fireplace:

the microwave.

What heat really means is
the molecules

and atoms begin to move
much, much faster.

Now it's possible
for the carbon

to actually strip away
the oxygen,

disappearing off invisibly
into the air as carbon dioxide.

But the next morning, the person
who's cleaning up the fireplace,

almost certainly a woman,

would've found tiny
little shiny nodules

lying amongst the ash.

That would've been metal.

This is a magical transformation

that would suddenly have
given you a material

that you could shape,
that you could reuse,

that you could make tools with.

This was power indeed.

This was a birth
of a whole new technology.

This was copper.

Once our ancestors discovered
how to free metal from stone--

the art of smelting--

they had a material they could
shape into bowls and tools.

But they also discovered it has
another surprising quality.

An ancient Egyptian
medical text

dating back to 1600 BC

reveals copper was used as
a disinfectant to clean wounds.

It was also used to make
surgical tools.

As late as the 19th century,

during a cholera epidemic
in Paris,

copper workers seemed to be
immune to the disease.

But by the 1940s,

with the development
of antibiotics,

people lost interest in copper,
its medicinal powers forgotten.

Until now.

At the University
of Southampton,

Bill Keevil has set out to prove

copper can help solve
a dangerous problem:

hospital-borne infections.

If a jumbo jet full of people
crashed each day

and everyone died,
would you fly?

Probably not.

That's how many people die
in America each day

from hospital-acquired
infection.

Hospitals are a breeding ground
for dangerous superbugs.

Just about any surface you touch
is a hot zone.

We know superbugs are perfectly
happy to survive

for many weeks
on a dry touch surface

such as stainless steel
or plastics.

So we need something that works

24 hours a day,
seven days a week.

Could copper be an answer?

Keevil puts it to the test.

He takes a piece of copper

and a metal commonly used
in hospitals, stainless steel,

and coats them
with the superbug MRSA,

along with a green
fluorescent dye.

Next, they place it
in a microscope.

Please start your clocks,

and we will follow
this experiment

over the next five minutes.

At first, the bacteria

on the copper
and stainless steel

glows bright green.

But within minutes,

the copper in the screen
on the right turns black.

This is what they looked like
and this is after five minutes.

So you can see they're all dead.

How does copper do it?

Scientists suspect
it has something to do

with the membrane of a superbug,
which has an electrical charge.

When it meets up with copper,
a kind of short circuit occurs.

The copper penetrates
the membrane,

leaving it with gaping,
oozing holes.

The copper invades the superbug,
destroying its DNA.

If there's no DNA,
there's no growth,

and, in fact,
there's no chance of mutation,

and, therefore,
you can't get resistance.

Copper's ability to kill germs

could one day save
millions of lives.

But it's already revolutionized
the way we live,

because copper has another
extraordinary ability:

it conducts the electricity
that powers the planet.

Metals are extremely
unusual materials.

They can conduct electricity
extremely well.

And when we think
about conducting electricity,

what that means is that

there are electrons
within the material

which are able to move.

Sometimes this is described as
a sea of electrons.

You can kind of picture these
individual atom cores

and then this sea of electrons
all around them.

Metal atoms are arranged
in orderly rows and columns.

In between those columns
are electrons

that are able to move around.

When we apply a voltage
with a battery,

we can start to draw electrons

so that they all move
collectively in one direction.

With a voltage applied,

electrons hop
from one atom to the next.

That's what gives us

the electric currents
that are so useful.

While all metals
can conduct electricity,

copper is one of the best.

And it's abundant.

The worldwide supply is
about six trillion pounds.

But the qualities
that make copper

the metal of choice
to wire the planet

also limit its usefulness.

That sea of electrons
not only conducts electricity;

it creates flexible bonds
between the atoms.

The atom cores

can move through this
sea of electrons

in a relatively easy way,

and that's what makes metals
malleable.

But a metal like copper,
which is malleable enough

to be stretched into thin,
flexible cable,

does not a dagger make.

Copper is actually too soft.

A blade made of copper
loses its edge within moments.

And yet, by combining it

with other rocks
in the fireplace made of tin,

you could make a material

which was stronger, harder,
and stiffer.

