Hi, I’m Emily Graslie and welcome to Crash
Course Big History.
Today we’ll talk about why something as
distant as cosmology and stellar chemistry
is deeply intertwined with humanity: our past,
present, and future.
When we start the grand narrative of thirteen
point eight billion years, our minds are blown
by the incomprehensible mysteries of the Big
Bang and the vast size of our Universe.
We then spend some time looking at the birth
of the chemical elements in stars.
It is very tempting, sometimes, to look at
this stellar chemistry and think, “alright,
alright, when do we get to the dinosaurs?”
Or, “when do we ditch all this science stuff
and get to humanity?”
But before we get there, to illustrate just
how important chemistry is to the grand narrative
I’m going to pick just one of the elements
from the periodic table to show you just how
crucial “star stuff” is.
Get ready for a “little” big history.
This is the story of our intrepid hero, Carbon.
The Universe had begun with a bang.
About 3 minutes later, the first protons and
neutrons formed into the nuclei of hydrogen
and helium, our two lightest elements, effectively
Carbon’s mother and father.
Then, the Universe cooled down too quickly
for new elements, other than slight traces,
to form.
That said, the Universe was still an oppressive,
murky sea of radiation from which not even
light could escape.
Hydrogen and helium nuclei couldn’t even
become fully fledged atoms.
Let’s fast forward about three hundred eighty
thousand years, and go to the Thought Bubble.
(1) The universe cooled down enough for the
young hydrogen and helium nuclei to capture
electrons and become fully fledged atoms.
(2) Hydrogen and helium became the dominant
forms of matter in the Universe.
(3) But for now they were wispy gases, airheads
without much structure or complexity.
(1) Fast forward again, about 100 million
years.
Slight inequalities in the distribution of
hydrogen and helium allowed them to clump
together.
Gravity sucked more in.
And more, and more, until there was so much
pressure that the first stars were born.
(2) The hydrogen and helium inside them were
squeezed together so tightly they fused to
create lithium, then beryllium, boron, and,
finally, Carbon was born.
More stars created Carbon, along with heavier
brothers and sisters all the way up to iron.
As the first stars began to run out of fuel,
they exploded.
Carbon and its siblings were scattered out
into the void.
All of the heavier elements, like gold and
uranium, were created.
About six hundred million years after the
Big Bang, Carbon and its siblings, along with
millions of stars had grouped together into
a very young Milky Way.
Over the next 3 billion years, more stars
joined the party in a series of galactic mergers,
creating the swirling cosmic island we call
home.
Then about 5 billion years ago, about a light
year or so away, a giant star collapsed into
yet another supernova, peppering our neighborhood
with more Carbon and other elements and triggering
the formation of our Sun.0
About 99% of Carbon declared early retirement
and made its home in the warm embrace of the
Sun,
but a sliver of Carbon wound up on the orbital
track of where our Earth is.
It was rolled up over the next few million
years, with all the other elements, into what
eventually would become our planet.
Thanks, Thought Bubble.
The Hadean era was a real mess.
The Earth was bombarded by asteroids, was
full of volcanoes and the sky was red.
Over time, heavy elements like iron and nickel
sank to the Earth’s core, while lighter
elements like Carbon floated upward and were
belched out of early sky-scraping volcanoes
as a gas.
Some carbon combined with oxygen forming carbon
dioxide, and there was so much of it in the
atmosphere that it turned the skies above
that volcanic landscape red.
More solid forms of carbon can be found in
the Earth’s thin crust.
Only a small amount of the Earth’s atmosphere
and crust, a fraction of a percentage point,
is made of Carbon, paling in comparison to
the vast masses of oxygen and silicon.
But carbon is stable, and this makes it one
of the most flexible of all the elements when
it comes to forming molecular combinations
of other elements.
In a way, carbon forms the keystone of most
molecular complexity.
It is estimated that, without carbon, about
95% of all molecular combinations would not
exist.
Without carbon, complexity probably would
never have increased much further beyond the
most basic chemistry.
We’d have stars, we’d have gases, and
we’d have metals, we’d have a few basic
minerals.
And not much else.
No life, no complex chemistry, no “us”.
And because Carbon is so ready to bond with
other elements, it became the prime candidate
for self-replicating organic chemicals that
would one day, approximately 3.8 to 4 billion
years ago, become life.
Carbon can bond easily with oxygen, hydrogen,
and nitrogen — all abundant on Earth and
all crucial for life.
Carbon tied them all together.
Because it’s so flexible, carbon can be
used to stick together extremely long molecules,
a handy thing when you consider how complex
the molecules required to sustain life are.
Carbon-based life began as single celled organisms
in the ocean, evolving into photosynthesizing
bacteria near the surface of the sea.
This bacteria would evolve into multicellular
plants, at first in the sea starting six hundred
and thirty five million years ago, and later
with the plant-based conquest of the land
some two hundred million years later.
The plants in your garden, and those you eat
for dinner are about 45% Carbon.
Given that we eat so much Carbon, you could
argue that without it, you would starve to
death – not that you would have evolved
in the first place.
Plants also need carbon, taking in carbon
dioxide and expelling the oxygen as a waste
product of photosynthesis.
The process of photosynthesis led to a massive
increase in oxygen in the atmosphere about
2.5 billion years ago.
The by-product was that other Carbon based
bacteria began to harness oxygen’s energy
and evolve into more and more complex forms.
