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Narrator: The universe is home
to real monsters.
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We can't see them,
but we know they're out there.
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You really can't get anything
bigger or stronger or scarier
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than a black hole.
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Narrator: Black holes consume
planets and stars --
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anything that gets too close.
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Black holes give physicists
no end of headaches,
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'cause they break all the rules.
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Narrator:
But they rule the universe.
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They are center-stage.
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We now know they dominate
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the evolution
of the universe itself.
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Narrator: Black holes
are the most mysterious objects
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in our universe.
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Their gravity is absolute.
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Nothing can escape.
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They can suck in whole galaxies.
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Black holes
used to be science fiction.
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Now we know they're real.
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When I was a PhD student,
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people used to giggle when
you'd hear about black holes.
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They're like unicorns,
mythical creatures.
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We called this
the "giggle factor."
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People would say,
"Beam me up, Scotty."
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Well, no one is
laughing anymore.
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Krauss:
So, they're not science fiction.
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Even though
we've never landed in one,
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we have enough evidence to know
that they're really out there.
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Narrator: This image might not
look like much to you and me,
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but to a scientist, it's proof
that black holes exist.
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It's an actual movie
of a black hole devouring a star
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in the constellation of Aquila.
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Black holes are messy eaters.
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The red spots you see are gas
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that's being spit
out of the hole, into space.
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Eventually,
over the next million years,
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this star will be eaten alive
and disappear.
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A black hole is pretty much
the end point of everything.
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It's the end point of a star.
It's the end point of matter.
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It's the end point of energy.
It's the end point of gravity.
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I mean, that's really it.
That's the top of the scale.
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Narrator: Although
they have the power to destroy
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like nothing else
in the universe,
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black holes also help build
galaxies --
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a vital part
of the great cosmic machine.
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Some astronomers think
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they could even be gateways
to parallel universes.
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Dr. Kaku: We are now entering
the golden age of research
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in black-hole physics.
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They could be the key
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to understanding
the birth of the universe,
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its formation,
and then its death.
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Dr. Krauss:
Black holes really represent,
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in one sense, the frontier
of modern astronomy.
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And they're changing our ideas
about how galaxies form
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and, indeed,
how the universe works.
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Narrator:
Their power comes
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from one of the primary forces
in nature -- gravity.
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Dr. Kaku:
I teach astronomy.
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And we teach our students
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that the fundamental principle
of gravity is, "gravity sucks."
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Narrator: Gravity keeps our feet
on the ground
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and our planet
orbiting around the Sun.
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But in a black hole, the force
of gravity is off the charts --
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so strong,
it sucks in anything nearby.
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It can even bend
the light from distant stars.
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And if that light
gets too close,
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the black hole swallows it.
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Think of it like this.
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Imagine a black hole
as a waterfall.
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Gravity is the river
flowing toward the falls,
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and a beam of light --
the kayak.
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Upriver from the waterfall,
the current is weak.
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The kayaker can paddle
against it and get away.
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But closer to the waterfall,
the current is stronger,
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and the kayaker struggles
to escape.
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The edge of the waterfall is
like the edge of a black hole.
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No matter how strong
the kayaker is, he's going down.
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It's the same in space.
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The way black holes
are really devastating
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is because
when you get close to them,
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the gravity gets super-strong.
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Narrator:
So strong that they eat light.
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That's why black holes
are black.
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A black hole
is like a roach motel.
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Everything checks in.
Nothing checks out.
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Narrator: Anything
that gets too close is doomed --
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planets, stars,
even whole solar systems.
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And don't think this is
some faraway phenomenon.
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Black holes are on the loose
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right here in our own
cosmic neighborhood.
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We now know there
are wandering nomads
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throughout
the Milky Way galaxy --
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vagabonds throughout the galaxy,
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where black holes can
come up right behind you
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and perhaps gobble you up,
and they won't even burp.
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If one ever comes close,
watch out.
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Narrator: If a black hole found
its way into our solar system,
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it would rip us apart.
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Dr. Plait:
Any kind of black hole
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that could pass
through the solar system
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would be pulling
on all the planets
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harder than the Sun does.
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And so it's just
gonna totally disrupt
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the gravitational balance
of the solar system.
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Narrator: The black hole would literally
tear planets from their orbits
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and smash them into each other.
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It's just an epic disaster.
It's a bull in a china shop.
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If it got close enough
to, say, Jupiter,
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it could actually pull
the moons of Jupiter
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away from the planet itself.
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It would just be flinging
planets left and right
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everywhere as it whipped
through the solar system,
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leaving disaster in its wake.
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Narrator: If a black hole
approached Earth,
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all that gravity would rip
asteroids from their orbits
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and hurl them toward our planet.
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The Earth's surface
would become an inferno.
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It would be
the beginning of the end.
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First, it would swallow up
the atmosphere,
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then the planet itself.
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Destroying
an entire solar system
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is nothing to a black hole.
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But it's more than just a big,
empty, sucking piece of space.
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It's incredibly heavy.
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To get an idea just how heavy
and dense a black hole is,
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imagine the Earth.
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Now start to crush it...
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...and keep crushing
until it's packed so tight
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even the atoms themselves
coHapse.
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When the Earth crushes down
to just 2 inches across,
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that's the density
of a black hole.
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It would be
the size of a golf ball,
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yet weigh the same as the Earth,
with the same amount of gravity.
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What can make
something that small,
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that dense, and that powerful?
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We don't have external forces,
large pistons in the universe,
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to create black holes.
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So the only way the real
black holes of the universe form
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is if gravity
can do the job itself.
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Narrator: There is only
one place in the universe
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that generates
that much gravity.
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And it's
inside the largest stars.
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When massive stars 10 times
heavier than our sun die,
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gravity crushes them,
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creating a huge explosion,
a supernova.
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But some stars
are even bigger than that.
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These supermassive stars weigh
100 times more than our sun
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and have 100 times more gravity.
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When one of these stars dies,
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it sets off the biggest
explosion in the universe...
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A hypernova.
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This is the birth
of a black hole.
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Narrator:
Our universe is full of stars.
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At the end of their lives,
some die quietly.
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Others go out
in spectacular explosions.
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And some give birth
to black holes.