That was bronze.

Around 2500 BC,

humankind took the art
of smelting one step further

by mixing metals
to create an alloy.

When you look at copper,
it's pretty boring--

every single atom
looks the same.

But when you look at bronze,

there are two different types
of atoms.

There's copper and there's tin.

Adding tin to copper

changes the properties
of the metal.

The larger tin atoms

restrict the movement
of the copper atoms.

It makes it more difficult
for the atoms

to move past one another
to change shape.

Saying that it's more difficult
to move them around

is equivalent to saying that
the metal is stronger.

Bronze would've provided useful
implements for agriculture,

but more importantly,
it would've provided you

with weapons
to establish your dominance.

And dominance, of course,
means control,

and control means power.

The movies paint a vivid picture

of how bronze transformed
the nature of warfare.

It's the bronze age,
so without bronze,

you don't stand a chance
in battle.

Bronze is like no other material

people would have handled
before.

With it, you can make
harder weapons,

you can make sharper blades,

and you can make them
consistently.

You can cast them in mold

and make them always
of equal quality.

With bronze, you can,
for the first time, really,

equip hundreds,
thousands of warriors

with the same types of weapons,

all of which will perform
and be equally lethal.

So it probably meant
a revolution in warfare.

But not all swords
are created equal.

Back in 1965,
a group of archeologists

discovered more than 50
ancient tombs

in the Hubei province of China.

During the excavation,

they unearthed something
extraordinary.

Jigao Hu was one of the first
people to lay eyes on it.

Hu, an expert in the
preservation of ancient relics,

vividly remembers seeing
a most unusual sword.

The sword had
a golden sheen to it

and had a decent weight to it.

It had the shine
of fresh copper.

There was no rust at all.

Although it had been buried
for more than 2,400 years,

the sword was perfectly
preserved.

Hu found eight characters

written in ancient Chinese
script on the base of the blade.

They identified
the sword's owner:

Goujian, the king of Yue,

a famous ruler
in the 5th century BC.

Everyone came to see the sword,

ecstatic because there were
characters on it.

One young man was
particularly excited,

and he tried to reach for it
and he bumped into me.

I leaped forward a little
and must've touched the sword,

and the sword made a cut

about two to three centimeters
on my hand.

There were droplets of blood
coming from my wound.

It wasn't a deep cut,
but a cut anyhow,

like a shaving razor.

The sword was that sharp.

Later, they tested the sword.

It could cut through
20 sheets of paper.

It was so beautifully crafted,
I was astounded.

The Goujian sword
is well preserved

because of its burial condition.

It is dry,
and no water leaked inside.

Thus, it did not rust.

But its longevity
may also be due

to the extraordinary
craftsmanship

with which it was made.

The smelting technology
from ancient times

has been lost.

But recently, there are people
who start to imitate the styles.

However, they can't manage
to replicate its sharpness.

The sophistication cannot
match up to ancient times.

But bronze has another
resounding quality.

It's the perfect metal
to forge a bell.

In South Korea,
master craftsman Song Chang-Il

is making a ten-ton bell
for a Buddhist temple.

After decades of experience,

combined with an artist's
instincts,

he knows exactly what it takes

to make a bell
with the perfect ring.

First, ten tons
of copper and tin

are heated
to 1,150 degrees Celsius.

When the time is right,

Chang-Il pours his concoction
into a massive clay mold.

The metal is so hot,

it takes two-and-a-half days
for the bronze to cool.

Finally, the mold
is carefully removed

and the bell is tested
for the first time.

That sound that we hear

is really telling us
about the stiffness

and the resilience
of the material.

So when we hear
the ringing sound of a bell,

the entire material
kind of swings.

It becomes elastic

and can then come back
and go forward

and back and forward and back.

Over thousands of years,

through trial and error,
craftsmen like Chang-Il

discovered that the perfect ring
could only be achieved

with the perfect recipe:

a balance between tin
and copper.

But around 1200 BC,
as the use of bronze spread,

and with supplies of tin scarce,

once again,
the flames of a fire

brought us a powerful metal.

Iron.

Atomic number 26--

26 electrons, 26 protons,
and 30 neutrons.

