Nova (1974–…): Season 48, Episode 2 - Beyond the Elements: Reactions - full transcript

The chemical reactions that transform the world, from explosions to photosynthesis; lock-and-key molecules that put the heat in peppers and make venoms useful to medicine.

Are you wondering how healthy the food you are eating is? Check it -
What's it take to make our
modern world?


That's amazing!

I'm David Pogue.

Join me on a high-speed chase

through the elements...

and beyond.

Oh, my God!

As we smash our way into
the materials,


and reactions...

It's a really cool enzyme

because it makes life on Earth

That make the places we live,

the bodies we live in,

and the stuff we can't seem
to live without.

The only thing between me and
certain death...

is chemistry?

From killer snails...

Just when
you think you've heard of everything,

nature will surprise you.

And exploding glass

to the price a pepper-eating
Pogue pays.

There's got to be some easier
way to learn about molecules.

In this hour, we'll dig into
the surprising ways

different elements
combine together

and blow apart.

Come for the chemistry,

but stay for the bacon

The power of bacon!

"Beyond the Elements:

Right now on "NOVA."

Imagine that you're about
to take your first shot

in a game of pool... the break.

But when the cue ball hits
the other balls...

...they all turn into a rat.

Or imagine you snap a pencil
in two...

and it becomes a flower...
and a fork.

That's how weird and surprising
some chemical reactions are.

You can take something
as dangerous as the element sodium,

which explodes
on contact with water...

combine it with a lethal gas,
the element chlorine,

and end up with something
utterly different:

sodium chloride...

table salt for your fries.

Transformative chemical
reactions are everywhere,

they're going on all the time.

They put the bang in

That's a reaction!

Round 2.

And the "heat" in hot peppers.

What am I doing?

Learning how to harness them

has given us some control over
our world

and maybe even helped
to make us human.

And few folks know more about
chemical reactions...

This is not normal fire.

Than my old friend Theo Gray.

Today, I've come to his
mad scientist lair in Illinois

to find out more about one of
the most powerful weapons

in our reaction arsenal...

Oh ho, ho, ho!


Fire is a chemical reaction,

plain and simple.

It happens to be the
most important chemical reaction

ever, times ten... bar none.

When you think about the
importance of fire

to human beings becoming who we are,

it's kind of the start
of civilization almost,

discovering how to control this
amazing thing... feeds us,

chases away the bears,
it lights up the night.

There's almost nothing you could name

that's more important than fire.

So what is fire, anyway?

You may have learned
this in school.

To make fire,
a kind of combustion,

you need fuel plus heat
plus oxygen.

That formula is simple...

but what's happening isn't.

And what's actually happening
here is kind of subtle.

The wood itself isn’t really burning.

You see the flames?

Yeah... Most of the reaction is happening

up in the air above the wood

because it needs
to mix with air.

Like, there's no air
in the wood.

And what's happening is
the heat of the flames here

are breaking down

and evaporating compounds in the wood,

bringing them up into the air.

Those gases from the wood
are complex molecules

made mostly of hydrogen,
carbon, and oxygen.

When the rising gases enter

the high temperature
area of the flames,

they're joined
by oxygen from the air

in a swirling cauldron
of complicated reactions.

The gases break down,
and their atoms rearrange.

If the gases burn completely,

they'll form water
and carbon dioxide.

More often,
incomplete burning produces

a variety of other molecules.

Importantly for us, the reactions
also release energy...

the light you see
and the heat you feel.

And that, at its heart, is
what happens in chemical reactions...

The breaking and making of bonds

and the shuffling around
of atoms.

You take two different things,
you smash them together,

they rearrange themselves,

and then you get...
something else comes out.

And one of the big-time players
in the game...

Is oxygen.

You ready?

With enough heat it reacts
with just about anything,

as Theo soon shows me
in his barn.

This powerful cutting tool
is called a thermic lance.

It uses pressurized oxygen
fed through a metal rod.

This one's made of iron.

We don't normally think of iron
as something that can burn,

but when lit in the flow
of oxygen,

it does,
generating so much heat...


...that you can cut through
a brick or concrete.

Demolition crews use large
thermic lances

to slice up all sorts of big,
unwieldy things...

from bridges to ships
to machinery.

But does the rod that burns in
the stream of oxygen

need to be metal?

I shudder to ask...

why you've got plates of bacon here.

