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ROWE: First there was light,
visible light.
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Then, we viewed the universe
in radio waves and X-rays.
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Ever since
there's been astronomy,
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we've been looking at
different kinds of light
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and opening up the universe
a little bit more of the time.
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But then in 2015, like,
the roof came off.
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THALLER: Something happened
that changed everything,
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the ability to see waves
in space and time itself.
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ROWE: Gravitational waves.
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They help us roll back
the clock to the dawn of time,
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discover epic cosmic collisions,
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on make Earth-shaking
discoveries.
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Gravitational waves
are the biggest game changer
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since the invention of
the telescope.
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We have a completely new
universe to view now.
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ROWE: A new exploration of
space is just beginning.
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[electricity buzzing]
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[explosion blasts]
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Long ago, 17 billion
light-years away,
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a cataclysmic showdown
plays out.
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Two black holes locked together
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in a deadly cosmic dance.
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Black holes are unimaginably
dense objects with gravity
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so intense that if you get
too close to them,
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you're gone.
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ROWE: Their immense
gravitational pull causes
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them to spiral towards
each other.
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OLUSEYI: When black holes
collide, they don't just run
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into each other.
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They're in orbit about
each other.
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So what we're talking about is
an inspiralling orbit
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that goes faster and faster
and faster and faster.
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ROWE: Until they finally
collide in a fatal embrace.
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[explosion blasts]
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But astronomers
don't see a thing.
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The problem with observing
colliding black holes is all
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about the name, black holes,
they give off no light.
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How can astronomers see
something that
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no telescope can detect?
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ROWE: Across the universe,
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extraordinary events take place.
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But we sometimes miss them,
because we rely on light.
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Now, astronomers have
a new toolkit that's
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revealing the cosmos in
a totally different way...
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...using the very fabric of
our universe
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we call spacetime.
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Everything with mass,
like stars,
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planets, and black holes,
all curve this fabric.
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The more massive the object,
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the bigger the distortion
of spacetime.
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The classical analogy is
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this stretched rubber
sheet, right?
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And, like, a mass, like, the sun
is, like, a ball on this sheet,
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and it distorts and warps
the sheet
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into this valley, right?
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And if you roll a marble
across it like the marble is
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a planet, the marble will be
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pulled into orbit
around the ball because
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of the curvature of the sheet.
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ROWE: But that's only half
the picture.
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If an object has mass and is
accelerating through
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spacetime, it creates ripples
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in that fabric of spacetime,
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and we call these
gravitational waves.
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ROWE: Gravitational waves
give us vital clues
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about distant objects
that we can't see.
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The more massive the object that
produces them and the faster
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it's moving,
the bigger the ripples.
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These ripples pass through
planets, stars, and galaxies
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with ease.
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When a gravitational wave
passes through an object like
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a star or a planet or a person,
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it stretches
and compresses them,
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like with this tennis ball.
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Now, if you're close to
a powerful source of
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gravitational waves,
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like merging supermassive
black holes,
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those waves are incredibly
strong, and they're capable of
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actually destroying a planet.
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ROWE: But like the ripples
on a pond,
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their strength and size
diminishes over distance.
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The farther away you are,
the weaker they get.
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And when they're hundreds of
millions of light-years away,
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they're actually smaller
than the size of an atom.
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ROWE: So, to listen
for gravitational waves,
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scientists built the most
sensitive measuring device on
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the planet.
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This is LIGO,
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the Laser Interferometer
Gravitational-Wave Observatory,
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two enormous detectors
located almost 2,000 miles
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apart in Louisiana
and Washington state.
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Each sensor has L-shaped arms,
measuring 2.5 miles.
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Inside the LIGO detectors,
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inside these concrete tunnels,
there is a laser system.
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It's called an interferometer,
so light comes in from
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a laser beam and is split
into two paths.
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ROWE: Normally, the lengths of
the two beams are the same.
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That changes when
gravitational waves
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hit the beams.
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When a gravitational wave
passes through,
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it changes the distance that
light travels along these arms,
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so one arm effectively gets
longer, and the other one
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gets shorter.
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The length of those two beams
varies just ever so slightly,
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and the very sensitive apparatus
in LIGO is able to pick that up.
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ROWE: With this ultra-sensitive
laser system,
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LIGO picks up distortions in
spacetime, narrower than
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one millionth of the diameter
of an atom.
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Just that feat,
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just the fact that we were
able to build
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a detector to detect
gravitational waves
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is just mind-boggling.
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All of a sudden now,
we were listening
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to the faintest whispers
of the universe.
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ROWE: In 2015, LIGO picked up
a whisper that had
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been traveling towards Earth
for over a billion years.
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Its source? Two colliding
stellar black holes.
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Watching two black holes
spiral in and merge --
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That's not something
we can do using optical
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telescopes or X-ray telescopes
or anything like that.
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But with LIGO, we could
actually detect that event.
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[explosion blasts]
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ROWE: Now, scientists can paint
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accurate pictures of
invisible objects.
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You can tell you're looking
at black holes.
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You can get their masses,
you can get their distance.
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There's a phenomenal amount of
information in that wave.
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ROWE:
The colliding black holes are
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the most massive LIGO has
ever detected.
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One is 66 times
the mass of our sun,
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the other, 85 times
the mass of our sun.
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PLAIT: As two black holes
are spiraling in,
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they are moving faster
and faster
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as they get closer and closer.
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That means that
the gravitational waves
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they're emitting have
a higher and higher frequency.
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So as time goes on,
the pitch gets higher.
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So it goes...
[increasing pitch] ooop!
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[increasing pitch] Ooop!
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[increasing pitch] Zhhhrp!
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[repeating noise
with increasing pitch]
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ROWE: When they finally merge,
they create a giant.
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PONTZEN: By analyzing that data,
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it's possible to establish
that the new black hole from
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the merger of these two original
black holes weighs as much as
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something like 140 times
the mass of our sun.
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It's really difficult
to overstate
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the importance of
gravitational wave detection.
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It's like adding on
an entirely new sense --
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All of a sudden,
there's a brand-new way
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to explore the rest
of the universe.
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ROWE: Invisible cosmic
collisions are just
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the beginning of what
gravitational wave
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astronomy can reveal to us.
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Now, scientists are using
gravitational waves
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to revisit other
long-standing mysteries,
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like what causes
the brightest explosions
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in the cosmos?
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This is not
an everyday car crash.
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This is the most dramatic
event that
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you're ever gonna see
in our universe.
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ROWE: Across the universe,
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strange bursts of light
puzzle astronomers.
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For just a fraction of a second,
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they shine more than
a trillion times brighter
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than the sun --
Then, they vanish.
