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Viewers like you make
this program possible.
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Support your local PBS station.
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Something
is hiding in the darkness.
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00:00:16,947 --> 00:00:20,192
Invisible objects
of unimaginable power
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that could hold the key to
solving the mysteries of space,
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time, and the universe itself.
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To me, a black hole is
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the greatest exhibition
of nature's mysterious powers.
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You literally can't see them.
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And that's what makes them
extremely mysterious.
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They are
bizarre quirks of nature.
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When we're studying black holes,
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we're right on the edge
of human knowledge.
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And yet, they
are sculptors of the cosmos.
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The jets from black
holes are so powerful, they can affect
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the whole shape and nature
of a galaxy.
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Even shaping
our own galaxy, the Milky Way.
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We had hints that black holes
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were at the center of all
of galaxies, like our own.
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Can we lift the veil...
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Forget the one-way trip to Mars.
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I'm going in the black hole.
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And reveal their secrets?
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Fermi revealed something
completely astonishing
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and unexpected.
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We've never seen anything
like it.
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Finding these little pieces
of the puzzle that did not fit
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is super-exciting.
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But
if you really want to understand
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the deepest questions
of the universe,
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you have to understand
black holes.
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"Black Holes,"
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right now, on "NOVA."
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As we gaze out at the Milky Way,
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our eyes are drawn to the light.
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Hundreds of billions of stars
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serenely spinning through
the cosmos.
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When we
look up at the night sky,
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00:02:45,372 --> 00:02:48,789
the stars and planets that
we see are beautiful.
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But actually,
it's in the space between these,
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in the dark patches,
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00:02:52,724 --> 00:02:56,141
that some of the most
fascinating things lie.
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00:02:59,558 --> 00:03:02,216
In places
where there is no light,
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00:03:02,251 --> 00:03:08,326
objects of profound mystery
bide their time.
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00:03:08,360 --> 00:03:12,537
Awesome in their simplicity
and perfection,
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we call them black holes.
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00:03:15,919 --> 00:03:17,266
A black hole
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is an infinitely dense point
in space from which nothing
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can escape, not even light.
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It's extraordinary to think
that black holes are everywhere
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in the universe,
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that they have existed from very
early times in the universe.
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When quiet, they
are almost impossible to detect.
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We're talking about a region of space
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where, if something falls in,
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we'll never know about it
ever again.
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They hold the
power to shred stars and worlds,
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but also, the potential to shape
galaxies...
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Black holes are one of the most
fundamentally important
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singular objects that might
dictate how galaxies
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form and evolve.
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It's natural to fear them,
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but we're learning that
they're essential.
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You can't live with them,
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but you also can't live without
them.
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And they may
hold the secret to the ultimate fate
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of the universe.
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Black holes,
on a fundamental level,
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challenge our understanding
of physics,
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of the way that everything
in the universe works.
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Black holes are the most
mysterious objects
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in the universe, full stop.
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To understand black
holes, we have to start at the beginning.
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At the moment of birth.
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Black holes
that are a few times the mass of the sun
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probably formed from giant stars
that were maybe about
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20 to 30 times
the mass of the sun.
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Enormous stars
burning bright blue with intense heat.
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But the brightest stars
are the shortest-lived.
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A star is
a big ball of gas, right?
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There's outward gravity
pushing in, right?
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The thing wants to collapse
in on itself
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under its own self-gravity.
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But the fusion that's happening
within the star's core
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liberates so much light that
the outward radiation pressure
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prevents the collapse
of that star.
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But eventually, that gives up.
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A star like that
can burn through its nuclear fuel
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in just a few million years.
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And when its power source runs
out,
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it collapses under its own
gravitational pull.
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There's so much material
that's collapsing during
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their final few moments
that they create this massive
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dense ball of neutrons
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that continues to collapse.
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A star 20 times
the mass of our sun or larger...
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crushed by the force of gravity,
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until the star disappears,
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leaving only a ghost behind.
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A black hole.
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This transformation does not
await all stars.
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Smaller, less massive stars,
like our sun,
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eventually become burnt-out
dwarves when their fusion stops:
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slowly fading cinders.
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But it's possible that almost
all the massive stars
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that dominated the early
universe formed black holes
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when they died.
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Because black holes are simply
what happens when enough matter
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is crushed into a small enough
volume,
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dramatically warping the space
around it.
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A river is a
great analogy for the area right around
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a black hole.
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Here I am far upstream,
and the water is fairly placid.
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It's not moving too fast.
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If I were to get into the water
here and swim across,
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I'd be able to do that
very easily.
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In the same way, if you're
far away from a black hole,
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you'll be able to get around
with just a normal spacecraft
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without too much trouble
and simple propulsion.
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But the closer
you get to the black hole,
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the stranger things become.
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The collapsed massive star
crushes down
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so small and so dense,
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it ceases to have a physical
surface at all,
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becoming an infinitely small
point in space,
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exerting a profound effect
on the space-time around it.
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As the water
gets closer to the waterfall,
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the speed of the water
increases.
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If I were to jump into the water
right here,
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the speed of the current
would be so intense
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that I wouldn't be able to swim
against it,
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and I would be gradually pulled
closer to the edge
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of the waterfall till I reach
a point of no return.
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And that's the same around
a black hole.
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Just outside the
black hole, the fabric of space itself
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actually stretches inward
towards the center.
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Not even stars, planets,
people, even light cannot escape
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00:09:08,789 --> 00:09:10,515
the pull of a black hole.
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It's like a waterfall
in the fabric of the universe.
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The black hole's
gravitational reach is not infinite.
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People have
this idea that black holes suck,
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in the sense that they suck
everything into them,
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but that's not true.
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Black holes can only eat things
that are within
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a certain distance away
from them.
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If you're further away,
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then the black hole has no way
of eating you.
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But once in
its grasp, you are lost forever.
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And this is the key
to their mystery.
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The black hole's interior
is hidden from view,
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cut off from the rest of the
universe by a boundary in space:
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the event horizon.
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Beyond this point,
there is no escape.
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As we approach
the event horizon,
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we get our first glimpse of the
true weirdness of black holes.
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Ever since Einstein,
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we've viewed the fabric of the
universe
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not as something static, but
instead something that's fluid,
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something that bends and warps
around objects with mass.
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We call this space-time,
a combination of space and time.
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See, Einstein's insight was to
realize that these two things
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are intimately connected.
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That when an object has mass,
it not just bends space,
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but changes the passage of time
itself.
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In particular, the effect of a
mass is to slow time down.
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In the region
around the black hole,
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the warped space-time
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elongates light waves,
distorting color.
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The event horizon is the place
at which time stops
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when seen from far away.
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Someone who's outside
the black hole will see you get
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redder and redder...
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And your time will slow down.
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And you'll kind of pass through
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the horizon, disappear forever.
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Black holes are like
waterfalls in the fabric of the universe,
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where space contorts and time
itself grinds to a halt,
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ensnaring light,
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making them lockboxes for the
universe's ultimate secrets.
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00:12:39,482 --> 00:12:43,693
It is said that
fact is sometimes stranger than fiction,
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and nowhere is that more true
than in the case of black holes.