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Dr. Plait:
If you have a star,
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a supermassive star that's
100 times the mass of the Sun,
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at the end of its life,
the core runs out of fuel.
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There's nothing left
to hold it up,
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and the core collapses
down into a black hole.
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Narrator: When that happens,
the enormous gravity
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generated at the heart
of supermassive stars runs wild.
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This is the dying star
V.Y. Canis Majoris.
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It's more than
a billion miles across.
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Like all stars, it's a giant
nuclear-fusion reactor,
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pumping energy outward.
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At the same time, the star's
extreme gravity crushes inward.
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For a few million years,
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fusion and gravity
are locked in standoff.
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But when the star
runs out of fuel,
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fusion stops
and the stalemate ends.
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Gravity wins.
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In a millisecond,
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the core shrinks to a fraction
of its original size
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and a baby black hole is born.
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Immediately,
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it starts to cannibalize
what's left of the star.
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As matter swirls into the black
hole, it gets incredibly hot.
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And there are magnetic forces
and frictional forces,
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and it's just a witch's brew,
a nightmare,
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what's going on right above
the surface of the black hole.
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Narrator:
The new black hole in the middle
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keeps feeding on the body
of the star around it.
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It eats the gas so fast,
it chokes and coughs,
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blasting out
huge beams of energy.
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Dr. Plait: They basically
eat their way out from the star.
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This happens in milliseconds.
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It happens before
the rest of the star even knows
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the core is gone.
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And so basically, the star is
dead before it hits the ground.
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Narrator:
Finally, the star explodes.
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In one second, it blasts out
100 times more energy
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than our sun will produce
over its entire life.
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What's left is a new black hole
and two jets of energy
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hurtling through the universe
at the speed of light.
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00:13:19,833 --> 00:13:23,463
These jets are called
"gamma-ray bursts."
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00:13:28,908 --> 00:13:32,037
Dr. Plait: They're
incredibly energetic events.
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00:13:32,045 --> 00:13:34,377
In terms
of raw energy and power,
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gamma ray bursts are second
only to the Big Bang itself.
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Narrator: Most of them last
only a few seconds.
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And they fry
anything in their way.
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They're so intense that
if there was a gamma-ray burster
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in the region of our galaxy
near our solar system,
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it could literally vaporize
the entire planet.
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Narrator: Fortunately, most gamma-ray
bursts occur outside our galaxy.
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But they tell us
something important
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about black holes
and how our universe works.
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What we were seeing every time
a gamma-ray burst went off
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was basically
the birth cry of a black hole.
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Narrator: By counting gamma-ray
bursts, astronomers can figure out
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how many black holes
are being created.
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In 2004, NASA launched
the Swift probe
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to scan the universe
for gamma-ray bursts.
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Man: Five...
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00:14:42,182 --> 00:14:43,206
four...
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00:14:43,216 --> 00:14:44,240
three...
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00:14:44,250 --> 00:14:45,376
two...
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00:14:45,385 --> 00:14:47,513
one...
We have ignition.
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And we have lift-off
of NASA's Swift spacecraft,
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on a mission to study
and understand gamma-ray bursts
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throughout the universe.
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Narrator: This is the most
powerful gamma-ray burst
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Swift has detected so far.
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The flash of light announces
the birth of a new black hole
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on the other side
of the universe.
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Swift can only look at
a fraction of what's out there.
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Still, it detects at least
one gamma-ray burst every day.
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00:15:33,967 --> 00:15:38,564
That discovery rocked astronomy
to its foundations.
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Dr. Kaku: We once thought
that black holes, like unicorns,
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00:15:43,843 --> 00:15:46,471
could never be found.
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00:15:46,479 --> 00:15:49,881
We now believe that there are
perhaps billions of black holes
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00:15:49,883 --> 00:15:51,180
in the night sky.
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00:15:51,184 --> 00:15:53,881
When we look around our galaxy
and other galaxies,
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00:15:53,887 --> 00:15:58,757
it's clear that the universe
is full of powerful black holes.
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Narrator: Finding black holes
is one thing.
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00:16:01,327 --> 00:16:02,988
Figuring out how they work --
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that's a whole different
ball game.
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00:16:05,165 --> 00:16:07,930
The only way to find out
is to visit one.
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00:16:07,934 --> 00:16:12,337
You'd have to take a spacecraft
across the vastness of space
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just to get close to it.
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Then you'd have to go
inside the black hole.
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There, you'd find a place
245
00:16:20,313 --> 00:16:24,443
where reality breaks down
and time stands still.
246
00:16:28,121 --> 00:16:31,489
Narrator: There are billions
of black holes in the universe.
247
00:16:31,491 --> 00:16:34,859
We can detect them
with telescopes and satellites.
248
00:16:34,861 --> 00:16:39,526
But we don't actually know
what they're like up-close.
249
00:16:39,532 --> 00:16:40,931
It's a long way off,
250
00:16:40,934 --> 00:16:43,562
but scientists
are already speculating
251
00:16:43,570 --> 00:16:46,938
about a mission
to a black hole...
252
00:16:46,940 --> 00:16:51,673
A one-way trip to the most
dangerous place in the universe.
253
00:16:55,415 --> 00:16:56,905
Dr. Kaku:
Originally,
254
00:16:56,916 --> 00:17:01,820
physicists were horrified
at the idea of black holes.
255
00:17:01,821 --> 00:17:03,414
They wanted to banish them,
256
00:17:03,423 --> 00:17:06,154
because the laws of physics,
as we know them,
257
00:17:06,159 --> 00:17:09,117
seem to break down
at the instant of a black hole.
258
00:17:09,128 --> 00:17:10,687
Time stops.
259
00:17:12,131 --> 00:17:14,964
Gravity becomes infinite.
260
00:17:14,968 --> 00:17:18,393
This is a nightmare.
261
00:17:18,404 --> 00:17:21,772
Narrator: Obviously, we can't send
humans anywhere near a black hole.
262
00:17:21,774 --> 00:17:24,505
But a robot?
Well, sure.
263
00:17:24,511 --> 00:17:27,640
A robotic probe
could transmit data back
264
00:17:27,647 --> 00:17:30,378
just before
it goes over the edge.
265
00:17:30,383 --> 00:17:35,378
That edge of a black hole
is called the "event horizon."