Well, because bacon is the funniest thing

that you can form into a
tube and shoot oxygen through.

Unfortunately actual American-style bacon

doesn't hold together well enough.

We need the engineering grade.

This is Italian prosciutto.

Theo has already baked
some tubes of prosciutto.

The next step is to wrap them
in yet another piece

to create one large hollow tube,

which he hooks up to his oxygen

Okay, so now, what can we do with this?

The same thing you do
with any sort of thermic lance.

You cut something with it.

Uh, we're going to cut steel...

- because, why not?
- No!

You're going to cut steel
with bacon?

Yes, a steel baking pan.

Wow. You just have to get it hot enough.

The power of bacon!

That's amazing!

Yeah, I mean that's, that’s a
good amount of cutting there.

I've heard of steel-cut oatmeal
for breakfast, but...

Bacon-cut steel?

Gaining control over fire
has had an immeasurable impact

on human civilization.

In fact, the most popular
construction material

in the world has its roots

in one of the oldest pyro

roasting a certain kind of rock.

We know it as concrete.

Modern concrete
is a mixture of aggregate...

materials like sand, gravel,
and crushed stone...

With a binder...
These days, most often cement.

And that's key.

Because people are always
confusing concrete...

and cement.

Cement is the glue,
concrete is the end product.

Cement sidewalks?

No, that's concrete!

Cement trucks?

Uh-uh, they carry concrete!

But cement is
the key ingredient.

And that's why I head to the
Lafarge Holcim Cement Plant,

the largest in the U.S., located
outside St. Louis, Missouri.

We shoot rock every day.

My day with plant manager
John Goetz

begins with a bang.

Fire in the hole!

Is it safe to go down there?

Not quite.

How's that for you?

That's a reaction. That's awesome, huh?

Do it again!

Now that, my friends,
is a lot of limestone.

That's a lot of rock.

Before long, this will be
holding together

America's buildings and sidewalks and...

That's right,

we're going to turn this
limestone into cement.

But what exactly is limestone?

It's mostly calcium carbonate...
A compound that,

as its name says, has two parts.

There's a calcium atom that has
given up two of its electrons,

making it a positively charged

The other part is carbonate,
made up of three oxygen atoms

that are sharing electrons
with a carbon atom.

Sharing electrons is called
covalent bonding.

The two electrons from the
calcium have joined the party,

making the carbonate
a negative ion.

The positive calcium ion and
the negative carbonate ion attract,

forming... surprise...
An ionic bond.

From the quarry,

the limestone rock gets
gradually crushed down,

along with some clay
and other ingredients,

into a fine powder called

"raw meal,"

in preparation
to enter the centerpiece

of this whole operation:

a rotary kiln,
about 22 feet in diameter

and about 100 yards long.

It's a big kiln,
largest in the world.

Kiln, as in, like, an oven?

Correct, gas temperatures
inside the kiln

right here is about 2,000
degrees Fahrenheit.

Just before it enters the kiln,

the powdery raw meal is dropped

through the kiln's hot exhaust

By the time
it reaches the bottom

and the entrance to the kiln,

the heat has transformed
the calcium carbonate

from the limestone into carbon
dioxide gas and calcium oxide,

also known as quicklime.

Normally the kiln rotates at
a speed of about 4 times a minute.

And ordinarily this whole
thing would be turning...

But it was shut down for

Oh man... the mouth of the dragon!

Giving us a chance to see it
from the inside.

So the whole thing is turning.

The whole thing is turning over
four revolutions a minute.

As the material comes down the kiln,

there's a burner pipe with a flame

right here, inside the kiln.

And heating the material
to 2,600 degrees,

the flame temperature is about
3,000 degrees Fahrenheit.

At this point it looks like
dark baby powder?

At this point it looks like lava.

Oh, it does? Yes, it's red hot lava.

As the main ingredient,
calcium oxide,

journeys down the kiln
getting hotter and hotter,

it reacts with the other
ingredients in the raw meal,

creating complex synthetic

By the time the whole mix
reaches the end,

it has a new name...


This stuff is called clinker?

It's clinker.

You couldn't call it
something dignified...

Oh, I didn't name it.
Like calcium carbonate

or sulfur trioxide... clinker?


Coming out of the kiln process,

before it goes into the cooler.

And clinker just refers
to that limestone brew

that's been cooked.Correct.

But it still isn't cement!