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These brief flashes of light
are known
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as gamma-ray bursts
or GRBs for short,
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and they're such a mystery,
because they are
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insanely energetic, and we
don't know what causes them.
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[explosion blasts]
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ROWE: For decades,
these short gamma-ray bursts
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have been an enigma.
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No explanation was off limits,
no matter how wild.
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Is it a supernova?
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Is it on alien civilization
saying hello?
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You know, we just don't know.
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ROWE: In August 2017,
the Fermi Gamma-ray Telescope
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detected another
short gamma-ray burst,
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but this one was different,
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So a gamma-ray burst went off
130 million light-years away,
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and it actually produced
a ripple in space and time
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that LIGO could detect.
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ROWE:
Gravitational waves could help
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finally reveal what causes
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one of the brightest
explosions in the universe.
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LIGOS data suggests
the culprit could be two
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massive objects spiraling
towards each other
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and colliding.
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But based on the gravitational
wave data,
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these two objects were
too small to be black holes.
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They had to be something else.
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ROWE: Not black holes,
but the ultra dense
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cores of collapsed stars
called neutron stars.
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ESQUIVE: A neutron star is
what's left over
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after a massive star
collapses in on itself.
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It's very, very dense, because
it took all, essentially,
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the mass of the core and
contracted it into a really,
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really small radius.
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ROWE: As the dense neutron stars
spiral ever closer,
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the gravitational wave signal
gets stronger and stronger,
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until they collide, releasing
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an epic burst of
gravitational waves.
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PONTZEN: Because
they're not black holes,
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light can get out.
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And if you smash two things
together at these kind of
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absolutely massive speeds,
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there's a huge amount of
energy involved.
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ROWE: Energy we detected both as
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invisible gravitational waves
and visible light.
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Could this light be a mysterious
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and ultra-powerful
gamma-ray burst?
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How could these colliding
dead stars be associated
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with gamma-ray bursts,
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which are in fact, the most
energetic explosions we see in
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the entire universe?
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ROWE: Neutron stars have
powerful magnetic fields
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that trap particles of
gas and dust.
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During a collision,
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the swirling magnetic fields
twist up,
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building up more
and more energy.
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You have lots of little
particles of matter that are
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trying to keep up with these
rapidly spinning magnetic
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fields -- that starts swooshing
them round until they reach
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pretty much the speed of light,
and eventually,
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they're kind of shot out of
the remnant in a tight beam.
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ROWE:
The beam is a gamma-ray burst,
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00:13:09,188 --> 00:13:11,489
but they're not always
easy to detect.
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If the jet coming out
is pointed right at you,
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then you see this extremely
high energy event,
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the gamma-ray burst.
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ROWE: If it's not pointed at us,
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we might miss it.
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Fortunately,
the gravitational waves
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show us where to look.
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Following the gamma-ray burst,
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we spotted a strange red cloud,
evidence of a heavy
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element factory.
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SUTTER:
After the initial collision,
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there is a shell of debris
moving outwards,
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but then, high-energy neutrons
come slamming into this
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material and start to build
heavier elements,
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one after another.
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00:14:02,608 --> 00:14:07,712
We can see the gold,
we can see the potassium,
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00:14:07,813 --> 00:14:11,616
we can see the plutonium
being created
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before our very eyes.
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ROWE: The neutron star collision
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produced huge quantities
of heavy elements,
249
00:14:22,194 --> 00:14:25,597
blasting out enough gold and
platinum to weigh more than 10
250
00:14:25,698 --> 00:14:27,832
times the mass of the Earth,
251
00:14:27,933 --> 00:14:30,301
solving a long-standing mystery.
252
00:14:30,402 --> 00:14:31,803
We knew that
253
00:14:31,904 --> 00:14:34,639
supernova explosions did
create some
254
00:14:34,740 --> 00:14:35,874
of the heavier elements.
255
00:14:35,975 --> 00:14:39,344
But from everything
we've observed about supernova,
256
00:14:39,478 --> 00:14:43,815
they don't happen often enough
to really populate a galaxy
257
00:14:43,916 --> 00:14:46,751
with all of the heavier
elements that we observed.
258
00:14:46,852 --> 00:14:49,921
This was the missing piece.
259
00:14:50,022 --> 00:14:52,924
The gold on your wedding ring,
260
00:14:53,025 --> 00:14:55,159
the gold in your jewelry,
261
00:14:55,261 --> 00:14:57,395
was formed and forged from
262
00:14:57,496 --> 00:15:00,932
a titanic collision before
the Earth even existed.
263
00:15:03,869 --> 00:15:06,137
ROWE: The combination of
gravitational waves
264
00:15:06,238 --> 00:15:07,238
and telescopes
265
00:15:08,974 --> 00:15:12,010
proves that neutron star
collisions create
266
00:15:12,111 --> 00:15:14,412
precious metals
267
00:15:14,513 --> 00:15:17,382
and cause super-bright
gamma-ray bursts.
268
00:15:18,884 --> 00:15:23,421
When you can measure
a gravitational wave signal
269
00:15:23,522 --> 00:15:25,857
and a light signal
like a gamma-ray burst,
270
00:15:25,958 --> 00:15:29,027
you get a whole new way
to solve complicated,
271
00:15:29,128 --> 00:15:31,696
intertwined physical processes.
272
00:15:33,866 --> 00:15:36,534
TREMBLAY: It's like you're
watching a symphony on mute,
273
00:15:36,635 --> 00:15:38,903
and then you hit that button,
and the sound comes on,
274
00:15:39,004 --> 00:15:41,372
and it's just a completely
different picture.
275
00:15:45,144 --> 00:15:49,881
ROWE: The sounds of the cosmos
don't just reveal collisions.
276
00:15:53,953 --> 00:15:57,422
It turns out, we can use
gravitational waves to help us
277
00:15:57,523 --> 00:16:00,591
understand some of the biggest
mysteries of the cosmos.
278
00:16:13,572 --> 00:16:15,707
ROWE: Gravitational waves
are a new way
279
00:16:15,808 --> 00:16:19,577
to listen to the universe,
revealing unseen,
280
00:16:19,678 --> 00:16:24,115
epic cosmic events and adding
vital details to our picture
281
00:16:24,216 --> 00:16:25,416
of the cosmos.
282
00:16:28,187 --> 00:16:31,756
Every new way we figure
out to probe the universe is
283
00:16:31,857 --> 00:16:34,892
a good thing, and detecting
gravitational waves,
284
00:16:34,994 --> 00:16:37,395
it's a new dimension to being
able to study the universe.
285
00:16:37,496 --> 00:16:39,664
It's like -- it's like
having a new sense.
