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ROWE: The night sky.

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Countless stars
and the majestic sweep

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of the Milky Way, but beyond
our local neighborhood,

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across the cosmos,
there are over

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two trillion more galaxies.

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THALLER: When we first began
to observe galaxies,

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we collected them
like butterflies.

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Little by little,
we realized that

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they formed a web.

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ROWE: The cosmic web is
the infrastructure that connects

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every corner of the universe.

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You don't know anything
about our universe

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if you don't understand
the cosmic web.

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It feeds galaxies.
It forms galaxies.

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It is made of galaxies.

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ROWE: It's the architect
of everything,

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and our cosmic future
depends on it.

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The cosmic web is one of
the most important parts

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of our universe --
It plays a key role

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in the evolution of the cosmos.

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Without the cosmic web,
there would be no stars,

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no planets, nowhere in
the universe where

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the conditions of life
could exist.

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ROWE: How did the universe go
from a hot soup of gas

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to a cosmic web,
sprinkled with galaxies,

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planets, and us?

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The universe may appear random.

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Two trillion galaxies,
spread across the cosmos.

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But in this cosmic chaos,

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scientists detect water.

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When we first saw that
the universe was full

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of galaxies, it seemed like
overwhelming chaos,

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but it's not --
They're all connected.

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ROWE: Galaxies link up
in a gigantic cosmic network

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spanning the entire universe.

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How this pattern emerged
may be cosmology's

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biggest puzzle.

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In some senses, you don't
understand something

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unless you understand
how it comes into existence

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and how it's formed.

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And galaxies are the basic
building block

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of our universe.

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ROWE: To solve this mystery,
scientists need to go deep,

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to the very edge of
the observable universe,

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and study light from
the first galaxies.

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Chile, 2021.

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Scientists point the VLT,
or Very Large Telescope,

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towards the Hubble
Ultra Deep Field.

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It's a patch of sky
famously photographed

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by the Hubble Space Telescope
in 1995.

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The VLT's power allows
astronomers to see

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much deeper into space.

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Imagine you take
a grain of sand,

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and you put it
on your fingertip,

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and you hold your arm out
like this,

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and you block a part of
the sky looking

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at that grain of sand --
That's the size

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of the Hubble Ultra Deep Field,
and yet it contains

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thousands of galaxies in it.

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ROWE: The telescope stares
at those galaxies

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for 155 hours and picks up
the faintest of glows...

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ancient hydrogen gas
concentrated along a strand

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of space 15 million
lightyears long.

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The filaments are just
one tiny section

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of the cosmic web,
the largest known

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structure in the universe.

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The scale of the cosmic web
is enormous.

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It is, by definition,
the largest thing

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that we can see in our universe.

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ROWE: Today, the cosmic web
is a lattice of filaments,

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linked streams of hydrogen gas

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that form an intergalactic
network spanning

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the entire universe.

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Inside the nodes of
the cosmic web,

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you'll find galaxies
and stars and black holes.

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Along the filaments,
you'll find gas

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that connects these nodes,
and the gas will connect

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to the other galaxies
and clusters of galaxies.

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It's this beautiful
superhighway of

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large cities that are connected
through these filaments.

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BULLOCK:
We can see the cosmic web

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about as far back as
we can look,

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and really, galaxies are
forming along that web

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all the way back.

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ROWE: This cosmic
infrastructure dates back

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to the earliest days
of the universe.

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13.8 billion years ago,

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the universe ignites in
a tiny ball

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of super hot energy.

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It expands and begins to cool.

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Energy transforms
into primitive,

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subatomic particles of matter.

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The heat from the Big Bang
is so intense,

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gravity is
effectively powerless.

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The very early universe was
super hot,

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super energetic,
and regular particles

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of matter were zipping around
so fast

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that not even gravity
could hold them together.

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But regular matter wasn't
the only thing

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in the early universe.

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ROWE: In the background,
gravity is working

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on something else --

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Regular matter's ghostly cousin,

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the invisible substance
known today as dark matter.

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It makes up about 85 percent
of all the matter

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created in the early universe.

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Normal matter and dark matter
both existed

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around the time of the Big Bang,
but they way they played out

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was very different.

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ROWE: Just ten seconds after
the Big Bang,

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the infant universe is
billions of degrees Fahrenheit,

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still far too hot for
regular matter particles

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to clump together, but dark
matter plays by different rules.

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Dark matter isn't affected by
the Big Bang's intense

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radiation in the same way
that regular matter is,

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and so because it's able
to cool,

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it clumps together in a way
that regular matter doesn't.

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ROWE: As dark matter clumps
grow, they exert

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a gravitational pull and begin
to form shadowy structures.

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As soon as the dark matter
gets a foothold,

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we have a place where there's
a bit more stuff,

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then that attracts
more and more dark matter.

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ROWE: 380,000 years after
the Big Bang,

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the intense heat drops
to a few thousand degrees.

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Normal particles of matter
move around more slowly.

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Protons and electrons bind
together and form

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atoms of hydrogen
and helium gas.

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Then gravity from dark matter
starts to work

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on regular matter.

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Before you know it,
you have this very clumpy

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universe with these huge
dark matter halos

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that can now start to draw in
also ordinary matter

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in the form of gas.

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ROWE: A billion-year building
project begins.

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The dark matter clumps
pulled in clouds of gas...

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the foundations of
the cosmic web and the galaxies.

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Just as when you build
a building, you know,

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there's a lot of work that
happens before

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the building goes up,
our universe spent

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a lot of time laying
the groundwork for

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this cosmic web before
it switched on the lights.

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ROWE: The foundations
are complete,

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but the job isn't finished.

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How did those clouds of gas
transform into the greatest

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structure in the universe?

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The secretive dark matter
that brought the gas together

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is also on site,
managing the build.

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It was really the dark matter
that called the shots

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in cosmic clustering,
because it outweighed

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the ordinary stuff by
a big factor.

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In essence, the cosmic web
is made of dark matter.

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Tendrils of material are
stretched out across the cosmos.

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ROWE: As the sprawling structure
builds, its gravitational

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pull strengthens, pulling in
more dark matter.

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The clumps begin to collapse
and shrink down

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into filaments -- these meet
at even more tightly

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packed clusters, creating
a huge, dark scaffold

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that drags in more hydrogen gas.

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BULLOCK: Imagine drops of dew
on a spider web.

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That's like hydrogen blobs
being pulled in

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to dark matter's cosmic web.

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ROWE: After tens of millions
of years of construction,

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strands of gas stretch
across the cosmos.

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Fast forward to now --
The web appears

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in all its star-spangled glory,
lit up with galaxies.

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We know at some point,
stars and galaxies formed.

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The big question is when --
What were the first

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galaxies like?
That's a big mystery.

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ROWE: So how then did the lights
of the cosmos switch on?

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Evidence suggests that as
the universe assembled its web

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of dark matter and hydrogen gas,

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the biggest stars that have
ever lived

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set the cosmos ablaze.