In the final stage, they
add a little more limestone

and hydrated calcium sulfate...

a common mineral known
as gypsum.

Conveyer belts seem to
really be a thing around here.

And the whole thing gets ground
back down to a fine powder.

And here it is, at last,

no more grinding, no more ingredients,

this is the finished product.

This is cement. This is cement.

From the virgin
limestone bluffs of Missouri.

There it is.

This Lafarge Holcim plant

produces up to about 4.4 million
tons of cement a year.

But that's just a small

of the 97 million tons produced
in the U.S.,

and the 4.5 billion tons

produced internationally.

Virtually all of it
ends up in concrete

that mixture of cement,
water, and rock

that is second only to water

as the most-consumed resource
on the planet.

That comes at a price though...

a massive carbon footprint.

In 2016, cement production
emitted about 8%

of the global total
of greenhouse gases,

over half of that from
the production of clinker.

Proposed solutions
to this problem

range from using wood to build

like this 18-story one
in Norway,

to injecting CO2 back
into concrete as it cures,

like this company in New Jersey
making pavers.

And even growing cement using

though scaling up those ideas
remains a challenge.

Maybe the solution,
or part of the solution,

to greenhouse gas emissions
and global warming will come

from a breakthrough
in chemistry.

That may sound foolishly

but the discovery of a chemical

over a hundred years ago

changed the trajectory
of humanity,

though few know the story.

At the start
of the 20th century,

farmlands like these didn't
look so verdant.

And with populations rising,

scientists wondered whether,
in the near future,

there would be enough food.

The problem was nitrogen.

Animals need nitrogen to grow.

So do plants.

But before the 20th century,
farmers mainly depended

on compost and manure to supply
it to their crops,

essentially recycling nitrogen
from dead plants and animals.

But there was only so much
nitrogen in that cycle.

the growing population

would exceed the farmlands'
capacity to grow food,

leading to mass starvation.

But there was a solution in the
air... literally.

Our atmosphere is almost
80% nitrogen

but that doesn't do plants
any direct good.

That's because it's in the form
of N2,

two nitrogen atoms sharing
in a triple bond.

Three electrons from each atom
are fully shared between them,

which as Ed Cussler, a
chemical engineer and professor emeritus

at the University of Minnesota

makes the nitrogen molecule
one tough cookie.

So the atmosphere
is 78% nitrogen.

Why can't the plants just take
the nitrogen out of the air?

Because you can't
break this little bastard in half.

You take the nitrogen,

you have to break
this triple bond,

between the two nitrogen atoms.

It's almost the hardest bond,

the most difficult bond
that we know.

Basically it's almost inert.

So the scientific challenge was
for someone to find a way

to take that stubborn nitrogen
molecule from the air,

and bust it apart to create
something plants could use...

to invent
a synthetic fertilizer.

Around 1910,

German Chemist Fritz Haber
and his team found the answer,

which they demonstrated using
this table-top machine.

From nitrogen gas
and hydrogen gas,

he could produce NH3...

A fertilizer itself,

and a starting point
to produce others.

German chemist Carl Bosch
brought Haber's work

to an industrial scale.

Which is why it is known as the
Haber-Bosch process.

Ed and his colleague,

Joe Franek, show me
their table-top version.

Joe, maybe you can show us

a little more hands-on

how the Haber-Bosch
process works?

All right, we're going to
put a quantity of nitrogen

in this syringe, then
we’re going to put three times

that amount of hydrogen in this syringe,

we're going to light our Bunsen burner

and we're going to
pass that mixture of gasses

over what will be our hot catalyst,

which is iron in this
case, and that will facilitate

the conversion of the nitrogen and
hydrogen into ammonia.

Okay, so one syringe full
of nitrogen

and three times as much hydrogen

because the formula
for ammonia is NH3?

There you go.
It all makes sense.

Joe passes the mixture
over some steel wool

heated by a Bunsen burner.

The steel wool acts
as a catalyst,

a material that helps
a reaction along

while not getting consumed
by it.

After six minutes,

it's time to see if it worked.

So we now have

all of our gases, our
unreacted nitrogen and hydrogen

and the ammonia we
produced in this one syringe,

and what I'm going to do
is flush all of these gases

through our indicator tube.

If we flush some ammonia through
these yellow beads,

they'll turn blue... yeah, bravo.

I see blue!

So how much ammonia
do you think we got?