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Black holes are stranger
than anything dreamed up
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by science fiction writers,
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but they are firmly matters
of science fact.
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The vast majority
of black holes are small...
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less than 20 miles across...
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and they usually wander alone
through space.
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But if we turn our gaze towards
the center of the Milky Way
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and journey inwards,
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through the gas and dust
that shroud the galactic core,
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signs of something altogether
different appear.
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If you simply observe
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the stars in the very heart of
our galaxy over about 20 years,
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you will observe them orbiting
nothing.
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At the center of this swarm of
stars is darkness.
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It's a void.
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00:13:50,105 --> 00:13:55,524
Scientists name this
invisible enigma Sagittarius A-star,
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00:13:55,558 --> 00:13:58,838
although it is not a star
at all.
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Can you imagine
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how massive that object
has to be to be able to pull
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entire stars into orbit?
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00:14:07,985 --> 00:14:10,056
They
believe it to be a black hole
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more than four million times
the mass of our sun...
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00:14:14,301 --> 00:14:15,924
many thousands of times
more massive
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than any other in the Milky Way.
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00:14:19,065 --> 00:14:20,238
How did this monster
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come to live at the heart
of the Milky Way?
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00:14:22,758 --> 00:14:28,419
Sagittarius
A-star is a supermassive giant
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around which the entire galaxy
spins,
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00:14:32,733 --> 00:14:36,910
raising intriguing new questions
about the role of black holes
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00:14:36,945 --> 00:14:40,569
in our galaxy and the universe.
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00:14:40,603 --> 00:14:42,536
How did it get there?
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00:14:42,571 --> 00:14:45,436
How did it get so big?
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00:14:45,470 --> 00:14:48,508
And what can it tell us
about how black holes
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00:14:48,542 --> 00:14:50,924
shape the cosmos?
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00:14:50,959 --> 00:14:52,615
Would we even be here today
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00:14:52,650 --> 00:14:54,376
without Sagittarius A-star?
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00:14:59,864 --> 00:15:01,866
Just a few minutes
away from the 26th flight
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00:15:01,901 --> 00:15:03,178
of the shuttle Columbia,
220
00:15:03,212 --> 00:15:04,938
with a crew of five.
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00:15:11,669 --> 00:15:14,948
I think a
night launch is particularly exciting.
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00:15:14,983 --> 00:15:17,847
Go for engine start.
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00:15:17,882 --> 00:15:21,541
We have booster ignition
and lift-off of Columbia.
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00:15:21,575 --> 00:15:23,923
Roger roll,
Columbia, we're looking in.
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00:15:25,545 --> 00:15:27,961
Chandra is huge.
226
00:15:27,996 --> 00:15:29,376
It's about the size of
a school bus.
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00:15:29,411 --> 00:15:30,860
It's the largest telescope
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00:15:30,895 --> 00:15:33,622
to ever be launched
by the space shuttle.
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00:15:37,350 --> 00:15:41,112
SRB separation is confirmed.
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00:15:41,147 --> 00:15:42,907
You're stressed about
the astronauts onboard
231
00:15:42,942 --> 00:15:45,461
that are literally risking
their lives to help us
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00:15:45,496 --> 00:15:48,119
get a better view
of the universe.
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00:15:52,537 --> 00:15:55,747
In the summer of 1999,
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00:15:55,782 --> 00:15:59,234
NASA's flagship telescope
for X-ray astronomy
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00:15:59,268 --> 00:16:03,410
sets off from the space shuttle
cargo bay.
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00:16:08,070 --> 00:16:10,762
Even two decades
into its voyage of discovery,
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00:16:10,797 --> 00:16:14,594
Chandra remains by far
the most powerful observatory
238
00:16:14,628 --> 00:16:17,217
that we have to observe
the high-energy universe.
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00:16:21,946 --> 00:16:26,675
Almost 83,000
miles above the Earth's surface,
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00:16:26,709 --> 00:16:32,163
at its highest orbit,
Chandra scans the sky
241
00:16:32,198 --> 00:16:35,339
with eight high-precision
mirrors engineered
242
00:16:35,373 --> 00:16:40,102
to detect X-rays emitted
from extremely hot regions
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00:16:40,137 --> 00:16:41,586
of the universe.
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00:16:43,588 --> 00:16:49,146
For 14 years, it searches
among the exploding stars
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00:16:49,180 --> 00:16:52,287
and clusters of galaxies.
246
00:16:54,841 --> 00:16:59,156
But then, on September 14, 2013,
247
00:16:59,190 --> 00:17:04,609
Chandra chances on something
else entirely.
248
00:17:04,644 --> 00:17:06,715
Chandra
wasn't looking for this at all...
249
00:17:06,749 --> 00:17:08,717
just happened to be looking
nearby.
250
00:17:08,751 --> 00:17:10,408
So it was a total surprise.
251
00:17:15,551 --> 00:17:20,418
As the telescope gazes
into the constellation of Sagittarius,
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00:17:20,453 --> 00:17:24,491
it aims to observe a large cloud
of hot gas.
253
00:17:24,526 --> 00:17:28,633
But unexpectedly,
254
00:17:28,668 --> 00:17:33,707
it records a flash of X-rays
just a few pixels across
255
00:17:33,742 --> 00:17:40,231
coming from the seemingly empty
space in the galactic core.
256
00:17:48,688 --> 00:17:50,931
When we see something
get very hot for a very short period
257
00:17:50,966 --> 00:17:53,417
of time, we get very excited.
258
00:17:53,451 --> 00:17:56,282
Something is causing it...
something we can't see.
259
00:18:04,600 --> 00:18:08,777
Some scientists
believe the flash seen by Chandra
260
00:18:08,811 --> 00:18:11,745
is caused by an asteroid...
261
00:18:17,786 --> 00:18:21,307
ripped apart and burning up
in a blaze
262
00:18:21,341 --> 00:18:25,897
hundreds of times brighter
than the sun,
263
00:18:25,932 --> 00:18:30,419
releasing a burst of X-rays
that Chandra can detect
264
00:18:30,454 --> 00:18:35,010
almost 26,000 light-years away.
265
00:18:35,044 --> 00:18:37,771
If we see a level of X-rays
being produced that's so bright,
266
00:18:37,806 --> 00:18:39,118
it can't be explained
267
00:18:39,152 --> 00:18:41,913
by any other process,
then we know that there must be
268
00:18:41,948 --> 00:18:43,812
a black hole there.
269
00:18:43,846 --> 00:18:47,574
It's the behemoth
at the center of our galaxy.
270
00:18:51,026 --> 00:18:53,960
Sagittarius A-star.
271
00:19:02,417 --> 00:19:05,834
You can take a telescope
like Chandra and watch a black hole
272
00:19:05,868 --> 00:19:07,387
have a small snack,
273
00:19:07,422 --> 00:19:10,114
maybe like a human might have a
little biscuit in the afternoon.
274
00:19:10,149 --> 00:19:12,427
And it's something like
an asteroid.