286
00:16:42,501 --> 00:16:45,269
ROWE: This new sense could be
just what astronomers need
287
00:16:45,371 --> 00:16:48,906
to answer some of the biggest
questions in physics,
288
00:16:49,008 --> 00:16:51,676
like, "What is the speed
of gravity?"
289
00:16:53,178 --> 00:16:56,114
And, "Does it travel at
the universe's speed limit?"
290
00:16:57,916 --> 00:17:00,284
OLUSEYI: One of the things we
learn early in science is that
291
00:17:00,386 --> 00:17:02,854
the universe has
an absolute speed limit,
292
00:17:02,955 --> 00:17:05,423
which is the speed of light in
a vacuum,
293
00:17:05,524 --> 00:17:08,693
which is
186,000 miles per second.
294
00:17:11,563 --> 00:17:13,464
ROWE: Light from the sun
takes eight minutes
295
00:17:13,565 --> 00:17:15,833
and 20 seconds to reach Earth.
296
00:17:15,934 --> 00:17:19,370
So, if the sun disappeared,
297
00:17:19,471 --> 00:17:21,439
we wouldn't miss its
light immediately.
298
00:17:23,142 --> 00:17:25,943
But how quickly would we
notice its missing gravity?
299
00:17:27,546 --> 00:17:30,681
OLUSEYI: The first thing
that we'd notice is nothing.
300
00:17:30,783 --> 00:17:35,720
Things would seem very normal,
but then they wouldn't.
301
00:17:35,821 --> 00:17:40,558
There would be nothing curving
space where Earth is located,
302
00:17:40,659 --> 00:17:43,795
and so Earth would take off
in a straight line,
303
00:17:43,896 --> 00:17:46,464
moving at the same speed at
which it orbits the sun.
304
00:17:46,565 --> 00:17:52,236
And things will get cold
and lonely really, really fast.
305
00:17:54,006 --> 00:17:55,406
ROWE:
According to Albert Einstein,
306
00:17:55,507 --> 00:17:59,143
our skies would go dark, and
the earth would be flung into
307
00:17:59,244 --> 00:18:02,080
deep space at exactly
the same time.
308
00:18:03,782 --> 00:18:07,085
It's a foundation of
his famous Theory of Relativity,
309
00:18:07,186 --> 00:18:11,022
still the most complete theory
of how our universe works.
310
00:18:12,491 --> 00:18:14,358
PONTZEN: Einstein's theory of
relativity has been
311
00:18:14,460 --> 00:18:15,927
a fantastic theory.
312
00:18:16,028 --> 00:18:19,664
It explains so many things
for us, including gravity.
313
00:18:19,765 --> 00:18:21,966
But when we look out
at the universe,
314
00:18:22,067 --> 00:18:25,069
there are many mysteries, there
are things that are quite hard
315
00:18:25,170 --> 00:18:26,137
to explain.
316
00:18:28,474 --> 00:18:30,541
ROWE: At the top of the list --
317
00:18:30,642 --> 00:18:33,010
The mystery
of our expanding universe.
318
00:18:35,848 --> 00:18:39,083
There is something pushing
outward that is
319
00:18:39,184 --> 00:18:43,554
making that expansion rate
ever and ever faster.
320
00:18:43,655 --> 00:18:46,924
ROWE: Astronomers call this
something dark energy.
321
00:18:49,328 --> 00:18:53,831
It accounts for 70% of the total
energy in the universe.
322
00:18:57,102 --> 00:19:00,004
Einstein's models of
the universe need dark energy
323
00:19:00,105 --> 00:19:02,907
to work, but we have no idea
324
00:19:03,008 --> 00:19:04,709
what it is.
325
00:19:06,478 --> 00:19:09,847
Dark energy is not something
we actually understand.
326
00:19:09,948 --> 00:19:12,150
It's kind of a placeholder term
327
00:19:12,251 --> 00:19:14,218
for something
we don't understand.
328
00:19:14,319 --> 00:19:17,889
And so people naturally are
looking for better theories,
329
00:19:17,990 --> 00:19:20,291
theories that are a bit like
Einstein's theory
330
00:19:20,392 --> 00:19:22,860
but just go that bit further
and explain
331
00:19:22,961 --> 00:19:26,531
some of these things that
we don't currently understand.
332
00:19:26,632 --> 00:19:30,201
ROWE: One way to excise
dark energy
333
00:19:30,302 --> 00:19:31,969
is with a new theory of gravity,
334
00:19:33,438 --> 00:19:35,806
one where the speed of
gravitational waves
335
00:19:35,908 --> 00:19:39,143
is different
from the speed of light.
336
00:19:39,244 --> 00:19:40,511
TREMBLAY:
There are some so-called
337
00:19:40,612 --> 00:19:42,280
non-Einsteinian theories for
338
00:19:42,381 --> 00:19:45,383
the structure of spacetime
itself that don't actually
339
00:19:45,484 --> 00:19:46,851
require dark energy.
340
00:19:46,952 --> 00:19:49,654
For example, if gravity
doesn't propagate through
341
00:19:49,755 --> 00:19:52,757
spacetime at the same speed
that light does,
342
00:19:52,858 --> 00:19:55,326
you could find models
that don't actually require
343
00:19:55,427 --> 00:19:58,930
dark energy -- it could be
a clean, simple, albeit very,
344
00:19:59,031 --> 00:20:02,133
very profound solution
to this underlying problem.
345
00:20:04,203 --> 00:20:06,204
ROWE:
In order to overthrow Einstein
346
00:20:06,305 --> 00:20:07,672
and eliminate dark energy,
347
00:20:07,773 --> 00:20:11,442
the speeds of light
and gravity must be different.
348
00:20:12,911 --> 00:20:14,745
We know the speed of light.
349
00:20:14,846 --> 00:20:18,349
So how do we test
the speed of gravity?
350
00:20:20,118 --> 00:20:21,953
In order to test
the speed of gravity,
351
00:20:22,054 --> 00:20:24,088
you need to have a system that
emits both
352
00:20:24,189 --> 00:20:26,123
gravitational waves and light.
353
00:20:28,227 --> 00:20:30,895
ROWE: The colliding
neutron stars detected by LIGO
354
00:20:30,996 --> 00:20:33,731
in 2017 are part of
the solution.
355
00:20:35,467 --> 00:20:38,436
The collision released
a flash of light,
356
00:20:38,537 --> 00:20:40,805
along with a burst of
gravitational waves.
357
00:20:45,577 --> 00:20:49,280
But the universe
threw a curveball.
358
00:20:49,381 --> 00:20:52,450
The light signal arrived
1.7 seconds
359
00:20:52,551 --> 00:20:55,786
after the gravitational wave
signal.
360
00:20:55,887 --> 00:20:57,722
Does that mean
gravitational waves
361
00:20:57,823 --> 00:20:59,790
travel slightly faster
than light?