Well, our indicator on the tube

says that we have just
slightly less than

two parts per million
of ammonia.

Two parts per million?

So out of every million

we got two of ammonia?

At room temperature,

this process barely works,

and even with our burner heating
things up a bit,

nitrogen gas is so inert,

the reaction isn't much better.

Part of the problem is that this
equation is a two-way street.

Some reactions are one way...

When you bake a cake,
you can't unbake it.

But the Haber-Bosch process,
like many reactions,

goes both ways at the same time.

So while some of the nitrogen

and hydrogen
are forming ammonia,

some of the ammonia
is breaking down,

into nitrogen and hydrogen.

The trick is to find the optimal

where that balance heads
in the direction you want.

One tool is pressure.

Bosch's industrialized version
compressed the gases

to around 175 times normal
atmospheric pressure.

And that huge pressure cooker
ran very hot...

550 degrees Celsius, around
1,000 degrees Fahrenheit.

Enough to make the hydrogen
and nitrogen

react with the catalyst,

but not so hot as to break up
a lot of ammonia.

Though the process requires
extreme conditions,

the discovery of a way
to split apart

that stubborn nitrogen molecule
changed the world.

It opened the door
to the creation

of artificial fertilizers.

And it's hard to overstate
the impact

of the Haber-Bosch process on
our ability to feed humanity.

What were the lasting effects
of this introduction?

Two billion more people.

If you lose
this chemical fertilizer,

you lose two billion people...
They starve.

This is not a hypothetical issue.

Haber-Bosch is the chemistry
that you wish for.

Because it's the chemistry

that improves the amount of food
that you can grow

on our planet.

And that makes an enormous

to the stability,
the health, the wellbeing

of the people on the planet.

So one chemical reaction

wound up radically
changing humanity...

Yeah, some people argue it’s the most,

it's the most important single
chemical reaction.


But before you go out
and hug your nearest

chemical plant,

you may want to consider
the downsides.

Now that fertilizer is abundant,
growers often apply too much.

Runoff fertilizer has led
to giant algae blooms

and dead zones in oceans.

Also, making ammonia uses a lot
of fossil fuel.

Annually, the industry as a
whole accounts for one percent

of global CO2 emissions.

Ed Cussler is part of
a team of scientists

at the University of Minnesota

working on a greener approach
to producing ammonia.

This is the industrial
Haber-Bosch process

in a smaller package.

This ammonia reactor here is
making about

25 tons of ammonia a year.

A standard commercial
ammonia plant

is making thousands
of tons a day.

Oh. So this is a
much smaller scale.

It still depends on high
temperature and pressure

but it's powered
by nearby wind turbines.

You're taking nitrogen out of the air.

You're making hydrogen out of the water.

You're making it out of nature.

Yup, right here in this room.

The long-term vision

is that small facilities
like this pilot plant

could make enough
"green" ammonia

for a county's worth of farms...
In this area,

about 130,000 acres.

We are making fertilizer
from air and water.

It's just straight alchemy.

You're not going to get rich
doing it in the new green way,

but you can sure make a

in the way the planet is.

Scientists estimate
that 50 percent of the nitrogen atoms

in any person alive today
at one point

passed through
the Haber-Bosch process.

Yet Fritz Haber's legacy
is mixed.

He won the Nobel Prize in
chemistry for his discovery

but is also considered the
"Father of Chemical Warfare,"

having proposed and supervised
its use in World War I

by the German army.

Some historians believe that

the Haber-Bosch process itself

may have extended that war
by years,

because it gave Germany a
new source of nitrogen compounds...

key ingredients in explosives.

What makes them "key"?

It all goes back to that
stubborn nitrogen molecule.

Think of it like a spring.

Pulling the atoms apart
takes a lot of energy.

And sticking them into
nitrogen compounds keeps them separated.

But in explosives,

those compounds are designed
to fall apart quickly,

freeing the nitrogen atoms to
spring back together...

...and releasing the stored energy
from pulling them apart.

Seems like a good place
to blow stuff up

without risking hitting

Yeah, that's why we like

having our surrounding mountains.

To better understand the role

of nitrogen compounds in

I've decided to return to see
some old friends,

the engineers and scientists

at the Energetic Materials
Research and Testing Center

at New Mexico Tech.

We've had some fun in the

Well this is the most
fun tailgate you'll ever come to.

