how.the.universe.works.s06e01.are.black.holes.real.480p.web.x264.rmteam Subtitles

At 00:00:07,260, Character said: Cosmologists are battling over
the universe's greatest enigma.

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At 00:00:14,260, Character said: Black holes.

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At 00:00:17,130, Character said: We've never seen them.

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At 00:00:19,070, Character said: It's near impossible
to study them.

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At 00:00:21,540, Character said: And their existence
challenges everything

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At 00:00:24,770, Character said: we think we know about space.

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At 00:00:29,210, Character said: The black hole represents
the absolute limits

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At 00:00:31,210, Character said: of what we understand
about nature.

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At 00:00:35,280, Character said: The truth is, we have almost
no idea what these things are

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At 00:00:38,760, Character said: and how they work.

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At 00:00:41,020, Character said: Black holes are at
the very heart of cosmology.

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At 00:00:45,290, Character said: Yet, some scientists question
if they're even real.

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At 00:00:49,370, Character said: Black holes present
lots of paradoxes,

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At 00:00:52,370, Character said: and the simplest way to resolve
the paradoxes would be

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At 00:00:55,510, Character said: if black holes
didn't exist at all.

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At 00:00:59,180, Character said: Solving the mysteries
of black holes

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At 00:01:01,380, Character said: pushes our understanding
of physics

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At 00:01:03,980, Character said: to the edge of reason.

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At 00:01:06,520, Character said: But it's the only way
to discover

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At 00:01:09,590, Character said: if black holes really exist.

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At 00:01:14,320, Character said: Captions by vitac ...
www.Vitac.Com

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At 00:01:17,390, Character said: captions paid for by
discovery communications

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At 00:01:36,550, Character said: Black holes are the monsters
of the universe...

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At 00:01:41,420, Character said: Terrifying cosmic beasts
that devour all they encounter.

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At 00:01:49,290, Character said: But black holes scare scientists
for very different reasons.

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At 00:01:55,630, Character said: They challenge our theories
to the breaking point.

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At 00:01:58,640, Character said: This is at the forefront
of theoretical physics.

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At 00:02:03,510, Character said: When it comes to the
detailed nature of black holes,

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At 00:02:06,910, Character said: it would not surprise me
if we g***t it all wrong.

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At 00:02:15,120, Character said: The science of black holes
is so challenging

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At 00:02:18,660, Character said: that some scientists question
whether they exist at all.

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At 00:02:26,860, Character said: Despite their fearsome
reputation,

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At 00:02:30,600, Character said: we've never actually seen one.

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At 00:02:35,670, Character said: Black holes are everywhere.
They're all over the universe.

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At 00:02:37,940, Character said: They're all throughout
our galaxy.

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At 00:02:39,610, Character said: But that doesn't mean
that they're easy to find.

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At 00:02:42,350, Character said: They're black,
and space is black,

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At 00:02:44,810, Character said: and black-on-black
is kind of hard

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At 00:02:46,780, Character said: to see in a picture of space.

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At 00:02:50,150, Character said: This is paradoxical

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At 00:02:51,560, Character said: because scientists believe
black holes are born

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At 00:02:55,090, Character said: in some of the brightest
explosions in the universe...

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At 00:03:01,160, Character said: rising from the corpses
of detonated stars

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At 00:03:04,900, Character said: many times larger than our sun.

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At 00:03:09,370, Character said: A star that burns
for 10 million years

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At 00:03:12,110, Character said: collapses to form a black hole
in a period of seconds.

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At 00:03:18,110, Character said: As it collapses,

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At 00:03:19,250, Character said: the outer region of the star
hits the core,

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At 00:03:22,250, Character said: triggering a huge explosion...
A supernova.

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At 00:03:31,990, Character said: We see the bang,
but not what's left behind...

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At 00:03:38,470, Character said: a dead core with
the enormous mass of the star

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At 00:03:42,140, Character said: crushed down into
an infinitesimal, tiny area.

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At 00:03:53,950, Character said: From this minuscule
high-mass core,

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At 00:03:57,420, Character said: a black hole is born.

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At 00:04:00,620, Character said: The flow of gravity is so strong
that nothing can escape...

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At 00:04:05,430, Character said: Not even light.

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At 00:04:10,570, Character said: But how can scientists claim
that black holes exist

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At 00:04:13,970, Character said: if we can't even see them?

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At 00:04:21,180, Character said: You could say that about
the existence of the atom.

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At 00:04:23,780, Character said: We knew they had existed
for decades, centuries

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At 00:04:26,650, Character said: before we had actually seen one
in some sort of imaging device.

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At 00:04:31,790, Character said: And so it's the same sort
of thing with black holes.