Freeing iron from stone

meant taking the technology
of smelting

one giant step further.

Charcoal burns at
about 1,000 degrees Celsius,

but to smelt iron, the flames
need to be a lot hotter.

a technology that
could literally fan the flames--

a furnace called a bloomery.

This ancient furnace was built
with heat-resistant walls

made of earth, clay, or stone.

At the base,
pipes allowed air to enter

through an elaborate system
of bellows.

The air was pumped manually
by hand or by foot.

Anyone who's been camping
and has made a little campfire

knows that if you lean down
and you blow into the embers,

what they do is they glow
much more brightly.

Because you're introducing
oxygen

and you're raising
its concentration,

you're making it more available.

A fire needs oxygen to burn,

and the more oxygen,
the hotter the flames.

The reaction of oxygen
with the charcoal,

which makes carbon dioxide,

is one which generates
an increase in temperature.

You get a release of heat.

Oxygen made the fire hot enough
to separate iron from stone,

and once again, metal
transformed the way we live,

from tools to weapons.

In time,
the bloomery was replaced

with the more powerful
blast furnace.

And by the 20th century,
iron was everywhere.

The Industrial Revolution

changed nearly every aspect
of life on earth.

But there was a catch.

In the process of smelting iron,

impurities called slag
are left behind.

Slag weakens metal.

Over hundreds of years,
craftsmen discovered that

if iron is hammered and reheated
over and over again,

it gets purer and stronger.

Over time, bit by bit,

they discovered
how to get more and more

of what they wanted
in terms of properties.

But they certainly didn't have
any understanding

at anything even remotely
like the atomic level

of what was going on.

But now we understand that
at the atomic level,

an extraordinary transformation
was taking place.

Iron was turning into one
of the strongest alloys

Earth-- steel.

While hammering
drove out the slag,

the charco in the fire

provided an essential
carbon.

The combination of iron
and carbon to make steel

is almost a unique combination
in the world,

and key to it is that

the iron atom
and the carbon atom

are very different sizes.

When you add a little bit
of carbon to iron,

it tends to hide
in the little gaps

in between the large iron atoms.

The way tin transforms copper
into bronze,

carbon turns iron into steel.

And this is one of the amazing
things about steel.

Just using more or less
just these two elements,

iron and carbon, you can create
lots of different properties

that can be useful
for different applications.

To demonstrate the difference
between iron and steel,

Vinci got access to a piece

of one of the most famous
iron towers ever built.

This is our piece
of the Eiffel Tower.

Discarded after a repair.

I never thought in my life

I would be holding a piece
of the Eiffel Tower.

I mean, I've been up the Eiffel
Tower a couple of times.

The Eiffel Tower is made
of wrought iron,

which has less carbon
than steel.

When the Eiffel Tower was built,

wrought iron construction
was really at its peak.

It's an amazing structure

using an amazing material,
especially for its day.

How does the strength
of the wrought iron

in the Eiffel Tower hold up
against steel?

Rick Vinci and Helen Chan are
about to find out.

Not only do we get to hold
a piece of the Eiffel Tower,

we also get to cut it up
and bend it

and maybe even break it.

They conduct a bends test

to determine how much force
can be applied

to the wrought iron
before it bends.

Here we go.

It not only bends; it breaks.

Wow, it broke.

Okay.
This is actually cracked.

When they test the steel,

there are similarities
and differences.

Well, it actually seems
as if the two samples

behave pretty much
the same.

The load that it took to bend it
was comparable.

Okay, so I see
two differences right away.

First of all,
the wrought iron bar cracked

and the modern steel didn't.

But I see another really
important difference,

which is the modern steel bar

is only half the thickness
of the Eiffel Tower bar,

despite the fact that it carried
exactly the same load.

So all that means is if
you are using a modern steel,

for the same amount of material,

you can support
four times the load.

Wow.

All right.

In fact, around the time
the Eiffel Tower was built,

steel was already on its way
to becoming the metal of choice

for building high.

Chicago's towering ten-story
Home Insurance Building,

the world's first skyscraper,
had a steel frame.

Steel had a huge influence

on the development
of this country

as an dustrial nation.