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ROWE: 2018, scientists study
an ancient galaxy,

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the catchily named MACS1149-JD1.

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There, they find some of
the oldest stars

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ever detected.

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This particular galaxy is
exciting, because it's

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forming stars just a very
short time after the Big Bang.

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ROWE: Those stars could hold
clues as to how

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the cosmic web that supports
the universe

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first lit up,
but as astronomers study

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starlight from when
the universe was just

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250 million years old,
they get a shock.

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The stars are not just
made up of hydrogen

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and helium produced
in the Big Bang.

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They also contain what
astronomers call metals.

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Metals in astronomy is
everything heavier

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than hydrogen and helium.

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SUTTER: No matter where it is
on the periodic table,

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if you're not hydrogen
or helium, you are a metal,

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even though that makes no sense.

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If I were king of astronomy,
metals is right out.

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NANCE: The Big Bang only
made hydrogen and helium.

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Anything heavier than that
was churned up in

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the cores of dying stars.

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ROWE: The bright stars of
this ancient galaxy

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dating back to just 250
million years after

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the Big Bang contain chemicals
that were created

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in even earlier stars.

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Some of them seem to be
nearly the age of

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the universe, extremely old,
and yet they contain

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elements that guarantee
they can't have been

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the first generation --
As old as these stars are,

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there must have been something
that came before.

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ROWE: The earlier first
generation of stars

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remains cloaked in mystery.

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00:11:37,397 --> 00:11:39,798
How did the first stars ignite,

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00:11:39,800 --> 00:11:43,401
and did they kickstart
the formation

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of the first galaxies?

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It sounds like a classic
creation myth,

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it's out of the darkness,
out of nothing,

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structure arrived,
and from that structure,

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the galaxies, the lights
in the universe, turned on.

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00:12:02,689 --> 00:12:05,290
ROWE: We've never seen
a first-generation star,

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00:12:05,292 --> 00:12:08,693
but physicists have a theory
of how they formed

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00:12:08,762 --> 00:12:11,296
and what they were like.

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Let's step even further
back in time,

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00:12:14,601 --> 00:12:18,036
to around 100 million years
after the Big Bang.

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The early cosmic web is dark.

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There are no stars
to illuminate it.

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But the universe is ready
for stellar ignition.

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Cooled down after millions
of years of expansion,

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the gas clouds clinging
to the dark matter scaffold

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begin to contract.

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00:12:40,660 --> 00:12:45,430
As the hydrogen gas
clumps together,

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larger clouds form super dense,

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ultra hot cores.

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THALLER: If you can bring
hydrogen together,

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and actually get it hot
and dense enough,

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hydrogen will begin to fuse
into helium.

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There will be a nuclear fusion
reaction going on.

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00:13:01,714 --> 00:13:06,417
ROWE: Simulations suggest that
some gas clouds are

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00:13:06,519 --> 00:13:08,787
hundreds of times the mass
of the sun.

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The stars they produce

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are unlike anything
that exist today.

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So the stars around us today
really top out at masses

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00:13:21,101 --> 00:13:25,036
between let's say 70 to 100
times the mass of our sun.

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00:13:25,104 --> 00:13:28,039
There's nothing larger
than that.

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NANCE: These first stars
were up to 1,000 times

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more massive than the sun,
so if you plopped it

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00:13:34,781 --> 00:13:36,881
in our solar system,
it would extend

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00:13:36,883 --> 00:13:39,717
all the way past Jupiter --
So think about that.

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That is incredibly big.

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00:13:41,754 --> 00:13:44,489
That scale is mind-blowing.

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00:13:46,259 --> 00:13:48,493
ROWE: So what happened to
these stellar behemoths?

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00:13:48,595 --> 00:13:53,198
THALLER: The lifetime of a star
has a lot to do with its mass.

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00:13:53,266 --> 00:13:56,100
The more massive a star is,
the more gravity crushes

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00:13:56,202 --> 00:13:58,803
the interior up to high
temperatures, and it burns

250
00:13:58,872 --> 00:14:02,207
through its nuclear fuel
even faster, so incredibly,

251
00:14:02,209 --> 00:14:05,043
the more mass there is,
the shorter a lifetime

252
00:14:05,111 --> 00:14:07,278
you get for a star.

253
00:14:07,413 --> 00:14:09,681
OLUSEYI: The first generation
of stars are sort of like

254
00:14:09,683 --> 00:14:13,952
the rappers and rock stars of
the universe.

255
00:14:14,053 --> 00:14:16,054
They live fast, they die young.

256
00:14:18,892 --> 00:14:21,392
ROWE: First generation stars
didn't live long enough

257
00:14:21,394 --> 00:14:24,929
to form complex galaxies,
but they did set

258
00:14:24,998 --> 00:14:26,965
the process in motion.

259
00:14:27,033 --> 00:14:31,269
The lives of the first stars
may have been rock and roll,

260
00:14:31,271 --> 00:14:34,539
but their explosive deaths
and supernovas

261
00:14:34,607 --> 00:14:38,376
pump the universe full
of heavy metal.

262
00:14:38,378 --> 00:14:42,747
THALLER: In the galaxy today,
we see a supernova

263
00:14:42,749 --> 00:14:45,450
maybe every couple of years,
close to us every

264
00:14:45,452 --> 00:14:48,386
couple of decades -- this must
have been a fireworks show,

265
00:14:48,488 --> 00:14:52,957
giant supernovas going off
all the time, all around you.

266
00:14:53,059 --> 00:14:58,129
OLUSEYI: That act of destruction
is actually an act of creation.

267
00:14:58,231 --> 00:15:01,299
What a star does in its core
is it creates

268
00:15:01,368 --> 00:15:03,568
heavier elements
from lighter elements.

269
00:15:03,570 --> 00:15:07,705
THALLER: That first generation
of stars must have been

270
00:15:07,741 --> 00:15:10,675
absolutely incredible,
simply exploding

271
00:15:10,677 --> 00:15:14,178
so quickly and unloading all of
this wonderful new chemistry

272
00:15:14,180 --> 00:15:16,381
into the galaxy.

273
00:15:16,383 --> 00:15:20,118
ROWE: 200 million years after
the Big Bang,

274
00:15:20,186 --> 00:15:23,688
the remains of the first stars
flood the interstellar medium

275
00:15:23,790 --> 00:15:28,259
with heavier elements,
like carbon, oxygen,

276
00:15:28,261 --> 00:15:30,295
silicon, and iron,

277
00:15:30,396 --> 00:15:34,933
crucial ingredients for
the next wave of stars.

278
00:15:35,001 --> 00:15:38,136
It's such a beautiful story,
because suddenly the whole

279
00:15:38,171 --> 00:15:40,338
process of star
formation changed,

280
00:15:40,340 --> 00:15:44,642
and it literally became easier
to make a star.