362
00:21:02,361 --> 00:21:05,463
Albert Einstein predicted
that gravitational waves
363
00:21:05,564 --> 00:21:07,398
would move
at the speed of light.
364
00:21:07,499 --> 00:21:10,167
So what if Albert Einstein
was wrong?
365
00:21:10,269 --> 00:21:11,902
I know, sounds crazy, right?
366
00:21:12,004 --> 00:21:15,006
That's like almost as crazy as
me being wrong, right?
367
00:21:15,107 --> 00:21:18,876
But if Einstein was wrong,
that's one thing.
368
00:21:18,977 --> 00:21:21,946
But a bigger problem is that
we'd have to rethink
369
00:21:22,047 --> 00:21:23,247
our physics.
370
00:21:25,517 --> 00:21:26,584
ROWE: Before we do that,
371
00:21:26,685 --> 00:21:29,153
let's take a closer look
at the neutron star
372
00:21:29,254 --> 00:21:30,488
collision site.
373
00:21:30,589 --> 00:21:31,989
[explosion blasts]
374
00:21:32,090 --> 00:21:34,925
It's surrounded by a shroud
of gas and dust.
375
00:21:36,495 --> 00:21:39,363
Light is made of particles
called photons,
376
00:21:39,464 --> 00:21:42,667
which scatter when
they hit obstacles.
377
00:21:42,768 --> 00:21:46,203
But gravitational waves
pass through anything.
378
00:21:47,472 --> 00:21:50,241
OLUSEYI: They pass right through
everything like it's not there.
379
00:21:50,342 --> 00:21:51,909
Light, on the other hand,
380
00:21:52,010 --> 00:21:55,246
was slowed down by
interactions with that matter.
381
00:21:55,347 --> 00:21:57,481
It didn't just
escape immediately
382
00:21:57,582 --> 00:21:59,884
like the gravitational wave
signal did.
383
00:22:01,653 --> 00:22:03,854
ROWE: The debris gave
the gravitational waves
384
00:22:03,955 --> 00:22:07,258
a head start by slowing
the light.
385
00:22:07,359 --> 00:22:10,127
So gravitational waves
and light do,
386
00:22:10,228 --> 00:22:13,230
in fact,
travel at the same speed.
387
00:22:13,298 --> 00:22:14,665
Einstein was right.
388
00:22:16,601 --> 00:22:19,403
PONTZEN: This one event ruled
out the other theories of
389
00:22:19,504 --> 00:22:21,939
gravity that are competing
with Einstein's theory,
390
00:22:22,040 --> 00:22:25,042
things that people have been
working on all their life
391
00:22:25,143 --> 00:22:27,244
and overnight, it's gone.
392
00:22:29,114 --> 00:22:30,815
ROWE: Thanks
to gravitational waves,
393
00:22:30,916 --> 00:22:34,618
dark energy remains our best
explanation for why
394
00:22:34,720 --> 00:22:37,321
the universe's expansion
is accelerating.
395
00:22:38,824 --> 00:22:41,592
Maybe dark energy isn't what
we think it is, and maybe
396
00:22:41,693 --> 00:22:43,194
tomorrow, or maybe next year,
397
00:22:43,295 --> 00:22:44,862
or maybe next decade
or next century,
398
00:22:44,963 --> 00:22:49,133
we will discover that.
- Gravitational waves are a huge
399
00:22:49,234 --> 00:22:52,603
step forward in our effort to
understand the universe,
400
00:22:52,704 --> 00:22:54,238
and I mean everything.
401
00:22:54,373 --> 00:22:57,475
Space, time, matter,
dark energy.
402
00:22:57,576 --> 00:23:00,978
We have a completely
new universe to view now.
403
00:23:03,749 --> 00:23:05,483
ROWE:
Now astronomers want to use
404
00:23:05,584 --> 00:23:08,552
gravitational waves
to answer another mystery.
405
00:23:10,155 --> 00:23:14,358
What happens when supermassive
black holes collide?
406
00:23:26,004 --> 00:23:30,708
ROWE: We first detected
gravitational waves in 2015.
407
00:23:30,809 --> 00:23:33,444
Since then,
they've revealed colliding
408
00:23:33,545 --> 00:23:35,913
black holes across the universe.
409
00:23:38,116 --> 00:23:40,184
Prior to LIGO going online,
410
00:23:40,285 --> 00:23:43,821
we never witnessed black hole
collisions directly,
411
00:23:43,922 --> 00:23:47,358
but now that we can witness
them with our observatories,
412
00:23:47,459 --> 00:23:50,294
we're finding them
pretty regularly.
413
00:23:50,395 --> 00:23:53,264
We're seeing gravitational
waves come
414
00:23:53,365 --> 00:23:55,433
across the LIGO experiment
415
00:23:55,534 --> 00:23:57,368
left and right.
416
00:23:57,469 --> 00:24:00,204
ROWE: But LIGO has only been
listening for gravitational
417
00:24:00,305 --> 00:24:02,006
waves from black holes
418
00:24:02,107 --> 00:24:04,475
on the smaller end
of the cosmic scale.
419
00:24:06,044 --> 00:24:09,847
When we look at the cosmic zoo
of black holes out there,
420
00:24:09,948 --> 00:24:14,285
we find small ones weighing,
you know, 10, maybe 30 times as
421
00:24:14,386 --> 00:24:18,022
much as the sun, and then large
all the way up to extra-large
422
00:24:18,123 --> 00:24:19,056
going from, like, a million
423
00:24:19,157 --> 00:24:20,858
to a billion times
as much as the sun.
424
00:24:22,327 --> 00:24:24,628
ROWE:
These supermassive black holes
425
00:24:24,729 --> 00:24:27,531
lurk at the hearts of galaxies.
426
00:24:27,632 --> 00:24:31,035
When Galaxies merge,
supermassive black holes
427
00:24:31,136 --> 00:24:33,304
should merge, too.
428
00:24:37,108 --> 00:24:39,543
But even though we see
galaxies colliding
429
00:24:39,644 --> 00:24:40,644
across the universe,
430
00:24:40,745 --> 00:24:44,982
we've never seen two
supermassive black holes
431
00:24:45,083 --> 00:24:47,918
collide, because they have too
432
00:24:48,019 --> 00:24:51,322
much orbital energy to get
close enough to merge.
433
00:24:55,994 --> 00:25:00,064
OLUSEYI: That orbital energy
has to go somewhere,
434
00:25:00,165 --> 00:25:03,100
and what supermassive black
holes do is they throw out
435
00:25:03,201 --> 00:25:06,203
stars that are around
the core of the galaxy.