So let's see

what ordinance tech
Jonathan Myrkle

and chemist Tom Pleva

have in store for me today.

It's... cotton?

Cotton balls?

That's correct.
Like, cotton balls?


Now you might think that
cotton balls don't explode...

And you'd be right.

That was underwhelming.

Cotton fiber is about
90 percent cellulose,

a key structural component
in green plants

composed of carbon, hydrogen,
and oxygen, but no nitrogen.

So our cotton balls will burn...

Eventually... though not explode.

The spores are erupting!

But back in the mid-1800s,
chemists discovered

that they could add to
cellulose what are called "nitro groups,"

each a nitrogen
and two oxygen atoms.

That turned it into

also called gun cotton.

Those nitro groups made

that burns like this...

into something that burns
like this...

flash paper.

But nitrocellulose is no joke.

In a confined space, like a gun
barrel, it can be powerful.

It was the propellant
the military used to launch

the shells out of these 16-inch guns
on Iowa-class battleships.

And it's still a propellant

in 155-millimeter artillery.

Our next test...


Is 50 pounds of
nitrocellulose propellant,

the kind used in those
large-bore guns.

We give you 50 pounds
of gun cotton.

Since the sphere container isn't
sealed, it won't explode.

Delivered unto the earth.

But what will happen?

After Jonathan wires it up,
we head

to a nearby bunker to find out.

Here we go.

Three, two, one...

Compared to plain cotton,
this is a show.

The burning nitrocellulose

generates rapidly expanding gases,
including carbon dioxide,

carbon monoxide, water vapor,
and, of course, nitrogen.

It's pretty.

Packed behind a shell
in the barrel of a gun,

the pressure from the
expanding gases would hurl

the shell forward.

In our open bowl,
it's more like fireworks,

with the gases sending
burning pellets up in the air.

That's just a propellant.

That's a low grade here.

We're going to move
onto actual explosives now.

Oh yeah? Yeah.

What's first up?

So we're going to start off with ANFO.

That is the biggest
mining explosive that we have.

Oh, cool!

ANFO is an industrial
explosive used in mining and construction.

It accounts for about 80%
of all the explosives used

in North America.

Probably no chemical
shows better the intimate relationship

between fertilizer
and explosives.

Though the name ANFO stands for
ammonium nitrate and fuel oil,

it's over 90% ammonium nitrate...

the same stuff
as synthetic fertilizer.

Ammonium nitrate is built around
nitrogen atoms

so it packs way more nitrogen
than nitrocellulose.

That means ammonium nitrate
can be very dangerous.

This is the aftermath of the
deadliest industrial accident

in U.S. history,
the explosion of over

2,000 tons of ammonium nitrate

aboard a ship in Texas City,
Texas, in 1947.

In 2020 in Beirut, Lebanon,
there was similar explosion.

A waterfront warehouse
containing thousands of tons

of ammonium nitrate caught fire
and detonated.

The blast killed over
200 people, injured thousands,

and left an estimated 300,000

Our ANFO test will be just
50 pounds of the stuff.

50 pounds.

To get a reaction going,

even one that will release
a lot of bang,

you need to put some energy
into it first

to get some of the bonds
to break.

That's called activation energy.

This is nitrogen triiodide,

an explosive whose existence

is so precarious...

...minimal activation energy
is needed.

Even just the touch
of a feather.

In contrast,
ANFO is hard to set off.

So Jonathan hooks up a booster...
A smaller explosive.

Since much of EMRTC's
research and training involves explosions

in human-occupied environments,

they typically add
a wooden dummy for scale

and to demonstrate
an explosive's effect.

- You good?
- Good.

Okay here we go.

Three, two, one...

That, my friend,
is a firecracker.

That was like seven stories.

So, what just happened?

Jonathan ignites the booster...

...that's the black smoke
you see.

The pressure wave from the
exploding booster, in turn,

detonates the ANFO,

breaking the bonds holding
the ANFO atoms together.

They rearrange into more
stable gases...

nitrogen, carbon dioxide
and water vapor,

along with some carbon monoxide
and nitrogen oxides.

The hot gases rapidly expand,

creating a supersonic shockwave

traveling at about two miles
per second.

If you look at just the
nitrogen atoms of the ANFO,

it's like the un-Haber process.

Most of the nitrogens from the
ammonium ions and nitrate ions

reunite into their more stable
preferred state, N2.