266
00:17:35,388 --> 00:17:37,584
It's the edge
of time and space --
267
00:17:37,590 --> 00:17:41,220
at least,
in the universe we know.
268
00:17:41,227 --> 00:17:43,286
We call the event horizon
"event horizon"
269
00:17:43,296 --> 00:17:44,354
quite simply because
270
00:17:44,364 --> 00:17:46,128
it separates space
into two regions.
271
00:17:48,935 --> 00:17:50,403
It's not a physical surface.
272
00:17:50,403 --> 00:17:53,771
You might not even notice it
if you were falling through it,
273
00:17:53,773 --> 00:17:57,038
but ultimately, once you're
inside of it, you're doomed.
274
00:17:57,043 --> 00:17:59,239
Narrator: As you approach
the event horizon,
275
00:17:59,245 --> 00:18:01,009
gravity gets stronger
276
00:18:01,014 --> 00:18:05,110
and very strange things
start to happen.
277
00:18:05,118 --> 00:18:08,315
Dr. Plait: As you fall
into a black hole feet-first,
278
00:18:08,321 --> 00:18:10,847
your feet are closer
to the black hole.
279
00:18:10,857 --> 00:18:14,555
And so the gravity they feel
is stronger.
280
00:18:14,561 --> 00:18:16,359
Your head is not quite as close,
281
00:18:16,362 --> 00:18:18,558
and so the gravity it feels
is less.
282
00:18:18,565 --> 00:18:21,330
And basically, what happens is,
you get stretched out.
283
00:18:21,334 --> 00:18:23,701
Your feet are being pulled
much harder than your head,
284
00:18:23,703 --> 00:18:25,068
and you're like a piece of taffy
285
00:18:25,071 --> 00:18:26,800
being pulled
between two strong people.
286
00:18:29,275 --> 00:18:31,403
As you get thinner
and thinner and thinner,
287
00:18:31,411 --> 00:18:33,436
as you get closer
and closer and closer,
288
00:18:33,446 --> 00:18:37,007
you're undergoing a process
we call "spaghettification"
289
00:18:37,016 --> 00:18:40,987
because you're basically turned
into a long, thin tube of pasta.
290
00:18:44,924 --> 00:18:48,451
Narrator: Gravity would stretch
our robotic probe to the limit,
291
00:18:48,461 --> 00:18:50,156
then rip it apart.
292
00:18:58,805 --> 00:19:01,297
But imagine
if the probe was strong enough
293
00:19:01,307 --> 00:19:03,742
to survive and keep going.
294
00:19:06,679 --> 00:19:12,118
As it gets close to the event
horizon, everything goes crazy.
295
00:19:12,118 --> 00:19:17,682
Gravity is so extreme,
it stops time.
296
00:19:17,690 --> 00:19:20,022
Dr. Kaku: We think of time
as being endless.
297
00:19:20,026 --> 00:19:23,189
However, in a black hole,
in some sense, time stops.
298
00:19:27,467 --> 00:19:30,493
Dr. Plait: This sounds like it's
nuts, but that's the way it works.
299
00:19:30,503 --> 00:19:31,937
It's in the math.
300
00:19:31,938 --> 00:19:36,341
It's actually woven into the
fabric of the universe itself.
301
00:19:36,342 --> 00:19:39,107
Narrator: If you were to watch
from a distance,
302
00:19:39,112 --> 00:19:41,513
the robot probe
would seem to slow down
303
00:19:41,514 --> 00:19:44,040
as it gets closer
to the black hole.
304
00:19:44,050 --> 00:19:47,850
Then it would appear to stop
completely.
305
00:19:47,854 --> 00:19:50,983
The whole process
might just take a brief moment.
306
00:19:50,990 --> 00:19:52,389
But from the outside,
307
00:19:52,392 --> 00:19:56,590
you appear to freeze
and fall ever more slowly.
308
00:19:56,596 --> 00:19:59,293
You actually can never observe
an object fall
309
00:19:59,298 --> 00:20:01,665
all the way
through the event horizon.
310
00:20:01,668 --> 00:20:04,103
It literally freezes
at the surface
311
00:20:04,103 --> 00:20:07,266
because its clock
is going infinitely slowly
312
00:20:07,273 --> 00:20:08,775
compared to yours.
313
00:20:08,775 --> 00:20:13,679
Narrator: In reality,
the probe hasn't stopped at all.
314
00:20:13,680 --> 00:20:17,878
It keeps going
and crosses the event horizon.
315
00:20:19,786 --> 00:20:22,744
If the probe
points its cameras backwards,
316
00:20:22,755 --> 00:20:25,224
towards the entrance
of the black hole,
317
00:20:25,224 --> 00:20:30,890
it will see light
being sucked in.
318
00:20:30,897 --> 00:20:35,960
If it points the camera forward,
at first it sees only black,
319
00:20:35,968 --> 00:20:39,370
but as it moves toward the heart
of the black hole,
320
00:20:39,372 --> 00:20:44,139
it encounters the most bizarre
place in the universe.
321
00:20:45,778 --> 00:20:49,772
The black hole's immense gravity
pulls everything down
322
00:20:49,782 --> 00:20:53,184
to an unimaginably small point
at its center.
323
00:20:53,186 --> 00:20:57,783
Scientists call it
the "singularity."
324
00:20:57,790 --> 00:21:00,282
We really just don't know
325
00:21:00,293 --> 00:21:02,557
what happens
at the center of a black hole.
326
00:21:02,562 --> 00:21:03,859
The densities are so great
327
00:21:03,863 --> 00:21:06,457
that the laws of physics
break down, as we know them.
328
00:21:06,466 --> 00:21:11,233
A singularity is a point
of infinite gravity,
329
00:21:11,237 --> 00:21:14,434
where space and time
become meaningless.
330
00:21:14,440 --> 00:21:16,340
Now, that is ridiculous.
331
00:21:16,342 --> 00:21:21,212
A singularity is basically a
word for saying "I don't know."
332
00:21:21,214 --> 00:21:23,478
It's a word for saying
"I'm clueless."
333
00:21:27,754 --> 00:21:28,949
Narrator: Even now,
334
00:21:28,955 --> 00:21:31,515
scientists can't really answer
the question,
335
00:21:31,524 --> 00:21:32,889
"What is a black hole?"