436
00:25:06,304 --> 00:25:09,640
But when they get sufficiently
close, there are just no more
437
00:25:09,741 --> 00:25:11,175
stars to throw out,
438
00:25:11,276 --> 00:25:14,645
and so the idea is,
they can't merge.
439
00:25:14,746 --> 00:25:15,713
So there's a problem.
440
00:25:15,814 --> 00:25:19,049
How is it that they managed
to bridge that gap
441
00:25:19,150 --> 00:25:21,218
and finally spiral in?
442
00:25:21,319 --> 00:25:23,354
The only way to
understand if supermassive
443
00:25:23,455 --> 00:25:25,523
black holes merge is by looking
444
00:25:25,624 --> 00:25:28,626
at their gravitational
wave signal.
445
00:25:28,727 --> 00:25:30,794
ROWE:
Two supermassive black holes
446
00:25:30,896 --> 00:25:34,498
merging should release a burst
of gravitational waves
447
00:25:34,566 --> 00:25:36,400
millions of times more powerful
448
00:25:36,501 --> 00:25:38,802
than a stellar mass
black hole merger.
449
00:25:41,606 --> 00:25:43,941
But LIGO won't hear a thing.
450
00:25:45,176 --> 00:25:47,311
The problem with using LIGO
to detect the merger
451
00:25:47,412 --> 00:25:50,614
of supermassive black holes is
actually a scale of time.
452
00:25:54,119 --> 00:25:57,321
One wave, as these things move
around each other very slowly,
453
00:25:57,422 --> 00:26:02,259
would take over 10 years
to go by, just one wave.
454
00:26:02,360 --> 00:26:04,495
MINGARELLI: In order to detect
a gravitational wave with
455
00:26:04,596 --> 00:26:05,796
periods of decades,
456
00:26:05,897 --> 00:26:09,733
you also need an experiment
that can be extremely stable
457
00:26:09,834 --> 00:26:11,068
over that amount of time.
458
00:26:12,971 --> 00:26:15,439
ROWE:
Vibrations from earthquakes,
459
00:26:15,540 --> 00:26:17,408
weather, or even nearby traffic
460
00:26:17,509 --> 00:26:21,545
prevent LIGO from listening for
a decade, just to hear one wave.
461
00:26:23,848 --> 00:26:26,717
But there may be another way to
462
00:26:26,818 --> 00:26:30,521
detect gravitational waves
from supermassive black holes,
463
00:26:30,622 --> 00:26:35,492
using a strange type of dead
star called a pulsar.
464
00:26:35,594 --> 00:26:38,996
A pulsar is a kind of
465
00:26:39,097 --> 00:26:42,166
neutron star
that is rapidly spinning
466
00:26:42,267 --> 00:26:45,603
and has a beam of radiation
that makes
467
00:26:45,737 --> 00:26:48,372
wide circles across the sky.
468
00:26:48,473 --> 00:26:52,710
And when that flash of circle
washes over the planet Earth,
469
00:26:52,811 --> 00:26:55,145
we get a little beep,
a little beep.
470
00:26:55,246 --> 00:26:58,248
We get pulses of radiation,
hence pulsar.
471
00:27:00,418 --> 00:27:03,253
ROWE: Pulsars are the best
timekeepers in the universe,
472
00:27:04,589 --> 00:27:09,159
but passing gravitational
waves make them miss a beat.
473
00:27:09,260 --> 00:27:11,996
THALLER: What if we noticed that
the frequency of a pulsar was
474
00:27:12,097 --> 00:27:14,298
shifting very, very slowly,
475
00:27:14,399 --> 00:27:17,434
year to year to year,
over 10 years or more,
476
00:27:17,535 --> 00:27:21,572
just slightly getting a little
bit longer as space itself was
477
00:27:21,673 --> 00:27:23,340
changing between us
and the pulsar?
478
00:27:25,944 --> 00:27:28,379
ROWE: By monitoring
dozens of pulsars,
479
00:27:28,480 --> 00:27:31,181
Chiara Mingarelli
and a team of astronomers
480
00:27:31,282 --> 00:27:36,453
have created a galaxy-sized
gravitational wave detector.
481
00:27:36,554 --> 00:27:42,326
It's called
a pulsar timing array.
482
00:27:42,427 --> 00:27:45,863
You can really look for
deviations in those arrival
483
00:27:45,964 --> 00:27:47,331
times over decades,
484
00:27:47,432 --> 00:27:50,901
almost like a tsunami warning
system to show you when
485
00:27:51,002 --> 00:27:53,837
a gravitational wave
is passing by.
486
00:27:56,341 --> 00:27:58,509
ROWE: After 12 years,
the team detected
487
00:27:58,610 --> 00:28:01,445
the same change
in a number of pulsars.
488
00:28:03,348 --> 00:28:04,615
MINGARELLI:
These pulsars are all
489
00:28:04,716 --> 00:28:06,784
thousands of light-years apart.
490
00:28:06,851 --> 00:28:07,818
If you think about it,
491
00:28:07,919 --> 00:28:11,255
it's difficult to make
a signal that's the same
492
00:28:11,356 --> 00:28:12,956
in all of these pulsars.
493
00:28:13,058 --> 00:28:16,326
This has to be this common
signal from something like
494
00:28:16,428 --> 00:28:18,696
a gravitational wave event.
495
00:28:21,733 --> 00:28:24,468
ROWE: The signal the team
detected wasn't created
496
00:28:24,569 --> 00:28:27,938
by just two supermassive
black holes colliding.
497
00:28:29,441 --> 00:28:33,811
It's evidence of gravitational
waves from hundreds of pairs of
498
00:28:33,912 --> 00:28:35,846
supermassive black holes,
499
00:28:35,947 --> 00:28:38,682
all in different stages
of merging.
500
00:28:41,052 --> 00:28:44,688
Because it takes so long for
one of these individual
501
00:28:44,789 --> 00:28:48,492
binary systems to merge,
there could be thousands,
502
00:28:48,560 --> 00:28:52,196
if not millions, of these
signals all being emitted at
503
00:28:52,297 --> 00:28:54,231
the same time, all of them.
504
00:28:54,332 --> 00:28:56,600
They all create this
gravitational wave background
505
00:28:56,701 --> 00:28:59,303
that we're just starting to see
the first signs of now.
506
00:29:02,474 --> 00:29:05,008
ROWE: Astronomers predict
this gravitational
507
00:29:05,076 --> 00:29:07,711
wave background fills
our universe.
508
00:29:09,581 --> 00:29:12,216
If the signal the team
detected is confirmed,
509
00:29:12,317 --> 00:29:16,286
it's proof that supermassive
black holes do merge.
510
00:29:18,089 --> 00:29:21,825
The next step is to observe
that as it happens.