In fact, about half of the power
of the ANFO explosion

comes from nitrogen atoms

reforming into
nitrogen molecules.

Here we are, what,
a quarter of a mile away?

And you could feel the ground shaking.

Yup. And that's 50 pounds.

That's only 50 pounds, yes.

Next up: you've seen it
in movies...

...and you probably even know
its name.

- What's that?
- That's C-4.

And just one look
at its active ingredient

should tell you
we've upped our game.


commonly known as RDX.

While it has three nitro groups,

there's even more nitrogen
built into its ring.

And even though
the nitrogen triple bond

is one of the strongest
in nature,

the single bonds between
the nitrogen in the ring

and the nitro groups
are rather weak,

often the first to fail
when detonated.

Oh my...

The last one for the day for us.

Ah, yeah, 50 pounds of C-4.

All right.

Should I be offended that...
they've dressed him like me?

Is there a
hidden message in that?

I wouldn't take it personal
but... you know.

All right.

Oh wait, I've gotta go do that...

Oh, but it looked so cool!

I know, I know...


Okay, here we go.

Three, two, one.

Oh, my God!

When the detonation pressure
wave hits the RDX molecule,

the ring compresses
and then flies apart.

The atoms recombine into
carbon monoxide, water vapor,

and nitrogen gas.

Those reactions produce
far more heat than ANFO does,

which makes the gases expand
much more rapidly,

giving RDX over twice
the explosive power.

So we have more heat and energy
in there.

And there's more nitrogen in there.


Does that mean that the future
is just all nitrogen?

That is the goal.

We are trying to make
entirely nitrogen-composed

explosive molecules.

Here's one from the drawing
boards with a great name:


Entirely made of nitrogen,

it is predicted to have a
faster velocity of detonation

than any known non-nuclear

if someone can just figure out
how to make it.

I think that's all that's left.

And so ends our day of the
un-Haber-Bosch process.

Much of the nitrogen
in our explosives

has returned to its happy,

or at least extremely inert,

as N2 molecules in the
atmosphere over New Mexico.

In chemistry, reactions tend
to consume other ingredients,

transforming them
into something new.

That's the process that
chemical equations

are designed to explain.

But in biology, molecules can
sometimes bind to each other

without consuming or producing
anything new.

They can act as triggers
or messengers.

Or, as it's sometimes described,
like a key fitting into a lock.

To learn more about molecular
"locks and keys,"

I've come to experience them


Oh! Wow!

Here at the Berks Pepper Jam,
in Bethel, Pennsylvania.

Smell that! Mm!

An annual festival of food,

entertainment, and contests...

all centered on chili peppers.

Reaper Evil hot sauce.

They do have an ambulance
on hand, right?

They do.

When it comes to peppers,
I'm a novice.

But the first thing you need to
know is that the black pepper

you see sitting with salt,
and chili peppers,

have different chemistries
and histories.

Black pepper is the dried
ground-up fruit

of a flowering vine
native to Asia.

Its kick comes mainly from
the molecule piperine.

While one side of the world
had black pepper,

the other side had
chili peppers...

first domesticated
by Mesoamericans,

and then traded around the world
by European explorers.

The main active ingredient
in chili peppers

is the molecule capsaicin.

More on that in a bit.

Three, two, one... eat!

The Jam features
a pepper-eating contest...

for kids,
but they wouldn't let me in.

So I plan on entering
the one for adults...

after I get some advice.

I've actually never eaten
a pepper by itself.

Bow out when you feel
you should.


A raw pepper is a
completely different deal.

I can't do it.

You can't eat a reaper?!

Is there any way I can prepare?

Well, drink water...

You got your will made out?

You don't have anything to
do for the next three days, do you?

Yeah, you're going
to feel great Monday morning.

A big round of applause
for Lizzie.

Well done!

Time to put my tongue
to the test.

Long hots, red Fresno...

Here's how the contest works:

there are ten rounds of
increasingly hot peppers...

Peach Copenhagen...

Big Red Mama.

Their spiciness measured
on a scale

invented in 1912 by pharmacist
Wilbur Scoville.

It estimates the amount
of capsaicin in each pepper.

Contestants have to eat
a pepper...

and then wait two-and-a-half

to allow the burn to grow.

If they drink the milk
in front of them...

a popular way to douse a tongue
on fire...

They are eliminated.

They're out.

My competitors include some
rugged-looking characters.

And Leah...