336
00:21:32,892 --> 00:21:34,485
Dr. Plait:
It's upsetting, a little bit,
337
00:21:34,494 --> 00:21:36,087
to think that there are objects
out there
338
00:21:36,095 --> 00:21:38,496
that are breaking
the laws of physics.
339
00:21:38,498 --> 00:21:40,899
There must be bigger laws
340
00:21:40,900 --> 00:21:42,800
that are being used
by these black holes,
341
00:21:42,802 --> 00:21:44,736
that are being obeyed
by these black holes,
342
00:21:44,737 --> 00:21:46,296
that we just
don't understand yet.
343
00:21:49,809 --> 00:21:52,972
Narrator: Okay, so,
the one thing we do understand
344
00:21:52,979 --> 00:21:56,404
is that black holes are born
from dying stars.
345
00:21:58,551 --> 00:22:02,010
And most are small --
around 20 miles across.
346
00:22:05,358 --> 00:22:08,384
But now
scientists have discovered
347
00:22:08,394 --> 00:22:11,694
that some black holes
are much bigger.
348
00:22:11,697 --> 00:22:14,894
They're called
"supermassive black holes."
349
00:22:14,901 --> 00:22:19,236
They're the same size
as our entire solar system.
350
00:22:19,238 --> 00:22:24,733
And one of these monsters lies
at the heart of our own galaxy.
351
00:22:29,282 --> 00:22:33,708
Narrator: Our solar system lies
in the Milky Way galaxy.
352
00:22:33,719 --> 00:22:38,316
It's made up of billions
of stars, including our sun...
353
00:22:40,626 --> 00:22:43,755
...all revolving
around a mysterious region
354
00:22:43,763 --> 00:22:46,425
right at the center.
355
00:22:46,432 --> 00:22:49,732
Dr. Kaku:
Children ask the question --
356
00:22:49,735 --> 00:22:51,430
if the Moon goes
around the Earth,
357
00:22:51,437 --> 00:22:52,802
the Earth goes around the Sun,
358
00:22:52,805 --> 00:22:54,534
then what does the Sun
go around?
359
00:22:54,540 --> 00:22:56,008
Narrator:
It's a good question.
360
00:22:56,008 --> 00:22:58,375
And astronomers ask
the same thing.
361
00:22:58,377 --> 00:23:00,402
Maybe there was something
going on
362
00:23:00,413 --> 00:23:02,245
at the heart of the Milky Way --
363
00:23:02,248 --> 00:23:07,687
perhaps a black hole
at the very center.
364
00:23:07,687 --> 00:23:11,817
But because we can't
actually see a black hole,
365
00:23:11,824 --> 00:23:16,990
the best they could do
was look for telltale signs.
366
00:23:16,996 --> 00:23:18,725
Using infrared telescopes,
367
00:23:18,731 --> 00:23:21,428
they looked
at the middle of the galaxy
368
00:23:21,434 --> 00:23:24,802
and discovered
a densely packed swarm
369
00:23:24,804 --> 00:23:26,704
of millions of stars.
370
00:23:26,706 --> 00:23:30,574
But they couldn't see
what was at the center.
371
00:23:35,748 --> 00:23:40,242
One team has spent 15 years
looking for clues.
372
00:23:44,924 --> 00:23:48,224
High above the clouds
on Mauna Kea, in Hawaii,
373
00:23:48,227 --> 00:23:51,595
the giant Keck telescope
has the power
374
00:23:51,597 --> 00:23:56,034
to see right through
to the center of the Milky Way.
375
00:24:02,808 --> 00:24:05,505
The region
which we have to study
376
00:24:05,511 --> 00:24:08,879
to prove that there's a
black hole is incredibly small.
377
00:24:08,881 --> 00:24:10,542
It is absolutely the case
378
00:24:10,549 --> 00:24:13,143
of looking
for a needle in a haystack,
379
00:24:13,152 --> 00:24:15,985
except we know
exactly where the needle is.
380
00:24:17,857 --> 00:24:20,986
Narrator: Andrea Ghez
has spent countless nights
381
00:24:20,993 --> 00:24:23,325
scanning
the center of the galaxy
382
00:24:23,329 --> 00:24:25,730
for signs of a black hole.
383
00:24:25,731 --> 00:24:27,597
To be able
to do this experiment,
384
00:24:27,600 --> 00:24:29,034
one has to be able to see
385
00:24:29,035 --> 00:24:31,868
the stars that are very close
to the center of the galaxy
386
00:24:31,871 --> 00:24:34,704
and to position them
incredibly accurately.
387
00:24:34,707 --> 00:24:36,505
And this would be equivalent
388
00:24:36,509 --> 00:24:39,570
to me in Los Angeles
looking at you in New York
389
00:24:39,578 --> 00:24:43,640
and seeing you be able to move
your finger like this.
390
00:24:47,486 --> 00:24:49,750
[motors whirring]
391
00:24:57,496 --> 00:24:59,430
Narrator:
As the Keck kicks into action,
392
00:24:59,432 --> 00:25:03,528
a laser beam detects tiny
disturbances in the atmosphere
393
00:25:03,536 --> 00:25:05,903
that would distort the image.
394
00:25:08,641 --> 00:25:14,569
Motors then adjust the huge
30-foot mirror to compensate.
395
00:25:14,580 --> 00:25:16,810
The image is clear enough
396
00:25:16,816 --> 00:25:20,844
to track the stars
at the heart of our galaxy.
397
00:25:23,189 --> 00:25:27,717
Ghez has taken thousands of
images over the last 15 years.
398
00:25:27,727 --> 00:25:33,325
And what they reveal is amazing.
399
00:25:33,332 --> 00:25:36,063
The stars
at the center of the galaxy
400
00:25:36,068 --> 00:25:38,935
are moving
at millions of miles an hour.
401
00:25:45,411 --> 00:25:49,848
The center of the galaxy
is a very extreme environment.
402
00:25:49,849 --> 00:25:51,806
The speeds with which stars move
403
00:25:51,817 --> 00:25:54,843
is much higher than
anywhere else in our galaxy.
404
00:25:54,854 --> 00:25:57,619
And that is absolutely
the signpost of the black hole.
