I am a planetary astrophysicist.
(Cheers) (Applause)
Thank you.
But I will be the first to tell you that I made that title up.
(Laughter)
You see, I had to make up a title to describe what it is that I do.
So I got my PhD in astrophysics
because I look at the properties of stars that are near to the Sun.
But I also look at planets and how those planets and stars interact.
You see, up until about 25 years ago, the term "planetary scientist"
meant only people who studied the planets within our own solar system.
But it was in 1992 that the first planet outside of our solar system,
or exoplanet, was discovered.
So, there's no name for somebody who studies what I study,
and today there are 3,593 known exoplanets.
(Whoo!)
It's a lot.
So this field that I'm in, it is very young.
If it was a person, it would barely be old enough to drink.
(Laughter)
Whereas astronomy in general, which is the study of celestial bodies,
has been around for thousands of years.
It is the oldest of the natural sciences.
So today we're only just learning
about all the crazy possible planets that can exist out there.
There are some planets that actually share a star,
so they have two stars over the same one.
And there are some, like what you see on this picture,
that are so close to their planet that they have a period of ten hours.
The Earth's period is 365 days.
So that's pretty nuts.
So we're only just now really beginning to understand
all the weird physical and geometric properties
that exist between a star and a planet.
But I don't look at just how a star and a planet move
with respect to one another.
I study how they chemically interact.
But let me explain.
From the Big Bang, the only elements that we got were hydrogen and helium.
So there is none of these carbon or oxygen or iron.
There's none of that.
So what happened was that the Big Bang went off,
and there was hydrogen and helium shot all over the universe.
But it did so in an uneven way
until it formed these giant pockets of gas,
which is sort of what you're seeing in this video.
Eventually this gas collapsed in on itself and formed stars.
But these stars were massive, they were just absolutely huge.
They were about a thousand times bigger than the Sun.
(Laughter)
So this is like saying our Sun is a grape, and these massive stars were as a cat.
(Laughter)
Except less furry.
But it was within these first stars that you were able to have
high enough temperatures and densities that you had fusion.
So for the first time, elements were slamming together, and they were sticking.
So you have hydrogen, which has one proton,
and helium, which has two protons,
and they slam together, and suddenly you have lithium,
and then beryllium, and then carbon.
But these first stars, they lived hard and died young,
so they exploded out everywhere.
But they took all of these new elements that they created inside of them,
and they shot them out, also into the universe.
So a second generation of stars was formed mostly out of hydrogen and helium,
but also with these seeds of carbon
that they could continue the process of fusion.
Our Periodic Table was compiled by looking at stars
who lived and died at different times.
This one here is color-coded and was done by a colleague of mine, Jennifer Johnson,
and what she did was she color-coded it
to show the different ways in which these elements could be formed.
So you see that a few of them are blue because they came from the Big Bang,
but most of them come
from either two stars circling each other and then exploding,
or just one exploding as a supernova.
So, our Sun is created out of the original hydrogen and helium from the Big Bang,
but also out of many of these elements.
And at the same time that the Sun was formed, were also planets.
So that's everything from Mercury to Neptune,
even the dwarf Pluto.
But it was on the Earth that life blossomed,
and out of that life came humanity.
But our humanity is really rooted in the properties of our planet.
So when you think about it, people are made up of raw ingredients,
these elements that are so basic to life, which were created in stars.
We are carbon-based beings, the bones made of calcium.
And we walk on iron silicates on the ground,
and we breathe oxygen,
like right now, you're breathing,
I could see it.
(Laughter)
That came from a star.
So we're all stardust.
Quite literally.
But we can also do a thing that is similar to other stars,
in that we can create other elements.
[Tennessine]
(Applause) (Cheers)
For example, tennessine, which you may or may not have heard of.
So this is Ts 117, and it was named after the great state of Tennessee
because a number of Vanderbilt scientists were part of the discovery team.
I'm often asked the question:
"How can you look into outer space
when there are so many problems here on Earth?
Doesn't it make you feel small?"
And my answer to that question is always no.
It doesn't make me feel small, it makes me feel empowered.
Because I know all of the things, all of the events
that might have happened,
and all of the events that did happen in order to create life.
You see, it's important for us as people to know where we came from,
whether it's our parents, our ancestors, our planet, the birth star,
or the stellar nursery.
Knowing our root is a fundamental drive that is so important to humanity.
And it's by using the scientific method
that we're able to come up with a hypothesis
that can explain how the solar system got to be where it is today.
So for example, it's currently thought that a supernova must have gone off
4.6 billion years ago as the solar system was forming.
We're then able to collect data about nearby stars and planets
such that we can understand their basic properties.
So now we've found that there are specific elements in meteorites,
and also at the bottom of the ocean,
that could have only come from a supernova.
There, and with the help of our peers reviewing our data,
we're able to deduce the fact
that this supernova must have acted like a huge blender.
So it took the gas, and the dust, and all of these new elements,
and it swirled it together until it made something
that was palatable or habitable for life.
It's by looking at thousands of planets
and millions of stars
that we're able to see what a unique cocktail of basic elements was needed
in order to create a planet that could sustain life.
Then there were even more unique circumstances that were needed
to create that life.
In other words, we are a mathematical anomaly,
a rarity in the universe.
And while there's probably life in the universe,
maybe even our Milky Way galaxy,
that life is going to be inherently different from our own
because they were affected by events that never happened for us.
And it's going to take quite a lot to actually detect that life
because we need to be able to find, fund and develop the new technologies.
So thinking about the statistical likelihood of our existence,
it doesn't make me feel small,
it reminds me of all the possibilities that exist in outer space.
When we were undergrads, we'd walk at night from the library to the dorm,
and we'd look up at stars.
And I'd look up at Orion in particular.
In our classes, we learned that two stars that are shooting through space,
they're probably never going to collide, no matter the circumstances.
And that the inside of a star has a structure like an onion,
it's like shells.
So over time, I realize that these constellations
changed from being just these dots in the sky to being distinct characters.
I could see them, being at different distances from us,
and they shone in different colors,
and they were rotating at different speeds.
Some of them had planets that were so close to them
that it was hard to fathom.
And others shared their planet with another star.
When you look up in the sky,
it's like zooming from the Earth into outer space.
Except, instead of seeing data or pictures,
you're seeing questions and possibilities.
Regularly looking outside of our world
gives you a perspective that's so easy to forget.
There were so many events that had to happen
in exactly the right sequence in order for me to be with you today.
If even one of those things was different, say that the Earth was closer to the Sun,
or that the Moon didn't exist, then maybe life wouldn't have happened.
Realizing the statistical odds of our existence,
it helps to have all of the day-to-day drama,
anxieties, and insecurities just fall away.
It reminds you who you are.
A mathematical anomaly in a sea of gas, stars and planets.
And what I do is I study those stars and planets in order to try to understand
how they formed and how they evolved.
And maybe, just maybe, to discover life.
But you don't have to be a planetary astrophysicist
in order to feel inspired or empowered by outer space.
All you need to do is look up and remember that there are so many things going on
outside of the right here and the right now.
There's stars being born,
planets colliding,
galaxies rotating,
all of which are beautiful as you can see.
And they have nothing to do with you.
(Laughter)
Or so you think.
But these were the exact events that had to happen
in order for the Milky Way galaxy to be formed,
for a supernova to go off,
for the Earth to rotate around the Sun,
and for us to exist.
Thank you.
(Applause) (Cheers)