275
00:19:12,461 --> 00:19:14,601
And there will be a small
sort of X-ray signature
276
00:19:14,636 --> 00:19:15,637
from that event.
277
00:19:15,671 --> 00:19:16,914
So it's incredible
278
00:19:16,948 --> 00:19:19,813
that we can actually observe
Sagittarius A-star,
279
00:19:19,848 --> 00:19:22,506
which lies 26,000 light-years
away,
280
00:19:22,540 --> 00:19:26,889
actually eating something.
281
00:19:26,924 --> 00:19:29,098
But Chandra
does not only look inwards.
282
00:19:29,133 --> 00:19:34,690
It also looks out,
beyond the Milky Way.
283
00:19:34,725 --> 00:19:39,661
At the center of almost every
large galaxy Chandra peers into,
284
00:19:39,695 --> 00:19:44,666
it finds evidence that our
galaxy is hardly unusual.
285
00:19:44,700 --> 00:19:46,978
We started to spot
286
00:19:47,013 --> 00:19:49,912
X-ray sources of light
everywhere around the sky,
287
00:19:49,947 --> 00:19:52,743
and we started to realize
something weird was going on
288
00:19:52,777 --> 00:19:54,400
in the centers of galaxies.
289
00:19:57,299 --> 00:19:59,715
At the heart of most galaxies,
290
00:19:59,750 --> 00:20:02,062
we think now there are
supermassive black holes,
291
00:20:02,097 --> 00:20:04,410
black holes that weigh millions
or billions of times
292
00:20:04,444 --> 00:20:06,135
what our sun does.
293
00:20:06,170 --> 00:20:10,485
It's incredible that our
modern X-ray telescopes, like Chandra,
294
00:20:10,519 --> 00:20:12,625
allow us to map out
295
00:20:12,659 --> 00:20:16,801
where these fascinating black
holes are across the universe.
296
00:20:18,527 --> 00:20:22,497
Supermassive black
holes seem to be an integral feature
297
00:20:22,531 --> 00:20:24,878
of the cosmos.
298
00:20:24,913 --> 00:20:29,849
But these supermassive objects
raise questions.
299
00:20:29,883 --> 00:20:32,196
How do they form?
300
00:20:32,231 --> 00:20:36,027
And why are they so big?
301
00:20:36,062 --> 00:20:39,548
These things form
over millions to billions of years.
302
00:20:39,583 --> 00:20:41,654
So we can't watch this
happening.
303
00:20:41,688 --> 00:20:44,277
We can only see it at various
different stages
304
00:20:44,312 --> 00:20:45,934
throughout the universe.
305
00:20:45,968 --> 00:20:50,352
And so we have to just piece it
together like a jigsaw puzzle.
306
00:20:50,387 --> 00:20:54,287
Some scientists
theorize that the biggest and oldest
307
00:20:54,322 --> 00:20:59,223
black holes did not start life
as stars at all.
308
00:20:59,258 --> 00:21:01,777
In
the very early universe, we believe that
309
00:21:01,812 --> 00:21:04,746
you could have formed
very massive black hole seeds
310
00:21:04,780 --> 00:21:07,680
by direct collapse of gas.
311
00:21:07,714 --> 00:21:11,649
So these black holes are called
direct-collapse black holes.
312
00:21:11,684 --> 00:21:15,584
But the jury is still out.
313
00:21:15,619 --> 00:21:18,277
It's possible that
Sagittarius A-star formed
314
00:21:18,311 --> 00:21:20,865
by direct collapse of material.
315
00:21:20,900 --> 00:21:24,628
What I think is more likely
is that it formed by
316
00:21:24,662 --> 00:21:26,354
the death of a star.
317
00:21:26,388 --> 00:21:32,325
However Sagittarius
A-star was born, one thing is certain:
318
00:21:32,360 --> 00:21:33,982
it had to grow.
319
00:21:40,540 --> 00:21:45,752
The newly formed Sagittarius
A-star begins to feast,
320
00:21:45,787 --> 00:21:50,964
gorging itself on not just
asteroids,
321
00:21:50,999 --> 00:21:57,799
but bigger game, like stars
and massive clouds of gas.
322
00:21:57,833 --> 00:21:59,214
As it snacks on these
323
00:21:59,248 --> 00:22:03,114
nearby objects that wander
into its path, it gets bigger
324
00:22:03,149 --> 00:22:05,634
and bigger and bigger.
325
00:22:07,809 --> 00:22:11,468
The black hole gains more mass
326
00:22:11,502 --> 00:22:15,955
and more gravitational power.
327
00:22:15,989 --> 00:22:18,716
But black holes that
are a few times the mass of the sun
328
00:22:18,751 --> 00:22:21,270
can never grow to be
a supermassive black hole
329
00:22:21,305 --> 00:22:24,170
just by eating gas and stars.
330
00:22:27,173 --> 00:22:33,041
How did Sagittarius
A-star speed up its growth?
331
00:22:33,075 --> 00:22:37,425
On September 14, 2015,
an international team
332
00:22:37,459 --> 00:22:41,532
of astronomers finds a clue,
333
00:22:41,567 --> 00:22:46,399
the aftershock of a truly
titanic interaction:
334
00:22:46,434 --> 00:22:50,541
two colliding black holes.
335
00:22:50,576 --> 00:22:53,337
So the merger of two
black holes, as you might imagine,
336
00:22:53,372 --> 00:22:56,961
is spectacularly energetic.
337
00:22:56,996 --> 00:23:00,068
It is so energetic that it
causes ripples in the fabric
338
00:23:00,102 --> 00:23:01,483
of space-time itself
that propagate outward
339
00:23:01,518 --> 00:23:02,760
at the speed of light.
340
00:23:02,795 --> 00:23:06,557
And we have detected these
ripples here on Earth
341
00:23:06,592 --> 00:23:10,319
with something we call LIGO.
342
00:23:10,354 --> 00:23:14,496
LIGO is an instrument
that works by sending laser beams
343
00:23:14,531 --> 00:23:17,672
that bounce off of mirrors.
344
00:23:17,706 --> 00:23:22,780
When a gravitational wave
passes by the Earth,
345
00:23:22,815 --> 00:23:26,370
this changes the timing
of the interaction
346
00:23:26,405 --> 00:23:28,545
of those laser beams.
347
00:23:28,579 --> 00:23:31,479
The stretching
caused by a merger here on Earth
348
00:23:31,513 --> 00:23:33,170
is absolutely minuscule.
349
00:23:33,204 --> 00:23:35,034
But with advanced technology,
350
00:23:35,068 --> 00:23:36,725
LIGO was able to do it.
351
00:23:46,494 --> 00:23:51,671
Many scientists now
think that mergers like this are the key
352
00:23:51,706 --> 00:23:54,294
to how supermassive black holes,
353
00:23:54,329 --> 00:23:59,576
like our own, grow so big.
354
00:24:10,483 --> 00:24:15,384
When another black hole wanders
towards Sagittarius A-star,
355
00:24:15,419 --> 00:24:21,736
they become locked in a
gravitational embrace.
356
00:24:21,770 --> 00:24:24,911
First, it is
sort of an intriguing dance.