281
00:15:44,711 --> 00:15:49,814
ROWE: Heavy elements suck heat
out of the surrounding gas.

282
00:15:49,916 --> 00:15:53,217
Cooler clouds crunch down
must faster.

283
00:15:53,286 --> 00:15:57,121
The smaller, second-generation
stars form rapidly

284
00:15:57,190 --> 00:16:00,191
and in much greater numbers.

285
00:16:00,326 --> 00:16:04,395
Somehow, this mess of stars
transformed into a network

286
00:16:04,464 --> 00:16:07,465
of young galaxies,
but it wasn't easy,

287
00:16:07,467 --> 00:16:10,034
because as these
baby galaxies formed,

288
00:16:10,103 --> 00:16:12,937
a breed of
matter-hungry monsters

289
00:16:13,006 --> 00:16:16,240
appeared in
the young cosmic web.

290
00:16:22,582 --> 00:16:26,684
ROWE: 13.6 billion years ago,
the dark scaffold

291
00:16:26,686 --> 00:16:29,620
that supports all the regular
matter in the universe

292
00:16:29,656 --> 00:16:32,790
emerges, ablaze with stars.

293
00:16:35,395 --> 00:16:38,129
But how did this stellar
array evolve into a structure

294
00:16:38,197 --> 00:16:40,965
littered with
organized galaxies?

295
00:16:41,001 --> 00:16:45,603
It seems they formed under
constant threat of destruction.

296
00:16:49,776 --> 00:16:51,309
October 2020.

297
00:16:51,411 --> 00:16:54,946
Astronomers discover
a monster lurking

298
00:16:55,014 --> 00:16:58,316
among the cosmic web's
earliest structures,

299
00:16:58,385 --> 00:17:02,387
dating to 900 million years
after the Big Bang,

300
00:17:02,389 --> 00:17:05,223
a supermassive black hole.

301
00:17:05,291 --> 00:17:09,293
Six galaxies surround
this cosmic giant,

302
00:17:09,295 --> 00:17:11,963
caught in its grip,
seemingly linked to

303
00:17:12,031 --> 00:17:14,732
the supermassive black hole
by filaments

304
00:17:14,768 --> 00:17:18,603
of the developing cosmic web.

305
00:17:18,671 --> 00:17:22,707
It's like the universe has
given supermassive black holes

306
00:17:22,776 --> 00:17:24,142
an umbilical cord.

307
00:17:24,210 --> 00:17:28,479
It's like an all-you-can-eat
buffet, right there.

308
00:17:28,481 --> 00:17:32,950
ROWE: Supermassive black holes
are hungry beasts.

309
00:17:33,052 --> 00:17:37,388
They feast on any matter
that gets too close to them.

310
00:17:37,490 --> 00:17:40,324
MINGARELLI: Supermassive black
holes are likely some of

311
00:17:40,393 --> 00:17:43,494
the most powerful objects
in the universe.

312
00:17:43,596 --> 00:17:47,498
They can be anywhere between
100,000 to 10 billion

313
00:17:47,600 --> 00:17:49,534
times the mass of the sun.

314
00:17:49,602 --> 00:17:53,037
ROWE: Supermassive black holes
have been a nemesis

315
00:17:53,073 --> 00:17:56,040
for generations of scientists,
not because of

316
00:17:56,109 --> 00:17:59,777
their fearsome nature,
but because nobody knows

317
00:17:59,879 --> 00:18:02,613
how they grew so large,
so early.

318
00:18:02,682 --> 00:18:05,950
SUTTER: I wish I knew where
supermassive black holes

319
00:18:06,019 --> 00:18:08,086
came from -- if I knew,
I would have a Nobel Prize

320
00:18:08,088 --> 00:18:09,587
hanging around my neck,
and I would wear it

321
00:18:09,656 --> 00:18:11,222
every single day.

322
00:18:13,093 --> 00:18:17,395
As someone who deeply
loves supermassive black holes,

323
00:18:17,497 --> 00:18:20,131
whose career is based on
studying supermassive

324
00:18:20,200 --> 00:18:22,967
black holes, it is very
frustrating to not

325
00:18:22,969 --> 00:18:24,702
know where they come from.

326
00:18:24,804 --> 00:18:27,939
ROWE: Regular stellar
black holes are the collapsed

327
00:18:28,040 --> 00:18:30,975
cores of dead stars,
ranging from

328
00:18:30,977 --> 00:18:34,378
three to thousands of
solar masses,

329
00:18:34,380 --> 00:18:39,484
but supermassive black holes,
those are a different beast.

330
00:18:39,552 --> 00:18:42,386
Thirteen billion years ago,
not enough stars

331
00:18:42,489 --> 00:18:45,790
had lived and died to build
something as huge

332
00:18:45,925 --> 00:18:48,192
as a supermassive black hole.

333
00:18:51,297 --> 00:18:54,665
Now, the cosmic web offers
scientists clues

334
00:18:54,667 --> 00:18:56,801
about the black hole conundrum.

335
00:18:56,903 --> 00:19:01,038
We now know supermassive
black holes grow

336
00:19:01,107 --> 00:19:04,475
among the lattice of
the young cosmic web,

337
00:19:04,477 --> 00:19:08,613
gorging on the hydrogen gas that
travels along the filaments.

338
00:19:10,116 --> 00:19:12,216
At the same time,
when the cosmic web

339
00:19:12,285 --> 00:19:15,786
is lighting up,
supermassive black holes

340
00:19:15,889 --> 00:19:20,124
appear to be stealing star fuel
from the young universe.

341
00:19:20,193 --> 00:19:23,961
You might think that would
kill a growing galaxy,

342
00:19:24,030 --> 00:19:28,799
and yet most mature galaxies
have a supermassive black hole.

343
00:19:28,901 --> 00:19:32,003
They really dominate
the physics of what happens

344
00:19:32,005 --> 00:19:34,639
in the centers of galaxies,
and even how galaxies

345
00:19:34,707 --> 00:19:36,507
can evolve.

346
00:19:36,609 --> 00:19:39,610
ROWE: We think these galactic
monsters have been around

347
00:19:39,679 --> 00:19:42,813
from the start --
How then did the web's

348
00:19:42,916 --> 00:19:47,685
young galaxies develop around
supermassive black holes?

349
00:19:47,687 --> 00:19:51,989
The Milky Way's supermassive
black hole is called

350
00:19:51,991 --> 00:19:54,225
Sagittarius A-Star.

351
00:19:54,294 --> 00:19:58,062
It's around 27 million miles
wide and weighs in

352
00:19:58,130 --> 00:20:01,199
at just over 4 million
solar masses.

353
00:20:03,570 --> 00:20:07,171
MINGARELLI: The environment
around Sagittarius A-Star

354
00:20:07,173 --> 00:20:09,807
is very dynamic --
It can actually be

355
00:20:09,909 --> 00:20:13,344
a really hellish place --
There's this accretion disk

356
00:20:13,412 --> 00:20:15,179
that's full of plasma,
it's heated to

357
00:20:15,181 --> 00:20:18,482
thousands of degrees,
so you wouldn't necessarily

358
00:20:18,551 --> 00:20:21,352
think that that's a great
place for star formation

359
00:20:21,420 --> 00:20:23,254
to happen.

