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>> A black hole is an object where gravity has won.
So what has happened is matter has been compressed at such a
state that it has overcome every normal force that we know
of, and it effectively collapses to a very, very small spot.
Space closes in on itself inside of a black hole.
I'm Karl Gebhardt, I'm a Professor of
Astronomy at the University of Texas.
I study the evolution of galaxies including
black holes and dark matter and dark energy.
Right now, there are about 80, 90
galaxies that have black hole mass members.
I've been involved in probably 50 or 60 of them, and
so I have measured more black holes than anybody else.
The idea of a black hole has been around for a long time,
since the late 1700s, and basically it's a simple
concept, and it has to do with escape velocity.
You know, if you toss a ball in the air on
the earth it goes up and it comes back down.
If you tossed it harder, as fast as you can, it
will go up a little higher and come back down.
You attach a rocket onto that thing,
then it can escape the earth.
Now, just imagine a system where the earth gets so massive
that in order to escape the gravitational pull,
you have to be moving at the speed of light.
That is the defining property of a black hole.
It's when the escape velocity off the surface of the black
hole is equal to the speed of light, and since
nothing can travel faster than the speed of light
through space, then that is the definition of a black hole.
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>> The University of Texas has been a remarkable place for
black hole measures, and it's a combination of a few things.
It's a combination of the team, we had a couple faculty who
were interested in black holes, that led
to a couple of post-docs being interested,
and that led to a whole team of graduate students.
And so we had this team in place.
We have access to phenomenal facilities
and McDonald Observatory.
From the small telescopes to the biggest telescope, the
10 meter Hobby-Eberly telescope, and then we had access
to the Texas advanced computing
center and that large, super computer.
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>> McDonald Observatory is the darkest site on earth, that
allows us to do studies that you cannot do at other
telescopes, because there are just some studies
where you need the sky brightness
to be as dark as it possibly can.
It's this combination that really
made this whole program sing.
You know, what we're trying to do
is understand how our galaxy forms.
The black hole mass is an essential component of the galaxy,
and so therefore, we need to understand the mass in
terms of the physical relationship to the galaxy.
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>> I'm working on trying to understand
the physical nature of dark energy.
So this is the expansion of the universe and trying
to understand how the universe expands over time.
How I'm doing that is we have a very large experiment where
we're making the largest map ever in the universe, and
from that map, we can then infer how the universe expands
over time, and from that information,
then we infer the nature of dark energy.
This project is called HETDEX, the
Hobby-Eberly Telescope Dark Energy Experiment.
>> My name is Sarah Tuttle [assumed spelling], I'm a
researcher at McDonald Observatory and in the
Astronomy Department at the University of Texas.
I'm the instrument scientist for VIRUS.
VIRUS is the replicated spectograph that we're
installing on HET, to do the HETDEX science.
So VIRUS is all of the hardware beyond the telescope.
This is the part that will take the light, feed optical
fibers, and go down into our instrumentation to
actually measure the galaxies that we're observing.
>> I think the greatest result that we can get is to
have dark energy be something completely unplanned for.
That's the nature of science.
That's the beauty of astronomy, the beauty of discovery is
when you go and find something that is
completely out there and just makes no sense.
That's when the breakthroughs happen.
I want people to take away the big picture of how our
existence on earth can relate to the
whole environment in the universe,
and the whole evolution of the universe itself.
By having us on earth, being able
to comprehend the universe itself.
For me, personally, it gives me a better
appreciation for what goes on on earth.
To understand even though we are insignificant, we can make
these great conceptual understanding of what
the universe is, and if I can grab that,
and if I can make people appreciate that, we can understand
this enormous universe over the billions of years from
our singular location on earth, that is our relevant,
that's what makes us the most relevant
aspect of the universe [music].