357
00:24:24,946 --> 00:24:27,155
They kind of dance around
each other,
358
00:24:27,189 --> 00:24:32,194
lose energy, and slowly spiral
into each other.
359
00:24:35,991 --> 00:24:38,338
This dance gets faster and
faster and faster and faster
360
00:24:38,373 --> 00:24:40,651
until they finally merge.
361
00:24:46,105 --> 00:24:50,109
Sagittarius
A-star cannibalizes its cousin...
362
00:24:54,631 --> 00:24:59,946
creating ripples in the
fabric of the universe itself.
363
00:24:59,981 --> 00:25:03,363
These mergers were
fundamental to making Sagittarius A-star
364
00:25:03,398 --> 00:25:05,504
the monster that we see today.
365
00:25:05,538 --> 00:25:08,230
They happened billions of years
ago, right at the beginning
366
00:25:08,265 --> 00:25:09,784
of Sagittarius A-star's life.
367
00:25:13,546 --> 00:25:15,306
More meals follow.
368
00:25:17,861 --> 00:25:21,381
Stars, gas clouds...
369
00:25:21,416 --> 00:25:24,315
whatever strays too close.
370
00:25:27,284 --> 00:25:31,426
And as our black hole's mass
and influence grows,
371
00:25:31,460 --> 00:25:35,188
its surroundings
are changing, too.
372
00:25:42,161 --> 00:25:45,716
The sea of stars and gas
around the black hole
373
00:25:45,751 --> 00:25:48,650
continues to grow...
374
00:25:50,618 --> 00:25:55,208
gradually evolving
into the familiar spiral disk
375
00:25:55,243 --> 00:25:58,764
we call home:
376
00:25:58,798 --> 00:26:02,664
the majestic Milky Way
with the supermassive
377
00:26:02,699 --> 00:26:06,392
Sagittarius A-star at its core.
378
00:26:15,919 --> 00:26:17,403
So when Sagittarius A-star
379
00:26:17,437 --> 00:26:19,508
becomes a supermassive
black hole,
380
00:26:19,543 --> 00:26:22,270
it really comes of age,
and it acquires the ability
381
00:26:22,304 --> 00:26:24,617
to have a transformational
impact
382
00:26:24,652 --> 00:26:27,655
on the evolution
of the entire galaxy.
383
00:26:27,689 --> 00:26:30,692
Black holes are
the ultimate engines in the universe.
384
00:26:30,727 --> 00:26:32,798
When you think about a car,
385
00:26:32,832 --> 00:26:34,627
the first thing
you're interested in is,
386
00:26:34,662 --> 00:26:36,042
how does it work?
387
00:26:36,077 --> 00:26:39,770
You open the hood and you look
at the engine of the car.
388
00:26:39,805 --> 00:26:42,290
With a black hole,
you're asking,
389
00:26:42,324 --> 00:26:45,362
"I want to lift the hood up
on an entire galaxy.
390
00:26:45,396 --> 00:26:48,986
How does a galaxy power itself
at its very heart?"
391
00:26:56,822 --> 00:26:59,065
The center of the young galaxy
392
00:26:59,100 --> 00:27:02,931
is rich with swirling gas
and dust:
393
00:27:02,966 --> 00:27:07,004
more offerings to feast on.
394
00:27:16,704 --> 00:27:20,086
This is a gluttonous period,
395
00:27:20,121 --> 00:27:24,608
a new era for
Sagittarius A-star...
396
00:27:26,714 --> 00:27:32,685
when the invisible giant has
the power to sculpt the galaxy.
397
00:27:38,173 --> 00:27:41,176
As Sagittarius
A-star is gorging on food,
398
00:27:41,211 --> 00:27:43,351
the food that
it's waiting to eat
399
00:27:43,385 --> 00:27:46,457
is swirling around the
central supermassive black hole
400
00:27:46,492 --> 00:27:49,840
in this violent, energetic disk,
401
00:27:49,875 --> 00:27:55,570
and the matter is ripped apart
by the gravity,
402
00:27:55,604 --> 00:27:57,848
which causes the protons
and electrons to then make
403
00:27:57,883 --> 00:28:00,575
these twisted
magnetic field lines.
404
00:28:00,609 --> 00:28:02,197
Everything
is rotating and orbiting,
405
00:28:02,232 --> 00:28:04,821
so at the center
of this black hole,
406
00:28:04,855 --> 00:28:06,029
this accretion disk,
407
00:28:06,063 --> 00:28:08,997
you have
a twisted magnetic field,
408
00:28:09,032 --> 00:28:10,930
almost like a tornado.
409
00:28:10,965 --> 00:28:12,483
Right before material
410
00:28:12,518 --> 00:28:15,245
approaches that event horizon...
that,
411
00:28:15,279 --> 00:28:17,696
that eternal prison,
if you will...
412
00:28:17,730 --> 00:28:21,665
it can be redirected instead.
413
00:28:21,700 --> 00:28:23,702
And from the blazing tumult,
414
00:28:23,736 --> 00:28:25,980
the super-heated material
415
00:28:26,014 --> 00:28:28,810
is thrown out
along the magnetic poles...
416
00:28:30,674 --> 00:28:36,991
two high-powered jets
launched out into the cosmos.
417
00:28:37,025 --> 00:28:39,200
They can reach hundreds of
thousands of light-years
418
00:28:39,234 --> 00:28:40,270
from the black hole itself.
419
00:28:43,963 --> 00:28:47,277
It's only recently
that we've begun to grasp
420
00:28:47,311 --> 00:28:51,937
the huge influence of
Sagittarius A-star on our galaxy
421
00:28:51,971 --> 00:28:55,216
and the role that those
super-powered jets
422
00:28:55,250 --> 00:28:56,769
may have played.
423
00:28:56,804 --> 00:28:58,357
Engines start.
424
00:28:58,391 --> 00:29:01,498
One, zero, lift-off.
425
00:29:04,950 --> 00:29:09,299
The Delta rocket carrying
a gamma ray telescope
426
00:29:09,333 --> 00:29:13,648
searching for unseen physics
in the stars of the galaxies.
427
00:29:22,484 --> 00:29:25,556
Just over a decade ago,
428
00:29:25,591 --> 00:29:31,286
astronomers made a completely
unexpected discovery.
429
00:29:31,321 --> 00:29:32,805
It was
this whole piece of our galaxy
430
00:29:32,840 --> 00:29:35,566
that we never knew
was there before.
431
00:29:35,601 --> 00:29:37,810
It would be like finding
a brand-new continent on Earth.
432
00:29:42,677 --> 00:29:47,233
The Fermi space
telescope was built to detect gamma rays,
433
00:29:47,268 --> 00:29:51,582
the most energetic radiation
in the universe.
434
00:29:51,617 --> 00:29:53,964
Fermi is
roughly 100 times as sensitive
435
00:29:53,999 --> 00:29:56,139
as previous
gamma ray telescopes.
436
00:29:56,173 --> 00:29:57,796
So it has the sensitivity
437
00:29:57,830 --> 00:30:02,662
to see things that we
just simply couldn't see before.