360
00:20:23,322 --> 00:20:26,057
ROWE: But that's exactly
where astronomers

361
00:20:26,059 --> 00:20:28,526
decided to look.

362
00:20:28,561 --> 00:20:31,662
Using the Atacama Large
Millimeter Array,

363
00:20:31,664 --> 00:20:34,699
or ALMA for short,
scientists scan

364
00:20:34,767 --> 00:20:39,470
the heart of the Milky Way
for dense cores of gas and dust,

365
00:20:39,472 --> 00:20:41,939
stellar embryos.

366
00:20:42,041 --> 00:20:46,444
They found more than 800 within
just a thousand lightyears

367
00:20:46,512 --> 00:20:48,145
of Sagittarius A-Star,

368
00:20:48,181 --> 00:20:52,783
including more than 40 embryos
with energetic jets

369
00:20:52,785 --> 00:20:55,953
blasting from their cores,
the telltale sign

370
00:20:56,022 --> 00:20:58,055
of the birth of stars.

371
00:21:02,028 --> 00:21:03,527
MINGARELLI: It's really
surprising to find

372
00:21:03,629 --> 00:21:05,730
those stars there --
It's like hearing

373
00:21:05,798 --> 00:21:08,399
babies' cries from a wolf's den.

374
00:21:10,803 --> 00:21:12,937
PLAIT: It's not the place
you would expect this to happen,

375
00:21:13,006 --> 00:21:15,573
but in fact, stars are
forming there.

376
00:21:15,575 --> 00:21:17,875
Now, it's not as efficient
as it is out here

377
00:21:17,877 --> 00:21:20,978
in the suburbs where things are
quieter, but it works.

378
00:21:20,980 --> 00:21:25,383
ROWE: Baby stars igniting
and thriving around

379
00:21:25,385 --> 00:21:28,486
a supermassive black hole,
the kind of

380
00:21:28,488 --> 00:21:31,322
hostile environment we know
existed in the young

381
00:21:31,424 --> 00:21:35,426
cosmic web --
Star birth is a key part

382
00:21:35,494 --> 00:21:38,462
of kickstarting young galaxies.

383
00:21:38,464 --> 00:21:41,399
This evidence suggests
that star formation

384
00:21:41,467 --> 00:21:44,368
is more resilient
than researchers thought,

385
00:21:44,370 --> 00:21:48,306
and they've developed a theory
to explain it.

386
00:21:48,374 --> 00:21:51,676
Gas and dust race around
the black hole

387
00:21:51,678 --> 00:21:54,345
in the accretion disk --
Heated to incredible

388
00:21:54,380 --> 00:21:57,448
temperatures, plumes of gas
break off

389
00:21:57,516 --> 00:21:59,317
and blast into space.

390
00:21:59,418 --> 00:22:01,686
The gas rapidly cools,
collapses,

391
00:22:01,754 --> 00:22:06,290
and forms baby stars --
These accretion disks

392
00:22:06,392 --> 00:22:09,694
are the most chaotic of
stellar nurseries.

393
00:22:09,762 --> 00:22:12,963
You see this mechanism that
you think is violently

394
00:22:13,032 --> 00:22:15,266
inhibiting star formation,
and at the same time,

395
00:22:15,268 --> 00:22:17,501
it's triggering the birth
of new stars.

396
00:22:17,603 --> 00:22:22,740
ROWE: Matter clumps at
the cosmic web's intersections,

397
00:22:22,808 --> 00:22:26,043
feeding the supermassive
black holes.

398
00:22:26,145 --> 00:22:29,413
Around them,
stars burst into life,

399
00:22:29,482 --> 00:22:31,716
slowly building galaxies.

400
00:22:31,751 --> 00:22:35,386
This could be how our own
Milky Way formed

401
00:22:35,488 --> 00:22:39,490
among the filaments
of the young cosmic web.

402
00:22:39,592 --> 00:22:44,495
But new research suggests that
growth in these baby galaxies

403
00:22:44,597 --> 00:22:47,998
requires murder and mayhem,
and without them,

404
00:22:48,000 --> 00:22:50,134
we wouldn't exist.

405
00:22:59,045 --> 00:23:01,812
ROWE: The infant universe
is a dramatic place.

406
00:23:01,914 --> 00:23:05,950
Stars ignite, and stars die,

407
00:23:06,051 --> 00:23:10,354
even in the violent surroundings
of supermassive black holes.

408
00:23:10,423 --> 00:23:15,993
Baby galaxies form
with the cosmic web.

409
00:23:15,995 --> 00:23:17,561
But how do they grow?

410
00:23:17,563 --> 00:23:21,399
Scientists believe the critical
factor is galactic turmoil.

411
00:23:24,570 --> 00:23:26,337
The universe does need
to churn things up.

412
00:23:26,405 --> 00:23:28,105
You need to break some eggs
to make an omelet.

413
00:23:28,207 --> 00:23:30,508
You need to introduce some
chaos into your galaxy

414
00:23:30,609 --> 00:23:34,311
to rapidly form stars
or grow black holes.

415
00:23:34,380 --> 00:23:39,517
Smashing things together
is how the universe came to be.

416
00:23:39,585 --> 00:23:44,054
ROWE: The Hubble Space Telescope
discovers many distorted

417
00:23:44,090 --> 00:23:49,360
galaxies -- twisted,
battered, and torn,

418
00:23:49,395 --> 00:23:53,397
victims of violent collisions
on a cosmic scale.

419
00:23:53,399 --> 00:23:58,402
HOPKINS: Galaxies are never
sitting quietly, doing nothing.

420
00:23:58,504 --> 00:24:01,806
They're always undergoing
change -- they're constantly

421
00:24:01,874 --> 00:24:04,475
encountering and slamming
into and colliding with

422
00:24:04,477 --> 00:24:06,377
and mixing with other galaxies.

423
00:24:06,379 --> 00:24:09,380
MINGARELLI:
You can see images in Hubble

424
00:24:09,382 --> 00:24:11,982
of total car wrecks,
of galaxies that are

425
00:24:11,984 --> 00:24:13,717
trying to merge with each other.

426
00:24:16,489 --> 00:24:19,457
ROWE: We know that galaxies
collide now,

427
00:24:19,459 --> 00:24:21,992
but what about
in the early universe,

428
00:24:21,994 --> 00:24:25,062
when the cosmic web was
beginning to take shape?

429
00:24:25,130 --> 00:24:30,334
Astronomers study a strange
galaxy named Himiko,

430
00:24:30,336 --> 00:24:33,704
born just 800 million years
after the Big Bang.

431
00:24:35,775 --> 00:24:40,277
Three bright light sources
suggest intense star formation.