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At 00:04:35,790, Character said: Just because you can't see it
doesn't mean it's not there.

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At 00:04:38,600, Character said: Not seeing black holes
but knowing they're there

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At 00:04:41,200, Character said: is a possibility,

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At 00:04:42,400, Character said: just like we know
that wind is there,

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At 00:04:44,800, Character said: even though we can't see air.

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At 00:04:49,410, Character said: Air is invisible,
but when the wind blows,

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At 00:04:52,480, Character said: its effects can be measured.

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At 00:04:56,010, Character said: It's the same with black holes.

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At 00:04:57,880, Character said: You just need to know
what to look for.

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At 00:05:02,350, Character said: While they emit
no light themselves,

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At 00:05:04,620, Character said: black holes are tremendous
sources of x-rays,

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At 00:05:07,160, Character said: and that's because as things
get close to a black hole,

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At 00:05:10,030, Character said: they're accelerated
by the gravity,

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At 00:05:12,160, Character said: and they can heat up
to millions of degrees.

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At 00:05:14,760, Character said: Million-degree gas
gives you lots of x-rays.

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At 00:05:20,370, Character said: To find and measure
these telltale x-rays,

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At 00:05:24,370, Character said: scientists turn
to the NuSTAR space telescope.

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At 00:05:30,780, Character said: In 2017, it spots
a burst of x-rays

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At 00:05:34,850, Character said: in a cluster called 47 Tucanae,

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At 00:05:37,920, Character said: at the edge of the milky way.

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At 00:05:42,530, Character said: When scientists analyze
the data,

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At 00:05:45,130, Character said: they realize they're
looking at two objects

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At 00:05:48,200, Character said: orbiting each other
very closely.

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At 00:05:54,340, Character said: All we see is that there's
a star being ripped apart,

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At 00:05:57,670, Character said: and gas is spiraling down to
a very dense, very dark object,

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At 00:06:01,680, Character said: so something weird is going on.

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At 00:06:04,950, Character said: As one of the objects
accretes matter off the other,

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At 00:06:08,020, Character said: it causes it to emit x-rays,

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At 00:06:10,220, Character said: and those x-rays can be used,
then, to trace out the orbits

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At 00:06:13,220, Character said: and, therefore,
extract the mass.

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At 00:06:18,430, Character said: When scientists work out

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At 00:06:20,030, Character said: the size and mass
of the two objects,

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At 00:06:22,570, Character said: they find the first
is the fading corpse

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At 00:06:25,700, Character said: of a sunlike star.

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At 00:06:29,110, Character said: And while the second object
is tiny,

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At 00:06:31,640, Character said: it has the mass of a giant.

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At 00:06:35,450, Character said: Is this an elusive black hole?

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At 00:06:40,050, Character said: What we're talking about here
is an object

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At 00:06:42,120, Character said: that is very massive,
very small, very dense,

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At 00:06:45,590, Character said: with intense gravity.

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At 00:06:48,060, Character said: But it turns out there
are lots of different ways

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At 00:06:50,060, Character said: to create an object like that.

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At 00:06:52,730, Character said: There is another type of
ultra-dense object out there

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At 00:06:55,260, Character said: in the universe,
called a neutron star.

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At 00:07:01,800, Character said: Neutron stars form in the same
way we think black holes form...

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At 00:07:06,280, Character said: When stars die, explode,

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At 00:07:08,680, Character said: but then collapse down
into a tiny ball of matter.

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At 00:07:14,350, Character said: The gravitational attraction
of a neutron star is enormous,

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At 00:07:18,690, Character said: pulling in gas,
dust, and asteroids.

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At 00:07:22,220, Character said: But light can still escape.

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At 00:07:26,230, Character said: Black holes and neutron stars
are kind of cousins,

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At 00:07:29,230, Character said: but in the case
of a neutron star,

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At 00:07:31,100, Character said: it didn't have quite enough mass
to collapse out of control.

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At 00:07:35,040, Character said: So you can sort of think of it
as just barely hanging back

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At 00:07:38,170, Character said: from collapsing
into a black hole.

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At 00:07:42,850, Character said: The tiny object
discovered by NuSTAR

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At 00:07:45,310, Character said: does have enormous mass.

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At 00:07:49,590, Character said: But size and mass alone

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At 00:07:51,920, Character said: are not enough to prove
it's a black hole.

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At 00:07:56,590, Character said: Cosmologists need more evidence.

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At 00:08:00,530, Character said: They can't see black holes,
but is there another way?

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At 00:08:05,070, Character said: What if they could hear them?

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At 00:08:09,540, Character said: Think of two massive cars
colliding... boom!

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