438
00:30:02,697 --> 00:30:06,839
Orbiting the
Earth once every 96 minutes,
439
00:30:06,874 --> 00:30:10,705
Fermi constructs
a map of the cosmos
440
00:30:10,739 --> 00:30:14,571
and uncovers
an invisible landscape...
441
00:30:14,605 --> 00:30:17,643
the most energetic regions
of the galaxy
442
00:30:17,677 --> 00:30:21,750
highlighted across the sky.
443
00:30:21,785 --> 00:30:23,614
So we pointed
the Fermi telescope
444
00:30:23,649 --> 00:30:26,686
towards our very own
supermassive black hole,
445
00:30:26,721 --> 00:30:30,414
and we had a picture of what
that area sort of looked like...
446
00:30:30,449 --> 00:30:31,450
in our minds, at least.
447
00:30:31,484 --> 00:30:34,522
But then Fermi
revealed something
448
00:30:34,556 --> 00:30:37,456
completely astonishing
and unexpected.
449
00:30:39,492 --> 00:30:42,944
Emerging from
the plane of the Milky Way
450
00:30:42,979 --> 00:30:46,430
are two enormous bubbles,
451
00:30:46,465 --> 00:30:52,436
each one stretching
25,000 light-years,
452
00:30:52,471 --> 00:30:56,613
together reaching
half the width of the galaxy.
453
00:30:59,305 --> 00:31:00,962
If you could see in gamma rays,
454
00:31:00,997 --> 00:31:02,446
the Fermi bubbles would be about
455
00:31:02,481 --> 00:31:04,483
the biggest thing
you see on the sky.
456
00:31:04,517 --> 00:31:06,485
They look like huge dumbbells
457
00:31:06,519 --> 00:31:07,658
going straight up
and straight back
458
00:31:07,693 --> 00:31:12,353
from the center of
the black hole.
459
00:31:12,387 --> 00:31:16,115
The bubbles
match the imprint scientists expect
460
00:31:16,150 --> 00:31:19,601
an enormous eruption
from Sagittarius A-star
461
00:31:19,636 --> 00:31:23,674
to leave on the galaxy.
462
00:31:23,709 --> 00:31:26,919
We had had some clues
that the Milky Way might have had
463
00:31:26,954 --> 00:31:29,680
a more energetic
and active past,
464
00:31:29,715 --> 00:31:32,028
but the incredible thing about
the Fermi bubbles
465
00:31:32,062 --> 00:31:35,790
was that they suddenly gave us
concrete evidence
466
00:31:35,824 --> 00:31:38,655
that the Milky Way
was much more energetic
467
00:31:38,689 --> 00:31:41,658
at some time in its history.
468
00:31:57,432 --> 00:32:00,642
When our black hole gorges,
469
00:32:00,677 --> 00:32:05,958
it unleashes a towering inferno
of super-heated matter.
470
00:32:09,893 --> 00:32:11,343
A supermassive black hole
471
00:32:11,377 --> 00:32:13,932
can impart something
like a trillion,
472
00:32:13,966 --> 00:32:16,210
trillion atomic bombs'
per second
473
00:32:16,244 --> 00:32:18,246
worth of energy.
474
00:32:18,281 --> 00:32:20,662
If we were
to be in the line of fire
475
00:32:20,697 --> 00:32:22,802
of one of those jets,
476
00:32:22,837 --> 00:32:23,942
it would be catastrophic for us.
477
00:32:23,976 --> 00:32:26,599
We'd be vaporized.
478
00:32:40,820 --> 00:32:43,271
Every planet in the jet's path
479
00:32:43,306 --> 00:32:46,412
could have its atmosphere
stripped away.
480
00:33:06,881 --> 00:33:08,572
But further out in the galaxy...
481
00:33:12,818 --> 00:33:16,995
these violent outbursts from
Sagittarius A-star
482
00:33:17,029 --> 00:33:20,481
may have played
a surprising role.
483
00:33:33,942 --> 00:33:39,017
Because the hot gas displaced by
the supermassive black hole
484
00:33:39,051 --> 00:33:44,056
has a calming effect
on the galaxy that hosts it.
485
00:33:44,091 --> 00:33:45,575
In order for stars to form,
486
00:33:45,609 --> 00:33:49,165
you need
very cold and very dense gas,
487
00:33:49,199 --> 00:33:52,340
because stars form through
the collapse of material.
488
00:33:52,375 --> 00:33:55,309
So, instead, if you have
489
00:33:55,343 --> 00:33:57,690
something like
a supermassive black hole
490
00:33:57,725 --> 00:34:00,555
that is sending out
these hot jets
491
00:34:00,590 --> 00:34:02,764
into the galaxy around it,
492
00:34:02,799 --> 00:34:05,698
those jets are going to
heat up the gas.
493
00:34:05,733 --> 00:34:08,253
Now the gas is
no longer cold enough
494
00:34:08,287 --> 00:34:10,255
to collapse
and then form a star.
495
00:34:12,395 --> 00:34:14,742
There's a symbiotic relationship
496
00:34:14,776 --> 00:34:16,882
between the supermassive
black hole at the center
497
00:34:16,916 --> 00:34:19,643
and its host galaxy.
498
00:34:19,678 --> 00:34:22,198
And this relationship determines
499
00:34:22,232 --> 00:34:24,959
the rate at which stars form,
planets form,
500
00:34:24,993 --> 00:34:27,755
and ultimately, in some sense,
501
00:34:27,789 --> 00:34:29,067
why we are here.
502
00:34:49,777 --> 00:34:52,124
After spending billions of years
503
00:34:52,159 --> 00:34:57,750
consuming the gas, dust,
and stars around it,
504
00:34:57,785 --> 00:35:00,891
there is little left
to feast on.
505
00:35:05,379 --> 00:35:08,761
Our black hole falls dormant.
506
00:35:11,316 --> 00:35:17,287
Today, the Milky Way
has entered an era of calm
507
00:35:17,322 --> 00:35:21,809
and Sagittarius A-star
is a sleeping giant,
508
00:35:21,843 --> 00:35:26,124
the enormous bubbles spotted by
the Fermi telescope
509
00:35:26,158 --> 00:35:29,057
echoes of a lively past.
510
00:35:29,092 --> 00:35:30,576
You never want to assume that
511
00:35:30,611 --> 00:35:33,234
you live at a special time
in the history of the universe.
512
00:35:33,269 --> 00:35:36,272
But it is kind of a special time
513
00:35:36,306 --> 00:35:38,343
that, right now,
the black hole is very quiet,
514
00:35:38,377 --> 00:35:40,034
and it must have been
much more active
515
00:35:40,068 --> 00:35:43,693
a few million years ago.
516
00:35:47,904 --> 00:35:49,940
As our understanding has grown,
517
00:35:49,975 --> 00:35:54,152
our picture of black holes
has transformed,
518
00:35:54,186 --> 00:35:57,672
no longer sinister monsters,
519
00:35:57,707 --> 00:36:00,365
but agents of
change and creation.
520
00:36:00,399 --> 00:36:04,231
Sculptors of the cosmos.