I've never done this before.

I figured this out
two hours ago.

A 15-year-old who entered
with the permission

of her parents.

Whoo! Bring it on!

We begin our contest

with the long hots...

Let's turn up the heat!


And we're off!

Zesty, with just a hint
of poison.

Round two we're going to start

with the red Fresno pepper.

Eat! Eat! Eat! Eat! Eat! Eat!

There's got to be some easier
way to learn about molecules.

All right, are we ready? Eat!

That was not designed
for human consumption.

Habanero peppers.

Parts of my body

I didn't know I had are on fire.

- Ten more seconds.
- You got this.

I can't, I can't.

No! Don't do it! No!

The orange Copenhagen pepper.


What am I doing?!

Oh man...

Oh my God!

Don't do it!
I want it!

Wherever you are, Scoville...
I hope you rot!


So I'm the first to fall...

Thank you.

Is there a Port-A-Potty?

But there's a bigger mystery...

How does a pepper's
capsaicin convince my mouth it's on fire?

Not recommended.

I think I'll find
the answer here

at Penn State University's
Department of Food Science.

We all study food.

So you have psychologists,
and microbiologists...

I'm here to see John Hayes.

He knows a thing or two
about the active ingredient

in these.

So when you went and tasted
them, what did you experience?

Oh, man.

My gut twisted,

my tongue burned,

my flesh burned, I cried,

I got red, my nose ran.

It's like putting your
tongue on the stove and leaving it there.

That was an aversive response.

This plant has evolved a
chemical called capsaicin.

And the reason it makes that

is to keep animals from
eating the chili pepper.

Oh man, the chili festival
people never got that message.

And we're just a
really stupid species?


We're one of the only
species that learns to like

that sensation.

Ultimately, pepper
plants are playing a pretty good trick

on humans as well.

Capsaicin really is a "key"

It has a long spindly tail
attached to a ring.

That ring end fits into
a specific receptor

that's expressed all over your body.

Not just our tongue?

Not just your tongue.
Oh man.

This receptor, this lock, is
actually a heat pain sensor.

Normally the receptor,
called TRPV1,

activates when it comes
in contact with something

over 106 degrees.

The result is a pain message
to the brain.

"Ouch! Something's hot!"

It's a warning signal
to tell your body, "Danger."

And here's the tricky part:

when you eat peppers,
those capsaicin keys

fit into the heat pain receptors
in your mouth,

altering their sensitivity.

And so, what the
capsaicin does is it fits into

this molecular thermometer,

and it lowers the temperature at
which it activates it.

Like a changed thermostat,

they now activate
at body temperature,

sending a false signal
that’s identical to the one your brain

would receive if you
ate something literally burning hot.

It lowers the temperature at
which we feel burning pain...

Yes. but it's not
actually burning us?

Correct. It's not... I'm not
going to see scar tissue...

No. No matter how hot
it is, it's all a fake-out?


Up next...

the Yellow Seven Pot pepper.

Back in Bethel,
the pepper-eating contest

is entering its final rounds.


That was warm.

Oh, it's burning now.

I'm trying to think
of a happy place.

I can't find one.

Evidence that capsaicin's
working on

the molecular locks of
everyone's heat pain sensors

is easy to see,

as they eat a Big Red Mama,

rated at over a million
Scoville heat units.

Don't tap out now!

Don't tap out!

One more falls.

We're down to the final four.

I'm ready to leave.

I can't abuse these people

This time, the organizer adds
concentrated pepper extract.

How long can this go on?

Then suddenly a resolution
that no one saw coming.


Leah beat 'em!

Big round of applause!

Big round of applause.

Leah, I am not worthy.

You rock!

What does a woman with that
fortitude and strength

want to be when she grows up?

A fighter pilot.

Why am I not surprised?

Ultimately, the capsaicin
molecule is an illusionist,

able to trick my nervous system

into thinking my mouth
is on fire.

But what about the molecules
that pose real danger?

Molecules designed by nature
to kill?

Time to meet my first professor
of venoms...

Mandeë Holford
of Hunter College.

Now, I couldn't help noticing,

there's a huge, terrifying tarantula on me.

Is she poisonous?

No, no,

she's not poisonous. Oh, whew!

She is, however, venomous,
and could still be lethal.

Thanks for bringing that up.

Poisonous and venomous don’t
mean the same thing?

No, no, no, not at all.

