This episode was made in partnership with the Kavli Prize.
The Kavli Prize honors scientists for breakthroughs in astrophysics,
nanoscience and neuroscience—transforming our understanding
of the very big, the very small, and the very complex.
[♪ INTRO]
It’s easy to be dazzled by all the shiny, sparkling stuff in space…
and fair enough—stars and galaxies are great.
But the apparent void in the dark spaces between them
is not as empty as you might think.
Most of what we think of as empty space has between one and a few thousand
atoms per square centimeter.
That’s not much compared to the 25 quintillion atoms
in every square centimeter of the air we breathe.
But somehow, it’s enough to enable the chemistry needed to make
all the dazzling galaxies, stars, and planets in the universe.
It even made us.
And the Dutch super-scientist Ewine van Dishoeck has made it
her life’s work to figure out how.
It’s not an easy thing to do—to figure out how a thin soup of gas
and dust turns into structures like solar systems with thousands
of different molecules and the ingredients for life.
For one, these thin clouds of molecules are extremely difficult to study.
Since they’re very cold, they don’t emit much light of their own.
And they’re thin enough that most light passes right through.
But a few wavelengths of light don’t make it through.
Every atom and molecule absorbs certain colors of light, so by
looking at missing wavelengths, you can tell what a cloud is made of.
And in the early 1900s, astronomers began using this technique
to discover lots of atoms and molecules floating between stars.
By the early ’70s, we even had instruments that could
look for these chemical signatures in space.
So, it was a flourishing field when van Dishoeck began her
scientific studies around the same time, and she found herself
drawn to chemistry and space.
After her undergraduate degree in chemistry in Leiden,
in the Netherlands, she started doing research at Harvard,
as a PhD student and later a postdoc.
Then she had brief stints as faculty at Princeton and Caltech
before returning to Leiden in 1990.
All the while, she was trying to home in on the answer to one question:
How does interstellar gas and dust turn into us?
One key part of the equation is carbon.
Life as we know it depends on this element, and fortunately,
space is full of it!
It’s usually locked up in the form of carbon monoxide,
which can combine with other molecules to make the carbon chains
that form the basis of life.
Scientists understood this by the 1980s, but there was a conundrum:
From lab studies, it was clear that carbon monoxide is easily
destroyed by UV light, which breaks the bonds that hold it together.
And thanks to hot, bright stars, there’s plenty of UV light in galaxies.
But somehow, carbon monoxide manages to survive—and no one quite knew why.
So, fresh from her PhD, van Dishoeck took on this problem.
She created theoretical models of interstellar clouds in the lab
and then validated those models against real observations.
And she started to see what was going on.
The key was in the colors that were missing from light
passing through these clouds.
Carbon monoxide isn’t vulnerable to all UV light
—just the wavelengths that it can absorb.
Those are the ones that rupture its bonds and break it apart.
But if light at those wavelengths hits something else first,
then it can’t do any more damage.
In 1982, astronomers had shown that the molecules of carbon monoxide
on the edge of the cloud absorb some of the damaging light,
protecting the molecules further in.
Later that decade, van Dishoeck and her collaborator John Black
found that other molecules, as well as dust, can absorb
some of these same wavelengths and also protect carbon monoxide
from being destroyed.
And in 1988, they combined these findings into a now-famous paper
that solved the carbon monoxide conundrum.
The paper demonstrated that, thanks to protection from other particles
in its environment, carbon monoxide could survive in the midst
of destructive radiation.
And that’s how it stuck around long enough to lend itself to life!
But that’s not the only way that life is rooted in these molecular clouds.
Aside from carbon, one of the other key ingredients to life is water.
And that’s also floating around between the stars.
The problem is, we have so much of it in our own atmosphere
that it’s hard to detect from the ground.
But starting in the 1990s, space telescopes finally made it possible.
Van Dishoeck was instrumental in analyzing data from
the Infrared Space Observatory and Herschel Space Observatory,
which were among the first to look for interstellar water.
And this research showed that these loose molecules of water play
a surprisingly important role in the process of star formation.
Out in frigid interstellar space, most of the water is frozen solid.
And when it encounters dust particles, it attaches to the surface of that dust,
making the dust both stickier and heavier.
Now that they’re more massive, those dust grains attract
more material, setting off a runaway process of growth.
As matter accumulates in a cloud, the region gets hotter
and denser until it can start fusing hydrogen.
And that is how a star is born.
Van Dishoeck also took this a step further and showed that,
many millions of years later, this same process also plays
a central role in planet formation.
Once again, water makes dust grains sticky and helps bring matter
together until there’s enough for a planet.
So, while we might have known that we owe a lot of our existence
to water—the role of water goes back further
than many scientists expected.
These fundamental discoveries about water and carbon monoxide
are just two examples of Van Dishoeck’s incredible efforts
to understand our cosmic origins.
She is the co-author of nearly 500 publications
and peer-reviewed papers, with around 58 thousand citations.
In 2018, she was elected president of the International Astronomical Union.
And that same year, she was awarded the prestigious Kavli Prize
in Astrophysics for her incredible discoveries and her
foundational role in the field of astrochemistry.
The Kavli Prize honors scientists for breakthroughs in
astrophysics, nanoscience, and neuroscience.
The winners have made outstanding progress in understanding
the very big to the very small.
They are transforming our knowledge of the world we live in.
If you’d like to learn more about Ewine van Dishoeck, you can
click the link in the description to visit her page
on the Kavli Prize website.
You can also learn about the winner of the 2020 prize in Astrophysics,
awarded to Andrew Fabian, who made many discoveries, including
a black hole that makes the deepest sound in the known universe.
To hear his story, head over to SciShow Space and check out
the video we just posted there!
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