405
00:26:02,962 --> 00:26:08,867
Narrator: They look like tiny planets
racing around an invisible sun.
406
00:26:08,868 --> 00:26:12,395
But they're not planets.
They're stars.
407
00:26:12,405 --> 00:26:14,464
It takes a lot of gravity
408
00:26:14,473 --> 00:26:18,808
to swing huge stars around
in such fast, tight orbits.
409
00:26:18,811 --> 00:26:23,840
There's only one thing in the
universe with that much pull...
410
00:26:23,849 --> 00:26:28,912
a supermassive black hole.
411
00:26:28,921 --> 00:26:31,185
Watching these things
shows the presence
412
00:26:31,190 --> 00:26:34,057
of a 4-million-times-
the-mass-of-our-sun black hole,
413
00:26:34,060 --> 00:26:36,324
located right at the heart
of our galaxy.
414
00:26:37,997 --> 00:26:40,227
Narrator:
It is a huge discovery.
415
00:26:40,232 --> 00:26:44,066
Everything in our galaxy,
including our own solar system,
416
00:26:44,070 --> 00:26:48,803
orbits around
a supermassive black hole.
417
00:26:48,808 --> 00:26:51,903
But the Milky Way
isn't the only galaxy
418
00:26:51,911 --> 00:26:54,278
with a black hole in the middle.
419
00:26:54,280 --> 00:26:56,510
There are
supermassive black holes
420
00:26:56,515 --> 00:26:59,974
at the heart of most galaxies
in the universe.
421
00:26:59,985 --> 00:27:03,546
The Andromeda galaxy
is our closest neighbor.
422
00:27:03,556 --> 00:27:07,049
It circles around
a supermassive black hole
423
00:27:07,059 --> 00:27:11,826
weighing 140 million times
more than our sun.
424
00:27:11,831 --> 00:27:15,256
Other galaxies,
like this one, M87,
425
00:27:15,267 --> 00:27:21,263
have black holes weighing
as much as 20 billion suns.
426
00:27:21,273 --> 00:27:23,901
How do black holes get so big,
427
00:27:23,909 --> 00:27:28,346
and what are they doing
at the center of galaxies?
428
00:27:28,347 --> 00:27:33,808
For answers, we have to go back
nearly 14 billion years
429
00:27:33,819 --> 00:27:37,813
to the beginning
of the universe.
430
00:27:37,823 --> 00:27:39,552
Back then,
431
00:27:39,558 --> 00:27:44,189
the universe was filled with
clouds of gas from the Big Bang.
432
00:27:44,196 --> 00:27:45,789
In some places,
433
00:27:45,798 --> 00:27:49,632
the gas was thick enough
for millions of stars to form.
434
00:27:54,540 --> 00:27:57,771
Most of these new stars
were supermassive.
435
00:27:57,776 --> 00:27:59,835
They burned hot and fast
436
00:27:59,845 --> 00:28:03,873
and then exploded,
creating lots of black holes.
437
00:28:14,460 --> 00:28:17,293
The early universe
was a wild-and-crazy place
438
00:28:17,296 --> 00:28:19,560
where huge regions of mass
439
00:28:19,565 --> 00:28:20,930
were collapsing
catastrophically,
440
00:28:20,933 --> 00:28:22,264
producing black holes.
441
00:28:22,268 --> 00:28:25,033
And, in fact, the early universe
might have been
442
00:28:25,037 --> 00:28:27,404
full of emerging black holes
everywhere.
443
00:28:30,109 --> 00:28:32,874
Narrator: Gravity pulled
many of them together.
444
00:28:32,878 --> 00:28:35,210
All over the early universe,
445
00:28:35,214 --> 00:28:39,412
they merged, creating
larger and larger black holes.
446
00:28:42,421 --> 00:28:46,221
Over hundreds of millions
of years, each black hole grew,
447
00:28:46,225 --> 00:28:50,662
producing stronger gravity and
pulling in more and more gas.
448
00:28:50,663 --> 00:28:55,260
New stars were born from the
gas, forming primitive galaxies.
449
00:28:57,336 --> 00:29:01,204
But the black hole
kept on sucking in gas,
450
00:29:01,207 --> 00:29:03,073
until it could take no more,
451
00:29:03,075 --> 00:29:07,137
igniting the most powerful
flamethrower in the universe.
452
00:29:21,160 --> 00:29:24,596
Narrator: A young galaxy
is a vast cluster of stars,
453
00:29:24,597 --> 00:29:27,623
stars that formed
from clouds of gas.
454
00:29:32,571 --> 00:29:35,097
At the center of the new galaxy
455
00:29:35,107 --> 00:29:39,567
is a young, supermassive
black hole feeding on the gas,
456
00:29:39,578 --> 00:29:41,569
getting bigger and bigger.
457
00:29:41,580 --> 00:29:42,843
Dr. Plait:
If you can imagine,
458
00:29:42,848 --> 00:29:45,783
when a galaxy is very young
and still forming,
459
00:29:45,784 --> 00:29:48,617
there's a supermassive
black hole forming at the core,
460
00:29:48,621 --> 00:29:50,612
and the gas
is still falling into it
461
00:29:50,623 --> 00:29:52,148
and still forming the galaxy.
462
00:29:52,157 --> 00:29:54,524
Well,
near that central black hole,
463
00:29:54,526 --> 00:29:56,221
things are getting very hot.
464
00:29:56,228 --> 00:29:57,923
That material is heating up.
465
00:29:57,930 --> 00:30:01,560
Narrator: Gas is speeding
into the black hole.
466
00:30:01,567 --> 00:30:04,059
But it overloads,
467
00:30:04,069 --> 00:30:08,802
and there is no room
for all that excess hot gas.
468
00:30:08,807 --> 00:30:13,210
It has nowhere to go but out.
469
00:30:13,212 --> 00:30:18,275
It's blasted into space
in huge jets of energy.
470
00:30:22,921 --> 00:30:26,448
Each jet is 20 times wider
than our solar system
471
00:30:26,458 --> 00:30:30,691
and shoots
clear through the galaxy.
472
00:30:30,696 --> 00:30:36,658
The supermassive black hole
has ignited a quasar.