521
00:36:04,265 --> 00:36:05,508
We are far from
522
00:36:05,542 --> 00:36:08,062
unlocking all the secrets
523
00:36:08,096 --> 00:36:10,340
of our galaxy's
supermassive black hole.
524
00:36:10,375 --> 00:36:12,963
And in fact,
the stuff that remains
525
00:36:12,998 --> 00:36:15,103
is probably
the most interesting:
526
00:36:15,138 --> 00:36:19,177
what happens inside
a supermassive black hole
527
00:36:19,211 --> 00:36:22,007
and at its event horizon.
528
00:36:27,115 --> 00:36:30,981
Black holes
challenge the most basic principle
529
00:36:31,016 --> 00:36:34,537
about the predictability of
the universe
530
00:36:34,571 --> 00:36:37,436
and the certainty of history.
531
00:36:40,163 --> 00:36:43,822
Nothing could get out of
a black hole.
532
00:36:43,856 --> 00:36:45,824
Or so it was thought.
533
00:36:50,829 --> 00:36:52,071
Black holes are where
534
00:36:52,106 --> 00:36:58,181
two of our greatest theories
collide and clash.
535
00:36:58,216 --> 00:37:01,115
So you've got these
two primal forces in the universe:
536
00:37:01,149 --> 00:37:05,464
gravity, which we all understand
and feel with our bones.
537
00:37:05,499 --> 00:37:07,294
And then you've got
quantum mechanics,
538
00:37:07,328 --> 00:37:10,504
which governs
the theory of the ultra-small,
539
00:37:10,538 --> 00:37:12,299
how atoms
and nuclei come together.
540
00:37:12,333 --> 00:37:14,508
The black hole
541
00:37:14,542 --> 00:37:18,132
is where gravity and
quantum mechanics finally meet.
542
00:37:18,166 --> 00:37:21,722
SYLVESTER JAMES GATES, JR.: When we try
to take the mathematics of the very large
543
00:37:21,756 --> 00:37:23,517
and try to combine that with
544
00:37:23,551 --> 00:37:25,346
the mathematics of
the very small,
545
00:37:25,381 --> 00:37:28,142
instead of matching...
546
00:37:28,176 --> 00:37:29,488
They get into a fight.
547
00:37:29,523 --> 00:37:33,216
And so we don't have a
consistent way to describe both.
548
00:37:35,391 --> 00:37:38,152
We can begin
to probe this deep mystery
549
00:37:38,186 --> 00:37:42,605
by investigating the heart of
Sagittarius A-star.
550
00:37:46,540 --> 00:37:52,270
Scientists have studied
dozens of stars in its orbit,
551
00:37:52,304 --> 00:37:56,032
some passing just
a few billion miles
552
00:37:56,066 --> 00:37:58,862
from the event horizon,
553
00:37:58,897 --> 00:38:03,073
a hair's width
on galactic scales.
554
00:38:03,108 --> 00:38:07,526
And these fly-bys could have
catastrophic consequences...
555
00:38:16,673 --> 00:38:21,609
because some of these stars
likely have planets in orbit.
556
00:38:24,819 --> 00:38:29,617
Planets that
may stray too close.
557
00:38:29,652 --> 00:38:32,586
Moths to a flame.
558
00:38:37,107 --> 00:38:39,834
Pulled from their parent stars
559
00:38:39,869 --> 00:38:42,734
towards the abyss.
560
00:38:42,768 --> 00:38:45,046
So imagine
you're some alien civilization
561
00:38:45,081 --> 00:38:47,877
looking up at your lovely
home star, S2, in the sky.
562
00:38:47,911 --> 00:38:52,088
And one day, the thing starts
wandering closer and closer
563
00:38:52,122 --> 00:38:54,504
to what we call
the tidal disruption radius
564
00:38:54,539 --> 00:38:55,781
of Sagittarius A-star,
565
00:38:55,816 --> 00:39:00,476
this four-million-solar-mass
black hole.
566
00:39:00,510 --> 00:39:02,340
If you fell into a black hole,
567
00:39:02,374 --> 00:39:05,481
you'd pass the event horizon,
and actually,
568
00:39:05,515 --> 00:39:07,862
bizarrely, you'd see nothing.
569
00:39:07,897 --> 00:39:13,143
There's no physical barrier,
there's no big line in space
570
00:39:13,178 --> 00:39:16,664
saying
"point of no return."
571
00:39:16,699 --> 00:39:19,943
You would just drift
very casually, gently
572
00:39:19,978 --> 00:39:22,912
across the event horizon.
573
00:39:24,500 --> 00:39:25,984
If we could stand on
574
00:39:26,018 --> 00:39:30,160
such a planet and look outwards,
575
00:39:30,195 --> 00:39:33,612
we'd see something spectacular.
576
00:39:39,825 --> 00:39:42,621
You would
see a distorted universe,
577
00:39:42,656 --> 00:39:45,900
and in fact,
you'd see it distorted
578
00:39:45,935 --> 00:39:49,904
in both time and space.
579
00:39:49,939 --> 00:39:52,044
You'd see it playing out
580
00:39:52,079 --> 00:39:55,807
at an amazingly fast speed.
581
00:39:55,841 --> 00:39:58,706
The rest of time would
play out unbelievably fast
582
00:39:58,741 --> 00:40:00,708
in front of your eyes.
583
00:40:03,573 --> 00:40:07,577
But eventually,
tidal and gravitational forces
584
00:40:07,612 --> 00:40:10,615
become too strong...
585
00:40:13,963 --> 00:40:19,037
stretching space
and everything in it.
586
00:40:19,071 --> 00:40:21,073
Your feet would be pulled
587
00:40:21,108 --> 00:40:22,765
more strongly by gravity
than your head,
588
00:40:22,799 --> 00:40:26,872
so you'd be stretched out
into a giant string,
589
00:40:26,907 --> 00:40:31,325
and eventually, you'd be
one long string one atom thick.
590
00:40:31,359 --> 00:40:36,019
We call this spaghettification.
591
00:40:36,054 --> 00:40:39,333
Boulders become rocks.
592
00:40:39,367 --> 00:40:41,197
Rocks become sand,
593
00:40:41,231 --> 00:40:43,786
whose very atoms
594
00:40:43,820 --> 00:40:48,998
are then pulled apart.
595
00:40:49,032 --> 00:40:53,761
Gravity and
the quantum world collide.
596
00:40:53,796 --> 00:40:57,489
Ahead, the heart of
the black hole...
597
00:40:57,524 --> 00:41:00,803
the singularity,
598
00:41:00,837 --> 00:41:05,152
where all journeys in terminate.
599
00:41:05,186 --> 00:41:06,533
Our idea of a singularity
600
00:41:06,567 --> 00:41:08,293
is that everything is compressed
601
00:41:08,327 --> 00:41:11,261
beyond what it can be
until it's nothing,
602
00:41:11,296 --> 00:41:13,263
but yet still exists.
603
00:41:13,298 --> 00:41:15,507
That is...
604
00:41:15,542 --> 00:41:18,027
Wow.