And today, steel can do things
that are hard to imagine.

Nothing demonstrates that

quite like the Beijing
National Stadium,

nicknamed the Bird's Nest,

42,000 tons packed into a design
that seems to defy logic.

Engineer Michael Kwok
was a project manager

for the design and construction
of the Bird's Nest.

It's more like a jigsaw puzzle,

you just try to figure out
how this was put together.

It is very unlike

pretty much any other structure
that's been built.

If you want to make
a strong structure,

there are certain classic shapes
that work very, very well,

and the truss is a classic one.

If you look at bridges
all over the place,

they have these
triangular elements,

these truss elements that are
very, very strong.

The geometry of a triangle

makes it an inherently
stable shape.

Put several of them in a row

and they distribute the weight
of a structure

to its load-bearing beams.

But the Bird's Nest
looks nothing like that.

But looks can be deceiving.

24 sets of columns
connect to a series of trusses

that support the roof.

All this is hidden
behind a maze of steel.

You can't make that out of just
any run-of-the-mill steel.

You need a particularly
high-strength and tough steel.

The stadium is made
of two kinds of steel.

The recipe for the trusses
provides extra strength.

But to create the beauty
of its winding exterior

required steel
with more flexibility.

For a massive steel structure
like this,

the combination of flexibility
and strength is critical...

especially in an earthquake-
prone region like Beijing.

The bowl of the stadium,
made primarily of concrete,

does not have the elasticity
of steel.

So the engineers and architects
came up with an innovative idea:

separate concrete from steel;

make them work as two
independent structures.

The extraordinary properties
inherent in steel

make it possible for engineers
like Michael Kwok

to build structures like this
that capture the imagination.

Today, by mixing different types
of steel for different purposes,

engineers have taken
the art of steelmaking

to new heights-- literally.

The tallest bridge in the world,
the Millau Viaduct in France,

is made of steel that contains
an element that's quite rare:

niobium.

It is a soft,
whitish gray metal,

and if you add it to steel,

you get a stronger,
lighter material.

When you think about a solid
piece of metal,

it just looks like
it's all the same.

But in fact,
if you really zoom in,

that chunk of metal
is typically made up

of lots of little individual
metal grains.

And it turns out that if you can
make those grains really tiny,

then it makes it
much more difficult

for the atoms to move past
one another to change shape.

So by making the grains tiny,
you make the metal stronger.

Now, niobium prevents
the growth of these grains

very effectively, and then
you can get incredible strength

that comes from having this
very tiny grain size.

Different kinds of steel
can have other additives,

like nickel, chromium,
or manganese.

But there's one
rather bizarre recipe

that could help solve one
of the world's biggest problems.

We've been seeing landfills
as a huge environmental burden,

and of course it appears
that way on the surface

because we don't know
what else to do with it.

But if we can reform
end-of-life materials

into completely different
products,

then suddenly, landfills
shouldn't be seen as a burden;

they should actually be seen
as this amazing possibility.

It's a treasure.

Veena Sahajwalla
has developed a way

to recycle the stuff
nobody wants-- trash--

and turn it into steel.

The most basic steel

is nothing but an alloy
of iron and carbon.

Well, guess what?

We can find carbon in plastics.

The first step:

take some plastic
like this broken headlight.

Look at what I got you!

Cut off a piece and melt it down

to a small pellet
chock full of carbon.

Top it off with a lump
of pure iron.

Place the combo
back in the furnace

and heat it up.

Now watch the alchemy unfold

as the carbon in plastic
bonds with iron.

What's exciting here is that

we're actually seeing
this high-temperature reaction

taking place
right in front of our very eyes.

We've got this liquid metal.

We're now looking
at how this is interacting

with this source of carbon,
which of course is the plastic

that came from a waste
out of a car.

Carbon from that plastic

is actually able to dissolve
into liquid metal.

So this is what's come out
of the furnace.

We've dissolved the carbon
from the plastic

into liquid iron.

And of course,
what we have here is steel.

After a decade of research,

Veena's "green steel" is slowly
making its way out of the lab.

Partnering with the manufacturer
One Steel,

they have already recycled
over two million tires.