432
00:24:40,279 --> 00:24:43,747
Detailed analysis reveals
not one galaxy,

433
00:24:43,749 --> 00:24:47,885
but three baby galaxies,
not yet fully formed.

434
00:24:50,356 --> 00:24:55,459
Scientists call these youthful
star systems protogalaxies.

435
00:24:55,461 --> 00:24:59,563
The trio that make up
Himiko are in mid-collision.

436
00:24:59,565 --> 00:25:04,702
Computer simulations of
the early universe suggest

437
00:25:04,803 --> 00:25:10,140
protogalaxies smashed together
with frightening regularity.

438
00:25:10,176 --> 00:25:13,043
These violent shake-ups
trigger star birth.

439
00:25:13,112 --> 00:25:16,981
Protogalaxies are rich in gas,

440
00:25:16,983 --> 00:25:19,316
and when they collide and merge,
those gas clouds

441
00:25:19,385 --> 00:25:21,619
collide and collapse
and form stars,

442
00:25:21,654 --> 00:25:24,989
sometimes, at prodigious rates,
and after a billion years

443
00:25:24,991 --> 00:25:27,157
or so, all of that structure
forms, and you get

444
00:25:27,226 --> 00:25:29,193
a formal galaxy.

445
00:25:30,696 --> 00:25:32,263
ROWE:
Picture the early universe,

446
00:25:32,265 --> 00:25:35,132
500 million years after
the Big Bang.

447
00:25:35,234 --> 00:25:38,102
It's smaller and more compact
than today.

448
00:25:38,203 --> 00:25:40,604
Cosmic collisions are common.

449
00:25:42,141 --> 00:25:44,441
PLAIT: Imagine taking a bunch
of cars and just letting them

450
00:25:44,477 --> 00:25:46,076
drive around in Nevada where

451
00:25:46,078 --> 00:25:47,611
there's nothing but space,
right?

452
00:25:47,680 --> 00:25:49,513
You're not gonna get
too many collisions.

453
00:25:49,549 --> 00:25:52,116
Now squeeze them into
a tiny little city block

454
00:25:52,251 --> 00:25:54,818
some place, and you're just
gonna have accidents everywhere.

455
00:25:54,921 --> 00:25:56,720
Well, it's the same thing
with the universe.

456
00:25:56,756 --> 00:25:58,989
When the universe was younger,
it was smaller,

457
00:25:58,991 --> 00:26:01,125
and these protogalaxies
were everywhere.

458
00:26:01,160 --> 00:26:02,426
It was crowded.

459
00:26:02,428 --> 00:26:05,529
You were bound to get collisions
between them back then.

460
00:26:05,565 --> 00:26:09,099
ROWE: More and more baby
galaxies form at the growing

461
00:26:09,101 --> 00:26:12,303
web's gas-rich intersections.

462
00:26:12,371 --> 00:26:14,872
A collision between small
protogalaxies

463
00:26:14,874 --> 00:26:18,776
might trigger modest amounts
of star formation

464
00:26:18,778 --> 00:26:23,347
when regions of dense matter
come together.

465
00:26:23,415 --> 00:26:25,749
But a merger involving

466
00:26:25,751 --> 00:26:29,019
protogalaxies with rich
reserves of gas

467
00:26:29,088 --> 00:26:31,322
can rev up the rate of
stellar ignition,

468
00:26:31,390 --> 00:26:35,459
supercharging a growing galaxy.

469
00:26:35,461 --> 00:26:38,562
Gas-rich mergers can
generate starburst galaxies,

470
00:26:38,564 --> 00:26:41,932
where we see incredibly vigorous
events of star formation.

471
00:26:42,001 --> 00:26:46,403
ROWE: Astronomers think
one such smash-up,

472
00:26:46,405 --> 00:26:49,607
around 10 billion years ago,
kickstarted the growth

473
00:26:49,708 --> 00:26:51,275
of the Milky Way.

474
00:26:51,277 --> 00:26:55,079
A group of stars called
the Gaia Enceladus Cluster

475
00:26:55,081 --> 00:26:57,348
in the outer reaches of
the galaxy

476
00:26:57,416 --> 00:27:01,151
behaves strangely compared
to other stars around it.

477
00:27:01,220 --> 00:27:04,755
SUTTER: The stars
in the Gaia Enceladus Cluster,

478
00:27:04,757 --> 00:27:07,391
they're different,
they move differently,

479
00:27:07,493 --> 00:27:09,259
they act different,
they're like -- they're like

480
00:27:09,261 --> 00:27:12,429
kids from the next town over
showing up at your school.

481
00:27:12,498 --> 00:27:15,132
You just know
that they don't belong.

482
00:27:15,200 --> 00:27:18,702
The Milky Way had already
largely formed,

483
00:27:18,804 --> 00:27:22,606
and then this massive cluster
comes screaming in.

484
00:27:22,708 --> 00:27:24,875
It was a violent event

485
00:27:24,877 --> 00:27:28,712
that eventually ended up
absorbing the stars

486
00:27:28,814 --> 00:27:31,048
from this cluster
into the body of

487
00:27:31,116 --> 00:27:33,050
the Milky Way itself.

488
00:27:33,118 --> 00:27:37,388
Galaxies are built from
these kinds of collisions.

489
00:27:37,489 --> 00:27:41,592
ROWE: Less than a billion years
after the Big Bang,

490
00:27:41,661 --> 00:27:45,496
the dark scaffold of the cosmic
web begins to glow.

491
00:27:45,564 --> 00:27:49,800
Matter channeled down the web's
tendrils creates

492
00:27:49,935 --> 00:27:53,537
dense clumps of gas --
Even in the turbulent

493
00:27:53,605 --> 00:27:56,740
neighborhoods of supermassive
black holes,

494
00:27:56,809 --> 00:27:59,677
stars burst into life.

495
00:27:59,679 --> 00:28:03,547
Baby galaxies collide,
and the young universe

496
00:28:03,615 --> 00:28:05,582
sparkles with light.

497
00:28:05,584 --> 00:28:10,087
But an important
question remains.

498
00:28:10,089 --> 00:28:12,589
In the mayhem of
the early universe,

499
00:28:12,692 --> 00:28:15,592
how did galaxies
like our Milky Way

500
00:28:15,694 --> 00:28:17,728
survive and thrive?

501
00:28:20,366 --> 00:28:23,100
MINGARELLI: Galaxy evolution
is very dynamic.

502
00:28:23,102 --> 00:28:26,470
Our understanding of galaxy
evolution is very dynamic,

503
00:28:26,472 --> 00:28:29,573
and there's so much that
we still don't know.

504
00:28:29,575 --> 00:28:31,408
There's a lot of different
competing theories

505
00:28:31,477 --> 00:28:34,678
right now as to how galaxies
grew into the galaxies

506
00:28:34,780 --> 00:28:36,080
that we see today.