This includes fish, frogs, dinosaurs, lions,
tigers, bivalves, and you.
The entire evolutionary epic of nature, multi-celled
organisms, predators, prey, and all the survivors,
owe their existence to carbon.
Your body is 65% oxygen, 10% hydrogen, 3%
nitrogen, and a smattering of calcium, phosphorous,
potassium, sulfur, sodium, chlorine, and magnesium.-
and all of it is held together by 18% Carbon.
Carbon rich plants played a key role in human
history.
It was in everything from the crops we ate,
to the wood houses that provided shelter,
to the wood we burned to cook for energy,
to the even more energy dense charcoal which
we used to build our cities and grow our technology.
If carbon could not be manipulated in this
way, it is likely the past 10,000 years of
history would have never happened at all and
we would still be a few million foragers with
stone tools wandering around the Earth.
Without the internet.
Carbon is also responsible for one of the
greatest leaps forward in 13.8 billion years:
the rise of complexity in the modern era and
the Anthropocene, where we have created systems
more complex that harness a greater density
of energy than anything else we see in the
Universe.
From microscopic photosynthesizing bacteria
to the giant forests that existed in the Carboniferous,
all inevitably died, and some were buried
by the soil, protected from rotting, and sank
over millions upon millions of years as more
soil fell on top of them.
As these plants sank deeper and deeper into
the crust, the pressure made temperatures
rise.
This pressure and heat converted plants into
coal.
Coal was used by humans as a source for starting
fires as early as 1000 BCE, but the noxious
smoke it gave off made wood preferable for
a long time.
So, coal was the second choice.
Ancient civilizations definitely knew about
it, though.: the Latin word used by the Romans
for coal was Carbo.
Then, when the Industrial Revolution was still
in its infancy in Britain, a shortage of wood
for increasing fuel demands prompted the British
to turn to coal.
In 1709, Abraham Darby enhanced steel production
by using coke derived from coal instead of
Charcoal.
In 1781 James Watt produced a commercially
viable steam engine that found its way into
the engines of all manner of production and
rail transport.
From there, industrialisation spread across
the world, tying all humans together more
closely in a human network, exchanging and
producing more ideas, accelerating change,
and skyrocketing the concentration of energy.
All thanks to little Carbon, in the form of
coal.
Even today, approximately 43% of all energy
production is the result of coal.
With the Industrial Revolution, largely ignited
by the spark of carbon, came goods that could
be produced more cheaply - which was great!
Luxury goods transformed into everyday staples,
the carrying capacity gradually lifted, and
people found more opportunities off of the
farm.
The immense tapestry of ideas, advancement,
and trade of today – the next rise of complexity
– owes itself to carbon.
Nowadays, we also make huge use of other fossil
fuels like oil and natural gas.
Carbon-based marine life hundreds of millions
of years ago died, sank to the bottom of the
seas and oceans, and were buried deep in the
silt.
With such intense pressures, the carbon was
transformed into either a black sludge we
call oil or heated to such high temperatures
that they became natural gas.
This shapes not only global production, and
directly impacts our quality of life – from
transport, to our everyday goods, to the myriad
of plastic products we use and depend upon
– it also shapes modern day politics, with
the oil-rich nations and oil-dependent nations
directly influencing the daily tide of events.
Ironically, though, Carbon may also prove
our downfall.
One of the greatest threats to human complexity
today is our dependence on these fossil fuels.
The carbon dioxide they release into the atmosphere,
which raises the average surface temperature
of the Earth and will cause a great deal of
environmental problems and human suffering.
If disaster strikes as a result, Carbon, which
was so crucial to the rise of complexity in
Big History, may bring complexity down to
a crashing halt.
But some forms of Carbon are a little more
benign- like, in the form of graphite, an
extremely soft material that you might find
in your pencil.
Sometimes graphite is used to help conduct
electricity.
And at the other end of the spectrum, the
hardest known material is diamond, also a
gift from Carbon.
Crucial to all sorts of advanced machinery
like electrical insulators and thermal conductors,
diamonds are perhaps best known as a pricey
rock that saw its value skyrocket in the 1930s.
This was thanks to a highly successful advertising
campaign by a diamond company that convinced
a lot of people to spend a month’s salary
on a shiny rock in order to propose marriage.
This led to a tragic exploitation of the environment
and people for the sake of these shiny stones.
So we can think of carbon as both a gift and
at times a curse, depending on the way we
look at it.
Carbon is just 1 out of 92 naturally occurring
elements, a single piece of the puzzle among
many others.
But, Carbon was absolutely vital to the entire
story of complexity in the Universe.
Without it modernity and the heights of human
complexity wouldn’t exist.
The Industrial Revolution wouldn’t have
happened - along with ancient and medieval
civilizations, and the evolution of all plants
and animals.
Remove Carbon from the equation and all that
complexity would not have existed.
Misuse carbon and the fate of human complexity
in the Anthropocene may similarly be doomed.
Without Carbon, the tale of rising complexity
would be a short story, involving stars, space
dust, and barren planets floating in emptiness.
And there would be nobody around to tell it.
In some cases, that story of rising complexity
would not have happened at all.
To quote the great late Carl Sagan: the cosmos
is also within us.
We're made of star-stuff.
We are a way for the cosmos to know itself.
Thanks for watching, we’ll see you next
time.