605
00:41:41,153 --> 00:41:42,948
Over trillions of years,
606
00:41:42,983 --> 00:41:46,089
all the stars around
Sagittarius A-star
607
00:41:46,124 --> 00:41:49,714
will gradually fade
out of existence.
608
00:42:01,588 --> 00:42:05,039
Long after the
last-ever sun sets on any planet,
609
00:42:05,074 --> 00:42:06,972
black holes will continue
to roam the universe.
610
00:42:14,290 --> 00:42:16,810
The final dark age.
611
00:42:23,230 --> 00:42:24,334
If nothing can ever escape,
612
00:42:24,369 --> 00:42:26,647
if this is some eternal prison,
613
00:42:26,682 --> 00:42:28,269
is that the end of the story?
614
00:42:31,963 --> 00:42:33,827
Perhaps not.
615
00:42:33,861 --> 00:42:37,071
Because scientists
now believe that even
616
00:42:37,106 --> 00:42:39,557
Sagittarius A-star will die.
617
00:42:45,183 --> 00:42:48,945
And its death
will come at the hands of
618
00:42:48,980 --> 00:42:52,328
what might seem an
inconsequential effect
619
00:42:52,362 --> 00:42:55,883
first described
almost five decades ago.
620
00:42:57,436 --> 00:42:58,783
So in 1975,
621
00:42:58,817 --> 00:43:02,165
Stephen Hawking
published this amazing paper
622
00:43:02,200 --> 00:43:07,619
showing that black holes aren't
absolutely, completely black.
623
00:43:07,654 --> 00:43:10,933
They glow very, very faintly.
624
00:43:10,967 --> 00:43:15,627
They have a temperature
associated with them.
625
00:43:15,662 --> 00:43:18,561
And you can write
that temperature
626
00:43:18,596 --> 00:43:24,256
very simply in an equation
627
00:43:24,291 --> 00:43:25,637
that's just beautiful.
628
00:43:25,672 --> 00:43:28,744
It links together so many
different parts of physics.
629
00:43:28,778 --> 00:43:30,262
It's got gravity in it.
630
00:43:30,297 --> 00:43:32,644
It's got the mass
of the black hole in it.
631
00:43:32,679 --> 00:43:34,646
It's got the speed of light.
632
00:43:34,681 --> 00:43:37,511
It's got constants relating to
atomic physics,
633
00:43:37,545 --> 00:43:39,030
the microworld.
634
00:43:39,064 --> 00:43:42,550
And it's putting
all of these together
635
00:43:42,585 --> 00:43:44,518
and giving us a temperature.
636
00:43:44,552 --> 00:43:47,832
Hawking's
equation has huge implications
637
00:43:47,866 --> 00:43:50,455
for the future
of the black hole.
638
00:43:50,489 --> 00:43:52,733
So if something
has a temperature,
639
00:43:52,768 --> 00:43:54,839
it's glowing, it's radiating.
640
00:43:54,873 --> 00:43:56,737
Like when you put your hand
close to a fire,
641
00:43:56,772 --> 00:43:57,738
you can feel it.
642
00:43:57,773 --> 00:44:00,638
And that losing energy,
643
00:44:00,672 --> 00:44:03,606
for a black hole like
Sagittarius A-star,
644
00:44:03,641 --> 00:44:06,436
over timescales
that are hugely long,
645
00:44:06,471 --> 00:44:10,751
it's going to evaporate away.
646
00:44:10,786 --> 00:44:13,651
It's going to disappear.
647
00:44:26,836 --> 00:44:28,907
Very gradually,
648
00:44:28,942 --> 00:44:31,047
this Hawking radiation
649
00:44:31,082 --> 00:44:36,639
will erode away
Sagittarius A-star
650
00:44:36,674 --> 00:44:40,919
until, many trillions
and trillions of years
651
00:44:40,954 --> 00:44:43,059
into the future...
652
00:44:49,894 --> 00:44:52,828
in a final burst of light...
653
00:44:57,729 --> 00:45:03,217
our black hole will disappear.
654
00:45:03,252 --> 00:45:06,773
And then the Milky Way
will be completely dark
655
00:45:06,807 --> 00:45:09,776
for all eternity.
656
00:45:12,606 --> 00:45:13,952
So why does it matter
657
00:45:13,987 --> 00:45:15,782
if these black holes
disintegrate
658
00:45:15,816 --> 00:45:18,854
in the far distant future?
659
00:45:18,888 --> 00:45:22,547
Well, the discovery of
Hawking radiation
660
00:45:22,581 --> 00:45:25,653
raised some
profound questions in physics.
661
00:45:25,688 --> 00:45:28,691
If I was to set fire
to this piece of paper
662
00:45:28,726 --> 00:45:31,832
with Stephen Hawking's equation
written on it...
663
00:45:33,972 --> 00:45:37,044
what happens to all that
information as it burns away,
664
00:45:37,079 --> 00:45:39,322
as it radiates away?
665
00:45:39,357 --> 00:45:45,466
Do we lose it
from the universe forever?
666
00:45:56,823 --> 00:46:01,897
Maybe if I could sweep up
all the ash,
667
00:46:01,931 --> 00:46:05,866
if I could find all the photons
668
00:46:05,901 --> 00:46:08,973
and reconstruct them,
669
00:46:09,007 --> 00:46:12,942
maybe I could reconstruct
that piece of paper,
670
00:46:12,977 --> 00:46:17,119
even the equation written on it.
671
00:46:17,153 --> 00:46:20,087
So does this also apply to
black holes?
672
00:46:20,122 --> 00:46:23,366
What happened to
all the information
673
00:46:23,401 --> 00:46:25,472
contained on all the material
674
00:46:25,506 --> 00:46:27,405
that ever fell into
a black hole?
675
00:46:27,439 --> 00:46:32,755
And as a black hole evaporates,
what happens to it?
676
00:46:38,830 --> 00:46:43,352
Black holes ain't
as black as they are painted.
677
00:46:43,386 --> 00:46:47,770
They are not the eternal prisons
they were once thought.
678
00:46:51,291 --> 00:46:56,779
So if you feel you are in
a black hole, don't give up.
679
00:47:00,162 --> 00:47:02,820
There's a way out.
680
00:47:09,205 --> 00:47:13,347
If information somehow
escapes from Sagittarius A-star
681
00:47:13,382 --> 00:47:15,384
as it evaporates away,
682
00:47:15,418 --> 00:47:19,595
the implication is profound.
683
00:47:19,629 --> 00:47:23,081
Scientists now believe
that every star,
684
00:47:23,116 --> 00:47:25,083
asteroid,
685
00:47:25,118 --> 00:47:26,533
planet...
686
00:47:26,567 --> 00:47:30,986
everything that ever fell into
Sagittarius A-star...
687
00:47:31,020 --> 00:47:34,023
may live on,
688
00:47:34,058 --> 00:47:36,336
every aspect and position
689
00:47:36,370 --> 00:47:41,582
of every particle
encoded as information.
690
00:47:43,308 --> 00:47:45,552
All that you would
theoretically need
691
00:47:45,586 --> 00:47:48,589
to put the whole back together.