507
00:28:38,184 --> 00:28:39,783
It's a huge open question,
and it's something that's

508
00:28:39,885 --> 00:28:41,952
a big deal in science right now.

509
00:28:41,987 --> 00:28:45,789
ROWE: New research suggests
that life and death

510
00:28:45,891 --> 00:28:48,826
in the cradle of the universe
lay within

511
00:28:48,928 --> 00:28:50,961
the cosmic web.

512
00:28:58,804 --> 00:29:01,105
ROWE: 13.6 billion years ago,

513
00:29:01,173 --> 00:29:04,007
a protogalaxy,
the infant Milky Way,

514
00:29:04,009 --> 00:29:09,213
forms in the tendrils of
the young cosmic web.

515
00:29:09,314 --> 00:29:11,181
Today, it bears the scars

516
00:29:11,183 --> 00:29:12,883
of many collisions.

517
00:29:12,885 --> 00:29:15,486
Each one could have
torn it apart.

518
00:29:15,488 --> 00:29:19,590
So what controls if a young
galaxy lives or dies?

519
00:29:21,260 --> 00:29:23,193
May 2020.

520
00:29:23,195 --> 00:29:26,964
Scientists image a graceful
galaxy that existed

521
00:29:27,032 --> 00:29:30,400
just 1.4 billion years
after the Big Bang.

522
00:29:30,502 --> 00:29:35,038
Analysis of its light shows this

523
00:29:35,074 --> 00:29:39,176
is a starburst galaxy,
pumping out newborn stars.

524
00:29:39,178 --> 00:29:42,880
Galaxies like our Milky Way
are old and rather stately,

525
00:29:42,882 --> 00:29:45,883
and they don't form stars
very rapidly --

526
00:29:45,885 --> 00:29:49,286
About the equivalent of the mass
of the sun every year.

527
00:29:49,288 --> 00:29:51,488
Well, starburst galaxies --
Yeah, they form them

528
00:29:51,623 --> 00:29:55,659
a lot more quickly -- hundreds
of solar masses per year.

529
00:29:55,661 --> 00:29:59,396
But BRI 1335-0417,

530
00:29:59,398 --> 00:30:03,400
4,650 times the mass of
the sun every year.

531
00:30:03,502 --> 00:30:06,003
It is blasting out stars.

532
00:30:08,274 --> 00:30:10,607
ROWE: Some young galaxies
in the early universe

533
00:30:10,709 --> 00:30:14,378
appear to be supercharged
with star fuel.

534
00:30:14,380 --> 00:30:17,514
How can they grow at such
an incredible pace?

535
00:30:20,553 --> 00:30:23,887
Scientists think the answer
lies in the mysterious substance

536
00:30:23,889 --> 00:30:27,591
that's controlled the flow
of gas since the beginning --

537
00:30:27,593 --> 00:30:30,427
The dark structure
whose tendrils stitch

538
00:30:30,496 --> 00:30:33,096
the universe together,

539
00:30:33,199 --> 00:30:38,202
but exploring this cosmic
network is no easy task.

540
00:30:38,303 --> 00:30:40,204
When it comes to dark matter,

541
00:30:40,206 --> 00:30:42,406
we're flying blind.

542
00:30:46,579 --> 00:30:48,111
May 2021.

543
00:30:48,213 --> 00:30:51,148
An international team of
researchers investigates

544
00:30:51,216 --> 00:30:54,885
dark matter in the local
universe by observing

545
00:30:54,887 --> 00:30:58,355
its effect on the path of light.

546
00:30:58,357 --> 00:31:00,958
Gravity affects light.

547
00:31:01,026 --> 00:31:05,062
A massive object causes light
to curve

548
00:31:05,130 --> 00:31:08,532
through space, even if
that object is invisible,

549
00:31:08,600 --> 00:31:09,933
like dark matter.

550
00:31:11,604 --> 00:31:13,737
We can't see the dark matter
directly, but we can see

551
00:31:13,805 --> 00:31:16,306
what it's doing to the light --
It's stretching it,

552
00:31:16,375 --> 00:31:18,542
it's bending it,
it's creating arcs in ways

553
00:31:18,610 --> 00:31:22,112
that would never happen unless
the dark matter were there.

554
00:31:22,214 --> 00:31:24,948
ROWE: Using an AI program,

555
00:31:25,050 --> 00:31:28,819
the team analyzes 100 million
visible galaxies,

556
00:31:28,921 --> 00:31:32,189
looking for
warped galactic light.

557
00:31:32,191 --> 00:31:34,725
Because the model is
artificially intelligent,

558
00:31:34,793 --> 00:31:38,729
it gets better and better
at finding dark matter.

559
00:31:41,667 --> 00:31:45,002
What's very clever
about this kind of algorithm

560
00:31:45,004 --> 00:31:47,471
is that it's learning
as it goes.

561
00:31:47,473 --> 00:31:49,940
It uses the information
that it has

562
00:31:50,008 --> 00:31:53,944
to predict the existence
of new structures.

563
00:31:54,012 --> 00:31:56,780
ROWE: As the model teaches
itself to see

564
00:31:56,882 --> 00:31:58,949
the dark matter behind
the stars,

565
00:31:59,017 --> 00:32:02,386
it maps out new,
dark structures,

566
00:32:02,388 --> 00:32:06,256
never-before-seen highways
between galaxies.

567
00:32:06,292 --> 00:32:08,392
There's a lot more filaments,
there's a lot more

568
00:32:08,394 --> 00:32:11,828
intricacies, there's a lot
more cosmic web there

569
00:32:11,931 --> 00:32:13,697
than what meets the eye.

570
00:32:13,766 --> 00:32:17,000
It's like if you look how

571
00:32:17,002 --> 00:32:21,004
Manhattan is connected
to the land around it,

572
00:32:21,006 --> 00:32:23,373
you can see all the bridges,
but now we're also seeing

573
00:32:23,375 --> 00:32:25,108
the underwater tunnels.

574
00:32:25,243 --> 00:32:29,046
ROWE: The new layout
of dark matter reveals

575
00:32:29,114 --> 00:32:32,716
the local universe is a bird's
nest of hidden channels,

576
00:32:32,784 --> 00:32:35,218
feeding galaxies with gas.

577
00:32:38,023 --> 00:32:40,290
Galactic structures seem
to thrive

578
00:32:40,292 --> 00:32:44,328
at the cosmic web's most
densely-knotted intersections.

579
00:32:46,465 --> 00:32:48,799
Because multiple filaments
are intersected

580
00:32:48,867 --> 00:32:51,301
in those locations,
and that is a location

581
00:32:51,403 --> 00:32:54,871
of very enhanced gravity
relative to other locations,

582
00:32:54,873 --> 00:32:57,207
the material will be drawn in,

583
00:32:57,209 --> 00:33:00,944
so these galaxy clusters are
likely feeding off

584
00:33:01,013 --> 00:33:02,379
the cosmic web.

