How the Universe Works
Season 6
TV Series | How the Universe Works | Contents page
How the Universe Works S06E01
Part 1
Dec. 22, 2021, 7:22 p.m.
Cosmologists are battling over
the universe's greatest enigma.
Black holes.
We've never seen them.
It's near impossible
to study them.
And their existence
challenges everything
we think we know about space.
The black hole represents
the absolute limits
of what we understand
about nature.
The truth is, we have almost
no idea what these things are
and how they work.
Black holes are at
the very heart of cosmology.
Yet, some scientists question
if they're even real.
Black holes present
lots of paradoxes,
and the simplest way to resolve
the paradoxes would be
if black holes
didn't exist at all.
Solving the mysteries
of black holes
pushes our understanding
of physics
to the edge of reason.
But it's the only way
to discover
if black holes really exist.
Black holes are the monsters
of the universe...
Terrifying cosmic beasts
that devour all they encounter.
But black holes scare scientists
for very different reasons.
They challenge our theories
to the breaking point.
This is at the forefront
of theoretical physics.
When it comes to the
detailed nature of black holes,
it would not surprise me
if we got it all wrong.
The science of black holes
is so challenging
that some scientists question
whether they exist at all.
Despite their fearsome
reputation,
we've never actually seen one.
Black holes are everywhere.
They're all over the universe.
They're all throughout
our galaxy.
But that doesn't mean
that they're easy to find.
They're black,
and space is black,
and black-on-black
is kind of hard
to see in a picture of space.
This is paradoxical
because scientists believe
black holes are born
in some of the brightest
explosions in the universe...
rising from the corpses
of detonated stars
many times larger than our sun.
A star that burns
for 10 million years
collapses to form a black hole
in a period of seconds.
As it collapses,
the outer region of the star
hits the core,
triggering a huge explosion...
A supernova.
We see the bang,
but not what's left behind...
a dead core with
the enormous mass of the star
crushed down into
an infinitesimal, tiny area.
From this minuscule
high-mass core,
a black hole is born.
The flow of gravity is so strong
that nothing can escape...
Not even light.
But how can scientists claim
that black holes exist
if we can't even see them?
You could say that about
the existence of the atom.
We knew they had existed
for decades, centuries
before we had actually seen one
in some sort of imaging device.
And so it's the same sort
of thing with black holes.
Just because you can't see it
doesn't mean it's not there.
Not seeing black holes
but knowing they're there
is a possibility,
just like we know
that wind is there,
even though we can't see air.
Air is invisible,
but when the wind blows,
its effects can be measured.
It's the same with black holes.
You just need to know
what to look for.
While they emit
no light themselves,
black holes are tremendous
sources of x-rays,
and that's because as things
get close to a black hole,
they're accelerated
by the gravity,
and they can heat up
to millions of degrees.
Million-degree gas
gives you lots of x-rays.
To find and measure
these telltale x-rays,
scientists turn
to the NuSTAR space telescope.
In 2017, it spots
a burst of x-rays
in a cluster called 47 Tucanae,
at the edge of the milky way.
When scientists analyze
the data,
they realize they're
looking at two objects
orbiting each other
very closely.
All we see is that there's
a star being ripped apart,
and gas is spiraling down to
a very dense, very dark object,
so something weird is going on.
As one of the objects
accretes matter off the other,
it causes it to emit x-rays,
How the Universe Works
Season 6
TV Series | How the Universe Works | Contents page