473
00:30:36,669 --> 00:30:38,433
Quasars are literally
474
00:30:38,437 --> 00:30:40,599
the brightest objects
in the universe.
475
00:30:40,606 --> 00:30:43,667
They're so intense, they can
outshine an entire galaxy.
476
00:30:43,676 --> 00:30:46,509
Narrator:
This is a real photograph
477
00:30:46,512 --> 00:30:50,380
of a real quasar
in the galaxy M87,
478
00:30:50,382 --> 00:30:53,977
50 million light-years away.
479
00:30:57,456 --> 00:31:01,120
Quasars blast away
huge quantities of gas
480
00:31:01,126 --> 00:31:03,060
from the surrounding galaxy...
481
00:31:05,764 --> 00:31:10,292
...the equivalent
of 10 Earths every minute.
482
00:31:13,739 --> 00:31:15,935
Dr. Plait:
When you heat up a gas,
483
00:31:15,941 --> 00:31:18,103
it tends to expand
and it blows outward.
484
00:31:18,110 --> 00:31:20,807
And it's sort of like a wind,
but on a huge scale.
485
00:31:20,813 --> 00:31:22,838
And you get a black-hole wind,
486
00:31:22,848 --> 00:31:25,442
gas blowing out
from the black hole.
487
00:31:25,451 --> 00:31:30,218
Narrator: Black holes suck gas in.
Quasars blow it out.
488
00:31:30,222 --> 00:31:34,853
But eventually there's no gas
left to make stars,
489
00:31:34,860 --> 00:31:36,624
and the galaxy stops growing.
490
00:31:36,628 --> 00:31:39,427
Dr. Plait: So we think
that the eventual size
491
00:31:39,431 --> 00:31:40,990
that a galaxy can achieve
492
00:31:40,999 --> 00:31:43,559
depends on the black hole
in its center.
493
00:31:43,569 --> 00:31:45,094
The two are tied together.
494
00:31:47,072 --> 00:31:51,873
Narrator: With no gas left to feed
on, the quasar jets shrink and die.
495
00:31:53,345 --> 00:31:56,440
What's left
is a supermassive black hole
496
00:31:56,448 --> 00:32:00,851
at the center of the galaxy,
with a whole lot of young stars,
497
00:32:00,853 --> 00:32:04,915
just like our Milky Way
back when it was young.
498
00:32:04,923 --> 00:32:07,654
Dr. Plait: Early on
in the history of the Milky Way,
499
00:32:07,659 --> 00:32:11,061
when it was a young galaxy,
we were probably a quasar.
500
00:32:11,063 --> 00:32:14,556
Probably every big galaxy
was a quasar when it was young.
501
00:32:14,566 --> 00:32:16,125
But right now we're old enough
502
00:32:16,135 --> 00:32:18,092
that the galaxy
has quieted down.
503
00:32:19,872 --> 00:32:23,809
Narrator: Now astronomers
are looking for quasars,
504
00:32:23,809 --> 00:32:27,211
the secret
to finding more black holes
505
00:32:27,212 --> 00:32:29,840
and figuring out how they work.
506
00:32:29,848 --> 00:32:33,284
The Chandra observatory
is a space telescope
507
00:32:33,285 --> 00:32:39,054
that can detect the powerful
x-rays quasars send out.
508
00:32:39,057 --> 00:32:41,958
It's found thousands.
509
00:32:41,960 --> 00:32:44,486
These remarkable images show
510
00:32:44,496 --> 00:32:49,400
quasars of all shapes and sizes
firing out into space.
511
00:32:53,472 --> 00:32:55,668
Each one is a signpost
512
00:32:55,674 --> 00:32:59,702
for a young galaxy with
a new black hole at its center.
513
00:33:03,549 --> 00:33:06,610
These quasars
will eventually calm down
514
00:33:06,618 --> 00:33:11,954
as their galaxy matures
and takes its final shape.
515
00:33:11,957 --> 00:33:13,891
I guess the universe
is a lot like people --
516
00:33:13,892 --> 00:33:15,326
active when they're young,
517
00:33:15,327 --> 00:33:17,659
a little bit quieter and more
relaxed when they get older.
518
00:33:19,865 --> 00:33:22,891
Narrator: We now know
that supermassive black holes
519
00:33:22,901 --> 00:33:26,963
and the quasars they create
control galaxies.
520
00:33:26,972 --> 00:33:31,000
Dr. Ghez: Black holes are central
to understanding how galaxies form.
521
00:33:31,009 --> 00:33:34,035
They're a key to understanding
how they evolve with time.
522
00:33:34,046 --> 00:33:36,447
So, in fact,
rather than being obscura,
523
00:33:36,448 --> 00:33:38,507
they're fundamental
to our understanding
524
00:33:38,517 --> 00:33:40,315
of our galaxies
and our universe.
525
00:33:40,319 --> 00:33:44,586
Narrator: The only way to
find out more about black holes
526
00:33:44,590 --> 00:33:46,615
is to get a good look at one.
527
00:33:46,625 --> 00:33:50,425
And since an up-close visit
is, well, not a good idea,
528
00:33:50,429 --> 00:33:53,387
astronomers are trying to devise
a way to take a picture
529
00:33:53,398 --> 00:33:57,266
of the supermassive black hole
at the heart of our own galaxy.
530
00:33:57,269 --> 00:33:58,759
To get it,
531
00:33:58,770 --> 00:34:02,900
they'll need a telescope
as large as Earth itself.
532
00:34:13,852 --> 00:34:16,981
[high-pitched whir]
533
00:34:16,989 --> 00:34:18,980
Narrator: There's
a supermassive black hole
534
00:34:18,991 --> 00:34:22,484
at the center of the Milky Way.
535
00:34:24,830 --> 00:34:27,788
It's hidden
by a dense cluster of stars
536
00:34:27,799 --> 00:34:30,291
circling
the heart of the galaxy.
537
00:34:33,138 --> 00:34:37,632
But soon,
we hope we'll be able to see it.
538
00:34:37,643 --> 00:34:41,068
Dr. Kaku:
Seeing is believing.
539
00:34:41,079 --> 00:34:44,310
It would be spectacular
if we can go right up there,
540
00:34:44,316 --> 00:34:47,217
nose-to-nose
with the event horizon
541
00:34:47,219 --> 00:34:50,621
of the black hole at the center
of the Milky Way galaxy.