585
00:33:02,381 --> 00:33:07,284
ROWE: This connectivity could be
the key to the rapidly-forming

586
00:33:07,286 --> 00:33:13,223
galaxies in the early universe,
but there's a catch.

587
00:33:13,291 --> 00:33:15,726
Sitting right at the densest
regions of

588
00:33:15,794 --> 00:33:18,895
the cosmic web can be really
good for galaxy growth.

589
00:33:18,897 --> 00:33:21,198
You have all of this gas
being funneled in

590
00:33:21,200 --> 00:33:24,401
for a new star formation,
but being that plugged in

591
00:33:24,503 --> 00:33:26,770
to the network isn't
all good news.

592
00:33:26,772 --> 00:33:30,107
ROWE: There is evidence that,
though the cosmic web

593
00:33:30,208 --> 00:33:34,511
gives life, it can also
take life away.

594
00:33:34,613 --> 00:33:37,514
Scientists studying some of
the universe's most heavily

595
00:33:37,583 --> 00:33:40,484
connected galaxies
found something unexpected --

596
00:33:40,552 --> 00:33:43,820
Plummeting rates of star birth.

597
00:33:43,922 --> 00:33:46,723
In some ways, it's a little bit
counter-intuitive, right?

598
00:33:46,792 --> 00:33:49,993
If these nodes are meeting
grounds for all of

599
00:33:49,995 --> 00:33:54,297
this gas, right, why aren't
you forming more stars there?

600
00:33:56,168 --> 00:33:58,502
ROWE: One explanation?
In the all-you-can-eat buffet

601
00:33:58,570 --> 00:34:01,972
of the cosmic web's
matter-rich junctions,

602
00:34:01,974 --> 00:34:04,541
a young galaxy might
over-indulge.

603
00:34:04,609 --> 00:34:10,347
As the cosmic web funnels
more matter towards a junction

604
00:34:10,415 --> 00:34:13,583
and its growing galaxies,
the gas influx doesn't

605
00:34:13,652 --> 00:34:17,754
just boost star formation,
it fattens up

606
00:34:17,756 --> 00:34:21,958
the supermassive black hole
at the galaxy's core.

607
00:34:22,027 --> 00:34:24,761
For a young galaxy,
that's dangerous,

608
00:34:24,763 --> 00:34:28,331
because when this monster
over-eats, it produces

609
00:34:28,433 --> 00:34:31,802
high-energy jets and belches out

610
00:34:31,904 --> 00:34:33,437
super hot wind.

611
00:34:33,505 --> 00:34:37,774
These black holes radiate
tremendous amounts of energy

612
00:34:37,909 --> 00:34:40,310
when they grow,
and that radiation can

613
00:34:40,412 --> 00:34:42,946
slam into the material
around them in the galaxy

614
00:34:42,981 --> 00:34:45,315
and blow it all out of
the galaxy, launch it away

615
00:34:45,384 --> 00:34:48,151
or heat it up to
super high temperatures.

616
00:34:48,187 --> 00:34:51,822
Star formation requires stuff,
so if you blow that stuff

617
00:34:51,924 --> 00:34:54,024
away, how are you gonna
form a star?

618
00:34:57,262 --> 00:34:59,229
And what's left behind
would be what we call

619
00:34:59,264 --> 00:35:03,700
a quenched galaxy that basically
can't form any new stars.

620
00:35:03,802 --> 00:35:06,670
ROWE: The researchers found
that although connectivity

621
00:35:06,672 --> 00:35:10,107
within the cosmic web can boost
galactic growth,

622
00:35:10,208 --> 00:35:13,009
it was the super connected
galaxies that died

623
00:35:13,011 --> 00:35:18,348
the quickest, choked and stunted
like over-watered plants.

624
00:35:18,416 --> 00:35:22,953
Perhaps our Milky Way got lucky.

625
00:35:23,021 --> 00:35:26,356
You could say that
the Milky Way Galaxy is sort of

626
00:35:26,358 --> 00:35:29,192
in this Goldilocks zone
of galaxy formation.

627
00:35:29,194 --> 00:35:32,229
It's been receiving enough
gas over time that it's

628
00:35:32,297 --> 00:35:34,297
been able to keep up with
its star formation

629
00:35:34,366 --> 00:35:38,001
but not so much gas that
its central black hole

630
00:35:38,003 --> 00:35:41,271
has been fed enough that
it would clear the galaxy

631
00:35:41,273 --> 00:35:42,973
out of gas.

632
00:35:42,975 --> 00:35:47,110
ROWE: The cosmic web determined
if galaxies lived or died.

633
00:35:47,179 --> 00:35:51,681
Its construction project
brought order to chaos.

634
00:35:51,750 --> 00:35:57,087
The cosmic web is
the architect, the engineer,

635
00:35:57,089 --> 00:36:00,223
the builder, the construction
worker, even the interior

636
00:36:00,292 --> 00:36:02,325
designer of the cosmos.

637
00:36:04,663 --> 00:36:07,130
ROWE: But now,
work has shut down.

638
00:36:07,199 --> 00:36:10,467
An invisible force threatens
to tear apart the very

639
00:36:10,469 --> 00:36:14,371
fabric of the cosmic web --
What does this mean

640
00:36:14,373 --> 00:36:16,873
for galaxies and for us?

641
00:36:27,085 --> 00:36:30,654
ROWE: The cosmic web brought
order to the early universe.

642
00:36:30,656 --> 00:36:34,257
The gravitational attraction
of its dark scaffolding

643
00:36:34,259 --> 00:36:37,827
helped build galaxies
and fueled their development.

644
00:36:37,963 --> 00:36:43,033
But growth tops out at
the level of galaxy clusters.

645
00:36:43,101 --> 00:36:45,902
Nothing bigger will ever form.

646
00:36:45,904 --> 00:36:49,873
Something has stopped
the formation of structure

647
00:36:49,875 --> 00:36:51,441
in our universe.

648
00:36:51,509 --> 00:36:54,611
ROWE: To understand
what's going on,

649
00:36:54,680 --> 00:36:56,613
we need to return to
the Big Bang

650
00:36:56,682 --> 00:36:58,949
and the formation of
the cosmic web.

651
00:37:03,088 --> 00:37:08,391
13.8 billion years ago,
the universe sparks into life.

652
00:37:08,493 --> 00:37:12,495
A tiny ball of pure energy
cools and expands.

653
00:37:15,100 --> 00:37:18,034
The energy transforms into
regular matter

654
00:37:18,136 --> 00:37:22,472
and dark matter,
but another force appears

655
00:37:22,474 --> 00:37:26,209
at the same time -- dark energy.

656
00:37:29,414 --> 00:37:31,681
Dark energy,
as far as we understand it,

657
00:37:31,683 --> 00:37:34,951
which is not much,
has always been here.

658
00:37:35,053 --> 00:37:37,354
It's always been a part of
the universe,

659
00:37:37,422 --> 00:37:40,423
but it's been silent,
in the background.