511
00:29:23,261 --> 00:29:25,996
MINGARELLI: It would be a dream
to see two supermassive
512
00:29:26,097 --> 00:29:27,297
black holes merging,
513
00:29:27,398 --> 00:29:30,134
emitting gravitational waves,
and also being able to point
514
00:29:30,235 --> 00:29:33,470
a telescope at them and to see
the physics of how they merge.
515
00:29:34,939 --> 00:29:37,608
ROWE: Gravitational waves
reveal the hidden workings
516
00:29:37,709 --> 00:29:39,843
of the cosmos.
517
00:29:39,944 --> 00:29:43,213
They reach the farthest
corners of our universe.
518
00:29:44,549 --> 00:29:47,251
Now, astronomers are
using gravitational
519
00:29:47,352 --> 00:29:49,753
waves to look back in time.
520
00:29:51,055 --> 00:29:53,423
They'll let us see
all the way back
521
00:29:53,525 --> 00:29:55,359
to the earliest moments
of our Big Bang.
522
00:29:56,528 --> 00:29:57,961
[explosion blasts]
523
00:30:15,980 --> 00:30:18,315
ROWE: 13.8 billion years ago,
524
00:30:20,285 --> 00:30:22,452
the universe sparks into life.
525
00:30:24,255 --> 00:30:28,258
The tiny speck of energy
expands and cools.
526
00:30:28,359 --> 00:30:33,664
The infant cosmos is a fog of
tiny particles of matter.
527
00:30:33,765 --> 00:30:38,969
Over time, the particles form
atoms of hydrogen and helium.
528
00:30:40,438 --> 00:30:44,074
The fog clears, and the first
light races across
529
00:30:44,175 --> 00:30:45,642
the universe.
530
00:30:45,743 --> 00:30:49,646
We call that light the cosmic
microwave background.
531
00:30:50,849 --> 00:30:52,649
The cosmic microwave
background is simply
532
00:30:52,750 --> 00:30:54,551
the most distant light
we can see.
533
00:30:54,652 --> 00:30:57,621
So, looking at it give us
baby pictures of our universe
534
00:30:57,722 --> 00:31:00,424
the way it looked
400,000 years after a big bang.
535
00:31:02,193 --> 00:31:04,695
ROWE: What happened before
these baby pictures
536
00:31:04,796 --> 00:31:06,997
remains a mystery.
537
00:31:08,199 --> 00:31:11,001
The leading theory is that
in the very first second
538
00:31:11,102 --> 00:31:12,836
of the Big Bang,
539
00:31:12,937 --> 00:31:15,572
our infant universe
had a growth spurt.
540
00:31:18,376 --> 00:31:21,211
Scientists call this
idea inflation.
541
00:31:22,380 --> 00:31:26,316
In a billionth of a billionth of
a billionth of a second,
542
00:31:26,417 --> 00:31:30,287
our universe grew a billion,
billion, billion,
543
00:31:30,388 --> 00:31:33,790
billion, billion, billion
times bigger.
544
00:31:33,892 --> 00:31:37,494
That is the mother of all
growth spurts -- it laid
545
00:31:37,595 --> 00:31:41,565
the foundations for the entire
cosmos that we know today.
546
00:31:49,040 --> 00:31:51,141
ROWE:
Inflation is just a theory,
547
00:31:51,242 --> 00:31:54,845
but there may be a way
to prove it happened.
548
00:31:54,946 --> 00:31:57,481
Scientists think that during
that brief moment of
549
00:31:57,615 --> 00:31:58,849
cosmic expansion,
550
00:31:58,950 --> 00:32:02,786
inflation stretched tiny
fluctuations of gravity.
551
00:32:02,887 --> 00:32:06,823
That is such a violent process
that it actually causes ripples
552
00:32:06,925 --> 00:32:08,191
and distortions in the very
553
00:32:08,293 --> 00:32:10,694
shape and fabric of
space itself,
554
00:32:10,795 --> 00:32:13,096
which we can see today as
gravitational waves.
555
00:32:14,599 --> 00:32:17,434
ROWE: Scientists call these
theoretical ripples through
556
00:32:17,535 --> 00:32:21,004
the early universe primordial
gravitational waves.
557
00:32:22,874 --> 00:32:25,108
SUTTER:
When they were first released,
558
00:32:25,209 --> 00:32:27,678
these were deafening.
559
00:32:27,779 --> 00:32:30,747
But in the billions of years
since, our universe has grown
560
00:32:30,848 --> 00:32:32,282
bigger and colder,
561
00:32:32,383 --> 00:32:35,252
and these gravitational waves
have diluted
562
00:32:35,353 --> 00:32:38,655
so that they barely even
exist today.
563
00:32:38,756 --> 00:32:43,260
ROWE: Scientists searched for
signs of these very weak,
564
00:32:43,361 --> 00:32:46,029
primordial gravitational waves
in the cosmic
565
00:32:46,130 --> 00:32:48,365
microwave background.
566
00:32:48,466 --> 00:32:50,934
And in 2014,
567
00:32:51,035 --> 00:32:54,604
a teen, using their
purpose-built microwave array
568
00:32:54,706 --> 00:32:56,907
in Antarctica called BICEP,
569
00:32:57,008 --> 00:32:59,643
found a strange
swirling pattern.
570
00:32:59,744 --> 00:33:03,947
SUTTER: When they saw those
swirls, they saw those patterns,
571
00:33:04,048 --> 00:33:05,082
they thought they had seen
572
00:33:05,183 --> 00:33:08,185
the signature of primordial
gravitational waves.
573
00:33:08,286 --> 00:33:11,955
Now this is really
the conclusive
574
00:33:12,056 --> 00:33:15,058
evidence that inflation
had to have happened.
575
00:33:15,159 --> 00:33:18,528
ROWE: The results were exciting,
576
00:33:18,629 --> 00:33:21,498
but there was a glitch.
577
00:33:21,599 --> 00:33:23,567
This amazement lasted
578
00:33:23,634 --> 00:33:28,572
for a few months until cracks
started appearing in this,
579
00:33:28,673 --> 00:33:30,173
and gradually, it all collapsed.
580
00:33:33,144 --> 00:33:34,778
ROWE: The signal,
thought to be proof of
581
00:33:34,879 --> 00:33:39,082
primordial gravitational waves
and the theory of inflation,
582
00:33:39,183 --> 00:33:41,985
turned out to be a case of
mistaken identity.
583
00:33:45,656 --> 00:33:47,691
SUTTER: As this light
from the ancient universe,
584
00:33:47,792 --> 00:33:50,494
from the cosmic microwave
background, travels
585
00:33:50,595 --> 00:33:53,196
through the universe, it had
to travel through dust
586
00:33:53,297 --> 00:33:58,468
before reaching our detectors,
and the dust itself can affect
587
00:33:58,569 --> 00:34:01,271
the light and mimic what
588
00:34:01,372 --> 00:34:03,707
the primordial gravitational
waves can do.