Today's tires are made
of a synthetic rubber,

produced from oil
rich in carbon--

the perfect ingredient
for green steel.

And when it comes
to greenhouse gases,

Veena's steel requires
less coal to cook,

and that reduces
its carbon footprint.

As the saying goes, you know,

one person's trash is
somebody else's treasure.

Guess what?

This could become
our society's treasure.

I love steel because
it has really given us

the structures that have
changed this world around us.

Steel has given us the power
to build high and strong.

But as wonderful and versatile
as it is, steel has limitations.

One of the drawbacks to steel
is that it is relatively heavy.

Iron is fairly dense,
and for its strength,

you have to make
massive structures.

And that's fine
if you're building a bridge,

but it's not fine
if you're building something

that needs to move.

And that's where
another extraordinary metal

comes into the picture.

Atomic number 13, aluminum
has just 13 electrons,

13 protons, and 14 neutrons.

In comparison
with a heavier metal like iron,

which has twice the number

of protons, electrons,
and neutrons,

the aluminum atom
is incredibly light.

Aluminum has
an ethereal lightness

that no one could believe.

And yet, it also has some
of the properties like steel

that allow you
to modify its strength

and its other characteristics
to optimize it.

Aluminum has completely

transformed our world,

from the trivial tent pegs
of our tents

to the frames of our aircraft,

where it really makes
a difference.

If we had to build our airplanes
out of steel,

they would have to have
fuel tanks

five or six times bigger
than they do now

and would carry a third
of the passengers.

Today's aluminum is really
fabulous stuff.

If you can live
with a little bit less strength

in exchange
for a lot less weight,

then aluminum is
an excellent choice.

But as we look to the future,

another way to move forward
is to ask ourselves

if what we have been doing
with metals for all these years

is the only thing we can do.

Imagine a material that is not
just light, not just strong,

but flexible enough
to change its shape.

So I think of the Terminator
with this project,

which is super fun,

and I don't think I've seen
the Terminator

since I was young,

but one of the images

that really stuck with me
is the T-1000,

you know, the all-metal guy,
right?

He can change shape
and then self-heals.

Actually, our material
does all those things.

This is metal foam,

a combination
of metal and rubber.

Heat it up and it morphs
into another shape.

And when it's done,
it becomes a solid again.

The idea of this metal foam
is that we can have sothing

that changes its shape
dramatically,

but then after it changes
its shape,

have a lot of strength.

What's the recipe
for making metal foam?

First, take a dash
of Himalayan salt,

add a little dragon skin--

also known as
uncured silicon.

Mix it up,

pour the mixture into a mold,

and let it cure.

Remove the concoction
from the mold

and place it
in an ultrasonic cleaner.

This dissolves away
the Himalayan salt.

What's left behind is a porous,
sponge-like material

riddled with tiny crevices.

Next, submerge the foam
into a bath

of molten Field's metal.

Field's metal is

a low-melting-temperature alloy
of indium, tin, and bismuth.

So at 60 degrees Celsius,
it is a molten liquid.

Below 60 degrees Celsius,
it's a frozen solid.

The metal-covered foam
is sealed in a vacuum chamber,

where the molten metal
seeps into those tiny crevices

that were left behind
by the salt.

Air trapped in the foam
is pushed out

and rises to the surface.

The sample is then removed
from the vacuum chamber

and cooled down.

Once it's at room temperature,
it hardens again.

Shepherd hopes one day,

metal foam will be able
to make like a bird.

One of the problems I'm trying
to solve with this material

is inspired by a puffin.

A puffin can fly,

but then it can dive underwater
to catch fish,

so it has to sweep
its wings back

in order to not have
its wings torn off.

So in an artificial version
of the puffin,

we would want a vehicle

that could turn from a plane
to an underwater glider.

This idea is quite imaginative
and a far-reaching goal,

but we are currently working
on a wing

that we will coat
in a skin of this metal foam,

and we're going to try it out
on a radio-controlled airplane

in the next year.

But metal foam could find
another home-- in space.