542
00:34:50,622 --> 00:34:53,922
And that's the Holy Grail.
543
00:34:53,926 --> 00:34:57,226
Narrator: A supermassive
black hole lies hidden
544
00:34:57,229 --> 00:34:59,323
at the center of most galaxies.
545
00:34:59,331 --> 00:35:01,129
We only know they're there
546
00:35:01,133 --> 00:35:04,091
because the stars around them
are drawn in
547
00:35:04,102 --> 00:35:06,332
at millions of miles per hour.
548
00:35:06,338 --> 00:35:08,033
But there might still be a way
549
00:35:08,040 --> 00:35:11,601
to take a picture of the
very edge of the black hole --
550
00:35:11,610 --> 00:35:13,840
the event horizon.
551
00:35:13,845 --> 00:35:17,645
Shep Doeleman and his team
are trying to capture an image
552
00:35:17,649 --> 00:35:19,708
that shows its outline.
553
00:35:19,718 --> 00:35:21,982
We're essentially looking
for the shadow,
554
00:35:21,987 --> 00:35:24,046
or the silhouette,
of the black hole,
555
00:35:24,056 --> 00:35:27,549
within this cloud of gas
that's swirling around it.
556
00:35:27,559 --> 00:35:31,291
This technique
that we're exploiting
557
00:35:31,296 --> 00:35:34,322
is the best hope I think we have
558
00:35:34,333 --> 00:35:37,132
to actually image
a region of the universe
559
00:35:37,135 --> 00:35:40,537
which has hitherto been
completely invisible to us.
560
00:35:40,539 --> 00:35:42,837
Narrator:
Optical telescopes
561
00:35:42,841 --> 00:35:46,368
can't see the black hole
directly.
562
00:35:46,378 --> 00:35:50,246
But the glowing, super-heated
gas surrounding the black hole
563
00:35:50,248 --> 00:35:53,718
sends out radio waves that can
be used to make an image.
564
00:35:55,787 --> 00:36:01,123
Huge radio telescopes pick up
these signals from space.
565
00:36:01,126 --> 00:36:03,618
The antenna will move
in azimuth and elevation.
566
00:36:03,629 --> 00:36:05,961
[beeping]
567
00:36:05,964 --> 00:36:08,433
[whirring]
568
00:36:10,202 --> 00:36:13,968
Narrator: This one, at the
M.l.T. Observatory near Boston,
569
00:36:13,972 --> 00:36:16,703
is more than 100 feet wide.
570
00:36:16,708 --> 00:36:20,838
It's big enough to detect
very faint radio emissions
571
00:36:20,846 --> 00:36:25,807
from the black hole in our own
galaxy, 25,000 light-years away.
572
00:36:25,817 --> 00:36:30,118
But it's not nearly big enough
to capture an image.
573
00:36:30,122 --> 00:36:33,649
We need to take multiple copies
of these telescopes,
574
00:36:33,659 --> 00:36:35,525
place them around the world
575
00:36:35,527 --> 00:36:40,124
to create a virtual telescope
as large as the Earth itself.
576
00:36:40,132 --> 00:36:43,090
Narrator: Doeleman's team
will link up radio telescopes
577
00:36:43,101 --> 00:36:47,265
around the globe,
from Hawaii to Chile to Africa.
578
00:36:53,478 --> 00:36:56,140
When the whole network
is connected,
579
00:36:56,148 --> 00:37:00,244
they'll have a virtual dish
over 10,000 miles across,
580
00:37:00,252 --> 00:37:04,814
with 500 times the power
of a single telescope.
581
00:37:08,260 --> 00:37:10,820
They think
it will be powerful enough
582
00:37:10,829 --> 00:37:13,457
to take a picture
of the event horizon
583
00:37:13,465 --> 00:37:18,960
of the supermassive black hole
at the center of the Milky Way.
584
00:37:18,970 --> 00:37:21,439
They're already picking up
signals
585
00:37:21,440 --> 00:37:23,966
from the dark heart
of our galaxy.
586
00:37:23,975 --> 00:37:26,535
Dr. Doeleman:
When we saw the first detection,
587
00:37:26,545 --> 00:37:29,276
it was a moment where I just
looked at the computer screen
588
00:37:29,281 --> 00:37:32,046
and said to myself,
"My God, we've done it.
589
00:37:32,050 --> 00:37:34,985
We've actually seen something
that's so small
590
00:37:34,986 --> 00:37:37,478
that it has to be coming from
right around the event horizon."
591
00:37:39,057 --> 00:37:42,584
Narrator: The signals are still too
weak to give a complete picture,
592
00:37:42,594 --> 00:37:46,292
but Doeleman expects
the images to improve
593
00:37:46,298 --> 00:37:51,259
as more telescopes come online
over the next few years.
594
00:37:51,269 --> 00:37:56,503
Eventually, the outline of the
black hole itself should emerge.
595
00:37:59,144 --> 00:38:04,310
But even a picture can't compare
to witnessing it for yourself.
596
00:38:06,618 --> 00:38:10,020
In the distant future,
we may have the technology
597
00:38:10,021 --> 00:38:14,492
to actually enter
and pass through a black hole
598
00:38:14,493 --> 00:38:17,554
and maybe even
survive the journey.
599
00:38:23,168 --> 00:38:26,536
Then we might finally answer
the question --
600
00:38:26,538 --> 00:38:30,509
what lies
at the heart of a black hole?
601
00:38:32,677 --> 00:38:34,111
Some scientists believe
602
00:38:34,112 --> 00:38:36,877
we could use black holes
as a kind of portal,
603
00:38:36,882 --> 00:38:40,182
with the potential
for travel across the universe.
604
00:38:40,185 --> 00:38:42,984
Dr. Kaku:
This is still very speculative,
605
00:38:42,988 --> 00:38:45,480
but the mathematics
seem to indicate
606
00:38:45,490 --> 00:38:47,822
that as you fall
through a black hole
607
00:38:47,826 --> 00:38:49,487
that you don't simply die --
608
00:38:49,494 --> 00:38:52,191
you fall
right through a wormhole,
609
00:38:52,197 --> 00:38:56,896
which is a gateway, a shortcut
through space and time.