589
00:34:05,510 --> 00:34:07,878
ROWE: The primordial
gravitational wave signal
590
00:34:07,979 --> 00:34:11,214
turned out to be
mainly clouds of dust
591
00:34:11,315 --> 00:34:12,783
floating through space.
592
00:34:15,386 --> 00:34:17,754
That's how BICEP bit the dust.
593
00:34:19,590 --> 00:34:21,391
ROWE: BICEP failed to detect
594
00:34:21,492 --> 00:34:24,594
primordial gravitational waves.
595
00:34:24,695 --> 00:34:27,097
Can LIGO do any better?
596
00:34:27,198 --> 00:34:30,967
OLUSEYI: Unfortunately,
LIGO can't help us
597
00:34:31,069 --> 00:34:33,770
in observing primordial
gravitational waves.
598
00:34:33,871 --> 00:34:35,939
It can't even observe
supermassive black holes
599
00:34:36,040 --> 00:34:37,240
at the centers of galaxies.
600
00:34:37,341 --> 00:34:39,509
It is designed to
observe in a particular
601
00:34:39,610 --> 00:34:41,278
frequency range.
602
00:34:41,379 --> 00:34:44,181
SUTTER:
Primordial gravitational waves
603
00:34:44,282 --> 00:34:46,349
are at such a low frequency in
604
00:34:46,451 --> 00:34:48,251
such a low amplitude
605
00:34:48,352 --> 00:34:52,989
that there is no hope of LIGO
being able to detect them.
606
00:34:55,560 --> 00:34:58,228
ROWE: But scientists hope
that an ambitious project
607
00:34:58,329 --> 00:35:00,197
called LISA will.
608
00:35:01,732 --> 00:35:05,268
Not on Earth, but from
30 million miles above.
609
00:35:07,205 --> 00:35:10,474
LISA is like LIGO,
610
00:35:10,575 --> 00:35:12,476
but bigger and in space.
611
00:35:16,314 --> 00:35:17,914
ROWE: LISA,
612
00:35:18,015 --> 00:35:22,052
or the Laser Interferometer
Space Antenna, will be a system
613
00:35:22,153 --> 00:35:26,890
of three satellites arranged in
a giant triangular formation,
614
00:35:26,991 --> 00:35:29,893
1.5 million miles apart.
615
00:35:29,994 --> 00:35:32,262
PLAIT: If a gravitational
wave passes through them
616
00:35:32,363 --> 00:35:33,563
and changes that distance,
617
00:35:33,664 --> 00:35:36,066
they can detect that -- because
the satellites are so much
618
00:35:36,167 --> 00:35:39,436
farther apart,
a very low frequency wave
619
00:35:39,537 --> 00:35:40,937
can make a detectable change.
620
00:35:41,038 --> 00:35:44,875
LIGO wouldn't be able to see
that, but LISA could.
621
00:35:44,976 --> 00:35:47,277
ROWE: As well as listening
for low frequency
622
00:35:47,378 --> 00:35:50,514
gravitational wave sources,
like supermassive black
623
00:35:50,615 --> 00:35:51,948
hole mergers,
624
00:35:52,049 --> 00:35:55,318
LISA will listen for
primordial gravitational
625
00:35:55,419 --> 00:35:58,355
waves from the dawn of time.
626
00:35:58,456 --> 00:35:59,523
If it detects them,
627
00:35:59,624 --> 00:36:03,760
we will know that the infant
universe inflated.
628
00:36:04,929 --> 00:36:08,131
Inflation has explained
almost everything
629
00:36:08,232 --> 00:36:10,767
we measure in modern cosmology.
630
00:36:10,868 --> 00:36:12,636
It's an incredibly
successful theory.
631
00:36:12,737 --> 00:36:15,305
The icing on the cake
would be if we could
632
00:36:15,406 --> 00:36:17,974
also discover these
gravitational waves
633
00:36:18,075 --> 00:36:21,411
that it's supposed
to have created.
634
00:36:22,880 --> 00:36:25,982
ROWE: From the Big Bang to
the most massive black holes,
635
00:36:27,084 --> 00:36:30,487
the universe talks to us
using gravitational waves.
636
00:36:32,757 --> 00:36:37,494
Just like with telescopes, we're
using gravitational waves to
637
00:36:37,595 --> 00:36:39,629
look at different types
of objects --
638
00:36:39,730 --> 00:36:44,300
Neutron star mergers and black
hole mergers -- and learn more
639
00:36:44,368 --> 00:36:45,969
about the universe around us.
640
00:36:48,372 --> 00:36:49,639
ROWE: They could even reveal
641
00:36:49,740 --> 00:36:53,043
the most elusive substance
in the universe --
642
00:36:53,144 --> 00:36:55,045
Dark matter.
643
00:36:55,146 --> 00:36:57,881
SUTTER: If anything's gonna
help us understand
644
00:36:57,982 --> 00:36:59,216
the nature of dark matter,
645
00:36:59,317 --> 00:37:01,651
it might just be
gravitational waves.
646
00:37:11,195 --> 00:37:12,562
ROWE: Across the universe,
647
00:37:12,663 --> 00:37:15,832
an invisible substance holds
galaxies together.
648
00:37:15,900 --> 00:37:20,070
Without it,
they would fly apart.
649
00:37:20,171 --> 00:37:23,974
THALLER: The Milky Way
should've dispersed long ago,
650
00:37:24,075 --> 00:37:26,142
and the Magellanic clouds
right in front of us are
651
00:37:26,244 --> 00:37:27,577
exactly the same.
652
00:37:27,678 --> 00:37:29,479
These things should be
just shedding stars
653
00:37:29,580 --> 00:37:32,215
left and right as they fly off
this rotating galaxy.
654
00:37:32,316 --> 00:37:34,751
Instead, they're not.
They're holding together.
655
00:37:34,852 --> 00:37:37,320
There are motions in the stars
that we just cannot
656
00:37:37,421 --> 00:37:39,723
account for unless there's
something holding
657
00:37:39,824 --> 00:37:40,790
the whole thing together.
658
00:37:42,560 --> 00:37:45,695
ROWE: We call this mysterious
substance dark matter.
659
00:37:45,796 --> 00:37:50,267
It doesn't interact with
light, so we can't see it.
660
00:37:50,368 --> 00:37:52,335
But we cannot ignore it.