Poisonous versus venomous:

it all comes down to
the delivery system.

If you bite it and get sick,
it's poisonous.

But if it bites you and you
get sick, it's venomous.

In general, the source of their
toxins is different as well.

This poison dart frog becomes
poisonous from its diet.

If raised in captivity
on different foods,

it can become non-toxic.

Whereas this rattlesnake
generates its own venom.

It's built into its DNA.

So snakes,



which fearsome creature is the
focus of Mandeë's work?



Is it accurate to say that you
study killer snails?

Killer snails are actually
my affectionate term

for venomous marine snails.

And so these are snails
that live in the sea,

and they have a venom,

like snakes or scorpions
or spiders,

and the venom can be very lethal
to humans.

It's true that the snail
can kill you.

But usually it's just
looking for dinner...

a worm or a fish.

So I'm a fish.

What happens to me?

Well, what happens is
this guy will smell

that you're in the water, right?

He puts out something
called a siphon,

and it's a chemosensory organ.

Smells that, "Hmm,
tasty meal in the water."

Then it sticks out something
like a tongue,

it's called a false tongue,

And on the tip of the tongue,
it has a little tooth,

filled with venom

that then will get injected
into the fish.

The fish instantly will become

depending on what cocktail of
venom gets injected into it,

the snail will then open
its mouth really wide,

swallow the fish whole and have
a really nice, tasty meal.

The whole thing sounds
so improbable.

I love it.

Just when you think you've heard
of everything,

nature will surprise you
with something new.

So what's in that
paralyzing venom?

To find out, Mandeë and her team

collect specimens from around
the world.

Back at the lab,

they analyze tissue samples
from the snail's muscular foot

and its venom gland.

So we're eventually going
to look at the DNA,

so we can make a species

And that we can use
the foot tissue for.

And then the venom gland tissue,

we can use to look for
the individual

venom toxins within
the venom duct.

Turns out the cone snail's venom

isn't one thing, but a cocktail

of as many as 250 short "mini"

also called peptides.

So if you think of venom,

think of it not as like
a single bullet, right?

It's more like I like to
describe it as a cluster bomb.

It's a series of bullets

coming at you and each
individual bullet has a target

in the physiological system.

Each venom peptide has
evolved to mount a very specific attack,

often acting as keys that fit
a cell's lock-like receptors.

In the case
of the nervous system,

that can prevent
a specific neuron

from transmitting an impulse.

Or, conversely,
jam the neuron open,

generating a flood of signals.

In the wild,
all those targeted attacks

paralyze the snail's prey,

but the precision with which
the venom peptides act

also means that they may have
another role as medicines.

And so we study these venoms
to try to figure out

novel medicines for treating
things in pain and cancer.

Actually, they make great drugs

because they're highly specific,

very fast-acting,
and very potent.

A venom curing
instead of killing?

Wouldn't be the first time.

There are currently at least
seven drugs on the market

developed out of the study
of venoms.

They include an anticoagulant
derived from medicinal leeches

and a diabetes medicine
from Gila monsters.

There's even one already
from cone snails,

an analgesic to treat
severe chronic pain.

And it's the exact peptide that
you would find in the venom.

It's not a derivative of it,
it's not a small molecule,

it's exactly as nature
expressed it

in the animal.

And I'll just run a
simple DNA extraction...

Mandeë's team has already made
some major breakthroughs.

So I could do a nano LCMS
and see what's inside of here.

In 2014, they identified
a peptide from another

venomous snail that attacks
liver tumor cells,

inhibiting their growth.

It's cutting-edge work
that’s reaping the rewards to be found

at the intersection
of chemistry and biology.

Learning how the venom is used

more in ecological settings helps
to further us in terms of

how we understand how it can be
applied for medicinal

or therapeutic applications.

And so right now, it's a fun
time to be a venom scientist

because those worlds
are colliding.

In both chemistry and biology,

change is a story told
through reactions.

And understanding
those reactions

has given us new insights

into both our world
and ourselves.

If you lose this
chemical reaction,

two billion people starve.

This is not
a hypothetical issue.

And with that comes a lesson.

Oh man!

Just as a molecule can act
as both a venom

and a medicine...

or one reaction can both
help feed the world

and blow it to bits...

...our scientific knowledge
is a powerful tool.

The power of bacon!

But it's up to us to learn
how to use it well

as we continue to go
"Beyond the Elements."

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