660
00:37:40,492 --> 00:37:44,194
Dark energy is everywhere --
It's over here,

661
00:37:44,296 --> 00:37:46,796
it's over there,
it's between you and me.

662
00:37:46,898 --> 00:37:48,598
It's absolutely everywhere.

663
00:37:48,700 --> 00:37:52,202
One theory is that dark energy
never formed,

664
00:37:52,304 --> 00:37:54,537
that it's just a constant
in the laws of physics

665
00:37:54,573 --> 00:37:56,740
that has always been there
and always will be.

666
00:37:56,808 --> 00:38:01,244
ROWE: Some physicists believe
that dark energy

667
00:38:01,246 --> 00:38:05,248
is simply the force
of emptiness.

668
00:38:05,317 --> 00:38:09,319
TEGMARK: People used to take for
granted that space was empty,

669
00:38:09,388 --> 00:38:13,290
a vacuum, but the discovery
of dark energy

670
00:38:13,292 --> 00:38:15,525
has made some people wonder
if space is actually

671
00:38:15,593 --> 00:38:19,529
more of a substance,
and, um, that space also

672
00:38:19,597 --> 00:38:21,298
might have pressure that
causes things

673
00:38:21,399 --> 00:38:25,368
to push apart, so, you know,
whatever space is,

674
00:38:25,370 --> 00:38:28,204
it might be more interesting
than we thought.

675
00:38:28,306 --> 00:38:31,975
ROWE: Dark matter
dominates the young universe,

676
00:38:31,977 --> 00:38:36,780
but as the dark scaffold
of the cosmic web grows,

677
00:38:36,782 --> 00:38:39,215
it sows the seeds of
self-destruction.

678
00:38:40,652 --> 00:38:43,820
As the network of matter
takes shape,

679
00:38:43,955 --> 00:38:47,557
pockets of emptiness form
between the filaments --

680
00:38:47,559 --> 00:38:49,292
Cosmic voids.

681
00:38:51,797 --> 00:38:56,666
In these expanding hollow
spaces, dark energy grows.

682
00:38:56,668 --> 00:38:59,836
The weirdest thing about
dark energy is that

683
00:38:59,971 --> 00:39:03,807
it has constant density --
Constant density means

684
00:39:03,875 --> 00:39:08,545
the more volume you have,
the more dark energy you have,

685
00:39:08,613 --> 00:39:11,114
so the larger the voids get,

686
00:39:11,183 --> 00:39:14,384
the more dark energy
they contain.

687
00:39:14,386 --> 00:39:18,154
ROWE: Dark energy pushes
against the cosmic web,

688
00:39:18,223 --> 00:39:20,557
opening up huge chasms in

689
00:39:20,559 --> 00:39:22,559
the architecture
of the universe.

690
00:39:22,561 --> 00:39:25,762
Five billion years ago,
dark matter's strength of

691
00:39:25,764 --> 00:39:29,733
attraction is finally
overwhelmed.

692
00:39:29,801 --> 00:39:32,102
Like bridge cables
in a hurricane,

693
00:39:32,104 --> 00:39:35,505
the cosmic web's filaments
stretch and snap,

694
00:39:35,607 --> 00:39:40,310
and the universe's substructure
fails.

695
00:39:40,412 --> 00:39:45,148
Galactic construction freezes
as the universe expands,

696
00:39:45,216 --> 00:39:48,518
but darker times are ahead
for the cosmic web.

697
00:39:50,088 --> 00:39:53,056
As time goes on,
not only is it expanding,

698
00:39:53,091 --> 00:39:56,059
but this expansion gets faster
and faster and faster.

699
00:39:58,663 --> 00:40:01,030
ROWE: As the dark energy
in the voids increases,

700
00:40:01,133 --> 00:40:03,233
the entire structure of
the cosmic web

701
00:40:03,301 --> 00:40:06,236
begins to break up.

702
00:40:07,906 --> 00:40:11,107
The effects of dark energy
will get stronger

703
00:40:11,109 --> 00:40:13,610
and stronger with time,
until the very fabric

704
00:40:13,678 --> 00:40:15,678
of space time gets torn apart.

705
00:40:15,680 --> 00:40:20,483
This isn't a superhero movie --
The bad guy wins.

706
00:40:20,585 --> 00:40:24,954
The future of the cosmic web
is looking bleak.

707
00:40:24,990 --> 00:40:26,990
Ultimately, it's gonna be

708
00:40:26,992 --> 00:40:29,125
a cold, lonely universe.

709
00:40:29,194 --> 00:40:32,962
ROWE: Our closest galaxies
will accelerate away,

710
00:40:32,998 --> 00:40:36,566
until they're just tiny
pinpricks of light.

711
00:40:36,568 --> 00:40:40,103
Then the universe
will go dark again.

712
00:40:40,205 --> 00:40:42,939
Everything will fade out.

713
00:40:43,008 --> 00:40:45,408
So the universe started
with a bang,

714
00:40:45,477 --> 00:40:48,111
but it will die with a whisper.

715
00:40:48,213 --> 00:40:52,148
ROWE: The cosmic web
transformed the universe

716
00:40:52,217 --> 00:40:56,152
from a hot mess
to a sparkling structure.

717
00:40:56,221 --> 00:41:00,156
It gave birth to billions
of galaxies and us.

718
00:41:00,225 --> 00:41:02,659
Without it, space would be

719
00:41:02,661 --> 00:41:05,128
a much less interesting place.

720
00:41:05,163 --> 00:41:08,264
This giant structure, the
largest thing that we know of

721
00:41:08,266 --> 00:41:12,035
in the universe, is responsible
for nourishing the galaxies,

722
00:41:12,103 --> 00:41:14,671
creating the stars,
making the conditions right

723
00:41:14,673 --> 00:41:18,708
to form life -- we would not
be here, talking right now,

724
00:41:18,776 --> 00:41:20,710
if it were not for
this cosmic web.

725
00:41:20,778 --> 00:41:24,247
SUTTER: Understanding
the cosmic web

726
00:41:24,315 --> 00:41:28,251
is understanding dark matter,
is understanding dark energy,

727
00:41:28,319 --> 00:41:32,889
is understanding our past,
is understanding our future.

728
00:41:32,891 --> 00:41:35,892
Really, everything that we know
about how the universe works

729
00:41:35,894 --> 00:41:39,028
is directly tied
to the cosmic web.

730
00:41:39,064 --> 00:41:42,365
It's amazing to think that
the overall structure of

731
00:41:42,367 --> 00:41:46,769
the universe that we witness
today began in the earliest

732
00:41:46,771 --> 00:41:50,039
times of the universe
and has yielded

733
00:41:50,108 --> 00:41:52,742
beings like ourselves
who can now

734
00:41:52,810 --> 00:41:55,812
discover it and ponder
about its existence.

735
00:41:55,947 --> 00:41:57,347
That's pretty dope.