661
00:37:54,305 --> 00:37:57,741
From the motions of stars
inside of galaxies to
662
00:37:57,842 --> 00:38:00,610
the motions of galaxies
inside of clusters
663
00:38:00,711 --> 00:38:04,481
to the very structure of
the universe itself,
664
00:38:04,582 --> 00:38:08,718
we see evidence for dark
matter everywhere we look.
665
00:38:11,389 --> 00:38:13,690
ROWE:
We think dark matter makes up
666
00:38:13,791 --> 00:38:17,761
85% of the matter
in the universe.
667
00:38:17,862 --> 00:38:22,065
But because we can't see
dark matter with telescopes,
668
00:38:22,166 --> 00:38:23,867
we know very little about it.
669
00:38:25,636 --> 00:38:27,904
ESQUIVE:
While we know that it's there,
670
00:38:28,005 --> 00:38:31,541
we haven't actually answered
the question of what it is
671
00:38:31,642 --> 00:38:35,979
or how it interacts or why it's
there or how it's created.
672
00:38:36,080 --> 00:38:37,847
So you have to be
really creative
673
00:38:37,948 --> 00:38:39,249
if you want to go after
this stuff
674
00:38:39,350 --> 00:38:42,185
and really understand what's
it made out of?
675
00:38:45,556 --> 00:38:48,258
ROWE: One creative theory
suggests that black holes
676
00:38:48,359 --> 00:38:50,560
make up dark matter,
677
00:38:50,661 --> 00:38:54,564
not the regular stellar mass
black holes that LIGO detects,
678
00:38:56,000 --> 00:38:58,401
or the supermassive black
holes that
679
00:38:58,502 --> 00:39:00,704
lurk at the center of galaxies
680
00:39:00,805 --> 00:39:05,442
but tiny, primordial black
holes born during the period of
681
00:39:05,576 --> 00:39:09,412
rapid expansion in the first
moments of the Big Bang.
682
00:39:10,881 --> 00:39:13,350
Primordial black holes could be
683
00:39:13,451 --> 00:39:16,920
potential explanations
for what we call dark matter.
684
00:39:17,021 --> 00:39:19,222
And if there's enough of them,
they can hold an entire
685
00:39:19,323 --> 00:39:21,057
galaxy together.
686
00:39:21,158 --> 00:39:24,961
ROWE: We don't know if
primordial black holes exist,
687
00:39:25,062 --> 00:39:30,033
but gravitational waves
could change that.
688
00:39:30,167 --> 00:39:32,535
PONTZEN: When you form
a primordial black hole,
689
00:39:32,636 --> 00:39:35,205
you send out a burst of
gravitational waves
690
00:39:35,306 --> 00:39:38,174
that, in principle, carries on
traveling through the universe,
691
00:39:38,275 --> 00:39:39,809
and you might be able to
detect it
692
00:39:39,910 --> 00:39:41,177
still today.
693
00:39:41,278 --> 00:39:43,880
TREMBLAY: The problem is that
these things would have emitted
694
00:39:43,981 --> 00:39:46,149
gravitational waves at
a frequency that is not
695
00:39:46,250 --> 00:39:47,617
detectable by LIGO.
696
00:39:47,718 --> 00:39:50,987
And so it's very hard to
discern whether or not they
697
00:39:51,088 --> 00:39:54,357
are plentiful enough to
actually serve as a compelling
698
00:39:54,458 --> 00:39:55,458
dark matter candidate.
699
00:39:58,028 --> 00:40:00,430
ROWE: If primordial
black holes do exist,
700
00:40:00,531 --> 00:40:03,633
they still might not explain
all the dark matter in
701
00:40:03,734 --> 00:40:05,335
the universe.
702
00:40:05,436 --> 00:40:07,737
They might be working
with another type
703
00:40:07,838 --> 00:40:10,407
of dark matter to hold
galaxies together.
704
00:40:11,809 --> 00:40:14,878
The upcoming LISA mission
may fill in the blanks.
705
00:40:16,514 --> 00:40:18,748
SUTTER: What we call dark matter
could be simple.
706
00:40:18,849 --> 00:40:22,452
It could just be made of one
thing that absolutely floods
707
00:40:22,553 --> 00:40:24,687
the universe,
or it can be made of
708
00:40:24,789 --> 00:40:28,291
many different things that
all work together to combine
709
00:40:28,392 --> 00:40:29,893
to make this effect.
710
00:40:29,994 --> 00:40:32,095
Is dark matter all
primordial black holes?
711
00:40:32,196 --> 00:40:34,898
Is it something else that
we haven't thought of yet?
712
00:40:34,999 --> 00:40:38,268
Gravitational waves could
provide those answers.
713
00:40:40,471 --> 00:40:43,706
ROWE: The detection of tiny
gravitational waves generated
714
00:40:43,808 --> 00:40:45,542
by primordial black holes
715
00:40:45,643 --> 00:40:49,879
will be a huge advance in our
understanding of dark matter.
716
00:40:49,980 --> 00:40:51,581
OLUSEYI: With gravitational
wave astronomy,
717
00:40:51,682 --> 00:40:54,918
we're seeing things that
we have never seen before.
718
00:40:55,019 --> 00:40:56,519
So who knows
719
00:40:56,620 --> 00:40:59,088
what we're gonna see as we
continue to look out into space?
720
00:41:01,826 --> 00:41:04,861
MINGARELLI: We've been able
to see dozens of black holes
721
00:41:04,962 --> 00:41:07,597
merge,
two neutron stars merging,
722
00:41:07,698 --> 00:41:10,633
and discovered from
that merger that neutron stars
723
00:41:10,734 --> 00:41:12,735
can make platinum and gold.
724
00:41:15,806 --> 00:41:18,374
From thinking that we would
never be able to see
725
00:41:18,476 --> 00:41:22,712
gravitational waves to seeing
gravitational wave signals
726
00:41:22,813 --> 00:41:25,815
happen on the regular --
It's just crazy.
727
00:41:27,518 --> 00:41:30,720
ROWE: Already,
we've heard epic explosions.
728
00:41:32,289 --> 00:41:35,825
We've identified the brightest
lights in the cosmos,
729
00:41:37,328 --> 00:41:40,497
and we have solved some of
the biggest mysteries
730
00:41:40,598 --> 00:41:42,565
in astronomy.
731
00:41:42,666 --> 00:41:46,069
But that is just the beginning.
732
00:41:46,170 --> 00:41:49,172
THALLER: Right now is
a golden age in astronomy.
733
00:41:49,273 --> 00:41:51,574
Think of the time that you're
living in -- the first detection
734
00:41:51,675 --> 00:41:54,811
of gravitational waves by LIGO
was only a couple of years ago.
735
00:41:54,912 --> 00:41:56,679
You were here of the birth of
736
00:41:56,780 --> 00:41:58,681
this entirely new view of
the universe.
59418
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