692
00:47:50,764 --> 00:47:53,180
So the memory of
every single thing
693
00:47:53,215 --> 00:47:55,217
that's "fallen into,"
become part of,
694
00:47:55,251 --> 00:47:56,804
Sagittarius A-star
in the Milky Way
695
00:47:56,839 --> 00:47:57,875
hasn't been lost.
696
00:47:57,909 --> 00:47:59,462
It's still there.
697
00:47:59,497 --> 00:48:02,293
It's just that
we can't access that now.
698
00:48:02,327 --> 00:48:06,918
But maybe we might be able
to read the ashes of that memory
699
00:48:06,953 --> 00:48:10,094
in the far future of
the universe.
700
00:48:10,128 --> 00:48:15,133
But how can
anything escape a black hole's grip?
701
00:48:15,168 --> 00:48:17,066
The defining
fact of a black hole
702
00:48:17,101 --> 00:48:19,482
is that nothing
should be able to get out.
703
00:48:19,517 --> 00:48:22,278
And yet when you look at
Hawking radiation,
704
00:48:22,313 --> 00:48:25,074
it seems to be suggesting
that quantum physics
705
00:48:25,109 --> 00:48:29,285
does connect up the inside
back to the outside.
706
00:48:29,320 --> 00:48:34,256
We just don't really know how.
707
00:48:34,290 --> 00:48:36,637
Black holes force us to
708
00:48:36,672 --> 00:48:42,264
consider nature in entirely new
and mind-bending ways.
709
00:48:42,298 --> 00:48:45,060
People aren't
at all certain about the resolution
710
00:48:45,094 --> 00:48:48,511
to what happens when we
throw things into black holes,
711
00:48:48,546 --> 00:48:49,685
as far as where
the information goes.
712
00:48:49,719 --> 00:48:51,031
It's still an open question.
713
00:48:51,066 --> 00:48:53,827
Maybe it gets sent to
a portal to another dimension,
714
00:48:53,861 --> 00:48:56,692
maybe it gets pumped
into some other branch
715
00:48:56,726 --> 00:48:59,315
of a larger multiverse.
716
00:48:59,350 --> 00:49:01,386
Some people imagine that
black holes are really
717
00:49:01,421 --> 00:49:05,045
just a kind of quantum fuzz,
a fuzzball.
718
00:49:05,080 --> 00:49:06,978
Some people
think that all the information
719
00:49:07,013 --> 00:49:08,255
that fell into the black hole
720
00:49:08,290 --> 00:49:09,981
is somehow encoded on
its surface
721
00:49:10,016 --> 00:49:12,225
in a hologram.
722
00:49:12,259 --> 00:49:15,021
But we're not
really privy to any of this information.
723
00:49:15,055 --> 00:49:17,092
And if we want to find out,
we'd have to go in.
724
00:49:19,473 --> 00:49:21,993
Whatever
the solution proves to be,
725
00:49:22,028 --> 00:49:23,891
it will have ramifications
726
00:49:23,926 --> 00:49:27,585
far beyond
the black hole itself.
727
00:49:30,726 --> 00:49:35,110
This theory of quantum
gravity that's so elusive right now,
728
00:49:35,144 --> 00:49:36,870
that is what we would need
to describe
729
00:49:36,904 --> 00:49:40,011
what's happening
inside black holes,
730
00:49:40,046 --> 00:49:42,324
could either be
the most exciting development
731
00:49:42,358 --> 00:49:47,156
to happen in the next decade or
maybe even the next century,
732
00:49:47,191 --> 00:49:50,642
or it could be an alarm bell
going off in our heads
733
00:49:50,677 --> 00:49:53,024
that maybe
Einstein's theory of gravity
734
00:49:53,059 --> 00:49:57,339
is not
the final word on gravity.
735
00:49:57,373 --> 00:49:59,927
Solving
the mystery of black holes
736
00:49:59,962 --> 00:50:04,587
may be our best chance to
complete the picture of nature
737
00:50:04,622 --> 00:50:07,866
that has eluded us
for the last century.
738
00:50:07,901 --> 00:50:09,006
So perhaps the important thing
739
00:50:09,040 --> 00:50:11,387
isn't what the answer
turns out to be.
740
00:50:11,422 --> 00:50:13,493
The important thing is
that we will gain
741
00:50:13,527 --> 00:50:15,288
a fuller understanding of
the cosmos
742
00:50:15,322 --> 00:50:16,737
by studying
these remarkable objects.
743
00:50:16,772 --> 00:50:21,570
Studying the universe has
completely changed our universe.
744
00:50:21,604 --> 00:50:25,436
We have to rethink everything
over and over again.
745
00:50:25,470 --> 00:50:27,955
Like, it's almost, like,
tear up the universe we know
746
00:50:27,990 --> 00:50:31,890
and write a new one.
747
00:50:31,925 --> 00:50:33,996
We're still a long way from
748
00:50:34,031 --> 00:50:38,966
fully comprehending
the secrets of black holes,
749
00:50:39,001 --> 00:50:41,659
but we're beginning to
lift the veil.
750
00:50:45,180 --> 00:50:49,011
Far from being
mere cosmic aberrations,
751
00:50:49,046 --> 00:50:54,396
black holes fundamentally
shape our universe.
752
00:50:56,605 --> 00:50:57,813
So it's extraordinary
to think that
753
00:50:57,847 --> 00:50:59,332
we might be
fundamentally connected
754
00:50:59,366 --> 00:51:01,265
to something that
we didn't know existed
755
00:51:01,299 --> 00:51:03,681
for the vast span of
human history.
756
00:51:07,236 --> 00:51:08,962
The beautiful
thing about black holes
757
00:51:08,996 --> 00:51:11,344
is that they're such a
rich source of information.
758
00:51:11,378 --> 00:51:14,174
We've learned so much
about the universe
759
00:51:14,209 --> 00:51:15,900
from studying black holes:
760
00:51:15,934 --> 00:51:17,557
space, time,
761
00:51:17,591 --> 00:51:19,800
the very fundamental nature of
reality.
762
00:51:21,423 --> 00:51:23,735
Bit by bit revealing
763
00:51:23,770 --> 00:51:27,636
the deepest mysteries of
the cosmos.
764
00:51:27,670 --> 00:51:31,053
We're in a golden
age of discovery about black holes.
765
00:51:31,088 --> 00:51:33,055
We understand how they merge,
766
00:51:33,090 --> 00:51:35,644
we've discovered
their colossal jets,
767
00:51:35,678 --> 00:51:37,266
and we're beginning to see them
768
00:51:37,301 --> 00:51:41,132
not just as destroyers,
but also as creators
769
00:51:41,167 --> 00:51:43,583
and sculptors.
770
00:51:43,617 --> 00:51:46,758
And all that
is just the beginning.
771
00:51:46,793 --> 00:51:48,622
Our story's happening now,
772
00:51:48,657 --> 00:51:51,798
but black holes,
they're going to outlive us
773
00:51:51,832 --> 00:51:54,041
by trillions of years.
774
00:51:54,076 --> 00:51:57,114
Their story
is just getting started.
60254
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