If you think about kind of
a limited resources setup,

certainly if you're, like,
in outer space

and you have a limited number
of things

you can bring with you,

and maybe you don't know exactly
what tools you need,

but here you have this material,

and you can really
change its shape

and then lock it in
to whatever you need.

So you can take it one day
and use it as a wrench,

and take it the next day
and use it as a hammer.

One day, metal foam

could make its way
into your toolbox.

Eventually, we believe

this composite could be used
for reconfigurable tools.

At thipoint, we think there
are some flaws in the structure

that may cause it to fracture,

but these are
engineering problems

that we think are very solvable.

While some researchers

are exploring new ways
to combine materials,

others, like David Muller,

are fascinated with a newly
discovered treasure,

the strongest material
ever found:

graphene.

Made of pure carbon, graphene
behaves a lot like a metal,

but it's about 200 times
stronger than steel

and harder than diamonds,

even though it's just
one atom thick.

Graphene has incredible
strength.

Combined with incredible
strength,

it has incredible flexibility.

How strong is graphene?

Some researchers estimate

it would take an elephant
balanced on a pencil

to break through
a sheet of graphene

the thickness of Saran wrap.

Where can it be found?

You have to bake it.

First, take a piece of copper
and place it in an oven.

Fill it with a material
that contains carbon.

David Muller uses methane,

a gas that's a combination
of carbon and hydrogen.

We knock all the hydrogen off
by heating it up very hot,

so that gets turned
into just carbon atoms

that are floating around
in a vapor.

Those carbon atoms fall down
and bombard a flat surface.

So the way you think of this is

my copper surface is just like
a cold window on a cold day,

and then little bits of moisture
are in the air

and they start to condense
onto my cold window,

and instead of growing
little ice crystals

that decorate all the way
across my window,

I'm going to grow little
crystals of carbon

that are going to decorate
my copper surface.

And eventually,
these little crystals

are going to grow bigger
and bigger and bigger

until eventually,
they touch each other,

and then I have one uniform
continuous sheet of carbon,

and that will be the graphene.

What makes this incredibly thin
layer of carbon so strong?

It all comes down
to the arrangement of its atoms.

When six carbon atoms bond,
they form a hexagon.

And as more and more
carbon atoms join the group,

more hexagons take shape.

So you can imagine

that if another carbon atom
comes down

and lands over here,
right in the middle,

it's got nothing to stick to.

It's going to keep rolling
around,

but then it gets to the edge
of the sheet of the graphene

and says, "Wait a minute,
there's a dangling bond.

I want to attach to that."

And then it'll continue
to grow out,

and that's why the sheet gets
bigger and bigger and bigger.

Once the baking is done,

the graphene-coated copper
is taken out of the oven

and placed in a solution that
slowly etches the metal away.

What's left is a small sheet
of graphene.

Exactly what can you do
with a single layer of graphene

that's so thin,
it's barely visible?

So we could imagine graphene
would be very valuable

for things on the nanoscale.

Because it's both tiny
and strong,

it could fit inside a cell
for medical applications

or be placed in dust
for environmental monitoring.

But graphene might also have
applications on the megascale.

If you could build cables,
for instance,

for holding up
suspension bridges.

If you could get
to that size scale,

then that would open up

incredible new
engineering opportunities

for creative people
to make structures

that we really can only
dream of today.

Is graphene the next big thing?

No one can predict
if new materials

like metal foam or graphene
will live up to their promise.

But there's no doubt that metals

have revolutionized
life on Earth,

from the beauty of gold
to the smelting of copper

to the creation of bronze
and steel.

And in the future,
materials we can only dream of.

And the astonishing thing
is that the work of engineers,

of metallurgists,
and of chemists every year

brings us new formulations,
new possibilities

that makes things lighter,
stronger, stiffer,

faster than anything
that came before.

Earth's amazing
natural resources.

We use them to build
our civilization.

I love steel because it has
really given us the structures

that have changed this world
around us.

But how will we power
our future?

The magic of the desert,
the sun, the sand,

they produce a lot of energy
and they can power a whole city.

The quest to fuel tomorrow.

"Treasures of the Earth,"
next time on NOVA.

This NOVAprogram is
available on DVD.

To order, visit shopPBS.org,
or call 1-800-play-PBS.

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