610
00:38:56,902 --> 00:39:00,566
Perhaps we could simply
rocket across the universe
611
00:39:00,572 --> 00:39:05,908
through a subway system
that we call a black hole.
612
00:39:05,911 --> 00:39:10,212
Narrator: If black holes are
shortcuts through space and time,
613
00:39:10,215 --> 00:39:14,243
it could turn one of the coolest
ideas from science fiction
614
00:39:14,252 --> 00:39:17,984
into reality.
615
00:39:17,989 --> 00:39:21,550
Time travel is possible,
but not very practical.
616
00:39:21,560 --> 00:39:25,121
You see, the energy source,
the material that you need
617
00:39:25,130 --> 00:39:27,656
to keep the throat
of a wormhole open
618
00:39:27,666 --> 00:39:29,134
is something so exotic
619
00:39:29,134 --> 00:39:32,035
that we cannot produce it
in the laboratory.
620
00:39:32,037 --> 00:39:34,995
But if you could,
it might be possible
621
00:39:35,006 --> 00:39:39,136
to exploit the power of
black holes to visit yesterday.
622
00:39:40,779 --> 00:39:43,544
Perhaps our descendants
in the future
623
00:39:43,548 --> 00:39:46,381
have already mastered
this technology.
624
00:39:46,384 --> 00:39:48,580
So one day,
if somebody knocks on your door
625
00:39:48,587 --> 00:39:49,986
and claims to be
626
00:39:49,988 --> 00:39:52,423
your great-great-great-great-
great-great granddaughter,
627
00:39:52,424 --> 00:39:53,414
don't slam the door.
628
00:39:57,462 --> 00:40:01,831
Narrator: Black holes might even
be gateways to other universes.
629
00:40:01,833 --> 00:40:04,393
On the other side
of a black hole,
630
00:40:04,402 --> 00:40:07,394
there could even be...
a Big Bang.
631
00:40:10,709 --> 00:40:14,373
As a black hole collapses
and matter falls into it,
632
00:40:14,379 --> 00:40:17,838
perhaps the matter is blown out
the other side in a white hole.
633
00:40:17,849 --> 00:40:20,011
Doesn't that sound
like the Big Bang?
634
00:40:25,690 --> 00:40:29,354
Narrator: if a Big Bang is just
the flip side of a black hole,
635
00:40:29,361 --> 00:40:33,355
this could be
how our own universe was born.
636
00:40:35,166 --> 00:40:37,692
If you look at the equations
for a black hole
637
00:40:37,702 --> 00:40:39,602
and put in the parameters
of the universe --
638
00:40:39,604 --> 00:40:41,834
the mass of the universe,
the size of the universe --
639
00:40:41,840 --> 00:40:42,898
bingo!
640
00:40:42,908 --> 00:40:44,342
You find that our universe
641
00:40:44,342 --> 00:40:46,970
actually solves the equations
for a black hole.
642
00:40:46,978 --> 00:40:50,209
In other words, we could be
inside an event horizon.
643
00:40:50,215 --> 00:40:55,710
Perhaps we are actually living
inside a black hole.
644
00:40:55,720 --> 00:40:59,179
Narrator: Every black hole
might be the origin
645
00:40:59,190 --> 00:41:02,057
of an entirely separate
universe.
646
00:41:02,060 --> 00:41:03,425
If that's true,
647
00:41:03,428 --> 00:41:08,025
there could be billions
of universes out there...
648
00:41:11,503 --> 00:41:16,771
...each one
full of stars, planets, life.
649
00:41:16,775 --> 00:41:19,301
Whatever we figure out later,
650
00:41:19,311 --> 00:41:23,270
we know now
that black holes are everywhere.
651
00:41:23,281 --> 00:41:24,510
They're bigger in size
652
00:41:24,516 --> 00:41:27,247
and more critical
to the evolution of the universe
653
00:41:27,252 --> 00:41:29,380
than we ever imagined.
654
00:41:40,765 --> 00:41:42,699
Dr. Krauss:
Literally, our understanding
655
00:41:42,701 --> 00:41:44,760
of the universe
that's important around us,
656
00:41:44,769 --> 00:41:47,170
the universe
that's visible to telescopes,
657
00:41:47,172 --> 00:41:49,038
has been profoundly affected
658
00:41:49,040 --> 00:41:52,408
by our realization
that black holes are everywhere.
659
00:41:55,380 --> 00:41:56,643
Dr. Kaku:
Once upon a time,
660
00:41:56,648 --> 00:41:58,309
people thought
that black-hole physics
661
00:41:58,316 --> 00:42:01,479
was too fantastic to be true.
662
00:42:01,486 --> 00:42:04,114
And now they are center-stage.
663
00:42:04,122 --> 00:42:05,590
We now know they dominate
664
00:42:05,590 --> 00:42:07,786
the evolution
of the universe itself.
665
00:42:09,761 --> 00:42:11,126
Dr. Plait:
When I was a kid,
666
00:42:11,129 --> 00:42:13,427
black holes basically played
a part in science fiction.
667
00:42:13,431 --> 00:42:14,956
It was always
something to avoid.
668
00:42:14,966 --> 00:42:16,195
Your spaceship --
669
00:42:16,201 --> 00:42:18,158
you try to get around them
before you get drawn in.
670
00:42:18,169 --> 00:42:20,228
But what we've learned
since then
671
00:42:20,238 --> 00:42:22,468
is that black holes
play a huge role
672
00:42:22,474 --> 00:42:24,966
and a huge number of roles
in the universe.
673
00:42:27,912 --> 00:42:30,244
It's not an exaggeration
to say
674
00:42:30,248 --> 00:42:34,014
that if black holes did not
exist, we wouldn't be here.
675
00:42:34,019 --> 00:42:36,750
We literally owe
our existence to black holes.
676
00:42:40,925 --> 00:42:44,361
Narrator:
The story's not over yet.
677
00:42:44,362 --> 00:42:46,990
There's still
much more to be discovered
678
00:42:46,998 --> 00:42:51,936
about the mysterious objects
called black holes...
679
00:42:51,936 --> 00:42:55,133
The masters of the universe.
55302
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